NATIONAL INSTITUTE OF STANDARDS &

TECHNOLOGY

Research Information Center

Gaithersburg, MD 20890

National

Measurement

Laboratory

Center for

Materials

Science

Annual

Report

1982

NAS-NRC

Evaluation

Panel

November 18-19, 1982

U.S. Department of

Commerce

National Bureau of

Standards

NBSIR 82-2609

National

Measurement

Laboratory

Center for

Materials

Science

NATIONAL BUREAU OF STANDARDS '

Annual

Report

1982

NASNRC

Evaluation

Panel

November 18-19, 1982

John D. Hoffman, Director

National Measurement Laboratory

Robert Mehrabian, Director

Center for Materials Science

NBSIR 82-2609

ABSTRACT

The Center for Materials Science is part of the National Measurement

Laboratory, one of the three major units of the National Bureau of

Standards. Research programs in the Center's five technical divisions

cover the major classes of materials (metals, polymers, ceramics, glass

and composites) and address basic needs for materials measurements,

standards, and data. The Center provides generic technical support for

optimum efficiency in processing, fabrication, and utilization of

materials. Program output is disseminated to a wide range of industrial

users and university researchers by means of workshops, industrial guest

worker interactions, formal and informal laboratory and planning visits,

Center staff standards committee activities, technical publications, and

seminar programs. Two key outputs are standard reference materials for

measurement calibration and evaluated standard reference data. The

Center undertakes materials research in NBS mission areas to support

measurements and standards needs of other Federal agencies. This volume

summarizes the technical activities and accomplishments of the Center

for Materials Science for FY82.

TABLE OF CONTENTS

*

Page

INTRODUCTION 1

CENTER FOR MATERIALS SCIENCE

J. B. Wachtman, Jr. , Director to 8/22/82

R. Mehrabian, Director from 8/22/82 560- 3

Microstructure of Materials 560- 4

Other Center Activities 560- 7

MATERIALS CHEMISTRY DIVISION

T. D. Coyle, Chief 561- 3

Corrosion and Protection of Metals 561- 11

Materials Biotransformations and Chemical Durability in

Service Environments 561- 29

High Temperature Materials Chemistry for Processing

and Durability 561- 49

Properties, Structure, and Standards for Glass and

Optical Materials 561- 73

Ceramic Processing and Durability Science 561- 93

Other Division Activities 561-137

FRACTURE AND DEFORMATION DIVISION

R. P. Reed, Chief 562- 3

Fracture Mechanisms and Analyses 562- 9

Durability of Ceramics and Composites 562- 29

Elastic-Plastic Fracture Mechanics 562- 45

Other Division Activities 562- 53

POLYMER SCIENCE AND STANDARDS DIVISION

R. K. Eby , Chief 563- 3

Polymer Standards for Process Control and Equity .... 563- 13

Tests, Standards, and Characterization for Manufacturing

and Durability of Dental and Medical Materials. . . 563- 27

Mechanical Durability of Polymers 563- 43

Processing and Reliability of Polymer Composites .... 563- 69

Additive Migration and Chemical Durability of Polymers . 563- 79

Microstructure and Performance of Dielectric Plastics. . 563- 95

Other Division Activities 563-107

METALLURGY DIVISION

R. Mehrabian, Acting Chief 564- 3

Structure Characterization . 564- 11

Synchrotron Radiation Research for Materials Science . . 564- 11

Metallurgical Processing 564- 61

Mechanical Properties and Wear 564- 75

Chemical Metallurgy 564- 91

Other Division Activities 564-101

REACTOR RADIATION DIVISION

R. S. Carter, Chief 566- 3

Reactor Operations and Services 566- 9

Advanced Neutron Methods 566- 19

Other Division Activities 566- 23

APPENDIX A1

v
1
INTRODUCTION

The Center for Materials Science (CMS) is located within the National

Measurement Laboratory (NML), one of the three principal laboratories

comprising NBS. The organization structure of the CMS, NML, and NBS,

is given in the Appendix. The Center for Materials Science, one of

the largest Centers at NBS, has approximately 310 staff members (and

approximately 120 guest workers and research associates); ^ 83 percent

of the staff are professionals; of these 55 percent hold Ph.D. degrees.

The operating budget of the Center for FY82 amounted to ^ $23 M.

The Center for Materials Science is responsible for providing data,

measurement methods, standards and reference materials, concepts, and

technical information on the fundamental aspects of processing, structure,

properties and performance of materials to industry, government agencies,

universities, and other scientific organizations. The programs of the

Center support wide generic technologies in materials in order to foster

their safe, efficient, and economical utilization to meet our national

needs within the framework of the materials cycle. The Center also

makes a significant contribution as a national resource of materials

information through its four Data Centers.

The long-term goal of the Center for Materials Science is to support the

private sector and other Government agencies in the most effective

application and utilization of materials —metals, polymers, and inorganic

materials. Center activities in FY82 focused on those aspects of materials

research involving processing science, structure/property science, and

durability science. More specifically the Center:

Develops and maintains scientific competences and experimental

facilities to provide the Nation with a central basis for uniform

physical measurements, measurement methodology, and measurement

services necessary to defining the properties and performance of

materials and to other essential areas in the materials science

di scipl i ne.

Provides technical information in the form of reference data,

materials measurement methods, and standard reference materials.

Information is provided to other agencies of Government, universities, consumers, and to industrial processors, designers, and

materials users to enable them to select cost effective combinations of materials, processes, designs, and service conditions.

Through its measurement research programs, characterizes the

structures of materials, chemical, mechanical, and physical

properties which have wide application throughout the technical

community as a basis for the safe, efficient uses of materials,

the improvement of materials technologies, and the development

and design of innovative materials.

Obtains and disseminates accurate experimental data on the

behavior and properties of materials over time under service

conditions to assure effective utilization of manufactured

materials.

1
T he Center is organized in five Divisions, having responsibilities in

different areas of materials science. The research activities of the

Divisions are structured according to a task system; each task has specific

goals, objectives, and milestones which support the overall goals of the

Center. The following listing tabulates the tasks for each Division.

Detailed descriptions of the FY82 technical activities encompassed by the

various tasks are given in the following sections.

2
560 Task Numbers, Titles, and Leaders

Center Office

12101 Microstructure of Materials

561 Materials Chemistry Division

12113 Corrosion and Protection of Metals

12114 Materials Biotransformations and

Chemical Durability in Service

Envi ronments

12115 High Temperature Materials Chemistry

for Processing and Durability

12154 Properties, Structure, and Standards

for Glass and Optical Materials

12156 Ceramic Processing and Durability

Science

Recycled Oil Program

562 Fracture and Deformation Division

12121 Fracture Mechanisms and Analyses

12122 Durability of Ceramics and Composites

12123 Elastic Plastic Fracture Mechanisms

563 Polymer Science and Standards Divisior

12132 Polymer Standards for Process Control

and Equity

12135 Tests, Standards, and Characterization

for Manufacturing and Durability of

Dental and Medical Materials

12136 Mechanical Durability of Polymers

12137 Processing and Reliability of Polymer

Composites

12138 Additive Migration and Chemical

Durability of Polymers

12139 Dielectric Plastics: Microstructure

and Performance

J. B. Wachtman, Jr.

to 8/22/82

R. Mehrabian fro - 8/22/82

J. Kruger

F. E. Brinckman

J. W. Hastie

W. K. Haller

T. Negas

S. Hsu

E. R. Fuller, Jr.

S. M. Wiederhorn

H. I. McHenry

I. C. Sanchez

J. M. Cassel

B. M. Fanconi

B. M. Fanconi

F. W. Wang

G. T. Davis

564 Metallurgy Divisior

12142 Structure Characterization M. Kuriyama

12143 Metallurgical Processing J. R. Manning

12144 Mechanical Properties and Wear A. W. Ruff

12145 Chemical Metallurgy R. ^emrabian

51105 Synchrotron Radiation Research for

Materials Science

M. Kuriyama

3
566 Reactor Radiation Division

12161

12162

12163

51102

Reactor Operations and Services T. M. Raby

Neutron Scattering Characterization of J. J. Rush

Materials for Advanced Technologies

Neutron Structure Methods and Crystal J. J. Rush

Data Base for Materials Utilization

Advanced Neutron Methods J. M. Rowe

4
1

OFFICE OF THE CENTER FOR MATERIALS SCIENCE

John B. Wachtman, Jr., Director to 8/22/82

Robert Mehrabian, Director from 8/22/82

Darrell H. Reneker, Deputy Director

Suzanne H. Bussard, Secretary

The Center Office is responsible for providing the technical and administrative framework for the planning and operation of the programs carried

out by the five technical Divisions and the Center Office scientists.

The Center provides technical support to the Administration's activities

on national materials policy. A draft chapter on Technical Trends in

Materials use was prepared for the Office of Strategic Resources, Department

of Commerce study of Critical Materials Requirements of the U.S. Steel

Industry. This study is a response to the Department's mandate in

PL 96-479, the National Materials and Minerals Policy, Research and

Development Act of 1980. In support of the study, the Center is arranging

a public Workshop to be held October 1982 on Trends in Critical Material

Requirements for Steels of the Future; Conservation, and Substitution

Technology for Chromium. The Center serves as alternate to Mr. R. D. Wilson,

Director of Office of Strategic Resources, in his capacity as Department

of Commerce member of the Federal Committee on Materials (COMAT) and is

supporting the Committee in its development of an inventory of Federal

Materials R&D for FY82.

Although the majority of the activities of the Center Office are reflected

through accomplishments of the Divisions, several of particular interest

merit mention here.

The Center coordinated and hosted a Briefing/Workshop on Process Control

Sensors for the Steel Industry which was cosponsored by the American Iron

and Steel Institute (AISI) and the Defense Advanced Research Projects

Agency; the workshop reviewed state-of-the-art technology pertinent to

formulating research programs that would address successful development

of process control sensors in areas identified by the AISI. It is anticipated that research necessary for development will ultimately be undertaken

cooperatively by the steel industry, universities, and government laboratories.

A Congressional ly mandated study of the costs of fracture to the U.S.

economy was completed by the Center in July 1982. Operational supervision

was by Dr. R. P. Reed of the Fracture and Deformation Division.

Center units have participated as organizer, sponsor, cosponsor, or host

for the following meetings: (1) Sixth Annual Conference on Materials

for Coal Conversion and Utilization, October 13-15, 1981; (2) Deformation,

Fracture, Wear, and Nondestructive Evaluation of Materials: Physics and

Practice, November 23-24, 1981; (3) Contact Damage in Ceramic Materials

at Elevated Temperatures, (cosponsored with the Office of Naval Research)

January 21-22, 1982; (4) Thirty-Fifth Symposium of the Mechanical Failure

Prevention Group, April 20, 1982; and (5) Seventh International Symposium on Ultrasonic Tissue Characterization (cosponsored with National Institutes

of Health) June 6-9, 1982.

560-3
Microstructure of Materials

Task 12101

Although most of the program planning and laboratory activity in the

Center takes place in the Divisions, a single task, Microstructure of

Materials, in the Center Office, takes a general view of materials

science. This task supports cutting edge theory development basic to

work in all Divisions and assures adequate attention to major new technical

challenges and opportunities, particularly those that may affect two or more Divisions. The task provides senior consultation to the Department

of Commerce and other agencies, to other NBS Centers, and to CMS Divisions,

and thus provides a window on policy study in the Executive and Legislative

Branches.

Fracture Theory

Subtask 1 of Task 12101

R. M. Thomson

A paper on dislocation screening with Sinclair has appeared in Acta Metal 1. A second paper with Lin and Weertman has been submitted to Acta Metal! . and

is now in the review process. In the second paper, the general results

on screening from the first screening paper were applied to a continuum,

one dimensional model containing an elastic enclave. These results were

then applied to fatigue crack growth in metals.

A major review has been prepared on fracture for the new edition of the

Cahn-Haasen treatise on Physical Metallurgy. This review treats fracture

in a unique way, making use of the fundamental ideas that have been

developed here at NBS over the past decade. In this review, a synthesis

has been made of the atomic mechanism at crack tips which determine

chemical effects and dislocation emission on crack growth with the

general screening theory. The general screening theory connects the

external response of the system in terms of the screening of the core crack by the dislocation field. The response of the core crack is

determined by the atomic structure of the crack tip.

Additional papers are in various stages of preparation. Two are being

prepared with Lin on application of screening theory to toughness in

metals and on the criterion for dislocation emission. Two papers have

been submitted to AIME covering liquid metal embrittlement at an upcoming

conference on the same. During this year we have also worked out the

early stages of cracks in steady-state motion and on the transformation

toughness observed in ceramics.

Theoretical Materials Stability

Subtask 2 of Task 12101

John W. Cahn

This work addresses fundamental factors in the stability of materials.

It is carried on with a wide variety of colleagues.

560-4
In support of the phase diagram activity, statistical mechanical calculations of phase equilibria and ordering in hexagonal close packed metals

are being carried out. The usefulness of various metastable curves on phase diagrams in predicting sequences of metastable equilibria and

phase change mechanism has been explored.

A symmetry theory of crystal -crystal interfaces has been developed and

applied to grain boundaries, stacking faults, antiphase boundaries, and

solid state phase transformations.

A solid-state thermodynamics theory has been developed which takes

properly into account that surface or interface stress is different from

surface or interfacial free energy and is being extended to complex

crystal structures with complex point defects.

General principles of surface, interface, and grain boundary phase

changes have been developed. One important theorem indiates that such

changes generally result in faceting to new orientations. Congruent

phase changes in which a planar surface change to a planar surface of

the same orientation with a new structure occur only for specific, and

usually highly symmetric, orientations.

Inclusion or solid precipitates in solid matrices give rise to an elastic

distortion whose energy is shape dependent. Shape bifurcations have

been shown to occur if interfacial energy is considered.

Processes Involving Conformational Changes in Polymers

Subtask 3 of Task 12101

Darrell H. Reneker, J. Mazur

The search for improved physical and mechanical properties of polymers

has led to the examination of processing methods which combine the

effects of crystallization and deformation. In this project, important

molecular scale processes associated with crystallographic defects which

are created during such processing are identified and quantitatively

modeled. The relationships between the behavior of the defects and the

macroscopic physical properties are elucidated.

Twist dispiration loops, which both rotate and translate a polymer chain, were shown [1] to provide a molecular scale model that can account for

the times associated with dielectric and mechanical relaxation processes.

Twist boundaries, composed of partial disci i nations , are boundaries where

each chain passing through the boundary twists by the same crystal

lographical ly determined amount. Twist which accumulates in a chain

during crystallization and deformation tends to persist in the chain.

Since twisted molecules cannot fit into a crystal, the twisted regions

tend to segregate into boundaries which form a template for the processes

that result in the establishment of the long period observed in polyethylene

fibers. It is necessary for the chains to diffuse along their axes in

order to bring free volume to the vicinity of the twist boundaries.

Dispiration loops, other crystal lographic defects called dislocation

loops, and, disclination loops participate in this transport process. In

order to investigate in detail the conformations and the motions of

these defects, energy calculations were performed on defect-bearing

560-5
chains inside crystals. Minimum energy conformations and the energetics

of defect interactions were determined [2].

Processing by crystallization and deformation produces lengths of straight

polymer chains interrupted by folds or other conformational defects. In

cooperative work with the University of California and the Science and

Education Administration of the Department of Agriculture, the changes

in the distribution of straight chain lengths that occur during thermal

annealing of lamellar crystals of polyethylene were measured and the

results published [3]. It was found that the distribution of chain

lengths both broadens and shifts toward longer values during annealing.

The behavior of the distribution during annealing was found to be influenced by details of the thermal and mechanical processes by which the

samples were prepared.

Molecular transport, which is an essential part of processing and crystallization, is much more complicated than diffusion in low molecular

weight fluids because of the large number of internal degrees of freedom

of polymer molecules. In collaboration with scientists in the Polymer

Science and Standards Division and the Josef Stefan Institute in Ljubljana,

Yugoslavia, magnetic resonance measurements of spin echo in a magnetic

field gradient are being used to observe the self diffusion of polyethylene

molecules in the melt. Current work suggests that polymer self diffusion

cannot be characterized by a single time independent diffusion constant.

Instead, for diffusion processes, which cover distances commensurate with

the dimensions of the polymer molecule, it is desirable to consider a diffusion coefficient which is a function of time. This time dependent

diffusion coefficient at short times is much larger than at the long

times required to transport the entire molecule. It appears the field

gradient NMR method provides a straightforward measure of the spectrum

of this time dependent diffusion coefficient.

Small differences in the energy of the various fold conformations available

to a crystallizing polymer molecule can have dramatic effects on the

morphology of the resulting polymer crystals. Calculations of the

conformational energy of folds as a function of temperature, made in

cooperation with the Polymer Science and Standards Division, are being

correlated with observed changes in the morphology of polymer crystals

prepared at various temperatures in order to find processing routes to

useful microcrystalline structures. The studies include investigations

of fold conformations in multiple fold systems on planes both transverse

and inclined with respect to the chain axis. It was found that the fold

conformations in multiple fold systems are drastically different from

the hitherto investigated single fold systems.

[1] Reneker, D. H. ; Mazur, J. Stochastic defect diffusion model for

relaxation effects in crystalline polyethylene. Polymer 23: 401;

1982.

[2] Snyder, R. G. ; Scherer, J. R. ; Reneker, D. H. ; Colson, J. P. Distribution of straight-chain lengths in unannealed and annealed solutioncrystallized polyethylene by Raman spectroscopy. Polymer 23: 1286;

1982.

[3] Reneker, D. H. ; Mazur, J. Di spirations , disci i nations , dislocations,

and chain twist in polyethylene crystals. Polymer, in press.

560-6
Other Activities of the

Office of the Center for Materials Science

Invited Talks

National Materials Policy: Critical Materials Issues and Opportunities

1981 Fall Meeting of the Metallurgical Society of AIME, Louisville, KY

J. B. Wachtman, Jr. and B. W. Steiner

October 12, 1981

The Symmetry of Martensites

1981 Fall Meeting of the Metallurgical Society of AIME, Louisville, KY

J. W. Cahn

October 12, 1981

Diffusion Induced Grain Boundary Migration

1981 Fall Meeting of the Metallurgical Society of AIME, Louisville, KY

J. W. Cahn

October 13, 1981

Advanced Materials Development: A Technical Response to the Critical

Materials Challenge

Sixth Annual Conference on Materials for Coal Conversion and Utilization,

National Bureau of Standards, Gaithersburg, MD

J. B. Wachtman, Jr.

October 13, 1981

Binary Phase Diagram Features Resulting from Higher-Order Phase

Transitions

1981 Fall Meeting of the Metallurgical Society of AIME, Louisville, KY

J. W. Cahn

October 14, 1981

Symmetry in Solid-Solid Transformation Morphologies

National Laboratory Inorganic Materials Meeting, Tsukuba, Japan

J. W. Cahn

October 20, 1981

Economic Aspects of Fracture

34th Meeting of the MFPG, Washington, DC

J. B. Wachtman, Jr.

October 21, 1981

Wetting Transitions

Metallurgical Society Meeting, Tokyo Japan

J. W. Cahn

October 23, 1981

Diffusion Induced Grain Boundary Migration

Tohoku University, Sendai, Japan

J. W. Cahn

October 27, 1981

560-7
Diffusion Induced Grain Boundary Migration

Nippon Steel, Kawasaki, Japan

J. W. Cahn

October 30, 1981

A Crack as a Defect with Implications for Fracture Resistance

1981 Fall Meeting of the Metallurgical Society of AIME, Louisville, KY

R. M. Thomson

October 1981

Symmetry in Solid-Solid Transformation Morphologies

Japanese Metallurgical Society Meeting, Kyoto, Japan

J. W. Cahn

November 3, 1981

Symmetry in Solid-Solid Transformation Morphologies

Japanese Crystallography Society Meeting

Fukuoka, Japan

J. W. Cahn

November 11, 1981

Alloy Substitution for Strategic Materials

Sixth Annual Engineering and Technical Conference, Dresser Industries,

Dallas, TX

J. B. Wachtman, Jr.

November 11, 1981

National Needs for Ceramics Research

Rutgers University, First Organizational Meeting, Center for Ceramics,

Newark, NJ

J. B. Wachtman, Jr.

November 16, 1981

Strain Field of an Inhomogeneous System

Massachusetts Institute of Technology, Cambridge, MA

W. C. Johnson

November 19, 1981

Modern Ceramics Technology

AAAS Meeting, Washington, DC

J. B. Wachtman, Jr. and S. J. Schneider

January 7, 1982

Advanced Materials Development: A Technical Response to the Critical

Materials Challenge

California State Polytechnic University, Pomona, CA

J. B. Wachtman, Jr.

January 7, 1982

The Motion of Interfaces

Georgia Institute of Technology, Atlanta, GA

J. W. Cahn

January 20, 1982

560-8
Materials Issues of Particular Current Interest to the National

Bureau of Standards and Its Programs Responding to These Issues

Commission of European Communities in Brussels, Belgium

J. B. Wachtman, Jr. and B. W. Steiner

January 26, 1982

The Materials Fracture Research Program at the National Bureau of

Standards

NBS-India Workshops on Materials Sciences and Chemical Processing,

Delhi, India and Bangalore, India

J. B. Wachtman, Jr.

February 1, 1982 and February 8, 1982

Defects in Polymers and Polymer Physics

Fraser Price Memorial Lectures (8), Polymer Science and Engineering

Department, University of Massachusetts, Amherst, MA

D. H. Reneker

February 15-26, 1982 also again April 12-23, 1982

Wetting Near Critical Points

University of Houston, Houston, TX

J. W. Cahn

February 18, 1982

Phase Transition in Metals

University of California, Santa Barbara, CA

J. W. Cahn

March 1, 1982

Interaction of a Dislocation and Precipitate

Carnegie-Mel Ion Institute, Philadelphia, PA

W. C. Johnson

March 16, 1982

Interaction of a Dislocation and Precipitate

University of Minnesota, Minneapolis, MN

W. C. Johnson

March 17, 1982

Diffusion and Phase Changes in Iron Aluminides

Wright Patterson Air Force Base, Dayton, OH

J. W. Cahn

March 24, 1982

Interaction of a Dislocation and Precipitate

Los Alamos National Laboratories, Los Alamos, NM and

University of Utah, Materials Science Department, Salt Lake City, UT

W. C. Johnson

March 1982

Interaction of a Dislocation and Precipitate

Ohio State University, Columbus, OH

W. C. Johnson

April 1, 1982

560-9
Diffusion Induced Grain Boundary Motion

General Electric, Schenectady, NY

J. W. Cahn

May 14, 1982

Thermodynamics of Surfaces

Northwestern University, Evanston, IL

J. W. Cahn

May 20, 1982

Ceramics Research at the National Bureau of Standards in Support of

Technology and Industrial Innovation

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

J. B. Wachtman, Jr.

May 14, 1982

Address to the 1982 Convocation for the College of Engineering,

Rutgers State University of New Jersey

Rutgers State University, Newark, NJ

J. B. Wachtman, Jr.

May 26, 1982

Ceramics Research at the National Bureau of Standards

Brazilian Ceramic Society, Recife, Brazil

J. B. Wachtman, Jr.

June 1, 1982

The Materials Research Program in the Center for Materials Science

of the National Bureau of Standards

CSIR, Pretoria, South Africa

J. B. Wachtman, Jr.

June 9, 1982

Advanced Materials Development: A Technological Response to the Critical

Materials Challenge

CSIR Pretoria, South Africa and Middleburg Steel Co., Johannesburg,

South Africa

J. B. Wachtman, Jr.

June 11, 1982

The Materials Fracture Research Program at the National Bureau of

Standards

University of Cape Town, Cape Town, South Africa

J. B. Wachtman, Jr.

June 14, 1982

The Materials Research Program in the Center for Materials Science

of the National Bureau of Standards

University of Witwatersrand, Johannesburg, South Africa

J. B. Wachtman, Jr.

June 15, 1982

560-10
Ceramics Research at the National Bureau of Standards

CSIR Pretoria, South Africa

J. B. Wachtman, Jr.

June 21, 1982

Origin of Long Period Chain Twist Boundaries in Polyethylene Fibers

and Their Interaction with Point Dislocations

1982 IUPAC International Symposium on Macromolecules, University of

Massachusetts, Amherst, MA

D. H. Reneker and J. Mazur

July 13, 1982

Dislocation Processes at Cracks

Gordon Conference on Ceramics

R. M. Thomson

August 1982

Twist Boundaries, Long Period, and Crystallographic Defects in Polyethylene Fibers

14th Europhysics Conference on Macromolecular Physics, Barcelona,

Spai n

D. H. Reneker and J. Mazur

September 24, 1982

Technical and Professional Committees and Leadership

Advisory Committee to the Department of Ceramic Science and

Engineering, Alfred University

J. B. Wachtman, Jr. , Member

Advisory Committee to Materials Research Laboratory, Pennsylvania

State University

J. B. Wachtman, Jr. , Member

American Ceramic Society

Rules Committee

J. B. Wachtman, Jr. , Member

American Physical Society

J. B. Wachtman, Jr., Fellow

Committee on Applications of Physics

J. B. Wachtman, Jr. , Member

American Society for Metals, International Committee for Phase

Diagrams

J. W. Cahn, Member

American Society for Testing and Materials

D. H. Reneker, Member

Applications in Physics Committee

Conference on Deformation, Fracture, and NDE, November 1981

R. M. Thomson and J. B. Wachtman, Jr.

,

Conference chairmen

560-11
Committee on Materials (COMAT)

J. B. Wachtman, Jr. , Alternate Member

Corporation Visiting Committee, Department of Materials Science and

Engineering, Massachusetts Institute of Technology

J. B. Wachtman, Jr., Member

CRC Critical Reviews in Solid State Physics

Board of Editors

D. H. Reneker, Member

Federation of Materials Societies

Committee on Materials Durability and Conservation

J. B. Wachtman, Jr., Chairman

Journal of Resource Management and Technology

B. W. Steiner, Editorial Board

Materials Research Laboratory, University of Massachusetts

Visiting Committee

D. H. Reneker, Member

Materials Coordination Task Force Department of Commerce

J. B. Wachtman, Jr., Member

National Academy of Engineering

Membership Committee

J. B. Wachtman, Jr. , Vice-Chairman

National Academy of Sciences

Solid State Sciences Committees

R. M. Thomson, Member

National Archives and Records Service

Advisory Committee on Preservation

D. H. Reneker, Member

Plastics Institute of America

Research Committee

D. H. Reneker, Member

Polymer Science and Engineering

Board of Editors

D. H. Reneker, Member

Study of Critical Materials Requirements of the U.S. Steel Industry

J. B. Wachtman, Jr. , Member of NBS team

The Metallurgical Society, American Institute of Metallurgical

Engineers

Heat Treatment Committee

J. W. Cahn, Chairman

560-12
U.S. National Committee: International Commission for Optics

B. W. Steiner, Member

Workshop on Chromium and Other Strategic Materials Needs of the

U.S. Steel Industry

Sponsors Committee

J. B. Wachtman, Jr., Chairman

Publ i cations

Cahn, J. W. ; Johnson, W. C. Chemical potentials in solids: a reprise.

Scr. Metal 1. 15: 1263; 1981.

Johnson, W. C. ; Cahn, J. W. Comment on chemical potentials in solids.

Scr. Metal 1. 15: 1259; 1981.

McCrackin, F. L. ; Mazur, J. Configuraton properties of comb branched

polymers. Macromolecules 14: 1214; 1981.

Johnson, W. C. ; Lee, J. K. An integral equation approach to the

inclusion problem of elasto-plasticity. J. Appl. Mech. 49(2): 312;

1982.

Kwon, 0

1 D . ; Beaglehold, D. ; Webb, W. W. ; Widom, B. ; Schmidt, J. W.

Cahn, J. W. ; Moldover, M. R. ; Stephenson, B. Thickness of the liquidvapor wetting layer. Phys. Rev. Lett. 48: 185; 1982.

Piccone, T. J. ; Butrymowicz, D. B. ; Newbury, D. E. ; Manning, J. R.

Cahn, J. W. Diffusion- induced grain boundary migration in the Cu-Zn

system. Scr. Metal 1. 16: 839; 1982.

Reneker, D. H. ; Mazur, J. Stochastic defect diffusion model for

relaxation effects in crystalline polyethylene. Polymer 23: 401;

1982.

Snyder, R. G. ; Scherer, J. R. ; Reneker, D. H. ; Colson, J. P. Distribution of straight-chain lengths in unannealed and annealed solutioncrystallized polyethylene by Raman spectroscopy. Polymer 23: 1286;

1982.

Thomson, R. M. ; Sinclair, J. Mechanics of cracks screened by dislocations. Acta Metal 1. 30: 1325; 1982.

Wachtman, Jr., J. B. National materials policy: critical materials and

opportunities. Am. Ceram. Soc. Bull. 61: 214; 1982.

Butrymowicz, D. B. ; Cahn, J. W. ; Manning, J. R. ; Newbury, D. E.

Piccone, T. J. Diffusion-induced grain boundary migration. Proceedings

of the 1982 international symposium on grain boundaries and interfaces

in ceramics; in press.

Cahn, J. W. ; Johnson, W. C. Where do we go from here? Proceedings of

the international conference on solid-solid phase transformation,

1981 August 10-14; Pittsburg, PA; in press.

560-13
Johnson, W. C. Interaction of a dislocation with a misfitting inhomogeneity. J. Appl. Phys. ; in press.

Johnson, W. C. ; Lee, J. K. Elastic field of inhomogeneous system.

Proceedings of the international conference on solid-solid phase

transformation, 1981 August 10-14; Pittsburg, PA; in press.

Johnson, W. C. ; Lee, J. K. An integral equation approach to the

elastic interaction of two precipitates. Phys. Status Solidi; in press.

Larche, F. ; Cahn, J. W. The effect of self-stress on diffusion in

solids. Acta Metall.; in press.

Lee, J. K. ; Johnson, W. C. Influence of transformation strain energy

upon diffusion, nucleation, and growth. Proceedings of the international conference on solid-solid phase transformation, 1981 August 10-14

Pittsburg, PA; in press.

Reneker, D. H. ; Mazur, J. Dispirations , disclinations, dislocations,

and chain twist in polyethylene crystals. Polymer; in press.

Thomson, R. M. A crack as a defect with implications for fracture

resistance. Proceedings of the 1981 fall meeting of the metallurgical

society of AIME; 1981 October 12-17; Louisville, KY; in press.

Thomson, R. M. Fracture, chapter 23 of Physical metallurgy. Cahn, R.

;

Haasen, P. , eds. New York, NY: North Holland Publishing Co.; in press.

Honors and Awards

J. W. Cahn

Fellowship Japan Society for Promotion of Science

October 1981

560-14
MATERIALS CHEMISTRY DIVISION (561)

Thomas D. Coyle, Chief

Samuel J. Schneider, Deputy Chief

Lillian L. Ware, Secretary

Within the overall program of the Center for Materials Science (CMS), the

Materials Chemistry Division provides a focus for research and measurement

activities which are fundamental to understanding the chemical stability

and reactivity of materials in processing and use. The Division provides

data, conceptual understanding, measurement methods, standards, and refer- ence materials which find broad application in scientific and engineering

activities of industry, other Government agencies, and scientific organizations.

The intrinsic chemistry of materials, and their reactivity with their

environment, are critical to processing and to performance and durability

in service. The requirements of advanced technology in areas such as transportation, energy, and aerospace for materials that will function

at higher temperatures in aggressive environments demand chemically robust

materials and the means to assess their performance and extend their

service life. National concerns for critical and strategic materials

require improved basic understanding of chemical durability to support

design and selection of substitutes. Understanding of the chemical reac- tivity of materials and their degradation products is also critically

important to assessing and minimizing the environmental impact of materials

processing and use.

The Division's program is broad, in the sense that it addresses chemical

aspects of processing, durability, and use of a wide range of materials

including metals, ceramics, glass, and polymers. It is tightly focused

in the sense that it addresses common problems of chemical behavior of

these diverse classes of materials.

The research thrusts of the Division include the following activities:

(1) Determination of the chemical durability of materials and the mechanisms of degradation, including corrosion and degradation of metals,

ceramics, and special-purpose polymeric materials, and chemical aspects

of tribology.

(2) Investigations of the basic chemical phenomena underlying materials

processing, including ceramic processing, and production of protective

metallic and ceramic coatings.

(3) Determination of basic mechanisms and measurement methods to control

and minimize adverse environmental impact of materials processing and

use.

(4) Development of methods for structural and chemical characterization

of materials, degradation products, and process intermediates required

to support (1) through (3).

561-3
The Division carries out numerous cooperative programs with the private

sector and with other Government agencies, providing often unique services

to these groups while maintaining the focus of the Division on problems

of current technological concern. A long-standing program with the American

Iron and Steel Institute (AISI) on corrosion protection of marine pilings

was completed this year; the results will provide essential design information for corrosion protection of offshore structures. A joint program

with the American Electroplaters 1 Society (AES) to study new pulsed electrodeposition techniques for producing corrosion resistant alloy coatings

has led to new methodology which has the potential for reducing the use of critical alloying elements. A Research Associate program with Mobil

Oil has led to development of methods to identify and measure arsenic

compounds in shale oil, critical to protection of process catalysts in

this area of synthetic fuel technology. Cooperative programs with more

than a dozen companies in the petroleum industry have established a basis

for quality control assessments of lubricants and oxidation stability.

Joint programs with other agencies provide critically needed data and

measurement methods. We have developed for the Federal Highway Administration (FHA) a field instrument to measure corrosion of reinforcing bars

in concrete bridge decks. Our research supports the development of new

anti foul ant coating technology for the U.S. Navy and provides the measure- ment methods needed to enable the Navy to address environmental impact

of this new development. Our ceramic sciences program provides, for

example, fluorescence standards to the U.S. Postal Service, data on the

properties of structural ceramics for the Department of Energy (DOE),

and ceramic processing methodology essential to the development of temperature and oxygen measurement sensors for high temperature applications in

steel and energy technologies. Our Glass Group provides tailored glasses

for DOE applications in laser fusion research and to support the Department

of Defense (DOD) requirements for fiber-optic sensors.

The Division's outputs include major activities in the area of evaluated

standard reference data, including production with the American Ceramic

Society (ACerS) of the widely-used Phase Diagrams for Ceramists. In FY82,

major efforts were made to expand this activity, develop increased industrial support in conjunction with ACerS, and automate the operations of

the Phase Diagrams for Ceramists Data Center. A continuing research asso- ciate program with the Joint Committee on Powder Diffraction Standards

produces standard x-ray powder patterns, and major advances have been

made in application of computer techniques for profile analysis and quantitative x-ray powder diffraction analysis. A third data activity has

led to completion of a major volume on materials performance data in coal

conversion systems.

Production of Standard Reference Materials (SRM) is another major Division

activity. We produce 5000 SRM units annually for calibration of coating

thickness measurement instrumentation in support of the metals, coatings,

and electronics industries. Our dye-penetrant crack SRM, produced by

the Electrodeposition Group, is required by the Federal Aviation Administration (FAA) as a basis for inspection of aircraft components. Other

SRMs include standards for qualitative and quantitative x-ray diffraction analysis, property standards for control of processing in the glass

industry, and compositional standards for particulate and surface analysis.

561-4
1

The present structure of CMS places the major NBS responsibility for

ceramic sciences activities in the Division. Accordingly, Division management has undertaken a thorough-going review of our ceramic programs in the

context of current thrusts in ceramic sciences and technical and industrial

needs. The Division has instituted a systematic series of contacts with

the industry, a cooperative assessment of economic and technical aspects

of advanced ceramic technology (in cooperation with the NBS Planning

Office and the Fracture and Deformation Division), and a formal ceramic

program planning activity to determine the directions of future NBS efforts

in ceramics and glass.

The research activities of the Division, and its recent technical accom- plishments, are described in the following pages. For management purposes,

the technical program is divided into task areas, as follows:

Task 12113— CORROSION AND PROTECTION OF METALS. Concerned with the

mechanistic and environmental parameters controlling metallic corrosion and the electrodeposition of coatings; major emphasis on corrosion measurement and detection, mechanisms of localized corrosion

such as crevice corrosion, stress corrosion cracking, hydrogen

embrittlement, development of SRMs for coatings, and processing

science related to coating technology.

Task 12114—MATERIALS BIOTRANSFORMATIONS AND CHEMICAL DURABILITY IN

SERVICE ENVIRONMENTS. Involves the mechanistic behavior of materials

degradation in their service environments, particularly that related

to chemical and biological initiated reactions. Major thrusts directed

toward microbial corrosion and to the key transport or diagnostic

chemical species which define pathways to chemical and biological

transformations of materials in service environments.

Task 12115— HIGH TEMPERATURE MATERIALS CHEMISTRY FOR PROCESSING AND

DURABILITY. Relates to the thermodynamic and kinetic behavior of

materials in aggressive service environments at high temperatures and

pressures. Major work directed toward phase equilibria of ceramic/

glass systems through modeling and experiment. In cooperation with

the American Ceramic Society the widely-used Phase Diagrams for

Ceramists, is compiled and edited through the data activities within

this Task.

Task 12154- -PROPERTIES , STRUCTURE, AND STANDARDS FOR GLASS AND OPTICAL

MATERIALS. Concerned with the processes involved in the synthesis,

forming, and uses of glass and optical materials, including thin films.

Major activities are devoted to the development of SRMs needed by the

glass industry and others such as those for viscosity, resistivity,

dielectric constant, thermal expansion, and chemical -analytical purposes; optical properties of glass; and process-structure-property

relationships in thin films of glasses and ceramics.

Task 12156— CERAMIC PROCESSING AND DURABILITY SCIENCE. Involves chemical and physical processes influential in producing reliable and

durable ceramics. Particular emphasis on establishing controlling

materials parameters throughout the ceramic processing cycle. Major

activities are devoted to powder and compact characterization by

561-5
x-ray methods and electron microscopy and structural chemistry aspects

at ambient and high pressures and temperatures. X-ray SRMs and

standard data are significant products.

Task RECYCLED OIL PROGRAM. Concerned with the development of

data base and test methodology for the NBS Recycled Oil Program.

Major emphasis on chemical stability of complex organic mixtures at

metal-lubricant surfaces, reaction kinetics in condensed phase systems,

tribology and tribochemi stry , and chemical characterization of lubricant and fuels.

FY82 Significant Accomplishments

Task 12113— CORROSION AND PROTECTION OF METALS.

• Successful use of a new surface EXAFS technique to demonstrate the

noncrystalline structure of the passive film formed on iron in a chromate passivating solution.

• Successful application of the electrochemical corrosion measurement

techniques developed by the Corrosion Group to in-service copper con- centric neutral cables in Baltimore, MD.

• Sixty-eight steel piles exposed for thirteen years to an offshore

seawater environment have been removed and evaluated for corrosion

damage. These data are being correlated with data obtained during

exposure using electrochemical techniques.

• An instrumented probe designed to simulate heat exchange steam pipes

in a refuse burning incinerator has been installed at the NASA- Langley

incinerator facility allowing data to be obtained on the corrosion

performance of five alloys.

• Techniques have been developed to separate pitting and crevice corrosion phenomena, including an ability to initiate pits in 5 to 60 s that simulate those that develop over months and possibly years.

This allows one to determine corrosion rates and study the kinetics

of the two systems separately.

• A technique has been developed which allows effective simulation of

corrosion processes under organic coatings, leading to design of more effective corrosion control strategies.

• Alloys of nickel containing up to 60 wt. % chromium were produced

using a new process developed by the Electrodeposition Group. These

coatings can be formed in thick layers. Corrosion and wear performance, along with deposition mechanisms, are currently under study.

• Two new microhardness standard reference materials in the range of

100 khn and 500 khn have been developed. These standards exhibit

significantly improved uniformity of hardness over currently available non-NBS standards.

561-6
Task 12114—MATERIALS BIOTRANSFORMATIONS AND CHEMICAL DURABILITY IN

SERVICE ENVIRONMENTS.

• Development of measurement methods and preliminary data supporting

a new mechanism of anaerobic biocorrosion of bulk iron. This will

provide diagnostics for economically significant biocorrosion and

permit design of more effective corrosion control.

• Incorporation of complementary molecule-specific characterization

methods into Mil -Spec development for Navy's major procurement of

fleet antifoulant polymers.

• Demonstration of theoretical basis for correlating molecular conformations and shapes to liquid chromatography separations and NMR

spectra. This provides a significant new tool for characterization

of degradation products and determination of corrosion mechanisms.

• Characterization of a mercury-reducing enzyme imparting toxic metal

resistance in bacteria crucial to bioleaching technology for copper

mining.

• Demonstration of the concentration of organotin biocide residues in

marine surface water microlayers as a key component in their environmental fate.

• The Mobil Research and Development Corp. has established a research

associate program in the Materials Chemistry Division dedicated to

ultratrace speciation of arsenic in industrial shale oils and process

waters. This work will extend to shale oils the element-specific

molecular characterization methods developed by the Chemical and

Biodegradation Processes Group.

Task 12115— HIGH TEMPERATURE MATERIALS CHEMISTRY FOR PROCESSING AND

DURABILITY

• Volume IV of Phase Diagrams for Ceramists, containing 570 critically

evaluated new diagrams of metal -oxygen, metal -oxide, and oxygencontaining radical type systems, was published by the American Ceramic

Society. Final editing of Volume V, containing about 750 new diagrams

of halide, sulfide, oxynitride, aqueous, and ceramic-gas systems was substantially completed.

• A new theory for mixing of complex liquid and solid phases has been

developed and validated (by comparison with experimental activity and

phase equilibria data) for representative ceramic, slag, and glass

systems containing K2 0, CaO, A1 2 0 3 , and Si

0

2 ; and molten salt systems

containing PbC 1 2 , CsCl , PbBr2 , NaBr, KBr, and CdCl 2.

• Reactions between HC1 -containing gases and glass or dolomite substrates, leading to alkali vapor transport have been shown to be

highly rate limited. This indicates that chemical kinetic factors

must be included in current thermodynamic modeling efforts for the

prediction of alkali vapor transport in coal conversion/combustion

systems.

561-7
• The effect of particle size on sintering properties (density and

strength) of potassium and calcium aluminosilicate phases has been

determined, leading to a new synthesis of refractory ceramics with

improved density and strength.

• The "continuous" phase transition in ZrTi04 , an important microwave

dielectric, was characterized and single crystals containing no superstructure, an incommensurate superstructure, and a commensurate

tripled cell were synthesized using various fluxes.

Task 12154--PR0PERTIES, STRUCTURE, AND STANDARDS FOR GLASS AND OPTICAL

MATERIALS

• Using the unique thin film facility at NBS, it has been demonstrated

that microstructure of Zr0 2 films, important as optical coatings,

can be modified by vapor codeposition processing incorporating MgO

or Si0 2. By control of deposit composition and process temperature,

amorphous films can be obtained, eliminating grain boundaries potentially deleterious to the durability of coatings.

• Six techniques have been compared for measuring thin films of ~ 1 pm

thickness: stylus profiling, dual beam interferometry, multiple beam

interferometry, prism-coupler method, ellipsometry, and channeled

spectra; they are found to be of comparable accuracy. The prism

coupler method has been used also to obtain accurate refractive index

and dispersion data for a mixed Mg0-Si02 film. Because of the high

precision of this method, estimates of the internal stress in films

are possible.

• In collaboration with Stanford University, recent work showed that

i n situ observations of phase separation in the Ba0-K2 0-Si02 system

could be monitored by time-resolved small-angle x-ray scattering

technique and a high energy (Synchrotron) source.

• Activities leading to the certification of a dielectric constant

glass standard (SRM 774) have been completed. This work involved

the completion of interlaboratory comparison with industrial laboratories, statistical analysis of data, test methods and procedure

improvements, sample preparation for SRM packaging, and issuance of

SRM certificate.

• A series of silicate glasses (containing alumina, alkaline earths,

and tantalum oxide) have been prepared that have both unusually high

Young's modulus (E > 1.1 x 10 12 dyn/cm2

) and as unusually low linear

thermal expansion coefficient (a < 3 x 10“6 /K at 20 °C). The two

properties make these glasses highly desirable for the production of

pressure insensitive optic fibers.

Task 12156— CERAMIC PROCESSING AND DURABILITY SCIENCE

• Application of digital data collection and x-ray line profile refinement for powdered materials was a major accomplishment. Accuracy in

measurement of 26 was demonstrated to be ~ 0.03°, which is three to

561-8
five times better than the average error associated with strip chart

recording methods. The profile model developed was shown to be

superior to existing functions normally applied.

• The structures of amorphous/glassy materials were determined at elevated pressure for the first time using a radial distribution function analysis technique and the diamond anvil pressure cell.

• YCr03 -based, sintered ceramics were specially processed for a unique

NDE study. A phase transition associated with a small volume change

appears to occur near 1100 °C. This transition induces microcracks

that heal and reopen with appropriate anneals. The material serves

as a model ceramic for elasticity and small -angle neutron scattering

(SANS) measurements to detect microflaws.

• It has been shown that unlike pure A1 2 0 3 , powders containing Cr2 0 3

in solid solution nucleate a considerable volume fraction of the

stable or form when plasma sprayed. Such ceramic coatings on Mosubstrates are adherent, and preliminary tests indicate excellent

corrosion/erosion resistance in molten iron 1550 °C).

• Two instrument 26 calibration standards have been certified: silicon

powder (SRM 640A) and fl uorophlogopite powder (SRM 675). The latter

is a low 26/large d-spacing standard.

• A major handbook, Construction Materials for Coal Conversion—Perfor- mance and Properties Data has been completed. It contains some 800 pages of evaluated corrosion, erosion, and mechanical property

data for metals and ceramics tested under coal conversion conditions.

Task RECYCLED OIL PROGRAM

• A gel permeation chromatography-graphite furnace atomic absorption

apparatus was built to study the role of organometal 1 ic reactions in

wear contacts. Organic iron compounds formed as a result of wear

were associated mainly with high molecular weight oxidized hydrocarbon

structures (1,000 to 100,000 MW), were shown to be formed in wear

processes—a major advance in understanding of tribochemical processes.

• Significant advances were made in the area of separation science of

complex organic mixtures. A novel separation method was developed

using neutral activated alumina column and selected solvent systems

to separate the naturally occurring polar molecules in fuels and lubricating base oils into their molecular compound classes.

• Two cooperative studies with industry were conducted: (1) An NBS/

ASTM basestock consistency program was successfully concluded.

Monthly production samples of lubricating base oils were received

from 10 refineries (6 re-refined, 4 virgin base oils). Fourteen

i ndustrial /government laboratories participated in analyzing these

base oils for consistency and performance. (2) A program involving

11 companies was initiated to study the effects of base oil composition on oxidation stability with additives. Over 100 base oils from

10 crude sources were supplied by the companies with analytical data.

561-9

1

CORROSION AND PROTECTION OF METALS

Task 12113

The activities of the Corrosion and Protection of Metals Task are aimed

ultimately at reducing the severe economic losses resulting from corrosion.

They are concerned with both measurement methodology and establishing the

scientific base necessary to support such endeavors. Thus the work carried

out includes basic studies of the mechanisms of specific corrosion and

electrodeposition processes; the development and evaluation of test methods,

both in the laboratory and in the field; the generation of specialized

corrosion data; and the development of SRMs. The work is carried out under

two subtasks, one dealing with corrosion and one with electrodeposition.

Much of the work in the corrosion subtask is focused on localized corrosion, namely, pitting, crevice corrosion, stress-corrosion cracking, and

hydrogen embrittlement. Each of these commonly encountered forms of

localized attack involves the breakdown of the protective surface films

which normally impart corrosion resistance to engineering alloys. The

so-called passive films of the type found on stainless steels are of particular commercial importance, and their structure and breakdown received

continued attention during FY82.

The electrodeposition subtask is important to metals processing technology

for the production of economical and energy efficient materials and coatings

which are unusually resistant to corrosion and wear. Improvement of coatings

to enhance the corrosion and the wear resistance of alloys is a major element

in strategies to reduce dependence of U.S. industry on critical materials

such as chromium. This subtask seeks to develop new understanding of the

properties and structures of electrodeposition processes, to improve cur- rent electrodeposition technology, to produce and develop SRMs that are necessary for the measurement technology widely used by the coatings industry, and to devise new SRMs, requiring electrodeposition for their

fabrication, for use in nondestructive evaluation techniques and for instrument calibration.

The technical activities carried out under each subtask are described below.

Corrosi on Subtask 1 of Task 12113

J. Kruger, N. K. Adams, U. Bertocci , T. Cassagne 1

, E. Escalante, J. L. Fink,

J. L. Mullen, E. N. Pugh, K. A. Rhyne, J. J. Ritter, M. J. Rodriguez,

G. Rondelli 2

, B. T. Sanderson, P. W. Slattery3, J. Smit, D. K. Tanaka4

, F. Thomas, Mingda Wu 5

, Yang-Xiang Ye 6

1 Guest Worker from "Compiegne" University of Technology, Angouleme, France

2 Guest Worker from C.N.R. Laboratorio per la Technologia dei Material

Metallici non Tradi zional i , Cinisello (Milan), Italy

3 Guest Worker from South Australian Institute of Technology, Adelaide

4 Guest Worker from Technological Research Institute of Sao Paulo, Brazil

5 Guest Worker from Shanghai Research Institute of Materials, Shanghai,

People's Republic of China

6 Guest Worker from Wuhan Research Institute of Materials Protection, Hankou,

People's Republic of China

561-11
Passive Film Properties

The breakdown of passive films is an important factor in localized

corrosion. One approach to the study of film breakdown involves the

analysis of electrochemical noise. This new method promises to provide

a research and measurement technique for monitoring pitting in critical

components, and to give fundamental insight into the pitting process

itself. In these studies, three Fe-Cr alloys of different Cr content

were held under potentiostatic conditions in the presence and absence of

pitti ng-i nduci ng chloride ions, and the amplitude and frequency content

of the current fluctuations were examined. In the absence of the chlorides,

no current fluctuations were detected for any of the alloys. This is an important observation in itself, since it suggests that the film does

not undergo breakdown, in contrast to a widely held view that random

breakdown always occurs and that the occurrence of pitting depends on whether repassivation takes place. Thus the present work suggests that

the most important role of the aggressive anions is in increasing the

chance of local film breakdown rather than affecting the repassivation

rate.

In the presence of chloride ions in solution, random spikes in the

current, as shown in figure la, were observed during the induction

period. The corresponding spectra were in general flat, confirming that

the current transients have decay times shorter than 10 ms. Once a pit

started growing, the current increased in a roughly linear fashion,

becoming progressively noisier. The spectra taken during pit growth

show decreasing amplitude with frequency, often exhibiting two different

slopes on a logarithmic plot. Examination of the slope of the spectra

suggests that the repassivation of the exposed areas is a complex process

and not a simple exponential decay of the active current. Guest Worker

Y. Ye participated in this work.

The observation of time series such as those shown in figure la raised

the question of whether their statistical analysis would be useful for

the construction of models, leading perhaps to a mechanistic interpretation of the random current fluctuations. Finding a suitable statistical

model to describe the fluctuations before and during pitting, as well as

in other corrosion situations, would also help in deciding which of the

possible spectral estimation techniques is more appropriate. Since

other workers in the field of corrosion noise have recently proposed the

use of the maximum entropy spectral analysis (MESA) method as more suitable than the Fourier transform method, an examination of this issue

appears necessary.

Exploratory work aimed at finding out whether a moving average or an autoregressive statistical model better fits the experimental time

series was conducted in cooperation with S. D. Leigh of the Center for

Applied Mathematics. Also, computer programs were prepared for the

purpose of comparing different spectral estimation techniques. Very

simple mechanistic models were formulated, so as to generate time series

of random fluctuations to be used for statistical modeling. For instance,

figure lb derived from a model based on the assumption of randomly

occurring active areas on a passive electrode, which then repassivate

according to various time functions, can predict fluctuations very

561-12
similar to those shown in figure la. Testing of such models was initiated.

Computer simulations were also used to study the effects of the measurement

techniques on the statistical structure of the experimental data.

Three other studies of the passive film on iron and ferrous alloys were initiated during the year. The first was directed at gaining an understanding of a new treatment for Type 304 stainless steel which has been

claimed to produce a more resistant passive film. This is a particularly

intriguing possibility since Type 304 steel is the workhorse of corrosion

resistant materials, despite its propensity to localized corrosion.

According to a recent report from the Shanghai Research Institute of

Materials, this improvement was obtained by anodizing the steel in

dilute sulfuric acid in the transpassive region. The precise details were

not available, but a general study was made of the growth of anodized

films in the transpassive region, primarily using ellipsometry and

impedance techniques. Guest Worker G. Rondelli collaborated in these

studies. The results indicated that drastic changes in the optical and

electrical properties occur in a very narrow potential range. In the

potential region where anodization is supposed to improve corrosion

resistance, it was found that a thickening of the oxide film occurs. However, the ac impedance results point to an increase in corrosion

resistance due to a slowing of the charge-transfer resistance rather

than to a film thickening. Capacitance increases can be interpreted as due to adsorption of ions, perhaps hexavalent Cr. It should be noted

that surface analyses carried out on the anodized film showed a ten-fold

enrichment in Cr as compared with the bulk metal.

The second study is concerned with the structure and nature of the passive

film on iron. It is a collaborative research effort with G. G. Cohen and

M. Kuriyama of the Metallurgy Division and seeks to provide structural and

compositional information on passive films on iron and the changes that

take place in these films during breakdown. This information is of great

importance to our understanding of all localized corrosion processes which

usually involve as a first step the breakdown of passivity. This collaborative study involves a new and very sensitive surface, extended x-ray

absorption fine structure (EXAFS), technique developed by NBS. During the

year, this work has revealed that the passive films formed on iron exposed

to chromate and nitrate passivating solutions have higher percentages of

covalent bonding, especially the chromate, and have structures different

from the known crystalline iron oxides or oxyhydroxides. Around 12 percent

of chromium, a glass former, was found in the films formed in chromate

which were more glassy than the films formed in the nitrate solution.

The third study on passivity concerns the formation and breakdown of

passive films on steel in ethanol, a problem of importance to the use of

ethanol as a motor vehicle fuel. This work is a collaborative effort

between Guest Worker D. K. Tanaka and Division 561 personnel. Its main

approach has been to use el 1 ipsometric measurements to follow passive

film formation and breakdown. This is necessary because electrochemical

measurements are not very useful in the low conductivity ethanol solutions.

Electrochemical noise measurements were also carried out. The studies

have shown that only slow oxide film growth is observed in 95 percent

ethanol in the presence or absence of chloride ions. Only when a low

561-13
level of contaminants, such as an acid (H2 S0 4 ), is present does dissolution of the air-formed film and roughening of the surface occur.

Pitting and Crevice Corrosion

Pitting corrosion involves both the initiation and growth of pits. The

studies described above have focused primarily on the initiation stage,

i.e., film breakdown, and on the nature of the film. In another major

effort, attention was directed to the growth stage, specifically to the

determination of quantitative values of pit growth rates as a function

of potential and temperature. In addition to obtaining a better understanding of the growth mechanism, our interests here are on long-term

prediction and accelerated testing, currently a special concern of a number of critical technologies such as the development of reliable

systems for the storage of nuclear wastes. Guest Worker M. Wu collaborated in these studies, which were carried out on Type 304 stainless

steel in 3.5% NaCl solution, a system in which localized corrosion

occurs readily.

To study the growth process, it was first necessary to reduce the incubation period for pit initiation, usually quite long. Other workers have

achieved this by laser damage or drilling, but this is not thought to

simulate normal pit initiation. Thus, an electrochemical technique was developed for this purpose. First it was necessary to determine the

pitting potential, E , below which pits are not initiated, and the

protection potential, Ep rot » below which pits, once initiated, no longer

propagate. This was achieved by cyclic potentiodynamic methods. Once

these potentials were established, pits were initiated potentiostatical ly

by rapidly increasing the potential above E , and the potential was then

rapidly reduced to a value between Ep rot

and E , permitting the pits to

grow. (Note that Ep rot = E^.) This procedure, which has now been

adopted at Brookhaven National Laboratory (BNL) and by other groups,

allows one to initiate pits in 5 to 60 s with similar chemical and

mechanical properties to those of naturally occurring pits that take

months and years to form. The growth of the pits was studied by monitoring

the current as a function of time in the potentiostatic tests. Several

potentials and several temperatures in the range 0 to 45 °C have been

studied so far. Interestingly, the preliminary results indicate that

the pit growth rates are greater at 25 °C than at either 0 °C or 45 °C.

I

These studies are being extended to crevice corrosion, a process which"

also involves the breakdown and repair of the passive film and which is

commonly believed to be closely similar to pit growth. A specimen

configuration has been developed and initial tests are in progress.

Tests will be conducted at the same potentials and temperatures as in

the pit growth experiments, permitting direct comparison.

Stress-Corrosion Cracking

Another major effort involves stress-corrosion cracking (SCC). In this

case, the passive or protective films are broken by stress, permitting

the environment to interact directly with the underlying metal. The

561-14
nature of the interaction which leads to cracking remains poorly understood,

despite the fact that SCC continues to limit the performance of virtually

all engineering alloys. Effort is divided into the development and

evaluation of test methods to determine SCC susceptibility and studies

of the basic mechanisms of failure. In the former, further attention

has been given to the load-pulsing technique for measuring the velocity

of stress-corrosion cracks. In this method, small load pulses are periodically applied to a specimen undergoing cracking under an otherwise

constant tensile load. The pulses cause limited crack blunting which

produces markings on the resulting fracture surfaces, corresponding to

the successive position of the crack front; the crack velocity is obtained

from the spacing between the markings and the time interval, At, between

pulses. This method offers a convenient and inexpensive way to obtain

crack velocities. However, it is important to demonstrate that the

pulses do not influence the velocity. In our earlier work on Type 310

austenitic stainless steel in an aqueous chloride solution, it was shown

that the Stage II velocity, i.e., corresponding to the stress-independent

region of the velocity-stress intensity relationship, was independent of

the magnitude of At over a wide range of values. Over the past year,

Guest Worker P. W. Slattery and Division 561 personnel extended these

studies to the transgranul ar SCC of Admiralty Metal in aqueous ammonia,

a system of considerable practical importance, e.g., the failure of

condenser tubes. Again the Stage II crack velocity was found to be

constant for a wide range of values of At, figure 2. The velocity can

be seen to increase progressively as At decreases below ^ 100 s, and

this is considered to result from a fatigue contribution to crack extension.

The constant value, ~ 2 x 10 -7 nrs

-1

, is in good agreement with those

obtained by conventional methods. It is planned to extend this method

to studies of the effect of temperature on crack velocity.

The mechanistic studies have been focused on copper and alpha-phase

copper alloys. The failure of Admiralty Metal and Cu-30Zn in aqueous

ammonia is of particular interest mechanistically because of the ongoing

debate on the role of hydrogen in SCC. Because of the relative mobility

of the brasses and the high pH of the ammoniacal solutions, hence a low

reversible hydrogen potential, it appears that hydrogen absorption can

be ruled out in this system, and, because of similar characteristics, in

other important alloys, e.g., austenitic stainless steels. The apparent

elimination of a hydrogen model has led to a search for alternative

mechanisms. Selective dissolution of zinc has been proposed and much of our effort over the past year has been directed to the evaluation of

this possibility for the case of transgranul ar SCC, shown by our earlier

work to involve discontinuous cleavage. It has been proposed that

dezincifi cation at the crack tip leads to vacancy injection and that

resulting vacancy-dislocation interaction in the plastic zinc permits

limited cleavage to occur. To test the feasibility of this proposal,

attempts have been made to simulate the proposed crack-tip conditions in

purely mechanical tests. Specifically, severely cold worked Cu-30 Zn

specimens both poly- and monocrystalline, have been annealed at temperatures below that required to cause recrystallization, permitting various

amounts of recovery, a process known to involve vacancy-dislocation

interaction; the specimens were then fractured by impact in room temperature air. In other tests, severely cold worked monocrystals were strained

to failure at slow strain rates at various temperatures below the recrystallization temperature in dry argon gas. No cleavage was produced in

561-15
either set of tests, all specimens failing entirely by ductile processes.

Interest in the possible role of dezi nci fi cation led us to continue our studies of the cracking of pure copper in aqueous sodium nitrite.

Extensive efforts, again involving Guest Worker P. W. Slattery, failed

to substantiate the report by other workers that cleavage-like SCC can occur in the pure metal. Thus, despite the absence of direct experimental support, the dealloying hypothesis cannot be eliminated as a possible mechanism.

An important development during FY82 was the initiation of a program to

mathematically model the environmental conditions within cracks and

crevices. This activity began with a study of cracks in the brass-ammonia

system, and supported the view that the potential and pH at the crack

tip cannot permit hydrogen absorption. These studies are being extended

to crevices in iron in caustic solutions, and it is anticipated that the

modeling will be followed by experimental studies.

Corrosion Processes Under Protective Coatings

The studies of the local chemistry in cracks and crevices relate directly

to our on-going investigation of the corrosion of painted metals. This

program, partially supported by the Office of Naval Research (ONR), has

focused on the micro-environment that forms under paints and the passive

film formation and breakdown processes that occur in this environment.

Besides its contribution to a better understanding of localized corrosion,

this project also develops techniques that contribute to the development

of more effective corrosion protection by improved organic coatings.

Two approaches have been taken in the investigation of corrosion on painted metals: (1) detection and analysis of subcoating phenomena

during corrosion; and (2) an elucidation of the subcoating chemistry

responsible for these phenomena. In the first, i_n situ el 1 ipsometricelectrochemical studies of corrosion of iron and steel protected by

organic coatings have been continued. While earlier work treated only

the iron/cellulose nitrate system, more recent investigations have

included both iron and steel coated with other materials such as polybutadiene and proprietary acrylic lacquers. El 1 ipsometric responses for

specimens undergoing corrosion were quite different for coatings cured

at room temperature and those cured at elevated temperatures. An automated

el 1 ipsometric system developed for this work provides optical data in

much greater detail than possible heretofore. Our interpretation of

these new data shows, for the first time, the temporal evolution of

subcoating events for the cathodic coating delamination process. These

results are summarized graphically in figure 3. In the previous report

we speculated that "... changes in the nature of the metal surface

'oxide' films . . . can result in bond fracture." The new results

clearly show a thinning of the surface "oxide" as the first step in the

subcoating events as corrosion propagates. For the systems studied, we propose that dissolution of the oxide film to which the coating is

bonded is the predominant mode by which coating delamination occurs. Dissolution of air-formed surface "oxide" films in strong NaOH solution

(i.e., a simulated subcoating environment) can be demonstrated independently. The subsequent subcoating events of surface roughening and

oxide film thickening are consequences of the dissolution of exposed

561-16
1

metal in strong base and the barrier properties of the delaminated

coating, respectively. While the above interpretation applies to coatings

cured at room temperature, the el 1 ipsometric responses for coatings

cured at elevated temperatures are more complex and are still under

analysis.

In the second approach to this problem, a new method for investigating

subco'ating chemistry has been initiated. A technique which simulates

the subcoating corrosion system in the generation of segregated anodes

and cathodes has been developed. Preliminary investigations of the

chemistry of the anolyte and catholyte indicate the buildup of chloride

ions at the anode and high levels of sodium and hydroxyl ions at the

cathode. The results are consistent with measurements made on actual

subcoating liquids.

Test Methods and Corrosion Data for Specific Practical Applications

Work in this area in FY82 has emphasized such diverse but technologically

important environments as soils, the sea, waste incinerators, and concrete

bridge decks. Significant technical activities during FY82 in have been

the following:

(1) The ever-increasing use of buried electric power cables has been

plagued by unexpected corrosion problems. Such problems require measurement techniques that allow power company personnel to detect and measure

the corrosion of cables without excavation. The Electric Power Research

Institute (EPRI) has asked NBS to develop such i_n situ measurement

techniques. This project has been directed in the past year toward

field measurements of cables in service and completion of the microprocessor system. The limited number of measurements at four sites in

Baltimore, MD, revealed that the corrosion rates measured undergo considerable change with time, making it difficult to clearly identify any

given area of cable as a high corrosion area. For purposes of this

study it was considered prudent to increase the number of measurements

thereby improving the statistical confidence of the results prior to

excavation of the cables for verification of our measurements. In

addition, three new sites in Baltimore have been identified as high

corrosion areas and are now included in our study. The data gathered

indicate that the corrosion observed is not generally related to the

resistivity of the soil. Of the two original sites identified as suspected

of being highly corrosive, our measurements indicate that one of these

generally does display high corrosion rates as compared to the other

sites. At the second area suspected of having a high corrosion rate, our measurements indicate that the rate does vary considerably with

time. The two low corrosion sites do, in general, indicate low corrosion

rates as indicated by our measurements. In all cases, the electrochemical

polarization measurements are carried out without any significant ac interference. The length of cable undergoing polarization is 5 to 7 meters

long with the counter electrode 1 meter from the cable.

(2) The study on the corrosion of metals and alloys used or under

consideration for use in waste-to-energy systems supported by the Department of Energy and the Department of Defense was continued. This study

is directed toward corrosion problems that may exist in incinerator

561-17
systems where refuse-derived fuels are burned. During this year a corrosion probe has been developed and installed at the NASA-Langley

incinerator facility in Hampton, VA. This probe (see fig. 4) is air

cooled to simulate the surface temperatures of the steam boiler heat

exchange tubes, and exposes five ferrous alloys used in incinerators.

Four thermocouples are located along the length of the probe providing

information to a controller regulating an air valve which controls a flow of air through the probe maintaining it at some preset temperature.

The five ferrous alloys are in the form of 1 in. dia. , 1 in. long tube

specimens which can easily be removed or replaced for inspection. The

data indicate that the temperature of the probe can fluctuate from 300°

to 750 °F. This is a much wider change than expected. Specimens from

this probe were removed for inspection during July. A second probe was also installed at the Wright-Patterson Air Force Base incinerator.

(3) The final phases of an American Iron and Steel Institute sponsored

investigation of the effectiveness of corrosion protection of steel

piling in seawater by a variety of systems and of methods for evaluating

the degree of protection with time were carried out during the past

year. Sixty- two H-piles and 6 pipe piles each 35 feet long and weighing

almost 1 ton were shipped to Bath, PA, for sandblasting prior to our

physical measurements used for evaluating the degree of corrosion deterioration suffered during their 13-year exposure to an off- land ocean

environment. The preliminary evaluation revealed that the sacrificial

anodes had reduced the extent of erosion damage at the sand/water interface, a region which is otherwise extensively attacked. The large mass

of data gathered this year and in years past are now under analysis.

The results of this study will provide important engineering data for

the design of offshore structures.

Four pilings were extracted the previous year from the underground test

site in Montreal, Canada. Three of these piles were removed from their

vertical position where they had been driven 12 years before. The

fourth pile was removed from a horizontal position approximately six

feet below ground. Analysis of the corrosion data clearly indicates

that the horizontal pile underwent severe corrosion as compared to the

vertical piles. One of the vertical piles was capped with concrete

during the exposure period. Some corrosion did develop below the concrete

cap but was not as extensive as that which was found at the ground water

line. These data too are undergoing further analysis.

(4) An increase in underground telephone cable installation by the

telephone industry throughout the United States has created a demand for

comprehensive and reliable information with respect to the corrosion of

shielding materials. In order to obtain such corrosion data on both

currently accepted and proposed experimental cable systems, the National

Bureau of Standards and the Rural Electrification Administration initiated

a long-term underground corrosion program. This work has been recently

described in NBSIR 82-2509 entitled Corrosion Evaluation of Underground

Telephone Shielding Materials. Forty-eight systems exposed for periods

ranging from 1 to 6 years at 6 different test sites are described in

detail, and 12 are not recommended for use. Another 13 are indicated as failing when coupled to copper at one or more of the test sites. The

remaining 23 developed varying degrees of corrosion which may warrant

561-18
further study. One of the systems, System 65, which is a polyolefin

polymer coated aluminum alloy shield bonded to the outer jacket performed

well at all sites even after 6 years of exposure. A new updated report

is now being completed.

(5) The corrosion of reinforcement bars in concrete bridge decks caused

by the use of deicing salts has been estimated by the Environmental

Protection Agency (EPA) to cost the economy more than $200 M annually.

Efforts to control this corrosion of steel in chloride contaminated

concrete using new protection techniques being developed by Government

and industry have been hampered by the lack of a nondestructive method

for measuring the corrosion rate of steel in concrete. This measurement

of corrosion would allow an evaluation of the effectiveness of the

various protection systems. During the past year this project, which is

under the sponsorship of the Federal Highway Administration, has extended

previous laboratory measurements to an in-service bridge deck located in

Virginia off the Washington, DC beltway and to a nearby new bridge that

was not yet open to traffic. The in-service bridge was of particular

interest because it was widened 2 years before our measurements were

made. The corrosion rates measured on the older original center section

were similar in magnitude to those measured on the newer sections located

on either side. That is, the steel in the newer concrete was corroding

at essentially the same rate as that in the older concrete. The older

section was over 10 years old while the newer section, as mentioned, was slightly over 2 years old. However, the corrosion rate measurements

were found to be much lower on the new bridge not open to traffic. This

new bridge which was also about 2 years old had not been salted in the

winter. Development of the microprocessor system for making these

corrosion measurements is near completion.

Electrodeposition

Subtask 2 of Task 12113

D. S. Lashmore, H. J. Brown, C. F. Derr, D. M. Francella, C. E. Johnson,

D. R. Kelley, J. B. Lewis, F. Ogburn 1

, S. S. Park, J. R. Smerko, D. Thomas 2

, J. F. Weinroth, J. Yahalom3

1 Consul tant

2 Research Associate, Aluminum Association

3 Guest Worker from Israel Institute Technology, Technion, Haifa, Israel

The processing and SRM activities of the Electrodeposition subtask have

involved the following:

(1) Coatings of nickel chromium alloys have been produced by both dc

and pulsed electrodeposition technology. The composition of the alloy

can be varied from about 0.2 wt. % chromium up to 64 wt. % chromium and

is controlled solely through the deposition parameters (not through

changes in the electrolyte composition). The coatings can be produced

crack-free in layers whose thickness is only limited by the deposition

times. The significance of this result is that the nickel-chromium

alloys should be extremely corrosion-resistant (see fig. 5) and at the same time show good wear properties. The characterization of coating

has yielded the optimal pulsed deposition processing parameters to produce

561-19
smooth crack-free alloys. This project is supported in part by the

American El ectropl aters 1 Society and shows promise of providing a commercial technique to deposit corrosion resistant stainless steel coatings.

A patent application has been filed for this process.

(2) A project on the electrodeposition of glassy alloys based on the

nickel-cobalt-phosphorus-boron family has been underway for three years.

It was found in collaboration with Division 564 that the wear resistance

in the dry sliding ring on block geometry is comparable or superior to

hard chromium. The nickel -phosphorus coatings can be produced by deposition processes that do not present the severe environmental problems

associated with deposition of hard chromium. The current efficiency for

the deposition of these metallic glassy alloys is about 50 percent,

compared with about 11 percent for chromium. It was shown that the

nickel -phosphorus metallic glass alloys not only exhibit two distinct

local structural configurations for a given composition, but also that

the configuration (phase) can be selected electronically through the

pulse timing used in the deposition process. It was also shown that the

structure exhibiting the greater Knight shift exhibits a discontinuous

transformation to the structure with the lower Knight shift. Measurements

have been extended to alloys containing up to 42 wt. % phosphorus. No

other processing technique has yet succeeded in producing such a wide

range of compositions. The practical significance of the work on these

metallic glass coatings is that they have been shown to be extremely

corrosion-resistant in chloride environments and, unlike metallic glass

ribbons, these alloys can be economically applied as coatings to protect

against corrosion and even electroformed into large structures. An

EXAFS study of the nickel -phosphorus system is now underway. We are also investigating the effect of high pressure on the transformation of one glassy phase to another with Dr. Stanley Block of Division 561. It

should be noted that several industries in the private sector have

continued our development work on the nickel-phosphorus systems, including

Bell Laboratories, Lawrence Livermore Laboratory, and the Utilite Chemical

Company.

(3) The industries using or producing coating material particularly the

aerospace industry, require means to calibrate their coating thickness

measurement systems. Work continued in the production of coating thickness SRMs that industry requires for the calibration of coating thickness

gauges. A single SRM is a metal coupon, 3 x 3 cm or 1.5 x 1.5 cm, one side of which has an electrodeposited coating of certified thickness.

Most of these are non-magnetic coatings on steel, but also included are nickel, gold, and tin coatings on various metallic substrates. Some 53

different SRMs are available ranging in thickness from 0.7 pm to 2 mm. (Gold coatings are actually certified in units of mass/area, not length.)

These standards are designed for use with either magnetic type or beta

backscatter type thickness gauges. The SRMs are packed in sets and the

SRM catalog lists some 31 different sets. About 4000 individual coating

thickness standards were produced during FY80 and about 4700 were produced

during FY81. New standards of very thin gold are under development in

response to requests by industry.

(4) In response to a request from the Offices of Standard Reference

Materials and Nondestructive Evaluation, we have developed two new

561-20
microhardness standard reference materials, one of 100 kg/mm2 and another

about 500 kg/mm2. The main problems with the standards now available

from the makers of the microhardness instruments are typically (a) the

lack of uniformity of hardness across the surface, and (b) the lack of a certified hardness. The hardness nonuniformity is a result of inhomogeneties in cooling rate and the resultant composition, inhomogeneity, and

grain size variation. Electrodeposition technology allows almost an atomic control of structure and composition. We have succeeded in

fabricating hardness SRMs of significantly improved hardness uniformity.

These will be made available through the Office of Standard Reference

Materials some time next year. Research in this area is continuing to

extend the range of hardness to over 1000 kg/mm2 so that a complete set

of standards will be available. We have had a number of requests from

industry for Rockwell hardness standards and production feasibility will

be evaluated next year.

(5) To enhance productivity and efficiency, the Division has embarked

on a program to automate the production of standard thickness SRMs. The

automation procedure has been divided into three one year phases. The

first is concerned with the implementation of computer compatible measuring

instruments which is near completion. The second is concerned with the

development of computer software and fabrication of an automatic SRM

translation and measuring instrument, and the third with final refinement

of the computer software to include statistical analysis, label printing,

and inventory control. The x-ray fluorescence instrument used for

measuring the thickness of very thin gold and nickel SRMs has already

been connected to a computer and the other parts of the automation

process are ahead of schedule.

(6) A research project dedicated to improving the accuracy of the x-ray

fluorescence thickness measurements is underway. This project has

yielded a set of greatly improved operating parameters for x-ray fluores- cence thickness testing. Further refinement next year will facilitate

the production of new very thin gold standards which have now been

requested by industry.

(7) As a part of a cooperative program with DOE to investigate coatings

on fuel cell heat exchangers which have to be resistant to very hot

phosphoric acid, the Division is measuring properties of a number of

different types of el ectrodeposi ted coatings including electrodeposited

metallic glass alloys, titanium, and titanium di boride, all on copper

substrates. This project has just started; however, a number of nickel

phosphorus metallic glass coatings have been produced on copper substrates

in geometries suitable for corrosion testing.

(8) Dye penetrant crack SRMs have been in production for two years and

last year more than 100 were made. This SRM is fabricated using electroforming technology and consists of alternative layers of copper and

nickel. There are four layers of copper: the thickest is nominally

2 pm, then next 1 pm, followed by 0.5 pm and 0.2 pm. These copper

layers are then electrochemical ly removed and the space that the copper

occupied constitutes the crack. A research project was undertaken to

improve various unsatisfactory manufacturing techniques and to investigate

several important aspects of the crack geometry that have a bearing on

561-21
dye pick-up and apparent crack width. Among the topics that were examined

were: (a) the extent to which the crack edge was "rounded" by the etching

procedure; (b) the depth to which the crack penetrated into the block;

(c) the polishing technique which was known to "smear" the nickel over the

copper; and (d) various techniques to automate the production process. In

order to eliminate as much as possible the rounding of the crack, an improved etching technique was developed and the polishing procedure was changed to reduce to the maximum extent possible the smearing of the nickel.

The depth of the crack was also measured. This project is quite important

as the Federal Aviation Administration is mandating the use of our dye

penetrant crack blocks for use in the inspection of commercial aviation

(wing spars, landing gears, etc.). This requirement has necessitated a significant increase in commitment of manpower to the production of this

SRM. We anticipate producing from 300 to 500 of these standards next year.

561-22
CURRENT,

microA

Figure la Current

leading

fluctuations observed during the induction period

to the pitting of a Fe-12% Cr alloy.

561-23
AMPLITUDE,

ARBITRARY

UNITS

H. P. FILTERED TIME SERIES. A - 0. 9S0 MA, 15 Tine Logo. P-0. 05

2. 2 ..

TIME, ARBITRARY UNITS

Figure lb Time series of random current fluctuations calculated from a model assuming random-occurring active area on a passive

electrode when they repassivate according to various time

functions.

561-24
STAGE

TL

CRACK

VELOCITY

(m

1

At (s)

Figure 2 Data for load-pulsing experiments used for determining the

velocity of stress-corrosion cracks. These results for

Admiralty Metal in aqueous ammonia indicate that the velocity

is independent of the time interval between pulses, At, over

most of the range studied.

j

561-25
Fe with acrylic

Fe with collodion room temp, oir cure

or polystyrene, room

t (min)

Figure 3 Effect of type of polymeric coating on the el 1 ipsometric

measurements of coated iron immersed in sodium chloride

solution. A = phase change of the elliptically polarized

light. It is usually related to film thickness or surface

roughness.

561-26
INCINERATOR

WALL

.EiAf

COOLING 4^

AIR \

SPECIMENS

F V.V^

t I COOLING

WATER

r^/y.y/y/.-:-://.v,7,v,'P

j

| lift* 1*

n'-

,AW.,///-/6y<v7Vi

SPECIMEN DETAIL

Figure 4 RDF-fired incinerators.

561-27
*lt« (an

•00

Figure 5 Anodic potentiodynamic voltammetry of a Ni 20 Cr pulsed electrodeposited alloy in a 3.5 wt. % NaCl solution. Heavy curve,

-200 mV to +200 mV; light curve, -200 mV to +400 Mv. Both curves show regions where passive protective films are formed

in the Ni-Cr alloy (e.g., the vertical portions of the curves where the current remains relatively constant with an increase

in potential). The lower the value of this passive current,

the more protective is the passive film.

561-28
MATERIALS BIOTRANSFORMATIONS AND CHEMICAL DURABILITY IN SERVICE ENVIRON- MENTS

Task 12114

F. E. Brinckman, J. M. Bellama 1

, W. R. Blair, R. Correa-Becker2

, T. F. Degnan3

, R. W. Faas 4, W. P. Iverson, R. B. Johannesen,

W. F. Manders 1

, G. J. Olson, E. J. Parks, J. S. Thayer4, and C. S. Weiss 5

1 NBS Guest Worker, University of Maryland

2 C00P Student, University of Maryland, Baltimore

3 NBS Research Associate, Mobil Research and Development Corporation

4 National Science Foundation (NSF) Faculty Industrial Research Participation Program, 1982

National Research Council (NRC)/NBS Postdoctoral Research Associate,

1980-1982

The objectives of this task are to provide data, measurement methods,

and mechanistic understanding of chemically and biologically mediated

reactions of materials in their service environments. These processes

affect materials durability, the environmental impact of materials

processing and use, and the properties and functions of materials such

as protective coatings and biocides.

The experimental work of this task focuses on elucidating molecular

level interactions of materials with their environments. Biologically

mediated processes such as microbial corrosion are included because of

the significance of these to materials durability. The nature of the

problems addressed has directed development of measurement methods

toward techniques for detecting, identifying, and measuring individual

chemical species, important as degradation products and transport intermediates, at environmental concentrations down to the ng L-1 level.

The experimental and theoretical competences, developed in this task to

support Division thrusts in materials durability, are broadly applicable

to current problems in areas such as environmental quality and emerging

aspects of biotechnology. Accordingly, the task responds to requests

from NBS Program Offices, other agencies, and the private sector, for

measurement data services in these areas uniquely available within the

Division. The program of the task thus extends to a broad range of

activities as outlined below.

Highlights of major accomplishments for FY82 include:

- Development of measurement methods and preliminary data supporting

a new mechanism of anaerobic biocorrosion of bulk iron;

- Incorporation of complementary molecule-specific methods into Mi 1

Spec development for Navy's major procurement of fleet antifoulant

polymers

- Demonstration of theoretical basis for correlating molecular conformations and shapes with independent measurements by liquid chromatog

raphy and nuclear magnetic resonance spectrometry (NMR);

561-29
- Characterization of a mercury-reducing enzyme imparting toxic

metal-resistance in bacteria crucial to bioleaching technology for

copper mining;

- Demonstration of the concentration of organotin biocide residues in

marine surface water microlayers as a key component in their environmental fate.

Determination of Mechanisms Controlling Biodegradation

Biodegradation processes may be beneficial or detrimental. Anaerobic,

biologically mediated corrosion of metals, for example, is now recognized

as a multi-billion dollar problem in the United States. Microbial

degradation of paints, coatings, building stone, masonry, or concrete

are comparable economically significant problems of materials deterioration. On the other hand, microbial metal ore beneficiation processes

account for about ten percent of U.S. copper ore production and are increasingly applied to extraction of lean ores of uranium and other

strategic metals. Common to these biotransformations is the requirement

for measurement techniques that will allow quantitation of metal transport.

Study of the controlling mechanisms of degradation, including measurements

of rates and key transport metal species involved, can lead to valid

assessments of the relative importance of chemical or biological agents.

This information is crucial to the choice of timely and effective control

or applications strategies.

In FY82 we initiated a new program on anaerobic corrosion of metals,

especially iron, with a long-term project recently funded by Office of

Naval Research (ONR). A major finding of preliminary work is that the

accepted view that anaerobic iron corrosion is caused by sulfate-reducing

bacteria acting directly on the metal surface is probably incorrect.

Our work indicates that these bacteria rapidly corrode bulk iron under

anaerobic conditions by production of highly corrosive metabolic products,

and that proximity of the microorganisms to the metal is unnecessary.

The corrosive metabolic product is volatile, and may incoporate phosphorus

and/or sulfur in its composition, as suggested from element-specific gas

chromatography. Our work for ONR will emphasize isolation of this and

related gaseous metabolites that can adversely react with metal surfaces

remote from the biological source. This work will utilize most of the

trace element speciation techniques described in this report, with new applications expected from gas, liquid, and surface characterization

methods development.

Beneficial applications of microbial metabolisms affecting stability and

transformations of useful materials represents a major output of biotechnology. Many of the measurement methods and resulting data base generated

by this task can bear directly on important issues affecting materials

science and advanced biotechnology. Of immediate concern are the mechanisms, both genetic and metabolic, that determine metal resistance and

fate in microbiological communities. We are actively collaborating with

experts in the related fields to augment detailed studies.

The bacterium Thiobacillus ferrooxidans , for example, plays a major role

in ore leaching by generating strong oxidizing agents (Fe 3+

) and by

direct oxidation of metal sulfides i_n situ , yet it is believed that such

561-30
widespread activity is sharply inhibited by certain trace metals (Hg,

Ag, Mo) occurring in ores. Thus, ppm concentrations of such metals can effectively prevent cost-effective bioleaching of tons of copper in a large leach dump.

We have demonstrated, in collaboration with molecular biologists at

Washington University, St. Louis, that T. ferrooxi dans can overcome

toxic Hg(II) by synthesizing a mercury reductase enzyme that reduces the

metal ion to volatile Hg°, utilizing NADPH as an electron donor. This

is the first demonstration of a mercuric reductase in any autotrophic

bacterium and the first demonstration of a mechanism of toxic metal

resistance in T. ferrooxidans . Other bacteria, chiefly clinical isolates,

produce Hg reductases, but the enzyme from our strain is unique in that

it is synthesized constitutively (at all times even if Hg is absent) and

differs in its molecular structure from related enzymes recovered from

clinical isolates (fig. 1).

Toxic metal processing by T. ferrooxi dans is important to the mining

industry as well as to the biotechnology field. This generates interest

in genetically improving bacteria, including conferring toxic metal

resistance, so that more efficient organisms can be developed, capable

of bioprocessing or bioaccumulating a wider range of metal ores. We

envision as essential future applications of metal speciation to monitor

metal ore bioprocessing and to study mechanisms of toxic metal ore recovery. Already, commercial applications of bacteria in metal recovery

or cleanup of bioaccumulation of silver in photographic waste effluents

are under test by industry. Our successful monitoring of cellular

uptake of organotin biocides using both tin-selective liquid chromatography and epif 1 uorescence microscopy, demonstrates how the task may

provide underlying measurement methods to support aspects of biotechnology

concerned with metals processing.

We interact actively with organizations concerned with reducing avoidable

costs from biodegradation, as well as those seeking substitution biotechnology for energy-conserving recovery of low-grade metals from scarce

supplies. We participated in the formation of the first international

working group of experts on biodeterioration of metals and actively

consult with members of the Materials Technology Institute and National

Association Corrosion Engineers (NACE) who share our concerns and views

on needed future research.

Characterization and Performance of Biocidal Organotin Polymers

In FY82, we continued our joint program with the U.S. Naval Ship Research

and Development Center (USNSRDC)to develop bases for a Mil-Spec to

procure major quantities of tailored organotin polymers (OMPs) for use

as fleet marine anti foul ants. Under most active development by the Navy

are copolymers of methyl methacrylate (MMA) and tri butyl tin methacrylate

(TBTM). Field tests of paints incorporating such OMPs have now passed

the four-year mark without failure, and fleet use of 100,000 to

300,000 pounds/year as polymer is planned for 1986.

We are asked to help provide methods for molecular characterization of

these polymers which can support a Mil -Spec to insure long-term anti fouling

561-31
performance. The Mil-Spec will specify molecular characteristics of the

OMPs, since field tests are impractical for such a long-lived product

and accelerated wear/leaching tests are unreliable while the mechanism

of degradation is unknown.

Here, we must combine molecule-specific measurements differing greatly

in sensitivity and method to acquire needed information. We have concen- trated in two areas which feature the complementary measurement capabilities of tin-specific size exclusion chromatography coupled with graphite

furnace atomic absorption detectors (SEC-GFAA) and high field nuclear

magnetic resonance spectrometry (FT-NMR), described in last year's report.

The first method permits us to quantitatively examine the molecular weight

distribution of bioactive organotin groups attached to the polymer

chain; the second method permits direct evaluation of local molecular

architectures surrounding tin atoms (tacticity) using magnetically

active H-l, C-13, and Sn-119 nuclei in samples of these OMPs. C-13 and

Sn-119 spectra are proving to be the most informative.

NMR signals of tin and carbon are greatly influenced not only by their

local molecular environment, but also by longer range interactions found

in large macromolecular arrays such as OMPs. Such distant effects

include both composition and stereochemistry (tacticity). Figure 2a

shows the proton-decoupled C-13 spectrum of the carbonyl region of

OMP-8, a 2:1 MMA-TBTM copolymer. The higher field region arises from

carboxyl bonded to C, the other signal from carboxyl bonded to Sn. The

fine structure is due to nearest neighbor interactions, and appears to

be consistent with the idea that tacticity is nearly random, but with a slight excess of syndiotactic groupings.

Figure 2b depicts the Sn-119 NMR spectrum of the same sample. A comparison

spectrum (not shown) of TBTM homopolymer shows absorption peaked at

82 to 83 ppm, and this polymer must have all triads of TBTM-TBTM-TBTM

composition. We find virtually no overlap between the Sn spectrum of

the homopolymer and OMP-8. This indicates that all triads in the copolymer

must contain at least one MMA residue. The "blockiness" of the copolymer

is thus proved to be very slight.

The question of molecular weight range optimal for longest effect antifouling properties is also of concern. In Annual Reports over the past

two years, we have discussed advances in tin-specific SEC-GFAA determinations of Sn content versus molecular weight distributions in candidate

Navy OMPs. Representative polymers were shown to contain high (50k Daltons)

and low (monomer) tin species, but an absorbed species suspected of

being charged has now been detected. By injecting trace amounts (relative

to polymer) of weak organic acids at measured intervals following injection of the neutral polymer (fig. 3), the absorbed charged tin-containing

species is thereby eluted.

The results have major implications for organotin impurities formed

during large-scale commercial production required by the Navy program.

We cannot yet state whether the charged species represents a competitive

product from the free- radical initiated polymerization of MMA and TBTM

or whether this is a degradation product related to the marine fate of

the OMP. OMPs stored at -78 °C in tetrahydrof uran for one year tend to

561-32
1

lose part of the tributyltin moiety, possible as a cation, without

apparent degradation of the organic backbone. By examining these latest

materials isolated by preparatory- scale SEC-GFAA with both 013 and

Sn-119 NMR, we hope to better understand both process and storage deterioration of these valuable materials.

Development and Applications of New Speciation Methods

A basic measurement rationale has emerged from this which recognizes and

exploits the ubiquitous presence of trace metals and metalloids in

virtually all natural and man-made materials. In practical terms, this means that if measurement methods can be devised that assure sufficient

selectivity and sensitivity, key elements at certain times, in conjunction

with certain materials during some part of their use cycle, will effectively serve as "flags" or diagnostic species for monitoring purposes.

To achieve acceptable measurement criteria, development of means for

coupling suitable element-specific detectors to sophisticated molecular

separation schemes must be pursued.

Last year's report described development and preliminary applications of

a new ultratrace method employing a tin- specific flame photometric

detector (FPD) automatically coupled to a purge and trap gas chromatograph

(P/T-GC). The group is concluding an evaluation of this technique for

speciation and quantitation of a heavy metal in a clinical SRM being

re-released by the NBS Office of Standard Reference Materials (OSRM) as (new) Freeze-Dried Urine.

In the urine SRMs, volatile sulfur compounds are detected in both S- and

Sn-selective modes; involatile ionic tin compounds require borohydride

reduction for their volatilization as stannanes into the GC system and

are detected only in the Sn mode. Some of the major species identified

include (CH3 ) 2 SnH2 and (CH 3 ) 2 S 2

. A monobutyltin species, C 4 H9 Sn3

, (determined as C 4 H9 SnH 3 ) appears in the same chromatogram. Quantitative

results are summarized in table 1.

Table 1. Concentrations 3of Tin and Sulfur Species in

Previous and New NBS Freeze-Dried Urine SRMs

Species "Old" SRM "New" SRM

(CH

3

)Sn

3+

1.0 ND

b

(CH

3

) 2

Sn

2+

ND 0.46

C

4

H

g

Sn

3+

1.5 0.03

Inorganic Sn(II) or Sn(IV) 28.1 ND

(CH

3

) 2

s 2

ND 2.73

aBy method of additions: in pg/L

^ND = not detected.

561-33

A
There are both qualitative and quantitative differences between the two

SRMs, doubtless reflecting different pooled sources. Detection of a butyl tin species in both materials is a notable finding since there are

no known biological butyl ati on reactions comparable to biomethylation.

These results may indicate human exposure to increased world-wide industrial use of butyl tins, at least in the SRM source population. As a wide spectrum of organotins finds greater use in manufacturing and

biocides, methods and standards for health monitoring and occupational

exposure are needed. The SRM speciation methods now demonstrated can greatly assist in meeting these measurement requirements.

Not only is this work an important use of our methods for the health

field, but it provides OSRM with molecular composition of a new SRM in

terms of selected elements. Increased requests for information on our work from government, industrial, and academic scientists around the

world reflect growing recognition of the importance of, and prospects

for, determining trace metal -containing molecular entities in biological

materials. This work is the first metal speciation study of a clinical

standard, and will greatly assist OSRM in meeting growing needs for

related new biological standards.

Another important measurement development for standards involves our continuing use of high performance liquid chromatography (HPLC) coupled

with graphite furnace atomic absorption spectrophotometric detectors for

element speciation. GFAA depends on thermal processes to remove dissolved

organic material from HPLC solvent, to decompose buffers or analyte, and

to provide the final atomization step. The ultimate sensitivity or response for different species of the same element can thus vary widely

depending on the sample matrix. During the past year, we devised means

to improve sensitivity with automated post-column derivatization for

HPLC-GFAA, so that little or no modification of the established chromatographic separations would be required. Part of our goal was achieved

with a new mixing device that simultaneously receives regulated flows of

HPLC effluent and various dilute transition metal salt "enhancer" solutions

prior to transport into the GFAA detector. Thereby, the active surface

of the GFAA cuvette is continually refreshed with enhancer to yield more reproducible atomizations with sensitivity increases up to 50-fold.

Batch treatments of atomic absorption furnace tubes with many metal

salts are sporadically reported to show such enhancements in GFAA. We

systematically evaluated a large group of metal salts as GFAA "enhancers"

for chromatographic separation procedures required by various on-going

sponsored Group projects. HPLC signal improvements for ion exchange

(aqueous buffered eluants), size exclusion (organic eluants), and solvophobic (water-alcohol eluants) were tested with classes of metal -containing

molecules exhibiting widely different volatility or chemical properties.

Effectiveness of any given salt was highly selective, depending mainly

on the analyte element. For example, we reexamined samples from prior

work for the Navy on speciation of toxic organotins leached by sluicewater

during paint removal in shipyards, and achieved greatest enhancement

with di chromate ion. The effect, as figure 4 shows, is more pronounced

with the volatile tri butyl tin species (16X), while the less volatile

di butyl tin component is much less improved (2X). These results suggest

that the mechanism for "fixing" volatile organometal 1 ic analytes may

561-34
1

chiefly rely on formation of involatile transition metal adducts or compounds during the GFAA thermal cycle, but additional studies are required to understand potentially different enhancement mechanisms

dependent on matrix, selected element, and transition metal. Analogous

improvements for a metalloid, arsenic, in complex syncrude oils were

obtained with another metal, nickel.

For molecular characterization of arsenic in shale oil by size exclusion

chromatography, a huge excess of carbonaceous residue must be charred

before GFAA atomization. At the required temperatures over 1000 °C,

many arsenic compounds or their decomposition products volatilize and

would not be detected. In this case, addition of nickel (II) solutions

to the SEC-HPLC system gave optimum signal enhancement for both small,

volatile molecules such as dimethylarsenic acid and As-containing macro- molecular components of shales. These last results have had great

impact on our concurrent collaborative projects dealing with biogeochemical

formation of toxic organometals in fossil fuels (Lawrence Berkeley

Laboratory) and dearsenation of syncrude shale oils for catalytic upgrading

(Mobil Research and Development Corporation).

The long-term commercialization of conventional fuels and chemical

feedstocks from domestic reserves of coal and oil shale is dependent

upon development of new process technology. We described in last year's

report results of our workshop requested by the Department of Energy to assess speciation methodology needed to support efficient processing.

The presence of arsenic in oil shale is an example of a substantial

processing roadblock to the immediate application of current petroleum

refining technology to alternate fossil fuel sources. Arsenic rapidly

deactivates costly hydrodenitrification catalysts, necessitating development of measurement methods that will provide a basis for evaluating

candidate commercial processes for removal of the element from oils

prior to upgrading. Both the molecular forms and quantities of As must

be monitored since prospective dearsenation processes rely on both

physical and chemical effects which, in turn, are species-dependent.

The reliability and ease of transfer of speciation methodology in this

field to the industrial sector will require new standards. OSRM has

supported our efforts to evaluate NBS SRM 1580 Shale Oil as a suitable

matrix for speciating arsenic. Arsenic concentration in this material

(which has been certified only for selected organic compounds) has been

determined by GFAA to be 2 ± 0.3 ppm. Using SEC-GFAA procedures noted

above, As content of SRM 1580 as a function of molecular weight in the

range from 100 to 20,000 was successfully determined. The arsenic

eluted at retention volumes corresponding to 1500 to 2000 Daltons as depicted in figure 5. In a novel variation of the chromatographic

system, we ran the iron-specific chromatogram simultaneously with the

interesting results shown. From these and similar experiments with a wide variety of source shales and oils, characteristic "fingerprints"

for the dual As-Fe SEC chromatograms were obtained. This evidence,

along with other derivatization experiments, leads to the conclusion

that As carriers in process syncrude oils are chemically tied up with

iron-containing macromolecules and that earlier, simpler views for

removal of As in the form of inorganic ions must be revised.

A

561-35
This difficulty was outlined in a series of papers and talks given

during the past year. Our position is that chemical associations between

arsenic and macromolecular iron compounds in both naturally-occurring

source shale kerogen and the thermally modified retort oils, required a basic study of the underlying chemistry for process monitoring and

control. So far we find that lower molecular weight arsenicals are likely bonded to the iron macrocomplexes. Treatment of shale oil with

silylating reagents disrupt the As-macromolecular bonds to yield small

As-O-Si molecular derivatives speciated by dual As-Si SEC-HPLC. These

and related data suggest anionic forms of inorganic and organoarsenical

s

are dative-bonded to the macromolecules through strong Fe-O-As bonds.

During the past year, Mobil Research and Development Corporation has

arranged through our NBS Research Associate Program to join our Group's

project on speciation of arsenic in shale syncrudes. Our Associate has

verified presence of arsenic acids in shale oil by extraction into

aqueous solutions which by ion exchange HPLC-GFAA permit speciation of

those inorganic and organoarsenic species expected to require removal

for large-scale plant processing. The evaluation of four major industrial

dearsenation processes using these methods is underway or nearly completed.

The underlying ion-exchange chemistry used by the Group originally to

develop the speciation methods and the favored means emerging for oil

dearsenation appear closely related. Ultimately, preferred removal

techniques may be quantitated for various shale sources on the bases of

As MW distributions and associated chemistry. Table 2 provides a summary

of preliminary findings for arsenic concentrations in oils from several

shales as a function of molecular weight.

Table 2. Relative Abundance (in ppb) of Arsenic in Shale

Oils from Various Sources

MW Fraction3 = 1 2 3 4 5 6

Eastern 38 52 24 19 17 44

Western 186 174 58 29 8 6

Silylated Western 61 177 150 116 17 10

Delayed Coker 6 15 21 11 5 5

a

l = > 1600; 2 = 1600-1200; 3 = 1200-800; 4 = 800-400;

5 = 400-200; 6 = < 200.

Installation of an epi f 1 uorescence microscope facility in the Group's

laboratories is completed. Initial studies reveal its applicability to

a wide range of previously inaccessible materials problems, especially

speciation of key metal -contai ni ng molecules for i_n vitro diagnosis of

micromorphological changes on surfaces undergoing both biological and

chemical attack. The biodeterioration of SRMs, especially those based

on naturally-occurring matrices for clinical and environmental users, was rapidly assessed for 0SRM using fluorescent dyes to detect metabolites

from microbial growth in contaminated liquid (urine) and solid (oyster

tissue, orchard leaves). We also applied the technique to directly

assay algal and bacterial deterioration of commercial paint films as

561-36
part of a new project sponsored by the American Paint Research Institute.

Initial results indicate a means for rapidly determining the extent of

biological attack in deteriorated paints, and consequently the efficacy

of biocide formulations in commercial paints.

Many fluorescing agents, including some that selectively fluoresce with

certain metallic ions, are already available, and much future development

for their use is expected during coming years. We recently demonstrated

the use of 3-hydroxyflavone, which selectively fluoresces with certain

organotin ions and Sn(IV), to study the cellular uptake of environmental

tin species by bacteria isolated from the Chesapeake Bay. This work has

attracted the support of the Office of Naval Research which is assisting

us in computerizing our present facility to provide high resolution

graphic mapping of surface interactions involved with bacterial corrosion

of metallic surfaces. We additionally plan, with other members of the

Materials Chemistry Division, to assess the utility of nondestructive

testing of ceramics for trace metal distribution patterns by speciation

with selective coordination ligands. Such rapid, possibly quantitative

optical detection methods can be very cost beneficial for monitoring

iron contamination of technological ceramics which may result in catastropic product failure at high temperatures. The NBS Office of Nondestructive Evaluation is considering a research proposal along these lines

submitted at their request.

Advances in Separation Science Based on Molecular Topology

This report illustrates the procedure for routine determinations on monitoring for the presence of one or several selected elements within a complex matrix at ultratrace (ppb or ng/g) levels; we can sometimes

authenticate their local molecular features by certain independent

measurements. The logical prospect fully of exploiting such useful

indicators of materials behavior by establishing underlying correlations

between molecular architecture and more generally available measurement

methods has therefore become a central scientific thrust embodied in

much of the Group's output.

Modern HPLC techniques reliably separate a huge variety of molecules by

highly selective surface-solution interactions which depend on their

size (molecular weight) , ionicity (charge), polarity, or hydrophobicity

(1 ipophi 1 icity). Commercially available column substrates provide

reproducible, molecularly tailored surfaces and activities that allow

rapid equilibration and separation by any one of the above mechanisms.

For these reasons, and our preliminary success reported last year, in

correlating well-known molecular substituent parameters (QSAR) with

chromatographic retention of organometall ic compounds, we have sought to

extend the basic relationship of molecular shape to chromatography and

other key measurement methods.

Currently, our emphasis is placed on computation of total surface areas

(TSA) of molecules, derived from literature bond distances, bond angles,

and Van der Waal s' radii fitted within conformational or sterochemical

constraints expected for a molecule situated in a polar medium. Recently,

we have been granted access to the PROPHET NET, a very powerful computer

system for generating molecular models interactively in any desired

561-37
configuration. This advanced computing capability will greatly speed

the necessary calculations. Our experimental approach is firmly grounded

in solution thermodynamics, and the shape calculations rely upon experimental data independent of solution measurements.

Table 3 illustrates a very simple but important linear relationship

found between TSA and water solubility for a series of methyl element

molecules, including several well-known to influence global transport of

essential and toxic elements.

Table 3. Correlation of Organoel ement Geometry with Aqueous Solubility

Compound

°2

TSA, A^

Log Solubility3

obsd. calcd.

b

CH

3

Br 73.1 0.81 0.81

CH

3

I 82.1 1.000 1.149

(CH

3

) 2Hg 104.8 1.884 2.018

(ch

3

) 4

c 120.3 3.126 2.61

(CH

3

) 3

Sb 128.1 2.9 2.91

(CH

3

) 4

Sn 153.1 3. 637

c 3.865

a Literature values

b

r=0. 975

c unpublished NBS data.

We find further that calculated TSA accurately predicts HPLC retention

on columns providing solvophobic separations of neutral organometal 1 ic

molecules. Additional correlations with other measurements techniques

are being evaluated: the linear relationship between TSA and NMR is the

most promising because it places a powerful nondestructive spectrometric

technique for molecular characterization at high concentrations into a quantitative relationship with the proven ultratrace HPLC-GFAA technique.

Figure 6 summarizes important new relationships for which linear correlations appear general. For a series of organotins similar to those

previously discussed, the relationship between Sn- 119 FT-NMR chemical

shift and 7i (a biological QSAR established by Hansch) and TSA is compared

with a summary of the other correlations noted. Our present line of

study examines the most favorable molecular conformation in a given

medium and its associated TSA and NMR with respect to "penetration" of

diamagnetic solvent molecules to the central magnetically active nucleus,

here Sn. The combined effect of the surface area and volume requirements

for closest approach between analyte Sn molecule and solvent molecule(s)

possibly controls the overall bulk diamagnetic susceptibility term, and

chemical shift, of the organotin. In addition to this, parallel NMR

561-38
studies evaluating 2

J<- n £

and 3

J<- n £

spin-coupling constants will be useful

in assessing preferred conformations in bulk solution, since these also

seem to correlate with log k and 7t.

Environmental Measurements of Materials Performance and Fate

The International Tin Research Institute estimates that current world

production of all organotins exceeds 3 x 10 7 kg/year. Most of these

applications for organotins result in wide dispersal (as paints, plastics,

wood preservatives, etc.) in the environment. Unfortunately, relatively

little is yet known how these bio-active materials are transported or sequestered in environmental compartments, especially aquatic waters and

sediments. In addition to their major fleet antifoulant requirements,

the Navy is concerned for environmental impacts of their annual multimillion cubic meter dredging operations which involve sediments receiving

increased loadings of organotins as well as other toxic metals. Similar

concerns are recognized abroad as well.

Two task activities over the report period bear directly on these concerns.

At the request of the Naval Civil Engineering Laboratory, we initiated

studies on the nature and rates of organotin leaching from OMP-impregnated

wooden pilings for shore installations. These pilings are prepared by

i n situ polymerization of various organotin-containing precursors directly

within the wood matrix, producing a stable, very slow release anti fouling

preservative. Our project seeks to overcome deficiencies of prior

methods for accurate measurements of organotin release rates from such

treated materials, i.e., the slow release rates were poorly defined

because leachates were at extremely low concentrations and simple total

tin measurements yielded little understanding of release mechanisms of

active toxicants. Our approach employs combinations of HPLC-GFAA and

P/T-GC FPD, described above, to acquire sufficient rate and species data

for estimating long-term (years) field effectiveness. Laboratory simulation experiments are designed to complement field measurements.

In considering the environmental transport and fate of organotin biocides

used in aquatic systems, our current experience, in agreement with other

workers, indicates that very little tin in the form of organotin species

exists in bulk seawater. We demonstrated last year that neutral tetramethyltin and some methystannanes occur in polluted harbor waters, but

most of the organotins are bound to particulates or sediments. In a recently concluded joint study supported by the Dutch Government (International Agricultural Centre) one of our Group members set up complete

speciation facilities in The Netherlands emulating the NBS facilities.

Studies of heavily polluted column waters and sediments in Rotterdam's

Europort made it clear that relatively little of tributyl- or triphenyltinbased anti foul ants in' common use there could be detected. Rather, only

small concentrations of methyltin species, possibly biogenic, were speciated in sediment pore waters by P/T-GC-FPD. In such harbor waters

so heavily laden with petroleum, it is possible that other organotins

present would partition into the oil phase preferentially. We intend to

continue the joint research with the Dutch, but review of our evidence

suggested that we first consider speciation measurements of the aquatic

microlayer as an important sink for organotins as well.

561-39
The aquatic surface microlayer is a thin (50 to 800 pm) film at the

air-water interface in terrestrial and marine environments. It consists

of oleaginous natural and man-made products with natural debris from

biological and geological sources. It provides a large array of micronutrients which support very large microbial populations. Over the years,

scientists have concluded from total element analyses that considerably

amplified concentrations of heavy metals can occur in microlayers in

comparison with underlying waters.

As a result of these considerations and our Rotterdam data, we initiated

field studies to speciate trace organotins in the surface microlayers of

the Chesapeake Bay. Our results to date, though preliminary, are definitive and remarkable. Figure 7 shows that while (CH3 ) 2 S and (CH3 ) 2 S2 concentrations in bulk water exceed those in the microlayer, organotins

can be concentrated in the microlayer ranging from slight to substantial.

Interestingly, chief methyl- and butyltins detected are also those found

in the human urine samples. Thus far, we cannot reconcile the relative

concentrations of methyl- and butyl tin species with expected pollution

sources (more butyltins in busy harbors).

These novel results dramatically illustrate the present inadequacy of

reasonable data bases for modeling fate of important new industrial toxicants.

Since the microlayer is an environment subjected to highest insolation and

aerobic conditions, it further seems reasonable that many nonbiological

transformations of organotins (and other metal compounds) can occur with

possible release of more volatile products into the atmosphere. Investigation of these prospects forms part of our task's long-range objectives.

561-40
MINUTES 30°C

Figure 1 The constitutive mercury-reducing enzyme isolated from T. ferrooxidans is molecularly unlike the Hg-reductase produced

by E. col

. Effects of antiserum prepared against a purified

reductase from a clinical isolate, on mercuric reductase from

T. ferrooxidans (closed symbols) and E. col

(open symbols)

are shown. The E. col

enzyme is totally inactivated by the

antiserum (A), whereas the T. ferrooxidans enzyme is not (A).

Both enzymes are inhibited nonspecifically by the rabbit serum

itself (,).

561-41
13 - C NMR of OMP - 2

(Carbonyl region)

119 - Sn NMR of OMP - 2

Figure 2 Interpretation of carbon and tin molecular environments in

OMP-2 by FT-NMR gives information on polymer tacticity.

A. 013 (H-l) NMR spectrum (with carbonyl region shown) of

OMP-8 in benzene. Spectrometer frequency 50.3 MHz;

1562 scans; 2 level H-l decoupling; total acquisition

time 130 min.

B. Sn- 119 (H-l) NMR spectrum of OMP-8 in benzene. Spectrometer frequency 74.6 MHz; 400 scans; nuclear Overhauser

effect suppressed; total acquisition time 33 min.

561-42
OMP - 2

SEC - G F A A ySTYRAGEL 10

3 A ( ONE )

MW

1 1 1 1 105 10

4 103 10

2

1 1 r

5 10 15 V

R

. mL

Figure 3 Tin-specific SEC-GFAA chromatograms of OMP-2 (a copolymer)

illustrate desorption by injecting acetic acid into THF

mobile phase. Abrupt termination of tailing behavior is due

to reduced retention of absorbed charged species, possibly

tri butyl tin cation.

561-43
CITRATE/H

2

0

10 20 30 MIN

Figure 4 Tin-specific HPLC-GFAA chromatograms are compared for a leachate solution from shipyard grits resulting from spent

anti fouling paint removal. The lower chromatogram shows

GFAA response without co-mixing di chromate solution in the

transfer cup; the top chromatogram illustrates typical

results with additions of Cr enhancer.

561-44
NBS SHALE OIL SRM 1580

0 10 20

ML

30 40

Figure 5 Dual-element SEC-GFAA chromatograms specific for As and Fe are compared for the NBS Shale Oil SRM in tetrahydrofuran.

The maximum absorptivity in the tandem UV trace indicates

the heavy organic loading of the oil. Coelution of As with

Fe at 22 mL suggests common macromolecular carriers with

molecular weights of ca. 2500. Post-column addition of N i (II)

enhanced the As signal and insured equivalent As response

throughout the elution.

561-45
CAPACITY

FACTOR,

Ink

TOTAL SURFACE AREA TSA, X2

300 325 350 375 400 425

Figure 6 Log of column capacity factor, In k

1 , (left) and Sn- 119 NMR

chemical shift, 6, (right) plotted against total surface area,

TSA, (top) for a series of molecules, (n-C^H-^Sn^gH,^

n

- TSA is directly proportional to the sum of Hansch's n parameter

for individual substituents (bottom). Curvature in the

Hansch - In k

1 correlation is thought to derive from lack of

correction for preferred molecular conformations in the simple

additivity rules used.

561-46

CHEMICAL

SHIFT,

d

119

,

PPM
BLANK

MARY S

DELIGHT

BLACK MARSH ^ W

CALIBRATION

O 12 min

Figure 7 P/T-GC FPD detection of organo-tin and -sulfur compounds

from surface microlayer (M) and underlying surface water

(W) are compared for various stations in the Chesapeake

Bay. The blank (top represents a typical water rinse of

the clean teflon sampler sheet (1.6 m2 ). Authentic

compounds in the calibration mixture were: (1) CH3 SnH 3 ; (2) (CH 3 ) 2 SnH2 ; (3) (CH 3 ) 2 S; (4) (CH3 ) 3 SnH; (5) (CH3 ) 4 Sn;

(6) C 4 H 9 SnH 3 ; (7) (CH3 ) 2 S 2 ; (8) (C 4 H 9 ) 2 SnH 2 with samples

treated by borohydride.

561-47

HIGH TEMPERATURE MATERIALS CHEMISTRY FOR PROCESSING AND DURABILITY

Task 12115

The principal task objective is to provide a general high temperature

chemistry measurement science base for advanced/substitute/conventional

materials processing (e.g., ceramics and glass) and service behavior

(e.g. , hot corrosion and slagging). This objective is accomplished

through advancement of experimental methodology, modeling of ceramic/metal

gas-liquid-solid equilibria, and through evaluation-compilation and

dissemination of, Phase Diagrams for Ceramists, books which emphasize

systems containing oxides, sulfides, sulfates, halides, C- and N-containing

compounds, and involve solid, liquid, and gaseous species.

Molecular specific experimental methodologies and theoretical modeling

tools are being developed and applied to the determination of basic

thermochemical and kinetic data and chemical mechanisms for interactions

of metals, ceramics, and glasses with aggressive gaseous high temperature

service environments. These methods primarily emphasize the identification of molecular species, together with accurate measurement and model

predictions of their concentration, spatial, and temporal distribution

in high temperature vapors and gases, and in the presence of complex

solid or liquid phases. The related i_n situ measurement problems of

temperature and flow (gas phase) are also addresssed by this task.

Characterization of condensed phase composition and structure is achieved

by x-ray and neutron diffraction, electron microscopy, and electron

spectroscopy for chemical analysis (ESCA). We have separated the principal task into four subtasks: (1) Chemical Vapor Transport in Reactive

Atmospheres; (2) Phase Diagrams for Ceramists; (3) Characterization of

High Temperature Gaseous Service Environments; and (4) Synthesis, Structure, and Dielectric Properties of Complex Oxides.

The results of this work are required for (a) performance predictions

and test method development in new high technology applications such as coal-combustion and conversion and advanced propulsion systems, and

(b) to support materials processing at high temperatures including chemical vapor deposited coatings, and metallurgical, ceramic, and glass

processing. In addition to base program support, the task addresses

other NBS program and other agency needs, including those of the Office

of Standard Reference Data (OSRD) (phase diagram evaluation/compilation),

DOE-Fossil Energy (alkali vapor transport). Army Research Office (ARO)

(alkali chemistry in flames), NASA (gravity effects on flames, levitation

calorimetry of liquid tungsten), Dupont-DOE Savannah River (vaporization

of nuclear waste glass). An expanded effort in the Phase Diagrams for

Ceramists (PDFC) activity is expected in FY83 with probable new support

from the American Ceramic Society.

Major accomplishments during FY82 include the following:

(1) Volume IV of Phase Diagrams for Ceramists, containing 570 critically

evaluated new diagrams of metal -oxygen, metal -oxide, and oxygen-containing

radical type systems, was published by the American Ceramic Society.

Final editing of Volume V, containing about 750 new diagrams of halide,

sulfide, oxynitride, aqueous, and ceramic-gas systems was substantially

completed.

561-49
(2) A new theory for mixing of complex liquid and solid phases has been

developed and validated (by comparison with experimental activity and

phase equilibria data) for representative ceramic, slag, glass, and

molten salt systems containing K2 0, CaO, A1 2 0 3 , and Si02 ; or PbCl 2 , CsCl , PbBr2 , NaBr, KBr, and CdC

1

2 in the latter case.

(3) Reactions between HCl-containing gases and glass or dolomite substrates, leading to alkali vapor transport have been shown to be highly

rate limited. This indicates that chemical kinetic factors must be

included in current thermodynamic modeling efforts for the prediction of

alkali vapor transport in coal conversion/combustion systems.

(4) The effect of particle size on sintering properties (density and

strength) of potassium and calcium aluminosilicate phases has been

determined, leading to a new synthesis of refractory ceramics with

improved density and strength.

(5) Further refinement of the structural characteristics of lithium

insertion type phases is being carried out in a collaborative study with

J. Cava, Bell Laboratories, using the unique capabilities of the NBS

materials research reactor. These materials have significant potential

in a wide variety of new engineering applications because of their fast

ion conduction properties. For example, Bell Laboratories, has recently

applied for a patent on an innovative high energy battery utilizing the

special characteristics of Li-insertion phases as electrolytes.

(6) The "continuous" phase transition in ZrTi04 , an important microwave

dielectric, was characterized and single crystals containing no superstructure, and both incommensurate and commensurate superstructures were prepared by various techniques. The influence of Sn02 on the unique

characteristics of this phase transition were elucidated.

Chemical Vapor Transport in Reactive Atmospheres

Subtask 1 of Task 12115

J. W. Hastie, D. W. Bonnell , E. R. Plante, A. B. Sessoms, and W. S. Horton 1

1 Consul tant

This subtask develops and applies new or improved measurement techniques

to the molecular-level analysis of vaporization processes for high temperature solids (e.g. , ceramics) and melts (e.g., coal slags, glasses,

and salts) in process atmospheres containing reducing, oxidizing, carbonated, halogenated, sulfated, and hydrous components. These conditions

and the data obtained are generic to high temperature process environments,

and particularly those where hot corrosion and high temperature oxidation

are material s-1 imiting factors. For example, in the developing technology of pressurized fluidized bed combustion (PFBC), removal of coal

and dolomite-derived alkali (Na and K-containing species) impurities to

a gas stream concentration level below 0.02 ppm is necessary to control

hot corrosion of turbine blades in PFBC. Our participation, at DOE's

request, in the DOE-Morgantown Energy Technology Center R&D program on particulate and alkali control in coal combustion process streams,

provides for close interaction and technology transfer with Industrial

561-50
participants, particularly General Electric, Westinghouse , the Electric

Power Research Institute, Exxon, and a number of relatively small air

pollution technology companies. Our expertise in this area has also led

to a very recent request, and a formal collaborative program, by the

DuPont Atomic Energy Division for NBS to carry out vapor transport

measurements over simulated nuclear waste glass materials. These data

are urgently required for the design of process conditions in isolating

nuclear wastes in glass materials.

In cooperative work with DOE sponsors, the recent measurement focus has

been on ceramic, coal slag, and glass systems in atmospheres typical of

coal gasifiers (CG), and pressurized fluidized bed combustors. These

extreme conditions have required continued development of the transpiration (TMS) and modulated molecular beam Knudsen effusion (KMS) mass spectrometric techniques. Complementary efforts in data-base (solution

activities, species Gibbs energies,...) acquisition and computer modeling

have also become an integral part of this extreme-environment characterization effort during the past year. For most of the coal conversion and

combustion systems of interest, the chemical state of Na- and K-containing

species represents a pervasive theme in our understanding of the high

temperature processes and of materials durability problems (e.g., in CG

and PFBC). Examples of recent experimental and modeling activities

pertinent to these problems are summarized below.

Computer Modeling

The large body of vapor pressure and related thermodynamic activity data

obtained in our laboratory in recent years has provided us with a unique

opportunity for data systematization and testing of various predictive

models. During the past year we have developed a highly successful

computer-based model for the prediction of solution activities, vapor

pressures, and (potentially) phase equilibria in ceramic, coal slag,

glass, and molten salt systems. The basis of this model, is the assumption that condensed phase activities, or effective concentrations, are determined primarily by multicomponent equilibria between complex liquid/

solid components. Thus, for example, the activity, or effective concentration, of K2 0 in K2 0-Si02 mixtures is determined by competing equilibria

(solids/liquids) of the type:

«

2

0 + Si0

2 = K

2

Si0

3

Si0

2 + K2

Si0

3 = K2

Si

2

0

3

, etc.

Once equilibrium between these component liquids/solids is established’

the mixture is considered to be ideal with respect to all of the postulated components. This approach contrasts with classical solution

theory where only K2 0 and Si0 2 , for example, would be considered as solution components in a thermodynamic description.

A comparison of model predictions and experimental data for K-pressures

over K2 0-Si02 mixtures is given in figure 1. Note that the two sets of

data in best agreement are represented by our experimental and model re- sults. The model has also been successfully applied to glass systems

and typical results are given in figure 2 for the SRM-621 glass. Note

561-51
the excellent agreement between our Knudsen effusion mass spectrometric

data (Plante curve) and model points. Table 1 indicates the glass

overall composition together with the component liquids and solids

considered in the model calculations.

Table 1. Model Components in SRM-621 Glass.

Wt. % - Na

2

0 (12.71), K

2 0 (2.01), CaO (10.71)

MgO (0.27), Si0

2 (74.3), Al^ (2.77)

Significant components (liquid) at 1400 K

a

Na.

? Si0j- K2

Si 4°9 Si0

2

, CaSi0

3

Na,,Si0

3

K

2

Si

2

0

5 Ca0-Mg0-2Si0

2

K

2

S10

3

(Al

2

0

3

-Ca0-4Si0

2

)

Insignificant (liquid + sol id)

b

Al

2°3

3Al

2

0

3

-2Si0

2

K

2

0 K

2

0-9A1

2

0

3

Na

2

0 Ca0-Al

2

0

3

CaO 2Ca0-Mg0-2Si0

2 MgO Al

2 03

*Ca0*2Si0

2

kaio

2

Al

2

0

3

-2Ca0-Si0

2 KAlSiO.

4

KAlSi

2

0

6

12Ca0*7Al

2

0

3

Significant components are those having > 10 -4

mole fraction concentration as predicted by

the computer model.

insignificant components are those considered

but calculated to be present at < 10-4 mole

fraction.

Based on initial external responses to our model we expect broad future

usage by industrial and other research and development communities. In

recent months the following establishments have expressed an interest in

utilizing our computer progam, data base, and related material: D0EMorgantown (slag modeling); DuPont-Wi lmington (glass-metal wetting);

A. Cooper-Case Western Reserve (diffusion in glass); DuPont-Savannah

River (nuclear waste processing); PPG-Pittsburgh (fluoride glass volatility in fiber production); CSIRO-Sydney (fluidized bed coal -slagging)

;

561-52
New South Wales Electricity Comm. -Austral ia (steam plant design for high

slagging coals); and St. Gobain-France (glass processing). Also,

Or. N. Christensen of F. L. Smith and Company (Denmark) has recently

pointed out to us the potential importance of this modeling activity to

alkali vapor transport in cement processing.

In principle the model should also permit calculation of phase diagrams

and we will pursue this aspect in future work. We should stress, however, that the viability and reliability of this model require continued

testing as additional components are added to the database. Thus this

closely coupled experimental and modeling effort will be continued in

FY83 for optimum development and public dissemination of this model.

Alkali Vapor Transport Over Complex Oxide, Slag, and Glass Systems

Dolomitic limestone is used for sulfur retention in fluidized bed com- bustors. However alkali impurities in the limestone, together with the

neutralizing effect of this basic material on alkali-containing coal

mineral impurities (e.g., illite), can lead to excessive alkali vapor

transport and corrosion of downstream components. To determine whether

alkali vaporization from dolomite itself will exceed the tolerance (to

hot corrosion) limits for turbine gas streams we have obtained vapor

pressure data, as shown in figure 3. The good agreement between the TMS

and KMS data is noteworthy. The several order of magnitude difference

in characteristic residence times for these two techniques suggests that

the system readily achieves thermodynamic equilibrium. Note that at the

1200 K temperature expected of PFBC operation the alkali pressure is

above the turbine tolerance limit of 0.02 ppm.

Alkali absorbant materials such as glass, slag, bauxite, etc., are under

study by various industrial laboratories (G.E., Westinghouse) associated

with PFBC development. High alkali vapor pressures over these materials

may limit their efficiency as absorbants. Also, alkali sensors are under development for monitoring combustion gas streams and reference

vapor pressure data are desirable at the temperatures and partial pressures

of usage. In response to these needs for accurate alkali partial pressure

data over glass systems, we have obtained data over the SRM-621 glass as shown in figure 2. These data were obtained by the KMS method after vacuum outgassing. The complementary TMS experiments showed anomalously

high Na pressures due to the presence of unreacted carbonate impurity.

Thus, this SRM-621 glass is not suitable for vapor pressure studies

without prior purification.

Alkali Vapor Transport in HC1 Atmospheres

Under service conditions, atmospheric components such as H2 0, HC1 , and

02 can be expected to significantly modify alkali vapor transport through

mass action effects or the formation of new molecular species. In coa'

conversion and combustion processes HC1 is an important gaseous impurity,

particularly in its anticipated reactivity with alkalis to yield volatile

species such as NaCl , KC1 , and CaCl 2. New experimental work has been

initiated on heterogeneous systems containing glass and dolomite togetne--

with HC1 gas using the TMS and KMS techniques. Sufficient data have now been obtained to reveal a number of potentially important novel aspects

561-53
of these heterogeneous processes. First, even though the high temperatures involved (1000 to 2000 K) and the relatively long gas residence

time (up to 20 s) would normally ensure attainment of thermodynamic

equilibrium, instances of nonequilibrium behavior were found.

Typical data for the SRM-621 glass, HC1 system are shown in figure 4.

Note that the production of NaCl is many orders of magnitude less than

the equilibrium value. In spite of this lack of equilibrium, transport

of alkali as NaCl is much more important than vaporization as Na. At

relatively low HC1 pressures, the deviation of K

p

from the steady state

value is most likely due to an error in the HC1 pressure measurement

because of scattering of residual HC1 into the ion source. At relatively

high HC1 pressures (> 10"6 atm) a steady state is no longer achieved.

Presumably, at high vaporization-rate conditions, the rate of diffusion

of Na through the glass becomes rate limiting.

Analogous studies were made for the dolomite SRM 88a-HCl system using

the KMS and TMS techniques. At relatively low temperatures of 400 to

800 °C, using the TMS technique, large amounts of HC1 were consumed with

a concomitant production of H 2 0. Also, similar KMS experiments showed

CaCl 2 (g) at pressures close to those for unit activity CaCl 2 (s). These

observations are indicative of the initial process

2HC1 + Ca0(s) = CaCl

2

(s) + H

2

0.

Alkali vapor transport from dolomite in the presence of HC1 gas can be

expressed by the processes:

K

2

0 (in dolomite) + CaCl

2

(s) = 2KCl(g) + Ca0(s) (1)

K

2

0 (in dolomite) + 2HCl(g) = 2KCl(g) + H

20(g) (2)

Since the activity of K2 0 in dolomite is known from our mass spectrometric

measurements in the absence of HC1 , and the Gibbs energies of formation

are known for all the reaction components, the thermodynamic equilibrium

constants can be computed for reactions (1) and (2). The apparent equilibrium constants (KMS experiments) determined from the observed pressures

of KC1 , H 2 0, and HC1 are about a factor of 10 14 less than the true equilibrium values. It is somewhat surprising that both of these reactions

showed a similar large degree of departure from equilibrium. We had

expected reaction (1) to be more favorable based on our previous experience with solid-solid alkali exchange processes. Analogous TMS experiments

indicated only a factor of 108 departure from the equilibrium values for

both KC1 and NaCl vapor transport. The higher efficiency of TMS as com- pared with KMS experiments can be attributed to the longer gas residence

times and higher HC1 pressures used with the TMS method. As was the case with the glass-HCl system, even though the reaction to produce alkali

halide is kinetically hindered, a significant enhancement in alkali vapor

transport results from the presence of HC1 gas. Further work on the

extent and reaction rates of these gas--solid (or liquid) reactions will

be carried out in FY83.

561-54
Phase Diagrams for Ceramists

Subtask 2 of Task 12115

L. P. Cook, R. S. Roth, T. Negas, M. A. Clevinger, D. McKenna, and

L. Frankenburger

This subtask responds to an established NBS role in the critical evaluation, compilation, and dissemination of phase diagrams for use by

ceramists. As a joint NBS-ACerS activity (with some OSRDS support) the

work is closely coupled with current needs as perceived by NBS and the

ACerS advisory committee. R. S. Roth, T. Negas, and L. P. Cook currently

serve as General Editors of the volume, and commentaries are prepared by

31 individuals, representing an international team of contributing

editors. The NBS editors are responsible for the accuracy of the final

product evaluated diagrams and this requires expert working knowledge of

the experimental and, to an increasing extent, theoretical aspects of

phase diagram construction.

Efforts are in progress to provide computer control over the bibliography

and for phase diagram manipulation and editing. In the past year the

book manuscript text has been converted to magnetic storage and transmitted

in this format to the ACerS publisher, thereby eliminating type setting

errors and additional proofreading. Efforts to computerize the construction of phase diagrams have also been implemented during the past year.

Similarly a significant effort has gone into developing theoretical

approaches to the a priori calculation of phase diagrams for ceramic

systems, e.g., see Subtask 1.

A major accomplishment during FY82 was the publication of Volume IV,

Phase Diagrams for Ceramists, by the American Ceramic Society. This

latest volume of the series contains 590 new phase diagrams with commen- taries describing experimental methods, accuracy and precision of data,

and comparison with other work. Phase diagrams of metal -oxygen and

metal -oxide systems and systems with oxygen-containing radicals are included in this volume. Volume V in the series, scheduled for publication in FY83, will contain 750 new diagrams of halides, halides with

other substances (especially metals and oxides), sulfides, oxycarbides

and oxynitrides, aqueous systems, systems with C0 2 , and ceramic-gas

(primarily C-O-H) systems. Final editing of Volume V will be completed

in FY82 and the manuscript will be submitted to the American Ceramic

Society for publication.

Preparation of Volumes VI and VII in the series also continued during

FY82. Approximately 500 additional references for evaluation were mailed off to contributing editors, and many commentaries have already

been received. These volumes are scheduled for publication by 1985.

It has been long recognized that the use of computerized methods is

essential for operation of the Phase Diagrams for Ceramists Data Center.

During FY82 a proposal was submitted to the American Ceramic Society--

the theme was extensive use of computerized data base management methods

with concomitantly increased support to contributing editors. This

proposal was enthusiastically received by the Society, and was passed by

its Executive Committee. Two committees were then appointed: (1) an Ad

Hoc Advisory Committee on Phase Equilibria Data Center, chaired by

561-55
L. P. Cook, which was given its official mission by incoming Society

president R. J. Beals at the American Ceramic Society Annual Meeting in

Cincinnati, in May; (2) a Fund Raising Committee chaired by former

president J. I. Mueller, with S. J. Schneider of NBS as one of its

members. The former Committee, as well, consists of a number of respected

people in the ceramic science community: T. B. Lindemer, Oak Ridge

National Laboratory; K. E. Spear, Penn State; A. Muan, Penn State;

D. E. Day, Univ. Missouri; E. Ruh, Carnegie-Mel Ion; A. M. Alper, GTE;

B. H. Baker, ARMCO; J. J. Brown, Virginia Tech.; P. K. Gallagher, Bell;

N. N. Ault, Norton; A. H. Heuer, Case Western Reserve; B. Schwartz, IBM;

R. A. Eppler, PEMCO; and G. H. Beall, Corning. The first meeting of

this Committee was held in May. One of the outcomes was a consensus

that the Data Center should expand coverage of nitride and oxynitride

ceramics. To discuss further this and other future directions, in

particular the use of computerized methods in phase diagram manipulation,

a second meeting will probably be scheduled in the near future. It is

anticipated that the work of this Committee ultimately will be of use to

the Fund Raising Committee.

In-house efforts aimed at initial implementation of some of the actions

mentioned in the comprehensive proposal discussed above, pending American

Ceramic Society action, were begun during the fiscal year, largely

through the auspices of the Office of Standard Reference Data. Assistance

to the Data Center has been of two forms: (1) programming assistance,

and (2) a very recent grant of DOE funds. A professional programmer

(C. Messina! has made progress ir developing software for development

and management of the computerized bibliographic file which is essential

for operations such as indexing, searching, sorting, and updating. It

is expected that entry of bibliographic information using this system

can begin in the near future. A current concern is the prospect of

extensive use of computer graphics for phase diagram manipulation.

Because of the volume of materials to be handled it is desirable to

determine the most efficient and yet accurate method of storage and

recall of prase diagram information. A feasibility study of this is

Deing undertaken by in-house personnel (primarily P. K. Schenck). Ultimately a modeling input will be required for the production of phase

diagrams and efforts to gain familiarity with available software are continuing. To this end L. P. Cook attended a seminar on the FACT

system for calculation of phase equilibria at McGill University in May,

and it is anticipated that substantial use of this system will be made

in the near future. Contacts with other researchers doing calculations

of phase equilibria at t^e recent CALPHAD meeting at Argonne in May have

also proved useful, especially interactions with L. Lukas, B. Sundmann,

R. Howald, P. Spencer, and A. Pelton.

C~a-act6"': zat~ c" c~ -~c- ~e-:e r st.-e Gaseous Service Environments

Subtask 3 of Task 12115

P. K. Schenck and J. W. Hastie

Objectives of this Suctass are to develop anc optimize measurement

tecnniques for characterizing high temperature gaseous environments,

including flames, anc to apply the metnodology to assessing and predicting the performance of materials in those environments. During

561-56
1

FY82, further refinements have been made to several new combustion

diagnostic techniques for further application to mechanistic studies of

combustion modification, including flame and smoke retardance. These

techniques rely on laser excitation of electronic states in atoms and

molecules. We have also utilized the enhanced thermal ionization of

laser excited atoms (the optogalvanic effect or laser enhanced ionization) to modify the neutral /ion ratio from which species flow velocity

and diffusion parameters can be determined.

In collaboration with the Center for Analytical Chemistry, modeling and

experimental studies have continued on the collection mechanism of ions

and electrons from laser enhanced ionization (LEI). Maximum sensitivity

is obtained when a water cooled probe is inserted in the flame to co^ect

the signal produced by electrons and ions formed by LEI using pulsed

lasers. Near unity collection efficiency is possible if the laser beam

producing the electrons and ions is within the sheath formed by the

background flame ions around the probe (held at a negative potential

with respect to the burner body). The reason for this has been verified

in computer modeling of the motion of the LEI formed ions and electrons

in the flame. The cathode sheath is the region of highest electric

field and the electrons and ions move fastest in this region. The

computer modeling consists of an animation which demonstrates that the

electrons are rapidly repelled to the edge of the sheath due to their

high mobility compared to the ions. This results in a current in the

flame and an induced charge on the anode (burner). On a time scale

about 200x slower the ions move toward the cathode where they are collected contributing to the signal. Further modeling and experiments are planned to study the possibility of charge transfer to species with

higher mobility to enhance the ion component of the signal as well as the role of ambipolar diffusion in the case of CW laser LEI.

Also in collaboration with the Center for Analytical Chemistry, work

continues on the study of the neutral atom depletion by LEI and its

application as a combustion probe. It is possible via LEI to locally

ionize more than half of the neutral metal atoms (typically Na) in the

flame. This local depletion persists because the ternary recombination

process is slow. A second laser beam is used to map out the motion of

the local neutral atom depletion in time and space. A flame velocinetewith spatial resolution of 1 mm and velocity accuracy better than 3 percent was demonstrated for laminar flow flames. Current work on this

probe is directed at refining the measurement of diffusion coefficients

of neutral atoms in flames.

A krypton ion pumped near-IR dye laser has been installed for studies of

K in flames. Similar concentration mapping with and without LEI "holes

should be possible in normal as well as inhibited K seeded flames. This

work will be done in support of Army and NASA contracts on Secondary

Flash Suppresion and Gravity Effects in Flames respectively. The IR dye

laser will allow us to monitor K concentration either by absorption or

LEI (to the ppb level). Temperature measurements will be made by compute

controlled Raman spectral experiments. The effect of temperature or the

Raman spectra is shown in figure 5. These Raman spectra were calculated

on our laboratory automation computer which will control the monoch •’omato

and data acquisition for automatic temperature profiling of normal aid

561-57
inhibited flames. During FY83 we plan to couple these laser-based flame

diagnostic techniques with the high pressure sampling mass spectrometric

apparatus for simultaneous measurements of temperature and species

concentrations.

Figure 5 also demonstrates the current capability of our automation

equipment for generating camera-ready figures for publication. During

the last year the Hershey character set used on the NBS Central Computer

was transferred via the NBS Net to our local laboratory automation

computer. A demonstration program using these characters has been given

to over 20 users including NASA, COMSAT, NOAA, and the Coast Guard.

Plans are currently underway to issue a flexible disc with the user defined characters in conjunction with an NBS Report through the Office

of Standard Reference Materials. This would make the data file available

to over 50 thousand HP digital plotters at a modest cost. The implementa

tion of the high quality computer calligraphy should also speed up the

automation of the preparation and editing of Phase Diagrams for Ceramists

under Subtask 6.

Synthesis, Structure, and Dielectric Properties of Complex Oxides

Subtask 4 of Task 12115

R. S. Roth, L. P. Cook, J. L. Waring, A. E. McHale, H. S. Parker 1

, R. J. Cava 2

, and L. P. Domingues 3

Research Associate, American Ceramic Society

2 Guest Worker from Bell Telephone Laboratories

3 Guest Worker from Trans-Tech, Inc.

This subtask addresses structure-property relationships for oxides

important as refractory or electronic ceramic materials. It also couples

closely with the nonexperimental subtask on Phase Diagrams for Ceramists

and provides phase equilibria data on key systems not covered satisfactorily in the Phase Diagram compilations.

Sintering in the K^O-Al^O.d-SiQ? System

Potassium al umi nuosi 1 icate and related materials appeared to offer

particular promise, from a chemical standpoint, as refractories resistant

to high temperature alkali corrosion. We have investigated the role of

sintering in preparation of these ceramics with improved density and

strength. Sintering phenomena are closely related to and governed by

classical phase equilibria, with the added complexity of localized

interfacial phase equilibria in which surface energies play an important

role.

Although potassium aluminosilicates sinter, they do not density appreciably during thermal sintering, if micron-sized powders are employed.

Classical sintering theory predicts that either volume diffusion or grain boundary diffusion must be increased if densifi cation is to be

achieved. Volume diffusion can be increased through the use of reactive

sintering if appropriate reaction paths are available. The only satisfac

tory route found to date has involved use of KAlSi 3 0 8 glass and KA102 to

produce KAlSi 2 0 6( KA1 S i

0

4 produced by this method is not dense). The

561-58
apparent reason for relative success of this method is the high viscosity

of the KAlSi 3 08 glass, which does not crystallize, but acts as a solid

with relatively mobile atoms until reaction is complete at the sintering

temperature. The main problems to date have been the presence of large

residual pores and the presence of a small amount of residual glass.

Also, the method does not appear to work for any potassium aluminosilicates other than KAlSi 2 0 6

.

Another solution involves, instead of a reactive sintering route, the

use of very fine-grained powders, a method which has been demonstrated

in the case of mullite and several oxide ceramics. Initial results

showed a pronounced densification when submicron size powders were used

(see fig. 6). This effect seemed to be related to a grain-size threshold,

and so systematic studies were undertaken to determine if the effect of

alumina contamination introduced during milling and the effect of the

reduction in size could be separated. This was done by milling for

progressive periods of time and weighing milling media so that the

degree of contamination was known. Since alumina is stable with potassium

aluminosilicates up to temperatures well in excess of the sintering

temperatures employed (1300 °C), a marked effect of the contamination

upon the sintering properties would not be expected. Initial experiments

in which commercial fine-grained alumina and alumina from the milling

media were sintered, showed that the latter densified less than any of

the commercial varieties, and less than the milled aluminosilicates,

leading to the conclusion that there is nothing different about the

sintering properties of the mill contaminant that would explain the

enhanced densification of the milled aluminosilicates. The effort was

then made to see if a well-defined particle size effect could be isolated.

This was investigated by quantitative particle size analysis of milled

powders using an SEM image analysis system. By this method a frequency

distribution pattern for the alumina contaminant was obtained which was subtracted from the distribution for the milled powders, thus giving a close approximation to the frequency distribution of the pure milled

aluminosilicate patterns. The differences between unmilled, manually

ground (nondensifiable) , and milled (densifiable) powders are extremely

subtle, consisting mainly of the presence of an expanded tail at the coarse end (> 1 pm) of the frequency distribution plot in the case of

the unmilled material. While the coarse particles may be vol umetrical ly

important if present in more than a few percent, it seems difficult to

ascribe the pronounced differences in sintering behavior to differences

of this kind. Possibly there are differences at the very fine end of

the spectrum not detected with the scanning electron microscope (SEM).

Alternatively the densification may be the result of enhanced volume

diffusion stemming from defects introduced during milling. There appears

to be no x-ray evidence for degradation to the point of structural

breakdown however. From a practical standpoint, it is perhaps most

significant that potassium aluminosilicate ceramics prepared from finely

milled powders, although contaminated with alumina, have strengths

nearly three times those prepared by reactive sintering (~ 100 MPa vs 40 MPa). On another level, if an important role for mechanically introduced defects in these materials can be established, this would have

implications for processing of many other materials as well. It is

possible that examination of vapor pressures of the milled material

would shed some light on the problem.
Sintering in the CaQ-Al?Oa-SiO? System

In contrast to the potassium aluminosilicates discussed above, crystalline

anorthite (CaAl 2 Si 2 08 ) both sinters and densities readily, regardless of

the size of powders employed. This at first seems somewhat puzzling as CaAl 2 Si 2 0 8 , KA1 Si 2 0 6 , and KAlSi04 all have similar structures, i.e., all are tectosi 1 icates. Therefore studies were undertaken in an attempt to

elucidate further the rather remarkable tendency for "self-densification"

exhibited by unmilled stoichiometric anorthite powders.

Pellets of three anorthite powders differing slightly in their preparation (see table 2) were sintered for varying times at 1400 °C. Although

differences in average particle sizes were minimal, the effects on sintering kinetics were quite apparent as shown in figure 7. In particular, batch AN-2, with the finest particle size shows the most rapid

densification, as might be expected. However, a well defined change in

kinetics occurs. A two-stage densification mechanism is proposed for

anorthite to explain this break. During Stage 1, grain boundary diffusion is the dominant densification mechanism, aided perhaps by an intergranular phase. Stage 1 continues until all high energy grain

boundary orientations have been eliminated, a process aided by the

presence of fine particles. Batch AN-1 never reaches this stage of

orientational equilibrium, and hence no break in slope occurs. Stage 2

is thought to result from lattice diffusion, perhaps along closely

spaced parallel twin planes. Surprisingly, all three end products have

similar densities (see table 3, below).

Table 2. Preparationi of Anorthite Powders 1Powder

Powder

Batch

Starting

Materials

Fi rst

HomogenizationCalcination

Second

Homogenization

Est.Avg.

Particle

Size

AN-1 Brazilian Quartz

+ AR Grade CaC0~

+

6

0.3 pm A1 umi na

Ball -Mi lied

1/2 h

1300 °C

12 h

Ball -Mi lied

1/2 h

2 pm

AN-2 Brazilian Quartz

+ AR Grade CaC0~

+

*

0. 3 pm A1 umi na

Mechanically

Mixed

1300 °C

12 h

Ball -Mi lied

1 h

1 pm

AN-3 1. 5 pm Quartz

(0.01 wt. % Fe) + AR Grade CaCO-

+

6

0.3 pm Alumina

Mechanical ly

Mixed

1300 °C

12 h

Ball -Mi lied

1/2 h

3 pm

561-60
Table 3. Densities of Sintered Anorthite Powders 9

Powder Si nteri ng Conditions Density, % Theoretical

AN-1 1400 °C, 1000 h 92

AN-2 1400 °C, 1000 h 96

AN-3 1400 °C

1000 h 94

aMeasured by adjusting liquid density to the point where the ceramic

particle was indefinitely suspended.

The high propensity for pore elimination during sintering shown by anor- thite is a desirable, but frequently unattainable, property for ceramic

precursor powders. Thus further study of anorthite to elucidate the

microscopical reasons for this behavior might prove beneficial in the

development of other readily densifiable materials.

Ceramic Dielectric Materials

Two of the most potentially economically important problems concerning

the electronic ceramics industry are the development of new and/or

better compositions for electrolytes for high energy batteries and low

dielectric loss/high dielectric constant zero TCK dielectrics for a variety of capacitor applications. These two problems are currently

being addressed in this subtask. For ionic conductors current activities

are centered around the use of Li + ions in both equilibrium and non- equilibrium oxide phases. The unique qualities provided by the availability of the NBS Reactor dictate that we can make a strong contribution

in this area of research as the Li + ions can be located by neutron

diffraction but not by x-ray diffraction. Diffraction studies are being

conducted in collaboration with Dr. A. Santoro of the NBS Reactor Radiation

Division and with an international group of crystal lographers (see below).

Properties of many of these materials are being evaluated in collaboration

with Dr. R. J. Cava. Several different titanate systems are currently

being evaluated for their use as zero TCK capacitors. These are either

related to Ba0-Ti02 systems or to Zr02 -Ti02 systems. Phase equilibria

and crystal chemistry of new phases in complex systems containing these

titanates are currently being studied. The properties of various ceramics

dictated by these studies are being evaluated in collaboration with

L. P. Domingues.

A careful study of the data accumulated during the previous year on com- positions synthesized in the system Ba0-Al 2 0 3 -Ti02 indicated that previously

published phase equilibria and phase compatibility studies were probably

incorrect. An attempt was made to determine the phase equilibria in the

nonbinary join Ti02 -BaAl 2 0 4 , containing the nonstoichiometric phase

Ba Al 0 Ti 0 0 with the hollandite structure. It was found that at a

x ^.x o zx lb

composition corresponding to an approximate ratio of BaO: A1 2 0 3

: Ti02 = 2:2:5

the specimen not only contained no hollandite but also contained no BaAl 2 0 4

. In fact it contained no phase previously reported to occur in

this ternary system. Further experiments proved that two new phases,

previously unreported, exist in the system. One of the phases was found

561-61
to be C-centered monoclinic with approximate composition 2:3:4, 2BaO:

3A1 2 0 3: 4Ti0 2 , Ba2 Al 6 Ti 4 0 19 . However, this composition is not known with

any great accuracy due to the great difficulty of obtaining single phase

specimens which, in turn, is due to the extreme kinetic problems involved

in obtaining equilibrium, at temperatures below 1275 °C and the formation

of metastable phases. The other compound was also found to be monoclinic

C2/m, C2, or Cm with a compositional formula of 4BaO: A1 2 0 3

: 1 OT i

0

2 , Ba2 Al 2 Ti lo 0 27 . A specimen of this composition was prepared and found to

be single phase. In view of the occurrence of the two previously unrec- ognized phases the phase equilibrium diagram of this system has been

reevaluated and the revised version is shown in figure 8.

A new program to investigate the physical and dielectric properties of

ZrTi04 and ZrTi04 -based solid solutions has been initiated. The re- search is stimulated by current technological interest in ZrTi04 -based

ceramics as dielectric resonator materials in microwave devices. The

practical application of these materials is presently hindered by incomplete information on the chemistry and structure of ZrTi04 and of

ZrTi04 -based solid solutions.

A study to determine the temperature of the high-low transition in ZrTi04 has been completed, together with a preliminary study on the effect of

substitutional tin on the phase transition behavior. Zirconium titanate

has been shown to have a unique and previously unreported phase transition

most clearly shown in the dependence of the c-axis length of the orthorhombic (Pcnb) unit cell on temperature as seen in figure 9. The unit

cell volume decreases linearly with decreasing temperature between ^ 1480

and the "true" phase transition at 1125 ± 20 °C, apparently continuing to

decrease at lower temperature. The maximum unit cell dimensions are a = 4.806, b = 5.035, and c = 5.498A and are found only at T > 1480 °C. The

minimum unit cell dimensions, achieved only by very slow cooling and

equilibration at ~ 750 °C were found to be a = 4.828, b = 5.035, and

c = 5.348A.

The unit cell dimensions observed for ZrTi0 4 :Sn02 solid solutions did not

exhibit strong temperature dependence, Sn0 2 in solid solution apparently

being effective in stabilizing the random nature of the high temperature

ZrTi04 structure type.

Flux grown single crystals of ZrTi04 have been prepared at temperatures

both above and below the phase transition. The structure of these crystals

is presently under investigation. Initial studies indicate the presence

of a-axis superstructure in the low temperature phase which is not present

in crystals quenched from above the phase transition temperature. The

relationship of this observed superstructure to extra lines observed in

x-ray powder patterns of low temperature ZrTi04 is not clear. Neutron

diffraction studies both high and low temperature forms of ZrTi04 have

been initiated with the cooperation of Dr. A. Santoro of the NBS Reactor

Radiation Division which are expected to yield better information on the

details of anion packing in the structure as relating to the observed

"extra" spots and lines seen in x-ray diffraction patterns.

This work has indicated a need for characterization of the dielectric

properties of the "true" high and low temperature phases of ZrTi04

.

561-62
Studies are proceeding on methods for the low temperature synthesis of

high quality ceramic powders suitable for sintering at temperatures to

produce either high or low temperature structure type. The cooperation

of L. P. Domingues has been obtained for the dielectric characterization

of these specimens as they are prepared. Similarly prepared ZrTi04 -based

solid solutions will be systematically examined to determine the effects

of substitutional cations on the physical and dielectric properties of

technological importance for application in dielectric resonator devices.

Interest in Li 2 0 containing phases has been greatly stimulated by the

possibilities of Li+ ion conduction in such phases for use as a solid

electrolyte in lightweight, high energy battery systems. The phase

equilibria and crystal chemistry of systems combining Li 2 0 and tetravalent and/or pentavalent metal oxides is largely unknown. Studies on the crystallographic properties of Li 2 Sn0 3 and l_i 2 Zr0 3 have been com- pleted during FY82. In addition, our study of the high temperature

form of LiTa3 08 has been completed. Single crystals of LiTa3 08 prepared

by W. S. Brower (deceased) were examined in Grenoble to determine the

true unit cell dimensions and symmetry. A Weissenburg film camera was used on the Grenoble neutron diffraction equipment to give a picture

that revealed extra rows of diffraction spots indicating a superstructure with a doubled 1 b

1 axis (3.8A x 2). This superstructure is not

visible at all by x-ray diffraction even with very long exposure time

although there is some indication of the doubled cell in electron diffraction patterns. A structure refinement of the single crystal neutron

diffraction data has revealed that the Li + ions are ordered in two

different sets of coordination polyhedra in each of the units of the

doubled cell. Rietfield refinement of the powder data does not clearly

lead to unambiguous ordering parameters. In this case single crystal

neutron diffraction is the only technique which has unambiguously led to

the correct determination of the position of the Li + ions in an oxide

structure. Data should be collected and refined from single crystal

neutron diffraction equipment operating at high temperatures to determine

the exact mechanisms. These experiments are under consideration at the

present time at both NBS and at Grenoble.

Further studies have continued on the synthesis, conductivity, and structure refinement of various Li'1'- intercalated (or Li +- inserted) transition

metal oxide phases in collaboration with Dr. R. J. Cava. Considerable

progress has been made in the characterization of Li+- insertion phases

related to the Wadsley-Roth block structures originally reported in Nb-0,

Nb-Ti-0, Nb-W-0, and W-V-0 systems.

561-63
Figure 1 Potassium pressure dependence on total K2 0 mole fraction for

the binary K2 0-Si02 system. Curve Ej is the experimental

curve of Plante (1979) and curve E 2 is the corresponding lower

limit based on temperature, pressure, and composition uncertainties. Curve C is that of Charles (1967) based on a combination

of Preston and Turner's (1933) transpiration data and phase

diagram analysis. The curve labeled EL and the closed circle

are based on experimental and estimated data of Eliezer et al.

(1978) and the Red! ich-Kister equation. The open square point

S is calculated from the Spencer et al. (1975) AG

f

K2 Si 2 0 5 (£)

data and Charles' Si

0

2 activity with the error bar reflecting

the AG^ uncertainty only. The triangular point was calculated

by Spacil and Luthra (1980) from the phase diagram.

561-64
No

PARTIAL

PRESSURE

(atm)

TEMPERATURE K

10

4 /T (K)

Figure 2 Comparison o model (open circles) and experimental Na-partial

pressures over SRM-621 glass (see table 1).

561-65
6 7 8 9

104 /TEMPERATURE (K)

Figure 3 Partial pressures of K and Na as a function of reciprocal

temperature for dolomitic limestone with wt. % composition:

CaO (30.1), MgO (21.3), Si02 (1.2), A1 2 0 3 (0.19), Fe2 0 3

(0.28), Co 2 (46.6), K2 0 (0.12), Na2 0 (0.01), SrO (0.01), MnO

(0.03), and Ti0 2 (0.02). The solid curve represents the best

fit to the Knudsen K pressure data (open circles); triangles

represent TMS K-pressures; and closed circles represent KMS

Na-pressures.

561-66
EQUILIBRIUM

CONSTANT

K

Figure 4 KMS data for the apparent equilibrium constnt as a function of

HCL pressure for the system,

Na2 0(glass) + 2HC1 (g) = 2NaCl(g) + H 2 0(g).

561-67
TEMPERATURE

DEPENDENCE

OF

NITROGEN

RAMAN

SPECTRA

A1ISN31NI 3AllV“l3d

561-68

Figure

5

Calculated

Raman

spectra

for N

2

as

a

function

of

temperature.
Time (min.)

Figure 6 Shrinkage (AL/L) vs time (log/log) plot for 0.5 pm powders

produced by extended ball -milling.

Figure 7 Shrinkage vs sintering time at 1400 °C for three anorthite

powders (log/log plot).

561-69
BaO

Figure 8 Phase diagram for the BaO-Al 2 0 3 -Ti0 2 system.

561-70
m

in

sf

iri

o

o

CD

v_Z3

O

v_

CD

CL

£

rr> C

O

CD

C

c

<

(y)q;6u9| sixd

t|

0

ti

561-71

Figure

9

Phase

transition

for

ZrTiO

PROPERTIES, STRUCTURE, AND STANDARDS FOR GLASS AND OPTICAL MATERIALS

Task 12154

Glass is a solid material, characterized by an unique combination of

properties and a distinct production technology. It is the product of a large, well -focused world-wide industry. With respect to production

technology, thermo-plasticity is the most unique physical property of

glass. It allows the production of glass objects by such high-speed

processes as casting, blowing, pressing, centrifugal casting, spinning,

drawing, and slumping. Although made from relatively abundant and

inexpensive materials, manufacture of glass requires high temperature

processing with its inherently costly problems of furnace corrosion, air

pollution, and fuel economy.

Unique user-related properties of glass are optical transparency, chemical

durability and low thermal and electrical conductivity. These properties

are the basis of the major bulk uses of glass which are architectural

glazing, optical components, containers, enamels, building insulation,

and electronic components. More novel applications of glass are solar

energy devices, lasers, fiber-optic devices, hosts for nuclear waste,

electronic substrates and insulation layers, computer displays, pH-sensors,

and several more defense and national security related applications.

The Glass Group is involved in the generation of basic scientific data

which relate to such fundamental processes as glass formation, glass

crystallization and phase separation. Such data are used by industry

and researchers throughout the world as guidelines for the development

of glasses located within glassforming boundaries, while having combinations of useful properties. This research, accomplished in part in

collaboration with guest workers and outside laboratories, is described

in more detail below under Subtask 1 (Physics and Chemistry of Glass).

In other activities of Subtask 1, the Group is further involved in

studying fundamental properties such as propagation of light under

conditions of pressure or in the multiple internal reflection mode

encountered in planar wave guides. The wave-guide mode was used to

measure thickness and refractive indices of glassy thin films synthesized

by co-deposition from molecular beams, confirming the applicability of

principles of glass formation. This study, aside from contributing to

the basic understanding of glass formation, promises also to yield novel

films without the deleterious effects of grain boundaries (light scattering,

chemical attack). The thin film synthesis and analysis facility designed

for this purpose has since found other uses which are described in

Subtask 5 (Preparation and Characterization of Thin Films).

The Glass Group of the NBS has a long tradition of close relation with

the U.S. glass industry through personal contacts and through the American

Society for Testing and Materials (ASTM) Committees on which representatives of the industry and members of the Glass Group are seated. Much

of the work of the Group reflects therefore directly the needs of the

glass-producing and glass-using industries. Activities in Subtask 2

(SRMs for the glass industry) relate directly to glass properties of

interest to glass production (e.g. , viscosity, high temperature resistivity)

or to glass usage (e.g., dielectric constant, thermal expansion). This

561-73
year, certification activities for a dielectric constant glass standard

were completed. This standard will aid the glass as well as the electronic

industry, which uses glass for a great variety of transparent and/or

insulating components.

An activity which arises both from the NBS's major mission in standards

and the Group's ability to synthesize glasses of unusual compositions is

the development of glass-based standards which benefit industries other

than glass producers or glass users. Glass, as a solidified liquid,

permits production of large pieces of solids, having an inspectable

homogeneity not available from other materials. Its unique structure

permits compositions spanning a wide range of stoichiometries. Furthermore, such homogeneous glasses can be easily formed into many shapes,

ranging from bulk pieces, fibers and microspheres to films, disks, and

cubes. Such SRMs, made by the Glass Group, generally serve analyticalchemical purposes, but are also calibrated for such properties as optical

fluorescence. Activities of this kind are described in Subtask 3 (Glass

Standard Reference Materials for Other Industries). A recent addition

to glass-based analytical standard materials are glasses for calibration

of biological tissue analyzers where certain normal and abnormal tissueelements are incorporated into a low Z-glass matrix.

The NBS Glass Group is well known for its ability to solve glass synthesis

problems, particularly if they relate to developing glasses with properties which are difficult to achieve, and/or to measure. Such activities,

listed under Subtask 4 (Special Glass Developments), are usually carried

out in response to requests from other government agencies. In some cases these agencies not only seek special expertise, but also wish to

retain NBS scientists as neutral experts where large expenditures or critical decisions are involved. A noteworthy development for this year

are novel glasses having unusual combinations of high modulus of elasticity and low thermal expansions. These glasses promise to be good candidates for forming the outer layer of composite glass fiber sensor leads,

protecting the signals in the fiber from spurious modulating due to

external pressure changes. Such fibers are desired for deep-sea applications such as hydrophones and data links.

The Glass Group continues to respond to a large number of glass-related

inquiries from the glass-using, glass-producing industry, the general

public, government agencies, universities, and research laboratories

which look upon NBS as a national focus in glass technology. The inquiries reflect to a certain extent national trends. Inquiries during the

last year covered such subjects as automotive safety devices, glass for

electronic microchips, solar energy devices, glass fibers for building

insulation, accidents involving glassware, and military infrared detectors

and accessories. Members of the Glass Group were also requested to

review export licenses for glass-related products and/or for technical

know-how of potentially strategic importance. A study of failures of

architectural glass components and their safety was undertaken for the

Architect of the Capitol.

Technical activities for each Subtask are described below.

561-74
Physics and Chemistry of Glass

Subtask 1 of Task 12154

D. H. Blackburn, D. J. Cronin, A. Feldman, L. H. Grabner, W. K. Haller,

D. A. Kauffman, D. M. Sanders, R. M. Waxier, and C. M. Scarfe 1

1 Guest Worker from the University of Alberta

Nucleation Kinetics in l_i 9 0-2Si0? Glass

The nucleation and crystallization of melts is a topic of continuing

interest in glass technology since it controls glass formation and can also be used to produce dense fine-grained ceramics of commercial importance. A study of heterogeneous nucleation behavior in Li 2 0-2Si02 glass was undertaken in an effort to obtain a better understanding of the

nucleation process. Li 2 0-2Si02 was chosen for several reasons. It is a simple glass yet forms the basis for commercially important glass ceramic

materials. This particular composition has frequently been used in

nucleation studies and has been well characterized with respect to

homogeneous nucleation. These results have shown that over the entire

nucleation range classical nucleation theory does not adequately describe

the nucleation behavior. This is in contrast to other simple silicates

which behave according to classical nucleation theory.

Experimental results reported in the literature on Li 2 0-4S i

0

2 using

platinum as a nucleation catalyst show a maximum in a plot of volume

percent crystal versus platinum content. Preliminary measurements at

NBS showed similar behavior for Li 2 0-2Si

0

2 glass. No adequate explanation

for this effect has been given. Therefore, to clarify this point and

provide accurate heterogeneous nucleation data for Li 2 0-2Si02 as a test

of classical nucleation theory and as a comparison with homogeneous

nucleation data a detailed study of nucleation in the Li 2 0- 2Si

0

2 glass

was carried out.

Due to the catalytic activity of the platinum particles in bringing

about crystallization, a new technique had to be developed to determine

the number of crystals formed in a given time period. Normally this is

done by nucleating at a given temperature after which the sample is

taken to a higher temperature to grow the nuclei to an easily observable

size. This requires that the nucleation rate vs temperature, and crystal

growth rate vs temperature curves being separated so that there is no nucleation at the growth temperature.

The effectiveness of platinum particles in nucleating crystals in

Li

0

2

* 2Si

0

2 glass causes a shift of the nucleation rate curve to higher

temperature, making the usual technique of obtaining nucleation data

unusable.

The technique developed requires measuring the size distribution of

crystals in the glass and the crystal growth rate at the temperature

used. The number of crystals formed at any time can then be determined.

The various nucleation parameters can be evaluated by fitting the data

to the appropriate equations for nucleation.

561-75
It is also of interest to compare the number of crystals formed with the

number of available heterogeneous sites to determine if indeed all sites

produce crystals. A method was developed where the platinum particles

can be separated from the glass and the total number of particles/unit

volume of glass can be determined. The results show that there is good

agreement between the number of crystals found and the number of platinum

particles available, indicating that all particles are actual nucleation

sites.

Scanning electron microscopy examination of the early stages of crystallization showed that after etching with a weak hydrofluoric acid (HF) solution a thin layer of material at the platinum interface has been removed.

One possible explanation is the presence of lithium metasilicate as the

initial phase formed. Such a reaction has been suggested in the literature on the basis of indirect evidence. Other investigations report no sign of Li 2 0*Si02 during the crystallization of Li 2 0-2Si02

.

High precision x-ray diffraction analysis, carried out at Alfred University, has shown the presence of small amounts of Li 2 0 - Si

2 phase during

the early stages of crystallization. This is the first direct evidence

for this effect. This requires a re-evaluation of the analysis of nucleation data to include this reaction.

Viscosity of Melts in the CaQ-MgO-NagO-Al^Oa-SiO?, System

This work is being carried out in collaboration with Dr. C. M. Scarfe of

the University of Alberta, Canada.

Melt- viscosity is an important property of glasses, both from the scientific and the technological standpoint. The viscosity is an expression

of the melt structure and in particular of associated or polymeric

states which appear to be a prerequisite for easy glass formation. The

current work involving viscosity measurement along the diopside

(Ca0*Mg0*2Si02 )-albite (Na2 0*Al 2 03 *6Si02 ) join is an extension of earlier

work on the diopside anorthite (Ca0-Al 2 03 -2Si02 ) binary. These systems

are of interest to glass technologists and geologists for data obtained

on specific compositions but also for the knowledge that can be gained

on the general behavior and structure of silicate melts.

The work on the diopside-anorthite system has been described in a paper

which has been submitted for publication in American Mineralogist.

The results on the diopside albite system show an increase in viscosity

at constant temperature as albite is substituted for diopside. This

involves an increase in Si

2 in the melt as well as Na2 0 and A1 2 03

replacing CaO and MgO. In terms of structure this is viewed as moving

from a depolymerized structure to a three dimensional network type structure. The rate of change of viscosity increases going from diopside to

albite. Further interpretation of the viscosity data and correlation

with structural information gained from vibrational spectroscopy will be

carried out in the near future.

The high temperature viscosity data obtained for the melt of albite agree

well with values in the literature. Literature values for the low

! 561-76
temperature, 800 to 1000 °C, viscosity data, however, show considerable

disagreement. The viscosity of albite will be measured in this temperature range in an attempt to clarify the situation.

Vapor Co-deposition Pathways to Dense Glass-like Solids

The traditional way of forming glasses by undercooling of melts is not

the only way to produce dense amorphous solids. We are exploring the

production of glass- like structures by co-deposition from the vapor

phase. This study has general interest for the process of glass formation.

In addition, it has some important practical implications. Currently

the weakest parts of high-energy laser systems for military and energy

applications are the reflection and anti ref lection coatings which fail

when subjected to high energy pulses. The magnitude of such pulses is

significantly lower than can be transmitted through the bulk glass

elements. The exact mechanism for the failure is still poorly understood,

but there is growing evidence that the presence of grain boundaries is

at least partly responsible. Films produced in our study are free of

grain boundaries and it is hoped that such films may have improved

hardness to high energy laser damage.

In earlier work by our Group, adding 19 mol % Si02 to a Zr02 matrix

produced a film which was amorphous as determined by x-ray diffraction

and scanning electron microscopy. Silica was chosen because it is a well-known glass-former in bulk glass formulations. The requirement of

using a traditional glass-former, however, restricts the possible values

of index of refraction for resulting mixed films. This restriction is

particularly severe for applications requiring high index of refraction.

For this reason, the effects of adding a non-glass forming component

(MgO) to a Zr02 matrix was studied. Based upon examination by x-ray

diffraction it appears possible to produce glassy films using a mixture

of non-glass-formers. However, the concentrations of required additions

are higher (50 mol %) and the probable mechanism for glass formation is

different. These results are discussed in more detail in a SPIE Proceedings article based on a talk given in Arlington, VA, in May 1982. In

addition to exploring the influence of crystallinity on laser damage

resistance, we have a longer-term goal of producing gradient index anti re- flection coatings by coevaporation. As discussed in the section "Preparation and Characterization of Thin Films" below, the capability of producing

gradient refractive index coatings by computer-controlled coevaporation

is under development. Since such coatings can, in theory, eliminate the

abrupt breaks in the refractive index found in currently employed antiref lection layered structures, they may have increased resistance to

high-energy laser damage.

Finally, we are currently calibrating the electron spectroscopy for chemical analysis (ESCA) facility to permit an accurate quantitative analysis

of mixed oxide films. This will allow rapid comparison of the mixed vapor

concentration with the concentration of the resulting thin films. Such a comparison should prove useful in determining if preferential bonding

occurs in the film. Clustering has been observed by other workers using

field ion microscopy and is highly significant in explaining breaks in

property curves in bulk glass-forming systems.

561-77
Dynamic Synchrotron SAXS Investigation of Subliquidus Phase Separation

in Glasses

This is a collaborative project between the Stanford Synchrotron Radiation

Laboratory (SSRL) and the NBS.

Phase separation is an important phenomenon in glass formation and the

precise kinetics and mechanisms are still not fully understood. Most

understanding so far has come from studies on phase separated melts

which were chilled to freeze the structures and to make them observable

with such techniques as electron microscopy. The high x-ray intensities

available from synchrotron sources opened the possibility for j_n situ

studies of the early stages of phase separation.

Time-resolved small angle x-ray scattering (SAXS) studies were first

performed on Na2 0-B 2 0 3 -Si0 2 glasses. These glasses scattered relatively

weakly but demonstrated the ability of the SAXS system for investigating

the phase separation. The change in the SAXS pattern recorded every few

seconds could be readily monitored as the sample temperature was manipulated and the composition inhomogeneities grew or dissolved. It was

found, however, that the scattering from the borosilicate samples was

not reproducible as they were repeatedly cycled above and below the

miscibility temperature. This was attributed to composition drift due

to preferential evaporation.

To improve on the contrast in the glass, it was decided to develop phase

separating compositions containing heavy elements such as BaO. Promising

compositions in the Ba0-K2 0-Si02 (BKS) system were located. Although it was difficult to produce homogeneous samples of glasses with compositions

close to the line of critical points of the metastable immiscibility

dome (due to high viscosities at achievable temperatures), homogeneous

samples were made of compositions with slightly less silica. Several

major improvements were made to the SAXS detector system. To provide

compatibility with existing facilities at SSRL, the hardware and software were modified for use with a PDP11 computer. An unscreened 1024-pixel

Reticon photodiode array, which absorbs x-radiation directly in the

photodiodes, was installed as the sensing element in place of the phosphor/

fiber-optics-covered array used previously. This resulted in an order

of magnitude improvement in sensitivity, giving an instrumental noise

equivalent to less than 3 (9 keV) photons/pixel/readout and saturation

at around 5000 photons/pixel/readout. The extra sensitivity improved

the quality of the data obtainable during the earliest stages of phase

separation when scattering was very weak.

Experimental runs with a Ba0-K2 0-Si02 glass showed that the scattering

during early-stage phase separation was intense enough to characterize the

process and was reproducible. A redesigned sample furnace was installed

to minimize temperature gradients in the sample. Data were obtained for

two compositions (BaO: 0. 05,K2 0: 0. 05 , S i

2

: 0. 90 and BaO: 0. 06 ,

2 0: 0. 06 ,Si02

: 0.88 mole fractions) at several holding temperatures. The absolute efficiencies of the array and incident intensity monitors were measured so that the data may be expressed in units of differential cross-section per

unit sample volume for comparison with theory. Analysis of the data and

system documentation are presently underway.

561-78
Piezo-optics

Relatively few piezo-optic measurements have been made at wavelengths

above 2.5 pm and most of these data are at discrete laser wavelengths.

With so few data it becomes difficult to test any of the theories that

have been developed for predicting photoelastic dispersion due to the

effect of strain on the infrared-active transverse-optic (IRTO) phonon.

This is in contrast to the relative success of fitting piezo-optic data

to strain-induced electronic effects such as the effect of strain on the

energy bands and free carriers of semiconductors. Only recently have

piezo-optic measurements been made at a significant number of wavelengths

and most of these measurements have been made at this laboratory. This

year we have performed piezo-optic measurements on CaF 2 , BaF 2 , SrF 2 , GaAs, and CdF2

. Almost all of these materials are technologically

important as infrared transmitting materials.

In our earliest work we had reported on room temperature measurements of

all the piezo-optic constants q ll5 q 12 , and q 14 of CaF 2 and SrF 2 at the

discrete laser wavelengths 0.6328 pm and 3.39 pm. In later work we had

extended the piezo-birefringence measurements further into the infrared

where we observed a large dispersion due to the proximity of the IRTO

phonons. The data had been fitted to a three parameter oscillator model

based on the strain dependence of the IRTO phonon frequency and oscillator

strength.

Most recently, a sensitive detector became available to us so that

improved measurements could be made in the wavelength range 5.5 to

11.0 pm. We therefore repeated the piezo-birefringence measurements at more wavelengths in this range. The results were generally in good

agreement with our earlier measurements. All the data have been fitted

to an improved model of piezo-birefringence originally presented by

Humphreys and Maradudin and subsequently by Bendow, Gianino, Tray,

and Mitra. We find that the principal contribution to the dispersion

comes from the strain-induced splitting of the IRTO mode. Estimates

have been made of the strai n-i nduced relative anisotropy of the transverse

effective charge. Although the data can be fit to the basic phenomenological model of HM, no microscopic theoretical calculations are available

to compare with the computed parameters. Such calculations have been

made for GaAs and, hence, similar measurements have been conducted on GaAs; the measurements and these analyses were discussed in the previous

annual report.

Because of the similarity of the infrared absorption spectrum of CdF 2 with that of CaF 2 , we decided to measure the infrared piezo-birefringence

of CdF2

. Crystals of CdF 2 were purchased from a commercial supplier.

Two specimens were prepared from these crystals, one oriented for stress

along the [001] crystal axis, the other for stress along the [111]

crystal axis. The [001] specimen was a rectangular prism approximately

6 x 7 x 17 mm; the [111] specimen was a rectangular prism approximately

8 x 8 x 22 mm.

The refractive index of CdF2 was measured at nine wavelengths in the

visible and at 1.15 pm by means of a V-block refractometer. The data

561-79
were fitted to a power law expression of the form n

2 = AA2 + B + CA-2 + DA-4 + EA-6 + FA-8 with a standard deviation of 1.4 x 10~4

. A fit to

the above equation was also obtained by eliminating the point at 1.15 pm;

the coefficients changed in value and the resultant standard deviation

was 7 x 10~ 6. The measured values differed by 0.005 from values reported

in the literature; this difference is attributed to differences in

crystal purity.

The piezo-optic constants q n , q 12 , and q 14 have been measured in the

visible at 0.6328 pm. The coefficients show a considerable dispersion

in the infrared which follows closely the dispersion of the corresponding

coefficients of CaF 2.

Propagation, Attenuation, and Thickness Measurements in Thin Films

The refractive index and thickness of a film prepared by coevaporation

(79% MgO, 21% Si

0

2 by volume) was measured by the prism coupler method.

Measurements of the transverse electric (TE) and transverse magnetic

(TM) mode coupling angles were made at three wavelengths of the argon- ion

laser. Computer programs were developed for fitting the prism coupler

data to the thin film mode propagation equations in order to calculate

the refractive index and thickness of the film. The prism coupler

method is a very precise means for obtaining the refactive index of thin

films. Thus we were able to measure dispersion in the refractive index;

furthermore, the accuracy was sufficient to measure a birefringence on the film which we attributed to internal stresses. A signature for the

birefringence was observed in the m-line spectrum of the film, in which

the order of the TE

q and TMq modes was interchanged as compared to their

expected order in an isotropic film. The measured values of refractive

index agreed extremely well with a Drude model calculation based on the

estimated volume fraction of each of the film constituents.

An intercompari son of techniques for measuring the thicknesses of films

of ~ 1 pm thickness was made based on measurements reported in the

literature and measurements conducted at the National Bureau of Standards.

Six techniques were compared—stylus profiling, dual beam interferometry,

multiple beam interferometry, prism-coupler method, ellipsometry, and

channeled spectra. All of the techniques are of comparable accuracy;

dual beam interferometry and stylus profiling have a conservative accuracy

of 2.5 percent for 1 pm thick films; ellipsometry, channeled spectra,

and the prism-coupler method are accurate to about 1 percent; multiple

beam interferometry is accurate to about 0.5 percent. The stylus instrument and the dual and multiple beam i nterferometry require an opaque,

reflecting specimen; the prism-coupler method, ellipsometry, and channeled

spectra require transparent specimens; stylus profiling and the prismcoupler require contact with the specimen.

At the present time we are designing and constructing apparatus to measure optical scattering due to micro-irregularities in thin films.

Two systems are to be built; a total integrated scattering (TIS) apparatus

to measure all the radiation scattered back within a Zn hemisphere,

excluding radiation within 3° of the normal; an angular scanning apparatus

to measure scattered radiation in the equatorial plane as a function of

561-80
the scattering angle. The TIS will allow for rapid intercomparison of

specimens prepared under various deposition conditions. The angular

scanning apparatus will provide information about the dimensional scale

of the micro- irregularities in the film; the smaller the scale of the

irregularities, the larger the scatter at large scattering angles.

Standard Reference Materials for the Glass Industry

Subtask 2 of Task 12154

M. J. Cellarosi, D. J. Cronin, and W. K. Haller

Dielectric Constant SRM

Activities leading to the certification of a dielectric constant glass

standard have been completed. This work involved the completion of

interlaboratory comparisons with industrial laboratories, statistical

analysis of data, test methods and procedure improvements, sample preparation for SRM packaging, and issuance of SRM certificate and related

publicity literature.

This project was undertaken at the request of ASTM Committee C14.04 on Physical and Mechanical Properties of Glass principally to resolve

serious measurement discrepancies for the glass dielectric constant that

existed in industry. SRM 774 for the dielectric constant and related

loss characteristics now issued for sale by NBS will primarily support

the expanding role of glass in electrical /electronic applications. Such

applications include: envelopes for devices, substrates, encapsulation,

windows for electromagnetic waves, capacitors, insulation, etc. The SRM

will also help in energy conservation efforts (e.g., low loss insulators

and dielectrics), and in the evaluation of glass and other material

properties, such as dielectric breakdown, moisture content, deterioration,

etc. The standard is also expected to be of interest to the plastics

industry as the inherent long-term stability of glass is superior to

that of plastics for calibration purposes.

Glass High-Temperature Resistivity SRM

This project is listed as one of the priorities by the ASTM C14 Committee

on Glass SRM development.

Glass resistivities as a function of temperature in the molten range are important parameters for effective utilization of electrical power, for

increased productivity, higher glass quality, and in reduction of air

pollution from glass furnaces. Glass resistivity is also a very important

factor in the design of melting process equipment and this SRM will be

of benefit to the glass industry as an increasing number of melting

operations are converted to electrical power.

Procedures and samples (SRM 711, Viscosity Standard) were distributed to

the participating industrial laboratories. A second round-robin now in

progress utilizes procedures employed in high temperature viscometry.

These procedures enable the generation of simultaneous resistivity/viscosity data. Viscosity SRMs provide the necessary temperature calibrations.

561-81
A new measuring bridge was purchased, and other instruments and equipment

in the Division and elsewhere at NBS were evaluated for possible use. Calibrations and equipment modifications are in progress. Standard KC1

aqueous solutions are used in the calibrations and for the determinations

of the cell constant required for the calculation of resistivity.

It is important to note that SRM 711 glass is already certified for

electrical resistivity in the lower temperature range, and for dielectric

constant and associated ac loss characteristics. Therefore, SRM 711,

when it is certified for resistivity in the molten range will cover a broad spectrum of electrical properties.

Viscosity SRM

In anticipation of replacing viscosity SRM 710 (soda-lime-silica glass)

a new high temperature viscometer is being constructed for use in the

certification process. The viscometer utilizes a commercially available

torque measurement system and a furnace designed at NBS. To simplify

operation of the instrument a new torque meter was obtained that will

allow driving the inner cylinder and measuring the resultant torque.

Previously, it was necessary to rotate the crucible which presented a number of experimental difficulties. With the new torque meter these

difficulties can be eliminated. Furnace construction and refinement of

mechanical details will be carried out to allow ample time for calibration

prior to SRM certification.

Other SRM Development Activities for the Glass Industry

In cooperation with ASTM Committee C14.91 on Standard Reference Materials,

and a glass industry supported part-time research associate, NBS is

involved in developing a series of six glass SRMs which had been established as priorities by industry. An update on the progress and status

of these candidate SRMs follows.

Thermal Expansion Standard with a Coefficient Approximately 90 x 10~7 /°C

Soda- lime glass rods (Kimble R-6) were made by the Kimble Division of

Owens-Illinois and received at NBS. Glass homogeneity as determined by

interlab testing is excellent. However, preliminary expansion measurements

show that the expansion coefficient is sensitive to thermal history

below 300 °C. This effect may rule out R-6 as an SRM. Other compositions

are being considered.

Glass with a Well-characterized Ferrous/Ferric Ratio for an Analytical

Standard

A draft of a wet-chemical consensus method for the determination of

ferrous iron was developed. Interlab testing is in progress using an amber soda-lime and a borosilicate glass to determine the ferrous/ferric

ratio by difference between iron in the ferrous state and total iron.

NBS SRMs 620, 621, 1830, and 1831 are also being used to aid in establishing an ASTM Test Method.

561-82
Soft Boros i 1 i cate Glass for an Analytical Standard

A glass composition supplied by Johns-Manvi 1 le was processed by Corning.

Approximately 4800 wafers made by the Corning Clearform process were received at NBS. Interlaboratory x-ray fluorescence chemical homogeneity

evaluations are in progress.

High Alumina Sand for an Analytical Standard

A candidate sand was prepared by grinding a high alumina sand to 98 percent

minus 200 mesh. This flour was magnetically separated at Owens-Corni ng

to remove iron. Evaluations of this material, however, proved that the

material was not acceptable and was therefore rejected. Feldspar and

silica flour were blended, but even this formulation had to be rejected

because it had a too broad particle size range. High alumina sand, provided by Santa Cruz Aggregates Company, was ground by Ferro Corporation

and shipped to NBS. Interlaboratory testing is in progress to analyze

chemical homogeneity and suitability as candidate SRM.

Multicomponent Glass for Analytical Standard

This glass is being prepared by Corning, and it will be formed in the same manner as indicated for the borosilicate glass above, after the

Clearform method is proven to be sound.

Fused Quartz Annealing Point SRM

The quartz product business is an expanding activity as new uses for

quartz are developed. Quartz performance is highly dependent on the

chemical and physical properties of the material. One of the critical

properties is viscosity. New developing applications of quartz include

the semiconductor crucible business, and fiber optics technology. This

SRM has been proposed by ASTM Subcommittee C14.04 on Physical and Mechanical Properties of Glass as a logical extension to other NBS standards

for viscosity. Quartz rods made by General Electric have been distributed

by NBS to establish the homogeneity of the material for a fused quartz

annealing and strain point SRM.

Density SRMs

Density is a very important property for quality control in glass production. Eight industrial laboratories have indicated a strong interest in

establishing glass density SRMs. ASTM Committee C14.04 on Physical and

Mechanical Properties of Glass has requested that NBS certify the density

of some existing SRMs. Three glasses were identified as likely candidates:

viscosity SRMs 711 and 717 and liquidus SRM 773.

Glass Standard Reference Materials Liaison

The Glass Group maintains broad relations with industry, research and

development organizations, and academia concerning the scientific and

technological progress in glass and related products. Active participation is extended to various standards and measurement bodies. Glass

Group personnel hold offices in the International Commission on Glass

and ASTM Committee C14 on Glass and Glass Products.

561-83
Resource Recovery and Utilization

This project has been pursued in response to the Resource Conservation

and Recovery Act of 1976. In this Act, NBS is directed to provide

guidelines for the development of specifications and related standardization for materials recovered from waste. NBS work and funding up to

this fiscal year have been coordinated through the Office of Recycled

Materials and will be terminated this year.

One major benefit for recycling glass is energy savings. Other benefits

are extension of furnace life linings and plant emission control.

Activities involved the characterization of recovered glass at various

reclamation facilities, large-scale production runs, plus the development

of specifications and test methods applicable to glass recycling in

fiber glass production. NBS has cooperated with ASTM Committee E38 on Resource Recovery, the glass industry, reclamation facilities, and other

organizations, principally in activities on specifications, test methods,

and interlaboratory comparisons.

Cooperative testing activities by NBS, the National Center for Resource

Recovery, Owens-Illinois, and EG&G were carried out for glass recovered

as the Recovery I reclamation facility in New Orleans, LA. Laboratory

results covering refractory and magnetic/non-magnetic contaminations,

organic contamination, particle size, melt evaluations, and viscosity

are used as inputs in preparing for a large-scale production at a glass

container plant in Atlanta, GA. The correlaton of lab data with the actual

production output will be used to design second generation glass recovery

plants.

Glass SRMs for Other Industries

Subtask 3 of Task 12154

D. H. Blackburn, D. J. Cronin, and D. A. Kauffman

Glass Standards for Small Particle Chemical Analysis

Glass has many properties which make it uniquely suitable for analytical

standards in microbeam analysis. Numerous very different oxide glassforming systems give a variety of matrices to select from in order to

minimize interfering and overlapping responses which can confuse interpretation of analytical data; furthermore, there is an overall matrix

effect which can now be evaluated and interpreted. As an example,

instrument responses will be quite different for a given element when it

is incorporated in a Te02 -Ba0 matrix or in a B 2 0 3 -Li 2 0 matrix.

Other desirable features of glass for this application are excellent

physical and chemical stability, lack of structure, and the fact that

glass can be made extremely homogeneous even with a large number of

elements present. Furthermore, one of the most useful features is that

glass can be fabricated into a variety of shapes and sizes from the same parent glass melt of known composition. Bulk specimens can be fabricated

by conventional grinding techniques, continuous fibers can be formed in

kilometer lengths with diameters as small as 3 micrometers, spheres

561-84
ranging in size from 100 micrometers to submicrometer diameters, and

o thin films below 2000 A in thickness can be produced.

A major effort during FY82 was the construction of a facility for the

preparation of glasses containing the radioactive elements uranium and

thorium. This will enable the Glass Group to produce glass melts and

prepare micrometer and submicrometer spheres of radioactive glass in a safe environment. The facility is near completion and will be in operation

before the end of FY82. Work has continued on the production of glass

standards of various compositions for the Center for Analytical Chemistry.

A new Standard Reference Material for Microprobe Analysis is in the

process of being certified. This standard, SRM 471, will consist of 15

glasses and is an expansion and upgrading of Research Material No. 30.

It will consist of five glasses in the systems Pb0-Si02 , Ge02 -Pb0,

P 2 05 -Al 2 03 -Mg0 , Si0 2 -Ba0-Zn0, and B 2 0 3 -Al 2 03 -Li 2 0 giving very different

matrices. Five other glasses with the same matrices but doped with A1

B, Zr, Ti, Ce, Ta, Fe, and Li and another series doped with Zr, Ti, Ni

Eu, Mg, Ba, P, Ge, U, Th, and Cr. The compositions were carefully

chosen for microprobe use to give a maximum amount of analytical standards

information.

Analytical Standards for Biological Materials

Further progress has been made in extending the use of glass analytical

standards to the analysis of biological materials. This work is a cooperative effort in conjunction with groups at the National Institutes of

Health. A lithium borate glass matrix was selected for the work since

it is necessary that the matrix have a low Z similar to animal tissue.

Elements such as K, Ca, S, I, F, N, and Hg have been incorporated into

various lithium borate matrices. Results are being published in the

Journal of Microscopy in a paper entitled Low Z Glass Standards for

Biological X-ray Microanalysis, by C. E. Fiori and D. H. Blackburn.

Other work was presented at the 17th Annual Conference of the Microbeam

Analysis Society, August 1982, in Washington, DC. A paper is in preparation entitled Energy Dispersive X-ray Microanalysis of Biological

Specimens by M. C. Foster, W. A. Hagins, and D. H. Blackburn, and is

to be submitted to the Journal of Analytical Chemistry.

Mi crospectrof 1 uorometri c Standards

Expanding use of fluorescence in immunochemical and cytological analysis

as well as particulate analysis has made development of microfluorescence

standards of increasing importance. A series of stable luminescent

microspheres was developed using a silicate matrix glass doped and

codoped with europium and terbium. Microspheres formed from these

glasses were in the size range of 5 to 50 pm in diameter. This work was presented at the Pittsburgh Conference and Exposition on Analytical

Chemistry and Applied Spectroscopy, March 1982, at Atlantic City, NJ. A more detailed presentation will be published in the Journal of Analytical

Chemistry entitled Inorganic Ion Doped Glass Spheres as Microspectrofluorometric Standards by R. A. Velapoldi, D. K. Hancock, J. R. DeVoe, and

D. H. Blackburn.

561-85
Nuclear Waste Leachability Research Material

Though the NBS Nuclear Waste Program was discontinued at the start of

FY82, contact has been maintained with the nuclear waste community,

particularly with regard to the need for standards. A leachability study

was carried out in conjunction with H. M. Kingston and M. S. Epstein

of the Center for Analytical Chemistry. The purpose of the test was two-fold: one purpose was to investigate the effect of composition

variation on leaching behavior of the glass composition which had been

proposed as a research material; the second purpose was to tighten MCC-1

test procedures to improve the quality of data obtained. The results of

this test were successful on both counts.. The leach results for replicates

of the same glass showed uncertainties that were approximately equal to

the uncertainty of the analysis for a given element.

The high quality analytical results allowed a maximum amount of information to be obtained concerning composition variations. This showed that

increasing Na, B, Cs, and Mo decrease the glass durability, while Ti,

Sr, Nd, and Ce improve the glass durability.

The results of this study were reported at the Materials Characterization

Center Workshop on Leaching Mechanisms held at Gaithersburg, MD, May 19-21,

1982.

Special Glass Developments

Subtask 4 of Task 12154

D. H. Blackburn, D. J. Cronin, A. Feldman, L. H. Grabner, W. K. Haller,

D. A. Kauffman, and R. M. Waxier

Laser Glasses

Collaboration of the Glass Group with the Lawrence Livermore Laboratory

(LLL) has continued and expanded in scope. Over 100 different glass com- positions were prepared of various compositions in silicate, phosphate,

and borate systems, and doped or codoped with rare earth transition metal

oxides. These glasses are used in the LLL continuing investigation of

glass laser systems. In addition to the ongoing work, a new project was started in mid-year. This involves developing a borate laser glass in

which Yb is the active species. Earlier studies showed that Yb in a borate glass matrix may be suitable as a laser system.

This project involves three phases. The first phase is to produce a series of simple binary glasses containing Yb to investigate the effect

of the different modifying ions on the various optical properties of

interest. These include glasses of alkali and alkaline earth borates in

addition to borates of A1 , Y, and La. These glasses have been delivered

to LLL for optical property measurements.

The second phase of the project involves the investigation of the effect

of water on fluorescence behavior of Yb. Other work has shown that the

presence of water in the glass adversely affects the fluorescence behavior

of Yb. This portion of the project involves preparing a series of

glasses varying the water content to obtain quantitative information on

561-86
this effect. To accomplish this it is necessary to develop a direct

technique to determine water content in borate glasses. This work is

currently underway.

Once the composition effects have been determined for the individual

modifier ions the third phase involves development of a glass composition

that maximizes laser properties and can be made in large pieces of

optical quality. This involves trade-offs in optical properties, chemical

durability, and glass-forming ability.

Glasses for Fiber Optic Sensors

At present there is considerable interest in the use of fiber optics for sensors of physical parameters, such as temperature, pressure, electric

fields, and magnetic fields. The Navy has a particular interest in

developing acoustic sensors. The Naval Research Laboratory (NRL) has

therefore requested that NBS aid in the development of glasses for fiber

optic sensor materials and the characterization of these glasses as to

elastic moduli, thermal expansion, thermo-optic constant, and photoelastic

constants.

The fiber-optic sensor system is conceived as being composed of two parts:

the sensor itself which is located a long distance from a monitoring

station, and fiber optic leads that connect the sensor to the monitoring

station. The emphasis of our program is on materials to produce fiberoptic leads that are insensitive to pressure and temperature fluctuations.

The fiber optic leads are to pass through regions of the ocean that are subject to such fluctuations. It is important that the optic path of

propagation in the fiber core be immunized against these fluctuations in

order to minimize optical noise in the sensor system.

At present, the main emphasis of the program is to produce cladding

glasses that lower the pressure sensitivity of the core. Work at NRL

has shown that a cladding material with a high Young's modulus acts to

minimize the effects of pressure on the fiber core. We have now produced

a total of 19 glasses whose Young's moduli exceed the target value of

9.5 x lO 10 N/m 2

. Furthermore, we have measured the linear thermal

expansion coefficients of these glasses and have found some to have very

small values (a < 3 x 10" 6 /K at 20 °C). This result is highly desirable

because when claddings of these materials are fused to core materials,

made predominantly of fused silica, stresses due to differential thermal

contraction will be minimized, thus increasing the probability of success- fully drawing a pressure insensitive fiber. At present we are preparing

a cylinder of cladding material made from one of the glasses we have

produced which is to be used in a test drawing of a pressure insensitive

fiber at a commercial vendor.

In addressing the second problem, the temperature insensitive fiber,

work at NRL has shown that temperature insensitive fibers would have a core with a small thermo-optic coefficient at constant density (8n/8T)p.

We have conducted a literature search which suggests that (8n/8T)p would

be small in borate glasses, phosphate glasses, and glasses with a high

561-87
fluoride ion content. In addition, we have determined (8n/8T)p for

three commercial athermal glasses but have found the values in all the

glasses to be rather high.

Fluorescence Standards for the U.S. Post Office

Two glass development programs are currently underway for the U.S.

Postal Service. Both involve producing fluorescent glasses to be

used as standards for the calibration of automatic letter cancelling

equipment.

The first project involves development of a material showing high intensity

red fluorescence for use with existing equipment. Eu ions are used as the active material. To obtain the required intensity it was necessary

to incorporate the Eu in a Y2 0 3 matrix. To obtain the finished product

the Eu-doped Y2 03 powder is mixed with fine glass powder, pressed, and

sintered. This provides a dense material giving a smooth surface finish

that can be easily cleaned and the fluorescent intensity can be accurately

controlled by the amount of Eu-doped Y2 0 3 incorporated in the glass

matrix.

The second project calls for development of four different materials to

be used in a new calibration device under development at USPS. The

materials required are a green phosphor, red phosphor, red fluorescent,

and one material showing no fluorescence. The intensity levels required

are such that the first three materials can be produced directly from

glass melts.

Preparation and Characterization of Thin Films

Subtask 5 of Task 12154

E. N. Farabaugh, J. L. Fink, D. M. Sanders, M. E. Wilke, S. A. Hurwitz,

K. M. Summers, and A. Tegtmeyer

The facility for the production and characterization of thin films by

coevaporation has been operated during the past year in four research

areas: glass formation in multi-component thin films, chemical reactions

which may lead to stress corrosion in ceramics, protective films on metals, and thin film mechanical properties.

To carry out these studies, it has been necessary to enhance the capabilities of all of the subsystems of the facility. Simultaneous with the

system improvement, we have carried out preliminary experiments in each

research area. These have established experimental feasibility, and

determined the direction of future experimental work. The results of some of this work have been published.

System Improvement

The primary system modifications last year involved the carousel-loadlock

chamber and the surface analysis chamber. In addition to establishing a base pressure in the loadlock of better than 1 x 10-9 mbar using a combination of a liquid nitrogen trap and bakeout to 250 °C, we installed

561-88
the capability of heating substrates in the loadlock using quartz lamps

to temperatures in excess of 600 °C. This modification should permit us to anneal thin films deposited at pressures of 1 x 10“ 8 mbar in still

better vacuums to attempt to dislodge adsorbed water and other impurites.

It is our hope that such a treatment will produce films having a pristine

chemical structure for subsequent stress-induced reaction studies.

The computer software for the automation of the surface analysis system

has now been installed. In order to permit the use of the Hewlett-Packard

System HP-1000 minicomputer for other applications, it was necessary to

generate the software purchased from the supplier into a custom designed

operating system. In addition, a data acquisition interface to monitor

and control all aspects of the deposition process including residual gas

pressures, individual deposition rates, and deposition substrate temperatures has been delivered. In the next year, we will connect the interface

to the deposition hardware and monitoring equipment and write computer

programs to permit the computer to store all process parameters for

every thin film produced. This system will also provide computer-driven

control signals to permit gradient index mixed oxide films to be deposited.

During the year, an electron flood gun for charge compensation during

ESCA and ion scattering spectroscopy (ISS) measurements was installed. A

device for ijn situ deposition of a gold spot on any substrate for absolute

electron energy calibration was designed, constructed, and mounted between

the loadlock and the surface analysis chamber. When used together, the

electron flood gun and the gold spot evaporation capability permit accurate

determination of binding energies of dielectric samples.

Finally, we acquired and installed a dual anode x-ray source for the

ESCA system. This will allow us to quickly distinguish between photoelectron peaks and Auger peaks excited by the x-ray irradiation.

Noncrystalline Optical Coatings

This work has been discussed above under "Physics and Chemistry of

Glass" and "Optical Properties of Materials."

Fracture Studies

In order to understand the role of the gaseous environment upon the

reactions leading to stress-induced failure in ceramic materials, it is

first necessary to understand the nature of the chemical reactions which

can take place at freshly produced surfaces having stress-dependent

reaction rates. Freshly produced fracture surfaces are a reasonable

model for the material which is immediately in front, of an advancing

critical flaw. This work is being carried out with the Fracture and

Deformation Division (562).

To meet the above objective, short rod specimens of Si

2 , MgF2 , and

soda-lime-silica glass were prepared. These specimens were subsequently

fractured in the loadlock under vacuums of 1 x 10-9 mbar. The freshly

fractured surfaces were then characterized using both angle resolved

ESCA and normal take-off angle ESCA with computer controlled data collection and subsequent peak analysis. Finally, the resulting fresh fracture

561-89
surfaces were exposed to air and water vapor prior to a second ESCA

analysis. From the resulting ESCA spectra of the 0^ s and 0 Auger peaks,

oxygen bonded to silicon atoms can be distinguished fron oxygen bonded

to hydrogen atoms. The differences are, however, subtle and will

require the calculation of the peak's second derivative to permit stressdependent reaction rate studies. A small program to make such calculations

will be written shortly.

In the fracture of MgF 2 , we observed both oxygen and carbon ESCA peaks

using the angle resolved (surface sensitive) mode even at nominal vacuums

of 1 x 10~ 9 mbar. Since monolayer coverage requires one hour with unit • sticking coefficient at this vacuum, it is speculated that the observed

peaks resulted from adsorption of C0 2 or other gases from contamination.

This contamination may stem from gases released from the bulk material

in the fracture process. For this reason, the MgF2 experiments will be

repeated using a liquid N 2 cooling coil which has been installed in the

loadlock chamber. In either case, the observed 0 and C peaks were substantially diminished when the fresh MgF 2 fracture surface was allowed

to remain in the surface analysis chamber at 1 x 10 -11 mbar vacuum

overnight. This implies a physical adsorption mechanism.

In the last series of vacuum fracture experiments, ammonia was introduced

into the loadlock in an attempt to observe a N-^ s ESCA peak in the angle

resolved mode. Ammonia was chosen because experiments had indicated

that this reactant causes slow crack growth in Si02

. In addition, it was speculated that its reaction with the Si0 2 surface could be monitored

if the N^

s ESCA peak could be observed. Since N 2 is not normally adsorbed

on ceramic surfaces under UHV conditions, the ESCA peak constitutes

a new peak for monitoring stress-dependent reaction rates. Because it

is an entirely new peak rather than a shoulder on an existing peak as in

the oxygen Auger case, such an approach provides distinct analytical

advantages for monitoring changes in reaction rates with stress. In

addition, this reactant should not require such stringent vacuums as are necessary in monitoring changes in the oxygen Auger shoulder associated

with hydroxyl oxygen.

In the first series of experiments with ammonia it was discovered that

the N^

s peak could be observed in angle resolved ESCA if signal averaging

is employed. In order to produce high quality spectra it was necessary

to scan over this one peak for times in excess of 15 minutes with existing

equipment. The computer, therefore, proved to be extremely useful for

this measurement.

Ammonia reactions have been observed so far on both Si

0

2 fracture surfaces

and freshly deposited Si02 thin films Preliminary measurements of these

reactions on Si02 films stressed in tension by substrate bending show an apparent increase in N^

s peak size when compared with unstressed films

subjected to equivalent ammonia exposure.

In the next year we will seek quantitative confirmation of the abovereported effects and extend the fracture experiments to other gaseous

envi ronments.

561-90
This work is being carried out with the Fracture and Deformation Division.

Mechanical Properties of Thin Films

Studies of high temperature viscous deformation commonly known as creep

have been carried out for many years on bulk materials. Such studies

have not been made in thin films because of the experimental difficulties

involved. This is unfortunate because such information could lead to

improved protective coatings for metal parts used in high temperature

corrosive environments such as turbine blades. In addition, the effect

of thickness on creep in ceramic materials might improve the understanding

of bulk creep theories. For these reasons, the development of the

capability which will ultimately permit such measurements is necessary.

Central to being able to make such measurements is the ability to produce

well-defined thin ceramic films which can be separated from a portion of

their substrates over as large an area as possible. This is necessary

in order to permit the measurement of thin film mechanical properties

independent of the influence of that substrate.

To achieve this goal several approaches have been attempted. One involves

the deposition of the films on substrates which can be dissolved in an appropriate solvent. Examples of substrate-solvent combinations are glass/ five percent HF solution and sodium chloride/water. The inherent

problem with this technique is the difficulty to remove the released

films from the solvent without damage. This difficulty is also found

with thin film release agents used to cause the separation of the film

from its substrate.

Recently, we have been investigating the possibility of adapting halogen

transport of metal substrates as an alternative method of producing

unsupported films. This technique, which is normally used to refine

metals such as zirconium, involves the reaction of the metal at a lower

temperature to form a volatile iodide which dissociates at a filament

heated to a higher temperature. The zirconium is deposited on the

filament and the iodine released to react with more substrate material.

Such a technique does not involve the liquid state and may permit the

production of very thin unsupported films.

Finally, we have ordered a microhardness tester for use in a scanning

electron microscope. This tester will be used to explore the influence

of thin film microstructure on hardness.

Protective Films on Metals

The corrosion-hardness of many metals is the result of the formation of

protective oxide films. In spite of this technological importance the

exact structural character of such films is still poorly understood.

One theory suggests that the amorphous character of such films with

resulting lack of grain boundaries is the most important prerequisite

for corrosion protection. Earlier studies of films produced on iron

alloys with differing chromium contents showed a greater disorder in

passive films on metals with greater chromium concentrations. These

films were in turn the most protective of the underlying metal.

561-91
In preparation for studies of such passive films, we have been exploring

the use of the ESCA technique for the quantitative analysis of films

which have been produced on stainless steel using electrochemical passivation techniques. We have been carrying out qualitative analysis of the

ratio of iron to chromium as a function of film depth for several different

passivation conditions. The same films are being characterized using

ellipsometry to provide an i_n situ monitor of the passive film growth.

We expect that the results of the study will provide the necessary

background for a characterization of the structure of model passive

films produced by codeposition.

This work is being carried out in conjunction with the Corrosion Group.

561-92
CERAMIC PROCESSING AND DURABILITY SCIENCE

Task 12156

Task objectives focus on the development of theory, measurement methodology, standards, and data for producers and users of technical and bulk

ceramics. Polymers, glasses, and metals also are researched when specialized data and measurements techniques necessary for this task require

further refinement for application to ceramic systems. Emphasis is

placed on scientific aspects of the powder-process-structure-property

linkage that influence performance, reliability, and chemical /physical

durabi 1 i ty.

Research in this task includes significant collaboration with other

tasks in this Division and with other Divisions at NBS. Considerable

aid and expertise are given by the JCPDS Research Associateship (staff

of seven), one ceramic engineer guest worker from private industry, two

ceramic engineering co-op students, one postdoctoral appointee shared

with another task, and two guest workers from the U.S. Army. In addition,

R. Snyder, Alfred University; A. E. Evans, University of California/

Berkeley; R. Coble, Massachusetts Institute of Technology; and D. Readey,

Ohio State; rendered valuable consultation during this year. Partial

funding has been provided by various divisions in DOE, DOD, NASA (through

NBS subcontracts), Solar Users Association, U.S. Postal Service, and

several offices (OSRM, ORM, and ONDE) at NBS. Many new contacts are being

established for the purpose of assessing industrial needs in ceramics

research to help fashion the NBS role in future programs. The user commu- nity established via cooperative programs, professional societies and

committees, as well as via the dissemination of research results through

publications, SRM development, reports, etc., presently includes numerous

industrial, academic, and Government interests. Major research activities

are summarized by the following subtask areas:

1. measurements, standards, and processing applicable to ceramic

powders and particulates;

2. physical /chemical properties and durability of ceramics;

3. structural chemistry of materials at elevated pressure and

moderate temperature; and

4. evaluation and compilation of data.

Subtask 1 is concerned primarily with quantitative x-ray diffraction (XRD)

techniques, standards, and characterization data for powdered materials,

as well as for consolidated and densified or reacted products. This

research also serves as input for the Joint Committee for Powder Diffraction Standards (JCPDS) Research Associateship established at NBS

(Subtask 4). A major accomplishment this year has been the development

of x-ray line profile models which, together with application of digital

data collection, has improved the accuracy of x-ray powder data measurements by a factor of three to five.

Subtask 2 emphasis is on chemical/physical properties, durability, and

microstructural characterization of materials, including structural and

561-93
electronic ceramics, such as silicon carbide, zirconia-based ceramics,

and YCr03

. The latter has been shown to be an ideal model material for

the study of microflaws in ceramics by elasticity and small-angle neutron

scattering (SANS) measurements.

In Subtask 3, the structural chemistry of a wide variety of materials is

under investigation at elevated pressure using the diamond anvil pressure

cell (DAPC) facility and associated analytical techniques. A program

was initiated to investigate high pressure—moderate temperature phase

transitions for doped zirconia materials using- the DAPC. In addition,

the structures of amorphous materials were determined at elevated pressure

for the first time using radial distribution function (RDF) analysis and

the DAPC.

The Materials Performance Data Center and collaborative efforts with the

JCPDS are included in Subtask 4. NBS Monograph 25—Section 19 is scheduled

for publication this fall, and the handbook, Construction Materials for

Coal Conversion--Performance and Properties Data (600 to 700 pages) is now under review for publication in 1982.

Activities within each subtask are detailed below.

Ceramic Powders and Particulates--Measurements, Standards, and Processing

Subtask 1 of Task 12156

A. L. Dragoo, C. R. Hubbard, T. Negas, C. R. Robbins, and L. P. Domingues 1

1 Guest Worker from Trans-Tech, Inc.

SRMs for X-ray Diffraction (XRD) Analysis of Powders

Two instrument 26 calibration standards have been certified: SRM 640a

silicon powder and SRM 675 fluorophlogopite (FP) powder. The former is

a replacement for SRM 640 which was out of stock (> 850 units sold).

SRM 675 fluorophlogopite is intended as a low 26/large d-spacing standard.

In reflection geometry, only the 00£ lines are observed, and this simplifies the pattern for use as an internal standard. The d-spacing of the

001 line is 9.98104 (12) A (26 -v 8.8° for CuKa).

The certification methods employed were quite similar and involved use

of profile fitting to accurately determine peak position. The profile

function is a rational polynomial,

f(x) =

1

1 + A

X

X

2 + A

2

X4

J

where A-l and A2 must be positive or zero, and X = 0 at the peak. Asymmetry

was introduced by separately refining the parameters A x and A2 above and

below the peak. The CuKa 2 profile was assumed to be identical in shape

with the CuKe*! profile. The model contains sev#n parameters: 26 , Ia lf

o o h h "

Ia 2 , Aj , A2 , Aj_ , and A2 . The background was determined from data

points far removed from the peak and was not refined. The agreement

factor,

561-94
R = £ a . j ,2 1 1/2

i ^ calc obs ; £ W

for silicon profiles typically was 0.02 to 0.04.

y

The silicon lattice parameter was determined using silver and tungsten

internal standards. The fl uorophlogopite d(001) was determined using

silicon SRM 640a and tungsten internal standards. In both cases, a smooth polynomial was fit to the peak positions of the internal standard

lines. The rms deviation from the polynomial curve was usually 0.003°

29 or smaller. Least squares refinement of a(Si) or d^^ for FP gave

rms deviations of similar magnitude. Both SRMs were proven to be homogeneous through multiple measurements (> 20 in each case).

The application of digital data collection and profile refinement was a major accomplishment of this year. The accuracy in 20 measurement was demonstrated to be « 0.03° 20. This value is three to five times better

than the average error obtained by our strip chart recording/measuring

methods. The profile model employed is shown to be superior to modified

Lorentzian or Pearson VII functions. A paper on this function was given

at the March 1982 American Crystallographic Association (ACA) meeting and

has been submitted to the Journal of Applied Crystallography for publication.

Other on-going SRM-related projects include, (1) certification of res- pirable quartz (Si02 ) for relative intensities, reference intensity

ratios and percent amorphous content; and (2) research on development of

a submicron crystallite size SRM (see below). Dr. R. McKenzie, Analytical

Chemistry, is testing the quartz for homogeneous particle size distribution. Upon completion, the XRD measurements will be made. Development

of quantitative methods to determine glass or amorphous content is

expected to have significant impact on the analysis of Si C and Si 3 N 4 -based

structural ceramics and powders, as well as of more conventional bulk

refractories for metal processing. In conjunction with this work,

research on preparation of a cristobalite SRM will begin next year.

Preparation of Submicron Crystallite Powders

Research is being conducted to develop a submicron crystallite size SRM

to calibrate x-ray line-broadening measurements critical in establishing

baseline conditions for crystallite size, strain, and compositional

variation determinations. Methods of preparing magnesium oxide powders

consisting of submicron crystallites are being developed. Two methods

are under study: (1) production of MgO "smoke"; and (2) calcination of a magnesium containing precursor. An apparatus to burn magnesium metal and

to electrostatically collect the smoke was built and operated to produce

the particles. The smoke particles have a cubic morphology, so an independent determination of particle size can be made by electron

microscopy. The second method, using the decomposition of basic magnesium

carbonate, has been initiated. Conditions are being sought in this

latter method which will yield crystallites which can be geometrically

sized, as well as sized by x-ray line-broadening measurements.

561-95
Characterization of Particulates, Residues, and Corrosion Products

Physical and Chemical Characterization of Fossil Fuel Residues

This program relies heavily on the practical application of advanced XRD

techniques and mi crostructural /microchemical methods as developed by

this group and on other analytical methods available at NBS.

During the year, selection of methods of analysis, development of new methods and their application to test or simulated samples of ash residues were carried out for a DOE supported program. Methods and instrumentation

chosen include: scanning electron microscopy with energy dispersive x-ray

analysis (semi-quantitative); image analysis (quantitative); Auger methods

for surface analysis (semi-quantitative); and x-ray powder diffractometry

(both qualitative and quantitative). A spray dryer constructed to prepare

samples with a minimum of crystallite orientation for x-ray analysis was tested successfully, and used to prepare reference samples (fig. 1) for

quantitative analysis. Application of the computer programs of

C. R. Hubbard, NBS and R. Snyder, Alfred University (see below), for

quantitative XRD show the method is quite promising.

Samples of ash residues for analysis were received during April and May

of 1982, after an unanticipated delay. Analysis of the samples is now

in progress. In addition, nine ash samples were characterized at the

request of DOE as a measure of their sampling protocol.

Three collaborative studies of ash residues from emerging energy technologies were completed in FY82. They are:

a. "X-ray Analysis of Selected R-D-F and Coal Samples as a Function of

Temperature," with E. Domalski and R. Kelly, NBS Center for Thermodynamics and Molecular Science.

b. "Characterization of Ash Residues From a Refuse-Derived Fuel/Oil

Combustion Study," with F. Hasselriis, Combustion Equipment Associates, New York, NY.

c. "Characterization of Slag and Fouling Residues From Co-combustion

of Powdered Refuse-derived Fuel With Residual Oil and Comparison

With Coal and R-D-F Residues," with F. Hasselriis, Combustion Equipment

Associates, New York, NY.

Little information exists on the compound assemblages and their development in ash residues from emerging energy technologies, such as the

burning of refuse-derived-fuels (R-D-F), the co-firing of R-D-F and coal, or R-D-F and oil. The analyses by NBS gave a qualitative and semi-quantitative

picture of the crystalline phase development of four R-D-F, four coal, and

three slag and fouling samples from a utility boiler co-firing powdered

R-D-F with oil. X-ray diffraction traces of the powdered R-D-F showed the

destruction of crystalline cellulose due to thermal and chemical processing.

The relative amounts of glass, as distinguished from quartz and

other silicates, were significantly different in the various types of

R-D-F tested. This information helped to explain behavior of these fuels

561-96
in boilers, especially in those situations where firing had to be severely

restricted due to slagging conditions. As R-D-F ash temperatures are raised, shifts in chemical composition were noted in the analyses. Most

of the silicates became fluxed by the glass at the final temperatures

representing furnace conditions.

The sulfur and iron in the oil and R-D-F reacted with calcium in the

refuse, forming calcium and iron sulfates, thus reducing stack emissions

of sulfur oxides. Magnesium-rich compounds were predominant in the

fouling deposits formed during combustion of R-D-F, resulting from the MgO

additive to the oil.

Three feasibility studies related to the effects of acid rain have been

initiated for the National Park Service with J. Kruger, NBS Materials

Chemistry Division.

A preliminary study of the deterioration of selected Egyptian marble and

sandstone antiquities has been initiated, in part, at the request of the

Smithsonian Institution with W. P. Iverson, NBS Materials Chemistry

Division.

Computer Programs for XRD Analyses

The system of programs for determination of peak position and intensity

was discussed above. Plans are to add profile refinement algorithms

based on the programs developed for SRM certification this fall. Documentation of the package is also planned.

The quantitative analysis set of programs NBS*QUANT82 have been entirely

written in FORTRAN 77 by Dr. R. Snyder and C. R. Hubbard to enhance portability. Documentation has been written and example runs are being completed

Together, they will be published as an internal report along with the source code listings. Seimens Corp. intends to implement these programs

on their commercial diffractometer once publically available.

The program package implements the spiking, intensity ratio, and internal

standard method of XRD quantitative analysis. The latter method permits

line overlap and the inclusion of elemental chemistry data to the con- strained least squares phase analysis. The programs link directly with

our data collection program AUTO and permit relative intensity and

reference intensity ratio measurements. All programs permit use of

multiple lines, multiple mounting, and multiple runs to enable assessment

of the presence or absence of systematic errors. To assist the user in

interpretation of the results, expected counting statistic errors are propagated and rms deviations are calculated.

Use of the programs at NBS and at Alfred University has revealed weaknesses of methods commonly employed. In particular, microabsorption and

incorrect background assessment have been shown to be more serious

systematic errors than commonly held. These programs will be the basis

of data analysis for quantitative XRD SRMs, such as respirable quartz.

561-97
Ceramic Oxide Powders for Plasma Spray Coatings

In cooperation with a guest worker from private industry and with active

cooperation from D. H. Harris (APS Materials, Inc., Dayton, OH), flowable

powders of several high purity oxides were investigated to obtain dense,

adherent arc plasma spray (APS) coatings for molybdenum and mild steel

substrates. Present research has focused on powders of solid solutions,

(A1

i- x

^ rx^2^3’

^ = 0-20). Conventional pure alumina APS coatings

consist of metastable A1 2 0 3 variants (e.g., y-alumina) that undergo

large volume changes during transformation to the stable a-form at

elevated temperatures (> 1000 °C) after deposition. Pure chromia powders

yield poor APS deposition efficiency due to the high vapor pressure of

chrome oxide(s). Solid solution with alumina precludes this problem.

However, it has also been found that chromia influences the crystallization kinetics, such that APS coatings with high a-content (> 50 percent)

are deposited. Controlling mechanisms are not well understood at present.

Annealing at 1500 °C completes the transformation of the residual metastable phase(s) to a without loss of adhesion on Mo-substrates. Complete

transformation to a and post-deposition densi f ication to near 95 percent

of theoretical also were accomplished by hot isostatic pressing (HIP)

and 1100 °C, 30,000 psi.

G. W. Burns (Thermal Processes Division, NBS) is currently evaluating

these coatings on Mo-tubes used as thermocouple sheaths for temperature

measurements in gasification and molten iron and steel environments.

Preliminary tests have demonstrated that these coatings have superior

abrasion and corrosion resistance (to slag).

Materials have been processed by blending and reacting active powders of

appropriate components in the solid state at temperatures < 1200 °C.

After milling, these are spray dried to produce "soft" spherical agglomerates which, subsequently, are sintered, 1500 to 1550 °C. Dense,

spherical particulates ranging from 10 to 250 pm are produced.

Ceramic Green Compacts

The microstructure of densified ceramics controls their mechanical,

electrical, and chemical (e.g., corrosion resistance) properties.

Performance and reliability, therefore, are sensitive to microstructural

evolution and control which require two major aspects of processing

prior to sintering:

a. a reactive, deaggl omerated starting powder ideally of small size

(~ 0.1 to 5 pm), narrow size distribution, and controlled purity or dopant content, and

b. uniform, essentially defect-free (large pores, fissures, inclusions,

density gradients, etc.) green compacts consisting of deaggl omerated

particulates.

Defects, including agglomerates, that exist in green compacts generally

are amplified during sintering at elevated temperature (and pressure),

and these result in microstructural flaws that influence performance.

561-98
Normally, NDE methods (see, for example, J. Fagenbaum, Mechanical

Engineering, May 1982, p. 28, for an assessment of techniques) are used

to examine and, if necessary, to reject ceramics after sintering and

machining. Based on the importance of ceramic processing prior to

sintering (see above), identification of flaws by NDE at the green

compact stage would permit early rejection and superior product control.

Unfortunately, there has been very little research activity in this

field, although several potential techniques have been identified (see,

for example, A. G. Evans, Technical and Scientific Assessment of the

Reliability of Advanced Ceramics, Report to NBS, Divisions 561/562,

1982).

The NBS Office of Nondestructive Evaluation initiated a limited green

compact program for Divisions 561 and 562 during the past year. We have

focused on the processing and fabrication of green compacts containing

pores (> 10 pm) and pore cluster defects for examination by techniques

selected by Division 562 researchers. YCr03 -based compacts (see below)

also were processed for evaluation by small angle neutron scattering

(SANS). Deagglomerated alumina (A1 2 03 ) and spinel (MgAl 2 0 4 ) powders

were compacted by isostatic pressing (10,000 psi). Pore clusters were introduced via fugitive materials (e.g. , latex, starch) during compaction

followed by a mild "burn-out." Green compacts fabricated to shape for a specific NDE method will be developed in future work. These also will

include flaws, such as fissures (via fugitive filaments) and inclusions

(via spray dried, sintered particulates).

ZrTiOA -Based Dielectrics

In cooperation with Dr. A. McHale and Dr. R. S. Roth (Division 561),

processing of ZrTi04 -based ceramics is under investigation. These

ceramics have highly desirable dielectric properties, such as a high

(~ 38) and low dielectric loss. Furthermore, doping with Sn02 can vary and control the temperature coefficient (TC) of £' , which is ideal

for microwave integrated circuitry. Unfortunately, the material, including

Sn0 2 -doped variants, is difficult to density and foreign suppliers

utilize sintering aids, such as Ni, Zn-oxides. These normally degrade

the electrical properties of the homogeneous material.

A. McHale and R. S. Roth are investigating Zr02 -Ti0 2 -Sn02 reactions at

elevated temperature to elucidate structural chemistry and its relevance

to densifi cation and processing. This study is evaluating various

sources of Zr02 as a reactive starting powder for processing of ZrTi04. The key factor in past efforts to density ZrTi04 appears to be the

presence of Zr02 agglomerates in starting powders, and these are carried

through into the initial calcine with Ti02

. The agglomerates sinter

differentially to a microstructure consisting of dense and porous regions

with an overall low bulk density (fig. 2). Better control and characterization of the initial powders, therefore, are necessary.

561-99
Physical /Chemical Properties and Durability of Ceramics

Subtask 2 of Task 12156

S. Block, A. L. Dragoo, F. A. Mauer, R. G. Munro, T. Negas,

G. J. Piermarini, J. Waring, and L. P. Domingues 1

1 Guest Worker from Trans-Tech, Inc.

Structural Ceramics

Silicon Carbide and Boron Nitride

Research on silicon carbide is concerned with identifying polytypes and

impurity phases in silicon carbide ceramics and with determining the

product phases and their rates of formation in reactive gas environments.

The silicon carbide ceramics for study are candidate materials for

high-temperature heat exchangers. The reactive gas environments include

air (oxygen), S0 2 -containing N 2 and a simulated coal combustion gas.

When silicon carbide is heated in air, it is well known that a silicon

dioxide (cristobalite or tridymite) protective layer develops. After

the silicon carbide is exposed to coal combustion gas at high temperatures,

evidence has been found for a variety of detrimental reaction products.

As one part of these programs, a high-temperature x-ray diffraction

furnace is being developed to study the product phases at temperatures

up to 1500 °C. This furnace uses silicon carbide as the heater; either

the sample itself is made conducting and serves as the heater or a second piece of conducting silicon carbide serves as the heater and

sample holder. The furnace is designed (1) to minimize the volume of

material heated; (2) to use materials which are compatible with the

sample; and (3) to use improved ceramic thermal insulating materials.

This work is supported by the Department of Energy.

The electrical conductivity of boron nitride is being measured (with

H. P. R. Frederikse and W. R. Hosier) at temperatures approaching its

decomposition temperature at about 2500 °C to assess the high-temperature

performance of this material. Preliminary measurements to about 2200 °C

indicate an activation energy of about 2.6 eV (251 kJ/mol) for the

electrical conductivity. This work is supported by the Department of

Defense.

Mo-Si 1 icides .

In cooperation with the Harry Diamond Laboratories and G. W. Burns

(Thermal Processes Division, NBS), chemical reactions involving Mo-Si-N

were investigated at elevated temperature. Both groups are interested

in coating the interior of Mo thermocouple and/or fluidic pyrometer

sheaths with Mo-si 1 icides to protect the refractory metal against oxidation at ~ 1550 °C. We developed a technique based on the following

reaction:

561-100
3Mo + xSi

3 N4 * 3MoSix + 2xN

2

I .

Si 3 N 4 submicron powder is packed into a Mo sheath. The reaction proceeds

via diffusion of Si at temperatures at and above 1400 °C (in N 2 10% H 2 , 1 atm.) to produce a chemically graded coating consisting of MoSi

x phases

(fig. 3). Kinetics of the silicide process are under investigation and a manuscript describing the process and pertinent phase relations

is in preparation.

Microfissuring in YCrQ3 Ceramics

In cooperation with Dr. E. D. Case (Division 562), densified ceramics

based on YCr03 are under investigation to develop small-angle neutron

scattering techniques suitable for detection and analysis of

microfissures. Reactive powders of YCr03 were obtained by calcining

(-v 700 °C) a precursor prepared from Y 2 0 3 dissolved and reacted in

ammonium di chromate solution. Green compacts (cylinders) were fabricated

by isostatic pressing of spray dried powder at intervals between 2,000

and 10,000 psi. This permitted control of final bulk density after

sintering within the range 75 to > 95 percent of theoretical. Compacts

were sintered at 1750 °C (3 h) in forming gas (N 2 10% H 2 ) then cooled

(-V 100 °C/h) to RT. Rectangular slabs were cut from these ceramics for

elasticity and SANS measurements.

YCr03 was selected as a "model" material for these studies, as it apparently

undergoes a phase transition near ~ 1100 °C. This transition has not

been fully characterized, although weak signals were obtained by differential thermal analysis (DTA). However, the associated volume change must

be very small yet sufficient to induce microfissures. Thermal annealing

above 1100 °C introduces microcracks into specimens while anneals below

1100 °C heal the fissures. The process is reversible, as demonstrated by

elasticity measurements on as processed-anneal ed (< 1100 °C)-annealed

(< 1100 °C) materials. Microcracked ceramics typically yield a Young's

modulus < 140 GPa, while "healed" materials strengthen to values in excess

of 200 GPa. Furthermore, the microcrack number density (N) can be varied

by time versus temperature anneals without disturbing other microstructural

details, such as density or grain size. SANS measurements (E. D. Case)

correlate well with the elasticity data as changes in neutron scattering

intensity and angular spread of the neutron beam are observed. Analysis

o of the SANS data suggest microfissure cross-sections in the 150 to 200 A

range (see E. D. Case, this report).

Noncentral Forces in Ionic Compounds

Work was recently completed on a phenomenological description of both

the pairwise and multiple interactions in a complex of nearest neighbor

atoms and a central atom in a rock salt-type lattice. The mathematical

formulation which was developed identified many unrecognized possible

noncentral force interactions for this structure. The noncentral force

contributions to the lattice dynamics, elastic constants, and the force

constant for the homogeneous lattice polarization were identified.

561-101
Zirconia-Based Ceramics

Grain-Boundary Measurements

AC impedance and microstructural investigation of a "grain-boundary"

between two large grains of yttria-stabi 1 ized zirconia, which were

formed as part of a skull-melt crystal growth process, indicated that

'the boundaries in this material are gaps bridged by islands of yttriastabilized zirconia. Surface features on the grains give some clues as

to the last stages of crystal growth. These features suggest that a thin layer of the melt was trapped between the grains and that this

layer receded until it solidified into isolated islands of material

between the grains.

High Pressure Measurements

Zirconia and doped variations of zirconia show great promise as a useful

and reliable ceramic material, because of its exceptional mechanical

properties, its resistance to thermal corrosion, and its fast-ion electrical properties. The material also has the ability to be toughened by

controlled composition amd particle size of the tetragonal and cubic

phases. Crack propagation can be halted by the martensitic tetragonal

monoclinic transition or by second phase dispersions in monolithic

ceramics or composites.

We have studied the cubic phase of Zr02 /8 mol % Y2 0 3 , one of several

samples supplied by T. Negas, by x-ray diffraction to 30 GPa and by

optical polarizing microscopy to 300 °C and 15 GPa to investigate its

phase behavior and measure its compressibility, both being useful for

understanding the HIPing process. Over the pressure and temperature

ranges studied, no phase transitions in Zr02 /8 mol % Y2 03 were observed.

The pressure dependence of volume for the material is shown in figure 4.

The calculated bulk modulus for this material is 331 ± 2 GPa, and its

pressure derivative is 19.8 ± 0.4.

Ceramic/Glass Emission Standards

In cooperation with D. J. Cronin (Glass Group, Division 561), fluorescent

and phosphorescent ceramic/glass standards are under investigation for

the U.S. Postal Service. The USPS requires several sets of emission

standards to calibrate their primary instruments for detection of emission

levels from stamped mail which is sorted and cancelled by their high

speed, in-field machinery. This new program has focused on processing

of glass/ceramic composites having emission characteristics within the

red and green phosphorescent and the red fluorescent range, as well as zero emission materials. Sintered borosilicate glass powders doped with

Eu3+ and with Tb 3+ and sintered Y 2 0 3 :Eu plus borosilicate glass constitute

candidate materials. Zero-emission candidate materials include Mn,

Zn-ferrite spinel and Y 5 A1 3 0 12 (garnet) ceramics.

Materials for Hot Phosphoric Acid Fuel Cells

This is a new program established by the DOE to investigate materials

and corrosion processes associated with first generation, phosphoric

561-102
acid fuel cells. Normal construction materials, such as copper, in the

cooling segments of fuel cell stacks are subjected to corrosion by phosphoric acid (> 150 °C) electrolyte. In cooperation with D. S. Lashmore

and J. Kruger, several candidate protective ceramic oxide and metallic

coatings on copper will be fabricated and evaluated for resistance to

acid corrosion. Ceramic and metal alloy expertise is provided to DOE

for their subcontract engineering design work with Englehardt and United

Technologies researchers. Failure analysis of a metal alloy reformer

w/ithin a 4.5 megawatt fuel cell system at Consolidated Edison, NY, was recently performed.

Structural Chemistry

Subtask 3 of Task 12156

S. Block, F. A. Mauer, R. G. Munro, and G. J. Piermarini

High Pressure Studies of Crystalline, Semi crystalline, and Amorphous

Materials

Zirconium Oxide

(See Subtask 2, Zirconia-Based Ceramics).

Nickel Base Superalloy

In cooperation with Watertown Arsenal, we have measured the compressibility

and determined the phase behavior of a nickel base alloy, MAR-M200, by

x-ray diffraction to 13.7 GPa. Watertown Arsenal has discovered that

MAR-M200, a high strength alloy which has important military applications,

loses an appreciable amount of shear strength when shock-loaded beyond

2.8 GPa, its Hugoniot Elastic Limit. MAR-M200 is assumed to be an ideal

mixture of two face centered cubic phases, y and y

1 , which have large

differences in compressibilities. Thus, when the alloy is subjected to a large stress, as in the case of the firing of a large caliber gun, the

differences in the compressibilities of the two phases and/or the possibility of a y-y' transformation may be the mechanism for the breakdown in

the shear strength. Our x-ray results show no indication of a phase transition and no evidence of line-splitting to indicate a compressibility

difference effect over the pressure range studied.

Indium Bismuth Intermetallic Compounds

In collaboration with J. Jornada of the Institute of Physics, Brazil, an x-ray diffraction study of the high pressure phase transition in the

intermetallic compound, In2 Bi, was carried out using the diamond anvil

pressure cell and the energy dispersive technique. The 17 kbar reversible

transition has been detected previously by resistivity and superconducting

critical temperature (Tc) measurements. These measurements suggest that

the transition involves a decomposition into In 5 Bi 3 and In-rich phases.

However, recent Nuclear Quadrupole Interaction (NQI) measurements by

Jornada on the In 2 Bi transition can be interpreted as a change to In 5 Bi 3

structure with 3/48 of the In atoms occupying random positions in the Bi

sublattice instead of the proposed decomposition suggested earlier. Our

x-ray measurements confirm that the high pressure phase is, indeed, the

561-103
I

n

s B

i

3 structure. The fact that there was no indication of the presence

of any other phase, suggests that the random structure is probably

correct.

Polymers

In collaboration with the Polymer Science and Standards Division, the

crystal structures of the high pressure forms of polytetraf 1 uoroethylene

(PTFE) and a random copolymer of hexaf 1 uoropropylene and tetrafl uoro- ethylene (FEP) were determined. An energy dispersive x-ray diffraction

method was employed in conjuction with a diamond anvil high pressure

cell. Both high pressure forms were found to consist of planar zig-zag

chains, but with unexpected differences in the interchain packing. One

possible explanation to account for this difference is a twist in the

chain of the FEP copolymer to accommodate the bulk CF 3 side group. The

averaged lateral chain packing in the FEP copolymer becomes hexagonal,

thus differing from the orthorhombic packing of the PTFE homopolymer

high pressure phase. Compression of the high pressure PTFE phase was measured to four GPa for the first time by an x-ray diffraction method.

Amorphous and Glassy Materials

There is a class of materials, often called metallic glasses, that is

becoming of great interest to industrial and engineering applications.

Present indications are that these materials are potentially among the

strongest and most corrosion-resistant metals known.

In general, the structure of an amorphous or glassy material can be

expressed in terms of radial distribution function. As a result of work

initiated in our laboratory at the request of Watervliet Arsenal, this

method has been successfully applied to the study of materials at high

pressure in a diamond anvil pressure cell. In particular, energy dispersive x-ray diffraction has been used to investigate the structure of

amorphous Fe-W (56 wt. % W). The sample was supplied by Watervliet

Arsenal. For comparison, the RDF was determined at low pressure (near

one atmosphere) in the DAPC and also outside the DAPC at one atmosphere.

Figure 5 shows the comparison of the results. Measurements made to

10.5 GPa indicated an approximately linear compression, as shown in

figure 6 , with an isothermal bulk modulus of 170 GPa (J. Appl. Phys.

,

Sept. 1982).

Presently, in collaboration with D. S. Lashmore of the Electrodeposition

Group, this new capability is being applied to amorphous Ni-P which is

suspected of having two different amorphous phases, resulting from two

different methods of production. This project will attempt to discern a difference between the two samples and then investigate the possibility

of a transition between the two under the influence of pressure.

High Energy Materials RDX

In cooperation with Picatinny Arsenal and the Naval Surface Weapons

Center, we are developing methods which permit us to measure and identify

decomposition rates and processes in l,3,5-trinitrohexahydro-l,3,5-

triazine (RDX) as a function of temperature and pressure. Nitramine

561-104
propellants containing RDX as a binder show complicated ballistic behavior

which can effect performance reliability. An anomaly in the burning

rate of RDX is observed in the region of 0.3 kbar and is thought to be

the result of a change in the mechanism of decomposition. At low pressures,

decomposition proceeds predominantly by C-N bond rupture, while at

pressures greater than 0.3 kbar, decomposition involves the breaking of

N-N type bonds. Depending upon which mechanism is followed, the products

of decomposition can be chemically very different. Since large guns

operate in the 3 kbar range, to better understand RDX's complex ballistic

behavior, it is important to study the effect of pressure and temperature

on the thermal decomposition and rate of decomposition of the material.

Our initial approach involved Raman scattering measurements of RDX as a function of temperature and pressure using a diamond anvil pressure cell

with a micro-Raman laser technique. The pressure and temperature dependencies of the internal (molecular) and external (lattice) vibrational

modes of RDX were measured up to 150 kbar and 175 °C. However, the

intensity of the scattering diminished relative to background levels as the melting point was approached, and no scattering from the decomposition

products could be measured. Gruneisen parameters for RDX were calculated.

Solid residues of decomposed RDX obtained for several different conditions

of pressure and temperature were examined by F. E. Brinckman and W. R. Blair

(Materials Chemistry Division) using High Precision Liquid Chromatography.

Preliminary results indicate that the chemical species in the residues

differ and are a function of the decomposition pressure and temperature

conditions. The identity of the products is not determined yet. More

work in this area is in progress. An infrared absorption method which

makes use of a Digital Fourier Transform Spectrometer is being developed

and will be used to identify the decomposition processes in RDX.

Cadmium Sulfide

The work on the synthesis and high pressure electrical studies of Cl

doped CdS sponsored by DOD continued. We investigated several methods

of adding Cl to CdS precipitated from CdCl 2 solution by H 2 S or Na 2 S. The samples were analyzed by the Center for Analytical Chemistry and

sent to Watervliet Arsenal for determination of electrical properties.

Calculations of Cd-Cl complexes with a program provided by

Dr. F. E. Brinckman and modified by Dr. R. G. Munro, guided the synthetic

work.

Isothermal Equations of State

It is useful to express the results of high pressure structural studies

in terms of isothermal equations of state. Numerous such equations have

been proposed in the literature, with each different equation representing

different assumptions about the physical system. Usually, it is not

easy to determine a priori which of these models is most appropriate for

a given material. Least squares fits of these models to a given set of

data can yield comparably good fits, while giving significantly different

values for the thermodynamic parameters, such as the isothermal bulk

modulus. Consequently, it is advisable to consider all of these equations

in detail before quoting any one of them as the equation of state.

561-105
For that purpose, a FORTRAN code has been developed to analyze lattice

parameter and volume data in terms of nine possible isothermal equations

of state. A second procedure involving a piecewise regression analysis

has also been developed. Applications have already been made to H 2 0-VII

and D 2 0-VII (J. Appl. Phys. , Sept. 1982), and presently Zr02 is being

studied. Figure 7 shows an investigation of the bulk modulus of H 2 0-VII

and D 2 0-VII using these routines.

Pressure Measurements at High Temperature

Efforts to develop high temperature capability of the DAPC for application

to ceramic materials are currently in progress. One aspect of this work

involves improving the accuracy of pressure measurements at high temperature. Measurement of the shift of the ruby R1-R2 fluorescence lines

provides the principal means for determining the pressure in a DAPC.

The wavelengths and widths of these lines are strongly affected by

temperature; and at high temperatures, R1 and R2 overlap significantly.

At low temperatures, an additive correction term is adequate to account

for the contribution of temperature to the shift of the R-lines, but at

high temperatures, the overlap of R1 and R2 introduces larger uncertainties. Consequently, a detailed modeling of the full R1-R2 lineshape, as

a function of temperature and hydrostatic pressure, is under study.

While several models are suitable, a combined Lorentzian-Gaussian model

appears to have several desirable features: speed, accuracy, and adaptability. An example of the compatibility of the model with the observed

R1-R2 intensity profile is shown in figure 8. The data points in the

figure are connected to form the slightly jagged line, while the model

is the smooth dashed line.

Thermal Diffusion in the DAPC

For experiments performed at high temperatures, it is essential to know

how much time would be required to establish thermal equilibrium in a DAPC following a change in temperature. It would also be valuable to

know the temperature distribution profiles in the DAPC during the transient

heating and cooling periods. These could help identify "hot spots" and

"cold spots." For certain work, it would also be useful to know when a temperature variation or gradient would have a real-time duration of a length sufficient for experimental monitoring. To provide estimates for

these quantities, a FORTRAN program is being developed specifically for

the geometry of the DAPC and its multi -material composition.

Synchrotron Studies

A new method for obtaining powder diffraction patterns from secondary

phases in powders, compacts, and microstructures with improved resolution

in the diamond anvil pressure cell is being developed in collaboration

with scientists at the Cornell High Energy Synchrotron Source (CHESS).

The method retains the fixed-angle feature of the energy dispersive

method which makes it adaptable for use with environmental chambers.

Wavelength scanning of the incident radiation for spectral analysis of

the diffracted beam is used. Since the energy resolution of a channel

cut silicon monochromator is at least an order of magnitude better than

561-106
that of a solid state detector system, it should be possible to obtain a substantial improvement in the resolution of diffraction patterns if the

divergence of the slit system is kept below about 10“3 radians. At the same time, by using a detector with an annular slit to intercept all of

the radiation diffracted at a fixed angle of 28 = 12°, it is possible to

increase the efficiency by a factor of twenty and to reduce the graininess

that is typical of patterns from microscopic specimens.

The feasibility of the new method was demonstrated in experiments conducted

at CHESS in May of 1981. Count rates as high as 8000 counts per second

for the 101 reflection of a-quartz were obtained, and it was demonstrated

that the intensity of the synchrotron radiation was at least 2 x 10 4

times greater than that of the Bremstrahl ung from a 12 kW rotating anode

source. Patterns were also successfully recorded from samples in the

diamond anvil cell. Due to limitations of the monochromator used for

the 1981 experiments, we were unable to record any diffraction lines

that occurred at energies above 32 keV. Also, because we used an existing

detector that severely limited the diameter of the annular slit, we were

not able to demonstrate improved resolution.

A greatly improved wavelength scanning microdiffractometer was designed

and built at NBS and tested at CHESS in May 1982. Using the A2 line,

which has an unusually large monochromator crystal, we were able to

extend the range of powder patterns to 50 keV, which, for 26 = 12°,

o corresponds to a d-spacing of 1.18 A. The resolution was 0.042 keV at

17.7 keV, or 0.24 percent. This is nearly a ten- fold improvement over

the resolution obtained in the earlier experiments at CHESS and about

four times better than the limit for systems using a solid state detector.

Unfortunately, we were unable to obtain a satisfactory pattern from

samples in the diamond anvil cell either at high resolution or with the

slit widened to approximate the resolution (and count rate) characteristic

of the earlier experiment at CHESS. At this time, we are endeavoring to

determine why we cannot reproduce our earlier results. Indications are that the difficulty is due to some flaw in the alignment procedure. In

particular, we suspect that the expression built into our software to

track changes in the height of the beam during the energy scan may not

have been adequate. We are particularly anxious to overcome this difficulty because plans are underway for an effective six-fold increase in

beam intensity at CHESS. This would greatly enhance the capability of our method of obtaining diffraction data, whereas the energy dispersive

method has already reached count rate saturation and cannot benefit.

Evaluated Data--Production and Compilation

Subtask 4 of Task 12156

C. R. Hubbard, H. M. Ondik, and A. Perloff

Standard Reference XRD Patterns

The JCPDS —International Centre for Diffraction Data's Research Associateship continues to produce highly accurate standard reference powder

patterns in collaboration with C. R. Hubbard. NBS Monograph 25, Section 19

will be published in September/October and will contain approximately 50

experimental and one calculated pattern. Over two-thirds of the patterns

are designated as "common phases."

561-107
During this year, the transition from strip chart recording and measure- ment to digital data collection and processing has been made. An extensive set of programs has been developed by Dr. N. Pyrros of the JCPDS,

in collaboration with Dr. C. R. Hubbard. Program capabilities include

second derivative background and peak finding algorithms, interactive

and hard copy plotting (fig. 9), internal standard calibration, and

interactive PEAKS file editing. These programs are all coupled through

the PEAKS file, which contains the results of peak findings. Data

files for input to indexing and lattice parameter least-squares refinement

programs are also generated. To evaluate and improve the digital methods, over one-half of the patterns of Section 19 were measured and processed

both manually and digitally and the results compared. In nearly every

case, the accuracy of the digital methods equalled or exceeded the

accuracy of the more traditional manual methods. The programs will be

the subject of a presentation at the Denver X-ray Conference, August 1982.

The Research Associateship continues to be involved in other activities

of the JCPDS. Marlene Morris chairs the Common Phases Task Group which

published a revised and updated Common Phases Search Manual in 1982.

Use of this search manual speeds phase identification when one or more

of the phases of a mixture are in this subfile. All computer based

search/match programs also permit searching of this file prior to searching

the entire powder diffraction file (PDF). Mrs. Morris is now collaborating

with the Forensic Subcommittee to put together a forensic subfile of the

PDF. E. Evans and C. R. Hubbard have collaborated with the Least Squares

Data Set Task Group to put together a comprehensive set of test data for

lattice parameter least-squares. This effort indicates that our leastsquares refinement program is operating successfully. Errors in commercial

and other programs were uncovered.

Critical Reevaluation of the PDF

The PDF is used in thousands of laboratories for phase identification.

The file consists of over 38,000 patterns collected over a period of

35 years. C. R. Hubbard, as Data Base Subcommittee Chairman, has been

actively involved in the JCPDS five-year project to critically reevaluate

the entire PDF and to build a master magnetic data base. NBS activity

has been coordinated with the Crystal Data project. Both data centers

use the program NBS*AIDS80 for data evaluation and data bank creation.

By June 1982, Dr. W. Wong-ng on the JCPDS and C. R. Hubbard have processed

through NBS*AIDS80 over 10,000 patterns. Another 10,000 will likely be

processed by October 1982.

To assist in this project, the JCPDS hired a computer consultant for the summer to add further evaluation routines (e.g., name-formula checking

and quality mark assignment) and to process the large number of data at

NBS. Data inconsistencies and errors are flagged. When possible, the

magnetic data bank will be corrected. If irresolvable errors are found,

the phase becomes a candidate for experimental work at NBS or elsewhere.

Materials and Components for Fossil Energy Applications

The Fossil Energy Materials and Components Data System consists of two

Data Centers operating cooperatively to provide a central source of

561-108
materials and components performance and properties data. One element

of the system is the Materials Properties Data Center, which is responsible

for compiling information on construction materials for coal conversion

use and includes data for MHD power generation as time allows. This

Center is staffed by personnel from the Materials Chemistry Division

(Ondik and Perloff). The major source of data is the Data Center's

library of DOE materials research contractor's reports. There are about

50 DOE-funded projects generating materials properties and performance

data for coal conversion and utilization. About a dozen of these projects

have generated magnetohydrodynamics (MHD) materials data. As time

allows, other information sources are sought to expend the data base.

Computer storage of the materials properties data base and access to it

is handled by a commercial data base management system.

The other segment of the information system is the Materials and Components Plant Performance Data Center, staffed by B. W. Christ of the

Fracture and Deformation Division (562). The source of the information

consists of reports of materials and component failures submitted to DOE

on a voluntary basis by the various coal conversion plants. The information is abstracted and entered into computer storage under a system

allowing high speed retrieval with a variety of search schemes. A major

use to which the file has been put by requestors of information has been

an attempt to correlate operating experience so that trends will be

observed indicating primary causes of plant failures for the guidance of

designers and operators of coal conversion plants.

The existing computer file of the Materials and Components Plant Perfor- mance Data Base contains some 500 reported failures. Although few pilot

plants are now operating, resulting in no increase of the data file,

there is continuing interest on the part of the user community. Since

the data base was started in 1976, hundreds of requests have been answered

by distributing over 17,000 computer abstracts and over 800 complete

copies of operating event or failure reports. The Center has also given

out some 40 copies of reports consisting of sets of abstracts on specific

topics, such as corrosion, or for specific materials. Several statistical

tables can be prepared by computer from the data base information and over 200 copies of these tables have been distributed.

The major product of the work of the two Data Centers is a book, Construction Materials for Coal Conversion--Performance and Properties Data, an NBS Special Publication SP-642. The book is published as sets of pages,

punched with holes to fit standard 3-ring looseleaf notebooks, a format

used by a number of other data books. Increasing and revising the data

can be done readily on a regular basis. A special binder for the book is

available for the looseleaf pages. The publication comprises 600 to 700

pages of data and discussion. This first issue of pages focuses on plant materials data for coal gasification, that form of coal conversion

for which there is the largest body of materials data available. The

book contains information gained in practical plant experience, as well

as the results of materials research and testing programs. It deals

with the information in the context of nine separate component areas of

the coal gasification plant. The data applicable for a component area

is summarized and discussed under that heading. The detailed results of

the research and testing programs are included in a separate section

561-109
which is divided into four sections covering the major performance and

properties data investigated in these programs. These four sections are headed:

(1) Corrosion Effects, Chemical Reactions, and Phase Changes;

(2) Erosion, Erosion/Corrosion, and Abrasion Effects;

(3) Mechanical Properties Testing; and

(4) Physical Properties Testing.

Each of these sections is divided into subsections for alloys, ceramic

refractories, and where such data exist, for coatings. A detailed index

to the book lists the materials covered grouped by type. For metals,

typical categories are stainless steels, cobalt-based alloys, carbon

steel, etc. For refractories, the groupings first list the industrial

categories--bricks , castables, etc. --and then the composition. For each

material, the various properties are given for which data appear in the

book, followed by the reference to the section and page of the book. It

is possible to find testing and properties data for specific materials

using this index.

561-110
Figure

1

Spray

dried,

reference,

XRD

powders

as

spherical,

homogeneous,

soft

agglomerates

(<

50

pm).
Figure 2 ZrTi04 ceramic illustrating differential sintering of partly

agglomerated, compacted powder.

561-112
Figure 3 Micrograph illustrating molybdenum silicide, graded coating

(upper layer, <0.1 mm) on the interior surface of a Mo metal

tube.

l

561-113
ZrO

e y

‘srnnioA

i

. 561-114

5.0 :

:

10.0 |

15.0

20.0

25.0

30.0

i

•

•
DIFFERENTIAL

RDF

FE-W AMORPHOUS ALLOY

0.0 2.0 4.0 6.0 6.0 10.0 12.0 14.0 16.0 18.0 20.0

RADIAL DISTANCE(ANGSTROMS)

Figure 5 RDF analysis of Fe-W amorphous alloy, comparing results obtained

from the diamond anvil pressure cell (DAPC) and from outside the

DAPC (dashed line).

561-115
PRESSURE,

GPa

RELATIVE POSITION, R/R(0)

0.97 0.98 0.99 1.00

o

Figure 6 Change in percent peak positions of amorphous Fe-W alloy with

pressure.

561-116
BULK

MODULUS,

GPa

200

150

100

50

0

Figure 7

10 20 30

PRESSURE, GPa

Bulk modulus of H2 0 VII and D 2 0 VII as a function of pressure

as determined by two methods.

561-117
-RUBY—

R1~R2

LINES

MODEl561-118
0PO26D

:

SRAL04

561-119

Figure

9

Example

of

hard

copy

output

including

digital

data

collection

and

computer

processing

for

standard

reference

x-ray

diffraction

patterns.

RECYCLED OIL PROGRAM—Division 561 Activities

The Tribochemistry Group of the Materials Chemistry Division has the

special assignment of providing a technical base of data and measurement

methodology to support the Bureau's Recycled Oil Program (ROP). This

program is mandated by Congress, under the Energy Policy and Conservation

Act, to provide test procedures which can be used to establish the

substantial equivalency of virgin and recycled oil products. At the

same time, the Group provides, within the Center for Materials Science,

major scientific and technical competences in chemical stability of

complex organic mixtures at metal surfaces, chemical reaction kinetics

in complex condensed-phase systems, friction and wear of materials,

tribology, and detailed chemical characterization of complex organic

molecules such as lubricants and fuels.

Tribochemistry

Subtask of Recycled Oil Program

S. M. Hsu, J. J. Comeford, A. L. Cummings, I. Bartky, P. T. Pei,

S. J. Weeks, R. S. Gates, D. E. Mathews, C. S. Ku, D. B. Clark,

Y. C. Wu, and K. L. Jewett

Current technical effort is directed toward development of measurement

methods for lubricating oil performance and consistency, and understanding

of the mechanisms of lubricant degradation and its effects on friction

and wear.

The most important requirement for assuring the quality of re-refined

motor oil is development of a set of test procedures capable of monitoring

the quality, consistency, and additive response of the lubricating

basestocks between periodic engine sequence test qualifications.

At NBS the program is underway in this Group to evaluate the chemical

and physical test procedures used on lubricating oil basestocks, as well

as to perform research and development on bench-scale performance tests

to establish basestock additive response.

In the past year, significant progress has been made in achieving the

goals of the recycled oil program. Laboratory evaluation of physical

and chemical property test procedures have been completed. The NBS/ASTM

basestock consistency study, the most extensive study of its kind, has

been completed and the data analysis by statistical methods will be

completed this year.

Several laboratory bench tests were developed to simulate full-scale

engine dynamometer tests on oxidation stability and wear characteristics

of lubricants. A catalyst package consisting of an oxidized, nitrated

high boiling fuel fraction and a mixture of metal naphthanates was developed to simulate the chemistry in an operating engine. The concentration and relative proportions of the catalytic components were shown

to be critical. Addition of the optimized catalyst package enables

several NBS developed oxidation tests to correlate with ASTM engine

sequence HID test results. A plan was developed to produce the catalyst

package as a reference material for industry.

561-121
Two cooperative studies with industry were conducted in FY82. The NBS/ASTM

basestock consistency program was successfully concluded in May 1982.

Monthly production samples of lubricating base oils were received from

ten refineries (6 re-refined, 4 virgin base oils). Fourteen industrial

and Government laboratories participated in analyzing these base oils

for consistency and performance. The results of this study are being

analyzed by statistical methods. This invaluable database will set a universal criterion for lubricating base oil production quality control

worldwide for decades to come. In addition, this database fills a vacuum in addressing batch-to-batch quality control for re-refined base

oils, hence fulfilling a key objective in the Congressional mandate of

substantial equivalency between re-refined and virgin oil products.

A cooperative study with eleven companies was initiated in April 1982 to

study the effects of base oil composition on oxidation stability. Over

100 base oils from ten crude sources were supplied by the companies.

Using a NBS developed thin-film oxygen uptake test, statistically significant correlations linking compositional parameters to oxidation stability

were established. Interestingly, re-refined base oils from various

processes constitute a distinct subset of the base oils. The addition

or subtraction of re-refined base oils from the total base oil set did

not affect the degree or the nature of the correlations.

In research on the mechanisms of lubricant degradation a gel permeation

chromatography-graphite furnace atomic absorption (GPC-GFAA) apparatus

was built to study the role of organometal 1 ic reactions in wear contacts.

Organic iron compounds formed as a result of wear were found to be

associated mainly with high molecular weight oxidized hydrocarbon structures (1000 to 100,000 MW). Static oxidation tests also exhibited

formation of such organometal 1 ic species at high temperatures (200 to

250 °C). A high pressure chemiluminescence apparatus was designed and

built to study the kinetics of this interfacial reaction. Fundamental

understanding of these reaction mechanisms may hold the key to various

technologically significant processes such as corrosion, oxidation,

friction, and wear.

Significant advances were also made in the area of separation science of

complex organic mixtures. A novel separation method was developed using

a neutral activated alumina column and selected solvent systems to

separate the naturally occurring polar molecules in fuels and lubricating

base oils into their molecular compound classes. Currently a prep HPLC

technique is being developed to produce quantities of these molecular

specific fractions for performance and stability characterization.

There are three main project areas: Hydrocarbon Separation; Oxidation

Stability; and Friction and Wear.

Hydrocarbon Separation

Lubricating oil basestocks are complex mixtures of several types of

hydrocarbons such as saturates, aromatics, and polars. The composition,

especially with regard to the polar type hydrocarbons, is a critical

determinant of lubricant performance. The polars are a minor group

composed of the most active molecular species in a lubricating base oil.

561-122
The structural characteristics of these active species will provide

information with regard to its effects on basestock performance.

A novel separation scheme for complex petroleum mixtures such as lubricating base oils has been developed. This new method provides insight and

basic information linking molecular structures to oxidation stability

and wear. The first step of the separation scheme is to separate the

oil into three major fractions: saturates; aromatics; and polars using

an NBS developed preparative HPLC procedure. The polar group has been

previously determined to have a significant effect on oxidation stability

and wear characteristics of the lubricating base oil. A new separation

scheme was developed to separate the polar fraction into various molecular

compound classes. Three major compound classes were identified: polynuclear aromatic compounds; nitrogen containing basic compounds; and

oxygenated polar compounds such as phenols and esters. Each subfraction

is studied for performance. The results suggest that the polynuclear

aromatic compounds have little effect on oxidation stability but have a higher wear protection. The nitrogen containing compounds have strong

anti -oxidant functions, but offer little wear protection. The oxygenated

compounds such as esters and phenols have little anti -oxidation property

and also offer low wear protection.

The complete separation procedure consists of three steps. The basestock

is first eluted on a clay column into saturate/aromatic and polar fractions.

The saturate/aromatic fraction is further separated on a dual packed

silica gel /alumina column into saturate and aromatic fractions. The

last step is the separation of the polar fraction into its subfractions

on a neutral alumina column. The mass balance of the separation is good

and the fractions produced are ready for performance evaluation.

Spectroscopic methods such as IR, UV, and high resolution mass spectrometry

as well as gel permeation chromatography have been applied to elucidate

structural characteristics.

Oxidation Stability

Significantly increased activities in this area in the past year result

in several major accomplishments: development of a thin-film oxygen

uptake test (TFOUT); development of a differential scanning calorimetry

(DSC) oxidation test; development of high pressure DSC instrumentation;

degradation mechanism study; the establishment of an NBS/industry cooperative study on base oil composition effects on oxidation stability; and

microoxidation and chemiluminescence studies of oxidation.

A New Oxygen Uptake Method

Lubricating oils currently are qualified through actual engine testing.

The Tribochemistry Group developed a thin-film, oxygen absorption test

that correlates with the ASTM engine sequence test HID on oxidation

stability, one of the four engine tests that an oil must pass to satisfy

automakers' warranty requirements.

The new test provides industry with a valuable research tool for examining

various new additive chemistries as well as a valuable screening tool

561-123
for new formulations. It is also a key development in meeting the NBS

Recycled Oil Program objective. The test provides an economic means to assess the quality consistency of re-refined oils.

The new test incorporates a conventional rotating thin-film oxygen

absorption test which simulates the key reaction zone in the high temperature piston ring area. Using a conventional rotary bomb oxidation

tester (RBOT) which is commonly available in industry, we modified the

hardware to ensure a uniform thin-film oxidation condition to avoid mass transfer effects. Initial results suggested that a catalyst system was needed to simulate the key chemical reactions in an engine. Based on used oil analyses, a combination of lead, iron, copper, manganese, and

tin (82, 6, 4, 4, 4 percent respectively) was adopted as a metal catalyst.

In addition, research reported by Southwest Research Institute suggested

that oxidized fuel components in the blowby gases (combustion gases in

the engine combustion chamber leaking through the piston rings) contributed

significantly to oil degradation. The final combination of 3 percent

metal catalyst and 3 percent oxidized/neutralized fuel components produced

results which correlated with the ASTM engine sequence HID test data.

About 20 additional commercial oils were tested and the results indicate

that they fell within the expected range of quality.

Differential Scanning Calorimetry (DSC) Oxidation Test

A new differential scanning calorimetry test has been developed. Results

of the test also correlate with the ASTM Sequence HID engine test. The

DSC test measures antioxidant degradation time in a high pressure oxygen

atmosphere (3.6 MPa) in the presence of oxidized nitrated fuel and metal

catalysts. The fuel and metal catalysts described above were used to

simulate the chemical environment of an operating engine.

The HID engine test simulates high temperature, high load highway

operating conditions and measures oil viscosity increase, deposit formation, and wear. The oil viscosity increase is related to the degree of

oxidation of the oil, which is controlled by antioxidant additives in

the oil. Viscosity increase is very slow until antioxidants are depleted,

whereupon the viscosity increases very rapidly. Thus, the time to a critical viscosity increase (375 percent in the HID test) can be related

to the antioxidant lifetime.

The DSC test provides an oxidation induction time which reflects antioxidant depletion time. The observed induction time and the precision with

which it can be determined are dependent on the temperature and pressure

at which the test is performed. The observed induction time decreases

with increasing temperature and oxygen pressure, but precision improves.

The optimum conditions for correlation with HID engine tests were

175 °C and 3.62 MPa oxygen.

DSC measures the rate of heat evolution or consumption by thermal events

occurring in a sample. Oxidative degradation of an oil proceeds by a complex free-radical chain-reaction mechanism which includes some very

energetic exothermic steps. Antioxidants provide rapid, low-energy

alternative reaction paths which produce relatively little heat. After

the antioxidant is depleted, autocatalytic chain-reactions proceed and

561-124
the rate of exothermic oxidation rapidly increases with time. In a DSC

test, the DSC signal is essentially constant until antioxidant is consumed,

then rises sharply as autocatalytic degradation accelerates. The antioxidant depletion point is marked by the sharp rise in the DSC signal.

Correlation of DSC results with engine tests was demonstrated by DSC

tests of ASTM HID reference oils of known engine performance. DSC

induction times correspond to the HID time to 375 percent viscosity

increase.

High Pressure Power-Compensation DSC Instrumentation

A high pressure modification of a commercial power-compensation DSC has

been developed. In order to effectively study thermal oxidation of

lubricants and fuels by DSC, pressures up to 4.5 MPa were needed. High

pressure heat-flux DSC has been commercially available for several

years, but high pressure power-compensation DSC has not. Attempts by

manufacturers and users of power-compensation DSC to operate at pressures

greater than 2 MPa have produced severe instability in the DSC signal.

The new instrumentation can operate up to 5 MPa.

Differential scanning calorimetry detects thermal events (reactions,

phase transitions, etc.) which occur in a sample by comparing the sample

to a stable reference. Power-compensation DSC measures the difference

in power required to maintain the sample at the same temperature as the

reference. The power-compensation DSC has sample and reference pans in

separate cavities in a heat sink. Purge gas enters below the pan, flows

upward past the pan, and out through holes in the cover of the heat

sink. Signal instability can be caused by time-dependent dissimilarities

in the thermal environments of sample and reference pans. Near ambient

pressure, no instabilities occur. At higher pressures, however, the

flow and thermal properties of the purge gas are much different than at

lower pressures. Flow and convective turbulence near the sample and

reference pans cause significant time-dependent fluctuations in the

thermal environments.

Turbulence was minimized in the NBS instrument by altering the flow path

of the purge gas. Signal instability was reduced by a factor of 350 to

levels typical of ambient pressure operation. No reduction in detector

sensitivity resulted, however. Temperature calibration is affected by

high pressure, but in a repeatable fashion which can be corrected by

calculation or adjustment of instrument controls.

The development of the high pressure modification has been greeted with

enthusiasm by the manufacturer of the DSC and by users interested in

pressure DSC applications. We have applied the pressure DSC to the

development of new test methods for the evaluation of synfuels and

automotive lubricants.

Lubricant Degradation Mechanism

Highly formulated lubricants are often used to lubricate various high

load, high stress modern engines in various power trains. One of the

561-125
major causes of premature engine failure is lubricant breakdown which

causes corrosion, fatigue, wear, and sometime sudden seizure/ welding.

The object of this project is to develop test methods to measure and

understand the degradation of lubricants and their relationship with

engine wear/failures.

Conventional oil analysis techniques include infrared spectroscopy and

wear metal analysis by emission spectroscopy or ferrography. Emission

spectroscopy measures metal particles mostly less than 1 pm. Ferrographic

methods are effective only for iron (magnetic) wear particles at 1 pm or

above. All three techniques function reasonably well in clean oil

systems. With normal used oils contaminated by airborne particles,

oxidized oil components, and wear particles, analysis becomes difficult.

Recent ASTM round-robin results on oxidation and nitration in used oils

by infrared spectroscopy indicated complete disagreement among a score

of oil company laboratories. One major technical problem is how to set

condemning limits for various parameters that are measured. High levels

of wear metals in used oil indicate incipient seizure and the time to

failure may be very short. Oil analysis usually measures oxidative

degradation and sometimes contamination, but their relationship to wear

and failure are not clear.

During the past year, some key experiments were performed. A carefully

selected lubricant with known engine performance was degraded in the

laboratory under controlled conditions. Various state-of-the-art measurement techniques as well as conventional oil analysis methods were used

to follow the degradation pathway of the oil. Periodic samples were withdrawn and tested in NBS developed laboratory engine simulation

tests. We found a definite correlation between additive depletion and

increase in wear. Secondary interactions between additive decomposition

products and base oil oxidation products were able to provide additional

wear protection but not to maintain the load carrying capability of the

lubricant. Results are shown in figures 1 and 2.

In figure 1, (from left to right) the viscosity of the oil remains

relatively stable until about 120 hours. At that time, the viscosity

increases sharply to over 800 percent of the original oil viscosity.

The antioxidant capacity is measured by the Ford free-radical titration

method [1] which measures the ability of the oil to eliminate free

radicals. We see that the antioxidant capacity drops sharply under

oxidation at about 50 hours (antioxidant depletion/degradation). However,

it rises again to about half of the original values. This suggests

secondary reactions between the base oil and additive degradation products

to regenerate antioxidant species. The seizure load [2] indicates the

capacity of the lubricant to carry a certain load without seizure. The

data in figure 1 suggest that the seizure load decreases by 30 percent

in the first 50 hours coincident with the additive depletion. After 50

hours, test results suggest frequent seizures and erratic friction

traces and a clear seizure load was difficult to determine. The amount

of wear increases about 30 percent and remains level after 50 hours.

Differential infrared results on the phosphorus-sulfur bond (characteristic

of the anti-wear additive zinc dithiophosphate) suggests that the anti-wear

additive is exhausted in the first 50 hours. This confirms the observed

wear and seizure load measurement.

561-126
In figure 2, additional parameters measured in the same experiment are presented. The viscosity increase and the antioxidant capacity are shown for reference. The oxidation induction times are measured with

the NBS developed thin film oxygen uptake test which has demonstrated

correlation with engine oxidation results [3]. The oxidation induction

time drops quickly and reaches a minimum at about 20 hours. This decrease

in oxidation stability suggests additive depletion and is in agreement

with the antioxidant titration results. After 20 hours, the oxidation

stability of the oil increases gradually, again suggesting antioxidant

regeneration. Differential infrared measurements on carbonyl (carbonoxygen bond) suggest a continuous rise in the oxidation process independent of other processes. The total acid number measures the organic

acidic species formed under oxidation. The data in figure 2 indicate

stepwise increases with different slopes. The acidic species begin to

form at about the 75th hour with a steep slope. At about the 120th

hour, the formation rate decreases and the viscosity increase begins to

rise sharply. Average molecular weights as measured by GPC indicate a constant level until about the 130th hour.

These results are interesting and significant. Contrary to conventional

theories, drastic failure did not occur when all the additives were

exhausted. In fact, the original additives were exhausted in the first

40 hours, yet the viscosity failure did not occur until about 120 hours.

Coincident with the viscosity increase, the acidic species in the oil

reach a certain level (TAN = 12). The load carrying capacity, however,

appears to correlate with the additive depletion.

Controlled experiments with a single lubricant degradation suggest some condemning limits on used oil properties. Three new test procedures

have been developed and proven useful in oil analysis for engine condition

monitoring. Future work will test other lubricants and additives in an oxidation/wear coupled system.

NBS-Industry Cooperative Program on Lubricating Base Oil Composition

Effects on Performance

Results of this NBS work were reported at the ASTM Committee D-2 on Fuels and Lubricants meeting held in Phoenix, AZ, in December 1981, and

extensive interest was expressed by oil companies and the additive

industry. A cooperative study has been initiated between 11 companies

and NBS to relate chemical composition of lubricating base oils to

performance. This effort will capitalize on the NBS thin-film oxidation

test to study the effects of base oil chemical compositions on oxidation

stability.

The relationship between chemical composition of base oils and performance

is not now understood. On the average, only about two percent of the

selected crudes can be processed into lubricating base oils. Current

practice calls for constant crude source and processing technology to ensure quality. Each crude source change necessitates a complete engine

testing of all products for requalification. Sometimes the products

have to be modified and redeveloped. A basic understanding between

composition and performance can suggest alternate processing technology

to remove undesirable compounds and improve product performance.

561-127
Various re-refined lubricating base oils derived from different process

technology were used in conjunction with a commercial additive package.

Analytical data on chemical composition were gathered and correlated

with performance on oxidation stability. Single components as well as combinations were tested. Initial results indicated that polar compounds,

sulfur compounds, and aromatic compounds were critical to performance.

Straight line correlation with a correlation factor of 0.95 was obtained

for the predicted and measured oxidation stability using these re-refined

base’ oils. Additional data on a few virgin base oils, however, were insufficient to establish a separate correlation for virgin base oil

performance from different crude sources.

In the cooperative program, nine companies sent over 100 base oils to

NBS with associated analytical data. These virgin oils from various

crude sources and processing technologies were tested in the TFOUT and

the results correlated with the composition parameters. New insights were gained from the various functional dependencies of the parameters.

The amounts of saturates and sulfur compounds were shown to have the

major influence on the base oil response to additives.

Microoxidation Test and Chemiluminescence Studies

Oxidation of lubricating base oils has been a primary research area during the past year. A study of the effects of iron and copper on oil

oxidation was carried out using the Penn State microoxidation test.

This is a high temperature, thin-film test that simulates the conditions

in the cylinder wall/piston ring area of an engine. Tests on steel,

copper, and glass substrates showed iron to be a pro-oxidant and copper

to be an oxidation inhibitor under the conditions of the test. The

study also shed new light on the overall mechanism showing that the

process is comprised of three parts: primary oxidation; polymerization

of the oxidized products; and formation of oil insoluble products.

Previously polymerization and formation of insolubles have been considered

to be part of the same process. This work showed that while large

amounts of high molecular weight products were formed on glass, the

subsequent formation of insolubles required the presence of metals.

Interestingly, copper which inhibited primary oxidation was found to be

the stronger promoter of insolubles formation.

Further oxidation research is being undertaken using chemiluminescence

(CL), light given off by the reaction. The application of CL on liquid

phase oxidation of complex molecules is .new and shows much promise as a simple, sensitive, non-intrusive method for continuously monitoring the

oxidation process. Work this year has included preparation of an extensive literature review of CL, and design and construction of two instruments, a general-purpose CL oxidation apparatus and a high-pressure

oxidation cell in which CL is measured remotely via a fiberoptic probe.

This fiberoptic CL technique has exciting research implications as such

probes could potentially be placed into harsh environments such as automobile engines to study oil degradation under actual service conditions.

The general-purpose CL apparatus is modular in design with interchangeable

reaction cells. It is currently set up to study the hydrocarbon-metal

interface reactions and the basic mechanisms in organometal 1 ic species

561-128
formation. Techniques have been developed for calculation of activation

energies for both the initiation and propagation steps of the oxidation

chain reaction. In addition, the integral of the CL curve is apparently

proportional to the overall conversion measured by other thin film

oxidation tests.

Friction and Wear

Emphasis here has been in two areas: development of laboratory bench

test methods to study the friction and wear characteristics of model

compounds and lubricating oils; and elucidation of the chemical interaction mechanisms between lubricants and metal surfaces in wear contacts.

Two new microsample thin film wear tests were developed to study the

oxidation-wear coupled performance of lubricating oils. These tests use only six microliters of sample for each test. A microsample step loading

seizure test measures the load carrying capability of the lubricant. The

other test, measured the time to seizure for lubricants under boundary

lubrication conditions. Results of both tests correlate with ASTM

engine sequence HID test wear results.

A microsample sequential test is currently being developed to measure

the coefficient of friction modified lubricants, additives, model compounds,

and chemically active components derived from basestocks. Preliminary

tests are underway to measure the coefficient of friction of a set of

formulated lubricants with friction modifiers, demonstrated in engine

tests to have fuel economy benefits.

A study was conducted to determine the additive response of different

basestocks in friction and wear. The step loading seizure test which

had demonstrated correlation with engine test was used. It was found

that at low additive package concentration (0.5 percent), the different

basestocks gave different friction and wear values for the same additive.

A new wear debris analyses technique was developed to analyze the wear

products in a contact junction for organometal 1 ic components. This

technique combines gel permeation chromatography with graphite furnace

atomic absorption chromatography to determine the molecular weight range

of iron containing organometal 1 ic species under both static and dynamic

rubbing conditions.

Static Oxidation Test

Metal and metal 1 o-organic compounds are known to play important roles in

oxidation stability and degradation processes in lubrication. However,

detection systems previously employed were non-specific for metal

containing species that are generated during interactions between metals

and lubricants. A high sensitivity analytical system designed for such

purpose was built. Key features of the system involve separation of

analytes by high-performance size exclusion chromatography and continuous

effluent analysis of central metals or metalloids by graphite furnace

atomic absorption spectrophotometry. Auxiliary nonspecific and nondestructive detectors, i.e., refractive index and ultraviolet were also incorporated.

561-129
This approach was successfully applied to the static, thin film oxidation

reaction products. During this test 40 microliters of oil were added to

a metal disc 1.9 cm in diameter, contained in a glass reactor at 225 °C

under an air flow of 20 cc/min. The oil formed a 150 pm thin film on the metal disc. After selected time intervals, reaction was quenched, a solvent was added and the resulting solution was filtered and analyzed

with a SEC-RI-GFAA system. Figure 3 illustrates typical data generated

from this system when applied to oxidation on a copper disc for 15

minutes at 225 °C. Information may also be gathered on the distribution

and concentration of metals in the high molecular weight products as a function of time. This is illustrated for copper in figure 4. Studies

involving steel discs have provided data on metal uptake and molecular

weight distributions of high molecular weight products as shown in

figure 5. In all cases, the metal was shown to exist mainly in the high

(1000 to 100,000 MW) region. There was also different behavior for

copper and iron. In figure 4, the concentration of copper organometal 1 ic

compounds appear to decrease with time while the iron organic compounds

appear to increase with time (fig. 5).

Dynamic Rubbing Wear Test

The same analysis procedure was applied to a microsample thin film wear

test conducted at room temperature for a fully formulated motor oil.

The wear test was stopped at different times and the wear debris was

analyzed. The results are shown in figure 6. The iron again appears in

the same molecular weight region as in the static case with similarpatterns. This suggests high molecular weight metal -organometal 1 ic

compounds are formed in wear contacts at room temperature and the mechanisms appear to be similar to the static case at high temperatures. This

further implies that the temperature at the wear contact is considerably

higher than the room temperature confirming the existence of high "flash

temperatures" in the contact zone.

[1] Mahoney, L. R. ; et al. The determination of the antioxidant capacity

of new and used lubricants: method and application. Ind. Eng.

Chem. Prod. Res. Dev. 17: 250; 1978.

[2] Gates, R. S. ; Hsu, S. M. Development of a four-ball wear test

procedure to evaluate automotive lubricating oils. ASLE Preprint

No. 82-AM-6A-4, presented at the ASLE meeting; Cincinnati, OH.

1982 May.

[3] Ku, C. S. ; Hsu, S. M. A thin-film oxygen uptake test for the

evaluation of automotive lubricants. To be presented at the

ASLE/ASME joint conference; Washington, DC. 1982 October 7-9.

561-130
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561-131

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561-132

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561-134
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561-135
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561-136
Other Activities of the

Materials Chemistry Division

Invited Talks

A Rational Function Approximation of Powder Diffraction Profiles

American Crystallographic Association, Washington, DC

N. C. Panagiotopoulos and C. R. Hubbard

March 1981

JCPDS-International Centre for Diffraction Data

International Union of Crystallography, Ottawa, Canada

C. R. Hubbard

August 1981

An Assessment of Materials Requirements and Research Needs for Open

Cycle MHD Systems

Symposium on the Chemistry of Materials at High Temperatures, Harwell,

Cambridge, England

S. J. Schneider

September 1981

El 1 ipsometric Studies on the Air-formed Film on Iron

Bell Labs., Murray Hill, NJ

J. J. Ritter

September 1981

On the Mechanism of Transgranular Stress-Corrosion Cracking in AlphaBrass

Second International Conference on Environmental Degradation of

Engineering Materials, Virginia Polytechnic Institute and State

University, Blacksburg, VA

E. N. Pugh

September 22, 1981

Time Evolution of the Atom Density "Hole" Following Laser Enhanced

Ionization in Flames

Federation of Analytical Chemistry and Spectroscopy Societies (FACSS),

Philadelphia, PA

J. C. Travis, G. C. Turk, and P. K. Schenck

September 24, 1981

X-ray Analysis of Selected RDF and Coal Samples as a Function of

Temperature

Symposium on Resource Recovery and Environmental Issues of Industrial

Solid Wastes, Oak Ridge, TN

C. R. Robbins, E. Domalski, and R. Kelly

October 1981

Information Systems for Fossil Energy Materials Applications

Sixth Annual Conference on Materials for Coal Conversion and Utilization, National Bureau of Standards, Washington, DC

H. M. Ondik

October 1981

561-137
Arc Plasma Sprayed Ceramic Coatings

Sixth Annual Conference on Materials for Coal Conversion and Utilization, National Bureau of Standards, Washington, DC

T. Negas

October 1981

Unusual Luminescence Behavior of Terbium Phosphate Glasses

Fall Meeting, American Ceramic Society, Bedford Springs, PA

D. J. Cronin, D. H. Blackburn, and W. K. Haller

October 2, 1981

Graphics on the 9825 Computer

Desktop Computer Users Group, Hewlett Packard Co., Rockville, MD

P. K. Schenck

October 6, 1981

Optogalvanic Spectroscopy

Highlands in Chemistry Seminar, Virginia Polytechnic Institute,

Blacksburg, V

A

P. K. Schenck

October 8, 1981

Powder Processing of Potassium Aluminosilicate

Fall Meeting, Basic Science Division, American Ceramic Society,

Louisville, KY

L. P. Cook

October 11, 1981

SEM, TEM, and STEM Investigation of Sintering in Anorthite

Fall Meeting, Basic Science Division, American Ceramic Society,

Louisville, KY

L. P. Cook

October 12, 1981

Research Applications of High Pressure Sampling Mass Spectroscopy

to Cluster Nucleation

NBS Aerosol /Smal 1 Particle Seminar, NBS, Washington, DC

D. W. Bonnell

November 1981

Mass Spectrometric Studies of MHD Slag Thermochemistry

MHD Specialists Meeting, Sydney, Australia

J. W. Hastie

November 1981

Why A Career In Chemistry?

Department of Chemistry, Western Maryland College, Westminster, MD

J. A. Jackson

November 4, 1981

Speciation of Arsenic in Fossil Fuels and Their Conversion Process Fluids

Arsenic Symposium, sponsored by Chemical Manufacturing Association

and NBS, National Bureau of Standards, Gaithersburg, MD

C. S. Weiss

November 6, 1981

561-138
Mechanisms of Stress-Corrosion Cracking in FCC Alloys

Materials Frontier Seminar, North Carolina State University, Raleigh, NC

E. N. Pugh

November 13, 1981

Preparation of Thin Amorphous Films by E-Beam Evaporation from

Multiple Sources

13th Boulder Laser Damage Symposium, Boulder, CO

E. N. Farabaugh, D. M. Sanders, M. E. Wilke, S. A. Hurwitz, and

W. K. Haller

November 17, 1981

Index, Thickness, and Birefringence of Thin Films by Guided Waves

13th Boulder Damage Symposium, Boulder, CO

A. Feldman and E. N. Farabaugh

November 17, 1981

Test Methods for Lubricant Degradation

American Society of Lubrication Engineers, Baltimore Section Meeting,

Baltimore, MD

S. M. Hsu

November 19, 1981

Physics and Chemistry of a Thin Film Wear

Wear Topical Conference Meeting, Poster Session, American Physical

Society, New Orleans, LA

R. G. Gates

November 23-24, 1981

Recent Advances in High Temperature Chemistry

Chemistry Department, University of Tasmania, Sydney, Australia

J. W. Hastie

December 1981

Use of MHD Materials Science Development in Other Technical Areas

AIAA, Colorado Springs, CO

S. J. Schneider

December 3, 1981

Relationship Between Composition and Performance for Re-refined Base

Oi 1 s American Society for Testing and Materials Annual Meeting, Committee

D-2, Phoenix, AZ

S. M. Hsu

December 10, 1981

Electrochemical Noise Measurements

Conference on Electrochemical Methods in Corrosion Testing and

Research, Manchester, United Kingdom

U. Bertocci

January 5, 1982

The Molecular Speciation of Trace Elements in Synthetic Fuels

Mobil Corporate Research Center, Princeton, NJ

C. S. Weiss

January 8, 1982

561-139
Pressure Studies at High and Low Temperatures

University of Paderborn, Federal Republic of Germany

G. Piermarini

February 2, 1982

Current Understanding of Stress-Corrosion Cracking

Mechanical and Materials Engineering Seminar. Vanderbilt University,

Nashville, TN

E. N. Pugh

February 3, 1982

Chemical Nomenclature: Who Cares and Why?

American Chemical Society, Wilson Dam Section, Florence, AL

T. D. Coyle

March 1982

Environmental Aspects of Organometal 1 ic Chemistry

Chemistry Department, University of Alabama, Birmingham, AL

T. D. Coyle

March 1982

Currents in Corrosion Research

American Chemical Society, Mobile Section, Mobile, AL

T. D. Coyle

March 1982

A Rational Function Approximation of Powder Diffraction Profiles

American Crystallographic Association, Washington, DC

N. C. Panagiotopoulos and C. R. Hubbard

March 1982

The Corrosion of Organically Coated Iron and Steel: An El 1 ipsometric

Study of the Subcoating Oxide Film Behavior

Corrosion '82, NACE, Houston, TX

J. J. Ritter

March 1982

Inorganic Ion-Doped Glass Beads as Microspectrofluorimetric Standards

1982 Pittsburgh Analytical Conference, Atlantic City, NJ

D. K. Hancock, R. A. Velapoldi, J. R. DeVoe, and D. H. Blackburn

March 9, 1982

High Pressure Phases and Properties

Howard University, Washington, DC

S. Block

March 11, 1982

Characterization of Organometal 1 ic Polymers by 13 C and 119 Sn NMR

Department of Chemistry, University of Delaware, Newark, DE

R. B. Johannesen

March 19, 1982

561-140
Aqueous Solutions of Organometal s: Implications for Cellular Uptake

Membrane Bioenergetics Group, Lawrence Berkeley Laboratory, University of California, Berkeley, CA

F. E. Brinckman

March 22, 1982

Advances in Speciation of Organometal 1 ics and Metal -Containing Macromolecules in Fossil Materials and Process Fluids

Energy and Environment Division, Lawrence Berkeley Laboratory,

University of California, Berkeley, CA

F. E. Brinckman

March 23, 1982

The Use of Load Pulsing in the Study of Stress-Corrosion Phenomena

NACE Corrosion Research Conference, Houston, TX

P. W. Slattery

March 24, 1982

Pit Initiation and Propagation Rates of 304 Stainless Steel in

Chloride Environments

NACE, Houston, TX

K. A. Rhyne

March 24, 1982

Incorporation of Arsenic in Metal -Containing Macromolecules in Shale

Oil as Determined by Multielement-Specific Size Exclusion Chromatography

Symposium on Petroleum Biogeochemistry, 183rd National Meeting

American Chemical Society, Las Vegas, NV

C. S. Weiss

March 29, 1982

Immersion Deposition on Aluminum

Aluminum Finishing Seminar, St. Louis, MO

D. S. Lashmore

March 30, 1982

Analytical Implications of the Signal Collection Process in Laser

Enhanced Ionization

183rd National Meeting, American Chemical Society, Las Vegas, NV

J. C. Travis, G. J. Havrilla, G. C. Turk, and P. K. Schenck

March 31, 1982

Preparation of Amorphous Coatings by Coevaporation

Optical Thin Film Workshop, University of New Mexico, Albuquerque, NM

D. M. Sanders, E. N. Farabaugh, and W. K. Haller

April 21, 1982

Development of an NBS Microhardness Standard

Conference on Microhardness Testing, NBS, Washington, DC

D. S. Lashmore

May 1982

561-141
Characterization of Slag and Fouling Residues from Co-combustion of

Powdered Refuse-derived Fuel with Residual Oil and Comparison with

Coal and RDF Residues

Symposium on Resource Recovery from Municipal, Hazardous, and Coal

Solid Wastes, Miami, FL

C. R. Robbins and F. Hasselriis

May 1982

Thermodynamic Models of Glass Vaporization

American Ceramic Society, 84th Annual Meeting, Symposium on Glass

Modeling, Cincinnati, OH

J. W. Hastie

May 1982

A Comparison of Optical and Mechanical Methods of Thickness Measurement

Society of Photo-Optical Instrumentation Engineers Technical Symposium,

Arlington, VA

A. Feldman and T. Vorburger

May 5, 1982

NMR Examination of Organometal 1 ic Copolymers

Naval Biosciences Laboratory, Oakland, CA

R. B. Johannesen

May 5, 1982

A Study of the Underground Corrosion of Copper Concentric Cable

Central Maryland Underground Corrosion Committee Meeting, Baltimore, MD

E. Escalante

May 5, 1982

Ceramic Films by Multi-Source Evaporation

Society of Photo-Optical Instrumentation Engineers Technical

Symposium, Arlington, VA

D. M. Sanders, E. N. Farabaugh, and W. K. Haller

May 6, 1982

Development of a Four-Ball Wear Test Procedure to Evaluate Automotive

Lubricating Oils

American Society of Lubrication Engineers, Cincinnati, OH

R. G. Gates

May 10-13, 1982

Corrosion Protection Principles and the Development of New Coatings

American Society of Metals SURTECH and SURFACE Coating Exposition,

Dearborn, MI

J. Kruger

May 18, 1982

Activity and Phase Equilibria Models in Complex Silicate Systems

CALPHAD XI, Argonne National Laboratories, Chicago, IL

L. P. Cook and J. W. Hastie

May 18, 1982

561-142
An Examination of the MCC-1 Leach Test Method, Part III Comparison

of Glass Composition

Second Semi-annual Workshop on Leaching Mechanisms of Nuclear Waste

Forms, Battelle Pacific Northwest Labs., Richland, WA

D. J. Cronin

May 19, 1982

Standards for X-ray Powder Diffraction

X-ray Clinic, State University of New York, Albany, NY

C. R. Hubbard

June 1982

Ceramics and Glass Program at NBS

Refractories Research Center, Ohio State University, Columbus, OH

T. D. Coyle

June 1, 1982

Ceramics and Glass Program at NBS

PPG Industries, Pittsburgh, PA

T. D. Coyle

June 2, 1982

Ceramics and Glass Program at NBS

Alcoa Technical Center, Pittsburgh, PA

T. D. Coyle

June 3, 1982

Mass Spectrometric and Thermodynamic Modeling Studies of Glass

NBS Seminar, Washington, DC

J. W. Hastie

June 9, 1982

Characterization of Organometal 1 ic Copolymers and Copolymerization

by Size Exclusion Chromatography

Sixth International Symposium on Column Liquid Chromatography,

Cherry Hill, NJ

E. J. Parks

June 10, 1982

Mass Spectrometric and Thermodynamic Modeling Studies in Glass

Saint-Gobain Research Labs., Paris, France

J. W. Hastie

June 14, 1982

Further Observations on the Mechanisms of Transgranular StressCorrosion Cracking

Sixth Canadian Fracture Conference (Time Dependent Fracture of

Engineering Material s--Environmental Effects), Vancouver, BC, Canada

E. N. Pugh

June 17, 1982

Nuclear Waste Encapsulation

EG&G, Inc., Idaho International Engineering Lab., Idaho Falls, ID

R. S. Roth

June 23, 1982

561-143
Transpiration Mass Spectrometry--A New Thermochemical Tool

NATO Scientific Affairs Division, Thermochemistry School, Viana do

Castelo, Portugal

J. W. Hastie

July 1982

Thermodynamic Modeling of High Temperature Silicate Vaporization

NATO Scientific Affairs Division, Thermochemistry School, Viana do

Castelo, Portugal

J. W. Hastie

July 1982

Modeling of Silicate Solutions

Gordon Research Conference on High Temperature Chemistry, Tilton, NH

J. W. Hastie

July 1982

High Temperature Chemistry Research at NBS

Boris Kidrich Institute of Nuclear Physics, Belgrade, Yugoslavia

J. W. Hastie

July 1982

Ceramics and Glass Program at NBS

Sandia National Laboratory, Albuquerque, NM

S. J. Schneider

July 1, 1982

13 C and 119 Sn Nuclear Magnetic Resonance

Workshop on Characterization of Organometal 1 ic Polymers, Naval

Research Laboratory, Washington, DC

R. B. Johannesen

July 20, 1982

Tin-Specific Size Exclusion Chromatography

Workshop on Characterization of Organometal 1 ic Polymers, Naval

Research Laboratory, Washington, DC

E. J. Parks

July 20, 1982

Fuel Stability Measurement Methods by Differential Scanning Calorimetry and Thermal Gravimetric Analysis

CONFAB 82, Saratoga, WY

S. M. Hsu

July 21, 1982

Fragmentation Temperature Dependence in Electron Impact Ionization of

Molecular Beams

Gordon Research Conference on High Temperature Chemistry, Tilton, NH

D. W. Bonnell

July 26, 1982

Electrodeposition of Nickel Chromium Alloys

Read Conference, University of Pennsylvania, University Park, PA

D. S. Lashmore

July 28, 1982

561-144
Measurement and Interpretation of Electrochemical Noise

Gordon Research Conference on Corrosion, New London, NH

U. Bertocci

July 30, 1982

XRD Quantitative Phase Analysis Using the NBS Quant 82 System

Denver X-ray Conference, Denver, CO

C. R. Robbins, C. R. Hubbard, and R. L. Snyder

August 1982

X-ray Diffraction Analysis and Particle Size Distribution of Fossil

Energy Waste Samples

US DOE Laramie Energy Technology Center, Laramie, WY

C. R. Robbins

August 1982

Energy-Dispersive X-ray Microanalysis by the Peak-to-Background Method:

Empirical Corrections for Detector-Degraded Background Counts

Electron Microscopy Society of America, Washington, DC

M. C. Foster, W. A. Hagins, and D. H. Blackburn

August 11, 1982

The Aqueous Chemistry of Biogenic Organometals

Gordon Research Conference on Organometal 1 ic Chemistry, Andover, NH

F. E. Brinckman

August 19, 1982

Pit and Crevice Corrosion of 304 Stainless Steel in Chloride Environment as Determined by Electrochemical Techniques

Nippon Steel Corporation, Kawasaki, Japan

K. A. Rhyne

August 27, 1982

Pit and Crevice Corrosion of 304 Stainless Steel in Chloride Environment as Determined by Electrochemical Techniques

Tokoku University, Sendai, Japan

K. A. Rhyne

August 30, 1982

Anaerobic Corrosion

21st Annual Conference of Metallurgists, Toronto, Ontario, Canada

W. P. Iverson

September 1, 1982

Defects and Charge Transport in Stabilized (y-Ta 2 0 5 Fourth Europhysical Topical Conference on Lattice Defects in Ionic

Crystals, Trinity College, Dublin, Ireland

A. E. McHale

September 2, 1982

HPLC-AA: Keying on Ultratrace Bioactive Molecules by Element Selection

9th Annual Meeting, Federation of Analytical Chemistry and Spectroscopy

Societies, Philadelphia, PA

F. E. Brinckman

September 22, 1982

561-145
Division Seminars

The Division maintains an active Seminar Program in which lectures by

distinguished visitors on scientific topics of interest to the Division

are supplemented by presentations of current work by Division scientists.

In FY82, the Division sponsored almost three seminars per month, of which

two-thirds were presented by scientists from outside NBS.

Recent Studies of Stress-Corrosion Cracking and Liquid-Metal Embrittlement

Stan Lynch

Aeronautical Research Laboratories, Melbourne, Australia

September 30, 1981

Recent NMR Studies of Graphite Intercalation Compounds

Gerald Miller

University of Maryland, College Park, MD

October 22, 1981

Studies by Auger Spectroscopy and Channeling of Si and GaAs Surfaces

Bernard Agius

Institut d' Electronique Fondamentale, Universite Paris XI, France

October 22, 1981

Theoretical and Experimental Studies of Crack Electrochemistry in

Structural Steels in a Marine Environment

A. Turnbull

National Physical Laboratory, Teddington, Middlesex, England

October 28, 1981

The Use of Ultramicrotomy in Studying Sections of Filmed and Corroded

Surfaces

Graham C. Wood

University of Manchester, Manchester, England

November 3, 1981

The Activities and Operations of the Corrosion and Protection Centre

at the University of Manchester Institute of Science and Technology

Graham C. Wood

University of Manchester, Manchester, England

November 3, 1981

Pulsed Electrodeposition of Palladium

J. M. Locarnini

Technisch Chemisches Laboratori urn, Swiss Federal Institute of

Technology, Zurich, Switzerland

November 6, 1981

Some Measurement Techniques for Fuel Stability Characterization

A. L. Cummings, P. Pei, and S. M. Hsu

National Bureau of Standards, Gaithersburg, MD

November 20, 1981

561-146
Program of the Structural Chemistry Group

S. Block, G. J. Piermarini, F. A. Mauer, and R. G. Munro

National Bureau of Standards, Gaithersburg, MD

November 24, 1981

Some Effects of Oxidation on the Wear Behavior of Base Stocks and

Additi ves

P. A. Willermet

Ford Motor Company, Dearborn, MI

December 4, 1981

Current Research in the Chemical and Biodegradation Processes Group

F. E. Brinckman, R. B. Johannesen, and G. J. Olson

National Bureau of Standards, Gaithersburg, MD

December 17, 1981

Characterization of Surface Properties of Importance in Tribology

Donald Buckley

National Aeronautics and Space Administration, Lewis Research Center,

Cleveland, OH

January 7, 1982

Activities of the Glass and Optical Materials Group

W. K. Haller, M. J. Cellarosi, D. H. Blackburn, D. J. Cronin,

E. R. Farabuagh, A. Feldman, and D. H. Sanders

National Bureau of Standards, Gaithersburg, MD

January 25, 1982

Determination of Molecular Constants by Matrix Isolation NMR Spectroscopy

Kurt W. Zilm

University of Utah Research Center, Salt Lake City, UT

February 9, 1982

Experimental and Theoretical Compi lational Activities in Phase Equilibria of Ceramic Systems

R. S. Roth, L. P. Cook, and A. McHale

National Bureau of Standards, Gaithersburg, MD

February 11, 1982

Vapor Pressure Measurement Above Nuclear Fuels at 5000 to 7000 K

J. F. Babelot

Karlsruhe Establishment, Europena Institute for Transuranium Elements,

Federal Republic of Germany

March 19, 1982

A-C Anodizing of Aluminum

Joeph Zahavi

Israel Institute of Metals, Technion City, Haifa, Israel

April 12, 1982

Current Research in Corrosion Group

J. Kruger, U. Bertocci , E. Escalante, V. K. Hardman, E. N. Pugh, and

J. J. Ritter

National Bureau of Standards, Gaithersburg, MD

April 13, 1982

561-147
Corrosion Problems in Ethanol Fuel Powered Cars

Deniol K. Tanaka

Instituto de Pesquisas Tecnologicas , Sao Paulo, Brazil

April 20, 1982

Activities of the Ceramic Processing and Durability Group

T. Negas

National Bureau of Standards, Gaithersburg, MD

April 29, 1982

Stress Corrosion Cracking of Mg Alloys

K. J. Barton

University of Wyoming, Laramie, WY

May 6, 1982

Structure and Mechanical Properties of Stainless Steel

James Y. L. Chen

12216 Devil Wood Drive, Potomac, MD

May 11, 1982

Plasmid Determined Mercury Resistance

Anne Summers

Department of Microbiology, University of Georgia, Athens, GA

May 24, 1982

Elasticity and Small Angle Neutron Scattering Measurements in YCr03

Eldon Case

National Bureau of Standards, Gaithersburg, MD

May 24, 1982

Electrodeposition Research at NBS

David S. Lashmore

National Bureau of Standards, Gaithersburg, MD

May 28, 1982

Mass Spectrometric and Thermodynamic Modeling Studies of Glass

Vapori zation

John W. Hastie

National Bureau of Standards, Gaithersburg, MD

June 9, 1982

Sintering and Grain Growth

R. Coble

Massachusetts Institute of Technology, Cambridge, MA

July 13, 14, and 15, 1982

Anodic Dissolution in Stress-Corrosion Cracking Processes

J. R. Galvele

Comision Nacional de Energia Atomica, Buenos Aires, Argentina

August 2, 1982

561-148
Technical and Professional Committee Memberships

American Ceramic Society

Ad Hoc Committee on Phase Equilibria Data Center

L. P. Cook, Chairman

Committee on Glass Standards Classification and Nomenclature

M. J. Cellarosi, Chairman

Committee on Government Liaison

M. J. Cellarosi, Member

Committee on Publications

Subcommittee on "Phase Diagrams for Ceramists"

R. S. Roth, Chairman

Development Committee

S. J. Schneider, Member

Refractories Division

S. J. Schneider, Editorial Chairman

Research Committee (Phase Diagrams)

L. P. Cook, Chairman

American Chemical Society

Inorganic Chemistry Division—Nonmenclature Committee

T. D. Coyle, Chairman

Nomenclature Committee

T. D. Coyle, Member

American National Standards Institute (ANSI)

Committee N43 —Equipment for Ionizing Radiation

S. Block, Member

Committee 43.1--Safety Standards for X-ray Diffraction and

Fluorescence Analysis Equipment

S. Block, Chairman

F. A. Mauer, Secretary

American Petroleum Institute and American Society for Testing and

Materials

Joint Committee on Static Petroleum Measurement, Working

Group on Water and Sediment

J. J. Comeford, Member

American Society for Metals

Board of Review, Metallurgical Transactions

E. N. Pugh, Member

American Society for Testing and Materials

B08: Electrodeposited Metallic Coatings and Related Finishes

D. S. Lashmore, Member

B08.01: Terminology, Editing Public Relations

and Metrication

WG.05: Metrication, Chairman

B08.02: Substrate Preparation

B08.03: Decorative Copper, Nickel, Chromium,

and Nickel -Chromium Coatings

WG: Electrodeposited and Electroless

Black Coatings for Solar Use

561-149
C5:

C8:

C9:

C14:

C18:

D2:

B08.04: Zinc and Cadmium Coatings

B08.05: Coatings of Tin, Lead, and Their Alloys

B08.06: Anodic and Chemical Conversion

Coatings on Aluminum and Magnesium

Alloys

Engineering Coatings

Precious Metal Coatings

General Test Methods

WG.01: Measurement of Coating

Thickness, Chairman

Government Specifications, Chairman

Technical Advisory Groups to ISO/TC 107

F. Ogburn, Member

Manufactured Carbon and Graphite Products

W. S. Horton, Member

B08.08

B08.09

B08.10

B08.ll:

B08.20:

C5.02: and Editorial

Member

Aggregates

Nomenclature, Units

Matters, Chairman

C5.05: Nuclear Applications

C5.06: Executive Subcommittee

W. S. Horton, Member

Refractories

Awards Committee

S. J. Schneider, Chairman

Conditions of Tests

S. J. Schneider, Member

Speci ficati ons

S. J. Schneider,

Concrete and Concrete

C. R. Robbins, Member

Glass and Glass Products

M. J. Cellarosi, Chairman

C14.01: Nomenclature of Glass and Glass Products

M. J. Cellarosi, Chairman

C14.03: Chemical Properties of Glass

W. K. Haller, Member

C14.04: Physical and Mechanical Properties of Glass

M. J. Cellarosi, Member

D. J. Cronin, Member

C14. 08: Flat Glass

M. J. Cellarosi, Member

Natural Buildng Stones

C. R. Robbins, Member

C18:0304: Sandstone

C. R. Robbins, Member

C18.07: Environmental Properties, Behavior and Cleaning

C. R. Robbins, Member

Petroleum Products and Lubricants

S. M. Hsu, Member

T-B: Automotive Lubricants

T-B-II: Heavy Duty Engine Oils

T-Jt.B/P: Basestock Characterization

T-P: Recycled Petroleum

T-P-II: Used Oils and Basestocks

T- P- III: Fuel Oils

561-150
Elemental Analysis

Flow Properties

Oxidation

RDD-II:

RDD-IV:

RDD-IX:

C. Ku, Member

R. S. Gates, Member

T-L: Industrial Lubricants

J. J. Comeford, Member

T-E-I: Burner Fuel Oils

RDD-IV: Hydrocarbon Analysis

RDD-IV-F: Absorption Spectroscopy Methods

T-P: Recycled Petroleum Products and Lubricants,

Advisory, Vice-Chairman

T-P-I: Automotive Lubricants

T-P-II: Used Oils and Base Stocks

T- P— III: Fuel Oils, Chairman

T-P-IV: Industrial and Hydraulic Oils

T-P-VI: Miscellaneous Products

T-P-VII: Editorial

RDD-IX-F: Used Oils Oxidation-Nitration

RDD-III: Elemental Analysis

.. Cummings, Member

RDD-III-A: Chemical Methods

RDD-III-C: Electrometric Method

RDD-VI-A: Chemical Analysis

Jt.API/ASTM: Water and Sediment

S. Pei, Member

RDD-III: Elemental Analysis

RDD-III-A: Chemical Methods

RDD-IV: Hydrocarbon Analysis

RDD-IV-A: Chemical Analysis

RDD-IV-C: Liquid Phase Chromatography

RDD-VI: Analysis of Lubricants

Weeks, Member

T-P: Recycled Petroleum Products

RDD-III: Elemental Analysis

RDD-IV: Hydrocarbon Analysis

RDD-VII: Flow Properties

E13: Molecular Spectroscopy

R. B. Johannesen, Member

E13.07: Nuclear Magnetic Resonance, Member

E19: Chromatography

E. J. Parks, Member

E20: Temperature

S. J. Schneider, Member

E34: Occupational Health and Safety Aspects of Materials,

Physical and Biological Agents

F. E. Brinckman, Member

E38: Resource Recovery

M. J. Cellarosi, Member

C. R. Robbins, Member

E38.06.03: Fly Ash in Construction Materials

C. R. Robbins, Member

E44: Solar Heating and Cooling

FI. 02: Laser

A. Feldman, Member

561-151
E47: Biological Effects and Environmental Fate

F. E. Brinckman, Member

G. J. Olson, Member

G01: Corrosion of Metals

U. Bertocci , Member

G01.ll: Electrochemical Measurements in Corrosion Testing

U. Bertocci, Member

E. Escalante, Member

G01.10: Corrosion in Soils

E. Escalante, Chairman

G01.10: Corrosion in Soils

TG: Electrochemical Polarization

Techniques for Measurement of

Corrosion Rates in Soils

W. P. Iverson, Chairman

J. Kruger, Member

G01.02: Nomenclature

G01.90: Executive Committee

G01.99: Standing Committee on Liaison, Chairman

E. N. Pugh, Member

G01.06: Stress Corrosion Cracking and Corrosion Fatigue

E. N. Pugh, Vice-Chairman

Carnegie Mellon Institute of Research

Industrial Energy Productivity Project: Materials Trends Group

J. Kruger, Member

Center for Surface and Coatings Research, Lehigh University

Visiting Committee

J. Kruger, Member

Committee on Recommendations for U.S. Army Basic Scientific Research

J. Kruger, Member

Corrosion, Surfaces, and Interfaces Section

J. Kruger, Chairman

Corrosion Research Center, University of Minnesota

External Advisory Panel

J. Kruger, Member

Electric Power Research Institute

Corrosion Advisory Committee

J. Kruger, Member

Electrochemical Society

J. Kruger, National Treasurer

Board of Directors

J. Kruger, Member

Corrosion Division Award Committee

J. Kruger, Chairman

Corrosion Monograph Series Committee

J. Kruger, Chairman

561-152
Editorial Committee

J. Kruger, Member

U. Bertocci , Member

Executive Committee

J. Kruger, Member

Finance Committee

J. Kruger, Chairman

Financial Policy Advisory Committee

J. Kruger, Member

01 in Patterson Award Committee

U. Bertocci, Member

Federation of Materials Societies

J. Kruger, Trustee

Long-Range Planning Committee

J. Kruger, Member

Tenth Anniversary Committee

J. Kruger, Chairman

Gordon Research Conferences

Counci 1 J. Kruger, Member

Society Meeting Committee

J. Kruger, Member

High Temperature Science and Energy Technology

Editorial Advisory Board

J. W. Hastie, Member

InterAmerican Conferences on Materials Technology

Executive Committee

S. J. Schneider, Member

International Commission on Glass

Subcommittee A. II: Durability and Analysis

W. K. Haller, Member

Subcommittee VIII: Standard Reference Glasses

W. K. Haller, Vice Chairman

U.S. Representative

W. K. Haller

International Corrosion Council

J. Kruger, Member & U. S. Delegate

International Standards Organization

TC107: Metallic and Other Non-organic Coatings

D. S. Lashmore, Delegate

1: Terminology

2: Methods of Inspection and Coordination of Test

Methods

3: Electrodeposi ted Coatings and Related Finishes

7: Corrosion Tests

D. S. Lashmore, Delegate

561-153
TC156: Corrosion of Metals

J. Kruger, Delegate

1: Terminology

J. Kruger, Delegate

International Society of Electrochemistry

Corrosion Division

U. Bertocci , Co-Chairman

International Union of Crystallography

Commission on Crystallography at Controlled Pressures and Temperatures

G. J. Piermarini, Member

International Union of Pure and Applied Chemistry

Commission I

I - 2 : Nomenclature of Inorganic Chemistry

T. D. Coyle, Titular Member, Secretary

Commission I I- 3 : High Temperature Chemistry Refractory Materials

J. W. Hastie, Associate Member

Interdi visional Committee on Nomenclature and Symbols

T. D. Coyle, Titular Member

Conferences on Refractories for Energy Applications

Planning and Program Committees

S. J. Schneider, Member

JCPDS-International Centre for Diffraction Data

S. Block, Member

C. R. Hubbard, Member and Vice-Chairman

Board of Directors

Technical Committee

Long-range Planning Committee

Ceramics Subcommittee

Data Collection and Analysis Subcommittee

Data Base Subcommittee

Search/Match Methods Subcommittee

Joint Committee of Atomic and Molecular Physical Data

NMR Subcommittee

R. B. Johannesen, Chairman

Joint Electron Devices Engineering Councils

X-ray and Implosion TV Standards Committee

M. J. Cellarosi, Member

Journal of Physical and Chemical Reference Data

Editorial Board

H. M. Ondik, Member

The Metals Properties Council, Inc.

Subcommittee 9 —Coal Conversion

S. J. Schneider, Member

Task Group on Corrosion Fatigue Testing

E. N. Pugh, Member

561-154
The Metallurgical Society of AIME

Corrosion and Environmental Effects Committee

E. N. Pugh, Member

National Association of Corrosion Engineers

Awards Committee

J. Kruger, Member

Standing Committee on Technology Assessment

J. Kruger, Chairman

J. L. Mullen, Member

T3: Corrosion Science and Technology

K. A. Rhyne, Member

T3L: Electrochemical and Electrical Techniques for

Corrosion Measurement and Control

W. P. Iverson, Member

J. Kruger, Member

T10: Underground Corrosion Control

E. Escalante, Member

Technical Practices Committee

J. Kruger, Member

National Research Council

Committee on High Temperature Science and Technology

J. W. Hastie, Chairman

National Materials Advisory Board

Committee on Environmentally Assisted Cracking Test: Methods for

High Strength Steel Weldments

J. Kruger, Member

E. N. Pugh, Liaison Representative

Committee on Fuel Cell Materials Technology in Vehicular

Propulsion

U. Bertocci , Liaison Representative

Committee on Mineral Resources Technology

S. J. Schneider, Liaison Representative

National Materials Review Board (MRB) for Nuclear Waste

Data and Testing Procedures Committee

T. Negas, Member

Optical Society of America

Committee on Standards

A. Feldman, Member

Read Research Conferences

Organizing Committee

D. S. Lashmore, Member

SERI

Committee on Use of Solar Furnace Facility

J. W. Hastie, Member

U. S. /U. S. S. R. Study Group on Corrosion

Passivity and Electrochemistry Project

J. Kruger, Coordinator

561-155
U. S. /U. S. S. R. Cooperative Program on MHD

Steering Committee

S. J. Schneider, Member

Publications

Bertocci , U. Noise in electrochemical systems. Meyer, P. H. E; Mountain, R. D. ; Soulen, Jr., R. J. , eds. Proceedings of the 6th

international conference on noise in physical systems; 1981 April 6-10;

Gaithersburg, MD. Nat. Bur. Stand. (U.S.) Spec. Publ. 614; 1981

September, p. 328.

Blair, W. R. ; Jackson, J. A.; Olson, G. J. ; Brinckman, F. E.

;

Iverson, W. P. Biotransformations of tin. Ernst, W. H. 0., ed. Proceedings of the 10th international conference on heavy metals in the

environment; 1981; Edinburgh, Scotland. C.E.P. Consultants, Publ.;

1981. p. 235.

Brinckman, F. E. Environmental organotin chemistry today: experiences

in the field and laboratory. J. Organomet. Chem. Libr. 12: 343; 1981.

Cava, R. J. ; Himes, V. L. ; Mighell, A. D. ; Roth, R. S. FeNb 3 Se 10 : a new structure type related to NbSe 3

. Phys. Rev. B: Condens. Matter 24:

24; 1981.

Ciaraldi, S. W. ; Nelson, J. L. ; Yeske, R. A.; Pugh, E. N. Studies of

hydrogen embrittlement and stress-corrosion cracking in an aluminumzinc-magnesium alloy. Bernstein, I. M. ; Thompson, A. W. , eds. Hydrogen

effects in metals: proceedings of the 3rd international conference on effects of hydrogen on behavior of materials; 1980 August 26-31;

Moran, WY. Metal 1. Soc. AIME 47EFA2; 1981. p. 437.

Filby, R. H. ; Sandstrom, D. R. ; Lytle, F. W. ; Greegor, R. B.

;

Kahlil, S. R. ; Ekambaram, V.; Weiss, C. S. ; Grim, C. A. Chemistry of

trace element species in coal liquefaction processes. Brinckman, F. E.

;

Fish, R. H. , eds. Proceedings of the 10th D0E/NBS workshop on environmental speciation and monitoring needs for trace metal -containing

substances from energy-related processes; 1981 May 18-20; Gaithersburg,

MD. Nat. Bur. Stand. (U.S.) Spec. Publ. 618; 1981 November, p. 21.

Fujishiro, I.; Piermarini, G. J. ; Block, S. ; Munro, R. G. Viscosity

and glass transition pressure of the methanol-ethanol-water system.

Proceedings of the 22nd high pressure conference of Japan; 1981

November 17-19; Hiroshima, Japan. 1981.

Hubbard, C. R. ; Calvert, L. D. The Pearson Symbol. Bull. Alloy Phase

Diagrams 2: 153; 1981.

Hsu, S. M. Review of laboratory bench tests in assessing the perfor- mance of automotive crackcase oils. J. Am. Soc. Lubr. Eng. 37: 722; 1981

Iverson, W. P. An overview of the anaerobic corrosion of underground

metallic structures: evidence of a new mechanism in underground cor- rosion, chapter in Underground corrosion. Escalante, E. , ed. Am. Soc.

Testing Mater. Spec. Tech. Publ. 741; 1981. p. 33.

561-156
Jewett, J. L. ; Brinckman, F. E. Speciation of trace di- and triorganotins in water by ion exchange HPLC-GFAA. J. Chromatogr. Sci. 19: 583;

1981.

Koch, G. H. ; Bursle, A. J. ; Liu, R. ; Pugh, E. N. A comparison of

gaseous hydrogen embrittlement, slow strain rate hydrogen embrittlement, and stress-corrosion cracking in Ti-8Al-TM0-lV. Metall. Trans. A

12: 1833; 1981.

Kruger, J. Dissolution of passive films on iron in nearly neutral

solutions. Proceedings symposium honoring 75th birthday of H. H. Uhl i g.

J. Electrochem. Soc. 81(8): 66; 1981.

Kruger, J. Corrosion principles and surface modification, chapter 6

in Surface treatments for improved performance and properties.

Burke, J. J. ; Weiss, V. , eds. New York, NY: Plenum Press; 1981. p. 93.

Morris, M. C. ; McMurdie, H. F. ; Evans, E. H. ; Paretzkin, B. P.

Panagiotopoulos , N. C. ; Parker, H. S. ; Hubbard, C. R. Standard x-ray

diffraction powder patterns. Nat. Bur. Stand. (U.S.) Monogr. 25; 1981

October, p. 105.

Munro, R. G. Criteria for choosing a linearized least squares technique for the exponential model exp (A x + A2 x). J. Comput. Phys. 44:

1981.

Ogburn, F. Electrodeposition research under Dr. William Blum. Nat.

Bur. Stand. (U.S.) Spec. Publ . 867; 1981. p. 185.

Olson, G. J. ; Dockins, W. S. ; McFeters, G. A.; Iverson W. P. Sulfatereducing and methanogenic bacteria from deep aquifiers in Montana.

Geomicrobiol . J. 2: 327; 1981.

Parks, E. J. ; Brinckman, F. E. ; Mullin, C. E. ; Anderson, D. A.;

Castelli, V. J. Characterization by tin-specific size exclusion

chromatography of the free radical copolymerization of tributyl tin

methacrylate and methyl methacrylate. J. Appl. Polym. Sci. 26: 2967;

1981.

Parks, E. J. ; Brinckman, F. E. Characterization of bioactive organotin polymers: fractionation and determination of MW by SEC-GFAA,

chapter in Controlled release of pesticides and pharmaceuticals.

Lewis, D. H. , ed. New York, NY: Plenum Press; 1981. p. 219.

Robbins, C. R. ; Mauer, F. A. Chemical degradation of castable refractories in coal gasification process environments. J. Mater. Energy

Syst. 3: 32; 1981.

Sanders, D. M. ; Wilke, M. E. ; Hurwitz, S. A.; Haller, W. K. The role

of water vapor and sulfur compounds on sodium vaporization during glass

melting. J. Am. Ceram. Soc. 64: 399; 1981.

561-157
Schenck, P. K. ; Travis, J. C. ; Turke, G. C. ; O'Haver, T. C. The collection of ions produced by laser-enhanced ionization in a hydrogen/

air flame. J. Phys. Chem. 85: 2547; 1981.

Weiss, C. S. ; Jewett, K. L. ; Brinckman, F. E. ; Fish, R. H. Applications of molecular substituent parameters for the speciation of

trace organometals in process fluids by element-specific HPLC.

Brinckman, F. E. ; Fish, R. H. , eds. Proceedings of the DOE/NBS workshop

on environmental speciation and monitoring needs for trace metal

containing substances from energy-related processes; 1981 May 18-20;

Gaithersburg, MD. Nat. Bur. Stand. (U.S.) Spec. Publ. 618; 1981

November, p. 187.

Wever, M. J. ; Myers, J. D. ; Blackburn, D. H. Optical properties of

Nd

3+

in tellurite and phospho-tel 1 uri te glasses. J. Appl. Phys. 52:

2944; 1981.

White, G. S. ; Feldman, A. Diffraction from a shallow rectangular

groove. J. Appl. Opt. 20: 2585; 1981.

Wolynec, S. ; Escalante, E. Relation between corrosion potential and

corrosion rate of steel in NaCl stagnant solutions. Proceedings of

the 8th international congress on metallic corrosion; 1981; Mainz,

West Germany; 1981. p. 99.

Chakrapani , D. G. ; Koch, G. H. ; Pugh, E. N. On the mechanism of SCC

in a Mg-Al alloy. Proceedings of the 6th international congress on metallic corrosion; 1975; Sydney, Australia. Austral. Corro. Soc.

Publ.; 1982. p. 387.

Clark, D. B. ; Weeks, S. J. ; Hsu, S. M. Chemiluminescence of fuels

and 1 ubricants--a critical review. ASLE Preprint #82-AM-5A-l; 1982.

Cronin, D. J. ; Blackburn, D. H. ; Haller, W. K. Unusual luminescence

behavior of terbium phosphate glasses. Nature 295: 680; 1982.

Cronin, D. J. ; Blackburn, D. H. ; Haller, W. K. Glass as material for

asbestos standards. Small, J. ; Steel, E. , eds. Proceedings of the

NBS/EPA asbestos standards workshop on asbestos standards: material

and analytical methods; 1980 October 1-3; Gaithersburg, MD. Nat. Bur.

Stand. (U.S.) Spec. Publ. 619; 1982. p. 21.

Dragoo, A. L. ; Domingues, L. P. Preparation of high-density ceria-yttria

ceramics. J. Am. Ceram. Soc. 65: 253; 1982.

Escalante, E. ; Bertocci , U. ; Mullen, J. L. ; Cohen, M. I.; Kruger, J. Development of i_n situ techniques for the detection of corrosion of

copper concentric neutrals of electric cables in underground environments. IEEE Trans. Powder Appar. Syst. PAS-101: 2061; 1982.

Feldman, A.; Waxier, R. M. Dispersion of the piezobirefringence of

GaAs due to strain-dependent lattice effects. J. Appl. Phys. 53:

1477; 1982.

561-158
Fish, R. J. ; Brinckman, F. E. ; Jewett, K. L. Fingerprinting inorganic

arsenic and organoarsenic compounds in in situ oil shale process

waters using a liquid chromatograph coupled with an atomic absorption

spectrometer as a detector. Environ. Sci. Technol. 16: 174; 1982.

Gates, R. S. ; Hsu, S. M. Development of a four-ball wear test procedure to evaluate automotive lubricating oils. ASLE Preprint #82-AM-64-A;

1982.

Grabner, L. H. ; Hastie, J. W. Flame boundary layer effects in lineof-sight optical measurements. Combust. Flame 44: 15; 1982.

Hardman, V. K. Magnetic and structural properties of Th6 Mn23 Dx and

Y6 Mn 23 Dx, chapter in The rare earths in modern science and technology,

Vol . III. New York, NY: Plenum Press; 1982. p. 477.

Hardman, V. K. ; Rhyne, J. J. ; Malik, S. ; Wallace, W. E. Site magnetization of cubic and hexagonal HoMn2

. J. Appl. Phys. 53: 1944; 1982.

Hastie, J. W. ; Plante, E. R. ; Bonnell, D. W. Alkali vapor transport

in coal conversion and combustion systems, chapter in Metal bonding

and interactions in high temperature systems with emphasis on alkali

metals. Gole, L. W. ; Stwalley, C. W. , eds. American Ceramic Society

Symp. Ser. 179; 1982. p. 543.

Jackson, J. A.; Blair, W. R. ; Brinckman, F. E. ; Iverson, W. P. Gas

chromatographic speciation of methyl stannanes in the Chesapeake Bay

using purge and trap sampling with a tin-selective detector. Environ.

Sci. Technol. 16: 110; 1982.

Kruger, J. Passivity and breakdown of passivity, chapter in Electrochemistry in industry-new directions. New York, NY: Plenum Press;

1982. p. 317.

Lashmore, D. S. ; Weinroth, J. F. Electrodeposition of metallic glass

alloys. Plat. Surf. Finish. 69: 8; 1982.

Munro, R. G. Reliability of partial structure factors determined by

anomalous dispersion of x-rays. Phys. Rev. B: Condens. Matter 25:

5037; 1982.

Ritter, J. S. ; Rodriguez, M. J. Corrosion phenomena for iron covered

with a cellulose nitrate coating. Corrosion 38: 223; 1982.

Roth, R. S. Classification of perovskite and other AB0 3 -type compounds.

Curr. Contents (Citation Classics) 22: 18; 1982.

Ruff, A. W. ; Lashmore, D. S. Dry sliding wear studies of nickelphosphorus and chromium coatings on 0-2 tool steel in selection and

use of wear tests for coatings, Am. Soc. Testing Mater. Spec. Tech.

Publ. 769; 1982. p. 134.

Santoro, A.; Roth, R. S. ; Austin, M. Powder neutron diffraction study

of stoichiometric LiTaOo and defective 9LiTa03 *Ta 2 0r . Acta Crystal logr.

Sect. B 38: 1094; 1982.

561-159
Schenck, P. K. ; Travis, J. C. ; Turke, G. C. ; O'Haver, T. C. Laser

enhanced ionization flame velocimeter. Appl. Spectrosc. 36: 168; 1982.

Schneider, S. J. ; Negas, T. ; Frederikse, H. P. R. An assessment of

materials requirements and research needs for open cycle magnetohydrodynamic (MHD) systems. Pure Appl. Chem. 54: 1325; 1982.

Thayer, J. S. ; Brinckman, F. E. The biological methylation of metals

and metalloids, chapter in Advances in organometal 1 ic chemistry,

Vol. 20. Stone, G. A.; West, R. , eds. New York, NY: Academic Press;

1982. p. 313.

Wenzel, J. T. ; Sanders, D. M. Sodium and boron vaporization from a boric oxide and borosilicate glass melt. Phys. Chem. Glasses 23: 47;

1982.

Wilson, W. K. ; Parks, E. J. Comparison of accelerated aging of book

papers in 1937 with 36 years natural aging. Restaurator 4: 1; 1982.

Becker, D. A.; Hsu, S. M. Tentative recommended tests for re-refined

base oil consistency. Proceedings of the conference on measurements

and standards, Nat. Bur. Stand.; 1982 September 14-16; Gaithersburg, MD.

Nat. Bur. Stand.; in press.

Beggs, D. V.; Hahn, M. T. ; Pugh, E. N. Recent observation on the

propagation of stress-corrosion cracks and their relevance to proposed

mechanisms of SCC. Proceedings of the honorary A. R. Troiano symposium

on hydrogen embrittlement and stress-corrosion cracking; 1980 June;

Cleveland, OH. Western Reserve University Publ.; in press.

Blair, W. R. ; Olson, G. J. ; Brinckman, F. E. ; Iverson, W. P. Uptake

and fate of tri-n-butyltin cation in estuarine bacteria. Microb. Ecol.;

in press.

Block, S. ; Piermarini, G. J. High pressure crystallography. Hist, of

Crystal logr. ; 1982; in press.

Bond, T. L. ; Yeske, R. A.; Pugh, E. N. Studies of stress-corrosion

crack growth in Al-Zn-Mg alloys using the double torsion method. Proceedings Am. Soc. Testing & Mater. Symp. on Environment-sensitive

fracture: evaluation and comparison of test methods; 1982 April; ASTM

Spec. Tech. Publ.; in press.

Bonnell, D. W. ; Valerga, A. J. ; Margrave, J. L. Radiation and conduction loss corrections to free drop calorimetry data. High Temp. Sci .

;

in press.

Brinckman, F. E. ; Jackson, J. A.; Blair, W. R. ; Olson, G. J.

;

Iverson, W. P. Ultratrace speciation and biogenesis of methyltin

transport species in estuarine waters, chapter in Trace metals in sea water, Wond, C. S. , ed. New York, NY: Plenum Press; in press.

561-160
Brinckman, F. E. ; Olson, G. J. ; Iverson, W. P. The production and

fate of volatile molecular species in the environment: metals and

metalloids, chapter in Atmospheric chemistry, Goldberg, E. D.

Konferenzen, D. , eds. , Berlin, West Germany: Springer-Verlag; in press.

Brinckman, F. E. ; Weiss, C. W. ; Fish, R. H. Speciation of inorganic

arsenic and organoarsenic compounds in fossil fuel products and precursors, chapter in Chemical and geochemical aspects of fossil energy

extraction, Yen, T. F. , ed. Ann Arbor, MI: Ann Arbor Science Publications; in press.

Cava, R. J. ; Roth, R. S. The structure of LaTa0 4 at 300 °C by neutron

powder profile analysis. J. Solid State Chem. ; in press.

Cava, R. J. ; Roth, R. S. ; Negas, T. ; Parker, H. S. ; Minor,. D. B. Crystal chemistry, modulated structure, and electrical conductivity

in the oxygen excess scheel ite-based compounds La, Th NbCL /? and

LaNb, W 0. . /0 . J. Solid State Chem.; in press.

x 1-x x 4+X/2 ’ K

Cava, R. J. ; Santoro, A. ; Murphy, D. W. ; Zahurak, S. ; Roth, R. S. The

structures of lithium inserted metal oxides: LiRe0 3 and Li 2 Re0 3 . J. Solid State Chem.; in press.

Comeford, J. J. ; Hsu, S. M. Ashing methods as low level metal contaminant indicators for re-refined basestocks. Proceedings of the conference on measurements and standards; 1982 September 14-16; Gaithersburg

MD. Nat. Bur. Stand.; in press.

Cook, L. P. SEM and TEM investigation of sintering in anorthite.

Proceedings of The Metallurgical Society-American Institute of Metallurgical Engineers/American Ceramic Society symposium on powder

processing; 1982 October; Louisville, KY; in press.

Cook, L. P. Powder processing of potassium aluminosilicates. The

Metallurgical Society-American Institute of Metallurgical Engineers

conference series proceedings; 1981 October, Louisville, KY; in press.

Coyle, T. D. Silica (Introduction), chapter in Kirk-Othmer encyclopedia of chemical technology, 3rd. Ed.; 1981; in press.

Cronin, D. J. ; Kingston, H. M. ; Liggett, W. S. ; Epstein, M. S. An

examination of the MCC-1 leach test method: comparison of glass com- positions. Proceedings of the 2nd annual conference on leaching mechanisms; 1981; Richland, WA; in press.

Cummings, A. L. ; Clark, D. B. ; Hsu, S. M. Evaluation of automotive

crankcase lubricants by differential scanning calorimetry. J. Automot.

Eng. ; in press.

Cummings, A. L. ; Hsu, S. M. Differential scanning calorimetry method

for oxidation stability of engine oils. Proceedings of the conference

on measurement and standards, 1982 September 14-16; Gaithersburg, MD.

Nat. Bur. Stand.; in press.

561-161
Cummings, J. J. ; Pei, P. T. ; Hsu, S. M. Comments on test methods for

chemical characterization. Proceedings of the conference on measurements and standards; 1982 September 14-16; Gaithersburg, MD. Nat.

Bur. Stand. ; i n press.

Dragoo, A. L. ; Chiang, C. K. ; Franklin, A. D. ; Bethin, J. R. A grain

boundary in yttria-stabi 1 ized zirconia. Proceedings of the 2nd American

Ceramic Society symposium, grain boundaries and interfaces in ceramics;

in press.

Dragoo, A. L. ; Chiang, C. K. ; Franklin, A. D. ; Bethin, J. R. Impedance

spectrum of a single grain boundary in yttria-stabilized zirconia.

Solid State Ionics; in press.

Escalante, E. Underground corrosion. Corrosion and the building

industry; NACE Publication; in press.

Farabaugh, E. N. ; Sanders, D. M. ; Wilke, M. E. ; Hurwitz, S. A.;

Haller, W. K. Preparation of thin amorphous films by E-beam evaporation

from multiple sources. Proceedings of the 13th annual symposium of

optical materials for high power lasers; 1982 November 16-20; Boulder, CO;

in press.

Feldman, A.; Dodge, M. J. ; Horowitz, D. ; Waxier, R. M. The NBS optical

measurements program: refractive index, thermo-optic constants, and

photoelastic constants. Proceedings of the 10th symposium on laser

damage; in press.

Feldman, A.; Farabaugh, E. N. ; Index, thickness, and birefringence of

thin films by guided waves. Proceedings of the 13th annual symposium

of optical materials for high power lasers, 1981 November 16-20;

Boulder, CO; in press.

Feldman, A.; Vorburger, T. A comparison of optical and mechanical

methods of thickness measurement. SPIE--Physical properties of optical

materials; in press.

Fiori, C. E. ; Blackburn, D. H. Low Z glass standards for biological

x-ray microanalysis. J. Microsc.; in press.

Foster, M. C. ; Hagins, W. A.; Blackburn, D. H. Energy dispersive

x-ray microanalysis of biological specimens. J. Analy. Chem. ; in press.

Fujishiro, I.; Piermarini, G. J. ; Block, S. ; Munro, R. G. Viscosities

and glass transition pressures in the methanol -ethanol -water system.

Proceedings of the 8th AIRAPT conference; 1982; Uppsala, Sweden, in

press.

Gates, R. S. ; Hsu, S. M. Development of an oxidation-wear coupled

test for the valuation of lubricants. J. Am. Soc. Lubr. Eng. ; in press.

Gates, R. S. ; Hsu, S. M. Development of a step-loading seizure test

for engine oil additive response. Proceedings of the conference on measurements and standards, 1982 September 14-16; Gaithersburg, MD.

Nat. Bur. Stand.; in press.

561-162
Grabner, L. H. ; Hastie, J. W. Equivalence of intertial force and

static buoyant force for flames. Combust. Flame; in press.

Hancock, D. K. ; Velapoldi, R. A.; DeVoe, J. R. ; Blackburn, D. H. Inorganic ion-doped glass beads as microspectrafluorimetric standards.

Proceedings of the 1982 Pittsburgh conference and exposition of analytical chemistry and applied spectroscopy; 1982 March 8-13; Atlantic

City, NJ; in press.

Hastie, J. W. ; Bonnell, D. W. Transpiration mass spectrometry: a new thermochemical cool, chapter in Thermochemistry today and its role in

the immediate future. Bieriro de Silva, M. A. V. , ed. Boston, MA:

Reidel Publications; in press.

Hastie, J. W. ; Horton, W. S. ; Plante, E. R. ; Bonnell, D. W. Thermodynamic models of alkali vapor transport in silicate systems. High Temp.

High Pressure; in press.

Hastie, J. W. : Plante, E. R. Mass spectrometric studies of MHD seedslag thermochemistry. Proceedings of the specialists meeting on coal

fired MHD powder generation; 1982 November; Sydney, Australia; in press.

Hodeau, J. L. ; Marezio, M. ; Santoro, A.; Roth, R. S. Neutron profile

refinement of the structures of Li 2 Sn03 and Li 2 Zr03

. J. Solid State

Chem. ; i n press.

Hsu, S. M. Lubricants, chapter in Encyclopedia of materials science

and engineering. Bever, M. , ed. New York, NY: Pergamon Press; in press.

Hsu, S. M. ; Becker, D. A. Characterization of re-refined lubricating

base oils. J. Automot. Eng.; in press.

Hsu, S. M. ; Ku, C. S. ; Lin, R. S. Relationship between lubricating

basestock composition and additive response in oxidation stability.

J. Automot. Eng.; in press.

Hubbard, C. R. Fluorophlogopite-low 26/large d-spacing powder diffraction Standard Reference Materials 675. J. Appl. Crystal! ogr. ; in press.

Hubbard, C. R. Certification of Si powder Standard Reference Material

640a. J. Appl. Crystal 1 ogr. ; in press.

Iverson, W. P. Microbial corrosion, chapter in Encyclopedia of materials

science and engineering. Bever, M. , ed. New York, NY: Pergamon Press;

in press.

Jewett, K. L. ; Brinckman, F. E. The use of element-specific detectors

coupled with high performance liquid chromatographs, chapter in Detectors in liquid chromatography, Vickrey, T. M. , ed. New York, NY:

Marcell Dekker Publishing Company; in press.

Kingston, H. M. ; Cronin, D. J. ; Epstein, M. S. Evaluation of a precise

static leach test for testing simulated nuclear waste, Analy. Chem.;

in press.

561-163
Kingston, H. M. ; Cronin, C. J. An examination of the MCC-1 leach test

method: experimental technique. Proceedings of the 2nd annual confer- ence on leaching mechanisms; Richland, WA; in press.

Kruger, J. Applications of equilibrium diagrams to corrosion and electrodeposition. Special proceedings on applications of equilibrium

diagrams, New York, NY: Plenum Press; in press.

Kruger, J. ; Rhyne, K. A. Current understanding of pitting and crevice

corrosion and its application to test methods for determining the

corrosion susceptibility of nuclear waste containers. Nucl. and Chem.

Waste Mgmt. ; in press.

Ku, C. S. ; Hsu, S. M. A thin-film oxygen uptake test for the evaluation of automotive lubricants. J. Am. Soc. Lubr. Eng.; in press.

Ku, C. S. ; Hsu, S. M. Thin film oxidation test: method devleopment

for engine oils. Proceedings of the conference on measurements and

standards; 1982 September 14-16; Gaithersburg, MD. Nat. Bur. Stand.;

in press.

Ku, C. S. ; Pei, P. T. ; Hsu, S. M. Evaluation of the ASTM D-2007

method for determination of lube base oil composition. Proceedings

of the conference on measurements and standards; 1982 September 14-16;

Gaithersburg, MD. Nat. Bur. Stand. ; in press.

Lashmore, D. S. Immersion deposition on aluminum. Proceedings of the

Aluminum Association finishing seminar; 1982 March 30; St. Louis, MO;

in press.

Munro, R. G. ; Block, S. ; Mauer, F. A.; Piermarini, G. J. Isothermal

equations of state for H 2 0-VII and D 2 0-VII. J. Appl. Phys. ; in press.

Munro, R. G. ; Block, S. ; Mauer, F. A.; Piermarini, G. J. Radial

distribution studies in a diamond anvil pressure cell. J. Appl. Phys.;

in press.

Negas, T. ; Amren, R. D. ; Domingues, L. P. ; Phillippi, R. M.

;

Drzewiecki, T. M. Fabrication of ceramic fluidic capillary temperature

sensors. J. Am. Ceram. Soc. Commun. ; in press.

Negas, T. ; Parker, H. S. ; Phillippi, R. M. ; Drzewiecki, T. M.

;

Domingues, L. P. Fabrication, testing, and evaluation of prototype

fluidic capillary pyrometer systems. Trans. J. Am. Soc. Mech. Eng.;

in press.

Ogburn, F. ; Clegg, E. T. Plating standards and specifications,

chapter 7, 3rd. Ed., Electroplating engineering handbook; in press.

Olsen, A.; Roth, R. S. Electron microscopy study of some synthetic

hollandite crystals. J. Solid State Chem.; in press.

Olsen, A.; Roth, R. S. Modulated structures in La-, Th Nb0.

+ and

LaNb.. W 0„^ /0 . J. Solid State Chem.; in press. 1-x x 4+x/2 ’ v

561-164
Olsen, A.; Roth, R. S. Crystal structure model of BaNd2 Ti 3 0 lo from

high resolution electron microscopy. J. Solid State Chem. ; in press.

Olson, G. J. ; Iverson, W. P. ; Brinckman, F. E. Bioalkylation, Subsection 15.8.3.3 in Inorganic reactions and methods, Zuckerman, J. J. , ed.

Verlag Chemie; in press.

Olson, G. J. ; Iverson, W. P. ; Brinckman, F. E. Biodeterioration potential of standard reference materials (SRMs). Proceedings of the 5th

international biodeterioration symposium; in press.

Olson, G. J. ; Rubinstein, J. ; Silver, S. Mercuric reductase enzyme

from a mercury-volatilizing strain of Thi obaci 1 1 us ferrooxi dans . J. Bacteriol.; in press.

Pei, P. T. ; Britton, Jr., J. H. ; Hsu, S. M. Hydrocarbon type separation of lubricating base oils in multi gram quantity by preparative

HPLC. J. Liq. Chromatogr. ; in press.

Pei, P. T. ; Fleming, R. F. ; Hsu, S. M. Test methods for total chlorine

in base oils. Proceedings of the conference on measurements and

standards; 1982 September 14-16; Gaithersburg, MD. Nat. Bur. Stand.;

in press.

Pei, P. T. , Hsu, S. M. Lube base oil characterization using liquid

chromatographic techniques. Proceedings of the conference on measurements and standards, 1982 September 14-16; Gaithersburg, MD. Nat.

Bur. Stand. ; in press.

Phillippi, R. M. ; Drzewiecki, T. M. ; Negas, T. ; Parker, H. S. Design

of a fluidic capillary pyrometer for contact duty at temperatures to

2750 °C. Proceedings of the 6th symposium on temperature, its

measurement and control in science and industry; 1982 June; in press.

Plante, E. R. ; Negas, T. ; Olson, C. J. Vaporization thermodynamics

of K2 S0 4

. High Temp. Sci.; in press.

Pugh, E. N. On the propagation of transgranular stress-corrosion

cracks. Proceedings of the NATO Advanced Research Institute on atomistics of fracture; 1982 May; Corsica; in press.

Ritter, J. R. ; Kruger, J. A new technique to study corrosion mechanisms under organic coatings. Proceedings of the 8th international

conference on organic coatings science and technology; 1982 July 12-16;

Athens, Greece; in press.

Ritter, J. J. ; Kruger, J. A new el 1 ipsometric-electrochemical approach

to the study of corrosion under organic coatings. Preprint of symposium

on advances in coating-metals corrosion protection, division of polymer

chemistry; 1982; M^inz, Federal Republic of Germany. American Chemical

Society; in press.

561-165
Ritter, J. R. ; Kruger, J. Studies on the subcoating environment of

coated iron using qualitative el 1 ipsometric and electrochemical techniques. Proceedings of the international conference on corrosion

control by organic coatings; 1981; Leidheiser, Jr., H. , ed.

Houston, TX: NACE; in press.

Robbins, C. R. ; Domalski, E. ; Kelly, R. X-ray analysis of selected RDF

and coal samples as a function of temperature. Resour. Recovery

Conserv. ; i n press.

Robbins, C. R. ; Hasselriis, F. Characterization of slag and fouling

residues from co-combustion of powdered refuse-derived fuel with

residual oil and comparison with coal and RDF residues, chapter in

Resource recovery from municipal, hazardous, and coal solid wastes.

New York, NY: Plenum Press; in press.

Sanders, D. M. ; Farabaugh, E. N. ; Haller, W. K. Glassy optical coating

by multisource evaporation. SPIE-Physical properties of optical materials; in press.

Santoro, A. ; Cava, R. J. ; Murphy, D. W. ; Roth, R. S. Use of the Pearson

Type VII distribution in the neutron profile refinement of the structure of LiRe0 3 and Le 2 Re0 3

. Acta Crystal logr. ; in press.

Scarff, C. J. ; Cronin, D. J. ; Wenzel, J. T. ; Kauffman, D. A. Viscositytemperature relationships at 1 atm in the system diopside-anorthite.

Am. Mineral.; in press.

Slattery, P. W. ; Smit, J. ; Pugh, E. N. Use of a load-pulsing technique

to determine stress-corrosion crack velocity. Proceedings of the

American Society for Testing and Material s--National Bureau of Standards

symposium on environment-sensitive fracture: evaluation and comparison

of test methods; 1982 April; Am. Soc. Testing Mater. Spec. Tech.

Publ . ; in press.

Walrafen, G. E. ; Abebe, B. ; Mauer, F. A.; Block, S. ; Piermarini, G. J.

;

Munro, R. G. Raman and x-ray investigation of ice-VII. Proceedings of

the 8th AIRAPT conference; 1982; Uppsala, Sweden; in press.

Weeks, S. J. ; Hsu, S. M. Comments of test methods for physical properties. Proceedings of the conference on measurements and standards;

1982 September 14-16; Gaithersburg, MD. Nat. Bur. Stand.; in press.

Weiss, C. S. ; Parks, E. J. ; Brinckman, F. E. Speciation of arsenic

in fossil fuels and their conversion process fluids, chapter in Arsenic:

industrial, biomedical, and environmental perspectives. Lederer, W. H.

;

Fensterheim, R. J. , eds. New York, NY: Van-Nostrand Reinhold; in press.

Wu, Y. C. ; Hsu, S. M. Lubricant degradation mechanisms for engine

oils. Proceedings of the conference on measurements and standards;

1982 September 14-16; Gaithersburg, MD. Nat. Bur. Stand.; in press.

561-166
Special Reports

Fernelius, W. C. ; Coyle, T. D. ; Powell, W. H. , eds. Nomenclature of

inorganic chemistry: II. 1—isotopically modified compounds. Pure and

Appl . Chem. 53: 1887; 1981.

Frederikse, H. P. R. ; Schenck, P. K. ; Burns, G. W. ; Dils, R. R.

Whetstone, J. Materials for instrumentation for fossil energy technologies. Nat. Bur. Stand. (U.S.) NBSIR 81-2348; Report to the

Department of Energy; 1981.

Haller, W. K. Problems with glass balcony enclosures. Letter report

to Architect of the Capitol; November 1981.

Hastie, J. W. ; Plante, E. R. ; Bonnell, D. W. Alkali vapor transport

in coal conversion and combustion systems. Nat. Bur. Stand. (U.S.)

NBSIR 81-2279; 1981.

Parks, E. J. ; Johannesen, R. B. ; Brinckman, F. E. Characterization of

organometal 1 ic polymers by chromatographic methods and nuclear magnetic

resonance. Nat. Bur. Stand. (U.S.) NBSIR 81-2424; Report to Naval

Ship Research and Development Center; 1981.

Sanderson, B. T. ; Kruger, J. Bibliography of literature on underground

corrosion of metals and alloys considered for use in the construction

of containers for nuclear waste. Nat. Bur. Stand. (U.S.) NBSIR 81-2409

Report to the Department of Energy; 1981.

Schneider, S. J. MHD material s--seed/slag interactions and effects.

Quarterly Report prepared for the Department of Energy; 1981.

Bonnell, D. W. Measurement of the high temperature thermodynamic

properties of tungsten liquid and solid. Manning, J. R. , ed. Nat.

Bur. Stand. (U.S.) NBSIR 82-2560; 1982.

Clark, D. B. ; Weeks, S. J. ; Hsu, S. M. An introduction to chemiluminescence methods for lubricant oxidation studies. Nat. Bur. Stand.

(U.S.) NBSIR 82-2490; Report to Office of Recycled Materials, NBS;

April 1982.

Fink, J. L. ; Escalante, E. ; Gerhold, W. F. Corrosion evaluation of

underground telephone cable shielding materials. Nat. Bur. Stand.

(U.S.) NBSIR 82-2509; Report to Rural Electrification Administration;

April 1982.

Schneider, S. J. ; Fuller, Jr., E. R. ; Fields, R. J. ; Chuang, T. J.

Krause, R. ; Dragoo, A.; Munro, R. G. Quarterly progress reports to

DOE sponsor for high temperature applications of structural ceramics.

September 1981, December 1981, March 1982, June 1982.

Schneider, S. J. ; Ondik, H. M. ; Christ, B. W. ; Perloff, A.; Tighe, N. J.

McDaniel, C. L. ; Wiederhorn, S. M. Quarterly progress reports to DOE

sponsor for materials research on the clean utilization of coal.

September 1981, December 1981, March 1982, June 1982.

561-167
Blair, W. R. Sampling, storage, and speciation of trace level organotin

compounds: experience in the laboratory and Rotterdam Harbor. Nat.

Bur. Stand. (U.S.) NBSIR 82-xxxx; Report to International Agricultural

Centre; in press.

DeVoe, J. R. ; Travis, J. C. ; Turk, G. C. ; Weeks, S. J. Laser enhanced

ionization in flames. Nat. Bur. Stand. (U.S.) NBSIR 82-xxxx; Report to

Environmental Protection Agency; in press.

Kruger, J. ; Rhyne, K. A.; Hardman, V. K. Current understanding of

pitting and crevice corrosion and its application to test methods for

determining the susceptibility to such corrosion of nuclear waste

metallic containers. Nat. Bur. Stand. (U.S.) NBSIR 82-xxxx; Report to

Department of Energy; in press.

Kruger, J. ; Ritter, J. J. ; Carroll, J. ; Melmed, A. J. Compilation of

several NBS reports for ONR. Nat. Bur. Stand. (U.S.) NBSIR 81-2396;

Report to Office of Naval Research; in press.

Olson, G. J. ; Weiss, C. S. ; Correa-Becker , R. ; Jackson, J. A.;

Brinckman, F. E. Recent advances in speciation of organometals and

detection of biodeterioration in SRMs. Nat. Bur. Stand. (U.S.)

NBSIR 82-xxxx; Report to NBS Office of Standard Reference Materials;

in press.

Parks, E. J. ; Johannesen, R. B. ; Brinckman, F. E. Characterization

of organometal 1 ic copolymers and copolymerization by size exclusion

chromatography coupled with metal- and mass-sensitive detectors.

Nat. Bur. Stand. (U.S.) NBSIR 82-xxxx; Report to U.S. Naval Ship

Research and Development Center; in press.

I Books

Brinckman, F. E. ; Fish, R. H. , eds. Environmental speciation and

monitoring needs for trace metal -containing substances from energyrelated processes, proceedings of the DOE/NBS workshop. 1981 May 18-20,

Gaithersburg, MD. Nat. Bur. Stand. (U.S.) Spec. Publ. 618; 1981

November; 324 pp.

Roth, R. S. ; Negas, T. ; Cook, L. P. Phase diagrams for ceramists, Vol. IV. Columbus, OH: American Ceramic Society; 1981.

Ondik, H. M. ; Christ, B. W. ; Perloff, A. Construction materials for

coal conversion—performance and properties data. Nat. Bur. Stand. (U.S.)

Spec. Publ . ; in press

Sponsored Conferences

Sixth Annual Conference on Materials for Coal Conversion and Utilization

Department of Energy, Electric Power Research Institute, Gas Research

Institute, and National Bureau of Standards

S. J. Schneider, Chairman

October 7-9, 1981

561-168
American Crystallographic Association

National Bureau of Standards/Smithsonian Institution

C. R. Hubbard and J. K. Stalick, Co-chairpersons

March 29- April 2, 1982

Symposium on Environment-Sensitive Fracture: Evaluation and

Comparison of Test Methods

American Society for Testing and Materials/National Bureau of Standards

E. Neville Pugh and G. M. Ugiansky, Co-chairmen

April 26-28, 1982

Gordon Research Conference on Corrosion

E. Neville Pugh, Chairman

July 26-30, 1982

Standard Reference Materials

SRM 640a - 20/D-spacing Standard for X-ray Diffraction

C. R. Hubbard, 1982

SRM 774 - Glass Dielectric Constant and Loss Characteristic

M. J. Cellarosi, 1982

External Recognition

G. J. Olson

Visiting Scientist, Department of Biology, Washington University,

St. Louis, MO

January 1982

F. E. Brinckman

Guest Worker, Lawrence Berkeley Laboratory, University of California,

Berkeley, CA

March 1982

C. S. Weiss

Guest Scientist, Department of Chemistry, Texas A & M University,

College Station, TX

April 1982

Patents

Fluidic Thermistor/Fugacity Device

T. Negas, L. P. Domingues, T. M. Drzewiecki, and R. M. Phillippi

Patent No. 4,264,423,

April 28, 1981

561-169
Industrial Interactions

1. INDUSTRIAL RESEARCH ASSOCIATES

Electrodeposition Group- -David S. Lashmore, Group Leader

• The Aluminum Association and American Electroplaters Society:

David Thomas--Research Associate, sponsor: David S. Lashmore.

The program is set up to investigate electrodeposition of

anodized aluminum.

Ceramic Sciences Group--Taki Negas, Group Leader

• Joint Committee for X-ray Powder Diffraction Standards (JCPDS)--

International Centre for Diffraction Data. Staff at NBS:

M. E. Morri s--Di rector , E. H. Evans, N. Pyros, Research Associate,

B. Paretzkin, H. F. McMurdie, H. S. Parker, D. Gladhill,

S. Lederman, C. Wingo; B. Snyder—consultant, Alfred Univ. , Dept. Ceramic Engineering, sponsor: C. R. Hubbard and T. Negas.

This non-profit corporation functions in cooperation with

the American Ceramic Society, the American Crystallographic

Association, the American Society for Testing and Materials,

the Clay Minerals Society, the Institute of Physics, the Mineralogical Society of America, the Mineralogical Society of

Great Britain and Ireland, the National Association of Corrosion Engineers, and the Societe Francaise de Mineralogie et

de Cristallographie. JCPDS produces the Powder Diffraction

File (PDF) which is a continuing compilation of diffraction

patterns gathered from numerous sources. Over 80 industries

in Fortune 500 and over 1200 other private, government, and

academic organizations purchase the data. NBS contributes new

or improved data to the PDF as well as XRD techniques and SRMs

especially applicable to the processing and quality control of

ceramic and metal alloy materials.

Chemical and Biodegradation Processes Group--Frederick E. Brinckman,

Group Leader

t Mobil Research and Development Corporation; Research Associate:

Thomas F. Degnan; NBS Sponsor: Frederick E. Brinckman--

molecular characterization and monitoring of arsenic catalyst

poisons in candidate processes for shale oi 1 s-measurement

technology.

Glass and Optical Materials Group--Wol fgang K. Haller, Group Leader

• Approximately 20 glass companies through ASTM; Sponsor Research

Associate: Dr. A. C. Siefert. NBS sponsors: G. A. Uriano

and M. J. Cellarosi. The program establishes priority listing

of SRMs of interest to glass industry and coordinates SRMmaterial procurements and work done outside of NBS.

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Tribochemistry Group—Stephen M. Hsu, Group Leader

• Chinese Petroleum Corporation; Ron Lin and S. M. Hsu. The

program characterizes lubricant composition with respect to

oxidation stability and wear-measurement technology.

2. OTHER INDUSTRIAL GUEST WORKERS AT CMS

High Temperature Processes Group-- John W. Hastie, Group Leader

• Robert J. Cava, Bell Labs, Murray Hill, NJ.

NBS sponsor: Robert S. Roth

This work deals with neutron diffraction of ionic conductivity

materials.

Ceramic Sciences Group—Taki Negas, Group Leader

• T. M. Drzewiecki, Systems Planning Corporation, V

NBS sponsor: T. Negas

The work of this program determines durability of ceramic

coatings on metals in molten metal (800-1550 °C) environments.

• L. P. Domingues, Research and Development Director, TransTech, Inc. , MD

NBS sponsor: T. Negas

The work deals with the characterization of ceramic powders,

green compacts, and densified microstructures for technical

ceramics.

3. ARCHIVAL TECHNICAL PAPERS CO-AUTHORED WITH INDUSTRIAL EMPLOYEE

Corrosion Group—Jerome Kruger, Group Leader

• "Studies of Hydrogen Embrittlement and Stress-corrosion Cracking

in an Aluminum-Zinc-Magnesium Alloy" by:

E. N. Pugh, NBS; S. W. Ciarialdi, Amoco; J. L. Nelson, INCO;

R. A. Yeske, Westinghouse , Hydroqen Effects in Metals, TMSAIME (1981), p. 437.

• "A Comparison of Gaseous Hydrogen Embrittlement, Slow-strainrate Hydrogen Embrittlement, and Stress-corrosion Cracking in

Ti-8Al-lMo-lV" by:

E. N. Pugh, NBS; G. H. Kock, Battelle; R. Liu, Bell Labs. Met.

Trans. A. , 12A, 1833 (1981).

• "On the Mechanism of SCC in Mg-Al Alloy" by:

E. N. Pugh, NBS; D. G. Chakrapahi , Mei-Charl ton, Inc. Proc.

6th Internat. Congress on Metallic Corrosion, in press.

• "Recent Observations on the Propagation of Stress-corrosion

Cracks and Their Relevance to Proposed Mechanisms of SCC" by:

E. N. Pugh, NBS; D. V. Beggs, Conoco. Proc. of A. R. Troiano

Honorary Symposium on Hydrogen Embrittlement and SCC, in press.

561-171
High Temperature Processes Group--John W. Hastie, Group Leader

• "The Structure of LaTa0 4 at 300 °C by Neutron Powder Profile

Analysis" by:

R. S. Roth, NBS; R. J. Cava, Bell Labs.

J. Solid State Chem. , 36 139 (1981)

• "Crystal Chemistry, Modulated Structure, and Electrical Conductivity in the Oxygen Excess Scheelite Based Compounds

La, Th NbO. . /0 and LaNb, W 0.^ , " by: 1-x x 4+x/2 1-x x 4+x/2 J

R. S. Roth, NBS; T. Negas, NBS, R. J. Cava, Bell Labs.;

H. S. Parker and D. B. Minor.

J. Solid State-Chem. , 40, 318 (1981)

• "Revised Th02 -Nb 2 0 5 Phase Diagram" by:

R. J. Cava, Bell Labs; R. S. Roth, NBS; D. B. Minor

J. Am. Ceram. Soc. Comm. 64, p. C64, April 1981

• "Structural Aspects of Lithium Insertion in Oxides: Li ReOand Li 2 FeV3 0 8

" by: x 6

R. J. Cava, Bell Labs; A. Santoro, D. W. Murphy, S. Zahurak,

and R. S. Roth, NBS.

Solid State Ionics 5, 323 (1981)

• "Use of the Pearson Type VII Distribution in the Neutron Profile Refinement of the Structures of LiRe0 3 and Li 2 Re03

" by:

A. Santoro, R. J. Cava, Bell Labs; D. W. Murphy and R. S. Roth,

NBS.

Acta Crystal logr. , in press

• "The Structures of Lithium Inserted Metal Oxides: LiRe0 3 and

Li 2 Re0 3

" by:

R. J. Cava, Bell Labs; A. Santoro, D. W. Murphy, S. Zahurak,

and R. S. Roth, NBS.

J. Solid State Chem., 42, 251 (1982)

• "FeNb 3 Se 10 : A New Structure Type Related to NbSe3

" by:

R. J. Cava, Bell Labs; V. L. Himes, A. D. Mighell, and R. S. Roth,

NBS.

Phys. Rev. B, 24, No. 6, Sept. 15, 1981.

Ceramic Sciences Group--Taki Negas, Group Leader

• "Design of Fluidic Capillary Pyrometer for Contact Duty at

Temperatures to 2750 °C", Symposium (VI) on Temperature, June

1982. T. Negas, NBS; T. M. Drzewiecki, Systems Planning

Corp. ; R. M. Phillippi, U.S. Army (guest worker with T. Negas).

• "Fabrication, Testing, and Evaluation of Prototype Fluidic

Capillary Pyrometer Systems", Journal of Dynamics Systems and

Control, ASME, December 1981. T. Negas, NBS; R. M. Phillippi,

U.S. Army; T. M. Drzewiecki, Systems Planning Corp.; L. P. Domingues,

Trans-Tech (guest worker with T. Negas).

• "Fabrication of Ceramic Fluidic Capillary Temperature Sensors"

(in press) by:

T. Negas, NBS; L. P. Domingues, Trans-Tech; R. D. Amren,

Trans-Tech; R. M. Phillippi, U.S. Army; T. M. Drzewiecki,

Systems Planning Corp.
• "Crystal Chemistry, Modulated Structure, and Electrical Conductivity in the Oxygen Excess Scheel ite-based Compounds

Lal-x

Th

xNb04+x/2 and LaNbl-xWx°4+x/2" (in P ress) ’ J - So1id

State Chem. , 40(3) December 1981. R. S. Roth, NBS; T. Negas,

NBS; R. J. Cava, Bell Labs.

• "Preparation of High-Density Ceria-Yttria Ceramics" by:

A. L. Dragoo, NBS; L. P. Domingues, Trans-Tech, J. Am. Ceram.

Soc. , 65(5) May 1982.

• "NBS Monograph 25-Section 18, Standard, X-ray Diffraction

Powder Patterns" U.S. Dept, of Commerce/NBS, October 1981

Section 19, October 1982, by:

C. R. Hubbard, NBS; JCPDS staff.

• "Characterization of Ash Residues From a Refuse-Derived Fuel/Oil

Combustion Study," ASTM Symposium on Alternative Fuels and

Future Fuel Specifications for Stationary Gas Turbine Applications, by:

C. R. Robbins, NBS; F. Hasselriis, Combustion Equipment Associates.

• "Characterization of Slag and Fouling Residues from Co-Combustion

of Powdered Refuse-Derived Fuel with Residual Oil and Comparison

with Coal and RDF Residues", accepted for publication, by:

C. R. Robbins, NBS; F. Hasselriis, Combustion Equipment Associates.

Tribochemistry Group—Stephen M. Hsu, Group Leader

• "Base Oil Composition Effects on Oxidation Stability," S. M. Hsu

and C. S. Ku, R. Lin, Chinese Petroleum Corporation.

4. FORMAL VISITS (FY81 through FY82)

Corrosion Group—Jerome Kruger, Group Leader

Visits to NBS

• Owens Corning, April 12, 1982—corrosion of metals protected

by coatings.

• INCO, July 6, 1982—stress-corrosion test methods.

• EPRI, December 5, 1980—underground corrosion of power cables.

• Battel le, October 24, 1980—approaches toward the estimation

of corrosion rates of nuclear waste cannisters.

• Texas Instruments, October 28, 1980—underground corrosion of

telephone cables.

t Texas Instruments, May 21, 1982—possibilities for establishing a corrosion data center at NBS.

• Concrete Pipe Association, February 19, 1982 —possibility of a CPA research associateship on corrosion of aluminum in soils.

0 Bethlehem Steel Corp. , January 16, 1981—piling corrosion.

0 U. S. Steel Corp., January 16, 1981--piling corrosion.

0 American Iron and Steel Inst., January 16, 1981--piling corrosion.

0 Cathodic Protection Consultants, March 11, 1981—corrosion in

concrete.

0 Florida Power and Light Co., April 22, 23, 1981--corrosion of

electric power cable.

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• Armstrong Products Co., May 27, 1981--protection of piling.

• Baltimore Gas and Electric, June 3, 1981—corrosion of concrete.

• U. S. Steel Corp. , June 26, 1981—corrosion of piling.

• Bethlehem Steel, November 4, 1981—corrosion of piling.

• U.S. Steel, November 4, 1981--corrosion of piling.

• Baltimore Gas and Electric, June 17, 1982--corrosion of electric power cable.

• Federated Metals (ASARCO), December 1, 1981—protection of

electric power cable.

Visits by NBS

• Electrical Power Research Inst. , April 29, 1981--corrosion of

electric power cable.

• Baltimore Gas and Electric Power, May 22, 1981--corrosion of

electric power cable.

• Charles R. Velzy Assoc., June 3, 1981—Corrosion in incinerators.

• MCP Facilities, Inc., September 25, 1981--protection of piling.

Electrodeposition Group—David S. Lashmore, Group Leader

Visits by NBS

• David Craig, Ford Motor Company, May 28, 1982 —wants our Group

to produce electrochemical type thickness standards.

• John Dueber, Degussa Corp. , American Electroplaters Society,

May 27, 1982--get acquainted with our work on plating nickel

chromium alloys.

• Takeyuki Fukuda, Nippon Steel Corp., June 1, 1982--i nformation

on our dye penetrant test SRMs.

t Richard Sard, Utillyte Chemical Corp., July 1982--information

on deposition of metallic glass alloys.

• Vasanth Kunigamalli, Goddard Space Flight Center, May 1982--

become acquainted with work done by Group, especially alloy

plating and black coatings.

• Yair Assaf, Bokak Electroplaters Co. LTD. , Israel--information

on pulsed electrodeposition.

• James McGuire, Pres., Applied Systems, Inc., McLean, VA.

,

January 1981—information on black electroless nickel for

night vision devices.

• Frank Brown, Eastman Kodak, May 1981—information on black

electroless nickel for technical group on radiometry.

• Members of ASTM Committee E-44 (Solar Conversion), March

1981-- information on black electroless nickel for solar energy

conversion applications.

• Members of ASTM Committee E-21 (Space Simulation), October

1981--i nformation on black electroless nickel for application

in space simulation.

• Fred Roselle, Westi nghouse , December 1981--information on black electroless nickel for application for image intensifies

in video cameras for night surviellance for industry and

mi 1 itary.

• John Caulfield, Arthur D. Little Co., June 1981--appl ications

for black electroless nickel for solar energy.

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• Ball Aerospace, Boulder, CO —recipients of patent rights for

black electroless nickel.

Chemical and Biodegradation Processes Group--Frederick E. Brinckman,

Group Leader

Visits to NBS

• A. Fetell and J. Reardon, E. I. DuPont and Nemours Company,

May 8, 1981--di scuss design and commercial production of

"tailored" organotin polymers meeting Navy service criteria as control led-rel ease marine anti fouling paints.

• Bernard Tramier, Societe National e Elf Aquitane, France,

June 18, 1982--measurement methodology for monitoring industrial organotin biocide uses and applications of FT-NMR to

i n situ characterization of heteroatomic molecules in petroleum

ref ini ng.

• J. Truella and C. Simpson, Mobil Research and Development

Corp. , July 22, 1982--appl ications of multi-nuclear FT-NMR to

syncrude processing measurements and use of element-specific

chromatographic detectors for refractory metal molecular

speciation in syncrude processing catalysts.

Visits by NBS

• F. E. Brinckman, M and T Chemicals, Inc., June 8, 1982—con- sult with senior management on measurement problems associated

with recent oyster kills in France and ban on organotin use

there.

• F. E. Brinckman and R. B. Johannesen, Rohm and Haas Co. and

Monsanto Chemical Co. , July 20, 1982 —at request of Navy sponsor consult with industrial contractors on current status of

measurement and production problems with large-scale procurement of fleet anti foul ant organotin polymers (at Naval Research Lab).

High Temperature Processes Group--John W. Hastie, Group Leader

Visits by NBS

• R. T. Frost, General Electric Space Laboratories, May 1982--

di scuss levitation calorimetry.

Ceramic Sciences Group—Taki Negas, Group Leader

Visits to NBS

• Nutan C. Bhiwandker, Hameed Khan and J. Bedgood, Ampex Corporation, CA, May 1982--tour facilities and discuss extrusion

of lithium ferrite wave guides.

• T. Gluckner and B. Cottage, Progressive Apparel, VA, July

1982--di scuss sintering of Si C and Si C composites (visited

once a week from July 1982 on).

• J. Shade, Battelle Pacific NW Labs., May 1982 —tour facilities

and discuss ceramic processing of nuclear waste.

561-175
• R. M. Arons, and 0. R. Hughes, Celanese Research Company,

April 1982--di scuss advances in ceramic powder processing for

potential marketing.

• J. Werth, Englehard Industries, November 1981--di scuss ceramic

coatings for fuel cell applications.

• Delegation from Carborundum Corp. (through S. J. Schneider)

discuss corrosion problems with ZrSi0 4 -based, fusion cast

ref ractori es.

• E. Demaray, Airco Temescal , April 1982--di scuss zirconia powders for turbine coatings.

• V. E. Haloulakos, McDonnell Douglas Astronautics Company, CA,

June 1982--discuss ceramic coatings for refractory metals.

• Delegation from Japanese Steel /Ceramics Industries —ceramic

sensors for temperature measurements.

• Corning Group (through J. B. Wachtman) —ceramic sensors and

fabrication.

• D. Harris, APS Materials, Inc., OH, September 1981—plasma

spray ceramic powders and technology, potential joint effort

with NBS and NASA.

• A. Morrell, Thomson-CSF, France, April 1982 —processing of

microwave ceramics.

• J. Skalny, Martin Marietta Labs, MD, June 1982--characterization and classification of coal ash.

Visits by NBS

• AiResearch Company, Garrett Corporation, CA, June 30, 1982--

industrial needs for ceramic research.

• Ampex Corp., CA, June 28, 1982--i ndustrial needs for ceramic

research.

• Rockwell International Science Center, CA, June 29, 1981--

i ndustrial needs for ceramic research.

• Martin Marietta Laboratories, MD, May 19, 1982--i ndustrial

needs for ceramic research.

• Harbi son-Wal ker Refractories, Co., PA, June 2, 1982--industrial needs for ceramic research.

• PPG Industires, PA, June 2, 1982 — industrial needs for ceramic

research.

• Alcoa Technical Center, PA, June 3, 1982--i ndustrial needs for

ceramic research.

• Westinghouse Research and Development Center, PA, June 4,

1982--industrial needs for ceramic research.

• Walmet Division, GTE--i ndustrial needs for ceramic research in

cemented carbides.

Glass and Optical Materials Group--Wol fgang K. Haller, Group Leader

Visits to NBS

• Ai rco-Temescal , Fall 1981--zi rconi a films-glassy film evaporation work.

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• Balzers, May 1982--NBS glassy film process.

• Optical Coatings Lab (OCLI), Fall 1981--NBS glassy film process.

• Sperry-Rand UNIVAC, February 1982--metal 1 ized glass fibers for

electronic circuit-boards.

• Brockway Glass Co. , February 1982 —NBS glass melt evaporation

work.

• Dentsply International, Fall 1981--fl uorescence in artificial

teeth.

• COMSAT, several times--structure of silica.

• Shell Development Corp. , Fall 1981--coal slag viscosity.

• Tracor, Winter 1981/82--optical properties for fiber optic

material

• Owens-Corning Fiberglas, December 1981--fiberglass reinforced

Portland cement materials.

• Owens-Corning Fiberglas, Fall 1981--glass evaporization studies

of NBS.

Visits by NBS

• Martin Marietta--to assess industrial needs in glass.

• Ampex Corporation—to assess industrial needs in glass.

0 Hoya-USA--to assess industrial needs in glass.

Tribochemistry Group--Stephen M. Hsu, Group Leader

Visits to NBS

# Geo Centers Inc., November 5, 1980--to characterize of deuterated hydrocarbons.

0 Mobil Research and Development, November 10, 1980—to plan for

the NBS/ASTM cooperative study.

0 Idenmitsui Oil Company, January 16, 1981-- friction and wear

test methods.

0 Mobil Oil, January 16, 1981--base oil characterization methods.

0 Texaco, January 21, 1981--characterization of lubricating base

oils.

0 Amoco, February 4, 1981--Amoco-NBS cooperation on bench test

development.

0 Mobil, July 20, 1981--base oil consistency program.

0 Amoco, January 21, 1982--oxygen uptake test methodology.

0 Mobil, January 15, 1982--Tribol ogy programs at NBS.

0 Chinese Petroleum Institute, March 10, 1982 —1 ubricant research.

0 Mobil, July 8, 1982--NBS-i ndustry cooperative study program

planning.

0 Lubrizol, July 8, 1982--NBS-industry cooperative study program

planning.

0 Shell (Canada), July 8, 1982--NBS-industry cooperative study

program planning.

0 Gulf, July 8, 1982 —NBS-industry cooperative study program

planning.

0 Exxon, July 8, 1982--NBS-i ndustry cooperative study program

planning.

0 Paramins, July 8, 1982--NBS-i ndustry cooperative study program

pi anni ng.

0 Imperial Oil (Canada), July 8, 1982--NBS-industry cooperative

study program planning.

561-177
• C i by Geigy, July 8, 1982--NBS- industry cooperative study

program planning.

• Sun Oil, July 8, 1982--NBS-industry cooperative study program

planning.

Visits by NBS

• Gulf Oil, October 13, 1980—talk on research needs in lubrication.

• Gulf Oil, October 30-31, 1980--1* nformation exchange on various

technical projects.

• Imperial Oil, September 16, 17, 1981--di scuss various technical

topics in base oil characterization research and agreed to

cooperate.

• API, February 4, 1982 —discuss mutual interest in petroleum

research.

• Lubrizol, August 26, 1982--di scuss technical information

exchange and possible cooperative programs.

5. PARTICIPATION IN MEASUREMENT PROGRAMS

Corrosion Group--Jerome Kruger, Group Leader

• ASTM G01. 06. 02--Stress Corrosion Test Environment, round robin

on chloride stress corrosion cracking.

• ASTM G01. 10--Corrosi on in Soils, round robin on corrosion

measurements in soils.

Electrodeposition Group—David S. Lashmore, Group Leader

• ASTM B08--round robin beta-backscatter (coating thickness

measurements).

Chemical and Biodegradation Processes Group--Frederick E. Brinckman,

Group Leader

• ASTM G-l--Corrosion of Metals, W. P. Iverson participated in

round robin test comparing electrochemical corrosion measurement methods.

High Temperature Processes Group--John W. Hastie, Group Leader

• DuPont Savannah River Laboratory-vaporization of simulated

nuclear waste glass materials, DuPont prepares samples and

provides applied data from pilot plant experience and we provide high precision basic data on vaporization rates needed

for optimizing plant conditions for minimization of vaporization losses.

• DOE-Morgantown , G.E., Westi nghouse , and other gas turbine and

air pollution control companies —collaborative program, participants provide pilot plant experiences and manufacture

alkali emission control devices, we provide basic thermochemical data on alkali vapor transport from materials present in

combustor such as coal ash/slag, dolomite, and glass or ceramic

alkali absorbants.

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• NBS, GE, Rice Univeristy (NASA support) —joint program, ex- periment on levitation calorimetry of liquid tungsten, experiments designed by us and carried out at GE, King of Prussia,

PA laboratories.

Ceramic Sciences Group—Taki Negas, Group Leader

• Exxon Production Research Co., Texas--round robin, "Comparison

of Mineral Constituents in a Sample From Herrin (No. 6) Coal

Member From Illinois," to be published in a USGS Survey Circular (~ 1983), Dr. R. B. Finkelman, editor.

Glass and Optical Measurements Group—Wolfgang K. Haller, Group Leader

• ASTM--round robins and interlaboratory testing programs on

(a) Electrical high temperature resistivity of glass melts,

(b) Dielectric constant of glass (SRM), (c) Thermal expansion

of glass, (d) Analysis of high alumina sand, (e) Analysis of

ferrous/ferric ratio of glasses. Involves: Owens-Corni ng

Fiberglas, Owens-Illinois Glass Company, Anchor Hocking Glass

Company, Johns-Manville Company, Corning Glass Company,

Brockway Glass Company, Ferro Corporation, General Electric,

PPG Industries, LOF Company, AFG Industries.

Tribochemistry Group—Stephen M. Hsu, Group Leader

• NBS/ASTM Basestock Consistency Program. The program involves

taking monthly production samples from 10 refineries (four

virgin oil refineries, six re-refineries) and the samples are measured by 14 participating labs for quality and consistency.

Each lab conducted different tests (about 40 tests on each

sample). Results were sent to NBS for analysis and compilation. Companies participating include: Mobil, Shell, Lubrizol,

Gulf, Chevron, Filmite Oil, Motor Oil Refining Company, Savant,

Texaco, Sun.

• NBS sponsored base oil research program. This program aims' at

understanding the base oil compositional effects on oxidation

stability. Over 100 base oil samples from 14 different crude sources were collected. Each company also furnishes compositional and other analytical data on each sample. Companies

participating include: Lubrizol, Amoco, Shell (Canada), Gulf,

Chevron, Mobil, Exxon, Paramins, Imperial (Canada), Sun.

6. DATA PROGRAMS

Corrosion Group-- Jerome Kruger, Group Leader

• EPRI —research on underground corrosion of copper concentric

neutrals on power cables.

• AISI —corrosion data on corrosion of piling.

• AISI —corrosion data on underground corrosion of stainless

steels.

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High Temperature Processes Group—John W. Hastie, Group Leader

• American Ceramic Society Advisory Committee on Phase Equilibria Data Center--Lawrence P. Cook, chairman.

• American Ceramic Society, Development Committee, S. J. Schneider.

Ceramic Sciences Group—Taki Negas , Group Leader

• JCPDS—round robin, "Comparison of Mineral Constituents in a Sample From Herrin (No. 6) Coal Member From Illinois", to be

published in a USGS Survey Circular.

• Materials and Components for Fossil Energy Applications,

H. M. Ondik and A. Perloff, performance and property evaluated

data for ceramics, alloys, composites. Industrial contractors'

reports through DOE utilized predominately as data source. Publication of "Construction Materials for Coal Conversion"

anticipated in 1983.

Electrodepotision Group- -David S. Lashmore, Group Leader

• ASTM round robin on microhardness (B08).

• ASTM round robin on beta-backscatter instruments.

7. FORMAL ADVISORY ACTIVITIES

Corrosion Group—Jerome Kruger, Group Leader

• Metals Properties Counci 1 --Subcommi ttee and Task Group on Corrosion Fatigue Testing.

• EPRI--Corrosion Advisory Committee on Nuclear Reactors.

t Metals Properties Council —Subcommittee and Task Group on Corrosion of Metals in Association with Concrete.

Electrodeposition Group—David S. Lashmore, Group Leader

• National Materials Policy Board—David Lashmore is NBS representative on Flame Sprayed Coatings.

Chemical and Biodegradation Processes Group—Frederick E. Brinckman,

Group Leader

• Chemical Manufacturers Association—F. E. Brinckman organized

CMA-sponsored Symposium on Arsenic Production and Use, NBS,

November 4-6, 1981.

• International Tin Research Institute (U.K. ), F. E. Brinckman--

consul tations on development of organotin speciation standard

for industry.

t International Biodeterioration Research Group, U.S., W. P. Iverson

--surveyed current research in field, evaluated most important

industrial problems in field with recommendations for future

research.

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• International Nutritional Anemia Consultative Group--The Nutritional

Foundation, Inc., F. E. Brinckman—invited consultant on matters

dealing with measurements of bioavailability of iron and its

compounds commercially added to foodstuffs, food industry-wide

sponsorshop.

Ceramic Sciences Group—Taki Negas, Group Leader

• JCPDS Board of Directors, C. R. Hubbard, Vice-chairman and

technical coordinator at NBS.

• American Ceramic Society, T. Negas, L. P. Cook, and R. S. Roth--

Co-editors, Phase Diagrams for Ceramists.

• Materials Review Board (MRB), T. Negas--for data and procedures

related to nuclear waste materials and testing by the Materials

Characterization Center, Battel le NW; industry to utilize data

for encapsulation and disposal of nuclear wastes.

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FRACTURE AND DEFORMATION DIVISION (562)

Richard P. Reed, Chief

Sheldon M. Wiederhorn, Deputy Chief

C. Montgomery, Secretary

Structures and components must be mechanically reliable. A significantly

•large portion of our Nation's effort to ensure public safety and environmental quality concentrates on material and structural mechanical integrity.

Material fracture imposes a high cost on the national economy. Careful

design, structural codes and standards, material development and characterization, quality control and inspection, and the replacement, inconvenience, injuries, and deaths from unexpected failures all contribute to

this cost.

The Division has completed assessment of the costs of fracture to the

Nation. The results are being reported to the Subcommittees on Natural

Resources and Environment and on Science, Research, and Technology of

the House of Representatives Committee on Science and Technology. Even

with the use of the currently best available design, fabrication, and

inspection procedures, sometimes structures, mechanical components, and

containers fail during use. The economic consequences for the domestic

economy of unintended failures and the costs to prevent fracture have

been found to be large, of the order of 4 percent of the Gross National

Product. The economic benefits to be derived from wider application of

existing fracture-control technology have been determined. The economic

impact of generic research to improve understanding of fracture processes

and to control fracture have been estimated. Various research areas to

facilitate future cost reductions have been identified.

Division personnel are located in both Boulder and Gaithersburg. Although

separate geographically, these two groups complement each other. The

Boulder group emphasizes elastic-plastic fracture mechanics and lowtemperature properties in its study of metals, alloys, and composites.

The Gaithersburg group emphasizes time-dependent deformation and fracture

mechanisms, high- temperature properties of metals and alloys, and mechanical

properties of ceramics. Together these groups represent most of the

expertise in mechanical properties and in fracture mechanics at NBS.

The technical outputs of the Division assist many Government agencies,

especially the Departments of Energy, Transportation, Defense and Interior.

Recent emphasis on fusion, coal conversion, off-shore drilling and

geothermal energy has led to several efforts: low- temperature research

for structural containment of the large magnetic fields produced by

superconducting magnets, property characterization of geothermal cements,

study of high-temperature deformation and crack growth of coal -conversionsystem structural ceramics, the preparation of a handbook on coalconversion-system material performance. Transportation-related research

includes: research to establish inspection and allowable-flaw-size

standards for pipeline girth welds, mechanical -property and microstructural characterization of pressure-tank-car steels and railroad wheels,

fracture-mechanics assessment of tank-car behavior, development of test

562-3
standards for lightweight compressed gas cylinders, and numerous structural

metal-fracture analyses. Research for the Department of Defense is diverse.

We are assisting in upgrading Navy fracture-control plans, identifying

micro-creep limitations in ultrasensitive inertial-guidance-system

gyroscopes, studying the applicability of proof testing to nitride and

carbide ceramics that may be used in gas-turbine engines, conducting

erosion and wear experiments of ceramics to reduce machining costs,

studying the fracture and elastic characteristics of new silicon-carbide,

aluminum-based composites, and conducting large-scale panel tests on high-strength low-alloy steels.

The Division hosts and leads a number of workshops and conferences each

year. Collaborating with the Department of Energy (DOE), annual workshops

on "Materials at Low Temperatures" are hosted each year. The Mechanical

Failures Prevention Group, supported by the Divison, hosted two conferences:

"Damage Prevention in the Transportation Environment" and "Time-Dependent

Failure Mechanisms and Assessment Methodologies." This past year with

the Office of Naval Research the Division hosted a workshop on "Contact

Damage in Ceramic Materials at Elevated Temperature." The Division

actively leads and supports the International Cryogenic Materials Conference, which will hold its next meeting in Colorado Springs, CO.

New emphasis has been placed on non-destructive evaluation and characterization. Experienced scientists have been added to the Division in

Gaithersburg to initiate research in eddy-current scattering theory,

laser-based remote ultrasonic detection of flaws and acoustic emission

imaging and mapping. In Boulder, the research in theoretical modeling

and development of electromagnetic acoustic transducers has been expanded

from defect characterization to residual stress measurements.

The principal goal of the Fracture and Deformation Division is to minimize

material failure. There are three essential generic research thrusts to

improve material mechanical performance:

1. Theory and modeling of deformation and fracture lead to a fundamental understanding of the mechanisms of material mechanical response.

2. Characterization of mechanical performance is essential for

the proper development and selection of materials for service

applications and for efficient design that takes full advantage

of the performance.

3. Fracture-mechanics development and application provide quantitative assessment and standards for the integrity of critical

structures by relating material properties to flaw characterization and service environment.

The Fracture and Deformation Division focuses on long term research

emphasizing the critical areas of these three thrusts. These critical

areas, subsequently referred to as Tasks, are considered high risk and

are discussed in this report. Three principal research tasks have been

established to emphasize the research directions of our Division:

562-4
12121 FRACTURE MECHANISMS AND ANALYSES. Many advancing technologies

are restricted by the lack of understanding of time-dependent

deformation and fracture mechanisms. Failure analyses to assist in

understanding the causes of major national structural catastrophies

are also included in this task.

12122 DURABILITY OF CERAMICS AND COMPOSITES. Two areas of rapidly

advancing material utilization are composites and ceramics. Uses

of both material classes are primarily restricted by mechanical

performance.

12123 ELASTIC-PLASTIC FRACTURE MECHANICS. The development of

elastic-plastic fracture mechanics will provide the opportunity to

apply quantitative fitness-for-service criteria to the codes and

standards of critical structures.

FY82 Significant Accomplishments

Task 12121--FRACTURE MECHANISMS AND ANALYSES. Our program on fracture

mechanisms and failure analyses has as its objectives a broad spectrum

of goals: (1) the development of fundamental theories on crack-tip

structures and processes, (2) the generation of data to elucidate

these crack-tip mechanisms, (3) the development of fracture methodologies for predicting structural reliability, and (4) the application

of established methodologies in the analysis of actual failures. In

addition, the NBS Materials Durability Program has provided funding

for increased emphasis on high-temperature fracture processes and

mechanisms. Our understanding of the fracture of metals under timedependent conditions will be increased by research on crack-tip

theory coupled with high-temperature tensile, creep, and fatigue

properties.

• A generalized defect Green's function formalism was developed

for treating a crack as a crystalline defect. Decomposition

of the solution into a linear-elastic lattice solution and a nonlinear crack-tip core solution allows details of the cracktip cohesive interaction and of chemically assisted bond

rupture to be examined.

• Stability criteria of a sharp crack against intrinsic ductile

blunting by dislocation emission were examined with respect to

dislocation interactions in multiple emission events and the

prospects for combined cleavage and dislocation emission.

t Models have been developed to calculate the enhanced toughness

of ductile materials due to plasticity shielding of the cracktip stress field. Continuum calculations have been augmented

by discrete dislocation models with an essential feature of

these models being an elastic enclave, or dislocation-free

zone, ahead of the crack tip.

• A plastic yield strip model has been used to analyze a variety

of fracture related situations. When used to study residual

strength diagrams (a plot of failure stress versus crack size

562-5
for a cracked structure), the model demonstrates that the usual

categories of linear-elastic and elastic-plastic fracture

mechanics lose their distinction. The model has also been

successfully applied in the ASTM "Predictive Round Robin on Fracture" sponsored by Task Group E24.06.02.

• Diffusive mechanisms of cavity growth along grain interfaces

at elevated temperatures were examined in terms of the coupled

effects of elastic deformation and atomic diffusion. Three

regimes of crack growth response have been demonstrated which

range from equilibrium cavities in rigid grains to crack- like

cavities with elastic-plastic accommodation in the grains.

• Examination of the crack-tip geometry changes due to stressenhanced chemical dissolution has identified a stress regime

for stress corrosion cracking where enhanced blunting of the

crack tip occurs.

• Sustained load crack growth is being characterized in an aluminum alloy (2024-T6) at 423 K. Preliminary results suggest

both an incubation period prior to the onset of crack growth

and a threshold stress intensity factor below which no crack

growth occurs. The crack growth mechanism, as elucidated by

scanning electron microscopy, was time-dependent ductile hole

growth.

• To quantify the conditions required for the localization of

creep damage in a material, both cavity nucleation and growth,

and creep crack initiation have been investigated in the non- uniform, multi axial stress fields that occur in the vicinity

of a notch. Materials investigated include 304 stainless

steel, 7h Cr, 1 Mo steel, a reaction-bonded silicon carbide,

and a sintered alpha silicon carbide.

• A facility has been constructed for fracture testing of structural ceramics at elevated temperatures to 1900 K in controlled

gaseous environments such as oxygen, steam, carbon dioxide and

sulfur dioxide. Initial results for silicon carbide materials

indicate a sensitivity in the fracture behavior to both loading

rate and environment.

• A major investigation was conducted in conjunction with the

NBS Center for Building Technology to identify the prime

factors in the collapse of two walkways in the Kansas City

Hyatt Regency Hotel.

• An examination of the strength differential effect and the

associated "plastic" volume change has been examined in two

alloy systems (300 grade maraging steel and 7039 aluminum).

Results indicate that the strength differential effect and the

permanent volume expansion are not part of one phenomenon and

do not necessarily have to occur together.

562-6
Task 12122-DURABILITY OF CERAMICS AND COMPOSITES. Our program on ceramics and composites has as its objectives: (1) the generation

of new theory and data to elucidate fracture and deformation mechanisms in nonmetal lie materials; (2) the development of new techniques

for studying the fracture and deformation properties of materials;

(3) the collection of engineering data for structural applications;

(4) the investigation of processes that result in strength degradation and wear of nonmetal lie materials; and (5) the investigation of

the microstructure of nonmetal lie materials and its relationship to

mechanical behavior. Experimental techniques developed by the

Division permit measurements of the mechanical properties of composites

and ceramics over a wide range of conditions: in vacuum at temperatures to 2973 K, in corrosive environments at temperatures that range

from room temperature to 1873 K, and in cryogenic environments at

temperatures as low as 4 K. This range of experimental capabilities

is unique.

• The mechanism for stress cracking of oxide ceramics was identified by showing that molecular species having strong acid-base

character (H2 0, NH3 ) are the prime contributors to subcritical

crack growth of these materials.

• A new mapping procedure was developed as an alternative to the

pure fracture mechanics approach to lifetime prediction. An

approach such as this is required for high temperature structural

applications, for which flaw nucleation often occurs.

t The durability of cements for geothermal applications was evaluated in both "down-hole" tests conducted in Mexico, and hydrothermal tests conducted at the National Bureau of Standards. A

satisfactory correlation was obtained between the two types of

tests, suggesting that the less expensive laboratory test can

be used as a predictor of the behavior in geothermal environments.

• A dynamic hardness tester has been constructed, and is currently

being used to characterize the dynamic response of ceramic and

metallic materials to impulse loads. The instrument is capable

of delivering loads as high as 10 Newtons in times as short as

1 ms. All materials (copper, tungsten, glass) studied to date

increase in hardness as the impulse time is decreased.

0 The scanning transmission electron microscope was used to demonstrate plastic deformation in MgO during controlled crack growth.

Preliminary analysis of the dislocation patterns indicate that

dislocations from the crack tip do not lead to significant crack

tip blunting, a finding that is consistent with the "crack-tip

shielding" model of crack growth.

Task 12123— ELASTIC-PLASTIC FRACTURE MECHANICS. This task addresses

establishment of a science basis to develop fracture prevention

requirements for structural materials which exhibit plastic fracture

behavior and which are used in many commonplace engineering structures

such as bridges, pipelines, ships, and pressure vessels.

562-7
• Allowable flaw-size curves and EMAT inspection system were complete for gas- line girth-welds.

• Completed fitness-for-service assessment procedures for HY130

steel for naval structures using elastic-plastic-fracture

mechanics.

• Modeled influence of dislocation-shielding on crack-tip deformation.

• Developed a new test method to characterize crack arrest 'under

elastic-plastic conditions.

• Established capability to conduct elastic-plastic finite element

analyses of cracked structures.

• Validated test methodology for investigation of fatigue crack

growth in regions of contained plasticity.

• Developed theory and experimental procedures for measuring

residual stresses in textural plates using horizontal shear waves.

562-8
FRACTURE MECHANISMS AND ANALYSES

Task 12121

For structural materials, a knowledge of the fundamentals of crack-tip

structures and processes is essential to understanding fracture in these

materials and to predicting their long-term service life. Influences of

atomic structure and chemical reactions at crack-tips have been demonstrated. with atomistic models of fracture in a solid, but these influences

are only beginning to be confirmed quantitatively by experimental studies

of subcritical crack growth and environmental effects. Ductile processes

in the high-stress region of the crack tip are being introduced into

these atomistic models to assess the role of plastic deformation and to

extend the theoretical models to describe crack-growth phenomena such as creep crack growth and fatigue. High-temperature fracture is a complex

process with competitive fracture mechanisms, such as subcritical crack

growth, cavity nucleation and growth, and grain-boundary sliding; it is

affected by microstructure, impurity content and segregation, processing

history, and environment.

Failure analysis studies perform a valuable service for those Government

agencies that have no testing facilities and require research on the

safety of structural materials. By using modern metallographic, x-ray,

fractographic, and chemical analyses techniques and by maintaining a Failure Information Center, our Division serves as a focal point for

analyses and compilation of many critical structural failures.

Our Division program on fracture mechanisms and failure analyses has as its objectives a broad spectrum of goals: (1) the development of fundamental theories on crack-tip structures and processes, (2) the generation

of data to elucidate these crack-tip mechanisms, (3) the development of

fracture methodologies for predicting structural reliability, and (4) the

application of established methodologies in the analysis of actual

failures. In addition, the NBS Materials Durability Program has provided

funding for increased emphasis on high- temperature fracture processes

and mechanisms. Our understanding of the fracture of metals under timedependent conditions will be increased by research on crack- tip theory

coupled with high-temperature tensile, creep, and fatigue properties.

Fracture Theory

Subtask 1 of Task 12121

T.-J. Chuang, R. de Wit, R. J. Fields, E. R. Fuller, Jr., C. G. Interrante,

M. B. Kasen, I.-H. Lin, and R. M. Thomson

Predictions of crack growth and fracture and, hence, of component reliability can only be attained rationally through a fundamental understanding

of crack-tip structures and crack-tip processes. In this subtask,

theories are being developed to study these fracture mechanisms.

Lattice Theories of Fracture

The desire for understanding at a fundamental level has provided considerable impetus to atomistic modeling of cracks and crack-tip processes.

In previous research on a one-dimensional lattice model of a crack, we

562-9
showed how the discrete nature of bond rupture exhibits energy barriers

to brittle crack propagation and how these barriers resisting thermally

activated crack propagation are related to idealized interatomic force

laws for a material. A major result was the demonstration that the

formalism decomposes in a manner which illustrates that the driving

force for crack motion is supplied by the linear response of the entire

system to the external stress (i.e., the strain energy release rate) and

that the resistance to crack motion is supplied predominantly by the few

nonlinear interatomic interactions at the crack tip. From this result

we were able to place some bounds on the functional form for the stress

dependence of the crack growth rate. By utilizing a defect Green's

function approach, we have now generalized these results to two-dimensional

and, to some extent, three-dimensional crack configurations. This

extension allows us to consider aspects of the analysis related to more realistic crack configurations. Results indicate the importance of

details of the cohesive force laws on the specific character of fracture

phenomena and how chemi-cally assisted bond rupture at the crack tip

influences these phenomena.

Stability of Sharp Cracks Against Intrinsic Ductile Blunting

Another area where atomistic modeling of crack tip processes can provide

fundamental understanding is in assessing the role of ductile processes

in the highly stressed region near the crack tip. A basic question in

this regard is whether an atomically sharp crack is mechanically stable

in a crystal; or whether it breaks down in shear by intrinsic ductility

processes at the crack tip. We are not concerned here with the blunting

caused by dislocations which have been created by sources external to

the crack and which subsequently collide with the tip, but with the

basic stability of the tip configuration of a sharp crack in a crystalline

lattice. This problem was first addressed seriously by Kelly, Tyson, and

Cottrell, who compared the relative magnitudes of the maximum tensile

stress to the maximum shear stress in the vicinity of a sharp crack with

that of the theoretical tensile strength to shear strength of the material.

In a different approach, Rice and Thomson calculated the activation

energy barrier for spontaneous emission of a dislocation from the crack

tip. Since the stresses near a crack are highly inhomogeneous, and

there is significant dispersion in the phonon spectrum of crystals, it was thought by Rice and Thomson that calculation of an actual dislocation

emission event more nearly approximated the stability criterion for

materials. In recent considerations of these stability criteria we have

shown that the two approaches are basically equivalent in that they

reflect the same kind of physics behind the stability problem. This is an interesting result due to a comparison of computer simulation studies

by Tyson, which suggested that the two criteria lead to different results.

Further considerations of the stability criteria have addressed fundamental

issues regarding: the relationship between the activation energy for

dislocation emission and the Peierls energy; the interactions between

dislocations in multiple emission events with the possibility for an emission cut-off; the prospects for combined cleavage and dislocation

emission; and the influence of chemical attack on the stability criteria.

562-10
Dislocation Shielding of a Crack

When a crack is stable against spontaneous dislocation emission with its

concomitant crack-tip blunting, it is still possible for ductile processes

in the vicinity of the crack tip to contribute to an enhanced fracture

toughness. We think here of a sharp crack embedded in a material containing external dislocation sources distributed randomly around the crack

tip; but on probabilistic grounds, the tip is not likely to experience the

blunting catastrophe that would occur if a slip plane intersected the

exact position of the tip over a significant region of the crack front

and thereby destroyed its sharp character. Rather, slip taking place

ahead of the crack tip passes by without changing the geometric configuration of the cohesive zone, and slip taking place behind the crack tip

cuts the cleavage surface to create a macroscopical ly "blunted" crack.

Modeling of such fracture processes has developed by considering plasticity

effects both at a quasi-continuum level and at a discrete dislocation

level. In the quasi-continuum approach, a sharp crack contained in an "elastic enclave" is embedded in a continuum elastic-plastic material

with the continuum plasticity, due to atomistic considerations, being

required to cut-off at the elastic enclave boundary. Such models lead

to calculation of increased toughness due to plasticity shielding of the

stress field in the elastic enclave;, but specific results appear to be

model specific, depending strongly on estimates of the ratio of the

plastic zone radius to the elastic enclave radius. To address these

difficulties, models have been developed that consider the interaction

of discrete dislocations with the crack-tip stress field. In these

relatively self-consistent dislocation models, the boundary condition at

the elastic enclave is not a problem. The essential features of these

models are similar to the classical Bilby-Cottrell-Swinden (BCS) model

of one-dimensional slip in front of a crack, but include an elastic

enclave, or dislocation free zone, ahead of the crack tip.

Grain-Boundary Chemistry and Structure

Crack tip structures and crack tip processes are strongly influenced by

localized variations in chemistry. The predominant factor influencing

such variations is microsegregation; in particular, segregation to grain

boundaries. Although models based on thermodynamic equilibrium or vacancy-solute coupling have been proposed tc account for observed

segregate levels, their range of applicability has been limited. During

the past year, an analysis of data from an NBS study of solute redistribution during grain growth has defined a mechanism of segregation in which

grain boundary motion plays a dominant role. This analysis has given

rise to development of a general theory of segregation applicable to all

metallic systems and incorporating the ability to predict changing

segregate levels from the solute-free boundary condition through full

boundary saturation and to establish solute profiles and precipitate

development. The theory predicts development of microsegregated regions

in the interior of grains as well as at boundaries, consistent with the

observation of both intergranular and transgranular failure modes. A

unique aspect of the theory is the prediction of an athermal boundary

structural change that is activated by attainment of full boundary

solute saturation. The theory provides a method for a quantitative

correlation between the level and species of segregate, fracture toughness,

562-11
and crack growth rate. It also offers insight into the atomistic mechanisms operating at the crack tip. Details of these results were presented

at the Gordon Conference on Physical Metallurgy in July 1982.

Plastic Yield Strip Model

A plastic yield strip model has been used to analyze a variety of fracture

related situations. The model is based on a crack-tip opening displacement

(CTOD) model of Dugdale, Bilby, Cottrell, and Swinden (D-BCS), as extended

to finite geometries and structures by Heald, Spink, and Worthington

(HSW). The essential feature that the D-BCS-HSW model provides is an expression for the crack extension force, which includes effects of both

geometry and plasticity of the structure. Failure criteria are established

by comparing this extension force with the crack-extension resistance.

The model is described in a review of generalized failure criteria

presented at the 14th National Symposium on Fracture Mechanics. The

relationship between variant forms of this model, which have appeared in

the literature, are discussed in this review. This paper also includes

an extension of the concept of Hahn and Sarrate which says arbitrary

boundaries can be established to divide fracture behavior into three

categories: linear-elastic, elastic-plastic, and plastic collapse.

Using the plastic yield strip model, the fracture toughness of a pressure

vessel steel was correlated with the specimen strength ratio from data

reported by Server and Wullaert for several specimen configurations.

This correlation has the potential of replacing costly plane-strain

fracture toughness tests with simpler, and less expensive, specimenstrength-ratio measurements. A paper describing this correlation has

been prepared for publication.

The model, although approximate, presents a unified picture of failure

criteria and embodies many important features of the whole range of

fracture mechanics from linear elastic fracture mechanics to plastic

collapse. One such feature is exemplified in a residual strength diagram.

This is a plot of the failure stress versus crack size for a cracked

structure. In terms of this diagram, the model easily shows that for

increasing fracture toughness, decreasing flow stress, or decreasing

structure size, the category of linear-elastic fracture mechanics, and

subsequently elastic-plastic fracture mechanics disappear. This analysis

was presented at the Fifteenth National Symposium on Fracture Mechanics

in College Park, MD, on July 7-9, 1982.

The model has also been applied in the ASTM "Predictive Round Robin <?n Fracture" sponsored by Task Group E24.06.02 on Application of Fracture

Analysis Methods. It successfully predicted the failure load of 76

different specimens, consisting of three different specimen configurations

(tensile, compact tension and a specially designed "three-hole" specimen),

and of two different aluminum alloys with different crack sizes and

width dimensions. It is also planned to apply the model to analyze

pressure vessel failures as part of a study on railroad tank-car failures.

562-12
I

Fracture Mechanics Concepts

A "Survey of Fracture Toughness Testing and Data with Reference to

Meaning and Applications" was started in collaboration with Professor

George R. Irwin of the University of Maryland. One aspect of this

survey is "A Summary of Fracture Mechanics Concepts," which presents

concise definitions of the basis concepts of fracture mechanics, discusses

various crack propagation mechanisms, and concludes with the concept of

a fracture control plan. It will be published in the Journal of Testing

and Evaluation.

Diffusive Mechanisms of High Temperature Crack Growth

Research has continued on diffusive mechanisms of cavity growth along

grain interfaces at elevated temperatures. Growth is assumed to occur

by matter transport from the cavity surfaces into the grain boundary

under the influence of the applied stress. Gradients of the normal

stress acting on the interface drive the grain boundary diffusion,

whereas the stress itself is the sum of that due to the applied stress

plus a residual stress due to nonuniform matter addition to the abutting

grains by self-diffusion. The coupled effects of elastic deformation

and atomic diffusion result in a singular integral equation for stress,

which can be solved and leads to an equation correlating applied stress

to the cavity-growth rate. Three regimes of response are possible:

(1) for low stresses and growth rates, the cavities maintain their

equilibrium shape (Hull-Rimmer cavities) and grow in effectively rigid

grains; (2) for intermediate stresses and growth rates, the cavities

grow into a crack-like configuration (Chuang-Rice cavities), but the

grains can still be regarded as rigid; and (3) for high stresses and

rapid growth rates, the cavities maintain their crack- like configuration,

but now elastic-plastic accommodation in the grains must be considered.

Crack-Growth Mechanism Maps

Often our ability to assess a material's behavior in different environments and temperature regions depends as much on the form in which we present the engineering information as on the information itself.

During the past three years, a different method of expressing crack-growth

data has been developed that clearly delineates mechanisms of crack

growth as a function of temperature and stress- intensity factor. Contours

of constant material response, namely crack-growth rate, are plotted on

a diagram of the experimentally controllable parameters: temperature

and stress-intensity factor. This type of representation emphasizes

changes in a material's fracture mechanism as either the temperature or

the stress- i ntensity factor change, and thereby displays the variety of

ways that a crack can grow in a material. We have used these crackgrowth-mechanism maps as an aid in the critical evaluation of elevatedtemperature crack growth and fracture data. They provide a broad and

self-consistent picture of a material's resistance to crack growth and

clearly indicate regions where data either are missing or are contradictory.

These maps have been prepared for a number of materials, including a nickel-base superalloy, an aluminum alloy, a hot-pressed silicon nitride,

a hot-pressed silicon carbide, and a number of silicate glasses. We are now collecting crack growth data ourselves to generate additional crack

562-13
growth mechanism maps for various silicon carbide materials and for an aluminum alloy in two different tempers.

Stress Corrosion Induced Crack Tip Geometry Changes

Following the basic kinetic law of the well-known Charles and Hillig

theory, crack-tip geometry changes due to stress-assisted chemical

attack by a hostile environmental agent were investigated. In general,

four regions of geometry modification were identified depending on the

magnitude of the applied stress: (1) gross blunting when < a^;

(2) enhanced blunting near the crack tip when < CTA

< (3) gross

crack-tip sharpening when < a^\ and (4) crack-tip sharpening

with necking when a

^

< a^. Evaluation of the material's parameters

and ct^ for a typical material indicates Region 2 prevails in the range

of stress levels which can be realistically applied. Experimental

observations on stress corrosion cracking in soda-lime silicate glass

support these theoretical predictions.

Time-Dependent Fracture Processes

Subtask 2 of Task 12121

T.-J. Chuang, R. de Wit, J. G. Early, R. J. Fields, E. R. Fuller, Jr.,

G. E. Hicho, C. G. Interrante, R. F. Krause, R. S. Polvani, C. H. Brady,

L. Chuck, D. E. Harne, S. R. Low, and L. C. Smith

The objectives of this subtask are to investigate time-dependent fracture

mechanisms and to improve test methods for two generic categories:

(1) those fracture processes that are governed by environmental effects

on a material under sustained loading conditions, and (2) those fracture

processes that are influenced by a strain-rate sensitivity of the material".

As a counterpart of these objectives, these methods are applied to

significant materials problems.

Hydrogen Embrittlement of Steels

Hydrogen embrittlement of important structural alloys can result in

unexpected, catastrophic failure of metal components. Industrial users

of these materials often must employ costly strategies to reduce the

potential for embrittlement. Knowledge of bulk properties and average

stress levels is often not sufficient to predict the damaging effects of

hydrogen because local property differences may enhance embrittlement

susceptibility. A major problem in the study of hydrogen damage has

been the inability to detect and measure the local hydrogen-metal atom

interactions and the effects of stress fields on this interaction.

Neutron-inelastic scattering can be used to determine the effect of

local stress conditions on the local atomic interaction with hydrogen.

The combination of the strong interaction between dissolved hydrogen and

neutrons and the deep penetration of neutrons in structural alloys

offers the possibility for unique i_n situ measurements of the local

hydrogen- lattice environment. A series of prototype experiments based

on earlier results with other bcc metals have been initiated to directly

562-14
measure for the first time the local interaction of hydrogen in steel

using neutron-inelastic scattering techniques.

Additional studies on hydrogen embrittlement of steels have investigated

the environmental influence of hydrogen on sustained load crack growth.

These studies have included: (1) a measurement technique for the permeation of hydrogen in steels; (2) a method for removal of iron sulfides

from fracture surfaces that have been exposed to aqueous sulfide environments; (3) an examination of effects of temper embrittlement of steel on

its susceptibility to hydrogen embrittlement; and (4) development of an automated real-time method for analyzing crack-growth rates of steels

tested in aggressive aqueous environments. This year the automated

method of item (4) was applied to study the behavior of a 2.25 Cr to 1.0

Mo steel tested in an acetic solution containing H 2 S at 0.1 MPa (1 atm)

of pressure. A publication of the results of this work describes the

conditions that promote crack branching for this steel. These studies

involve computed rates of crack growth from dc electrical resistance

measurements of crack length in double beam (DB) type fracture-mechanics

test specimens. Future studies will include measurements taken with a more sensitive ac electrical resistance system, as well as results for some thicker, compact-tension (CT) type specimens. Variables that will

be included in future studies are tempering temperature for the 2.25 Cr

to 1.0 Mo steel, specimen orientation with respect to rolling direction,

and the partial pressure of H2 S in an aqueous acetic acid environment.

In addition, work is continuing on the determination of conditions that

promote the formation of branch cracks in DB specimens tested in severe sulfide environments. These studies of hydrogen embrittlement problems

have been conducted under the guidance of the Subcommittee on Hydrogen

Embrittlement of the Pressure Vessel Research Committee of the Welding

Research Council (WRC). Work on an interpretive report to be published

as a WRC Bulletin is now in progress. This work will be titled "Effects

of Hydrogen on Pressure Vessel Steels." NBS personnel are actively

participating in and promoting an international conference on "Current

Solutions to Hydrogen Problems in Steels," which is slated for November

1982 in Washington, DC. Over 70 manuscripts have already been edited

and accepted for these proceedings.

Creep Crack Growth

Another area of time dependent fracture response is crack growth at high

temperatures. Measurement of sustained load crack growth in an aluminum

alloy (2024-T6) at 423 K is in progress. The objective of this work is

to develop and evaluate techniques of crack growth measurement at high

temperatures, to measure the creep crack growth behavior in a few,

select materials of commercial importance, and, finally, to investigate

the mechanism of crack growth in these materials. To date, procedures

are established for fatigue precracking and dead-weight loading fracture

mechanics specimens at 423 K. From the resulting fracture surfaces, we

can observe the extent of creep crack growth and deduce an approximate

crack velocity versus stress intensity factor curve for this alloy.

Furthermore, there is evidence of both an incubation period prior to the

onset of crack growth and a threshold stress intensity factor below

which no crack growth occurs. Scanning electron microscope (SEM) examination of the fracture surfaces reveals that creep crack growth was by a

562-15
mechanism resembling the fast fracture mechanism, i.e., ductile hole

growth. However, the dimple density on the creep crack surface was considerably less than on the fast fracture surface. These findings

explain the origins of the incubation period and the threshold stress in

this material. They also shed light on the stress dependence of ductile

hole nucleation at inclusions. Further experiments will be conducted on the same alloy in a harder temper (T851), and ultimately these techniques

will be applied to high temperature crack growth in a heat resisting

steel. Measurements will be initiated of the crack length i_n situ using

an electric potential technique.

Creep Fracture Processes

Another mode of failure at high temperature is characterized by a general

degradation of a material's microstructure with time until fracture

occurs. This process is called creep fracture. Work involves investigating the nucleation, growth, and linkage of the creep cavities that

constitute the physical damage resulting in fracture under these conditions,

and developing hypotheses and performing experiments which elucidate the

role and interplay of these processes in the overall failure mechanism.

There are very few techniques which have sufficient resolution to study

the nucleation of creep cavities. Being only nanometers in diameter,

cavities at the nucleation stage of development can only be seen by high

resolution transmission electron microscopy (TEM). However, it is not

practical to make quantitative measurements by TEM because the number

density of cavities is too small. This drawback does not apply to

small-angle neutron scattering (SANS), which is sensitive to these small

cavities and can probe cubic centimeters of material. For this reason,

a program to measure the time evolution of the size distribution of

cavities using SANS was undertaken. Preliminary SANS studies have been

carried out on 304 stainless steel creep specimens.

In addition to the nucleation studies, the growth and spacial distribution

of creep cavities occurring around notches in 304 stainless steel and

2-1/4 Cr to 1 Mo steel have been monitored using quantitative microscopy.

Observations show the results of both nucleation and growth of cavities

in nonuniform, multi axial stress fields. This is providing the basis

for quantifying the conditions required for localization of the creep

damage in the region of the notch as opposed to a general degradation of

the whole specimen. The findings of this research were recently presented

at an international conference on defects, fracture and fatigue held in

Canada and will be published in the proceedings of that conference.

Finally, notched bend bars of a ceramic material are being treated at

very high temperatures to investigate the linking of the cavities to

each other or to the notch to form a critical crack that results in

rapid fracture. Details of this research were presented in August 1982

at the Gordon conference on Solid State Studies on Ceramics.

High-Temperature Fracture in Reactive Environments

Materials used in the elevated temperature regions of fossil-fuel fired

systems are subjected to the aggressive environments that are produced

562-16
by the fossil fuel combustion processes. These aggressive environments

can adversely influence the microstructural properties of these materials,

which in turn can influence the structural integrity of the material.

In addition, when a component constructed from these materials is subjected

to an applied stress, the environment and stress can act synergistically

to degrade the structural integrity of the component. Because of the numerous structural applications for ceramics in high-temperature regions

of coal conversion systems (e.g., heat exchanger and gas-fired turbine

components), an understanding of the critical factors that determine the

thermochemical/mechanical integrity of these ceramic materials is essential

To address these issues, a facility has been constructed at NBS for the

fracture testing of structural ceramics at elevated temperatures in

controlled gaseous environments. The system consists of an enclosed

electric furnace, capable of temperatures up to 1600 °C, which is installed

in an universal testing machine. The gaseous test environment, except

steam, is supplied to the furnace from tanks through a mass flow controller

A steam generator was constructed to generate the appropriate partial

pressure of steam. The total pressure is nominally one atmosphere and

the flow rate through the furnace cavity is nominally 500 mL/min. Using

this facility, fracture toughness tests have been conducted on chevronnotched, four-point flexural specimens of two silicon carbide materials

in an environment of nitrogen, oxygen, steam, carbon dioxide and sulfur

dioxide. These experiments were conducted as a function of both temperature and rate of loading. The value of toughness measured at rapid

loading rates determines the value of K^

c at that temperature, and the

values measured at the slower rates give an indication of the extent of

subcritical crack growth and/or creep blunting, yielding lower values in

the former case and higher values in the latter case. Results of these

fracture experiments for an alpha silicon carbide indicate very little

influence of either loading rate or environment. In contrast, a siliconized silicon carbide material shows a strong sensitivity to loading rate

and some sensitivity to environment. Future research with this facility

will also include high-temperature crack growth measurements.

Critical Evaluation of Four-point Flexural Test

Crack-growth experiments are often conducted in four-point flexure. A

critical evaluation of the use of four-point flexure techniques to

obtain crack-growth parameters was made to determine the precision and

accuracy of results obtained from these experiments. We first derived

the governing nonlinear ordinary differential equations which characterize

the time-history of the flexural test parameters for a given elastic

brittle material exhibiting a power-law crack growth behavior. A numerical

solution scheme was then developed which is capable of solving the

initial value problem, thus quantitatively assessing the influence of

crack growth on the load versus displacement output. The results of

this analysis show that (1) higher loading rates result in higher peak

loads, (2) conventional methods of evaluating Kj

c overestimated the true

value, and (3) for high N materials (where N is the exponent in the

power-law crack growth equation), the flexural test method yields a broad error band in the prediction for N and hence is not a reliable

562-17
technique. However, the technique still can be used to screen quickly

new materials which are potential candidates for structural applications.

Fracture Under Impact Loading

Impact-test studies in our laboratory have centered on both the pendulum

and drop-weight tests, which are used to measure the fracture toughness

of metals and alloys at high strain rates. Results of these impact

tests are often useful in fracture control, on the basis of either

service experience or empirical correlations with fracture mechanics

tests. Pendulum testing includes tests of both standard and precracked

Charpy V-notch (CVN) type specimens. Test-method-development activities

for CVN testing have involved our participation in ASTM activities on the development of standard test methods for precracked CVN specimens.

Results of our work will appear in a publication on the significance of

CVN precracking variables in determining test responses of precracked

slow-bend test specimens. Drop-weight testing includes dynamic-tear

(DT) tests and drop-weight NDT tests. Test-method-development activities

have involved publication of a method for computer-assisted testing and

data analysis for these impact tests. Future work will include results

of analyses of several alternative methods for the measurement of energy

absorption in DT and CVN tests. Applications in which impact testing

has been used to serve Government agencies include works on plate materials

used for railroad tank cars and in pipelines, as well as structural

steels used in highway bridges.

Microstructural Effects on Impact Fracture

Of considerable interest to many users of a material is the effect of

small variations in the microstructure of that material on its mechanical

properties. In conjunction with a NAVSEA program to develop an alternate

to HY 80 steel for use in ships and submarines, we are investigating the

effect of microstructural variations on the impact fracture properties

of a precipitation hardened HSLA steel. Variations in grain size and

precipitate distribution have been induced in this alloy by 27 different

austenitizing and thermal aging treatments. We are presently character-,

izing the microstructure using optical metallography, scanning transmission

electron microscopy, x-ray diffraction techniques, and small angle

neutron scattering. Charpy impact specimens are being prepared to

determine the impact properties of the various microstructures. The

impact behavior will be correlated to the microstructure and the heat

treatment where possible using existing theories of fracture by cleavage

and ductile hole growth. In particular, we will determine the sensitivity

of the impact properties of the alloy to variations in heat treatment

and microstructure.

Material Performance Center

Subtask 3 of Task 12121

B. W. Christ, H. Ondik, and T. R. Shives

The Material Performance Center assists the coal conversion industry in

extending the useful life and reliability of plant components by maintaining

a central source of information on the performance, especially failures,

562-18
of materials and components used in coal conversion environments. It

provides an integrated material -properties data base for construction

materials to aid in the design, construction, and operation of coal

conversion plants. Finally, it collects and evaluates the information,

maintains computer files for convenient retrieval, and disseminates the

data in convenient form to users.

Sources of the information compiled by the Material Performance Center

include operators of all gasification and liquefaction processes, from

bench-scale units through operating pilot plants participating in the

DOE voluntary failure reporting program. Information detail varies from

one-page failure-occurrence reports to final reports of laboratory

analyses of failed parts.

A computerized data base of approximately five hundred reported failures

has been established and is continually being updated, refined, and

increased as additional failure reports are received. Separate information

items addressing the same failure are collated when possible. In addition,

direct contact with operating personnel at the various process locations

and with failure analysis laboratory staff has enhanced the quality and

the flow of information and has assisted plant operators in problem

sol vi ng.

At present, the Center produces sets of abstracts covering all reported

incidents. The abstracts are intensive summaries constructed from the source document and they contain all reported data. They are sorted

according to material, component type, failure mode, and conversion

process, or any combination of these factors.

The major effort for the past year has been completion of a handbook,

Construction Materials for Coal Gasification--Performance and Properties

Data. This book contains data on mechanical properties and corrosion

resistance gained in practical plant experience and in laboratory testing

programs. It deals with the information in the context of eleven separate

component areas of coal gasification plants and draws from this information

an indication of possible candidate materials of construction. A separate

section of the book includes tabulated data for the chemical, physical,

and mechanical properties of candidate materials. The book consists of

loose-leaf pages so that extending and revising the data base can be

done periodically and easily.

Failure Avoidance Services

Subtask 4 of Task 12121

J. G. Early, C. G. Interrante, T. R. Shives, J. H. Smith, C. H. Brady,

D. E. Harne, S. R. Low, and L. C. Smith

Failure avoidance services provided to other Government agencies and

other Divisions within NBS include diagnostic failure analysis, mechanicalproperties testing, metal lographic analysis, and metallurgical consultation.

The results of this work have been used to assist in the development of

safety regulations, in the selection of materials to improve the reliability

of components and structures, and in the development of improved test

methods and standards. In many cases, diagnostic failure analysis of

562-19
failed components has led to the identification of needed research in

materials characterization, and this research is now part of the on-going

programs described in this report. During the present year, several

reports of specific projects in failure analysis and failure avoidance

were completed. As in previous years, projects were completed for the

National Transportation Safety Board, the Consumer Product Safety Commission,

the Federal Railroad Administration, and the Office of Hazardous Materials.

Special projects were completed for other Federal agencies. Reports of

these investigations are shown in the list of publications in this

report.

Failure Analyses in Transportation Systems

Contributions to a diagnostic failure investigation for the National

Transportation Safety Board (NTSB) were completed on a section of failed

gas pipeline. Results of this investigation are used by NTSB to identify

potential hazards in transportation systems and to advise the Department

of Transportation on the need for improved safety regulations.

Failure investigations were completed on failed piping and pressure

vessels for the Materials Transportation Bureau (MTB) of the Department

of Transportation. The results of these investigations are used by MTB

to develop a data base on failure experiences in pressure vessels and

piping and to determine if modifications to their safety regulation are required. A major investigation was completed to identify the cause of

leaking in a large liquefied natural gas (LNG) tank. This investigation

assisted the Department of Transportation in having the LNG facility

repai red.

Continuing work for the Federal Railroad Administration involves identification of the causes of failure in railway tank cars and wheels. For

tank cars, the work involves considerations for fracture safe design and

improved materials to resist fracture in the event of tank-car accidents.

The current studies involve the application of a plastic yield strip

model to analyze failure criteria for tbrough-cracked pressure vessels

(for further description of this modeling effort, see the description of

this model in Subtask 1). The extreme hazard resulting from frequent

accidents involving tank cars containing hazardous materials is a national

problem of growing significance. Results of the NBS work on tank-car

materials have assisted in the development of specifications for new tank cars that will significantly reduce the frequency of major tank-car

accidents. For railroad wheels, current efforts are focused on analyses

of selected wheels failed in service and residual stress of wheels in

service.

Failure Analyses in Consumer Products

Electrical receptacles thought to be possible initiation sources of

residential fires were examined for the Consumer Product Safety Commission

(CPSC). The results of this investigation may be used by CPSC to assess

the need for modifications to the design of materials used in these

products to reduce the risk of injury to the public.

562-20
Failure Analysis of the Kansas City Hyatt-Regency Hotel Walkways

A major investigation was conducted in conjunction with the NBS Center

for Building Technology to identify the prime factors in the collapse of

the two Kansas City Hyatt Regency Hotel Walkways. The results of this

investigation are expected to lead to a better definition of responsibility

in building construction, ranging from code enforcers through detail ers,

as well as to a better definition of required inspection during construction.

This investigation was also carried out in response to the right of the

public to know how and why such a catastrophic accident occurred.

Mechanical Failures Prevention Group

The dissemination of information to assist in Failure Avoidance was continued by the NBS sponsorship of two meetings of the Mechanical

Failures Prevention Group (MFPG). These meetings were organized by the

Fracture and Deformation Division. A meeting with the theme "Damage

Prevention in the Transportation Environment," was held in October 1981.

The April 1982 meeting addressed the theme, "Time-Dependent Failure

Mechanisms and Assessment Methodologies," which generated substantial

participation from both the industrial and academic sectors as well as from government laboratories. The Symposium had a strong international

flavor with contributed papers from Canada, Great Britain, France, and

Denmark and successfully focused on the theme of relating assessment

methodologies to time-dependent failure mechanisms. A diversity of

mechanisms, including dynamic machinery failure, stress-corrosion cracking,

elevated temperature failure, delayed failure, and wear were discussed

and illustrated for various materials, including metals and several

classes of non-metals.

Plastic Deformation of Metals

Subtask 5 of Task 12121

B. W. Christ, R. de Wit, R. J. Fields, E. R. Fuller, Jr., G. E. Hicho,

and R. S. Polvani

Microdeformation of Metals

The commercial importance of dimensionally stable members and structures

is the basis for this research. Frames and fixtures for metrology, for

inertial guidance systems in both commercial and military uses, and for

communication "mirrors" are all examples of commercial applications

which depend on this common feature of different construction materials.

The program addresses microdeformation in these materials, by studies of

response to various modes of loading. An information data base is

developing which will include both the microyield strength and the

microcreep characteristics (for up to several thousand hours in some

cases). The materials under study are aluminum, beryllium, gauge block

steel, and Super Invar. The overall technical goals of this study are:

(1) to develop a data base, and preferably a model, for the dependence

of the deformation on very low stresses at temperatures near room temperature (with typical strains of less than 10~6

); (2) to characterize the

interdependence between the yield and the creep modes; and (3) to develop

a fundamental understanding of the dislocation processes that limit

562-21
microstrains. The program involves the combined efforts of NBS workers

in Materials Science and Metrology, along with researchers at the

C. S. Draper Laboratory (Cambridge, MA), Lawrence Livermore Laboratory

(Livermore, CA), and Rockwell International (Huntington Beach, CA).

To study microdeformation, three different test systems have been developed

at NBS. Two of these systems are for uniaxial measurements and the

third system is for biaxial creep. All three systems have a basic

resolution of 10-8 strain, but have different scatter bands for long-time

data. Using capacitance gauging, the two test frames for one of the

uniaxial systems have scatter bands within a limit of 10~7 strain. The

other uniaxial system uses a polarizing laser interferometer and is

expected to have a much narrower scatter band on the order of 10-8

. Performance of the 10-8 system is still being evaluated along with the

initial 14,000 hours of test results from the six biaxial test frames.

Using the 10-7 strain system for testing 1-400 microcreep was found to

have several notable features. Firstly, the creep strain depends linearly

on the applied stress between 100 kPa and 200 MPa, and within the limited

temperature range of interest (298 to 373 K), has no obvious temperature

dependence. Secondly, the microcreep curve depends on the logarithm of

time rather than a power of time. And lastly, the microcreep behavior

is dominated by strain hardening, and after several hundred hours, an apparent "exhaustion" occurs. All three features of the microcreep

behavior are consistent with Cottrell's "Exhaustion Creep Theory". In

additon, a tie between the microcreep and microyield strength was found.

Currently, the obstacle to the development of a firm correlation between

the two deformation modes is the need for a better analytical approach

for determining the microyield strength.

Statistical aspects of fitting microcreep data to creep relationships

are also being developed. Confidence limits for various nonlinear curve

fits have been established which allow extrapolation of the microcreep

strains to times beyond the test times. This extrapolation can be done

for several creep theories, including Hart's model for exhaustion creep.

Next year, the focus will be on increased consideration of test materials

other than 1-400 beryllium, development of a better method for determining

the microyield strength, and further consideration of Hart's theory of

exhaustion creep.

Dynamic Hardness

Because of the importance of hardness to the nucleation of cracks and to

other wear mechanisms during erosion, an attempt is being made to measure

the dynamic hardness of metals and ceramics. This is a joint effort of

Tasks 12121 and 12122. Two approaches were taken to obtain estimates of

dynamic hardness. One of these approaches was directed at the characterization of acoustic signals generated during impact, so that an impact-load,

time profile could be obtained for real-time impact situations. The

impact apparatus has been constructed, is currently operational, and is

being used for investigations of dynamic hardness of metals and ceramics.

The other approach for measuring dynamic hardness uses an electrically

driven hardness indenter. The apparatus--as now constructed--operates

562-22
over several decades of time, 10

"4 to 10 -4 seconds; and more importantly

is capable of developing several different wave forms for the penetration

load. These shapes include: (1) impulse, (2) triangle, (3) square, and

(4) ramp. By using a linear current gain amplifier penetration loads up

to 10 Newtons can be used to study the effect of rate on the microhardness

of materials. Current emphasis for the equipment development is in

devising a means of sensing the displacement of the indenter into the

sample. This will be done using electrical transducers.

Microstructural Effects On Plastic Deformation

In conjunction with the investigation of microstructural effects on impact fracture (see Subtask 2 of Task 12121), we are also studying the

effect of microstructural variables on the yield stress, the hardness,

and the strain hardening and plastic instability behavior, of a precipitation hardened high strength low alloy (HSLA) steel. Here, we have

induced variations in grain size and precipitate distribution in this

one alloy by variations in austenitizing and aging treatments. We are presently characterizing the microstructure using optical microscopy,

scanning transmision electron microscopy (STEM), and SANS. We will soon measure the plastic properties and correlate them with the microstructure

when possible using elements of dislocation theory. Most importantly

for users of this steel, we will determine how sensitive the deformation

behavior of this steel is to variations in heat treatment and microstructure.

Strength Differential Effect

Most design codes assume that the yield stress in tension is the same as that in compression. Over the past year, we have been studying the

microstructure and physical properties of alloys which exhibit a 5 to

10 percent difference between yield stresses in tension and in compression.

Of the various hypotheses offered in the literature to explain this

phenomenon, we have found that only one, based on a pressure dependent

coherency strain around precipitates, applies to the alloy systems

studied here (300 grade maraging steel and 7039 aluminum). We have

derived analytical expressions which not only predict the existence of a strength differential, but which quantitatively give the correct magnitude

in the case where data are available. These expressions are deterministic

and based only on two fundamental quantities: the elastic moduli and

lattice parameters.

There is often a permanent or plastic volume expansion associated with

the deformation of materials exhibiting a strength differential. Since

the mathematical theory of plasticity usually assumes plastic incompressibility, the above permanent volume expansion has far reaching effects

when calculating the plastic deformation in such materials. We have

measured such an expansion as a function of plastic strain using high

resolution density determinations. The physical source of this expansion

was sought using optical metallography, wide angle x-ray and neutron

diffraction, scanning transmission electron microscopy, and small -angle

neutron diffraction. The tentative conclusion from these investigations

at present is that the strengthening precipitates are being cut up and

redissolved by the dislocation motion associated with plastic deformation.

Further work in the TEM and STEM is in progress. We also intend to use

562-23
I

differential scanning calorimetry and i_n situ resistivity measurements

during straining to investigate further the physical source of the

permanent expansion. It appears at present that the strength differential

and the permanent volume expansion are not part of one phenomenon and do

not necessarily have to occur together.

Test Methods and Standards

Subtask 6 of Task 12121

J. G. Early, R. J. Fields, G. E. Hicho, C. G. Interrante, J. H. Smith,

and D. E. Harne, S. R. Low, and L. C. Smith

The development of test methods and standards for characterizing and

specifying materials is a major activity of the Fracture and Deformation

Division. The need for specific test methods and materials standards is

often initially identified through our failure-avoidance efforts conducted

for other Government agencies. The current activities are summarized as follows:

Development of Standard Reference Materials (SRM)

Under the sponsorship of the NBS Office of Standard Reference Materials,

SRMs have been prepared to aid in the calibration of x-ray diffraction

equipment used to determine the percentage of retained austenite in

hardened steels. Austenitic stainless steel (AISI 310) and ferritic

stainless steel (AISI 430) powders were blended, compacted, and sintered

using powder metallurgical techniques. The samples were then calibrated

using x-ray fluorescence and quantitative metal lographic technique and

certified for sale. During the past year, 200 - 5%, 200 - 30%, and

400 - 2.5% austenite in ferrite SRMs were offered for sale by the Office

of Standard Reference Materials. The availability of this series of

SRMs is essential for the accurate calibration of x-ray diffraction

equipment which is used for determining the retained austenite in ferrous

materials purchased according to specifications that place a maximum on the amount of retained austenite allowed. In the coming year, the

possibility will be explored for the development of a SRM containing

10 percent ferrite in an austenite material. This SRM would be used to

characterize the volume percent of ferrite in stainless steel welds.

Standard Test Methods for Hydrogen-Assisted Cracking

Hydrogen-assisted cracking (HAC) is a significant cause of unexpected

fracture in structures made from ferrous alloys. Reliable test methods

for assessing the susceptibility to HAC are required to reduce the costs

associated with these failures through control plans that use crack-growthrate data and threshold fracture-toughness data. A method for real-time

measurements of crack-length and crack-growth rates, and hence stressintensity and threshold fracture toughness, in double-cantilever-beam

(DCB) test specimens has been developed at the NBS. This test method

has broad applicability for studies of the fracture behavior of metals

and alloys in environments that promote slow crack growth. This year,

the application of this method has resulted in two publications: one on the solutions to the problem of crack branching in test specimens subjected

562-24
to aggressive environments; and another on a method for obtaining quantitative relationships between the aggressiveness of an aqueous environment

and the susceptibility of steel to cracking. This work is conducted

under the guidance of the Pressure Vessel Research Committee of the

Welding Research Council.

In earlier work on the measurement of the thermal diffusivitiy of hydrogen

in metals, an original test method was developed at the NBS using palladium

specimens. This test method has applicability to the diffusivity of

hydrogen in ferrous alloys, and it can be used for assessing the potency

for hydrogen charging associated with various hydrogen/metal systems.

A project has been initiated to use neutron-inelastic scattering to

determine the effect of local stress fields on the local atomic interaction between hydrogen and iron atoms in specimens of steel under stress.

Modifications to the NBS reactor time-of-fl ight spectrometer have been

completed. Tests carried out on nonferrous alloys by Reactor Radiation

Division staff indicate that hydrogen detection in the 1 to 100 ppm

range is feasible.

Development of Test Methods for Assuring the Safety of Pressure Vessels

Research is continuing on programs for the Office of Hazardous Materials

Regulations (OHMR) to develop appropriate test methods and to provide

the basis for developing standards for the safe shipment of hazardous

materials in portable pressure vessels. Work has been completed on assessing the validity of various mechanical properties tests used for

acceptance of homogeneous seamless steel cylinders. The results of this

program will permit a fair and equitable comparison to be made between

cylinders manufactured in the U.S. and those in foreign countries and

will ensure the same level of safety for all classes of cylinders. A

program has been initiated to assess the fracture toughness of various

cylinders and to assess the need for requiring fracture toughness specifications on materials used in seamless steel vessels.

An extensive program was initiated this year to develop reliable test

methods and acceptance standards for the use of composite pressure

vessels in the transportation of hazardous materials. At present,

attention is focused on cylinders made by overwrapping aluminum cylinders

with fiberglass-reinforced plastic and Kevlar. Tests are being assessed

and developed for assessing the safety of these vessels in ambient

environments, high temperature environments, and in aqueous environments.

The results of these tests will be used by OHMR to develop specifications

for allowing wide-scale use of composite cylinders.

Determination of Elastic Moduli Using Sonic Techniques

The Young's and shear moduli, and Poisson's ratio were determined for a 9310 gear steel using both the pulse echo and sonic resonance techniques.

Three cylinders and nine strips (three strips representing one of the

three orthogonal directions in the gear) of the steel were evaluated for

these elastic criteria. Pulse echo results indicated that both the

Young's and shear moduli could be determined with an uncertainty of

562-25
0.5 percent. Sonic resonance results for these same moduli (using only

the strips) agreed quite favorably with those obtained using the pulse

echo technique.

Analysis of Shipbuilding Materials Standards

Under United States law, United States flag vessels must satisfy applicable

United States codes and further, the materials of construction of these

vessels must satisfy the material requirements specified in these codes.

For vessels manufactured in foreign countries, a determination must be

made as to whether materials of construction produced under foreign

specifications for specific components such as piping and flanges, are equivalent in performance to materials produced under approved United States

specifications. The evaluation process used by inspectors for determining

the compatabi 1 ity between approved domestic material specifications and

foreign specifications is often not uniform.

Under sponsorship of the U.S. Coast Guard, a major study was completed

which contained detailed technical comparisons between foreign material

specifications, principally Deutsche Industrie-Normen (DIN) standards

and Japanese Industrial Standards (JIS), and selected domestic material

specifications. This comparison identified technical areas of commonality,

difference, and omission that could have a significant impact on component

performance. The final report identifies those foreign material specifications that are equivalent to acceptable domestic specifications, those

foreign specifications that are not equivalent, and those that would be

equivalent if certain additional criteria were met. The Coast Guard

will use the conclusions developed in this study to reduce the current

case-by-case determination of equivalence and the inherent danger of

inconsistent determinations of equivalence. With the encouragement of

the Coast Guard, the report will be distributed throughout the domestic

and foreign standards communities. An invited talk and paper detailing

the approach used in carrying out this study have been given to the

Society of Naval Architects and Marine Engineers.

Currently, work is being focused on the completion of a manual describing

specific technical criteria and methodologies to be used in making this

type of comparison. This manual will assist Coast Guard personnel and

shipyard inspectors in making new evaluations of materials acceptability.

Development of Standards for Resource Recovery

The development and operation of resource recovery systems has been

hindered by the absence of widely accepted national standards and specifications and test methods applicable to materials recovered from municipal

solid waste. There is a strong need for quantitative specifications for

materials recovered from municipal solid waste. Although the value of

recovered materials generally increases with purity and homogeneity, the

key to the usefulness of these materials, and thus their potential for

increased markets, is the ability to ensure a reproducible quality.

Often it is the uncertainty over impurity content that causes potential

buyers of recycled materials to and demand unnecessarily higher levels

of scrap quality.
Recognition of this problem led the American Society for Testing and

Materials (ASTM) to create a committee to bring together representatives

of many diverse interests in this new field for the purpose of developing

standards. An important goal of this process of developing consensus

standards was to insure significant participation of all interested

parties, especially the intended users of these standards, so that a strong incentive is created to apply the standards in the market place.

Working with representatives of resource recovery facilities, Federal

and 'state agencies, and industrial consumers of ferrous scrap, the first

two national consensus standards for municipal ferrous scrap have been

formally adopted by ASTM. With the adoption of these standards, Subcommittee E38.02, Ferrous Metals, with NBS staff in a leadership role, has now focused their efforts on developing an adequate data base for establishing precision and accuracy limits for the ferrous scrap test methods.

A round robin test program with six participants has been created to

develop this data base. With the cooperation of an agency of the Ontario,

Canada government, almost one hundred synthetic samples of ferrous scrap

were prepared and distributed to the participating laboratories. Currently,

the raw test data is being collected for analysis at NBS. Completion of

the testing phase is expected by fall 1982 and the final analyses reported

in the spring of 1983.

Terminology

Our work in the area of terminology is concerned mainly with terminology

for fracture testing. It includes staff participation in an international

committee, ISO TC164/WG on Terminology for Mechanical Testing, as well

as in several national committees, the ASTM Committee on Terminology,

ASTM Subcommittee E-24.05 on Terminology for Fracture Testing, and the

ASM of Committee on Definitions of Metallurgical Terms. The Chairperson

and Secretary of Subcommittee E-24.05 serve in a diversified set of

roles to facilitate and coordinate the development of terminology within

the many task groups of the eight subcommittees of Committee E-24. This

terminology includes development definitions, description of terms,

recommended symbols, abbreviations, and units, as well as guidelines for

use of the SI Metric Practice. Another aspect of this work is the

coordination of the terminology of E-24 with that of other ASTM committees

and other national and international bodies concerned with terminology

for fracture testing.

This year, the Standard Terminology for Fracture Testing was substantially

revised and published as E616-82 in Part 10 of the ASTM Book of Standards.

It now includes a standard code for designations for test specimens. In

still another effort aimed at promotion of standard terminology, one of our staff co-chaired an international symposium titled "Terminology:

The Cornerstone of Global Communications Through Standards," which

received good international support and will likely result in the publication of the proceedings, as an ASTM STP.

562-27

DURABILITY OF CERAMICS AND COMPOSITES

Task 12122

Ceramic materials are used where special properties, such as chemical

resistance to corrosive environments, mechanical resistance to erosion

and wear, and mechanical and chemical resistance to temperature extremes,

are required. In commercial applications they are used as substrates

for electronic packaging, containers for nuclear waste disposal, linings

for geothermal wells, components for high-temperature gas turbines and

heat exchangers, thread guides and wear surfaces for the manufacture of

paper and clothing, cutting tools and cutoff wheels for the shaping and

finishing operations used in the manufacture of various machines and

tools, and insulating linings for reactors and furnaces in the coalconversion and petrochemical industries. In defense applications, these

materials are used as radomes, missile nose cones, turbine components in

portable electric-generating facilities, electronic guidance systems and

bearing surfaces in gyroscopes. Because they are brittle, ceramics are usually over-designed mechanically to avoid fracture during use. The

investigation of the fracture and deformation properties of these materials

is need to overcome technical difficulties associated with the brittle

behavior and to permit ceramics to be used in a wider range of applications.

Composite materials are highly engineered, heterogeneous materials

designed to impart unique properties not achievable with conventional

materials. Composites offer the possibility of high-strength, lightweight,

durable structures. In typical advanced composites, the strength-to-weight

ratio is an order of magnitude larger than that in normal grades of

steel. Extensive commercialization of composites will result in major

energy and materials savings, increased productivity, improved product

safety, and improved U.S. technological innovative capabilities. For

effective industrial utilization of composites materials, better understanding of their wear-out and fracture mechanisms is needed. Test

methodologies and standards must be developed, the effect of flaws and

interface debonding must be assessed, and damage accumulation must be

accurately inspected and evaluated.

Our program on ceramics and composites has as its objectives: (1) the

generation of new theory and data to elucidate fracture and deformation

mechanisms in nonmetal lie materials; (2) the development of new techniques

for studying the fracture and deformation properties of materials;

(3) the collection of engineering data for structural applications;

(4) the investigation of processes that result in strength degradation

and wear of nonmetal lie materials; and (5) the investigation of the

microstructure of nonmetallic materials and its relationship to mechanical

behavior. Experimental techniques developed by the Division permit

measurements of the mechanical properties of composites and ceramics

over a wide range of conditions: in vacuum at temperatures to 2973 K,

in corrosive environments at temperatures that range from room temperature

to 1873 K, and in cryogenic environments at temperatures as low as 4 K. This range of experimental capabilities is unique.

562-29
Fundamentals of Fracture

Subtask 1 of Task 12122

S. W. Freiman, E. R. Fuller, Jr., S. M. Wiederhorn, B. R. Lawn, E. Case,

and T.-J. Chuang

In this subtask, studies are being conducted on basic fracture and

deformation processes in ceramic materials. During the past year, our work on this subtask included the development of an understanding of

mechanisms of subcritical crack growth in glass. Glass was selected as

a material for study because of its practical value and because it serves as a model for other brittle ceramics that are susceptible to

subcritical crack growth. In addition to the work on glass, crack

growth studies were conducted on crystalline materials.

Chemical Reactions at Crack Tips

Mechanisms of reaction between chemical environments and glass are being

studied. During the past year, the importance of hydrogen to the crack

growth rate was investigated by fracture mechanics techniques. A comparison

of crack growth rates for silica and soda-lime silica glass in H2 0 and

in D 2 0 has shown a positive contribution of the hydrogen atom to the

overall chemical process. Studies on soda-lime silica glass conducted

in 1 N DC1 and 1 N NaOD solutions suggest that the isotopic effect of

D 2 0 on crack growth is only observed in basic environments. For the

present we have no explanation of this observation. During the coming

year studies in acidic and basic D 2 0 environments will be conducted on silica glass to determine if the isotopic effect on crack growth is

similarly dependent on pH for this glass.

A chemical route to subcritical crack growth in glass was established by

demonstrating that only environments with the ability to act both as electron acceptors and electron donors cause crack growth in silica

glass. These studies have been extended to soda-lime silica glass and

it appears that the mechanism of crack growth in this glass is identical

to that in amorphous silica. No direct participation of the Na ions in

the crack tip reaction was observed. Thus, the mechanism of crack

growth hypothesized for silica glass appears to be equally applicable to

soda-lime silica glass. We suspect that this mechanism of reaction is

generally applicable to all glasses.

Our work on subcritical crack growth in brittle materials is being

extended to include a variety of environments and materials (other than

glass). Thus, studies have already been initiated to investigate the

applicability of the electron donor- acceptor concepts (discussed above)

to single crystal MgF 2 and A1 2 0 3

. These studies are being conducted in

collaboration with Dr. T. A. Michalske of Sandia National Laboratories.

Results to date indicate that A1 2 0 3 (sapphire) is very similar to silica

glass in its behavior, suggesting that oxides may undergo the same types

of crack tip reactions as glasses. In contrast, crack growth in more

ionic solids appear to be controlled by electrostatic interactions

rather than acid-base reactions with the environment. This conclusion

is based in part on isotope studies on MgF2 which suggest that protons

play no role in the crack tip reaction.

562-30
A paper, "A Molecular Interpretation of Stress Corrosion in Silica," by

T. A. Michalske and S. W. Freiman has been published in Nature. A more complete description of the silica studies has been submitted to the

Journal of the American Ceramic Society. In addition to these, two

papers, one on soda-lime silica glass, the other on A1 2 0 3 and MgF 2 , were

presented at the Annual Meeting of the American Ceramic Society.

Crack-Tip Geometry Changes During Crack Growth

In addition to the work on crack tip reactions, the potential effect of

these reactions on crack tip geometry was studied. Following the basic

kinetic law of the classical Charles and Hillig theory, the change in

the crack-tip geometry due to a stress-assisted chemical attack of the

environment was examined. Two extreme cases were identified. In the

first case the linear term in stress (i.e., the activation volume) is

assumed to disappear from the kinetic equation. In this case, the

fatigue limit is found to be approximately 0.8 times Griffith stress,

which is the same value as predicted by the Charles and Hillig treatment.

Crack sharpening accompanied by necking is also predicted if the applied

stress exceeds this fatigue limit. In the second case, the quadratic

term in stress (i.e., the strain energy term) in the kinetic law is

neglected leaving the activation volume term as the dominant term. For

this condition stress enhanced crack tip blunting is expected for a range of applied stresses. Experimental data indicates enhanced crack

tip blunting and hence suggests that case two is more appropriate for

the description of stress corrosion cracking in soda-lime glass.

New Approaches to Fracture and Deformation

Subtask 2 of Task 12122

E. R. Fuller, Jr., S. M. Wiederhorn, R. J. Fields, T.-J. Chuang,

N. J. Tighe, E. D. Case, and G. S. White

The techniques of fracture mechanics have provided engineers with new

and powerful techniques to evaluate the mechanical behavior of materials

and to estimate the total allowable lifetime when a structural material

is subject to mechanical forces. When the mechanism of failure is well

understood, fracture mechanics techniques may be used directly to obtain

a prediction of lifetime. When the mechanism of failure is not well

understood, fracture mechanics in combination with probability theory is

needed to develop a framework for structural design. In either case, it

is important to be able to characterize the flaw size and the rate at

which flaws grow in ceramic materials. A major portion of the work on this subtask during the past year was directed towards achieving this

goal. The work can be divided into four projects, which are in various

stages of completion: (1) Optical Nondestructive Evaluation (NDE)-Light

Scattering; (2) Effect of Microcracking on Elastic Properties; (3) Crack

Parameters from Strength Tests; (4) Strength Degradation Maps.

Optical NDE: Light Scattering

Quantitative evaluation of surface cracks and defects is an increasingly

important concern in NDE. However, because of mathematical difficulties

in dealing with shapes of defects, use of scattered light as a quantitative

562-31
tool is limited. This project compares theoretical and measured scattering

from simple surface defects. Scattered optical radiation patterns from

a v-shaped groove were compared to calculations from an exact theory

(developed by D. Maystre). The theoretical calculations were based upon

actual diamond stylus profile measurements of the groove cross section.

The theory was found to give excellent agreement with experiment, predicting the observed number and positions of the scattering peaks. Certain

discrepancies between calculated and measured scattering patterns were attributed to finite beam size and variations in groove cross section.

Nevertheless, these discrepancies were minor and agreement between

theory and experiment was good.

Because the exact theory is cumbersome and expensive to use (due to the

need for computer calculations), it is of interest to determine the size

of defects at which Fraunhofer approximations can be used. Accordingly,

next year, measurements will be made on scattering from grooves with

trapezoidal cross sections varying in size from the resonance domain

limit to the Fraunhofer region. These measurements will be compared

with both the approximate and exact calculations of scattering to yield

information on the relation between the flaw geometry and the observed

scattering patterns.

Effects of Microcracking on Elasticity

Because microcracking in the form of cavitation is an important mode of

strength degradation at elevated temperatures, characterization of the

effect of microcracking on bulk properties of ceramics may provide a means of monitoring the strength of these materials at elevated temperatures. With this objective in mind, investigations were conducted to

establish the theoretical basis for such characterization. Four

microcracking-modulus decrement theories were examined to ascertain

their predictive capability. Examination of elasticity data from several

microcracked ceramic oxides demonstrated similar trends for the predicted

Young's modulus Poisson's ratio behavior of microcracked specimens.

Experimental-elasticity data were found to be in general agreement with

the predicted trends.

In another part of this investigation, we discovered that YCr0 3 could be

used as a model material for microcracking studies. Because this material

undergoes an apparent phase transition at 1100 °C, and because the

micro.cracks heal at temperatures less than 1100 °C, it is possible to

control grain size and crack size independently. This control is achieved

by first sintering the material at ^ 1750 °C to obtain the desired grain

size and then microcracking and annealing the material at < 1100 °C to

obtain the desired crack size. Thus, microcracked specimens may be

produced for a range of experimental purposes, all of which have the

potential of yielding a more detailed understanding of the effect of

cavities or microcracks on strength.

High Temperature Structural Ceramics

A critical evaluation of the feasibility of obtaining crack growth

parameters from four-point bend tests was made. The governing nonlinear

562-32
ordinary differential equations are derived to characterize the timehistory of bend test parameters for a given elastic brittle material

exhibiting power law crack growth behavior. A computer algorithm was then developed to solve the initial value problem, and thus assess the

influence of crack growth on the load-displacement output. The results

of this analysis indicate that for high N materials (where N is the

' exponent in the power law crack growth equation) the flexural test

method gives a broad error band in the prediction of N and hence is not

a reliable test technique. However, the technique can be used by a designer to screen new materials with high N values.

In addition to the work discussed above, the critical stress intensity

factor, Kj

c

, was determined as a function of temperature for several

commercial grades of silicon carbide. Chevron-notched bend bars were

used for these measurements because these specimens produce sharp precracks

prior to rapid fracture. The Kj

c measurements by this technique are subject to a minimum amount of scatter, and hence, are considered to be

highly reliable. Measurements of Kj

c made at two loading rates suggest

that strong loading rate sensitivity is exhibited by materials that are also creep and crack growth sensitive at the temperature of measurement.

These studies will be continued into the new year on a variety of ceramic

materials. The results of these studies will be incorporated into crack

growth mechanism maps.

Cavitation Crack-Growth

Creep resistant SiC-based ceramics fail by the growth and linkage of

preexisting pores. To study the kinetics of this process, notched bars were loaded in bending for times up to 150 h at 1300 and 1350 °C. These

specimens were loaded at a nominal stress intensity factor of 0.8 Kj

c> After exposure the specimens were removed from the furnace, polished,

and examined using quantitative metallographic techniques. From these

microscopic examinations it was apparent that the cavities grow by the

diffusion of material from the cavity surface to the adjacent grain

boundary. The stress distribution in a creeping bend specimen is currently

being analyzed in order to test the applicability of the Chuang-Rice

theory of diffusive crack growth. The details of this work will be

presented this summer at the Gordon Research Conference on Solid State

Studies in Ceramics.

These interrupted tests will be continued next year on various grades of

commercial Si C ceramics. The results of these studies will be used to

determine the regime of K and T in which diffusive crack growth is

important. Results of these studies will be incorporated into crack

growth mechanism maps for ceramic materials.

Strength Degradation Maps

Strength degradation mapping provides an alternative to the pure fracture

mechanics approach for lifetime prediction. Although the approach is

probabilistic in nature, concepts of fracture mechanics can be factored

562-33
into the approach. Probabilistic concepts of strength are used for the

construction of strength degradation maps which relate strength, failure

time, and failure probability on a single diagram. These maps provide a general picture of the failure probability on a single diagram that can

be used to establish engineering loads, and temperatures that are consistent

with engineering requirements. Last year, a map of this sort was obtained

for magnesia-doped, hot-pressed silicon nitride (NC 132); this year a map was obtained for yttria-doped, hot-pressed silicon nitride (NCX 34).

A comparison of the two maps shows that the properties of NCX 34 are far

superior to those of NC 132. For a given load, the NCX 34 is capable of

operating at a higher temperature 100 °C) than the NC 132, without

long term loss in strength. Microstructural investigations suggest that

creep cavitation is not a serious problem in NCX 34, whereas it is for

the NC 132. Studies are underway, to evaluate the effect of temperature

and strength on the microstructure of these ceramics. During the coming

year, we hope to obtain strength degradation maps on several other

structural ceramics (reaction bonded Si 3 N 4 , reaction bonded SiC, hotpressed A1 2 0 3 ). The shape of the maps will be correlated with the type

of deformation and fracture occurring for each material.

Engineering Evaluation of Ceramics

Subtask 3 of Task 12122

E. R. Fuller, Jr., N. J. Tighe, S. M. Wiederhorn, S. W. Freiman,

R. S. Polvani, C. L. McDaniel, R. F. Krause, Jr., and B. R. Lawn

Extensive studies are being conducted on the strength of ceramic materials

intended for use in commercial and defense applications. Materials

being studied include: geothermal cements that will be used to line

wells that tap hot water reservoirs deep within the earth; refractories

intended for use at elevated temperatures in heat exchangers; partially

stabilized zirconia linings for adiabatic diesel engines; glass intended

for use in solar mirrors; 1 ead-zi rconate titanate ceramics for voltagepulse devices; and ceramic materials for biological applications. Work

on this subtask is often conducted at the specific request of other

government agencies.

Durability of Geothermal Well Cements

The durability of various cement compositions has been evaluated following

periods of exposure to flowing geothermal fluids from a well in the

Cerro Prieto geothermal field in Mexico. This well was provided and

operated by the Comision Federal de Electricidad, who also assisted in

the placement and retrieval of the cement samples. Sixteen cements,

which are potential candidates for cementing operations in geothermal

wells, were selected for these durability tests. Specimens were installed

both in special vessels aboveground near the wellhead and in baskets

which were lowered about 700 meters into the well at a temperature of

214 °C. Two types of specimens were used in the tests: (1) 50 mm cube

specimens which were precured for one day in an autoclave at 200 °C and

20 MPa; and (2) slurries of cement which were prepared at the wellhead,

cast into sandstone cups and cured under the exposure conditions.

Following periods of exposure of one day, three months, six months, and

one year, the durability of specimens, were evaluated by compressive

562-34
strength and water permeability measurements. The precured cubes of

many of the cements showed considerable erosion with exposure time due

to geothermal fluids, especially in the vessels aboveground where the

cubes were directly exposed to the flowing geothermal fluids. The

compressive strength of these specimens generally decreased with time

and their permeability increased. In contrast, the protected sandstonemolded cements fared better, their properties generally improving with

time. This type of protected exposure is probably more representative

of the conditions a cement would see as a well liner. Properties of the

cements were evaluated in cooperation with the Instituto de Investigaciones

Electricas, Cuernavaco, Mexico.

Polymer Concrete for Geothermal Applications

Nonmetal lie materials have a number of beneficial properties for their

application in geothermal systems (e.g., greater corrosion and abrasion

resistance and greater load-bearing capacity per weight of structure).

Offsetting these advantages are the detrimental properties of low impact

strength and fracture toughness, of time-dependent crack growth behavior

and of enhanced thermal stresses. In order to design effectively with

these materials and to utilize them in geothermal systems, the fracture

properties have to be measured for these materials and damage mechanisms

resulting from exposure to geothermal environments need to be assessed.

This year a program was begun to determine these properties for a polymer

concrete material which has been proposed for geothermal heat exchanger

pipes and pressurized vessels. Initial measurements have been made to

characterize the fracture toughness and the Charpy impact strength as a function of temperature from -20 °C up to 150 °C. Research anticipated

in the coming year include pressure-rupture tests with a characterization

of the failure mode and failure mechanisms.

Refractories for Heat Exchangers

The anticipated use of ceramic heat exchangers in numbers of new energy

systems necessitates the evaluation of the creep-rupture behavior of

refractories at elevated temperatures. The use of refractories in

regenerative heat exchangers for MHD applications, for example, requires

the creep behavior of refractories to be evaluated at temperatures as high as 1600 °C. Similarly, the use of non-oxide ceramics in recuperative

heat exchangers also requires the creep-rupture behavior of ceramics to

be evaluated at these elevated temperatures. The objective of this

study is to obtain sufficient data on potential heat exchanger materials

to make an intelligent decision on materials selection for these applications.

Two types of refractories are being included in the current program,

(a) fused-cast oxides and (b) hot-pressed and sintered silicon carbide.

Dynamic and static loads tests are being used to evaluate the high

temperature strength and long term durability of these materials. The

oxide ceramics have been used traditionally for lining glass melting

furnaces where their compressive strength and corrosion resistance are important properties. In attempting to use these materials for other

structural purposes, it is also necessary to know the high temperature

tensile strength of these materials. Five compositions of fused-cast

refractories are under test: alumina-zirconia-silica, alpha and beta

alumina, alpha alumina, chromia alumina, and chromia alumina spinel.

562-35
Alumina-zirconia-silica retained its strength up to 1100 °C when loaded

rapidly. However when slow rates of loading were used or when static

loads were applied, its strength was nearly zero at 1100 °C. The strength

of this material is limited by the failure of the glassy phase. By

contrast, hot-pressed silicon carbide exhibited little or no creep at

temperatures up to 1400 °C. The material did however exhibit a strength

loss at temperatures above ~ 1100 °C compared to the strength measured

at room temperature.

Ceramics for Diesel Engines

Recent research supported by the U.S. Army and the Department of Energy

at the Cummins Corporation demonstrated the practical value of adiabatic

diesel engines as a means of improving the thermal efficiency of these

engines. A ten percent improvement in diesel oil consumption was registered recently by the Cummins Corporation in a standard diesel engine,

which had been converted into an adiabatic engine. The conversion was achieved by coating all parts of the engine contacting hot gases with

zirconium oxide. Improved efficiency (up to 50 percent) is anticipated

with the use of either thicker zirconia coatings, or partially stabilized

zirconia inserts in the cylinder wall liners. The Department of Energy,

which is supporting this research program, has requested support from

NBS to evaluate the microstructure and the mechanical properties of

ceramic materials currently being used in the diesel engine program. As

the evaluation of these materials is consistent with our other high

temperature materials program, we have agreed to assist the Department

of Energy in this task. As part of this project, we will evaluate the

response of partially stabilized zirconium oxide to subcritical crack

growth and to thermal cycling (in the temperature range of diesel engine

operation).

Lead Zirconate Titanate Ceramics (PZT)

Lead zirconate titanate ceramics of nominal composition 95% PbZr0 3 to 5%

PbTi0 3 exhibit piezoelectric properties and are used in devices in which

a voltage pulse is required. Premature fracture of these materials

reduces the pulse length and renders the device ineffective. The reliability of the material has been noted to vary from lot to lot, depending

in a complex way on processing conditions.

The objective of this study is to determine whether the fracture toughness

of the material is a measure of the material's ability to survive more complex and expensive functional tests. It is also the aim of this

project to determine the fundamental cause for the variation in properties

from lot to lot. The effects of temperature, poling condition, and

applied electrical field on fracture are also being studied. Transmission

electron microscopy is being used to investigate microstructural variations

in materials and to understand crack tip material interactions leading

to increased toughness.

Results to date have shown that the temperature dependence of the material

in the pressure depoled condition is an indicator of the quality of the

lot. Good lots show a maximum toughness of pressure depoled material at room temperature, while in poor lots the maximum seems to be shifted to

562-36
~ -35 °C. It is hypothesized that these shifts are related to the

ability of the material at the crack tip to undergo a stress induced

phase transformation. No significant effects of electrical field, or differences in lots of material in the electrically poled condition

could be discerned. Transmission electron microscopy has shown variations

in chemical composition and microstructure from one lot of PZT to another.

A paper was presented on this work at the Annual Meeting of the American

Ceramic Society in Cincinnati, OH.

Glass for Solar Mirrors

Various glass compositions are being considered for mirrors used in

solar energy collection facilities. Since these mirrors may be subjected

to harsh weather conditions, i.e., high temperatures, rain, hail etc.,

it is important to determine their resistance to crack growth in order

to predict lifetimes and to make the best material selection.

In this project, both subcritical crack growth data using double cantilever

beam specimens and dynamic fatigue data on four point flexure specimens

was collected for three glass compositions. All data was taken in water

at room temperature. A value of the inert strength of each glass was obtained by rapid loading in dry N2 gas. The crack growth parameters

obtained from the dynamic fatigue data were used to construct design

diagrams for each of the glasses. A statistical analysis of the uncer- tainty in each of the measured crack growth parameters was used to

determine uncertainties in the predicted lifetimes.

Bioceramic Materials

Another new and interesting application of ceramic materials is in the

field of medicine. Certain types of ceramic materials (aluminum oxide,

glass ceramics) are useful as structural components of prosthetic devices

because they are biologically inert to the body environment and are relatively strong when compared with bone. Consequently, these materials

are being introduced into the body in several applications: total hip

replacements, anchors for artificial teeth, and artificial knee joints..

Given the tendency for ceramic materials to undergo stress-corrosion

cracking due to water in the environment, there is concern over the

ability of these materials to perform their function in the body environment for extended periods. Because of this concern, the Division has

been conducting a study to determine the effect of microstructure on stress-corrosion cracking of aluminum oxide.

During the past year, static and dynamic fatigue data were collected on implant grade A1 2 03

. An analysis of these data suggests that fatigue

data obtained by three-point bending may result in erroneous values of

fatigue parameters. Because three-point bending produces a considerable

stress gradient at the tensile surface, the flaw that causes the specimen

to rupture, may not be the largest flaw in the specimen. Since the

lifetime prediction equations commonly in use today all assume the

largest flaw to be the source of failure, basic assumptions of the

lifetime prediction equations are not valid when three point bending- is

used as a test method. This problem does not arise when four-point

bending test methods are used to obtain static fatigue data, because the

stress fields on the tensile surface of the specimen is uniform.

562-37
Extensive Monte Carlo computer calculations have shown that convergence

usually does not occur for trivariant regression analyses, a technique

that is often used for lifetime prediction analyses. The observation

that a number of roots are normally found from the regression analysis

precludes use of the technique to determine the "true" value of N. The

bi variant regression technique can be used, but here errors result from

uncertainties in the Weibull modulus for the material. Extensive fourpoint bend tests are underway using indentation procedures to provide

reproducible flaws for the determination of N. A paper on the current

findings was presented at the Annual Meeting of the American Ceramic

Society.

In the coming year we shall obtain more accurate measurements on aluminum

oxide using a controlled flaw approach (see Subtask 4). Vickers indenters

will be used to introduce a well-defined fracture origin, of predetermined

size, for failure. This will enable highly accurate data to be obtained.

A comprehensive fatigue test program is scheduled for determining crack

velocity parameters for the alumina. Inert strength data will be taken

on specimens with polished surface finishes to characterize the natural

flaw distribution. This approach offers the prospect of predicting

lifetime characteristics of prosthetic components with unprecedented

specimen economy, eliminating the need to take vast quantities of fatigue

data for statistical analysis.

Contact Processes in Ceramics

Subtask 4 of Task 12122

S. M. Wiederhorn, B. R. Lawn, B. J. Hockey, D. E. Roberts, and R. S. Polvani

Contact damage studies provide valuable information on fundamental

deformation and fracture properties of materials and can be used as the

basis for modelling important practical processes such as erosion, wear

and the machining of ceramic materials. During the past year, our effort

has been directed towards the development of a detailed understanding of

the fracture and plastic deformation that occurs during contact. We

currently have projects concerned with: (1) indentation damage; (2) dynamic

hardness; (3) effect of sliding contact on strength. In addition to

these three projects, we have completed our work on the erosion of

ceramic materials at elevated temperatures.

Indentation Damage

It is now recognized that ceramics can be deformed irreversibly at room temperature. Moreover, this deformations plays a dominant role in the

initiation and propagation of cracks that control the strength and wear

behavior of ceramic materials. Recognizing this fact, a considerable

effort has been made in the past few years by Dr. B. R. Lawn and his

colleagues at the University of New South Wales to understand the micromechanics of contact damage in brittle materials. With the transfer of

Dr. B. R. Lawn from the University of New South Wales to the National

Bureau of Standards, this effort has also been transferred to NBS.

During the past few years much progress has been made on the analysis of

stress fields in elastic/plastic contact. The most important finding
from these studies is the identification of the vital role of residual

stresses in the associated fracture process. These stresses have been

ignored in the ceramics testing literature, as a result of which much of

the published data relating to strength and erosion is in error.

One of the important applications of indentation analysis lies in the

evaluation of basic fracture parameters. Indentation flaws of predetermined size can be placed in strength test pieces with great control,

thereby allowing for accumulation of strength data with unprecedented

experimental simplicity and specimen economy. This gives a powerful

tool for measuring toughness and crack velocity parameters, without the'

need for statistical data manipulation. This aspect of the work is at a highly developed stage and has resulted in several publications in the

last year.

A second application is the characterization of flaws. Because the

location of the indentation flaw, as well as the size, can be predetermined, one can follow the flaw evolution to failure throughout the

entire strength test. This is a unique feature of strength analysis.

Through studies of this kind we have now established that many (probably

most) of the strength-controlling "natural" flaws in ceramics respond in an analogous manner to the indentation cracks, particularly as regards

the influence of residual stresses. Flaws introduced by particle impact,

abrasion and machining certainly fall into this category.

Dynamic Hardness

Because of the importance of hardness to the nucleation of cracks during

short term contact events in erosion and machining, an attempt is being

made to measure the dynamic hardness of ceramic materials. The method

uses an electrically driven hardness indenter and operates over several

decades of time, 10-4 to 10

4 seconds, and delivers penetration loads

between 0 and 10 Newtons. The technique is capable of developing several

different wave forms for the penetration load: (1) sinusoidal,

(2) triangle, (3) square, and (4) ramp. Current emphasis on equipment

development is directed towards the addition of a means of sensing the

displacement of the indenter as it penetrates into the sample. This

will be accomplished through the use of electronic transducers.

Experimental studies during the past year have been carried out on soda-lime silica glass, copper, and tungsten using sinusoidal impulse

loads. As the period of impulse decreased from ~ 10 4

s to 10-2

s the

hardness of these materials was found to increase by ~ 10 percent for

copper and glass, and by ~ 20 percent for tungsten. A short note discussing

this work has been accepted for publication by the Journal of Materials

Science. We have also observed that the duration of load has significant

influence on the threshold for crack formation in glass. During the

coming year the effect of load duration on fracture will be studied

extensively.

Effect of Sliding Contact on Strength

This area of work for the Division is intended to enhance our understanding

of contact damage in structural ceramics at elevated temperatures. The

562-39
data obtained on this project will be used for the assessment of theoretical treatments of strength degradation caused by sliding contact stresses.

During the past year, equipment has been constructed to measure the

adhesive and frictional forces that develop between ceramics at elevated

temperatures. Tests have been conducted on glasses to determine the

temperatures at which the friction is enhanced as a result of adhesion

at the contact interface. Studies indicate that the coefficient of

friction increases precipitously at a temperature of ~ 200 °C below the

fictive temperature. This increase in friction requires the application

of both a normal and tangential load at elevated temperatures, since

tests on glass indicate that adhesion does not occur at stresses less

than the fictive temperature. Microscopic examination of the contact

interface indicates a pronounced effect of temperature and load on the

type of fracture damage that occurs as a result of contact. Plans are currently underway to evaluate the effect of the fracture damage on strength.

Microstructure of Ceramics

Subtask 5 of Task 12122

B. J. Hockey and N. J. Tighe

The objective of this subtask is to evaluate the effect of microstructure

on the mechanical properties of ceramics. Scanning and transmission

electron microscopy are the principal techniques used in this task.

During the past year, work was directed at (1) uses of analytical microscopy, (2) crack tip deformation, (3) microstructural analysis of PZT.

Analytical Microscopy

The analytical capabilities of the scanning transmission electron microscope has been used to evaluate (a) ceramics that were deformed at high

temperatures and (b) thin ceramic films that were made by electron beam

evaporation. Oxide and non-oxide ceramics such as alumina-zirconia,

silicon nitride, and silicon carbide were deformed during static load

tests and their microstructural characteristics were identified and

categorized. Surface and near surface features such as oxidation pits,

grain boundaries, cavities and cracks were examined using secondary

electron imaging and transmission diffraction contrast imaging. Inclusions

and precipitates were imaged using back-scattered electrons and identified

chemically and structurally using dispersive X-ray analysis and electron

diffraction analysis. The surface microstructure was correlated with

the sub-surface microstructure. This analysis was used to identify and

characterize the deformation mechanisms that occur in ceramic materials

at elevated temperatures.

Thin Films

Thin evaporated films of zirconia and magnesia are being evaluated in

o collaboration with Dr. Farabaugh of Division 561. Films, 250 to 750 A, were grown on cleaved mica substrates and carbon coated for examination

in the STEM. The crystallinity and composition of the films were determined as a function of thickness and deposition parameters. This type

562-40
of film will be used in reference standards for electron energy loss

spectroscopy (EELS) and energy dispersive X-ray analysis (EDX) in the

STEM instrument.

Crack Tip Deformation

In this effort, transmission electron microscopy (TEM) is used to define

the specific role of plastic deformation during fracture. Emphasis is

placed on identifying the mechanisms of dislocation emission from cracks,

and in relating the nature and distribution of dislocation to current

fracture criterion models.

In MgO, TEM examination has recently confirmed the occurrence of plastic

deformation during controlled crack propagation. Dislocation loops are seen to emerge not only from the vicinity of arrested crack tips, and

are also found along the crack path. Preliminary analysis indicates

that these dislocations do not lead to significant physical blunting of

the crack tip. The results support recent "crack tip shielding" models,

in which dislocation emission acts solely to reduce (or "shield") the

stresses acting on a fully brittle crack. At present, a complete analysis

of these crack tip dislocations and their dependence on crack orientation

is being conducted. The analysis will allow a definitive interpretation

of the effect of deformation on fracture.

Further work will include an effort to determine whether dislocation

emission originates at the actual crack tip or from internal sources

located in the vicinity of the crack tip. Similar TEM studies will be

made on silicon, and will include the effect of temperature.

Microstructural Analysis of PZT

Two commercial forms of lead-zirconia titanate were examined using the

CMS Philips 400 TEM/STEM analytical electron microscope. . While similar

in composition (PbZr03 to 5% PbTi03 ), the two forms were processed

differently and were found to possess different mechanical properties,

i.e., strength and fracture toughness.

Examination showed that both polycrystalline materials were reasonably

similar with regard to: grain size, shape, and distribution; porosity;

defect and domain structure; and minor impurity content. Consistent

with phase diagram data, the major phases were ferroelectric with rhombohedral structures (several variants were identified).

A significant difference between the two forms, however, was found in

the nature and distribution of grain-boundary phases. In the tougher,

higher strength material, grain-boundary phases were inhomogeneously

distributed (generally, being located near large voids or inclusions).

In this material, the grain boundary phases were invariably crystalline

and contained both A1 and Si as major impurities. Conversely, the lower

strength material contained a more uniform distribution of grain boundary

phases, which were typically low density (porous) amorphous structures.

While these amorphous structures were not identified, they generally

contained either A! and Si or Si alone as major impurities.

562-41
While the results clearly indicate a relationship between mechanical

properties and grain-boundary structure, which in turn can be related to

processing technique, little information was provided on the actual

processing treatments used in producing the two PZT materials.

Engineering Evaluation of Composites

Subtask 6 of Task 12122

M. B. Kasen, R. E. Schramm, R. D. Kriz, H. M. Ledbetter, and C. M. Fortunko

Nonmetal lies Property Determination and Modeling

Elastic properties, such as Young's modulus and the related property,

internal friction, are fundamental to characterizing and understanding

filamentary-reinforced composite materials. Several theoretical and

experimental studies are in progress: (1) relationships between microscopic (constituent) properties and macroscopic (composite) properties

in a cooperative program with the University of Colorado using theories

based on scattered plane waves that predict sound velocities and elastic

constants; these theories will be extended to ultrasonic attenuation,

having been tested successfully for boron-aluminum and graphite-epoxy;

(2) detection of mechanically induced damage; experiments show that the

Young's modulus in graphite-epoxy can either decrease or increase depending

on the deformation mechanism while internal friction always changes

oppositely; (3) relationship between static and dynamic elastic constants

using theory and experiment to clarify this frequently confusing corres- pondence; (4) internal friction of interfaces, just beginning, will

probe the interrelationship among three sources of internal friction--f i 1 ler,

matrix, and interface; and (5) stress- induced interface strains in

crossply laminae where misaligned anisotropic connected layers have

strongly anisotropic interfacial strains that have been calculated from

the full set of elastic constants.

We now focus on two particular problems:

(1) Ultrasonic determination of complete nine-component (orthotropic)

elastic-constant tensor for a glass-fiber-cloth-reinforced composite.

Equipment for room-temperature elastic-constant measurements of Young's

and torsional moduli is in place and operating. Calibrations are in

progress. This equipment consists of a Marx three-component oscillator

where two components are identical quartz piezoelectric crystals. The

specimen is the third component. This equipment operates at near-zero

stress amplitude in the kHz region. Therefore, one obtains the highfrequency, adiabatic, elastic constants.

(2) Local stress in a woven-composite unit cell. A finite-element

program used to predict regions of high stress within a unit structural

cell is available. Element library includes constant-strain triangles

modeled for nonzero out-of-plane strain with isoparametric nonzero out-of-plane element with orthotropic elastic properties.

Thermal properties, such as conductivity, are of fundamental importance

in designing efficient thermal standoffs transitioning from 295 K to 4 K

562-42
in cryogenic systems. Very low conductivities make it difficult to

obtain accurate measurements, and in the past, results from different

laboratories were at variance. A series of studies was therefore undertaken to determine the extent to which variables such as resin content,

strain effects, and specimen thickness affected the measured conductivities

of G-10CR glass-reinforced epoxy laminates from various manufacturers,

G-11CR, and a European laminate similar to G-10. Specimen strain at room temperature was found to have an insignificant effect, thickness

differences produced detectable but negligible conductivity variations,

while variations in resin content had a large effect. An equation

derived from a conductivity model in which the glass and resin thermal

resistances are added in proportion to their volume fractions was found

to predict conductivities in good agreement with the experimental data.

Radiation Effects on Nonmetallics

Insulators for superconducting magnets used in fusion technology must

continue to function after exposure to neutron and gamma irradiation at

4 K. Thus far, G-10CR and G-11CR laminates have been screened for such

performance by ORNL, as has a variant of G-10CR in which the epoxy

matrix was replaced by a polyimide. NBS provided the basic cryogenic

mechanical performance data in the unirradiated state for each of the

test materials. It is expected that research to develop functional,

cost effective laminate systems for this service will accelerate in the

coming year, with close cooperation between national laboratories,

universities, and laminating firms beginning work in the area. The wish

to cooperate in this effort has also been expressed by individuals

representing laboratories in Japan, England, and Germany.

562-43
.

.

.

.

.
ELASTIC-PLASTIC FRACTURE MECHANICS

Task 12123

Safety and durability are primary considerations in the design and

construction of engineering structures. Sophisticated methods to assess

structural safety and durability have been developed on the basis of

linear-elastic fracture mechanics. These analytical methods are applicable

to the high-strength alloys used for aerospace vehicles and to the

heavy-section steels used for nuclear pressure vessels. Unfortunately,

the methods of linear-elastic fracture mechanics do not apply to a wide

range of metal structures, including bridges, pressure vessels, ships,

offshore structures, and pipelines, because in these applications, the

materials of construction (steels and aluminum alloys are typical) are highly plastic (nonlinear) before fracture. Consequently, the assessments

of structural safety and durability are based on empirical methods and

prior experience. Although current methods usually provide a reasonable

record of structural safety, improved efficiency and productivity could

be achieved if more rational methods were used to establish material

toughness requirements, allowable stress levels, minimum service temperatures, and weld-quality standards. The objective of this task is to

establish the scientific basis (i.e., elastic-plastic fracture mechanics)

for developing fracture-prevention procedures applicable to materials

that exhibit extensive plasticity.

Fracture Mechanics Relationships

D. T. Read, H. I. McHenry, R. B. King, and Y.-W. Cheng

The application of elastic-plastic fracture mechanics to the assessment

of structural safety hinges on the development of analytical relationships

among applied strain, required toughness, and flaw size. The approach

used to establish such a relationship for the elastic-plastic case is to

measure the driving force for fracture as a function of strain in tensile

panels with a given flaw size and configuration. The driving force for

fracture is measured in terms of the J-contour integral (J) or the crack

tip opening displacement (CTOD). If one assumes that fracture occurs when a critical value of J or CTOD is reached, then the measured driving

force is the same as the required toughness. Thus, each test results in an empirical relationship among applied strain, flaw size, and required

toughness that is directly applicable to the specimen configuration.

Tests are being conducted on a variety of specimen flaw configurations

to provide a data base to evaluate critically the theoretical models and

finite element analysis methods of relating applied strain, required

toughness, and flaw size.

Procedures for the direct measurement of J are based on the definition

of the J-integral

J = W dy - f -au/ax ds (1)

where W is the strain energy density, f is the traction vector, u is the

displacement vector, x and y are Cartesian position coordinates, and s is arc length along the contour, T. A convenient contour for evaluating

J follows free surfaces along the y direction and traverses the tensile

562-45
axis at a location remote from the crack. Measurement of the J- integral

along this contour requires determination of the strain energy density

along the y-direction contour segments and measurement of traction and

displacement vectors along the x-direction segments. The strain-energy

density is obtained using strains measured along the contour and the

stress-strain curve of an uncracked tensile panel. The y-components of

-the traction and displacement vectors along the x-direction contour

segments are measured using strain gauges and LVDTs, respectively. The

change in displacement with position, du/dx, is calculated from the

measured displacements. During a typical test, approximately one hundred

J-vs-6 data points are obtained. Each point is computed from about

twenty-five measured values of strain, displacement, and load.

The J-contour integral has been measured as a function of strain, e, for

HY 130 steel plates using several specimen configurations. The results

indicate that the functional form of the dependence of J on strain is

usually parabolic, then linear. The parabolic region at low strains is

the region of linear-elastic fracture mechanics. The slopes of the

linear parts of the J-vs-c curves depend on crack length. As the crack

length decreases to low values, deformation changes from net section

yielding to gross section yielding, and the slope of the J-vs-e plot

decreases sharply. A design curve has been developed to relate required

toughness, flaw size, and strain for the case of gross section yielding.

Finite element analyses have been conducted to calculate J-vs-e for

comparison with the experimental results on HY 130 plates. Analyses

that assumed plane stress overestimated the measured values of crack

mouth opening displacement (CMOD) and J; yet excellent agreement was observed with the experimental load-displacement and limit-load results.

The discrepancy was attributed to through-thickness constraint. Threedimensional modeling of the crack tip region is being developed to

account for constraint effects.

The demonstrated usefulness of the J-integral as a measure of the driving

force for fracture and as a fracture criterion for two-dimensional

configurations makes it desirable to apply J in a similar fashion to

three-dimensional configurations such as surface flaws. Recent research

at NBS has demonstrated that the J-integral for line contours about

part-through cracks is path independent for two special planes. These

planes are the planes of symmetry for part-through cracks and include

the plane of maximum depth of a semielliptical surface flaw. Thus, the

point of maximum J along the front of a surface flaw can be evaluated

using the line J-contour integral.

Given that J is path independent for the plane of symmetry of a surface

flaw, it is possible to measure J-vs-e using the procedures described

previously. For a surface flaw centered with respect to width and

length in a tensile panel, the measurement contour is in the center-width

plane and extends from the crack plane up the front face of the specimen,

through the thickness, and down the back face of the specimen to the

crack plane. A series of surface-flawed tensile panels of API 5LX-70

pipeline steel weldments were instrumented and tested to measure J and

crack opening displacement (COD) vs e.

562-46
The experimental results of J (and COD) vs e were compared with analytical

results obtained using the line-spring model. In this model, the surface

flaw is treated as equivalent to a through- thickness flaw of the same length that is subject to closure forces and moments due to the presence

of the uncracked ligament. The closure forces are computed by balancing

the forces and moments such that the COD of the through- thickness crack

is compatible with the COD of an edge-cracked panel with the same thickness

and crack depth as the surface-flawed panel. The ligament is treated as an elastic, perfectly plastic spring, and thus, the magnitude of the

closure forces and moments remains constant after ligament yielding.

The elastic, perfectly plastic spring and the constant-depth crack

assumptions result in considerable simplification of the analysis,

thereby avoiding the necessity of computerized numerical methods. The

excellent agreement between the experimental and analytical results from

both COD and J suggests that the simplifying assumptions are reasonable

and that a useful and convenient method for surface-flaw calculations is

available.

Fracture Toughness

H. I. McHenry, I.-H. Lin, J. G. Early, Jr., and R. B. King

In elastic-plastic fracture mechanics, fracture toughness is generally

measured in terms of J or CTOD. As currently measured, fracture toughness

is not a geometry-independent material property for steels in the transition region between linear-elastic and fully ductile fracture. The

critical values of J or CTOD depend on the three-dimensional stress-strain

behavior in the vicinity of the crack tip, i.e., on the crack tip region

constraint (CTRC). Available information indicates that CTRC is a function of geometry, type of loading, and strain hardening. Thus, a predictive fracture criterion for the elastic-plastic case should be

proportional to a material property, such as the plane strain fracture

toughness, Kj

c

, and should be scaled by a function of CTRC.

A study of fracture-characterizing parameters addresses the influence of

CTRC on observed fracture behavior. Especially large errors can be

introduced by present measurements of critical J-integral or CTOD values

for the onset of cleavage fracture; large measurement variations are due

to differences in CTRC between laboratory test specimens and cracks in

structures. For example, the critical values of J or CTOD obtained in

deeply notched single edge-notched bend (SENB) specimens may grossly

underestimate the toughness associated with identical material at the

tips of smaller SENB specimens or at shallow surface cracks in large

structures. Although published research indicates a growing awareness

of these situations, there appears to be no generally acceptable method

available at this time to determine the magnitude of the CTRC. The

approach being taken is to obtain a comprehensive set of elastic-plastic

fracture data (both J and CTOD) on a C-Mn steel for specimen designs

having a wide range of plastic constraint. These data demonstrate

geometry dependence and establish an empirical basis for developing a parameter to characterize the influence of plastic constraint.

A theoretical study of cleavage fracture is being conducted to complement

the empirical studies. A model is being developed that is an extension

562-47
of the work of Ritchie, Rice, and Knott. It uses the strain-field

solutions of Hutchinson to predict stress-state effects on the brittle-toductile fracture-mode transition. The experimental data will be used to

evaluate the resulting theoretical predictions. In addition to plastic

constraint effects, metallurgical factors are being investigated, particularly grain-size effects.

As part of a program to formulate guidelines and procedures for the

inspection of pipeline girth welds, a fracture mechanics approach has

been chosen to evaluate and assess allowable girth weld flaw sizes. The

fracture toughness of the weld metal and associated HAZ are needed

parameters in the criteria for accepting or rejecting a weld flaw.

Crack-opening displacement (COD) tests were carried out on both weld

metal and the HAZ from API 5LX-70 linepipe girth welds over the temperature

range of -150 °F to +75 °F to establish the temperature dependence of

the crack tip opening displacement (CTOD) toughness parameter. Using

the fracture toughness temperature dependence data, a multiple specimen

resistance curve approach was used to determine the critical crack tip

opening displacement for the initiation of stable crack growth at the

lowest temperature at which reproducible slow stable crack growth occurred.

Some preliminary data were taken on the effect of specimen pretreatment

to control fatigue crack shape on the measured fracture toughness.

A program to develop materials selection criteria for crack arrester

strakes has been initiated. The objectives of the program are to develop

experimental methods sufficient to thoroughly characterize the crack

arrest event under conditions where extensive plastic deformation contributes to arrest, and to develop crack arrest criteria for the case of a crack that initiates in a low toughness plate and propagates through a weld into a crack arrester plate. Initial tests have been conducted to

develop the necessary instrumentation.

A program has been started to assess the significance of fatigue cracks

detected in offshore structures during in-service inspections. The

objectives of the program are to investigate the fatigue crack growth

behavior of surface cracks in steel weldments under simulated service

conditions, to analytically model the growth of surface cracks under

variable amplitude loading, and to compare the analytical predictions

with the experimental results. Fulfillment of these objectives should

provide the technological basis for deciding what remedial actions

should be taken in the event that a fatigue crack is discovered during

in-service inspection of offshore structures.

Significance of Defects

H. I. McHenry, M. B. Kasen, and Y.-W. Cheng

A program has been completed establishing preliminary weld-quality

requirements for the Alaska Natural Gas Transportation System (ANGTS).

Analytical studies involved modeling of the significance of defects

using methods comparable to those used for the trans-Alaska pipeline

assessment conducted previously. Experimental studies involved the

measurement of CMOD as a function of remote strain for tensile panels

with surface flaws. The results of these experimental and analytical

562-48
studies validate the critical COD models used in the trans-Alaska oil

pipeline. These models have been used to establish the allowable flaw

size curves and their sensitivities to applied stress, and material

tensile flow properties were compared and evaluated.

The extent to which the through-wall dimension of typical weld flaws,

such as porosity and slag, is limited by the depth of a weld pass was studied in pipeline girth welds. Confirmation of such an inherent

limitation simplifies the application of fracture mechanics principles

to welds inspected by conventional radiography. Both multi axis radiography

and serial sectioning were used in this work.

The probability of fracture initiating from blunt pipeline girth weld

flaws was assessed in a program that subjects weldments containing slag,

porosity, and arc strikes to low-cycle, strain-controlled, fully reversed

fatigue within the plastic range. Results indicate that such flaws have

a very low probability of initiating failure in weld metal of the toughness

used in pipeline construction. The results are supportive of the concept

that the allowable content of such flaws is more properly established on the basis of the percentage obscuration of a radiographic film than on flaw dimensioning.

Ultrasonic and Electromagnetic Techniques for Nondestructive Evaluation

and Characterization

C. M. Fortunko, M. Linzer, S. J. Norton, A. H. Kahn, and R. E. Schramm

During FY 1982 significant advances were made in four areas: (1) non- contact evaluation of butt weldments; (2) noncontact measurement of

in-plane residual stresses in plates; (3) eddy current characterization

of sharp surface flaws; and (4) theoretical development of ultrasonic

imaging techniques. In areas (1) and (2) use was made of special ultrasonic probing signals that can only be generated and detected using

electromagnetic-acoustic transducers (EMATs). The special ultrasonic

signals are shear waves polarized parallel to the surface of a plate

(shear horizontal or SH waves). In area (3) a new high-frequency eddy

current probe was developed to permit measurements of surface flaw

responses over a two-decade frequency range (100 kHz to 20 MHz).

In the area of ultrasonic imaging, significant progress has been made in

the, areas of theoretical development of new ultrasonic techniques for

characterization of material properties and detection of flaws in weldments. A new program was also initiated in the area of acoustic emission

(AE) technique development using laser generation and detection.

In the area of weld inspection, three separate projects were carried

out: (1) definition of inherent flaw sizing accuracy limitations for

inspection of pipeline girth welds; (2) development of improved techniques

for in-service monitoring of intergranular stress corrosion cracking in

nuclear power plants; and (3) definition of a special noncontact SH-waveEMAT inspection system for the U.S. Navy. The work in the area of weld

inspection was carried out in collaboration with Professor S. K. Datta

of the University of Colorado in Boulder, Dr. R. K. Elseley of the

Rockwell International Science Center, Dr. B. W. Maxfield of the Lawrence

562-49
Livermore National Laboratory, and Mr. Marvin Fleming, a subcontractor

to the Electric Power Research Institute. In addition, close relationships were maintained with other centers Of research (Battel le-Northwest

Laboratories, Iowa State University, and Johns Hopkins University) in

the area of nondestructive evaluation of welds. Several industrial

liaisons were also maintained.

In the area of ultrasonic residual stress measurement, a significant

advance was made by demonstrating that the in-plane residual stresses

can be determined ultrasonically in elastically anisotropic and inhomogeneous engineering alloys. Specifically, it was shown that the influences

of stress and material property variations on the ultrasonic velocities

can be separated. To accomplish this, a new theory was developed to

relate the velocities of obliquely propagating SH-waves to in-plane

stresses and weak anisotropies caused by microstructural effects. The

efficacy of the technique was then demonstrated using a specially designed

SH-wave-EMAT system. This work was carried out in very close collaboration

with Dr. R. B. King, also of the Fracture and Deformation Division.

In the area of eddy current characterization of surface flaws, a large

number of experimental measurements were carried out in support of the

theoretical work carried out by Professor B. A. Auld at Stanford University.

A considerable in-house theoretical effort was also conducted. As a part of the experimental effort, a novel eddy current probe design was developed, and a large number of calibrated experimental samples were

prepared. As a consequence, it was possible to verify that the phases

of eddy current flaw responses carry important information about the

flaw depth and shape when the effects of nonuniform probe fields and

electromagnetic interferences are taken into account. It is hoped that

future extensions of the present work will lead to significant advances

in probe design and calibration, and will help to open-up the field of

eddy current imaging.

In the area of ultrasonic imaging (4), the work during FY 1982 emphasized

the theoretical development of new ultrasonic imaging techniques. A

perturbation method for correcting for ray refraction in velocity and

attenuation tomography has been devised. This work will allow the

practical generation of more accurate images of ultrasonic parameters

and hence better characterization of materials properties. An imaging

system based on an annular aperture has also been developed. The approach

provides a reflectivity image with resolving power equivalent to that of

a full circular aperture twice the diameter of the annulus. This, in

turn, permits more economical and rapid imaging over a smaller area of a material surface.

New programs were initiated in the areas of technique development to

(1) improve the accuracy and sensitivity of acoustic emission (AE)

measurements, and (2) develop a laser-based ultrasonic remote sensing

technique. In addition, work was begun on a computer-based, low-frequency

ultrasonic imaging system using SH-wave electromagnetic-acoustic transducers as array elements. This work is a part of a multi-year program

in cooperation with the Defense Advanced Research Projects Agency and ' the U.S. Navy.

562-50
Low-Temperature Properties

R. P. Reed, R. L. Tobler, H. I. McHenry, J. M. Arvidson, and N. J. Simon

A major developing technology is the use of superconducting magnets in

energy applications. High magnetic fields are required for fusion-plasma

and MHD-plasma confinement and guidance. Superconducting machinery,

under prototype development, provides the potential for better performance

coupled with lighter weight and reduced space requirements. Energy

storage, using large superconducting rings, is being considered. In all

applications, the magnet or superconductor, with appropriate structural

supports, is expected to operate at liquid-helium temperature (4 K) up

to 30 years.

Such emphasis on liquid-helium design and material use has led to large

national materials programs sponsored by DARPA and DOE and managed by

this NBS Division. These programs have produced a 1 ow- temperature

materials handbook; mechanical, thermal, electrical, and magnetic characterization of economical structural alloys including austenitic stainless

steels, aluminum alloys, and superalloys; an annual Low-Temperature

Materials Workshop held each October in Vail, CO; and joint research

programs with subcontractors, which have included Battelle, Westinghouse,

General Electric, Martin-Marietta, Teledyne-McKay , Alcoa, Armco, ESCO,

and Japanese steel companies. Major research emphasis has been to

characterize the austenitic stainless steels (AISI 304, 316, and 310

grades), to develop reliable welding processes and filler metals for

welding steels, and to develop stronger, tougher austenitic stainless

steels for use at low temperatures.

We are developing and characterizing a new class of austenitic stainless

steels. Interstitial strengthening of a conventional austenitic Fe-Cr-Ni

alloy is achieved by adding nitrogen, and increased alloy formability

and nitrogen solubility limits are achieved by adding manganese. We are studying the influence of nitrogen and manganese on the temperature

dependence of the flow strength, activation energies and volume, martensitic

transformations, fracture toughness, and fatigue-crack-growth rates from

room temperature to 4 K. Results indicate that the dependence of flow

strength on nitrogen concentration increases dramatically at low temperatures. Nitrogen additions suppress martensitic transformations. A

linear relationship between fracture toughness (from J-integral measurements) and tensile yield strength at 4 K has been identified. The

temperature dependence of the flow strength is critically dependent on austenite stability; low austenite stability results in strai n-i nduced

martensite formation, which produces low flow strength. The anomalous

stress-strain behavior resulting from martensite transformation has been

analyzed and reported.

The role of low ferrite and small grain size in improving low temperature

weldment fracture toughness is being studied. Crack propagation studies

at 4 K through duplex ferrite-austenite cast structures has identified

the application of an Ashby composite model for prediction of fracture

properties.

562-51
Elastic Deformation Phenomena

H. M. Ledbetter and M. W. Austin

Our effort on solid-state elastic constants comprises three categories:

(1) measurements; (2) analysis, correlations, theory; and (3) theoryobservation.

s Our measurement studies deal with metals and alloys, composites (both

fiber and particle reinforced), resins, and polymers. Many of these

materials we study versus temperature down to four kelvins. Ongoing

studies include: (1) beryllium; (2) NbTi/Cu superconductive wire;

(3) SiC-reinforced aluminum; (4) Mn-alloyed stainless steels; (5) carboncarbon composite; (6) stainless-steel welds (including some containing

delta ferrite); (7) delta-ferrite castings; (8) particle-reinforced

aluminum; (9) glass-fiber-epoxy; (10) graphite-epoxy; (11) polymethyl

methacrylate; (12) epoxy resins; and (13) several polymers.

Analytical-correlational-theoretical studies in progress include:

(1) error propagation during elastic-constant matrix inversion, for both

cubic symmetry and hexagonal symmetry; (2) calculations of Debye characteristic temperatures from single-crystal elastic constants; (3) graphical

representations of various elastic-constant surfaces; (4) prediction of

single-crystal elastic constants for stainless steels from polycrystalline

elastic constants; (5) prediction of upper and lower elastic-constant

bounds of textured aggregates and application to stainless-steel welds;

(6) modeling of periodically laminated composites; (7) modeling of an inhomogeneous NbTi/Cu composite superconductive wire; calculations of

elastic-wave surfaces for anisotropic, especially orthorhombic- symmetry

media.

In-progress theory-observation studies include: (1) in collaboration

with S. K. Datta, a scattered-plane-wave theory for predicting macroscopic

elastic constants of fiber-reinforced composites, including the anisotropicfiber case, and application to boron-aluminum and graphite-epoxy; (2) in

collaboration with S. K. Datta, a theory for predicting elastic constants

of a ring- layered composite and application to NbTi/Cu superconductive

wire; and (3) in collaboration with S. K. Datta, theories are being

developed for predicting properties of particle-reinforced composites.

This latter theory, based on plane-wave scattering will be quite powerful.

It will include eight variables: particle properties, matrix properties,

overall particle volume fraction, volume fraction of matrix "islands,"

particle shape, "island" shape, particle size, "island" size.

562-52
Other Activities of the

Fracture and Deformation Division

Invited Talks

Preliminary Evaluation of LNG Storage Tank at Salem, Massachusetts

Expert Testimony presented at Department of Transportation Hearing

Cambridge, MA

J. H. Smith

July 1, 1981

Effect of Deformation on the Fracture of Si 3 N4 and Sialon

2nd NATO Advanced Study Institute on Nitrogen Ceramics, Sussex

University, Falmer, England

R. J. Fields, T.-J. Chuang and E. R. Fuller, Jr.

July 27-August 7, 1981

Lattice Theory of Fracture

18th Annual Meeting, Society of Engineering Science, Inc., Brown

University, Providence, RI

R. M. Thomson and E. R. Fuller, Jr.

September 1981

Atomistic Aspects of Brittle Fracture

Ceramic Engineering Seminar, New York State College of Ceramics at

Alfred University, Alfred, NY

E. R. Fuller, Jr.

October 1, 1981

Stainless Steel Weld Inspection

NBS-DOE Workshop, Vail, CO

C. M. Fortunko

October 6, 1981

Fitness- for- Service

NBS-DOE Workshop, Vail, CO

D. T. Read

October 6, 1981

Review of Low Temperature Structural Alloy Research

NBS-DOE Workshop, Vail, CO

R. P. Reed

October 7, 1981

Stainless Steel Properties

NBS-DOE Workshop, Vail, CO

R. L. Tobler

October 7, 1981

562-53
Dynamic and Static Young's Moduli of Fiber-Reinforced Composites

NBS-DOE Workshop, Vail, CO

H. M. Ledbetter

October 7, 1981

Applied J-Integral Values in Tensile Panels

Second International Symposium on Elastic-Plastic Fracture Mechanics,

Philadelphia, PA

D. T. Read

October 7, 1981

Structural Material Low Temperature Mechanical Properties

NBS-DOE Workshop, Vail, CO

R. P. Reed

October 8, 1982

Mechanical Properties of CF8M Stainless Steel Castings at 4 K

NBS-DOE Workshop, Vail , CO

T. A. Whipple

October 8, 1981

Handbook of Structural Materials for Superconducting Magnets

NBS-DOE Workshop, Vail, CO

N. J. Simon

October 8, 1981

J Integral Analysis of Surface Flaws in Pipeline Steel Plates

Second International Symposium on Elastic-Plastic Fracture Mechanics,

Philadelphia, PA

R. B. King

October 8, 1981

Application of Fracture Mechanics to a Regulatory Problem

ASME-ASNT Symposium on NDE Reliability, Atlanta, GA

J. H. Smith

October 12, 1982

Subcritical Crack Growth Mechanisms in Ceramics

American Ceramic Society, Basic Science Division, Louisville, KY

S. M. Wiederhorn

October 12, 1981

Fracture Criteria for Sharp Cracks

Fall Meeting of The Metallurgical Society of AIME and Materials

Science Division of American Society Metals, Louisville, KY

R. M. Thomson and E. R. Fuller, Jr.

October 12-15, 1981

A Long Wavelength Ultrasonic Technique for Detecting and Sizing

Weld Defects

American Society for Nondestructive Testing, Atlanta, GA

R. E. Schramm

October 13, 1981

562-54
Sizing of Surface Cracks Using SH Waves

1981 Ultrasonics Symposium, Chicago, IL

C. M. Fortunko

October 14, 1981

Improvements in Flaw Detection and Sizing in Austenitic Stainless

Steel Weldments

1981 Ultrasonics Symposium, Chicago, IL

C. M. Fortunko

October 14, 1981

Preparation of Ferrous Scrap Samples for Round Robin Testing

ASTM, St. Louis, MO

J. G. Early

October 1981

Atomistic Aspects of Brittle Crack Propagation

Materials Engineering Science Seminar, Virginia Polytechnic Institute

and State University, Blacksburg, VA

E. R. Fuller, Jr.

November 10-11, 1981

Ultrasonic Nondestructive Evaluation of Girth Welds Using Electromagnetic

Acoustic Transducers

The Welding Institute, Cambridge, England

C. M. Fortunko

November 14, 1981

Ultrasonic Nondestructive Evaluation of Girth Welds Using Electromagnetic

Acoustic Transducers

AERE- Harwell , Oxford, England

C. M. Fortunko

November 16, 1981

Use of Conservation Integrals to Fracture Mechanics With Emphasis

on Application of the J Integral to Assessment of Surface Defects

The Welding Institute, Cambridge, England

R. B. King

November 16, 1981

Inspection of Stainless Steel Welds Using Horizontal Shear Waves

Institut fur Zerstorungsfreie Prufverfahren, Saarbrucken, Germany

C. M. Fortunko

November 16, 1981

Fi tness-for-Purpose Research at the National Bureau of Standards

Fitness for Purpose Validation of Welded Constructions, London,

England

R. B. King

November 17, 1981

562-55
Fracture Toughness of Steel Weldments for Arctic Structures

U. S. Geological Survey Research and Development Seminar, Baltimore, MD

H. I. McHenry

November 18, 1981

Elastic Plastic Fracture Design Curves

ASME Winter Annual Meeting, Washington, DC

H. I. McHenry

November 18, 1981

The Effect of Delta-Ferrite on the Mechanical Properties of Stainless

Steel Welds at Cryogenic Temperatures

American Society for Metals, New Orleans, LA

T. A. Whipple

November 18, 1981

Fitness-for-Purpose Research at the National Bureau of Standards

AERE-Harwel 1 , Oxfordshire, England

R. B. King

November 20, 1981

Screw Dislocation Screening and Fracture Criterion on Mode III

Sharp Curve

1981 New Orleans Topical Conference on Deformation, Fracture, Wear,

and Nondestructive Evaluation of Materials: Physics and Practice,

New Orleans, LA

I. -H. Lin

November 23, 1981

Ultrasonic Nondestructive Evaluation of Girth Welds Using ElectromagneticAcoustic Transducers

British Gas Research and Development Division, Northumberland,

England

C. M. Fortunko

November 23, 1981

Atomistic Aspects of Brittle Cracking and Crack-Tip Chemistry

Fall Meeting of American Physical Society, Topical Conference on Applications of Physics: Deformation and Fracture, New Orleans, LA

E. R. Fuller, Jr.

November 23-24, 1981

Ultrasonic Nondestructive Evaluation of Girth Welds Using ElectromagneticAcoustic Transducers

Krautkramer GMBH, Cologne, Germany

C. M. Fortunko

November 24, 1981

Nonmetal lie Composite Applications in Advanced Energy Systems

University of Illinois, Urbana, IL

M. B. Kasen

December 4, 1981

562-56
Fitness-for-Service of Pipeline Girth Welds

NBS/DOT Workshop on Pipeline Girth Weld Standards, Boulder, CO

R. P.. Reed

December 9, 1981

Detection and Sizing of Cracks Using Electromagnetic-Acoustic

Transducers

Case-Western Reserve University, Cleveland, OH

, C. M. Fortunko

December 16, 1981

Lifetime Predictions for Brittle Materials

Southwestern Section, American Ceramic Society, Albuquerque, NM

S. W. Freiman

December 1981

Ultrasonic Detection of Cracks Using Low Frequency Non-Contact

Transducers

Materials Advisory Committee: Non-Destructive Evaluation of Railroad

Wheels, Pueblo, CO

C. M. Fortunko

January 5, 1982

Ship Steels for Improved Productivity

AIME Annual Meeting, Dallas, TX

H. I. McHenry

February 16, 1982

The Effect of Delta-Ferrite on the Low Temperature Plastic Deformation

of Austenitic Stainless Steels

AIME Annual Meeting, Dallas, TX

T. A. Whipple

February 18, 1982

Stress Corrosion in Brittle Materials

Seminar at Rutgers University, New Brunswick, NJ

S. W. Freiman

February 1982

The Establishment of Low Temperature Codes and Standards

Metal Properties Council, Philadelphia, PA

R. P. Reed

March 4, 1982

Monitoring Stiffness Degradation in Graphite/Epoxy Composites

1982 ASNT Spring Conference, Boston, MA

R. D. Kriz

March 24, 1982

Interim Round Robin Ferrous Scrap Test Data

ASTM, Williamsburg, V

J. G. Early

March 1982

562-57
Microdeformation Behavior of Beryllium

J0W0G-82 Be Exchange at Rocky Flats National Laboratory, Rocky

Flats, CO

R. S. Polvani, C. S. Tilghman, and B. W. Christ

April 19, 1982

EMAT's - A New Ultrasonic Noncontact Testing Technique

Drexel University, Ultrasonic Seminar Series (G680-27),

Philadelphia, PA

C. M. Fortunko

April 21, 1982

Creep Cavitation in Non-Uniform Stress Fields

Graduate Seminar, Department of Mechanical Engineering and Mechanics,

Lehigh University, Bethlehem, PA

R. J. Fields

April 31, 1982

Equivalency of Foreign and Domestic Material Specifications for

Ships Components

Society of Naval Architects and Marine Engineers, Washington, DC

J. G. Early

April 1982

The Effect of Cracks on the Reliability of Multilayer Capacitors

National Materials Advisory Board, Washington, DC

S. W. Freiman

April 1982

Effects of Crack Growth on the Load-Displacement Characteristics of

Precracked Specimens under Bending

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

T. -J. Chuang, E. R. Fuller, Jr. R. J. Fields and L. Chuck

May 2-5, 1982

Stress Enhanced Crack Blunting

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

T.-J. Chuang, E. R. Fuller, Jr. and T. A. Michalske

May 2-5, 1982

Comparison of Static and Dynamic Fatigue in A1 2 0 3

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

S. W. Freiman and A. C. Gonzalez

May 2-5, 1982

Fracture of 95PbZr03 -5PbTi03

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

S. W. Freiman and J. J. Mecholsky

May 2-5, 1982

Effects of Chemical Environments on Crack Growth in Soda-Lime Glass

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

S. W. Freiman and G. S. White

May 2-5, 1982

562-58
Physics of Fracture

Sosman Lecture, 84th Annual Meeting of the American Ceramic Society,

Cincinnati, OH

B. R. Lawn

May 2-5, 1982

A Chemical Approach to Predicting Stress Corrosion Effects in

Brittle Materials

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

T. A. Michalske and S. W. Freiman

May 2-5, 1982

Crack Healing in Silica Glass

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

T. A. Michalske and E. R. Fuller, Jr.

May 2-5, 1982

Analysis of Oxide : Matrix Interfaces in Si 3 N 4

84th Annual Meeting of the American Ceramic Society, Cincinnati, OH

N. J. Tighe

May 2-5, 1982

Elastic-Plastic Fracture Mechanics Research at NBS

Research Institute for Strength and Fracture of Materials, Sendai,

Japan

H. I. McHenry

May 7, 1982

Magnetic Field Effects on Tensile Behavior of Fe-Cr-Ni Alloys at

4 K

International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

R. P. Reed

May 11, 1982

Effect of Cryogenic Temperatures on the Mechanical Performance of

Glass-Fabric Reinforced Epoxy and Polyimide Matrix Laminates

International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

M. B. Kasen

May 12, 1982

Stainless-Steel Elastic Constants at Low Temperatures: A Review

International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

H. M. Ledbetter

May 12, 1982

Mechanical Properties of Austenitic Stainless Steel Castings at 4 K International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

H. I. McHenry

May 12, 1982

562-59
Low Temperature Flow Strength of Austenitic Stainless Steels

International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

R. P. Reed

May 12, 1982

Fracture Properties of 25-Mn Austenitic Steel and Its Welds at 4 K International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

H. I. McHenry

May 13, 1982

Structural Alloys for Cryogenic Service

International Cryogenic Engineering Conference/International Cryogenic

Materials Conference (ICEC/ICMC), Kobe, Japan

H. I. McHenry

May 13, 1982

TEM Study of Indentation of Brittle Materials

Symposium on .Hardness, National Bureau of Standards, Washington, DC

B. J. Hockey

May 17-18, 1982

Elastic-Property Studies at NBS/Boulder

University of Tokyo (Roppongi campus), Materials Science Department,

Tokyo, Japan

H. M. Ledbetter

May 18, 1982

Fracture Mechanics Approach to Fitness-for-Purpose Standards

American Welding Society Conference on Fitness-for-Purpose in

Welded Construction, Atlanta, GA

H. I. McHenry

May 18, 1982

Low-Temperature Elastic-Constant Anomalies in Austenitic Stainless

Steel

s

Plasticity and Workability Section, Fundamental Research Laboratories,

Nippon Steel, Kawasaki, Japan

H. M. Ledbetter

May 20, 1982

Dynamic Hardness Testing

Microhardness-Related Research Symposium, National Bureau of Standards,

Washington, DC

R. S. Polvani

May 25, 1982

Fracture Toughness of Piezoelectric Materials

U.S. -Japan Workshop on Piezoelectric and Dielectric Ceramics,

Tokyo, Japan

S. W. Freiman

May 1982

562-60
Lifetime Predictions for Ceramic Capacitors

U.S. -Japan Workshop on Piezoelectric and Dielectric Ceramics,

Tokyo, Japan

S. W. Freiman and S. M. Wiederhorn

May 1982

Fracture of Ferroelectric Materials

U.S. -Japan Workshop on Piezoelectric and Dielectric Ceramics,

Tokyo, Japan

R. C. Pohanka and S. W. Freiman

May 1982

Creep Cavitation and Fracture due to a Stress Concentration in

7k Cr-lMo Steel

2nd International Symposium on Defects, Fracture and Fatigue,

Quebec, Canada

T. -S. Liu, T. J. Delph, and R. J. Fields

June 1, 1982

In-Process Weld Inspection for New Construction

Interdisciplinary Program for Quantitative Nondestructive Evaluation,

Iowa State Uni vers ity/Navy/DARPA, Ames, I

C. M. Fortunko

June 2, 1982

Environmental Testing Under Conditions that Promote Branch Crack

Forman in Double Beam Specimens

Third International Conference on Hydrogen and Materials, Paris,

France

C. G. Interrante

June 10, 1982

Fracture Mechanics Applications to Failure Analysis and Prevention

in Structures and Components

Centro Informazioni Studi Esperienze, CISE, Milan, Italy

C. G. Interrante

June 14, 1982

Testing Cements in the Cerro Prieto Geothermal Field

API Standardization Conference, Colorado Springs, CO

R. F. Krause, Jr.

June 14, 1982

Hyatt Regency Skywalk Collapse

CBT Failure Analysis Workshop, National Bureau of Standards,

Gaithersburg, MD

T. R. Shives

June 1982

Fracture of Ceramic Capacitors

Seminar at Japanese National Defense Academy, Yokosuka, Japan

S. W. Freiman

June 1982

562-61
Contact Fracture in Brittle Materials

International Symposium on Contact Mechanics and Wear of Rail/Wheel

Systems, University of British Columbia, Vancouver, Canada

S. M. Wiederhorn and B. R. Lawn

July 6-9, 1982

The Residual Strength Diagram Based on the Plastic Yield Strip

15th ASTM National Symposium on Fracture Mechanics, College Park,

MD

R. de Wit

July 7, 1982

Post-Yield Crack Opening Displacement for Surface Cracks in Tensile

Panel

s

15th ASTM National Symposium on Fracture Mechanics, College Park,

MD

D. T. Read

July 7, 1982

Microscopy of Erosion

MICRO '82, International Symposium on the Use of Microscopy in

Studying Materials Degradation, London, England

B. J. Hockey

July 12-16, 1982

Some Recent Developments in Indentation Fracture

MICRO '82, International Symposium on the Use of Microscopy in

Studying Materials Degradation, London, England

B. R. Lawn

July 12-16, 1982

Excitation of Pure Ultrasonic Modes with Electromagnetic- Acoustic

Transducers

AISI, DARPA, NBS Workshop on Process Control for the Steel Industry,

Gaithersburg, MD

C. M. Fortunko

July 28, 1982

Use of Electromagnetic-Acoustic Transducers in Weld Inspection

U.S. Navy, NAVSEA, Materials Branch, Crystal City, VA

C. M. Fortunko

July 28, 1982

Nondestructive Evaluation of Thick Weldments Using Arrays of

Electromagnetic- Acoustic Transducers

DARPA-AF Review of Progress in Quantitative NDE, La Jolla, CA

C. M. Fortunko

August 2, 1982

SRMs for Determination of Retained Austenite in Hardened Steels

31st Annual Conference on X-ray Analysis, Denver, CO

G. E. Hicho

August 5, 1982

562-62
Dislocation Processes at Crack Tips

Gordon Research Conference on Solid State Studies in Ceramics,

Plymouth, NH

R. M. Thomson, E. R. Fuller, Jr., and I.-H. Lin

August 9, 1982

Long-term Fracture Phenomena of Structural Ceramics

Gordon Research Conference on Solid State Studies in Ceramics,

Plymouth, NH

R. J. Fields

August 9-13, 1982

Division Seminars

Statistical Theory of Physical Properties of Random Media

Ekkehart Kroner

Institute for Theoretical and Applied Physics, University of Stuttgart,

Stuttgart, West Germany

October 19, 1981

Fracture Mechanics Analysis of Pipeline Welds

M. G. Dawes

The Welding Institute, London, England

October 20, 1981

Elastic Properties of Textured Metals

H. M. Ledbetter

Division 562, NBS/Boulder

October 27, 1981

Gauge-Invariant Formulation of the Continuum Theory of Defects

G. K. D. Gairola

Institute for Theoretical and Applied Physics, University of Stuttgart,

Stuttgart, West Germany

January 12, 1982

Fracture Mechanics Analysis of Surface Flaws in Pipeline Girth

Welds

R. B. King

Division 562, NBS/Boulder

January 18, 1982

Degradation of Composites by Moisture Absorption

R. D. Kriz

Division 562, NBS/Boulder

February 1, 1982

Studies of Elastic-Plastic Fracture Using Dislocation Theory

I. -H. Lin

Division 562, NBS/Boulder

February 16, 1982

562-63
NDE Research by EPRI

Mel Lap ides

Electric Power Research Institute (EPRI), Palo Alto, CA

February 26, 1982

New Experimental Capabilities in the Fracture and Deformation

Division

J. C. Moulder

Division 562, NBS/Boulder

March 1, 1982

COD of Surface Flaws in Pipeline Girth Welds

Y.-W. Cheng

Division 562, NBS/Boulder

March 15, 1982

Properties of Stainless Steel Castings at 4 K

T. A. Whipple

Division 562, NBS/Boulder

March 29, 1982

Magnetoelastic Properties of Austenitic Stainless Steels at Low

Temperatures

H. M. Ledbetter

Division 562, NBS/Boulder

April 12, 1982

Microdeformation Behavior of Beryllium

R. S. Polvani, C. S. Tilghman, and B. W. Christ

Division 562/NBS Boulder

April 21, 1982

Fundamentals of Grain Boundary Segregation

M. B. Kasen

Division 562, NBS/Boulder

April 26, 1982

Ultrasonic Wave Propagation in Random and Periodic Particulate

Composites

Vikram K. Kinra

University of Colorado, Department of Mechanical Engineering,

Boulder, CO

May 5, 1982

Use of Small Scale Indentation Flaws to Study Fatigue Properties of

Glass

T. P. Dabbs

School of Physics, University of New South Wales, Kensington,

Austral ia

May 7, 1982

562-64
Flaw Detection and Weldments by EMATs and Possible Signal Processing

Techniques

R. E. Schramm

Division 562, NBS/Boulder

May 10, 1982

Design of Electrical Coupling Networks for Acoustic Transducers

with Compact Responses

Dov Hazony

Case-Western Reserve University, Cleveland, OH

May 13, 1982

Using EMATs for Stress Measurement and Weld Inspection

G. A. Alers

Magnasonics, Inc., Albuquerque, NM

May 20, 1982

Analytical Methods in Eddy Current NDE

Professor B. A. Auld

Stanford University, Stanford, CA

May 31, 1982

Small -Angle Neutron Scattering Study of Grain Boundary Cavitation

M. H. Yoo

Metals and Ceramics Division, Oak Ridge National Laboratory, Oak

Ridge, TN

June 14, 1982

Direct Observations of Crack-Tip Dislocations in Metals

S. M. Ohr

Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN

June 15, 1982

Testing Cements in the Cerro Prieto Geothermal Field

R. F. Krause, Jr.

Division 562, NBS/Boulder

June 16, 1982

Chemical Effects on Ceramic Fracture

T. A. Michalske

Sandia National Laboratories, Albuquerque, NM

June 25, 1982

Standard Reference Materials for Determination of Retained Austenite

in Hardened Steels

G. E. Hicho

Division 562, NBS/Boulder

August 4, 1982

562-65
Technical and Professional Committee Participation and Leadership

American Ceramic Society

E. R. Fuller, Jr., Chairman Elect of the Baltimore-Washington

Chapter

R. F. Krause, Jr., C. L. McDaniel, N. J. Tighe, and

S. M. Wiederhorn, Members

Executive Committee

N. J. Tighe, Member

Forum Committee

N. J. Tighe, Member

Sosman Lecture Committee

N. J. Tighe, Member

Editorial Committee

S. M. Wiederhorn, Subchairman

American Institute of Mining, Metallurgical, and Petroleum Engineers

Metallurgical Society

Composites Committee

M. B. Kasen, Member

Metals information Publications Committee

J. H. Smith, Member

American Iron and Steel Institute

Task Force on Evaluation of Fracture Criteria for Ship Steels and

Weldments

H. I. McHenry, Member

American Petroleum Institute

Task Group on Cements for Geothermal Wells

E. R. Fuller, Jr. and R. F. Krause, Jr., Members

American Society for Metals

Definitions of Metallurgical Terms

C. G. Interrante, Member

American Society for Testing and Materials

Committee on Terminology (COT) of Committee on Standards

C. G. Interrante, Member and Chairman of Task Group on Liaison Members

Committee C-21 Ceramic Whitewares

S. M. Wiederhorn, Member

Committee D30 Composite Materials

M. B. Kasen, Member

Subcommittee D30-05 High-Modulus Fibers and Their Composites

M. B. Kasen, Member

Committee E4 Metallography

R. J. Fields, Member

Committee E9 Fatigue

R. J. Fields, Member

Subcommittee E9.01 Fatigue Research

R. C. Dobbyn, Member

Subcommittee E9.03 Fatigue of Composites

M. B. Kasen, Member

562-66
Subcommittee E10-02-A Computer Methods for Analysis of Charpy

Data

C. G. Interrante, Member

Committee E24 Fracture Testing

B. W. Christ (Member of Executive Committee), R. de Wit,

R. J. Fields, E. R. Fuller, Jr., G. E. Hicho, C. G. Interrante (Member of Executive Committee), D. T. Read,

J. H. Smith, R. L. Tobler, and S. M. Wiederhorn, Members

Task Group E24.01.09 Elastic Fracture

R. L. Tobler, Member

Subcommittee E24.02 Fractography

G. E. Hicho, Vice Chairman

Subcommittee E24.03 Alternative Test Methods

B. W. Christ, Chairman

Task Group E24.03.03 Precracked Charpy Testing Methods

C. G. Interrante, Member

Subcommittee E24.05 on Terminology

C. G. Interrante, Chairman and R. de Wit, Secretary

Task Group E24.06 Fracture Mechanics Applications

D. T. Read, Member

Task Group E24.06.02 Application of Fracture Analysis Methods

(Cooperative Task Group under E24.06 and E24.08)

R. de Wit and D. T. Read, Members

Subcommittee E24.07 on Fracture of Non-Metals

S. W. Freiman, Chairman and E. R. Fuller, Jr., Member

Task Group E24.07.01 Fracture Toughness Testing of Concretes

and Rocks

E. R. Fuller, Jr., Member

Task Group E24.07.02 Double-Torsion Technique

E. R. Fuller, Jr., Member

Task Group E24.08 Elastic-Plastic and Fully Plastic Fracture

Mechanics Technology

D. T. Read, Member

Task Group E28.04.03 Verification of Alignment Under Tensile

Load

B. W. Christ, Chairman

Committee E38 Resource Recovery

J. G. Early, Secretary and Member of Executive Committee

Subcommittee E38.02 Ferrous Metals Resource Recovery

J. G. Early, Vice Chairman

Joint ASTM-ASME-MPC Committee on Effect of Temperature on the

Properties of Metals

R. P. Reed, Member and B. W. Christ, Guest Member representing

NBS

American Society of Mechanical Engineers

Ceramics Committee

N. J. Tighe, Member

Gas Turbine Division

N. J. Tighe, Member

Joint Applied Mechanics Division and Materials Division Committee

on Constitutive Equations

R. de Wit, Member

562-67
Subcommittee 109, Materials -and Fabrication, Pressure Vessel

and Piping Division

R. C. Dobbyn, Chairman

Subcommittee on Fatigue: PV and P. Div.

J. H. Smith, Chairman

Materials and Stresses Committee of the Pressure Piping Code,

B31

H. I. McHenry, Member

American Welding Society

Conference Program Advisory Board, Fi tness-for-Purpose in

Welded Construction

C. M. Fortunko, Member

Compressed Gas Association

Cylinder Specification Subcommittee

B. W. Christ, Member

Department of Energy

Office of Fusion Energy, Materials and Radiation Effects

Branch, Analysis and Evaluation Task Group

N. J. Simon, Member

Subcommittee on Erosion/Corrosion of Turbine Materials

B. J. Hockey, Member

Department of Transportation

Technical Pipeline Safety Standards Committee

B. W. Christ and J. H. Smith, appointment by Secretary of

Transportation

Interagency Coordination Group for the Application of Ceramics to

Heat Engines

S. M. Wiederhorn and N. J. Tighe, Members

International Commission on Glass

Subcommittee VI A

S. M. Wiederhorn, Chairman

International Cryogenic Materials Conference

Governing Board

R. P. Reed, Member

International Institute of Welding

Commission XV - Fundamentals of Design and Fabrication for

Welding

J. H. Smith, Member

Sub-Commission X-E - Significance of Weld Defects with Respect

to Brittle Fracture Failure

H. I. McHenry, Corresponding Member

International Powder Metallurgy Society (Planseeberichte fur

Pul vermetal 1 urgie , Austria)

J. G. Early, Member

562-68
International Society for Stereo! ogy

R. de Wit, Member

International Standards Organization

ISO/TC 164 on Mechanical Testing

C. G. Interrante, Member

ISO/TC 164/SC4 on Toughness Testing

C. G. Interrante, Member

ISO/TC 164/WG1 on Terms, Symbols, Definitions

C. G. Interrante, Member

Mechanical Failures Prevention Group

T. R. Shives and W. A. Willard, Editors

Committee on Mechanisms of Failure

J. G. Early, Chairman

Metals Properties Council

Subcommittee 9 on Materials for the Gasification and Liquefaction

of Coal

J. H. Smith and R. C. Dobbyn, Members

Technical Advisory Committee

R. P. Reed, Member

National Academy of Sciences

Project Advisory Committee on Investigation of Steels for

Improved Weldability in Ship Construction

H. I. McHenry, Chairman

National Institute of Ceramic Engineers

R. J. Fields, Associate Member

National Materials Advisory Board

Committee on Reliability of Ceramics for Heat Engine Applications

S. M. Wiederhorn, Member

National Research Council

Committee on Recommendations for U.S. Army Basic Scientific

Research

S. M. Wiederhorn, Member

Office of Energy-Related Inventions

J. G. Early, Reviewer of Invention Disclosures

Science and Technology, Office of the Assistant Secretary

Ad Hoc Committee for Technical Evaluation of a Proposal to

Revive the Steel making Industry in Youngstown, Ohio

J. G. Early and J. H. Smith, Members

U.S. Civil Service Examiners for Metallurgist

Interagency Board

J. G. Early, Chairman

562-69
Washington Academy of Sciences Board of Managers

E. R. Fuller, Jr., Representative for the Bal timore-Washington

Chapter of the American Ceramic Society and C. G. Interrante,

Representative for the Washington Chapter of the American

Society for Metals

Welding Research Council

Long-Range Planning Committee

H. I. McHenry, Member

Pressure Vessel Research Committee

C. G. Interrante and J. H. Smith, Members

PVRC Hydrogen Embrittlement Subcommittee

C. G. Interrante, Member

Subcommittee on Line Pipe Steels

M. B. Kasen, Member

Task Group on Field Welding

M. B. Kasen, Member

Publ i cations

Anstis, G. R. ; Chantikul, P. ; Marshall, D. B. ; Lawn, B. R. A critical

evaluation of indentation techniques for measuring fracture toughness

I. direct crack measurements. J. Am. Ceram. Soc. 64: 534; 1981.

Arsenault, R. J. ; de Wit, R. Comments on non-spherical and spherical

defects and screw dislocation interaction. Scr. Metal 1. 15: 615;

1981.

Case, E. D. Fracture energy of monoclinic Gd2 0 3

. J. Mater. Sci. 16:

3215; 1981.

Case, E. D. ; Smyth, J. R. ; Hunter, 0. Microcracking in Large-Grained

A1 2 0 3

. Mater. Sci. Eng. 51: 175; 1981.

Case, E. D. ; Smyth, J. R. ; Hunter, 0. Microcracking behavior of

monoclinic Gd2 03

. J. Nucl. Mater. 102: 135; (1981).

Chantikul, P. ; Anstis, G. R. ; Lawn, B. R. ; Marshall, D. B. A critical

evaluation of indentation techniques for measuring fracture toughness

II. strength method. J. Am. Ceram. Soc. 64: 539; 1981.

Chantikul, P. ; Lawn, B. R. ; Marshall, D. B. Micromechanics of flaw

growth in static fatigue: influence of residual contact stresses.

J. Am. Ceram. Soc. 64: 322; 1981.

Cook, R. F. ; Lawn, B. R. ; Dabbs, T. P. ; Chantikul, P. Effect of

machining damage on the strength of a glass ceramic. Commun. J. Am.

Ceram. Soc. 64: 122; 1981.

Datta, S. K. ; Fortunko, C. M. ; King, R. B. Sizing of surface cracks

in a plate using SH waves. McAroy, B. R. , ed. 1981 Ultrasonic

symposium proceeding; 1981. New York: IEEE Publ. #81CH1689~9; 1981.

p. 863

562-70
Datta, S. K. ; Ledbetter, H. M. ; Kinra, V. K. Wave propagation and

elastic constants in particulate composites, chapter in Composite

materials; mechanics, mechanical properties and fabrication. Tokyo,

Japan: Japan Soc. Compos. Mater. ; 1981. p. 30.

de Wit, R. A view of the relation between the continuum theory of

lattice defects and non-eucl idean geometry in the linear approximation.

J. Eng. Sci. 19: 1475; 1981.

de Wit, R. The displacement field of a dislocation distribution,

chapter in Dislocation modelling of physical systems. Ashby, M. F.

Bullough, R. ; Hartley, C. S. ; Hirth, J. P. , eds. Oxford, Engl.:

Pergamon Press; 1981. p. 304.

de Wit, R. ; Interrante, C. G. Application of an elastic-plastic

model to the use of small specimen strength ratio for measuring

fracture toughness. Wullaert, R. A. , ed. Proceedings of the Xth

CSNI specialists meeting on instrumented precracked charpy testing;

1981; Palo Alto, CA. Electr. Power Res. Inst. Publ. ; 1981. p. 5-29.

Elsley, R. K. ; Fortunko, C. M. Improvements in flaw detection in

austenitic stainless steel weldments. McAroy, B. R. , ed. 1981

Ultrasonic symposium proceedings; 1981. New York: IEEE Publ.

#81CH1689-9; 1981. p. 892.

Fields, R. J. ; Chuang, T.-J.; Fuller, Jr., E. R. Effect of deformation

on the fracture of Si 3 N 4 and sialon. Proceedings of the 2nd NATO ASI

on nitrogen ceramics; 1981; Falmer, England. 1981.

Fong, J. T. ; Smith, J. H. Safety factors in fatigue design: arbitrary

and rational, chapter in Critical materials and fabrication issues for

pressure vessels. Fong, J. T. ; Dobbyn, R. C. ; Mordfin, L. , eds. New

York, NY: ASME; Publ. #PVP-PB-047; 1981 March.

Freiman, S. W. ; Fuller, Jr., E. R. Fracture mechanics techniques

for ceramics, rocks, and concrete. Am. Soc. Test. Matls. Spec.

Tech. Publ. 745. Philadelphia, PA: ASTM ; 1981.

Fortunko, C. M. Ultrasonic evaluation of austenitic stainless steel

welds using shear horizontal waves. Appl. Phys. Lett. 39(9): 699;

1981.

Hench, L. L. ; Freiman, S. W. Investigation of the oxidation of hot

pressed Si 3 N 4 with infrared reflection spectroscopy. J. Mater. Sci.

16: 2767; 1981.

King, R. B. ; Herrmann, G. Use of stress measurements with ultrasonics

to nondestructi vely evaluate the J-integral. Eng. Fract. Mech. , 15:

77; 1981.

Kobayashi , K. ; Umebayashi , S. ; Kishi, S. ; Tighe, N. J. ; Fields, R. J. Fracture strength and weibull distribution of p-sialon. J. Ceram. Soc. Jpn. 89(10): 132; 1981.

562-71
Lawn, B. R. ; Howes, V. R. Elastic recovery of hardness indentations.

J. Mater. Sci. 16: 2475; 1981.

Lawn, B. R. ; Marshall, D. B. ; Anstis, G. R. ; Dabbs, T. P. Fatigue

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fusion energy applications at low temperatures--V. Nat. Bur. Stand.

(U.S.) NBSIR 82-1667; 1982.

Reed, R. P. ; Tobler, R. L. Deformation of metastable austenitic

steels at low temperatures, chapter in Materials studies for magnetic

fusion energy applications at low temperatures--V. Nat. Bur. Stand.

(U.S.) NBSIR 82-1667; 1982. p. 15.

Reed, R. P. ; Tobler, R. L. ; Elmer, J. W. Temperature dependence of

flow strength of Fe-20Cr-16Ni-6Mn-0. 2N and Fe-18Cr-10Ni-l. 5Mn-0. IN

(304LN) austenitic steels, chapter in Materials studies for magnetic

fusion energy applications at low temperatures--V. Nat. Bur. Stand.

(U.S.) NBSIR 82-1667; 1982. p. 29.

Shives, T. R. Testing of components from gas pipeline. NTSB Accident

No. DCA-F-P006; Letter Report. 1982.

Simon, N. J. NBS-DOE workshop: materials at low temperatures,

chapter in Materials studies for magnetic fusion energy applications

at low temperatures--V. Nat. Bur. Stand. (U.S.) NBSIR 82-1667;

1982. p. 481.

562-82
Tobler, R. L. ; Reed, R. P. Ductile fracture with serrations in

AISI 310S stainless steel at liquid helium temperature, chapter in

Materials studies for magnetic fusion energy applications at low

temperatures —V. Nat. Bur. Stand. (U.S.) NBSIR 82-1667; 1982. p. 145.

Tobler, R. L. ; Reed, R. P. Tensile and fracture properties of

manganese-modified AISI 304 type stainless steel, chapter in Materials

studies for magnetic fusion energy applications at low temperatures--V.

Nat. Bur. Stand. (U.S.) NBSIR 82-1667; 1982. p. 59.

Whipple, T. A. The effect of delta-ferrite on the mechanical properties

of CF8M stainless steel castings at 4 K, chapter in Materials

studies for magnetic fusion energy applications at low temperatures —V. Nat. Bur. Stand. (U.S.) NBSIR 82-1667; 1982. p.. 289.

Whipple, T. A.; Brown, E. L. Deformation and fracture behavior of

duplex austenite/delta- ferrite materials at 4 K, chapter in Materials

studies for magnetic fusion energy applications at low temperatures —V. Nat. Bur. Stand. (U.S.) NBSIR 82-1667; 1982. p. 269.

Whipple, T. A.; McHenry, H. I. Weldments and castings for liquid

helium service, chapter in Materials studies for magnetic fusion

energy applications at low temperatures —V. Nat. Bur. Stand. (U.S.)

NBSIR 82-1667; 1982. p. 233.

Read, D. T. Experimental measurements of applied J-integral in

HY 130 tensile panels and implications for fitness-for-service

assessment. Nat. Bur. Stand. (U.S.) NBSIR 82-1670; 1982.

Marshall, R. D. ; Pfrang, E. 0.; Leyendecker, E. U. ; Woodward, K. A.; Reed, R. P. ; Kasen, M. B. ; Shives, T. R. Investigation of the

Kansas City Hyatt Regency walkways collapse. Nat. Bur. Stand.

(U.S.) NBSIR 82-2465; 1982. 353 p.

Early, J. G. ; Ballard, L. D. Equivalency of foreign and domestic

material specifications for ships components. Nat. Bur. Stand.

(U.S.) NBSIR 82-2481; 1982. 262 p.

Chuang, T

. - J . ; Fuller, Jr., E. R. ; Fields, R. J. ; Chuck, L. Effects

of crack growth on the load-displacement characteristics of precracked

specimens under bending, Nat. Bur. Stand. (U.S.) NBSIR 82-2504;

1982.

39 p.

Wiederhorn, S. M. ; Freiman, S. W. ; Fuller, Jr., E. R. ; Simmons, C. J. Effects of water and other dielectrics on crack growth. Nat.

Bur. Stand. (U.S.) NBSIR 82-2524; 1982. 60 p.

Christ, B. W. ; Polvani, R. S. ; Hocken, R. J. ; Borchardt, B.

Charlton, T. Micromechanical properties of beryllium and other

instrument materials, Nat. Bur. Stand. (U.S.) NBSIR 82-2542; 1982.

41 p.

562-83
Christ, B. W. Review of May 1982 Report by Battel le/Col umbus on the

economic effects of fracture in the United States. Nat. Bur.

Stand. (U.S.) STP, in press.

Sponsored- Conferences

NBS-DOE Workshop on Materials at Low Temperatures

Kiandra/Tal isman Lodge, Vail, CO

October 1981

ONR-NBS Workshop on Contact Damage in Ceramic Materials at Elevated

Temperatures

National Bureau of Standards, Gaithersburg, MD

January 21-22, 1982

Mechanical Failures Prevention Group Symposium on Time-Dependent

Failure Mechanisms and Assessment Methodologies

National Bureau of Standards, Gaithersburg, MD

April 20-22, 1982

Seventh International Symposium on Ultrasonic Imaging and Tissue

Characterization

National Bureau of Standards, Gaithersburg, MD

June 6-9, 1982

Consulting and Advisory Services

DARPA, AISI, and NBS advisory workshop on sensors for steel industry

C. M. Fortunko

Electric Power Research Institute

C. M. Fortunko

Lawrence Livermore National Laboratory

C. M. Fortunko

Rockwell International Science Center

C. M. Fortunko

U. S. Army, ARRADCOM

C. M. Fortunko

U. S. Navy, DTNSRDC

C. M. Fortunko

NBS Research Advisory Committee to Dr. E. Ambler

E. R. Fuller, Jr.

Gas Research Institute, International Steering Committee on Cryogenic

9 Percent Nickel Steel

H. I. McHenry

562-84
Consultation on material properties at low temperatures for large

superconducting magnet structures being built in the U.S., (General

Dynamics, General Electric, Westinghouse, Lawrence Livermore Labs.,

Oak Ridge National Lab.), Japan, Germany, and Switzerland

R. P. Reed

Department of Energy, Office of Fusion Energy, Research Advisory

Committee

R. P. Reed

Metal Properties Council, Technical Advisory Panel

R. P. Reed

National Science Foundation, Materials Research Advisory Committee,

Metals, Ceramics, Polymers, and Metallurgy Oversight Committee

R. P. Reed

External Recognition

Degradation of Materials III: Toughening and Fracture Toughness

Fall Meeting of the Metallurgical Society and the Basic Science

Division of the American Ceramic Society, Louisville, KY, Co-chairman

October 12-15, 1981

E. R. Fuller, Jr.

Doctoral Advisory Committee of Murari Singh, New York State College

of Ceramics at Alfred University, Honorary Member

June 1982

E. R. Fuller, Jr.

Sosman Lecture Award

American Ceramic Society

B. R. Lawn

1982

Fitness-for-Purpose Validation in Welded Constructions Conference,

Vice-Chairman

May 1982

H. I. McHenry

International Cryogenic Materials Conference, Kobe, Japan, Session

Chairman

May 1982

R. P. Reed, H. I. McHenry, and M. B. Kasen

TECHNION, Israel Institute of Technology

Invited Professor

September-October 1981

S. M. Wiederhorn

562-85
Industrial Interactions

Joint development program of low temperature structural austenitic

steel, Armco Steel, Middleton, OH, R. P. Reed

Joint characterization of low temperature properties of structural

alloys, Kawasaki Steel, Nippon Steel, Kobe Steel, Nippon-Kokan

Steel, Japanese Steel Works, DOE (Office of Fusion Energy), and

NBS, R. P. Reed

and H. I. McHenry

Development of low temperature codes and standards, joint research

effort, includes development of test methodology, round-robin

testing, and development of materials specifications, Metal Properties

Council (ASTM, ASME, ASM, AWS), DOE (Office of Fusion Energy), NBS,

and about 20 companies, R. P. Reed

Development of fitness-for-purpose criteria for proposed Alaska

Natural Gas Pipeline, joint research and collaboration, NBS, Welding

Research Council, Northwest Pipeline Company, Exxon, Nova, and

Canadian Welding Research Council, R. P. Reed, M. B. Kasen, C. M. Fortunko, and H. I. McHenry

Possible use of electromagnetic-acoustic transducers in nondestructive

evaluation, Panametrics, Inc., Waltham, MA, C. M. Fortunko

Measurement of residual stresses and inspection of residual stresses

and inspection of weldments using electromagnetic-acoustic transducers,

Magnasonics, Inc., Albuquerque, NM, C. M. Fortunko

Nondestructive evaluation of stainless steel weldments, Battel le/

Northwest Laboratories, Richland, WA and Argonne National Laboratory,

Chicago, IL, C. M. Fortunko

Thickness gaging of tubular goods, Republic Steel, Cleveland, OH,

C. M. Fortunko

In-service monitoring in nuclear industry, AMDATA, Inc., San Jose,

CA, C. M. Fortunko

Design of circuits for nondestructive evaluation, Rockwell International Science Center, Thousand Oaks, CA, C. M. Fortunko

Participation in round- robin fracture mechanics prediction of heavy

section structural testing pressure vessel test, Oak Ridge National

Laboratories, Oak Ridge, TN, D. T. Read

Refinement of the manufacturing specifications for the G-10CR

cryogenic grade of insulating nonmetal lie laminate with the Spaulding

Fiber Co., Tonawanda, NY, Westinghouse Industrial Laminates Corp.

,

Hampton, SC, Synthane-Taylor Corp., Oaks, PA, NVF Corp., Kenneth

Square, PA, and the Norplex Corp., LaCrosse, WI , M. B. Kasen

562-86
POLYMER SCIENCE AND STANDARDS DIVISION (563)

Ronald K. Eby, Chief

Martin G. Broadhurst, Deputy Chief

B. A. Hyde, Secretary

Although synthetic polymers have been used as materials for technology

during only three quarters of a century, they have left little of our economy, technology, industry, science, and culture untouched. We have

moved rapidly into an age in which an evergrowing number of humanity's

needs are served by polymers. The volume currently produced exceeds

that of steel and forms the basis of industries which add over $90 billion

of value by manufacturer (a measure of the relative economic importance

of manufacturing among industries) and provide 3.4 million jobs. Recent

summaries show that polymers and polymer composites research already

accounts for about 47 percent of the total industrial R&D expenditure

for metals, polymers, and inorganic materials. Among these materials,

polymers also constitute about 39 percent of the value added by manufacturer, 49 percent of the jobs, 45 percent of the number of scientific

publications, and 39 percent of the American Society for Testing and

Materials (ASTM) standards.

Polymers have been shaped by intellectually sophisticated research which

has been recognized by a number of Nobel Prizes. The resulting materials

have contributed to national industrial productivity through their

economy, ease of fabrication, and useful properties such as low density,

corrosion resistance, and toughness. Polymers are energy efficient; the

largest volume polymer, polyethylene, uses 29 percent of the energy per

unit volume required by steel for conversion from raw to refined material

and yields further savings in processing and shipping. In fact, studies

have shown that for every barrel of oil used to make plastic products,

approximately one barrel is saved in comparison with the use of the next

best alternative material. These useful properties have enabled polymers

to contribute to increased national economic strength both by creating

entirely new products and by substituting for other materials in existing

products.

Polymers have entered a widening range of increasingly sophisticated and

demanding applications. Polyvinylidene fluoride films are used as piezoelectric transducers in high fidelity sound systems. Structural

parts of aircraft are constructed from composites with a polymer matrix

and sometimes a polymer reinforcement. Polyurethane elastomers are used

to pump blood in circulatory assist devices. The list of such examples

is very long, and includes trends for the increased use of polymers in

packaging, construction, transportation, national security, electronics,

information handling, clothing, electrical appliances, energy, dentistry

and medicine. Since polymer science and technology is on the steep part

of the learning curve, these trends create many new needs for scientific

concepts, measurements, standards, and data that can be used to ensure their reliable performance in the use, processing, and other phases of

the material cycle. The programs of the Division are aimed at the

fundamental scientific basis of these needs.

563-3
To identify the key needs with the best prospects for payoff, the managers

of the Polymer Science and Standards Division make structured visits to

industrial and Government laboratories. Visited sites include Bell

Laboratories, E. I. DuPont de Nemours, Inc., Johnson and Johnson, Army

R&D Command, General Motors Corporation, Boeing, and Lawrence Livermore

Laboratories. Surveys have been conducted in the areas of durability,

composites, and processing. These and other contacts with research

associates, experts in industry, trade associations, standards associations, guest workers, Government, and academia ensure that the Division's

efforts are directed toward fostering the effective use of polymers in

solving generic national problems. These include the growth of the

economy, national security, efficient Government, materials utilization,

and conservation of critical materials.

Current activities are associated into areas concerned with long-term

research on the scientific basis for mechanical reliability in load-bearing

applications, chemical durability, lifetime prediction, migration of

protective additives, characterization methods, standards for molecular

composition and performance properties, dielectric properties, processing

and reliability of composites, and reliable dental and medical materials.

Substantial cooperative efforts are conducted with research associates

from a number of industries, universities, the Department of Defense,

the National Institutes of Health, the American Dental Association

(ADA), the Food and Drug Administration, and the Bureau of Engraving and

Printing. All these efforts lead the staff of the Division into an examination of the scientific basis of those properties which are of concern to people who use, design, and produce useful polymer objects.

This work helps society capture, in safe and satisfying ways, the benefits

of the increasingly widespread application of polymers.

FY82 SIGNIFICANT ACCOMPLISHMENTS

POLYMER STANDARDS FOR PROCESS CONTROL AND EQUITY

Task 12132

• Construction of a sel fcal ibrating gel permeation chromatograph

(GPC) has been completed. A light scattering detector for the

GPC measures, in real time, the scattering intensity of the

effluent as a function of scattering angle. This allows immediate identification of difficulties such as molecular association, microgel formation, etc. which affect the validity of the

molecular weight determinations. This instrument will be utilized for the more rapid characterization of new polymer molecular

weight standards.

• A high performance liquid size exclusion chromatograph laboratory has been established for the determination of the molecular

weight and molecular weight distribution of polymer samples. The

apparatus has been automated and may be operated at temperatures

up to 150 °C, the temperature required for the dissolution of

polyethylene and certain other crystalline polymers. Graphics

and database capabilities are built into the software to allow

the user easy interpretation of the data once it is collected.

563-4
• The certification of Standard Reference Material 1470 for

transmission of helium, carbon dioxide, oxygen, and nitrogen

gases has been completed. Gas transport properties of polymeric

materials are the major determinant of suitability for end use

in a great variety of applications ranging from food and

beverage packaging, industrial gas separation processes, and

' sterilization of medical devices, to substrates and packages

for semiconductor products. Gas molecules are useful as probes of materials properties at the microstructural level.

• Polymer properties can be greatly altered by controlling the

size and shape of the phase separated domains of polymer

blends and copolymers. In collaboration with Dr. H. Hasegawa

of Kyoto University, we have prepared model systems of polystyrenepolyisoprene which have regular lamellar domains. Dimensions

of the deuterium labeled polystyrene block of this di block

copolymer and the dispersed homopolystyrene molecules have

been measured at different directions relative to the domain

orientations by small angle neutron scattering (SANS). Work

on the characterization of blends by SANS is being carried out

in collaboration with a Research Associate from Exxon.

• A new statistical mechanical model for a chain liquid has been

developed which shows a sol id-1 iquid transition as well as a liquid-vapor transition. This work is being carried out in

collaboration with R. H. Lacombe of IBM (Fishkill). This model

may prove to be useful in describing the phase behavior of

polar polymer blends.

• A new instrument for forced Rayleigh light scattering is being

completed. A split laser beam is recombined at a small crossing

angle on a sample which includes a trace of polymer labeled with

a photochromic dye. This beam is pulsed to produce an interference pattern which bleaches a holographic grating in the sample.

A second laser beam is diffracted by the grating. As the labeled

polymers diffuse, the grating is destroyed. Thus, measuring the

intensity decay of the diffracted beam yields the diffusion

coefficient of the labeled species. Since the distance scale is

typically several orders of magnitude smaller than macroscopic

tracer methods, it is possible to measure extremely small diffusion coefficients such as those expected for polymer molecules

in concentrated solutions and melts.

TESTS, STANDARDS, AND CHARACTERIZATION FOR MANUFACTURING AND

DURABILITY OF DENTAL AND MEDICAL MATERIALS

Task 12135

• A silver staining technique developed for investigating wear

damage in dental composites was applied to assessment of microleakage and composite restorations and increased precision relative to a more laborious radioisotope (Ca45

) technique was demonstrated.

563-5
• A promising new monomer type, polythiols, was introduced to the

dental materials research community. A high molecular weight,

moderately viscous polythiol, pentaerythritol tetra (3-mercaptopropionate), has promise for reducing residual unsaturation and

polymerization shrinkage in dental composites.

• Developed a procedure employing coupling agents and a mineralization step that achieves a degree of stable bonding to dentin

approximately three times that hitherto reported. As a result,

the potential exists for improved clinical treatment of erosion,

root caries and other conditions by reducing the amount of dentin

that needs to be cut for mechanical retention.

• Several new dental cement innovations were introduced to the

dental materials research community. Arousing particular dental

profession and industry interest is a cement formulation based

on hexyl vanillate, ethoxybenzoic acid and zinc oxide. Low water

sorption, high strength, non-inhibiting to free radical polymerization of subsequently applied composites or resins and predictably good tissue tolerance are important characteristics of this

new cement.

• Silver staining and small angle x-ray scattering analysis of

removed clinical composite restorations have been used to define

mechanisms of wear. In the laboratory a softening of the composite resin matrix by a range of food-simulating solvent media

has been shown to produce similarly damaged materials. This

information has permitted appropriate modification of i_n vitro

testing and resulted in emphasizing the crucial importance of

the degree of cure in the composite polymer.

• Fourier Transform Infrared has been used to demonstrate the

extent of under cure of dental composite resin matrices achieved

at oral temperatures relative to that reached at higher temperatures. A higher degree of cure is obtained by building more polymer backbone flexibility into the monomer formulation indicating a viscosity controlled process. These results provide

important guides for laboratory testing and developmental directions of the dental industry.

• Research pin-pointed food debris and oral liquid interactive

softening of dental composite restorations as initial steps in

clinical loss of restoration material. Based on these results,

an erosion (high velocity liquid jet) test was designed and

assembled. SEM examination of composite surfaces exposed to the

test revealed surface deterioration similar to that experienced

clinically. The test in conjunction with other wear test procedures is expected to provide industry and other research groups

with an important assist in development of more durable composite

restorations.

• A new concept for evaluation of porcelain-metal bond strengths

has been developed. The test uses four-point bending of a metal

strip to which porcelain is fused and measures a tensile strength

563-6
without influence from shear stresses. Three dental manufacturers

have sent personnel to develop a first hand experience with the

test procedure which is anticipated to be useful in industrial

examinations of porcelain-alloy combinations and as a specification test method.

• Amines have been shown in this laboratory to be more reactive

with the resin, BIS-GMA, than current commercial materials.

They have now also been shown to be useful for upgrading surgical

bone cement. These amines in conjunction with a substitution

of dicyclopentyloxyethyl methacrylate for the presently used

methyl methacrylate give a faster cure with less liberation of

heat.

• Characterization of the porosity in low modulus porous polymeric

materials designed for medical and dental implant purposes is

important for establishing a correlation of porosity and the

implant stabilizing tissue or bone ingrowth. Mercury intrusion,

BET surface area and quantitative stereology measurements have

been made. The nature of the porosity characteristics as determined by each technique is being defined.

MECHANICAL DURABILITY OF POLYMERS

Task 12136

• Carbonyl concentrations have been determined by FTIR for fatigued

ultra high molecular weight polyethylene as a function of number

of cycles, frequency and peak stress level. The results suggest

that mechanical failure occurs at a particular concentration of

carbonyls. The measurement of carbonyl concentration may form

the basis of an NDE method.

• Carbon -13 NMR techniques have been developed to elucidate molecular structure of ultra high modulus polymeric materials. The

fraction of material in the form of molecules that bridge one crystalline lamella to another has been determined. Bridge

molecules are thought to be responsible for the high tensile

properties and the quantitative NMR determinations can be used

to evaluate the effects of processing conditions on the molecular

arrangements. This technique is being applied to high strength

poly (ethylene terephthalate) fibers in a joint project with the

Firestone Tire & Rubber Co.

• A new improved test method for environmental stress crack resistance of ethylene-based plastics has been developed. The method

has the advantages of a reduction in the time required to carry

out the test, and a reduction of experimental scatter in the

data. A description of the test method and a summary of test

results, including the appropriate statistical data, has been

presented to Committee D-20.12.03 of the ASTM.

• A viscoelastic relationship has been developed that is capable

of describing quantitatively both creep and recovery behavior

563-7
of polymeric materials which have not been mechanically preconditioned. Previous theories could be applied successfully only

to materials that were first mechanically conditioned and thus

the mechanical behavior of as-processed materials could not be

adequately predicted.

• The creep and stress relaxation behavior of ultra high molecular

weight polyethyl enes used in synthetic implant applications has

been determined as a function of molecular weight and various

thermal treatments. Electron microscopic investigations of

deformed specimens have shown that preferential deformation

occurs at boundaries which delineate the interfaces between the

sintered grains of raw polymer.

• A torsional dilatometer has been designed and constructed to

determine the effects of torsion on the volume of polymer glasses.

The data will serve to test theories concerning the behavior of

polymer glasses under deformation and the effects of deformation

on the aging of these materials.

PROCESSING AND RELIABILITY OF POLYMER COMPOSITES

Task 12137

• A failure model has been developed and applied to elastomer modified epoxy formulations. The temperature dependence of the

fracture energy could be described with a single Arrhenius type

activation energy whose value was identical to that obtained

from yield experiments. This provides the first direct evidence

that yielding is a crucial step in the toughening mechanism of

elastomer modified epoxy resins systems used in aerospace

appl i cations.

• A joint program involving NASA, Hercules, Hexcel , the University

of Illinois, and NBS is addressing the need for test procedures

to assess the susceptibility of polymer composites to delamination. Delamination is a major concern in the mechanical reliability of continuous-fiber reinforced composites. Results

during the past year have led to guidelines for the design of

test specimens in terms of size, geometry, and lay-up (the

sequence of fiber layers and their orientation).

• A research associate from Martin Marietta Corporation, spent

six months at NBS applying Fourier transform infrared spectroscopy (FTIR) to characterization of the processing of composites

used in the Space Shuttle Program. Results indicated that IR

spectroscopic data could be used to improve the processibi 1 ity

of composites.

• A model has been developed to analyze small angle x-ray data of

particulate composites in terms of three phases: the polymer

matrix, the particulate reinforcement, and microcracks or voids.

From this model the content and characteristic lengths of microcracks or voids can be determined from the angular dependence

563-8
of the x-ray scattering intensities. The method provides a means of assessing the state of damage of particulate-reinforced

composites.

• An ultrasonic test method has been developed to study the curing

process (the liquid to solid conversion) in thin layer films.

The method will provide a better understanding of the chemistry

of processing thermoset polymers and more reliable mechanical

properties data of polymer matrix materials.

• A spectroscopic technique has been developed to monitor the

chemical reactions that occur during processing polymer composites and subsequent to processing (post-cure). Using this

technique the effects of initiator type and concentration as well as the molecular flexibility of the prepolymers have been

investigated. The degree of post-curing was found to be affected

primarily by the molecular flexibility of the prepolymer.

ADDITIVE MIGRATION AND CHEMICAL DURABILITY OF POLYMERS

Task 12138

• Kinetic data on the production of acidic groups in the hydrolysis of crossl inked polyester polyurethanes and polyethylene

terephthalate have been measured. These data are being used in

kinetic schemes recently developed at NBS to predict the lifetimes of these polymers when used as base materials and magnetic

tape binders to store archival information. The information

provides far more realistic estimates of when archival material

should be recopied.

• Thermal degradation occurs during the processing stage for many

polymer-based materials. Activation energies and a kinetic

scheme for thermal degradation have been provided for polyisobutylene using a thermogravimetric technique deveoped at NBS. The

important effect of pressure on volatile production and on the

measured kinetic values used to estimate the extent of thermal

degradation has been demonstrated by means of calculation and

experimental data. New thermogravimetric techniques have been

developed which greatly ease the characterization of degradation

mechani sms.

• The relative contributions of thermal and photolytic degradation

in PMMA used as solar cover plate materials are being elucidated

by first exposing the materials to controlled environments and

then determining the molecular weight as a function of depth in

a series of highly precise measurements. The contributions of

other factors to the degradation will be examined in a continuing

series of experiments. The aim is to predict molecular weight

changes as a function of exposure. This will make it possible

to estimate changes in mechanical properties with exposure.

• Highly sensitive fluorescence techniques have been developed to

provide measurements on migration rates, and have been applied

563-9
to: (1) measurement of the migration rate of an amine antioxidant from low density polyethylene, and (2) translation diffusion of chain molecules in semi-dilute solution. The second

area provides data needed for tests of the scaling and reptation

concepts proposed by de Gennes.

• An inverse phase gas chromatographic technique has been developed

and applied to the measurement of diffusi vi ties of several migrants

in high density polyethylene. Such data are used in modelling

the rate of loss of plasticizers and stabilizers from polymeric

materials.

MICROSTRUCTURE AND PERFORMANCE OF DIELECTRIC PLASTICS

Task 12139

• A new time domain dielectric spectrometer has been developed.

It rapidly measures and transforms charge-time data to dielectric

constant and loss as a function of frequency over the range from

10-3 to 10 5 Hz. This measurement technique, which meets an industrial need for rapid and accurate measurement over a wide

frequency range, will be adapted for industrial use by a Research Associate from G.E.

• A major review of data and mechanisms for dielectric loss in

materials at microwave frequencies was prepared for the U.S.

Army Civil Engineering Research Laboratory. This data is

needed to better understand and control the reflection of micro- waves from solid structure.

• A ferroelectric to paraelectric transition in a copolymer of

vinylidene fluoride and trifluoroethylene was shown to be due

to a change in conformation of the chain within the crystal

phase of the polymer. Such conformational changes have important

implications on the long-term, high temperature durability of

piezoelectric polymeric transducers. This work was done in a cooperative project with Bell Laboratories.

• The NBS-perfected technique for measuring space charge and polarization distribution in a thin polymer film has been successfully

applied to electron-beam charged PVC and to PVDF after reversal

of the poling field. Polymer-charge interactions leading to

nonuniform electric fields are believed to play a key role in

the performance of insulating materials.

• The use of polyvinylidene fluoride piezoelectric and pyroelectric transducers at elevated temperatures is limited to about

100 °C due to loss of polarization although the melting point

of the polymer is near 170 °C. A rapid method for measuring

pyroelectric response as a function of temperature has been

developed as a first step in determining the variables which

influence this loss in order to provide the basis for improved

high temperature performance. This work was done in collaboration with the Brown Research Foundation.

563-10
• The processing conditions required to produce thick films of

polyvinylidene fluoride transducers for sensitive hydrophones

were successfully demonstrated to the Naval Ocean Systems Command.

These thick films are most promising for hydrophone applications.

• Piezoelectric polymer sensors produced at NBS are being evalu-

- ated as monitors in cardiac patients in collaboration with the

CNR Institute of Clinical Physiology.

• With support from the Office of Naval Research, NBS has initiated

a long-range investigation into the relation between morphology

and structure of polymers and the highly specific property of

fast ion transport. These types of polymers have potentially

high payoff applications as solid state electrolytes in batteries

and fuel cells and as highly specific electrochemical sensors.

• At the request of the Department of Energy, an NBS evaluation has

shown that electrical resistivity changes in cellulose acetate

after neutron irradiation would not be useful as an effective

neutron dosimeter. This conclusion is contrary to a report published by another laboratory.

In the following pages, the activities of the Division are presented

formally in six tasks, each described separately:

12132 POLYMER STANDARDS FOR PROCESS CONTROL AND EQUITY

12135 TESTS, STANDARDS, AND CHARACTERIZATION FOR MANUFACTURING AND

DURABILITY OF DENTAL AND MEDICAL MATERIALS

12136 MECHANICAL DURABILITY OF POLYMERS

12137 PROCESSING AND RELIABILITY OF POLYMER COMPOSITES

12138 ADDITIVE MIGRATION AND CHEMICAL DURABILITY OF POLYMERS

12139 MICROSTRUCTURE AND PERFORMANCE OF DIELECTRIC PLASTICS.

563-11
'
POLYMER STANDARDS FOR PROCESS CONTROL AND EQUITY

Task 12132

This task provides standard reference materials (SRMs) to the $30 B/year

synthetic polymers producing industry. Molecular weight SRMs are used

extensively in industry to calibrate gel permeation chromatographs

(GPCs) which are used routinely to measure polymer molecular weights and

molecular weight distributions. The latter are the most important

physical feature in determining a polymer's processability and its

ultimate performance. Gas transmission and rubber SRMs are used in

process control applications.

Improved characterization techniques are essential to providing improved

SRMs. A fundamental knowledge of polymer solution properties such as osmotic pressure, viscosity, diffusional behavior, and scattering power

is essential to this goal. As a consequence, a majority of the activities

in this task involve experimental and theoretical studies of polymer

solution properties. As a spinoff of our characterization activities,

this task also provides data and concepts which are useful in polymer

processi ng.

The execution of this task was assisted by Dr. D. Lohse, an industrial

research associate from Exxon, Dr. J. G. Dillon, a guest worker from the

Food and Drug Administration, and A. Z. Akcasu, a guest worker from the

University of Wisconsin.

Self-Calibrating Gel Permeation Chromatography

Subtask 1 of Task 12132

P. H. Verdier

Gel permeating chromatography is a widely accepted technique for estimating

the molecular weight distribution (MWD) of high polymers. However, the

usefulness of the conventional GPC apparatus is limited by the need to

provide cal i brants for each polymer measured of known molecular weight

over the entire molecular weight range in which the MWD is significantly

different from zero. The calibration depends, among other things, upon

the chemical nature, degree of branching, etc., of the polymeric material

so that each new material requires a fresh calibration. The so-called

"universal calibration" hypothesis, while useful, is limited to comparisons of polymers of similar shape and, in any event, is inadequate for

quantitative determinations. Some instruments, one of which is commer- cially available, attempt to circumvent the need for cal i brants by

adding a single-angle light scattering detector to the usual concentration-sensitive detector. However, this does not allow the extrapolation

to zero scattering angle which is required, in principle, to relate

scattering intensity to molecular weight. In addition, qualitative

information on the variation of scattering with angle, normally required

to give assurance that meaningful results are being obtained, is not

available.

We are designing and constructing a light scattering detector for the

GPC which measures, in real time, the scattering intensity as a function

of scattering angle and which is controlled by a dedicated minicomputer

563-13
in a way that allows scattering to be measured as a function of scattering

angle and concentration. The instrument will allow continuous monitoring

of the variation of scattering with angle. This will allow immediate

identification of difficulties such as association, microgel formation,

etc., which could affect the validity of the molecular weight obtained,

an important consideration for work on new and unstudied materials. In

addition to molecular weight, the mean-square radius (radius of gyration)

will be obtained as a function of molecular weight, at least in the

higher ranges of molecular weight, providing useful information for the

characterization of branched polymers.

We expect to complete construction of the instrument by the end of FY82.

In the coming year, we will start making measurements with it and developing procedures for high-quality molecular weight determinations.

Liquid Size Exclusion Chromatography

Subtask 2 of Task 12132

H. L. Wagner and J. D. Barnes

A commercial high performance liquid size exclusion chromatograph has

been installed for the determination of the molecular weight and molecular

weight distribution of polymer samples. The apparatus has been automated

and may be operated at temperatures up to 150 °C, the temperature required

for the dissolution of polyethylene and certain other crystalline polymers.

The unit is self-contained so that as many as 16 samples may be prepared

internally. The conditions for each sample may be programmed separately

and as many as nine replicate injections are possible. In conjunction

with the automated data acquisition system, it is possible to run for over a 24 hour period without operator attention. The actual time

required will depend on the columns and time allowed between runs for

sample preparation and data acquisition.

The software has been designed so that the user does not need to learn

the operating system of the computer and so that there is a one-to-one

correspondence between the data required to program the chromatograph

(which is microprocessor controlled) and that required to perform data

analyses in the computer. Graphics and database capabilities are built

into the software to allow the user easy interpretation of the data once

it is collected.

This facility will be employed for many of the problems encountered in

the Polymer Science and Standards Division where molecular weight distribution is a controlling variable. Changes in molecular weight distribution have been found to correlate with changes in many physical properties

such as tensile strength, modulus, relaxation times, elongation, and

stress cracking. The equipment has already been employed successfully

in support of a project for the NBS Center for Building Technology

involving the affect of ultraviolet exposure on polymethyl methacrylate.

563-14
Limiting Viscosity Number of Ultrahigh Molecular Weight Polyethylene

Subtask 3 of Task 12132

H. L. Wagner and J. G. Dillon

Limiting viscosity number (intrinsic viscosity) measurements are required

for the specification and control of ultrahigh molecular weight polyethylene (UHMWPE), one of the most extensively employed surgical implant

materials. Because the viscosity number is dependent on shear rate, it

should be measured at zero or very low shear rates where this dependency

does not occur. For this purpose a low shear rate viscometer capable of

being operated at high temperatures (135 to 145 °C) was constructed.

The problems associated with the viscometer and some of the measurement

difficulties, described in previous reports, have been overcome.

This type of viscometer is not commercially available and requires more

than routine skill for its operation. However capillary viscometers, in

which the shear rate can be quite high, have been successfully employed

for many years for lower molecular weight polymers which are not sensitive

to shear rate. A set of experiments were performed in which the same solutions, fraction of UHMWPE, were measured in decal in at 135 °C in

both the low shear viscometer and a commercial capillary viscometer

which is of a standard design. As shown in figure 1 an empirical relation

exists between the two, so that a routine capillary viscometer measurement

may be used to estimate the low shear value provided the capillary

viscometer is of the same capillary size and volume as used in these

experiments.

The measurements were made on fractions of UHMWPE obtained by the method

described below. In order to assure complete dissolution of these fractions it was necessary to cut the material into 1/2 mm bits and to heat

in decal in at 180 °C under nitrogen for one hour, with occasional gentle

mixing to prevent agglomeration of the bits. This method was successful

with all but the highest molecular weight fraction. The poor reproducibility of the results for this fraction, where viscosity numbers were of

the order of 60 dl/g, indicates that solution was incomplete. From 4 to

8 measurements were made for each of 10 fractions to determine the

limiting viscosity number of each fraction. These ranged from 9 to

52 dl/g.

These or similar fractions will be used to obtain the relationship

between molecular weight and viscosity numbers by light scattering for * these very high molecular weight polyethylenes. The Mark Houwink relation between viscosity and molecular weight, obtained emperically for

lower molecular weight polymers, is not expected to hold for UHMWPE.

When this relation is available, it should be possible to obtain molecular

weights from simple capillary viscosity measurements in a standard

vi scometer.

563-15
Fractionation of Ultrahigh Molecular Weight Polyethylene

Subtask 4 of Task 12132

H. L. Wagner

The fractions described above were obtained by crystallization from a

1 percent solution of UHMWPE in decal in. This solution was cooled

slowly from 135 °C with rapid stirring until polymer appeared on the

stirrer. This fraction was removed and the process was repeated until

the next fraction appeared. Ten fractions were obtained by this method.

About 12 percent of the material did not precipitate by the stirring

process and was recovered as a residue when the solution was cooled.

Limiting viscosity numbers ranged from 9 dl/g to 50 dl/g in decalin at

135 °C. Employing the conventional Mark Houwink relationship for lower

molecular weight polymers this corresponds to a range of from about

900,000 to 10 million in molecular weight. The viscosity average molecular

weight for the residue, if calculated in this way, is about 700,000 and

would be expected to be very broad in distinction. This was confirmed

in a preliminary GPC run which indicated the presence of material below

10,000, as well as some above 1 million.

Analysis of Ultracentrifugation Interference Patterns with Image Digitizer : Application to Molecular Weight Determination of SRM 1478 Polystyrene

Subtask 5 of Task 12132

F. W. Wang and F. L. McCrackin

A new method for the analysis of ultracentrifugation interference patterns

with the use of a commercial image digitizer is given. The application

of the method to the sedimentation equilibrium data for SRM 1478 Polystyrene leads to a weight-average molecular weight of 37,400 g/mol having a sample standard deviation of 0.7 percent and expected systematic error

limit of 2 percent.

Standards for Gas Transmission Measurements

Subtask 6 of Task 12132

J. D. Barnes

Gas transport properties of polymeric materials are the major determinant

of suitability for end use in a great variety of applications ranging

from food and beverage packaging, industrial gas separation processes,

and sterilization of medical devices, to substrates and packages for

semiconductor products. Gas molecules are useful as probes of materials

properties at the microstructural level. The measurement system for gas

transport properties has suffered from a lack of reliable standards.

NBS is addressing these needs by developing improved measurement technology

and by characterizing polymeric materials for use as Standard Reference

Materials. The certification of SRM 1470 for its gas transmission

properties with respect to helium, carbon dioxide, oxygen, and nitrogen

has been completed. It is expected that this material will now be

useful to a wider variety of users.

563-16
The recertification experiments produced approximately 720 values of the

permeance and 540 values of the time-lag (the time-lag for helium was

too short to measure). The results can be summarized in the form:

Q (T) = Q (23) x exp(p

Q

[T - 23]) , (1)

where the """ denotes that the quantity is an estimated value as derived

from fitting to the experimental data. "Q" represents either the permeance, P, or the time-lag, x, as appropriate and T is the temperature of

measurement in °C. Values of Q (23) and obtained from the analysis

of the permeance and the time-lag data are^given in tables 1 and 2

respectively. Since the time-lag for carbon dioxide depends upon the

upstream pressure it is necessary to multiply the estimates obtained

from equation 1 by a term of the form:

exp[a

1 (p u -101.32) + a2 (pu -101. 32)

2

] , (2)

where the upstream pressure, p

u

, is expressed in kPa. Estimates derived

from equations (1) and (2) are valid only for pressures between 67.5 and

135 kPa and for temperatures between 18 and 31 °C, the ranges covered in our experiments.

Tables 1 and 2 provide additional statistical data that can be used to

qualify the estimates derived from the fitting process. C is the

M

coefficient of variation of the expected value, its numerical value

largely determined by the sampling error arising from the selection of

test specimens. C

s

, the coefficient of variation of the "specimen

effects," is a measure of the inhomogeneity of the lot of SRM material.

C , the coefficient of variation of the residuals from the fit, is a

r measure of the extent to which individual data values depart from the

model in equation (1). We have chosen not to construct the usual confidence or tolerance intervals because we do not have enough data on the

distribution of the specimen effects. We are studying additional specimens

to better define the structure and distribution of the specimen effects.

We are also seeking simple auxiliary measurements such as the specimen

thickness or the density that can be used to define correction factors

for reducing the measured values to a common basis. In the absence of

such a scheme the specimen-to-specimen variability is the dominant

factor limiting the precision that can be expected when comparing measurements among different stations in a measurement system.

The observed decrease of the time-lag for carbon dioxide with increasing

pressure is consistent with published data that have been interpreted

using a "partial immobilization" model. It is somewhat surprising that

we do not observe a concommitant decrease in the permeance; perhaps the

pressures used are too low or the pressure range is not broad enough.

The effects of partial immobilization are small in the range of conditions

covered in our experiments. Users who wish to carry out measurements at

much higher pressures and temperatures should realize that they may have

to take explicit account of this phenomenon.

563-17
We are modifying our apparatus to operate at higher pressures and at

temperatures encompassing the glass transition of poly(ethyl ene terephthalate) (PET) in order to better characterize the physics of partial

immobilization and its relationship to the glass transition.

We are working to identify needs for materials with transmission rates

that are both higher and lower than those of SRM 1470.

Since it is difficult to control processes for making plastic films in

order to limit variability in their physical properties to one percent

or less, we find that material inhomogeneity is an obstacle to the

development of better SRMs. It is also difficult to use such materials

as transfer standards because their characteristics often drift with

time and test specimens often do not tolerate abuse suffered during the

measuring process.

We have modified the software for our computer-controlled gas transmission

measuring facility so that plotting of the raw data and reduction of the

data to permeance and time-lag values are done on-line at the conclusion

of each experiment. The software generates databases that can be input

directly into statistical analysis programs over an NBS Net TIE.

New data acquisition hardware has allowed us to measure time-lags of

less than one second. Further work must be done to detect the presence

of instrumental time constants that can interfere with the measurement

of the diffusion time-lags of the materials.

Table 1

Fit Results for Permeance Data

Parameter N

2

Gas

°2 co

2

He Units

P ( 23 ) .0421 .352 1.722 13.79

2 pmol/m *s*Pa

ep .0521 .0376 .0309 .0287 1/K

C

M

.023 .014 .018 .012

C

s .057 .045 .056 .037

C

r .050 .017 .010 .009

563-18
Table 2

Fit Results for Time-Lag Data

Gas

Parameter °2 N

2

CO

2

Units

t(23) 388. 1792. 2160. sec.

e. -0.0597 -0.0763 -0.0624 1/K

C 0.013 0.022 0.014

M

C

s 0.039 0.067 0.042

C 0.024 0.094 0.016

r 2

a-,xlO^

a^xlO^

-0.1873

0.0911

1/kPa.

l/(kPa.) 2

Diffusion of Polymers in Semi dilute Solutions by Dynamic Light Scattering

Subtask 7 of Task 12132

E. J. Amis, C. C. Han, and Y. Matsushita

The quasi elastic light scattering from semi dilute solutions of polystyrene

in both good or theta solvent conditions has been measured as a function

of molecular weight and concentration. We observe two distinct exponential decays separated by several orders of magnitude. The angular

dependence of the decay constants is indicative of diffusive processes

which we identify with the cooperative diffusion coefficient, D

c and the

self-diffusion coefficient D . It is found that D , identified with the

s c’

fast decay, increases with polystyrene concentration and is almost

independent of molecular weight. D

$ on the other hand decreases sharply

with concentration and molecular weight. An explanation of the light

scattering detection of these two diffusion coefficients can be made

which is based only on assumptions inherent in the reptation model of

diffusion in semi dilute solutions. Over the range of molecular weight

and concentration accessible to the technique the theta condition,

measurements of D

g are in good agreement with scaling predictions of D$ a M

2 c' 3

. For the good solvent measurements, the agreement with the

prediction of D

$ a M

2 c

_1 75 is only observed for a narrow window. The

blob model gives some explanation for this behavior by allowing that

even in a good solvent there is some distance below which excluded

volume is unimportant. The chain is Gaussian and the chain shows thetalike (D

g a c -3

) behavior. The blob model is however unable to account

for the fact that for D

c the agreement with predictions is much better

563-19
in good solvent than in theta solvent. These experiments point out, once again, that the degree of agreement with scaling predictions is

very much dependent on the concentration and molecular-weight ranges,

the solvent quality, the property being examined, and the type of measurement.

Forced Rayleigh Scattering

Subtask 8 of Task 12132

E. J. Amis and C. C. Han

So far this project has been limited to the construction of new instrumentation. In this technique a split laser beam is recombined at a small

crossing angle on a sample which includes a trace of polymer labeled

with a photochromic dye. This "writing" beam is pulsed to produce an interference pattern which bleaches a holographic grating in the sample.

A second laser beam "reads" this pattern and is diffracted by the grating.

As the labeled polymers diffuse in the sample, the grating is destroyed

and thus, by measuring the intensity decay of the diffracted beam, the

tracer diffusion coefficient of the labeled species can be obtained.

Since the distance scale of this tracer method is very small (typically

several orders of magnitude smaller than macroscopic tracer methods) it

is possible to measure extremely small diffusion coefficients such as those expected for polymer molecules in concentrated solutions and

melts. Recent theories of dynamics in concentrated solutions and melts

should be tested by this experiment. Preliminary tests of the instrument

have been very encouraging and with the installation of the detector

electronics this instrument will be complete. Initial experiments will

include measurement of free dye and small labeled polymers through

dilute, semidilute, and concentrated solutions of various molecular

weight polymers.

Concentration and Polydispersi ty Dependence of the Static Structure Factor

S(q,c) and the Dynamic Characteristic Frequency, Q(q,c) in Dilute Polymer

Sol utions

Subtask 9 of Task 12132

A. Z. Akcasu, B. Hammouda, T. P. Lodge, and C. C. Han

In all polymer characterization measurements, single chain properties

such as the molecular weight and radius of gyration are obtained through

extrapolation to zero concentration of measurements carried out at

finite concentrations. It is clear that measurement precision can be

greatly improved if single chain properties can be extracted directly

from measurements carried out at finite concentrations and various

polydispersities. It will be especially useful if scattering angle

extrapolation can also be avoided in a scattering experiment. In this

work, theoretical shape functions of static structure factor as a function

of the scattering vector, q, and concentration, c, are developed and tested

through light and neutron scattering data. Also, calculations of the

dynamic characteristic frequency Q(q,c) and decay rates are performed for

polydispersed systems and compared to dynamic light-scattering data at the

0 temperature.

563-20
Single Chain Conformation in Phase Separated Pi block Copolymer Systems

Subtask 10 of Task 12132

H. Hasegawa, E. J. Amis, T. P. Lodge, and C. C. Han

Polymer properties can be greatly altered by controlling the size and

shape of the phase separated domains of polymer blends or copolymer

systems. It is obvious that the single chain statistics in these phase

separated domains play an important role in the understanding of the

equilibrium and nonequilibrium properties of these systems. In collaboration with Dr. H. Hasegawa and the Kyoto University group, we have

prepared well controlled model systems of polystyrene-polyisoprene which

have regular lamella domains. Dimensions of deuterium labeled polystyrene

block of this diblock copolymer and also dispersed homopolystyrene

molecules were measured at different directions relative to the domain

orientations by small -angle neutron scattering (SANS).

Small Angle Neutron Scattering From Block Copolymers of h-styrene and

d- styrene

Subtask 11 of Task 12132

T. P. Lodge, Y. Matsushita, E. J. Amis, and C. C. Han

In our effort to investigate the temperature and molecular weight dependence of polymer dimensions, various experiments and theoretical models

have been investigated. It is true that the chain end effects are normally

neglected in both mean field and modern scaling theories. Although

perturbation theory attempts to differentiate the excluded volume effect

as a function along the chain contour, it is not expected to work well

in the good solvent limit. In this work, we performed SANS measurements

of labeled chain segments located at various positions along the chain

contour. As far as we know, this is the first time the importance (or

unimportance) of neglecting the chain end effect has been tested experimentally through direct measurements of a set of well prepared and well

characterized polymer samples.

Static Light Scattering

Subtask 12 of Task 12132

C. C. Han, H. L. Wagner, and D. B. Minor

The light scattering photometer has been redesigned and fabrication has

been completed. Preliminary measurements show that the problem of

thermal instability has been overcome because of a new highly stable

rotory table and isolation of the high temperature bath from the optical

train. Other features which have been incorporated are a stepping motor

drive for the rotory table, and a 4 MW He-Ne laser rather than the 2 MW

one used previously.

563-21
Dynamics of Polymer Chains

Subtask 13 of Task 12132

P. H. Verdier and D. E. Kranbuehl

The dynamic behavior of polymer chains is important to improving both

characterization and processibi 1 ity of polymers. The principal methods

used to estimate molecular weight, and in particular gel permeating

chromatography, the only method available at present for estimating

distribution in molecular weight, are dynamical, nonequilibrium experiments which depend in part upon the relaxation of polymer chains in

dilute solution. In its present state, the theory of these systems does

not allow the calculation of molecular weight directly from measured

quantities; a series of cal i brants of known molecular weight is required.

Improvements in the theory could reduce or even remove the need for

cal i brants, allowing the determination of molecular weight distribution

of polymers for which calibrants are not available.

The processability and the final characteristics of both plastics and

elastomers depend in large part upon the relaxation behavior of the

high-polymer chains of which these materials are primarily composed.

More realistic theoretical treatments of polymer melts and elastomers,

which must start with more realistic treatment of the dynamical behavior

of the individual chains, will lead to more efficient processing and

better fabricated end products. A major shortcoming of the present

theory is its inability to treat chain entanglements in a realistic way.

Our present work is aimed primarily at the study of entanglement effects,

using a combination of analytical and computer simulation techniques.

The simulation results provide data on simple model systems and serve to

guide the development of better theoretical treatments.

Work in this area is proceeding along two main lines. First, there is

at present an unresolved disagreement in the literature regarding the

interpretation of the time-correlation functions obtained for flexible

chain molecules in the quasi elastic light scattering experiment. It is

not clear whether these functions exhibit the entire spectrum of chain

relaxation times or are dominated by the longest relaxation time. By a combination of analytical and simulation techniques, we have shown that

very slight changes in the local chain-movement rules can change the

behavior of the resulting time-correlation functions from one extreme to

the other, suggesting that the existing disagreement is due at least in

part to the use of insufficiently detailed chain models. These results

will be published during the coming year. Second, as a step in the

direction of investigation melt properties, we are carrying out simulation

studies of systems of many interacting chains, with chain densities

corresponding to concentrated solutions and melts. Interpretation of

the results of these studies is underway, and will continue in the

coming year.

563-22
Monte Carlo Calculations of the Hydrodynamic Radii of Polymers

Subtask 14 of Task 12132

F. L. McCrackin

s The values of the hydrodynamic radii of chains at infinite dilution on a cubic lattice were computed. The chains were created by a Monte Carlo

simulation in which both volume exclusion and energetics of nearest

neighbor interactions were taken into account. Other quantities, such

as radii of gyration, were also computed for the chains. The ratio p,

the radius of gyration to the hydrodynamic radius of the chains at the

theta point, were compared to experimental values obtained from quasielastic light scattering and elastic light and neutron scattering. Reasonable

agreement was obtained; in fact, the experimental values of p showed

better agreement with the Monte Carlo calculation than with the analytical

Gaussian coil model.

The calculations were also performed for various values of the energy

parameter, corresponding to good solvents. The computed values of the

hydrodynamic radius are found to be in reasonable agreement with published

data of the variation hydrodynamic radius of polystyrene with temperature.

The results are also in agreement with calculations of A. Z. Akcasu

based on the blob model of polymer solutions.

The calculations are being performed for two interacting chains. The

results will be interpreted as the properties of polymers in dilute

solutions. The variation of radii of gyration and hydrodynamic radii

with concentration and the second virial coefficient will be calculated

and compared with experiment.

Span of an Adsorbed Random Flight Chain Calculated on the Basis of the

deGennes Model

Subtask 15 of Task 12132

R. J. Rubin

P. deGennes showed that the one-dimensional step density distribution of

monomers in his model (normalized to N, the number of monomers) is

-?kv

n(x) = 2kNe , for k>0 , (3)

where x is the distance from the solution surface, and the boundary

condition of the random flight propagator at the solution surface is

1/G aG/3x| x=0 = -k.

G. Weiss and I have derived the probability density of the span of an adsorbed polymer chain in deGenne's model. The average value of the

span is

<X> = (2k)”

1

£nN for N»l.

This quantity is identically equal to the distance from the adsorbing

solution surface at which the exponential step density given in Eq. (3)

is equal to unity, i.e., if the equation

563-23
— 2 kx

2kNe , = 1

is solved for x lt then x x = <x>. A paper outlining this calculation of

the probability density of the span has been prepared and submitted for

review.

Validation pf the "Weak Adsorption" Diffusion Equation Plus Boundary

Condition Model of deGennes

Subtask 16 of Task 12132

R. J. Rubin

We have solved the discrete lattice random walk model for a polymer

chain near a surface when there is an absorbing layer at K = -1 and each

segment of a chain configuration in layers K = 0 to £ results in a

e / kT Boltzmann weighting factor e multiplying the probability of that

configuration, [e is the energy gained when any chain segment occupies

any one of these £ + 1 layers. Thus, the weighting factor of a chain

me / kT configuration in which m segments lie in layers k = 0 to £ is e .]

We have solved the analogous diffusion equation model for this problem

[this diffusion equation was first proposed by J. Pouchly' , Coll. Czech.

Chem. Comm. 28: 1804; 1963]. The deGennes model may be regarded as a limit of the Pouchly' model which in turn is the continuous analog of

the discrete model described above. A paper comparing polymer chain

behavior in these models is in preparation.

A New Equation of State Model for Polymers

Subtask 17 of Task 12132

I. C. Sanchez

A new statistical mechanical model for a chain liquid has been developed

which shows sol id-1 iquid transition as well as a liquid-vapor transition.

This new model is a generalization of the lattice fluid model developed

by Sanchez and Lacombe. The basic idea is that the mers of a r-mer can exist in either of two states: ordered or disordered. In order for an r-mer to crystallize it must be in a particular orientation. For example,

in an alkane the monomers must all be in a trans configuration to crystallize. Or if the mers have a permanent dipole, they would all have to be

oriented correctly to crystallize.

We are exploring several different applications for this model. First

it may prove to be an excellent model for describing glassy behavior in

polymers. It should also be a good model for describing polar polymer

mixtures that strongly interact. Finally, it may prove to be a relatively

simple model that will be able to semiquantitatively describe the PVT

properties of water.

563-24
ASTM Activities

Subtask 18 of Task 12132

I

I J. D. Barnes

J. D. Barnes serves as Chairman of ASTM Subcommittee F-2.93 and D-20.13.

These subcommittees provide assistance in matters relating to the design

of experiments for evaluating the precision of test methods for the

parent ASTM Committees. This assistance takes the form of approval of

round-robin protocols, critique of precision statements, and statistical

education for task group leaders. Recent round-robin activities have

included a test method for Bond Strength within Committee F-2 and a study of the density gradient technique (ASTM D-1505) for Committee

D-20. Dr. Barnes has served as a consultant to task groups working on Rockwell hardness of plastics, tensile properties of film and sheeting,

and thickness measurements using a magnetic sensor.

Dr. Barnes has recently been appointed Chairman of Subcommittee D-20. 70'

section on gas transmission measurements.

Dr. Barnes organized a symposium on Fourier transform infrared (FTIR)

methods in plastics characterization and processing that attracted five

invited papers that were heard by about 75 participants at an ASTM meeting

in Williamsburg, VA.

Rubber and Rubber Compounding Standard Reference Materials

Subtask 19 of Task 12132

G. B. McKenna and G. W. Bullman

NBS provides rubber and rubber compounding Standard Reference Materials

that are used by the rubber industry for quality control in production

of rubber and its processing into articles. During the past year recertification of SRMs 371 (Sulfur) and 372 (Stearic Acid) have been completed.

These compounding materials are referenced in ASTM standards and used to ensure the processibi 1 ity of rubber materials. The Mooney viscosity

standard, SRM 388, butyl rubber, has also been renewed during the past

year. This standard is widely used by the rubber industry for calibration

of Mooney Viscometers which are increasingly used for on-line quality

control during the production of synthetic rubbers.

563-25
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563-26

CAPILLARYLVN

DL/G
TESTS, STANDARDS AND CHARACTERIZATION FOR MANUFACTURING AND DURABILITY

OF DENTAL AND MEDICAL MATERIALS

Task 12135

The objective of this research is to provide test methods and standards

to sectors of the health care industry that make critical use of materials.

Materials research and techniques are pursued with the goal of developing

dental adhesive composite restorative materials of greater durability and

wear resistance, improved base metal alloy alternatives to the costly gold

alloy dental prostheses, and test methodology applicable to porcelain/alloy

combinations. Knowledge of the structure and physical chemistry of

biologically important calcium phosphates is used to develop improved preventive dental techniques. Improved test methodology is sought for

characterization of the surfaces of surgical implant materials for defining

the interactions that occur thereon. Means for characterizing the porosity

of low modulus, polymeric, medical implant materials are being investigated.

Dental research directions in support of the objective are established

col laboratively with the American Dental Association, the National

Institute of Dental Research, and the Department of Defense Medical R&D

Command. Medical materials research is guided by close interaction with

the Bureau of Medical Devices, Food and Drug Administration, and the

ASTM F-4 Committee (Medical and Surgical Materials and Devices.)

Dental Composite Chemistry and Development

Subtask 1 of Task 12135

G. M. Brauer, J. M. Antonucci , J. W. Stansbury, J. M. Cassel , S. Ventz 1

, and R. L. Bowen2

x Guest Worker, Free University of Berlin

2 Research Associate, American Dental Association

With the view that reducing polymerization shrinkage and residual

unsaturation in dental resin systems would make them more useful in

efforts to achieve adhesive bonding, better color stability, and improved

durability in composite restorative systems, we have continued to investigate new comonomer combinations whose structures would suggest their

applicability for this purpose. A particularly promising monomer is the

high molecular weight, moderately viscous polythiol pentaerythritol

tetra (3-mercaptophopropionate) (PETMP). It has potential not only as a useful comonomer but also as a polymerization accelerator. With multifunctional methacrylates that readily undergo free radical self-addition

reactions of vinyl groups to create a propagating polymeric chain, the

use of polythiols leads to a hybrid polymer composed of polymethacrylate

and polythioether elements in the network structure. Preliminary results

using infrared spectroscopy indicate there is a significant reduction in

vinyl unsaturation when modest concentrations (< 5 percent by weight) of

PETMP are employed in a typical dental resin formulation. Levels of

PETMP between 1 and 5 percent have produced composite materials with

excellent esthetics and color stability. The improvement in color

stability and esthetics in many of the resin systems examined may be due

563-27
to the fact that use of PETMP allows a reduction in the concentration of

amine accelerator, a recognized source of color problems with composite

restorations. A further important potential advantage to be explored

with PETMP is that it appears to enhance the storage stability in the

dissolved state of such highly biocompatible polymerization promotors as ascorbic acid.

We have found the bulky monomethacrylate, isobornyl methacrylate (IBM) can

be used to dilute 2,2-bis[P-(2-hydroxy-3-methacryloxy-propoxy)phenylene]-

propane (BIS-GMA) and composites with good setting characteristics, color and mechanical properties are obtained. Unlike many long

chain alkyl methacrylates that have sluggish ambient temperature rates

of polymerization, IBM is more reactive even than methyl methacrylate.

Homopolymers of IBM in contrast to other alkyl methacrylates have a slightly higher glass transition temperature (T ) than that for poly(methyl

9

methacrylate) (PMMA) and this may prove advantageous in developing greater

durability in composite restorations. However, when used as a comonomer

with a hydrophobic, highly fluorinated polymethacrylate for purposes of

reducing water sorption, the IBM appears to yield only marginal strength

composites.

Our previous investigation of the silanization treatment of composite

filler particles had shown that incorporating certain n-alkyl amines and

selecting a hydrocarbon carrier for 3-methacryloxypropyltrimethoxysilane

increased the reinforcing capability of the filler particles. This

beneficial effect has now been shown to be optimized using a 2 percent

solution of n-propyl amine and 0.5 percent of silanizing agent in cyclohexane. Initial tensile strengths of composites is improved significantly

and the rate of water- induced loss of strength as determined for two and

six months at 37 °C is reduced.

Improved Bonding Techniques and New Dental Cements

Subtask 2 of Task 12135

G. M. Brauer, R. L. Bowen 1

, J. M. Antonucci , J. W. Stansbury, D. W. Misra 1

, E. Cobb2

, and J. M. Cassel

Research Associate, American Dental Association

2 Guest Worker, Georgetown University School of Dentistry

While effective bonding to tooth enamel is presently achieved by means

of acid etch treatments, similar treatments of dentin have not shown

satisfactory results. We are currently investigating several potential means of resolving this problem.

A1 kyl cyanoacrylates polymerize rapidly at room temperature and certain

ones have been previously shown to yield a very strong initial bond with

dentin that unfortunately is weakened significantly on exposure to

water. To address this shortcoming we have begun an effort to prepare a cyanoacrylate with cross-linking capability, i.e., allyl 2-cyanoacrylate.

The synthesis involved esterification of cyanoacetic acid to allyl

cyanoacetate which was then reacted with paraformaldehyde to give poly

(allyl 2-cyanoacrylate). While we have made repeated efforts to depolymeri

563-28
this polymer to yield the desired monomer, we have not been successful

to date and currently we are examining alternative means for its preparation.

A new bonding procedure that uses an acid mordanting solution, a surface

active- monomer, and a coupling agent to prepare dentin and enamel for

bonding to composite resins appears to have much promise. An aqueous

solution of ferric oxalate is applied, washed with water, and blown dry.

An acetone solution of the surface active comonomer NTG-GMA, the adduct

of N(p-tolyl )glycine and glycidyl methacrylate is applied, followed by

pure acetone and drying with air. An acetone solution of the addition

reaction product of pyromellitic di anhydride and 2-hydroxyethyl methacrylate

is then applied and the surface blown dry before pressing a composite

resin formulation against the surface and allowing it to harden (polymerize).

Scanning electron microscopy results show that the iron oxalate solution

alters the tooth surface layers. The coupling agents then provide

molecules which are bound to the modified surface and can polymerize

with the resin of the composite material applied subsequently. Bond

strength measurements confirm that the strong bonding initially achieved

is retained on exposure to water for up to five days. A real possibility

exists for improving treatment of erosion, root caries, and other conditions by reducing the amount of dentin that must be cut for mechanical

retention.

Dental cements with good biocompatibility, improved mechanical properties

and resistance to disintegration on exposure to the oral environment are

needed. Zinc oxide-eugenol dental cements, while possessing many desirable

properties, are relatively soluble in oral fluids and adhere poorly to

acrylic restorations, bone, or dental tissues. Furthermore, because of

the electron-rich phenolic hydroxyl group in eugenol , these cements

inhibit free radical polymerization and hence hardening in any dental

resin or composite system subsequently placed in contact. Previous

research to develop substitutes for the eugenol component has not produced

cements with adequate physical properties. Recently, however, we have

developed a non-eugenol based cement that combines zinc oxide, ethoxybenzoic acid (EBA) and esters of vanillic acid. It has been demonstrated

to have not only desired physical properties but certain important

chemical properties. These cements do not inhibit free radical polymerization, and adhere strongly, even in water, to nonprecious metals,

amalgams and composites. They do not disintegrate in water and considerably exceed the requirements of the ANSI/ADA Specification No. 30.

Thus, a portion of the cement, when used as a temporary filling, can be

retained as a base for acrylic resin restorations. The material, with

suitable modifications, looks most promising as a base, temporary restorative, and endodontic cement. Cementitious restoratives with drastically

improved mechanical properties which could find applications as longlasting temporary fillings were prepared by incorporating a di methacrylate

monomer, peroxide initiator, amine accelerator, and glass reinforcing

fillers into the cement formulations. We have prepared (by synthesis)

sufficient quantities of a promising vanillate, a hexyl vanillate, to

allow biocompatibility testing. Samples of the powder and liquid have

been sent to six institutions for biological evaluation of the basic

formulation.

563-29
To increase the strength of these cements beyond the already respectable levels achieved so that increased dental application can be made,

we have investigated cements prepared with ZnO, A1 2 03 , hydrogenated

rosin and silanized glass (coated with benzoyl peroxide) as the powder

and hexyl vanillate, decamethylene di methacrylate, a fast acting amine

accelerator and a stabilizer as the liquid. Cured cements with good

working properties and strengths, four to seven times that obtainable

with zinc oxide-eugenol formulations, were obtained. These vani 1 1 ate-based

cement modifications offer promise as intermediate restorative materials.

Wear Mechanisms, Wear Testing and Improving Durability in Dental Composite

Materials

Subtask 3 of Task 12135

W. Wu, J. E. McKinney, E. E. Toth, and J. M. Cassel

Development of improved dental restoratives requires proper evaluation

criteria to predict the long term j_n vivo performance of these materials.

Microdefect analyses involving a photographic silver staining procedure

and a small angle x-ray scattering (SAXS) technique have been applied to

quantify the extent of subsurface damage in both i_n vi vo and i_n vitro worn composite materials. Since we find that there is subsurface damage

beneath the nonstress bearing as well as the stress bearing surfaces in

clinically worn restorations, we have theorized that the oral environment

plays an important role in the deterioration process. Consequently, the

diffusion of food simulating chemical solvents into dental composites

and the influence of this diffusion in softening the polymeric matrix as

a prime step toward loss of material has been investigated.

Initial measurements of diffusion coefficients for water in typical

composites, using a quartz spring mass sorption technique, indicated that

the diffusion rates were Fickian and that both diffusion rate and water

sorption were significantly reduced in composites cured at 60 vs 37 °C.

By infrared measurement of residual double bond concentration in the

dental resin as a function of the curing time and correlation of these

results with differential scanning calorimetry measurements of the curing

that occurs as the temperature is raised from the initial 37 °C, we have

shown that the more delayed the temperature rise is, the less is the effect

on curing. This would dictate that if increased curing by heating were to

be made clinically viable, it would need to be accomplished almost immediately following placement of the restoration.

Measurements of Knoop hardness on a conventional, a strontium glass

filled, and a visible light activated composite after each was cured at

37 °C and subjected to immersion in food simulating solvents for one week demonstrated that each was softened to the greatest extent by 75 percent ethanol/water concentrations. The largest effects at this ethanol

concentration were observed with the conventional composite and the least

with the light activated material. Immediately following completion of

the immersion in the food simulating solvents, wear measurements were

made using pin on disc wear equipment. While the wear analysis is not

completed, the wear for both the conventional and the light activated

composites when plotted against the solubility parameter of the food

563-30
simulating medium follow the same trend, e.g., maximum wear rates at

75 percent ethanol concentration, as observed with the Knoop hardness

measurements. When the i_n vitro wear rates of composites cured at 25 and

60 °C and then immersed in 75 percent ethanol in water media were compared,

the wear rates of the composites cured at the

higher temperature were one-fourth that of the lower temperature-cured

material. These results are in perfect accord with the preliminary

diffusion data referred to earlier and support our contention that ways

(heat or otherwise) must be found to significantly increase the degree

of polymerization in the composite resin during the restoration process.

Composite Restorative Materials

Subtask 4 of Task 12135

J. M. Antonucci , G. M. Brauer, S. Venz 1

, N. W. Rupp2, and J. M. Cassel

1 Guest Worker, Freie Universitat of Berlin

2 Research Associate, American Dental Association

Restorative dentistry is that form of dental practice that utilizes

the most time of the Army dentist as well as the soldier dental patient.

Composite materials are prime components in restoration procedures.

Greater durability and satisfaction would be achieved with such materials

if the marginal adaptation (resistance to microleakage) were improved.

For the Army it is also important to improve the storage stability of

such materials and earlier efforts in this project have defined the

prime sources of storage instability and practical means for optimizing

storage stability with presently available materials.

This year we have demonstrated the improved sensitivity in microleakage measurement that can be achieved by using a silver staining

technique as an alternative to a more cumbersome radiotracer x-ray film

procedures. Microleakage determinations have been made on a series of

experimental composites formulated to be hydrophobic rather than mildly

hydrophilic as are current commercial dental composite materials. While

a dual silanization procedure for fluorinating as well as silanizing

glass filler particles did not reduce water sorption in the composite,

the increased compatibility of such glass with fluorinated monomers may

offer a means of achieving higher filler loadings and hence improved

physical properties if needed. Combining a commercially available

fluorinated diluent comonomer, pentadecaf 1 uoroctyl methacrylate, with

two commercially available nonhydroxyl ated analogs of BIS-GMA, the

basic resin in conventional dental composites, resulted in a composite

with adequate physical properties but did not enable us to reduce water

sorption significantly.

Since we hypothesize that to significantly lower both microleakage

and water sorption we need a resin system that is hydrophobic and that

on curing shrinks minimally, we have begun examination of composite

formulations derived with the very large experimental prepolymer, PFMA,

a highly fluorinated polymeric (approximately 10 repeating units) comonomer

with multiple methacrylate groups for chain extension and cross-linking.

To achieve workable viscosities we are diluting with highly hydrophobic

563-31
comonomers such as 1,10-decamethylene dimethacrylate or neopentyl glycol

dimethacrylate. Results to date indicate promise in terms of reduced

water sorption and microleakage and respectable physical properties.

Porcelain Fused To Base Metal Alloys and Dental Ceramics

Subtask 5 of Task 12135

J. A. Tesk, R. W. Hinman 1

, W. deRijk2, D. L. Menis 2

, G. Widera3 J. Sanecki 4

, 0. Franklin 5

, and J. Arnold6

Research Associate, U. S. Navy

2 Research Associate, American Dental Association

3 University of Illinois

4 Visitor, Howmedica, Inc.

5 Visitor, Dentsply International

6 Visitor, Williams Gold

A major cause of failure in porcelain-fused-to-metal restorations involves

cracking or delaminating of the porcelain veneer. Apropos to this

situation we developed a new concept for evaluation of porcelain-to-metal

bond strength. The test uses four-point bending of a metal strip to

which porcelain squares have been fused and measures tensile strengths

of porcelain-to-metal bonds (without influence from shear stresses).

Recent finite element model (FEM) calculations confirm that simple beam

theory provides an adequate description of the stress within the system.

The effective stress is virtually the same as the normal tensile stress

( i . e . , other stresses, such as shear stresses are small) and both are essentially the same (to within about 6 percent on the average) as stresses calculated by beam theory. Moreover, a smooth transition of

stress from metal through porcelain is indicated by FEM calculations

which were conducted using an elastic modulus for metal, Em

, twice that

for porcelain, E , i.e., E /E =2.

p m p

Preliminary test results have shown that two to four strength determinations can be made from one test specimen. Application of St. Venant's

principle resulted in specimen test design intended to leave such successive strength determination independent of previous fractures. What is

determined is either the porcelain-to-metal bond strength or the porcelain

fracture strength. Test results show that for strong porcelain-to-metal

bonds only porcelain fractures are recorded. For weak bonds at interfaces

only interface fractures are recorded. In other cases, mixed failures

occur, i.e., a porcelain-to-metal bond failure may be preceded by a porcelain fracture and followed by two more porcelain fractures; other

possibilities are obvious. Because the order of failures (fractures) is

expected to be toward continuously increasing strength values, statistical interpretation in terms of ordered statistics will be investigated.

Experiments are currently in progress to develop meaningful statistical

data as the preliminary testing has been essentially completed.

Industry has expressed great interest in the new test methodology as it

offers the potential of producing quantitative as well as qualitative

information on porcelain-to-metal bonding and on relatively easily

prepared specimens which yield several pieces of information per test

563-32
run. Three dental companies committed R&D personnel to work as visitors

for one week in an evaluation of the test methodology.

We have previously developed rationale for utilizing the change in gap

of a porcelain veneered split metal ring as a measure of porcelain/alloy

stress compatibility. Recent work has centered on development of the

FEM which incorporates the viscoelastic properties of porcelain. Difficulties have been experienced with the continuity of the computer program

and these are currently being worked on. This, coupled with a recent

concentration of effort on the porcelain-fused-to-metal bond, testing

and castability evaluations has resulted in delaying progress. This

work is expected to renew in intensity as we are joined by guest workers

from Germany and Japan.

The thermal expansion behavior of many experimental porcelain compositions

have been determined. These porcelains have been formulated to achieve

very low fusing temperatures, i.e., below 800 °C. The coefficient of

thermal expansion usually varies with temperature and, in general, the

relationships can be grouped into three different classes: (1) a monotonic

increase with temperature; (2) an irregular change with temperature; and

(3) no change with temperature. These findings demonstrate that matching

the coefficients of thermal expansion of metal and porcelain at only one high temperature as is usually done may not lead to an optimal porcelainto-metal system.

Mathematical analysis has been performed on the data obtained in studies

of the effects of various ingredients that influence the fusion temperature in experimental porcelains. It was found that a wide range of B 2 0 3

concentrations has a surprisingly small effect on the fusion temperature

of these experimental porcelains.

During the past year new investments for use with titanium metal have

been investigated. The preliminary studies showed that Si02 , A1 2 03 and

A1P04 are ingredients to be avoided. Molten titanium acts as an extremely

strong reducing agent and reduces Si02 while forming a titanium oxide.

It was found that similar reactions occur with aluminum oxide and aluminum

phosphate. Three oxides that are relatively stable have been identified,

namely those of magnesium, yttrium and zirconium. However, moldcoats of

these oxides, used as liners with conventional phosphate-bonded investments, were unsuccessful because of poor adherence to the investment.

\

Dental Casting Alloys and Investments

Subtask 6 of Task 12135

J. A. Tesk, R. M. Waterstrat1

, R. W. Hinman2

, W. deRijk1

, and D. L. Menis 1

Research Associate, American Dental Association

2 Research Associate, U. S. Navy

Dental casting alloys based on gold or cobale have, in recent years,

faced serious problems of cost and availability. Though these problems

have eased somewhat, they could recur at any time. The use of nickel

alloys as substitutes has faced some concern for their toxicity and

induced allergic responses in certain patients. Titanium-based alloys

563-33
would seem to offer a satisfactory alternative, being strong, corrosionresistant, relatively inexpensive, widely available, and nontoxic. A

study of the effects of interstitial solutes (0, N, C) on phase equilibria

in Ti-rich Ti-Al alloys was initiated. Also, high- temperature neutron

diffraction experiments are planned in collaboration with the NBS reactor

group. Equipment designed to permit observations of alloys to 1200 °C

is under construction.

With the introduction of numerous dental alloys as alternatives to gold

alloys, it becomes increasingly important to develop a castability test

that is indicative of an alloy's ability to fill a mold of specific

design under a set of prescribed conditions. Such a test has been under

development in this laboratory and in its present stage assesses the

percentage, C

v

, of cast segments of a polyester grid pattern, figure 1. We have applied the test to a number of dental alloys using the manu- facturer's recommended mold and alloy casting temperatures. Results of

C

v determinations are shown for several dental alloys as they are cast

using different investments, figure 2.

The following observations support the validity of applying the test

method: (1) some of the presently employed alternative alloys compare

favorably in castability to those of high noble content; (2) the brand

of mold investment used can produce a significant effect on the castability

of some alloys; (3) as expected, the castability value increases as mold

and casting temperatures increase; (4) an optimal mold and casting

temperature can be discerned for each alloy beyond which castability

values show little change; (5) for each alloy a different amount of heat

above liquidus ("superheat") is required to produce the optimal casting

temperature; (6) the effect of mold temperature on castability may be

greater than previously thought for some alloys and less significant for

others; and (7) as the limiting value for castability is approached

(C

v = 100 percent) the standard deviation (SD) from the mean determination

of C

v appears to decrease. Hence, larger SDs for some alloys may well

be indicative of potential for further optimization of conditions for

casting of that alloy.

As can be seen from the foregoing observations, the investment, the

temperatures used, and probably many other factors have to be taken into

account when comparing the castability of dental alloys. As a further

example of this, preliminary studies using torch casting indicate that

the castability value for some alloys is altered significantly from

those cast by induction melting. A question that naturally arises is:

what threshold castability value is acceptable? This again brings up

the point previously made, that the test method should be used where

relative comparisons are desired and that the significance of the absolute

castability value of any alloy system by itself is an unanswered question

and is at present a matter of conjecture.

It is apparent from the data that the standard deviation of the castability

value, SD

Cv , is a function of C v> the casting temperature, T

c

, and mold

temperature, Tm, i.e., SD^ = f(Cw , T„, Tm). The form of the relationship

v* c’

563-34
has not yet been determined (standard statistical transformations have

been found not to apply and are the subject of continuing work). We

only wish to note at this point that if a universally applicable relationship can be found it will significantly reduce the number of experiments

required to completely determine castability for any alloy as a function

of temperature. The benefits of such a relationship should be obvious

to those engaged in quality control, product development or setting of

standards.

A final point should be made on the repeatability of the results as reported here. One base metal alloy having a castability value toward

the center of the range was cast on five separate occasions to monitor

this aspect. The results were statistically indistinguishable.

Dental Chemistry and Preventive Dental Treatments

Subtask 7 of Task 12135

W. E. Brown 1

, L. C. Chow1, M. Mathew1, M. S. Tung 1

, G. L. Vogel 1

, S. Takagi 1

, T. M. Gregory 1, and A. Uchida2

Research Associate, American Dental Association

2 Guest Worker, Tokushima University, Japan

The objective of this project is to develop and apply fundamental information on the solubilities and crystallographic structures of biologically

important calcium-containing phosphate compounds to the development of

improved dental caries preventive techniques. Important portions of

this effort are concerned with (1) development of physico-chemical

models of the caries process to include insight into the mechanisms by

which impurities and defects are incorporated onto tooth enamel, and (2)

application of solubility phase diagram analysis and kinetic data to the

development of more effective enamel acid-etch bonding treatments and

improved topical fluoride procedures.

During the past year, the crystal structures of CaK3 H(P04 ) 2 and

Ca(NH4 )P0 4 *7H2 0 were determined. Structure analysis of a calcium phosphateurea complex, predicted to possess a layer- type structure, has revealed

it to be a non-layer type compound. A structural study of natural and

synthetic crystals of bobierrite, Mg3 (P04 ) 2 *2H2 0 revealed the positions

of the hydrogen ions in this member of an important and varied class of

compounds. Research on the structure of octacalcium phosphate,

Ca8 H2 (P04 ) 6 *5H2 0, and its role in biomineralization continues to be a major activity. During the report period, the refinement of the crystal

structure was completed; important evidence for its participation in the

formation of enamel mineral was gained. A chemical procedure was developed

that for the first time makes it possible to measure separately the rate

of its formation and rate of its conversion to the basic mineral of bone

and tooth.

The work on caries mechanisms is carried out on three levels: (1) theoretical considerations to develop physicochemical principles which might

govern the caries process; (2) bench-scale experiments to validate such

principles; and (3) ultramicro studies on tooth sections to establish on

a quantitative basis the events occurring within the tooth itself.

563-35
Theoretical considerations focus on the idea, heretofore largely ignored,

that the relative rates of diffusion of ions into and out of the lesion

are important parameters in the caries process. It was predicted and

subsequently confirmed that factors such as the presence of fluoride,

the membrane-like behavior of the outer surface of the tooth and the

plaque, and neutral salts normally present in the saliva are among the

important parameters affecting the rate of the caries process. Bench-scale

studies showed that the rate of demineralization was increased by a factor

of 80 when the membrane transmitted positive ions selectively as compared

to when it transmitted negative ions selectively. Also, F“ greatly

reduced the rate of demineralization (this effect appeared to be greatest

at pHs below about four). These results provide further evidence in

support of a cariostatic mechanism for F~ developed at NBS and suggest

that the caries resistance of teeth may be increased by modifying the

selectivity of the tooth surface to transmission of ions. In ultramicro

studies, good progress was made in developing pieces of equipment and

procedures for working in the nanoliter (10~9 liter) sample range. The

techniques have been extended to include analysis of plaque samples

where the volumes of plaque are sufficiently small so that they can be

collected from a single tooth.

In addition to the studies on the role of fluoride in the caries mechanism,

work continues on the new topical fluoridation procedures developed in

these laboratories. These procedures are based on the idea that tooth

mineral (primarily Ca 5 (P04 ) 3 0H) reacts very slowly with F“. However, as

a part of the fluoridation treatment, some of the Ca 5 (P0 4 ) 30 H can be

converted to another compound, CaHP04 *2H2 0, which reacts rapidly with

F“. Through the use of procedures based on this principle, it has been

found possible to greatly increase the permanently-held F~ content of

teeth. The clinical relevance of this increased F~ content remains to

be established, but it is plausible that it should be beneficial.

A successful remineralization procedure would drastically alter the

procedures used to treat incipient lesions. During this period, initial

steps were taken to develop procedures for testing remineralization

formulations based on prior basic studies carried out in these laboratories. The initial results are encouraging. Substantial progress was made in developing techniques to remineralize exposed and sensitive root

surfaces. A procedure was developed which by laboratory criteria appears

to be a successful remineralization procedure. It is expected that preliminary clinical evaluations will be carried out in the near future.

Clinical & Laboratory Investigation of Dental Amalgams, Composites &

Cements

Subtask 8 of Task 12135

N. W. Rupp 1

, G. C. Paffenbarger 1, and R. M. Waterstrat 1

Research Associate, American Dental Association

Dental restorations vary considerably with time. Among the factors

influencing the success or failure are: (1) the material and how it was handled by the operator; (2) the cavity preparation; and (3) the patient's

563-36
home care. Sorting out the factors contributing to the durability of a restoration requires a careful combination of clinical studies and

laboratory analyses.

Observations of amalgam restorations placed 7 to 8 years ago are continuing

in the clinic and laboratory. Amalgams that are high in copper content

and are highly creep-resistant continue to be superior. The relation

between marginal integrity and creep, if the creep is below 2 percent, is more dependent on operator manipulation than on creep; for example, creep

values of 0.2 or 0.8 percent do not seem to correlate with the quality of

the margins. Alloy composition and the resultant amalgam composition influence the aging characteristics. Laboratory measurements of dimentional

change have been made for six years on specimens stored at 23, 37, and

60 °C on either unrestricted specimens or in specimens restricted by

placement in simulated Class V Cavities in steel blocks. Zinc, tin, and

mercury contents, each independently, affect the dimensional changes:

increasing the zinc and mercury contents seems to cause an expansion,

while tin over 28 percent usually results in shrinkage. There are, however, some exceptions. As we gain a better understanding of the rheology

and the internal phase changes, it should be possible to extend the useful

life of amalgam restorations.

One of the principal defects in composite restorations continues to

be imperfect sealing of gingival margins. Laboratory studies confirmed

that microstructural bonding of composites to enamel successfully prevents

microleakage, and that the paucity of enamel at the gingival margin

obviates sealing through the use of acid-etch bonding. Currently the

only commercially available materials that are adhesive to dentin are those with carboxyl groups. Clinical observations were made with glass

ionomer cements which contain these groups, and the adhesion does appear

to be good; the visual opacity of these materials continues to be a problem.

There is also an available product that utilizes a coupling agent

that is polymeric and contains carboxyl groups. This system does not

call for treatment of the dentin with citric acid (which opens the

tubules to irritants). I_n vitro and i_n vivo testing of this coupling

agent-composite system is being pursued to assure that this combination

can be advocated for general use. If so, this will reduce staining and

decay at the gingival margins of composite restorations.

Adhesion of Synthetic Polymers on Solid Surfaces

Subtask 9 of Task 12135

R. E. Dehl and W. H. Grant

The adhesion of polymeric protective coatings, with its many important

commercial applications, is hampered by a lack of fundamental understanding

of the interaction of polymer molecules with solid surfaces. It is the

energy of adsorption of individual polymers with a surface which determines

the adhesive strength of an adhering polymer film, and there is a need

for more specific information about such factors as the role of individual

polymer segments attached in governing the adhesive strength. One

measure of the energy of attachment is the rate at which polymers desorb

563-37
from solid substrates when the coated surface is placed in contact with

a suitable solvent. The results of previous NBS studies, using radiolabeled

polystyrene to detect the amount of polymer remaining on the surface,

indicate that the rate of desorption decreases with increasing molecular

weight of the polymer and with the amount of polymer initially adsorbed.

We have also previously reported that the rate of desorption of tritiumlabeled polystyrene from solid surfaces depends not only upon the amount

adsorbed, but also upon the way in which a given level of adsorbance is

achieved. Such factors as the time of adsorption, which can be controlled

by adjusting solution concentration, and preadsorption to higher adsorbance

levels were found to affect the desorption rate from the same adsorbance

level. A model was proposed to explain these phenomena, based upon two

or more types of adsorption sites having different energies of attraction

for polymer molecules.

During the past year, we have found that the rate of adsorption and

desorption studied over long periods of time may be complicated by the

tendency of high molecular weight (MW) species to degrade in time. One

polystyrene solution which had been used for several months was found by

gel permeation chromatography (GPC) to have a broader MW distribution

and a lower average MW than a fresh solution of the polymer. Whether

this degradation is due to chemical attack or the shearing action of the

reciprocating stirrer bath used in these studies is not known at present.

However, it has also been found that the GPC elution curves of fresh

polymer solutions do not differ significantly from those obtained after

shaking the solutions for six weeks in the stirrer bath, indicating

minimal degradation over this time interval. Future studies will be

conducted within a six-week period in order to minimize the effects of

polymer degradation.

Characterization of Porosity of Porous Implant Materials

Subtask 10 of Task 12135

R. E. Dehl

Porous synthetic biomaterials are currently being used as implants,

where they become stabilized by the ingrowth of hard or soft natural

tissues. Both the rate and the type of tissue ingrowth are affected by

the porosity of the materials, and it is important to be able to characterize

the porosity by reliable and reproducible methods. During the first

phase of this work, which is being carried out in cooperation with the

Bureau of Medical Devices, Food and Drug Administration, we have surveyed

the published literature pertaining to porous polymeric implant materials

and initiated studies of pore size and pore volume using mercury intrusion

porosimetry. The materials currently being investigated are porous

polyethylene (PPE) and a porous composite of polytetraf 1 uoroethyl ene and

pyrolitic carbon.

Our initial studies indicated qualitatively that, contrary to some expressed fears, mercury intrusion experiments apparently can be performed

on the relatively soft composite material without distorting the pore

structure by mechanical compression. During the past year we have quantified these observations by performing compressive stress-strain measurements on both materials. The composite has highly anisotropic mechanical

563-38
properties due to its laminated construction, the compression modulus

being about five times greater in the direction parallel to the laminations, as compared with perpendicular compression.

The pore volume in these materials has been measured by three different

methods and the pore "size" by two methods, namely mercury intrusion

porosimetry and an indirect method based upon the specific surface area

and specific pore volume. The surface areas have been measured both by

the Brunauer, Emmet, Teller (BET) inert gas adsorption method and by the

mercury porosimetry method in which the surface area is proportional to

the integrated area of a pressure- volume mercury intrusion curve. Both

methods agree that the PPE has a smaller surface area than the composite,

but the BET method indicates a much greater difference, for reasons which

are currently under investigation.

The accuracy of the mercury intrusion method for measuring pore size has

been tested by performing an estimated random error analysis of the

experiment and plotting volume-weighted pore size distribution curves based upon these error limits. The resulting curves show that the

experimental precision is not sufficient to produce well resolved

distribution curves, over much of the pressure range pertinent to these

materials, but that the precision increases rapidly with increasing

pressure, corresponding to smaller pores.

Quantitative studies of porosity are also being initiated, using the

methods of quantitative stereology. The accomplishment of this project's

objectives will be of significance to the medical device industry and

medical implant standards development, as well as to the users of porous

implant materials.

Surgical Bone Cement Modification

Subtask 11 of Task 12135

J. A. Tesk, G. M. Brauer, W. Wu, and J. E. McKinney

While surgical bone cement is a major asset in orthopaedic practice, it

has deficiencies that are of much concern, particularly in total joint

replacement. Failure at the cement/bone or cement/implant interface is

considered to be an important step in reducing the life time of such

total joint replacements as those used to reconstruct knee and hip joints.

With the view that completely new bone cements are not likely to be

forthcoming, we have directed our efforts to improving the presently

available materials and techniques. A first effort has been to examine

the potential of some less toxic new amines, proven in our lab to be more reactive with the dental resin, BIS-GMA, than amines currently

employed. We have found that dial kyl ami nophenethanol used with benzoyl

peroxide as initiator will give faster curing of bone cement. This cure

time is reduced even more by addition of equimolar concentrations of

benzoic acid. We have initiated efforts to reduce the heat liberated on polymerization by bone cement by investigating the substitution of the

reactive but higher molecular weight dicyclopentyloxyethyl methacrylate

for presently used methyl methacrylate.

563-39
Based on the results of the amine studies additional tests will be

chosen from among those considered in the original protocol. One such avenue of investigation involves determining if performance may be

expected to be improved by precoating of a prosthetic stem with highly

cured polymer. The properties of the polymer are expected to be improved

relative to properties at the interface of a stem and self-curing acrylic;

the stem will be a heat sink and the lower interface temperature should

inhibit obtaining an optimum cure. A precoated stem, however, will be

insulated from the self-curing acrylic, the polymer itself should be

solvated somewhat by the self curing monomer, and interface properties

improved by the post curing of the precoat.

At present, 10 cobalt-chromium rods 3/8" diameter have been cast (courtesy,

Howmedica, Inc.) and prepared for testing with polymer. Initial tests are

in progress regarding comparative pushout force-displacement evaluation

of coated and uncoated rods.

Dental and Medical Materials Standards

Subtask 12 of Task 12135

J. M. Cassel , J. A. Tesk, G. M. Brauer, and N. W. Rupp 1

Research Associate, American Dental Association

Dental and medical implant standards development is strongly supported

by persons in positions of Committee, Subcommittee, and Task Force Chair

roles in ANSI MD 156, Dental Materials, Instruments, and Equipment, and

in ASTM F-4, Medical and Surgical Materials and Devices. Additional

leadership roles are fulfilled through the Chairpersons role in USA TAG

ISO/TC 150, Implants for Surgery, and USA TAG IS0/TC106, Dental Materials,

Instruments, and Equipment, and through participation in the Executive

Committee of the ANSI Medical Device, Standards Management Board.

Considerable effort has gone into drafting four new or revised ANSI/ADA

dental specifications and comparable ISO standards. These cover alloys,

mercury and devices used in the preparation of amalgams.

An active role was taken in the planning for and organization of U. S. participation in the Fifth Meeting of ISO/TC 150, Implants for Surgery,

held in Washington, DC.

563-40
38mm

Figure 1 Grid pattern.

563-41
CASTABILITY

USING STANDARD EVALUATION PROCEDURE

WITH DIFFERENT INVESTMENTS

Alloy N

Investment

A

B

C

D

E

Alloy P

Investment

Alloy U

Investment

A

B

C

D

E

Figure 2

563-42
MECHANICAL DURABILITY OF POLYMERS

Task 12136

The growth in the use of polymeric materials derives from substitution

for other materials as well as new applications due to the unique properties of these materials. In many applications long-term mechanical

durability is critically important. The realization of increased utilization is often limited by the lack of data and models upon which to

design for long-term use. Thus, the lack of adequate test methods and

data for evaluation of long-term mechanical performance not only restricts

applications, but also leads to over design which results in more expensive

items and limits weight savings. Evaluation and control of material

parameters that affect long-term performance should lead to more durable

materials and, hence, reliable performance for the intended service

life.

The objective of this task is to provide data, test methods, and standards

for evaluation of long-term mechanical durability of polymeric materials.

The approach is to identify and analyze principal failure mechanisms of

commercially important thermoplastics under mechanical stress in the use environment, to determine the effects of chemical structure and fine

structure morphology on mechanical properties and failure processes, and

to develop constitutive relationships and models for mechanical properties

to serve as the basis for accelerated test methodology and lifetime

prediction.

The approach to development and verification of predictive models of

mechanical performance are: (1) establish dependence of the principal

failure modes of inhomogeneous deformation and crack initiation and

growth on static and dynamic mechanical stress; (2) identify the principal

molecular processes associated with deformation and failure and relate

failure to molecular structure and fine texture; (3) evaluate the kinetic

theory of bond rupture as a model for degradation of mechanical properties

and for extrapolation of short-time measurements to predict long-time

performance; (4) on the basis of (1), model failure by neck formation and

propagation using time-dependent constitutive relations that predict the

onset of inhomogeneous deformation from baseline mechanical properties

characterization; and (5) expand fracture mechanics approach to viscoelastic materials to model craze and crack growth phenomena.

The National Bureau of Standards has established joint programs on mechanical durability with other Federal agencies which are fostering

the application of polymeric materials in areas of national concern.

For example, joint program with the Defense Advanced Research Projects

Agency is concerned with development of molecular characterization

techniques for mechanical degradation as the basis for nondestructive

evaluation methods. Joint projects are also executed with industries.

An example is the joint project with Firestone Tire and Rubber Company

on the effects of processing on PET structure and properties.

563-43
Molecular Processes Associated with Mechanical Deformation and Failure

Subtask 1 of Task 12136

B. M. Fanconi , D. L. VanderHart, S. J. Kryder, E. E. Toth, and

K. L. DeVries 1

1 College of Engineering, University of Utah

The elucidation of molecular processes and structure changes accompanying

mechanical deformation and failure not only provides the basis for

development of test methods for long-term performance and quality control,

but also provides insight into the selection and design of materials

with improved mechanical performance and durability. The semi crystal 1 ine

structures found in some commonly used polymeric materials present

significant challenges to characterization of molecular structure.

Newly developed spectroscopic techniques involving 13 C nuclear magnetic

resonance (NMR) and FTIR spectroscopies are used to elucidate molecular

conformations in disordered material. Reorganization of polymer molecules

during deformation affects mechanical performance. Identification of

the molecular processes involved and the physical structures which

result are the aim of the studies.

FTIR is used to determine relationships between the number of chain

scissions produced by mechanical stress, the useful service life, and

molecular weight and its distribution.

Chain Scission and Mechanical Durability of Polymers

Chain scission is an underlying molecular process associated with mechanical deformation and degradation. Previous work has established that

infrared spectroscopy can be used to determine the number of carbon-carbon

bonds that are ruptured under mechanical stress to form new chemical end

groups.

We had applied this method to determine the number of chain scissions at

fracture per measured free radical, the precursor to new end group

formation. Our measurements, utilizing the improved signal-to-noise

capability of Fourier transform infrared spectroscopy, established that

the number of chain scissions per free radical was 1 to 2 orders of

magnitude lower than previous estimates.

Spectral studies of chain scission have now been extended to ultra high

molecular weight polyethylene damaged under fatigue loading, and to

polystyrene damaged by fracturing at cryogenic temperatures. The latter

study was carried out as a function of molecular weight and correlations

with the electron spin resonance determinations of secondary free radical

concentrations have been made.

Specimens of ultra high molecular weight polyethylene (UHMWPE) were fatigued under uniaxial deformation at various frequencies and peak

stresses. The applied load varied sinusoidally in time. The fatigued

specimens were examined using FTIR after failure occurred. In table 1

is shown the concentrations of carbonyl end groups found in specimens of

UHMWPE fatigued at 0.002 Hz and in which the peak stress varied from 30 to

563-44
Table 1

Peak Stress (MPa) Concentration of C=0

(number per gram)

30 1.95 x 10 18

35 1.82 x 10 18

40 2.03 x 10 18

45 1.97 x 10 18

45 MPa. The carbonyl and methyl groups were the only ones that showed

an increased concentration as a result of mechanical damage. The vinyl

bonds did not show any measurable change, even though the initial concen- trations of these groups were extremely low which would facilitate the

observation of small changes in concentration. This finding substantiates

our earlier conclusions that the previously reported changes in vinyl

group concentrations resulted from poor sampling procedures and the

initially high concentrations of vinyl groups. We also observed increases

in methyl group concentrations but do not report these because of the

large uncertainties that result from the strong IR absorption due to

methylene wagging modes in the same frequency range.

The significant result from table 1 is that the concentration of new end

groups at failure is independent of the number of cycles, peak stress

level, or time-to-failure. By varying peak stress the time-to-fai 1 ure and number of cycles to failure varied by two orders of magnitude. Our

findings suggest that failure is associated with a critical concentration

of bond ruptures and that IR measurements may serve as the basis for

nondestructive test methods. Current work is aimed at substantiating

the findings for different test frequencies and molecular weights.

Chain scission in a glassy polymer was examined using polystyrenes in

the molecular weight range of 200,000 to 800,000 g/mol . Specimens were

fractured by grinding at cryogenic temperatures and secondary free radical

concentrations measured by electron spin resonance prior to warming the

specimens to room temperature. The samples for infrared investigations

were prepared by melt or solvent casting films of the fractured and refer- ence material. Spectra were compared to those of the reference polymer

and the increased absorption due to new end groups was converted to concentrations using literature values of the extinction coefficient. The

viscosity- averaged molecular weight was also determined, and from assumptions of random chain scission the molecular weight changes were converted

to number of chain scissions. In table 2 we compare the number of free

radicals, the number of chain scissions by viscosity measurements, and the

IR-determined number of bond scissions. For this glassy polymer the change

in molecular weight and the IR measurements yield similar values of the

number of chain scissions. The electron spin resonance (ESR) values are lower by a factor of 2 to 3 indicating that a secondary free radical may

produce more than one chain scission. The insensitivity of the number of

chain scissions to molecular weight can be related to grinding at low

temperature where large scale molecular motion is prohibited.

563-45
Table 2

MW x 10 3 Viscometry Ruptures

number per cm3 x 10 -16

ESR R’/cm3 x 10"16

IR Chain Scissions

number/cm3 x 10 -16

220 17.0 ± 3 4.5 ± 2 17 ± 3

637 11.0 ± 3 6.3 ± 2 22 ± 4

916 15.0 ± 4 5.0 ± 2 24 ± 4

Examination of Drawn PET Fibers by Solid State NMR

This work is a continuation of work begun in FY81 and is a joint effort

with the Firestone Tire and Rubber Company. The interest is to learn

how to control shrinkage of PET fibers in tires during rubber curing

while maintaining mechanical strength.

In previous 13 C NMR studies on these materials, it became clear that a better understanding of the relationship between morphology and orientation in drawn PET fibers would be very helpful. Using the 13 C NMR

method, one could get a reasonable description of overall fiber orientation.

However, temperature-dependent studies showed significant heterogeneity

of molecular mobility among the oriented aromatic groups in a drawn

sample. This underscored the importance of understanding the nature of

the distinction between crystalline and noncrystalline phases in these

materials. Several NMR techniques were applied to this question making

use of magic angle sample spinning spectra, relaxation time measurements,

orientational measurements, and spin diffusion measurements. Although

x-ray techniques indicate rather small crystallite sizes, particularly

along the C-axis (3.5 to 6 nm), calculations of crystallinity from the

x-ray data contain a great deal of uncertainty.

In FY82 a different NMR approach to the question of crystallinity was

undertaken. This approach was based on the phenomenon of spin diffusion

(really diffusion of spin polarization). If a well-defined spin polarization gradient can be produced in a 2-phase system such as PET, and if

the system can be observed for a sufficiently long time thereafter (but a time short compared to the longitudinal relaxation time, T x ), the rate at

which spin polarization equilibrium is attained will indicate the size of

the domain(s) since the spin diffusion constant is approximately known.

Protons (and not 13 C) exhibit strong spin-diffusion characteristics.

Therefore, much effort was put forth finding the optimal conditions for

generating magnetization gradients between the two phases of the drawn

PET fibers. This problem is not easy because very few chains, below T , y

in PET undergo significant motion on the NMR timescale of 10 -5

s; therefore,

it is difficult to create polarization gradients below T . Above, T , y y

this task is easier but the sample also changes irreversibly. Although

some compromises have to be made, current efforts make use of differences

in rotating frame relaxation times between the two phases in order to
establish a polarization gradient. Preliminary results suggest that

equilibration times between the two phases are not a very sensitive

function of post-annealing history.

In a quantitative way, this suggests that there is no significant reduction

in surface area between the two phases. Moreover, annealing is not

significantly changing the sum of the crystalline plus noncrystall ine

domain size in the direction of minimum thickness. The distances for

this sum deduced from the spin diffusion rates are in range of 10 to 15 nm. This is in accord with x-ray results. The picture of drawn, annealed

(at constant length) fibers is that annealing increases the regular

ordering in the drawn fibers but it does not result in substantial

thickening of the crystalline regions. Moreover, in annealing, only

those chains which were originally wel 1 -oriented in the draw direction

are involved in the perfecting of order by annealing. Orientation in

the noncrystall ine region remains pretty much independent of annealing

with a slight disordering at high annealing temperatures. This is

probably the reason that modulus tends to degrade at high annealing

temperatures even though crystalline orientation remains high.

It should be noted that Dr. V. Mochel from Firestone Tire and Rubber

Company spent a week at NBS working on the project in FY81 and that

Dr. K. W. Zilm from Utah Research Institute spent a month in FY82 working

on some of the PET proton experiments.

Characterization of Ultrahigh Modulus Materials

This work is aimed at developing techniques to characterize structural

features of ultrahigh modulus polymeric materials. This year a collaboration effort was initiated with Professor Ian M. Ward of the University

of Leeds in England. Professor Ward has extensive sample preparation

facilities for producing highly drawn materials. We are exploring the

possibilities that NMR may be able to obtain information about tie

molecules, those molecules that bridge one crystalline lamella to another,

which are regarded as essential components for achieving a high modulus.

Studies are underway investigating effects of molecular weight, draw

ratio, and draw temperature. One of the measures which may relate to

tie molecules is longitudinal growth of 13 C magnetization in the intermediate time regime. This magnetization has the appropriate orientation to

correspond to tie molecules. In preliminary investigations to date, the

number of chain segments corresponding to this magnetization is roughly

proportional to the noncrystalline fraction in all drawn materials. A

significant observation which lends credence to this pursuit is the

smaller fraction of material associated with this magnetization in an unoriented sample where we would expect fewer tie molecules traversing

the noncrystall ine region.

Investigations of Cellulosic Materials used in Paper Making

A cooperative effort with the Bureau of Engraving and Printing is aimed

at identifying more durable and less expensive substitutes for currency

papers which are presently made from linen and cotton cellulosic materials.

Wood pulps are a much more available source of materials but the mechanical

characteristics of these papers is generally inferior. A fundamental

563-47
question is how the morphology of paper affects its mechanical properties

and durability. In FY81 we used magic angle spinning (MAS) 13 C NMR to

investigate any modifications to the surface area of cotton and wood

pulp materials as a result of wet beating. (Wet beating is the process

whereby pulps are sufficiently plasticized in order to make paper.) One

of the characteristics of the 13 C spectra is that the presence of water

in various amounts produces only minor changes in the spectra. Therefore,

in an effort to understand the microstructure of cellulose better, an intensive effort was put forth to obtain more information about the

interaction between H 2 0 and cellulose. A significant objective in these

studies is to answer the question of whether disorder in native celluloses

is associated with only disorder on the surface of cellulose fibrils, or disorder also exists in three-dimensional noncrystalline regions. The

spin diffusion studies combined with 13 C-MAS experiments should shed

significant light on this question. To date, the principal material for

study has been cotton. The transfer of magnetization between water and

cellulose, via spin diffusion, has been witnessed as a function of water

content. It has been established by 13 C NMR that proton magnetization

gradients in the cellulose can indeed exist, thereby leaving open the

possibility that three-dimensional disordered regions exist.

The Distribution of Stresses in Crazes at Crack Tips

Subtask 2 of Task 12136

E. Passaglia

When computing any of several criteria for crack-growth (such as critical

crack opening displacement or work to fracture) in crazing polymers, it

is necessary to know the distribution of stresses within the craze. From this distribution the craze displacement profile may be calculated,

giving crack opening displacement directly, or work to fracture by the

product of stress and displacement.

Many workers have used the Dugdale model for the craze which assumes a constant stress within the craze. On the other hand, by direct determination from the electron microscopic observation of the displacement

profile in either continuous crazes or crazes at crack tips, Kramer and

co-workers [1,2] have shown that the stress is not constant within the

craze. Most typically, it has a peak at the craze tip, and may also rise

at the crack tip.

It becomes of interest, therefore to develop a means for determining the

stress distribution in a craze. This may be done if the craze is modeled

as a necking and drawing process. It has been shown that this leads to

reasonable results [3]. In this model, in a moving crack, material at

the craze tip is assumed to fibrillate, with the fibrils drawing out

from the unf ibri 1 1 ated substrate, as the necked polymer is drawn from

the unnecked in a drawing process. The rate of craze displacement thus

corresponds to the rate of drawing, and the stress will be a function of

this rate.

Consider now a crack with a craze zone at its tip propagating uniformly

under the action of an applied stress intensity factor K. If under this

condition of uniform translation the craze stress cancels the stress

563-48
singularity that would otherwise be present, the displacement may easily

be calculated [4]. (It is noted that this implies a critical crack

opening displacement or work to fracture criterion for crack advance.)

Now denoting the displacement by w, and the crack velocity by v, from

the condition of uniform translation we have

(8w/8t)

x = -v (8w/3X)

t (1)

where X is a position coordinate. With an origin at the crack tip and

coordinate |,

8w/8t

x = v 8w/8i . (2)

From the displacement, 8w/8| is easily evaluated. This gives

aw/34 = Ce/2n J o(4)(4/4) 1/2 <£/£-£ , (3)

0

where Ce is the plane strain compliance of the uncrazed material, a is

the craze length, cr(£) is the stress distribution in the craze, and £ is an integration variable. Now, since the stress is assumed to be a function of the rate of change of displacement at the point | we have

using Eqs. (2) and (3) a form of integral equation for the stress

distribution. A solution algorithm is the following:

(1) Assume a relation between stress and rate of change of displacement.

From the hypothesis that crazing may be modelled as necking, this

relation may be obtained for curves of yield and drawing stress as functions of the rate of drawing.

(2) Assume a stress distribution and calculate 8w/8| from Eq. (3).

(3) From Eq. (2), and the assumed relation between stress and rate of

draw, calculate ct(|). This should be the same as the assumed

stress distribution in (2).

Several attempts have been made at such a solution with these preliminary

and tentative results.

(1) A uniform stress distribution does not work, which is not surprising.

(2) A stress distribution, which has a peak at the craze tip, is constant

over most of the craze, and drops to zero at the crack tip, gives a rough approximate solution to the problem. Work on this problem

will continue.

[1] Lauterwasser , B. D. ; Kramer, E. J. Phil. Mag. A39: 469; 1979.

[2] Wang, W. V. ; Kramer, E. J. J. Mater. Sci.; in press.

[3] Verheulpen-Heymans , N. Polymer 21: 97; 1980.

[4] Schapery, R. A. Int. J. Fract. 11: 141; 1975.

563-49

A
A New Test Method for Environmental Stress-Crack Resistance

Subtask 3 of Task 12136

J. M. Crissman and L. J. Zapas

We reported previously (Polymer Science and Standards Division 1981

Annual Report) that over the past several years there has been renewed

interest in the development of a new test method for determining the

environmental stress-crack resistance (ESCR) of ethylene based plastics.

As part of our studies concerned with long time behavior, durability,

and fracture of polyethyl enes , we have examined a number of possible

test methods which yield information concerning ESCR. One of these

methods we propose as a viable alternative to either of the test methods

currently recommended by ASTM for determining ESCR. The proposed new test method has advantages over existing methods. (1) The specimens

are maintained in a fixed and constant geometry. (2) The testing time

is reduced. (3) The experimental scatter in the data is reduced.

The proposed new test combined features of the two most widely accepted

test methods for ESCR, ASTM D-1693 and ASTM D-2552. The specimen is

bent around a metallic form having a fixed radius of curvature. At the same time it is subjected to a constant applied load at an elevated

temperature. During the past two years work has proceeded to determine

an optimum set of test conditions for polyethylenes having widely different

molecular weights. Test variables being considered are the specimen

thickness, bend radius, applied load, and temperature. Four different

polyethylenes ranging in molecular weight from 10 5 to 4 x 10 6 have been

used in this work. Based upon the test results for more than 400 specimens

the following set of test conditions was chosen.

A description of the test method, as well as a summary of the test

results, including the appropriate statistical data, was presented

before Committee D-20.12.03 of ASTM at their June 1982 meeting in Toronto,

Canada. Subcommittee D-20.12.03 is currently in the initial stages of

forming a task group to consider carrying out a round-robin test using

the proposed new test method.

Creep and Recovery of UHMWPE at Very Small Deformations: A New One - Dimensional Constitutive Equation

Subtask 4 of Task 12136

L. J. Zapas and J. M. Crissman

Since the early work on the mechanical properties of natural polymeric

materials well over one hundred years ago [1,2] it was found that reproducible data could be obtained only after the specimens had been mechanically preconditioned. Leaderman in his classical publication on the

"...Properties of Filamentous Materials. .. "[3] reported that even for

synthetic polymers the Boltzmann superposition could be obtained only

Specimen Thickness

Bend Radius

Applied Stress

Temperature

0.100 to 0. 125 cm 0.55 cm

5 MPa

60 to 75 °C

563-50
when the materials were subjected to mechanical preconditioning. The

necessity of preconditioning the material raises questions as to what

one measures as material properties of the virgin or unconditioned

polymer. Another difficulty has been the inability of the BZK Theory

[4] to describe quantitatively the two-step stress-relaxation experiments

where the second step is smaller or equal to one half the value of the

first step.

To better understand this behavior we have obtained data on unconditioned

specimens of an ultra high molecular weight polyethylene (UHMWPE) which

were subjected to a variety of different strain histories in uniaxial

extension. The observed behavior led us to a one dimensional constitutive

relation which describes very well all of our experimental results. In

the new derivation, the assumption is that the undistorted state of the

material depends upon the stress history. This means that the strain

which the material itself sees is not that which the observer sees. For

very small deformations, of the order of one percent and below, the

constitutive relation is given by the following equation:

t t

e(t) - (/ g(o(|))d£) = J(o(t),0) + J J*(o(|) ,t-£)d£, (1)

-00 -00

where e(t) is the strain the observer sees, a(t) is applied true stress,

<K.) is a functional, and J(a,t) is a nonlinear compliance. J*(.,.)

denotes the partial derivative of J(.,.) with respect to the second

argument. When <{>(•) is zero and J(a,t) is linear in a, equation (1)

reduces to the Boltzmann equation. The functionals 0 and J can be

obtained from a series of creep and recovery experiments.

We have carried out such a series of experiments on the UHMWPE and it is

found that the functions (j) and J can be represented rather well by the

expressions

<KJ g(a(£))d|) = (J g(a(4))d|) 1/3

, 0 0

( 2 )

and

J(a,t) = f x (ct) + f 2 (a) t

1/,J

(3)

Relations (2) and (3) along with equation (1) give interesting prediction

that recovery data, obtained from a series of creep experiments done at

constant stress but different values of the duration of the step, can be

superposed onto a master curve with predetermined shift factors along

both the strain and time axes. This was done and the data points on the

resultant master curve formed a very narrow band of the order of 10 percent

or less, which is as good as the reproducibility of the creep curves

from specimen to specimen. We have also calculated the behavior for

multi step creep and recovery experiments and the agreement was within

2 percent of the experimental values.

Since Eq. (1) is nonlinear, it cannot be inverted in order to determine

the stress as a function of the strain history. However, the consistency

of Eq. (1) can be determined from experiments where the stress is measured

563-51
as a function of the strain history, by assuming that, infinitesimally

in time, the motions are obtained from constant stress experiments.

This was done for single- and two-step stress-relaxation experiments and

the predicted strains were within a few percent of the actual applied

strains. For a two step in strain experiment, where the second step was very close to half the strain of the first step, the BZK prediction gave

results for the second step which were higher by 45 percent, while the

strains calculated using Eq. (1) fell within 3 percent of the experimental

values. The proposed viscoelastic equation appears to have the necessary

elements in order to be capable of describing quantitatively both the

creep and recovery behavior of a wide range of materials.

[1] Weber, W. Ueber die elasticitat der seidenfaden. Pogg. Ann. Physik

4: 247; 1835.

[2] Weber, W. Ueber die elasticitat fester Korper. Pogg. Ann. Physik

24: 1; 1841.

[3] Leaderman, H. Elastic and creep properties of filamentous materials

and other high polymers. The Textile Foundation, Washington, DC;

1943.

[4] Bernstein, B. ; Kearsley, E. A.; Zapas, L. J. Trans. Soc. Rheol. 7: 391; 1963.

A Study of the Morphology and Mechanical Properties, and Their Dependence

on Thermal History and Processing of Ultra High Molecular Weight Polyethylene

Subtask 5 of Task 12136

J. M. Crissman and F. Khoury

Ultra high molecular weight polyethylene (UHMWPE) is used in the manufacture of a variety of orthopedic joint prostheses. One factor which

limits the lifetime of a prosthesis is the durability of the UHMWPE

component. The length of time between device implantation and failure

depends upon time dependent processes which result from the clinical

loading environment. In clinical use, failure of the polymeric

component has been reported to occur as a result of creep, wear, fatigue

associated with wear, and even fracture. Both the mechanical properties

and durability are determined by the polymer chemistry and morphology

related features. Factors such as crystallinity, orientation, spherulite

size and texture, as well as molecular weight and molecular weight

distribtion all influence mechanical performance. Under contract with

the Bureau of Medical Devices, Food and Drug Administration, we are in

the third year of a study concerned with the relationship between the

morphology of UHMWPE and the mechanical behavior. An important aspect

of this work is the determination of the mechanical behavior variability

which can be brought about by changes in processing conditions.

A summary of the earlier work done in this project is contained in the

Polymer Science and Standards Division 1981 Annual Report. The initial

stages of the work dealt mainly with (1) characterization of the raw polymer powder, (2) establishment of procedures for compression molding,

under vacuum, sheets and cylinders of the UHMWPE, (3) characterization of

563-52
the processed polymer, and (4) initiation of preliminary experiments on the creep, stress-relaxation, and fatigue behavior of UHMWPE. We have

previously reported on the morphology, density, and uniaxial stretching

and recovery of compression molded sheets made from a UHMWPE polymer (UH-1)

having an intrinsic viscosity of * 25 dl/g (MW ~ 4 x 106

). The sheets

were “molded at 200 °C and then cooled to room temperature at ^ 1 °C/min.

The density of these sheets was in the range 0.934 to 0.936 g/cm3

, the

higher density corresponding to a weight percent crystallinity, x, of

59.7 percent. Sheets which were quenched from the melt into cold water

have a density of 0.923 g/cm3 (x = 51.5 percent). In order to determine

whether appreciable higher crystallinities can be achieved with this

polymer, sheets of the slowly cooled material were annealed in nitrogen

at successively higher temperatures in the range 125 to 135 °C. The

highest density attained was 0.942 g/cm3

(x = 63.4 percent).

Since molecular weight can also be an important factor in determining

mechanical behavior, in FY82 the work was expanded to include a lower

molecular weight UHMWPE (UH-2) having an intrinsic viscosity of ~ 18 dl/g

(MW ^ 2 x 106

). Sheets of the UH-2, prepared under the same three sets

of conditions described for the UH-1, had densities which ranged from

0.925 g/cm3 (x = 52.2 percent) for the quenched polymer to 0.953 (x = 70.7 percent) for the annealed polymer. Clearly, the crystallinities of

the molded sheets of the lower molecular weight polymer are not greatly

different than those of the UH-1 polymer.

The densities (crystallinities) of the compression molded sheets of both

polymers are comparable to those of commercial prostheses. The densities

of specimens cut from various regions of five acetabular cups and five

tibial plateaux were determined, and were found to fall in the range

0.923 to 0.953 g/cm3

, which spans the entire range found for the compression molded UH-1 and UH-2. It should be borne in mind, however, that

the prostheses were subjected to sterilization by irradiation which may

have effected their densities.

In addition to measuring the density of the sheets of UH-2 molded at

200 °C and slowly cooled to room temperature, we observed the following

similarities with the sheets of UH-1. First, a memory of the granular

texture of the raw polymer is retained in the molded specimens. Second,

specimens stretched uniaxial ly at 23 and 37 °C did not exhibit necking,

and showed considerable recovery when released at strains below the

breaking strain. For example, specimens stretched at a strain of ^ 0.2/min

to strains of 2 and 3, and which were then released, had, after 24 hours

storage at room temperature, residual strains of 1.09 and 1.86, respectively. Wide-angle x-ray diffraction patterns of such specimens revealed

the presence of reflections associated with the monoclinic polymorphic

form of polyethylene in addition to the reflections associated with the

predominant orthorhombic form. The particular aspect of the deformation

of sheets of UH-1 and UH-2 which is currently being investigated is the

apparent preferential deformation of the specimens (during the early

stages of drawing) at boundaries which delineate the "interfaces" between

the "sintered grains" of raw polymer.

563-53
In the area of mechanical properties studies, work centered on the

characterization of the creep and stress-relaxation behavior of both the

UH-1 and UH-2 polymers as a function of thermal treatment. Particular

emphasis was placed on single and multi-step creep recovery experiments

at very small deformations in uniaxial extension. It was found that, even at levels of strain of 0.001 and below, the stress-strain behavior

is nonlinear and the recovery behavior cannot be described by the

Boltzmann Superposition Principle. To better understand the behavior of

the UHMWPE a series of creep recovery experiments was done on unconditioned)

specimens in which either the applied stress was maintained constant and

the duration of the creep step was varied, or the duration of the creep

step was held constant and the applied stress was varied. The observed

behavior led us to a new one dimensional constitutive relation which

describes very well all our experimental results and the details of

which are described elsewhere in this Annual Report.

Work was also continued to characterize the environmental stress-crack

resistance of the two UHMWPE polymers. It was found that in general the

slowly cooled UH-1 and UH-2 had a longer lifetime in the surface active

agent that did either the quenched or annealed UH-1 and UH-2. Moreover,

the ESCR of the UH-2 was better than that of the UH-1 under the same set

of test conditions.

The Effects of Mechanical Deformation on Glassy Polymers

Subtask 6 or Task 12136

G. B. McKenna and A. J. Kovacs (C.R.M.)

According to Struik [1], large deformations of aged polymer glasses can result in erasure of the prior aging. From his experimental results,

Struik concluded that large stresses (or deformations) enhance the

molecular mobility of the aged glass to the point that the mechanical

properties are similar to those of a freshly quenched glass. He hypothesized that the deaging of a glass should be accompanied by changes in

(free) volume of a magnitude appropriate to the enhanced mobility. We

refer to these as structural effects, and to date there has been no experimental confirmation of them.

Deformation of compressible solids by tension and compression results in

relatively large changes in volume (first order effects) [2]. On the

other hand, torsional deformations are predicted from finite elasticity

theories to result in much smaller volume changes (second order effects)

[3]. We refer to these as mechanical effects . Because the volume

changes expected in torsion are much smaller than those accompanying

tension or compression, this geometry is more suitable to studying the

effects of deformation on the structure of polymer glasses.

There are two major objectives for this project: the measurement of the

effect of torsion on (a) the volume of a glassy sample and (b) on its

molecular mobility. As for the second theme, it is of particular importance to determine if any variation of the molecular mobility is accom- panied by a dilation when deaging (destabilization) is provoked by a deformation greater than a critical value. In the case of a positive

response to this question, one must then determine the magnitude of the

dilation in subtracting out any mechanically induced volume changes due

563-54
to the torsion. If the response is negative, we will attempt to determine

the possible origin of the destabilization and the parameters which

control it.

In order to accomplish the objectives, we have spent the past year in

building and perfecting a torsional dilatometer (TD). With the help of

this instrument we will be able to determine the effects of torsion on the volume of polymer glasses (a) in the absence of any destabilization

(mechanical effect) and (b) when the deformation is accompanied by a simultaneous increase in molecular mobility (structural effect).

The apparatus has been conceived to be able to measure simultaneously,

the torque, the normal force and the variation of the volume of a sample

subjected to torsional deformations controlled with precision, while the

length of the sample is held constant. The dilatometer is filled under vacuum with mercury through a capillary having a calibrated cross section.

This is illustrated schematically in figure 1.

An electric servo-motor is used to turn the sample (fig. 2). The motor

is commanded by a digital servo-system represented schematically in

figure 3. The system permits the performance of single- and multiplestep stress relaxation experiments at strains varying from y = 0.001 to

0.25 ± 8 x 10~5. The maximum time required to introduce the step is

less than 1 second. Constant rate of deformation experiments can also

be carried out.

The temperature of the dilatometer is maintained constant by circulation

from a water bath maintained to ± 1/500 °C. This precision is necessary

to give a sensitivity of the dilatometer to relative volume changes of

the order of ± 10"6. The accuracy on the torque is ^ ± 3.5 percent.

[1] Struik, L. C. E. Physical aging in amorphous polymers and other

materials. Elsevier Publishers, Amsterdam; 1978.

[2] Timoshenko, S. P. ; Goodier, J. N. Theory of elasticity. 3rd ed.

McGraw-Hill: New York; 1970.

[3] Murnaghan, F. D. Finite deformation of an elastic solid. J. Wiley &

Sons: New York; 1951.

Mechanical Relaxation of Liner Materials in Acetic Acid

Subtask 7 of Task 12136

J. C. Phillips

Polymers of varied chemical constitution and design are increasingly

used as barrier materials in hazardous materials storage ponds and

landfills. The essential purpose of these materials is to prevent or impede the leakage of liquid waste products into the underlying soil and

ultimately polluting the groundwater. In order to evaluate the efficacy

of liner materials one has to better characterize the transport and

mechanical properties behavior of these polymeric materials. The

initial investigation addressed the former problem using low and high

density polyethylene and the latter problem has been studied using

stress relaxation measurements to test the strain performance of three

563-55
liner materials (high density polyethylene, HOPE; chlorinated polyethylene,

CPE; polyvinyl chloride, PVC) both in air and acetic acid.

The experimental data for stress relaxation were obtained at temperatures

of 30, 50, and 72 °C. At the latter temperature (72 °C) stress relaxation

experiments were performed on HDPE as a function of elongation and concen- tration of acetic acid/H2 0 mixtures. Environmental stress cracking (ESC)

experiments at 60 and 90 °C were done for HDPE using acetic acid and

Igelpal as ESC agents. Additional experiments of recovery were also

performed for the three linear materials. In air at 30, 50, and 72 °C,

HDPE, PVC, and CPE exhibited a normal relaxation behavior over the

experimental time and strain range, i.e.,

log E(t) = log K + a log t

where K is a function of strain s and a is the slope of the log-log

plot. For HDPE the slope shows little if any variation with temperature

while the slope for PVC is slightly more negative and CPE has an even greater negative slope. In acetic acid the modulus was represented as a function of the characteristic time, t-t , of the sorption process (t

Q =

the time for initially bringing the liquid in contact with the sample),

i.e. ,

log E (t) = log K' + p log (t-t

Q

)

At 30, 50, and 72 °C, p approximately equals a for HPDE. At 72 °C, the

modulus for CPE was not measurable due to an extremely rapid drop in

modulus to zero immediately after stretching the sample. The only

significant changes of modulus in acetic acid for PVC versus that in air

also occurred at 72 °C for a strain of e = 0.89.

This investigation attempted to show how the relaxation modulus may be

used as a distinguishing parameter for different liner materials under

the influence of a given stress relaxation modulus, i.e., the ratio of

the modulus in liquid to that in air versus time. Further refined

studies may show this parameter to be quite useful in characterizing the

mechanical relaxation of potential liner materials.

Crystal Growth Kinetics and the Lateral Growth Habits of Polyethylene

Crystal

s

Subtask 8 of Task 12136

E. Passaglia and F. Khoury

It is well known that when polyethylene crystals are grown from solution

they become more elongated in the direction of the b crystallographic

axis the higher the temperature of growth. At high temperatures the

crystals are bounded laterally by (110) and (200) crystallographic

faces. The latter faces become longer relative to the (110) faces the

higher the crystallization temperature. At low temperatures and in some solvents, notably xylene, the (200) faces are not present. The crystals

are bounded only by (110) faces, and they exhibit the familiar lozenge

habit. The ratio of the length of the crystal in the b crystallographic

direction to its length in the a crystallographic direction, which we

563-56
denote by r, the aspect ratio, is thus a measure of the habit of the

crystal. The value of r ranges from about 0.66 for the lozenge habit to

five or higher at high temperatures in poor solvents.

At steady state growth, r is related to the rates of growth normal to

the (110) and (200) faces of the crystal by the simple equation

r = G 110 /(CoseG200

), (1)

where G

110 and G200 are the rates of growth normal to the two faces, and

0 is the angle between the b direction of the crystal and the normal to

the (110) face. Since r varies with temperature, G

110 and G200 must

have different temperature dependencies. The growth rate G depends upon

several material parameters, the most important of which are the surface

energies, and several theoretical parameters, most important among which

are the length of the substrate for nucleation, L, in regime I crystallization and <t> , the fractional assignment of the free energy of crystallization to forward and backward reactions in the stem deposition process in

both regimes I and II.

An analysis of the temperature dependence of crystal habits on the basis

of Eq. (1) allows the possibility of investigating the values of the

various parameters--particularly the determination of the relative

values of surface energies associated with stem deposition and folding

for the two crystal surfaces, and the effect of <() upon the analysis.

Writing Eq. (1) explicitly we obtain for regime I crystallization (r,)

and regime II crystallization ('f'jj)-

In rj = In Cj + In

L110 2(a/2)b<Jxj

110

’200 kT (1-P)

. . no no 4d no CTe

CT

AhAT kT/T°

a/2

J 110

V p-i

(2a)

In r^j = In Cjj +

(2<t>-l) (a/2) b ct

kT

no „ . no no

. 2d

100 °e ° a/2

AhATk T/T 110

Y P-1 >(2b)

where the symbols have the following meaning:

Cp C

II

: ratl

* os lattice parameters (slightly temperature dependent).

L 100 , L2 oo : The length in which one nucleation event occurs for the

(110) and (200) faces in regime I crystallization.

563-57
a,b,d 110 : The lengths of the a and b axes, and the (110) interplanar

spacing in the crystal.

a

110

, a

e 100 : The lateral and end surface free energies associated with the

deposition of a stem and folding of the chain on the (110)

surface of the crystal.

p: a

200 /ct 110

e e

y: q200/q100

Ah: Heat of fusion of extended chain crystal, per unit volume.

T°: The dissolution temperature of the extended chain crystals for the

given molecular weight and solvent system.

<{>: Parameter that assigns a fraction of the free energy of crystallization

to the forward reaction and the remainder (1 - <j>) to the backward

reaction in each deposition step.

Before analyzing experimental data according to Eqs. (2a) and (2b) some decision must be made about L 110 and L20 o- First, if these correspond

to the lengths of the respective crystal edge, then it is easy to show

that growth rates are exponential, and not linear as observed experimentally. In order to obtain linear growth, L has to be a constant. Second,

whatever the physical significance of L, we have no basis for assigning

a different value to L 110 and L20 o- Hence we take them to be equal.

The analysis was carried out on data by Blundell and Keller [1] and

Valenti and Pedemonte [2] for the crystallization of Marl ex 6009 in

xylene at various temperatures and in 0.01 percent and 0.1 percent

solutions. This is the most extensive data set available for which T°

is known as a function of concentration and molecular weight.

The results are as follows:

(1) If y = 1, i.e., if the lateral surface energy for deposition on (200) is the same as that for deposition on (110), and if p is not

temperature dependent, no fit can be obtained for any values of p. This holds for both regimes and for all values of <}>. This means that at least two parameters for any given are necessary to fit

the data. Two parameters can be obtained in the following two ways:

(a) y = 1> P is temperature dependent, p = p (1 + CT); (b) y ^ 1;

p i- 1; but both are temperature independent.

(2) Data analysis for case (a).

Analysis of the data in this case gives the following results:

(a) The value of p

Q depends upon the value of $ chosen for the

analysis, and the crystallization regime assumed to control growth.

However, in all cases, at a reference temperature of 338 K, p Q

> 1

its value ranging from 1.01 to 1.1 depending on $ and the solution

concentration of the data set. The temperature coefficient is

positive in all cases except = 1, where it is small and negative.

563-58
It is argued that the temperature coefficient should be negative,

since as temperature increases, the polyethylene lattice tends

toward the hexagonal where the distinction between (110) and (200)

planes disappears.

(3) .Analysis in case (b).

In this case, <J> has striking effects. For regime II analysis, at

(J) = 1/2, p and y show discontinuities. For the regime I analysis, at

<j> = 0, p becomes infinite and y becomes zero. The only consistent

data set are obtained at p = 1. Here p has values that range from

1.1 to 1.2. However, y has values slightly greater than unity for

regime I analysis and slightly less than unity for regime II analysis.

(4) The effect of solution concentration.

The data chosen for analysis were obtained at concentrations of

0.01 percent and 0.1 percent. This change in concentration changes

T^J from 377.9 K to 378.5 K for the 0.01 percent and the 0.1 percent

concentrations, respectively. The change in r with concentration

predicted by kinetic theory is exactly the opposite of that observed.

At a constant temperature, r is predicted to decrease with increase

of concentration; the data of Blundell and Keller and Valenti and

Pedemonte show it to increase. If these data are accepted as correct, the results would indicate changes in y and/or <J) with

concentration.

N (5) Conclusions:

The following tentative conclusions may be drawn from the analysis

(a) a

e 200 > ae 110 --The fold energy for deposition of stems on the (200)

face is of the order of 10 percent greater than that for deposition

on (110).

(b) ct200 ~ a

110 --The lateral surface free energies are approximately

equal. The actual relative values cannot be established until the

crystallization regime question for these crystals is settled, and

the theoretical question of the value of <|) is answered.

(c) It is very probable that ct 200 has a slightly different temperature

dependence than ct6

110 .

(d) The values of 0 and L are outstanding problems in the kinetic

theory of polymer crystallization.

(e) The kinetic theory predicts a different concentration dependence of

r than that observed by Blundell and Keller and Valente and Pedemonte

unless the surface energies change with concentration and the

change is different for different crystal faces.

563-59
(f) While no specific analysis was carried out on the effects of molecular

weight, some remarks on its effect may be made. For a given solvent

and concentration, theory predicts an increase of T° with molecular

weight. Hence, at constant temperature at a given concentration, r should decrease with increase of molecular weight, absent any

change of p or y with molecular weight. The data in references [1]

and [2] show an increase of r with molecular weight. The opposite

effect is found by Takamizawa et al. [3] in xylene, and by Khoury

[4] in other solvents.

[1] Blundell, D. J. ; Keller, A. J. Macromol. Sci.-Phys. B 2: 337; 1968.

[2] Valenti, B. ; Pedemonte, E. La Chimica e Industria 54: 112; 1972.

[3] Takamizawa, K. ; Urabe, Y. ; Hara, T. Reports on Prog, in Poly. Phys.

XII: 179; 1969.

[4] Khoury, F. A.; Bolz, L. H. Bull. Am. Phys. Soc.

The Morphology of Polyethylene Crystals Grown From Solution

Subtask 9 of Task 12136

F. A. Khoury and L. H. Bolz

The lateral growth habits and nonplanar conformations of polyethylene

crystals grown from dilute solutions are known to vary depending on the

crystallization temperature, other factors remaining equal (solvent,

mol. wt. , polymer concentration).

We have previously reported that crystals exhibiting "truncated" lateral

habits and having aspect ratio r* in the range 1.6 to 6 were grown from

heptyl acetate and dodecanol. The following effects of temperature,

molecular weight, and solvent on the aspect ratio of crystals were

observed. (1) As expected, for a given molecular weight, concentration,

and solvent, the higher the crystallization temperature the higher r. In addition, whereas the crystals with low r exhibited well defined

(110) and (200) faces, the (200) "edges" of the lamellae tended to

become curved, and all the more pronouncedly so, the larger r. (2) For

a given crystallization temperature, concentration, and solvent, the

higher the molecular weight, the smaller r. (3) For a given crystallization temperature, concentration, and molecular weight, r was larger for

crystals grown form heptyl acetate than dodecanol, which is a poorer

solvent. These results clearly illustrate the strong dependence of r on the undercooling AT.

Our current investigations are aimed primarily at determining the

nature of the conformations of crystals of various fractions using

scanning transmission electron microscopy and selected area electron

diffraction. Our earlier studies had been limited to an examination of

crystals of Fraction I (Mol. wt. 11,400) grown from dodecanol at 115 °C.

*r = ratio of the dimensions of the lamellae parallel to the [010] and

[100] directions.

563-60
These crystals had an aspect ratio r ^ 6. The main feature of interest

was that the majority of the crystals had asymmetri c conformations,

i.e., the two halves of the lamellae situated on opposite sides of the

long axis were not mirror images of one another. More recently, we have

found this to be the case for three other species of crystals with

smaller aspect ratios. These were: (1) Crystals of Fraction I, r = 3.5

(grown from heptyl acetate at 105 °C); (2) Crystals of Fraction I,

r = 3.2 (grown from dodecanol at 112 °C); and (3) Crystals of Fraction

III, Mol. wt. = 100,500, r = 2.5 (grown from heptyl acetate at 112 °C).

It remains to be determined how widespread is the manifestation of this

phenomenon among the crystals (of the various fractions) whose aspect

ratio is in the range r = 1.6 to 6.

Interest in asymmetric crystals such as the ones we have observed so far, stems from the not unreasonable speculation that they have features

in common with, and hence will shed some light on, the nature of the

experimentally less accessible constituent lamellae in axial i tic and

spherulitic structures formed in bulk polymer.

The Energies of (110) and (200) Folds in Polyethylene Crystals

Subtask 10 or Task 12136

F. A. Khoury, J. Mazur, and B. M. Fanconi

The energies of (100) and (200) folds in polyethylene crystals are of

interest in connection with the elucidation of the origins of two features

of the morphology of solution-grown as well as melt-grown crystals.

These two features are: (1) The occurence of fold staggering resulting

in the formation of hollow pyramidal, tent- like, or otherwise nonplanar

lamellar crystals; and (2) the dependence of the lateral growth habits

of the crystals on the crystallization conditions. The particular

feature of interest in the latter context in the dependence of the

aspect ratio r of the lamellae on the crystallization temperature (see

previous Subtask, "The Morphology of Polyethylene Crystals", F. A. Khoury and L. H. Bolz).

As an initial step in examining the possible relationships between the

above mentioned morphological features and the (110) and (200) fold

energies, minimum energy conformation for models of such folds were

computed. Adjacent reentry was assumed for the following three cases:

(1) Isolated (110) and (200) folds at the surface of a lamella; (2) (110)

and (200) folds surrounded by and interacting with kindred folds situated

in the same and adjoining (110) and (200) planes, respectively. In (1)

and (2), the stems bridged by the folds were assumed to be at right

angles to the crystal surface); and (3) (200) folds surrounded by neighboring (200) folds packed in a staggered manner, i.e., the crystal

surface was assumed to be (201).

The computations of fold energies involved the summation of pair-wise

interactions calculated as a function of interatomic separations r for

both inter and intra molecular interactions. The nonbonded carbon-carbon,

carbon-hydrogen, and hydrogen-hydrogen interactions were assumed to be

_D r 0 represented by Buckingham type potential functions (E = Ae -C/r ).

563-61
Interactions for r > 0.6 nm were neglected. The empirical parameters

(A, B, and C) of the Williams IV set were used. Additional energy

contributions due to bond angle and bond stretching deformations, as well as due to rotations around backbone bonds were also computed. A

generalized Urey-Bradley force field was assumed for these intramolecular

interactions. The minimum energy fold confromation was determined in

each case using the Newton-Raphson iterative procedure. Only the atoms

in the folds were allowed to change in the energy minimization process,

the coordinates of the carbon atoms in the stems underlying the folds were

o held fixed. The polyethylene unit cell parameters used were a = 7.4A,

o o b = 4.95A, c = 2.536A, a = p = y=90 deg, setting angle 0 = 48 with respect

to the b-axis.

In the case of isolated folds (Case I above) the (200) fold energy was lower than that of the most favorable (110) folds by ^ 1 kcal/mole

(in close agreement with [1]). In contrast, when interfold interactions were taken into account (Case II) the (110) fold energy was ~ 3 kcal/mole

lower than the (200) fold energy. This difference was determined from

a comparison of the most favorable lateral packing arrangement of

(110) folds with that of (200) folds. Staggering of (200) folds

(case III, lamellar surface (201)) results in a lowering of the fold

energy. The energy corresponding to the most favorable lateral packing

of staggered (200) folds was ~ 0.9 kcal/mol lower than that for unstaggered

(200) folds.

It is interesting that the computations of fold energies summarized above,

in which the interactions between neighboring folds are taken into account

(Cases II, III), indicate that the energy of (200) folds is higher than that

of (110) folds. This result of the comparison of the most energetically

favorable models for each type of fold, and the results of the analysis

(based on the kinetic theory of polymer crystal growth) of the changes in

the lateral growth habits of polyethylene crystals grown from xylene solutions

as a function of undercooling, are in qualitative agreement (see Crystal

Growth Kinetics and the Lateral Growth Habits of Polyethylene Crystals,

E. Passaglia and F. A. Khoury).

Calculations are at present being carried out to determine the effect of

staggering on the energy of (110) folds.

[1] Corradini, P. et al . Macromolecules 4: 770; 1971.

Durability of Elastomers Used in Geothermal Energy Production

Subtask 11 of Task 12136

R. W. Penn

The objective of this project was to develop a rational technique for

measuring the rates of breaking and formation of chemical bonds affecting

the mechanical properties of elastomeric sealant materials aging under

geothermal down-well conditions. The project was to include a theoretical

and experimental approach following the treatment developed by Tobolsky,

et al. as modified by Kearsley and reported in detail previously. This

563-62
treatment relies upon a simple modification of the kinetic theory of

rubber elasticity

\f

x

- pf

M = NkT[g(A) - g(p)] (1)

where A, p are stretches, f^ and f^ are the forces acting on the faces

of the prism perpendicular to stretch A and p respectively, k is Boltzmann's

constant, T is absolute temperature. g(A) is an arbitrary function

which is to be measured by experiment. This equation is consistent with

a recent phenomenological theory of Valanis and Landel if we equate

their Aw' (A.) with our NkTg(A). In the case of simple extension, f and

r

f acting on the force free sides of the sample are zero, p and v are

equal to A"1/2 (because of the assumed constant volume) and Eq. (1)

becomes

Af = NkT h(A) (2)

where f is the tensile force producing the stretch A and h(A) is given

by

h(\) = g(\)-g(\' 1/2

) (3)

Corresponding equations can be found for other homogeneous isochoric

deformations (such as biaxial extension or pure shear) giving the forces

in terms of the experimentally determined function g(A).

When N, the number of segments between intermolecular bonds per unit

volume, does not change with time, Eq. (1) corresponds to a perfectly

elastic material which will exhibit no stress relaxation. For elastomeric

materials, this might be appropriate to describe equilibrium isothermal

behavior at room temperature. That is, if we look at the behavior of an ordinary rubber at room temperature stretched from the undeformed state

and held for a few minutes until the modulus settles down to the "rubbery

plateau", the forces required to hold it stretched will then be almost

constant in time and Eq. (1) will apply. The stress relaxation occuring

at shorter times (sometimes called "physical" stress relaxation to

distinguish it from "chemical" stress relaxation) is presumably caused

by the slipping of intermolecular entanglements and other temporary

bonds. The equilibrium stress of the "rubbery plateau", however, probably

reflects chemical cross-links or other, more permanent bonds between

segments. With time, in an agressive atmosphere such as in geothermal

down-well conditions, even these chemical crosslinks can be expected to

break down and, as a result of the chemically active atmosphere new crosslinkages might be formed simultaneously. Suppose a sample of

material is aged in such an atmosphere, then the quantity N of Eq. (1)

will change in time reflecting the net change in crosslink density and

giving rise to softening or embrittlement of the sample. Consider the

following experiment. A virgin sample of elastomer with N

q

effective

segments between crosslinks per unit volume is extended to a stretch, A,

and the tensile force (when it settles down to a steady value) is measured.

The sample is then allowed to recover and is then aged for a fixed time,

t, in some atmosphere of interest. During this time the atmosphere will

563-63
cause crosslinks to break and to form or chain scission to occur so that

N will change to a new value, N

q + n(t)-m(t), where n(t) is the number

of segments formed in time t per unit volume and m(t) is the number of

segments destroyed. At this point, the sample is removed from the aggressive atmosphere and the measurement of simple extension is repeated in the

inactive laboratory atmosphere. If the \ and T apply for each simple

extension measurement, Eq. (2) applies in each case with only f and N varying and we can write

f(t)/f

Q = (Nq + n(t) - m(t))/NQ (4)

where f and N

q refer to the virgin sample and f(t), n(t), n(t) refer to

the sample aged for time t. Thus, this experiemnt can be used to monitor

the total change in segments per unit volume induced by the aging.

The present report covers experimental work consisting of the assembly of

apparatus to simulate geothermal down-well conditions and some preliminary

tests conducted on two samples of Y267 EPDM high temperature packer seal

formulation (Y267-XXX11-6, and -7) which were supplied by L' Garde, Inc.

The environmental apparatus consists of a pressure vessel constructed

from Hasteloy C-276. It was manufactured by LECO Corporation, Tem-Pres

Division. It is rated for use up to 9000 psi at temperatures up to

400 °C. It provides a working chamber two inches in diameter and ten

inches long. It can be placed in an electrical resistance furnace

supplied by the same company together with a temperature controller.

The pressure vessel is connected to a cylinder gas source with provisions

for purging, bleeding, etc. The tubing and valves, etc. are all high

pressure stainless steel construction rated up to 10,000 psi for atmosphere

not hostile to type 303 stainless steel.

Test specimens were die cut from the 6 in. square sample. The specimens were straight strips 0.25 in. wide and 2.75 in. long. They were approximately 0.080 in. thick. They were held in small simple clamps each

consisting of two small bars of aluminum between which the specimen

could be held by means of two steel screws. The grips were designed so that specimens could be held at constant extension in a simple slotted

cylinder device which would permit up to twelve specimens to be held in

the pressure chamber simultaneously. The grips could also be attached

simply to test fixtures which fit our hydraulic powered test machine.

This machine is controlled by a dedicated mini-computer. A BASIC language

program was modified to perform a stress relaxation test in uniaxial extension. The samples were loaded into the machine and stretched 10 percent.

The tension in the specimens was then measured at times between 0.05 second

and 100 seconds after the loading. We were thus able to cover approximately

two and one half decades on a logarithmic time scale and the stresses were

calculated.

Four specimens of each of the EPDM elastomers mentioned above were prepared.

Their stress relaxation behavior was measured. They were then stretched by

various amounts from zero to thirty percent. They were placed in the pressure

chamber in dionized water. The system was then purged with nitrogen at

563-64
2000 psi four times to remove oxygen. The heater was turned on and during

the time (approximately one hour) that the system was heating to 265 °C the

system was purged twice more. During these purges the water was permitted

to boil. The system was held between 260 and 265 °C for approximately one hour and then allowed to cool to room temperature. All of the specimens

had failed at the clamps. Those which were unstretched showed severe crack damage in the area of the clamps. This disappointing result is

probably due to the large localized biaxial strains imposed by the clamping.

The specimens were then reclamped and again tested in stress relaxation tests

at 10 percent strain. The form of the stress relaxation curves had not

changed but the level of stress required to maintain the strain had reduced

by approximately 15 percent. There was no significant correlation of this

decrease with the level of stretch. This may only indicate that they all

failed early in the test and that they all spent most of the time at zero

stretch. It appears that it will be necessary to redesign the specimens to

avoid the high strain concentrations at the clamps. This might be accom- plished by the use of dog-bone shape specimens or by the use of ring shape

specimens which could be die cut from sheets. This would avoid the nonuniformity problems which we experienced in working with o-ring samples.
Thermocouples Capi 1 lary

Pressure Seals

Temperature Controlled

Fluid

A1 ignment

Bushings

Thrust

Bearing

totatable Shaft

Figure 1 Schematic of the Torsional Dilatometer.

563-66
Figure 2 General schematic of the torsional dilatometer. CO = optical

encoder, M = motor; BV = high precision gears; AT = drive shaft;

CF = normal force transducer.

Speed

Posi tioner

(AXUMERIK E)

Position

Speed

Control - er

~^

v Speed Sens

Tachometer

Measuring Impulses

(Speed & Position)

Figure 3 Schematic of servo-control system for torsional dilatomer.

M = motor; DT = tachometer; CO = optical encoder. The Axumerik E represents the digital system which performs the calculations

used to control the angular position.

563-67

PROCESSING AND RELIABILITY OF POLYMER COMPOSITES

Task 12137

One of the most rapidly growing areas of high payoff polymer applications

is composite materials. The addition of a reinforcement, as either

particles or fibers, to polymers can dramatically improve their performance, and as a result they can be utilized in a wide range of generic

applications where the requirements are beyond the capabilities of

simple polymers. This expanded potential has led to increased usage in

many diverse areas ranging from aerospace to automotive. Two major

factors behind the expanding application of these materials are that

their use is highly energy efficient and this can significantly reduce

the need for critical materials such as cobalt and chromium whose limited

supply is of critical concern to the national interest.

Although composite materials have great potential, the same multicomponent composition that is responsible for their high performance also

gives rise to numerous problems with regard to the processing, fabrication

and prediction of failure behavior or service life. Since the composite

field is still at an early stage of development, many of these problems

can be directly attributed to a lack of basic knowledge, and adequate

test methods in the composites area. In response to this need, a new Task has been initiated during 1982. The objectives are to carry out

long range research to provide industry and other Government agencies

with test methods, material property data and failure prediction models

that are essential if the full potential of these materials is to be

achieved. In line with the two primary problem areas mentioned above,

there are two major thrusts in this Task. The first seeks to gain a better understanding of the basic science involved in processing and

fabrication of these materials while the second addresses the development

of the basic science concepts, methods, and data needed to assist in

improving durability and enhancing the capability for failure predictions.

During the first year Task programs have been developed to address both

areas of concern. Several projects are studying cure, i.e. the chemical

reactions that occur during processing and represent the most important

factor in successful fabrication. Of special interest are experiments

investigating rapid cure and the curing of films since these areas are

of great practical importance. Another program is developing quality

control techniques for raw materials, an area of great concern to industry

The failure behavior of both particle and fiber reinforced polymers is

also being studied with special emphasis on the development of techniques,

such as X-ray scattering, which can provide information about the state

of the materials prior to fracture. To assist in conducting this broadly

based effort three outside experts spent time working in the Division

during the last year: Dr. Raganathan, an industrial research associate

from Martin Marietta; Dr. James Koutsky, an Intergovernmental Personnel

Act employee from the University of Illinois; and Dr. Anthony Kinloch,

a foreign guest worker from the Ministry of Defense in England.

563-69
Failure Behavior of Particle Reinforced Polymer Composites

Subtask 1 of Task 12137

D. L. Hunston, A. J. Kinloch, and G. W. Bullman

Most of the polymers used in structural application are inherently

brittle and must be reinforced or toughened. One empirically developed

method that has proven to be quite successful is the incorporation of

small particles of a softer material in a matrix of the brittle polymer.

Although composite materials of this type often have very high fracture

energies their failure behavior is usually quite complex and involves

large viscoelastic effects.

In an effort to gain a fundamental understanding of the failure behavior

of such materials, NBS is currently studying two different model systems:

a polysulfone filled with polytetrafl uoroethylene particles and an epoxy

with epoxy/polybutadiene particles. The first system is of interest to

the Navy for certain seal applications while the second serves as a model for most commercial structural adhesives. The program focusses on developing test methods for such materials and studying the mechanisms

of failure. As part of this effort a joint program was initiated in

1979 with scientists from the University of Illinois and the Ministry of

Defense (Waltham Abbey Laboratory) in England1 ”4

. During the last year,

Dr. A. J. Kinloch from Waltham Abbey spent 3 weeks at NBS as a guest

worker to help coordinate results from various parts of the program. As

a result of this visit the empirical failure model developed two years

ago in this program has now been extended to 4 different elastomermodified epoxy formulations. The most significant aspect of this development is that the temperature dependence for all 4 systems could be

described with a single Arrhenius type activation energy whose value was

identical to that obtained from yield experiments. It has previously

been suggested that yielding was a crucial step in the toughening mechanism

for these materials but this provides the first direct evidence for a relationship between the two properties.

[1] Hunston, D. L. ; Rushford, J. L. ; Wang, S. S. ; Kinloch, A. J. Proceedings of the SPI Conference on Reinforced Plastics/Composites.

Washington, DC; 1982, January.

[2] Bitner, J. L. ; Rushford, J. L. ; Rose, W. S. ; Hunston, D. L.

;

Riew, C. K. J. Adhesion 13: 3; 1981.

[3] Kinloch, A. J. ; Shaw, S. J. ; Hunston, D. L. Proceedings of the

International Conference on Deformation and Fracture. Cambridge,

England, 1982, March.

[4] Hunston, D. L. ; Wang, S. S. ; Kinloch, A. J. Organic Coatings and

Plastic Preprints 47: 407; 1982.

563-70
Interlaminar Fracture of Composites

Subtask 2 of Task 12137

D. L. Hunston, G. W. Bullman, and J. A. Koutsky

A major area of concern in the use of continuous-fiber reinforced

composites is delamination, that is the growth of cracks between the

layers of fibers. Delamination can substantially reduce the performance

of composites in numerous ways but compression strength is particularly

sensitive to this type of damage. The conventional polymeric

matrix resins, i.e., the material that binds the fiber together, are very brittle and therefore subject to damage particularly when loaded

by impact. This damage involves matrix cracks which can easily

grow into large areas of delamination. The problems this can generate

in practical applications have led to a widespread interest in developing

polymeric matrix materials with improved resistance to both initial

damage and subsequent growth of this damage into a delamination. In

addition, there is a need to develop design data that can be used to

predict the growth rate of a delamination. Unfortunately, although

a number of test methods are now being used, few if any have been

developed to the extent that they can provide the quantitative

information that is needed.

In response to this problem, a joint program has been established

among researchers at NBS, NASA Langley, the University of Illinois,

and several composites manufacturers. As part of this program, NBS is

examining various test methods for determining interlaminar fracture.

The tests employ specimens with either rectangular or triangular geometries. A precrack is generated between fiber layers in the specimen and

an increasing load is applied perpendicular to the precrack so that subsequent crack growth occurs between the layers of fibers. The critical

value at which this crack growth begins is noted and converted to a fracture energy using appropriate equations.

During the last year, the program has studied the effects of specimen

size, geometry, and lay-up (the sequence of fiber layers and their

orientations). Data from these tests have been correlated with the

stress analysis work at the University of Illinois and the composites

testing program at NASA Langley. These results have led to a series of

guidelines for the design of test specimens when the polymeric matrix

is a brittle material. Future work will focus on testing composites

made with toughened matrix materials and thermoplastic resins. The

effects of loading rate, temperature, and environment on the fracture

test will also be examined. This will help establish both the

validity of the test methodology and a data base of information for

model systems representing the various types of polymers.

563-71
A Non-Destructive Technique to Monitor Cure of Adhesive and Composite

Resi ns Subtask 3 of Task 12137

D. L. Hunston and J. A. Koutsky

s In applications such as fiber-reinforced composites and adhesives the

polymer must be fluid in the early stages of fabrication so that

the proper flow, leveling, wetting and spreading at interfaces, etc. can

be achieved. The polymer must then harden by cooling, solvent loss, or chemical reactions to form a rigid material. In most cases

the successful fabrication of a final product requires that associated

changes in mechanical properties take place at the appropriate times and

rates. It is desirable therefore to have nondestructive techniques that

can monitor these changes as they occur. Unfortunately, this is gnerally

very difficult, particularly since many of the applications involve

thin films, whose mechanical properties are difficult to measure and

cannot usually be predicted from experiments on bulk samples.

To address this problem, an effort is being made to develop a new method

for nondestructively characterizing thin films. During the last year an ultrasonic shear wave technique has been studied as a candidate test

method. The experiment involves the propagation of a shear wave in a quartz plate coated with the thin polymer sample. By monitoring the attenuation of the wave in the strip, it is possible to follow changes that

occur in the coating. The first samples tested were an epoxy-type polymer

that cures by free radical initiation. Figure 1 shows a plot of attenuation vs curing time for two formulations containing the same epoxy but

with different concentrations of accelerator. The experiments clearly

show that there is an initiation period prior to the onset of cure. The

rate of cure influences the width of the transition while the ultimate

attenuation level depends on the structure of the cured film among other

factors. When the accelerator concentration is changed both the reaction

rate and the induction period are altered but the ultimate attenuation

level remains the same. This type of information can be crucial in

designing epoxy-based adhesives and composites.

The results to date indicate that this technique can be used to qualitatively monitor changes that occur during the liquid-to-solid transition

in important polymer systems. During the next year an effort will be

made to quantify this test. As part of this effort the measurement capability will be expanded to permit the determination of velocity as well

as attenuation. In addition, the program will investigate the possibilities for coupling this technique with other methods such as dielectric

tests that may be more amendable to process control measurements. The

information provided by this coupling would make both measurement techniques more useful.

563-72
Measurement of Microvoids and Microcracks in Composite Materials Using

Small Angle X-ray Scattering Technique s Subtask 4 of Task 12137

W. L. Wu

Small angle x-ray scattering (SAXS) has been used extensively in structural

characterizations of heterogeneous systems. Most work, both theoretical

and experimental, deals with systems composed of only two phases. A

theoretical development treating systems of three phases (matrix, reinforcing fibers or fillers, and microcracks) has been advanced. It is

shown that the volume content and the characteristic lengths of the microcracks or voids can be determined from the angular dependence of the x-ray

scattering intensities. The analysis are valid for both deformed and

undeformed specimens. Incorporating the experimental data, useful information regarding the size and content of microcracks within damaged particulate composites has been obtained.

Industrial Research Associate Program on Thermal and Spectroscopic

Properties of Polymer-Based Composite Materials

Subtask 5 of Task 12137

B. N. Ranganathan, J. H. Flynn, and B. M. Fanconi

Dr. Ranganathan (Martin Marietta Corporation) completed a six-month

Research Program in the Polymer Science and Standards Division. During

this time, extensive use was made of NBS equipment to evaluate potential

test methods as a basis for the establishment of quality control procedures

which promise to significantly reduce the cost of inspecting the Thermal

Protection System (TPS) which insulates the External Fuel Tank for the

Space Shuttle.

The TPS insulation consists of a superlight ablator composite material,

approximately 1/2 in. thick, that is applied directly onto the outer

surface of the aluminum external tank, and, on top of the composite

ablater material, approximately 3/4 in. thick polyurethane foam is

applied for additional insulation. TPS insulation serves an important

function in that it prevents ice formation, and also minimizes boil -off

of the cyrogenic liquid fuels.

The composite superlight ablator layer of the thermal protection system

is functionally more critical than the polyurethane layer. The composite

consists of silicone resin, glass fibers, carbon black, phenolic microspheres, silica microspheres, cork, etc., of which silicone resin is the

most important component for it serves as the binder that holds together

all the other components of the composite, and further functions as an adhesive that bonds the composite to the aluminum surface of the external

fuel tank.

The present investigation is concerned with the evaluation of silicone

resins. The main purpose of this research was to develop effective

quality control procedures using state-of-the-art techniques that are

rapid, accurate, and more reliable than the currently used methods, so that a "good" lot can be distinguished from a "bad" lot of material.

563-73
This distinction of a "good" from a "bad" material is of immense importance, as it alleviates expensive repairs that are labor intensive, and

results in a very cost effective external tank program.

Two types of silicone materials were evaluated as a part of this investigation. Both types are purchased commercially, and as such the exact

chemical formulations are proprietory in nature. Type I silicone is

fast curing (gel time--10 mins) and low strength (tensile strength

approximately 50 psi), while Type II is slow curing (gel time--several

hours) and high strength (tensile strength approximately 1000 psi); the

higher strength of the latter is due to the presence of a filler material.

Both types of silicones are two component systems, and the curing mechanism

is via an addition reaction between silane (component-B) and vinyl (component-A) groups; in addition, component A contains a platinum catalyst.

In manufacturing, an A to B ratio of 10:1 is used.

Two techniques; namely, DSC and FTIR, were evaluated for their viability

as effective quality control procedures for the intended purpose.

Evaluation of individual components was not possible using DSC; that is, no useful thermal property information was obtainable in the temperature

range of interest. Therefore, DSC was used solely for studying the

curing reaction. On the other hand, FTIR permitted the evaluation of

individual components as well as the curing reaction.

Results obtained to date indicate that FTIR is a viable quality control

technique. An attempt will be made to use this technique in the future

at the Martin Marietta quality control laboratory for the evaluation of

polymeric raw materials prior to their use in manufacturing.

The establishment of FTIR as a viable quality control technique with its

intended future application and attendant benefits at Martin Marietta

Aerospace is a direct result of the research associate's work at NBS.

Analysis of Rapid Thermoset Resin Curing

Subtask 6 of Task 12137

G. A. Senich

Thermosetting resins are distinguished from the thermoplastics by the

three-dimensional nature of the chemical linkages formed in these materials

during the cure process. A network of chemical bonds is formed irreversibly by heat or chemical means during curing or cross-linking processes

and renders the material substantially infusible and insoluble. This is

in contrast to thermoplastic materials which are capable of being repeatedly

softened when heated and hardened when cooled. Articles fabricated from

thermoset materials are generally insoluble, resistant to dimensional

changes and flow, and able to withstand high temperature heating without

mel ti ng.

Thermosets are considerable articles of commerce. Their usage in the

U.S. has been estimated to amount to over 1.1 billion pounds in 1979.

The most commercially important thermosetting resins are phenolic-,

urea-, and melamine-formaldehydes, alkyds, polyurethanes, epoxies, and

polyesters. These materials are commonly used as the polymeric matrix

563-74
of highly filled structural composites, a market which amounted to over

2 billion pounds of fabricated material in the U.S. for 1979. Composite

parts are produced by molding or laminating operations which generally

require either a long time in a closed mold or press at a high temperature and pressure or a lengthy post-cure outside the mold, again at high

temperatures. These long times for thermal curing, on the order of one

to several hours, restrict the rate of production of composite articles.

Rapidly curing thermoset resins could greatly reduce production time and

permit a large increase in the volume of fabricated composite output.

Another area in which rapid curing is of preponderant importance is the

printing process. At typical paper speeds, a thermoset polymeric ink

has only a one to ten second curing period for achieving sufficient

mechanical strength to allow the substrate to be wound onto a takeup

roll without damage to the printed image. Natural -product based inks are now used in intaglio currency printing operations and usually provide

acceptable performance. However, it is desirable to investigate rapidly

curing synthetic thermosetting resins that could alleviate some of the

difficulties encountered with material variability and undesirable solvents

in printing with the current inks as well as others anticipated to occur

with the introduction of new printing machinery.

A program has been initiated to assess the current state of rapid-cure

thermoset matrix resin science and technology. Suitable example systems

of interest, principally epoxies, acrylated oligomers, and unsaturated

polyesters/acrylics, are being examined. Test methods for chemical or functional group characterization by FTIR, and mechanical characterization by rheometer and viscometer are being developed and coordinated to

provide an understanding of how chemical reactivity and mechanical

properties are related during the curing process. Novel methods for

studying the kinetics of rapid curing, such as monitoring the mechanical

property changes of a thin, curing film on a quartz substrate by ultrasonic

shear wave propagation, are also being employed. The program will

provide a better understanding of the chemistry of processing thermoset

polymers and aid in the identification of possible candidate materials

for special applications, such as rapidly curing synthetic thermosets

suitable for use as ink vehicles, matrix resins which could increase the

rate of production in the manufacture of composite articles, and repair

formulations for quick mending of composite parts.

Degree of Polymerization of Thermoset Resins Used in Composites

Subtask 7 of Task 12137

W. L. Wu and B. M. Fanconi

Physical properties as well as the resistance to adverse environments

of thermoset resins depend strongly on the degree of polymerization

(state of cure). The curing process of thermoset resins is believed to be

incomplete if the curing temperature is well below the glass transition

temperature

00 ( y

of the polymers in their completely cured states.

situation is commonly encountered in practical cases.

Thi s

563-75
A FTIR technique was developed for monitoring the degree of cure and was applied to assess the degree of polymerization of commonly used thermoset

resin systems. Cure characteristics were examined as a function of type

and amount of initiators and accelerators, as well as the flexibility of

the prepolymer. It has been found that only a limited amount of polymerization occured after the vitrification points. The degree of polymerization is mainly controlled by the viscosity of the monomer instead of

the type or amount of the initiators.
(wo/cUu) NOIlVn.NBliV

563-77

Figure

1

Cure

data

for

the

epoxy/accelerator

system,

dashed

line

for

uncoated

strip,

x

for

0.25

percent

accelerator,

and

for

0.35

percent

accelerator.

ADDITIVE MIGRATION AND CHEMICAL DURABILITY OF POLYMERS

Task 12138

Polymeric materials find many high payoff applications in construction,

transportation, and electrical systems where long-term durability is

'essential to competitive performance. The growing use of polymeric

materials in these generic applications, generates a need for long-term

research aimed at providing a scientific basis for accelerated tests of

service life. In fact, a recent report by the National Research Council

states, "The lack of adequate measurement techniques for predicting the

service life of new materials and components is a major barrier to the

acceptance of polymeric materials."

To develop reliable methods for predicting the service life of polymeric

materials, we need to identify the scientific basis of (1) the rates and

mechanisms by which polymeric materials degrade under the appropriate

environmental conditions and (2) the rates and extents of the migration

of protective additives from polymeric materials. The collection and

interpretation of these two types of information have been the main

effort in this task.

Research this year on degradation mechanisms and rates includes investigations of the hydrolysis of polyesters and the use of thermo-gravimetry

to measure the rates and activation energies of the thermal degradation

of several polymers. In addition, we have initiated a collaborative

program with the Building Materials Division to investigate the kinetics

and mechanism of the photodegradation of PMMA, a polymer widely used for

solar cover plates.

Almost all useful polymeric materials have low-molecular-weight substances

incorporated in them to develop or maintain desirable properties. In

use, these substances inevitably diffuse through the polymer to some extent and may migrate out of the polymer entirely. The polymer is then

left with poorer properties or made more vulnerable to degradation and

failure. This is a major failure mode of polymers, and lifetime prediction

methods must explicitly include the rates of additive diffusion along

with the rates of the inhibited and uninhibited degradation reactions.

The number of commercially usable polymer-additive combinations is too

large to be considered efficiently on a case-by-case basis. The emphasis

in this task is, therefore, on the development of general principles or models of diffusion that are applicable to the widest range of generically

important systems. In addition, knowledge of the general principles

which control diffusion through solid polymers is important to the

design and evaluation of improved additive systems. Work this year on the migration of additives includes measurements of diffusion rates by

solvent extraction and by inverse chromatography and investigations of

slow diffusion in solid polymers and concentrated polymer solutions by

microfluorimetry and by a photobleaching technique.

563-79
Hydrolytic Degradation of Polyester Polyurethane Elastomers

Subtask 1 of Task 12138

D. W. Brown, R. E. Lowry, and L. E. Smith

Polyester polyurethane elastomers are useful specialty polymers. Unfortunately, their ester linkages are subject to acid-catalyzed hydrolysis.

Earlier, we investigated this process and developed kinetic schemes that

can be used to predict lifetimes of these polymers, with and without

carbodimide stabilizers.

In this year we investigated several additional aspects of this hydrolytic

degradation.

Published data indicate that cross-linked polyester polyurethanes in

magnetic tape binder may appear stable to hydrolysis at about 25 percent

relative humidity, RH, because of the equilibrium between ester hydrolysis

and esterification [1]. This equilibrium ought to be general for ester

hydrolysis and so may affect estimates of hydrolytic stability in other

polyester systems. We determined the equilibrium acid contents, [A ],

in three polyester diols and in soluble poly(butylene adipate) and

e poly(caprolactone)-based polyurethanes. Values of [

A

0

3 —1 are about

7xl0-4 mol/g at 25 percent RH. Molecular weight of the polyurethanes

equals [A ] _1

, about 1400, if there is one acid group per molecule. The

equilibrated polymers are weak, brittle, solids. Presumably the initial

crosslinks or perhaps reaction of acid with iron oxide made the polyurethane

appear more stable on the equilibrated tape.

Another study concerned the behavior of carbodiimide stabilizers. We had

observed that polyester polyurethanes consumed carbodiimide stabilizers

from three to ten times faster during hydrolytic aging than did the

polyester diols used to make the polymers. We made a poly(caprolactone)

di urethane diol from a 2:1 mixture of diol and diisocyante. This material

consumed carbodiimide during hydrolytic aging about as slowly as the

polycaprolactone diol. Thus, the difference in rates of carbodiimide

consumption was not explained but is not associated with the presence of

urethane in the polymer.

A third study was made of the effect of the initial acid content on the

rate of consumption of carbodiimide. We used the same number of moles excess carbodiimide over acid in two polybutylene adipate diols that

differed in initial acid contents by a factor of 20. The diol having

the higher initial acid content consumed the excess carbodiimide faster

during hydrolytic aging. Presumably this was due to hydrolysis of the

acyl area produced by reaction of acid and carbodiimide. At lower

initial acid contents this reaction apparently is not important because

uncatalyzed hydrolysis of ester also consumes carbodiimide. The result

indicates the practical importance of using low acid diols in making

polyurethanes, even if a stabilizer is to be used.

[1] Cuddihy , E. F. IEEE Trans. Mag. 16: 558; 1980.
Prediction of the Long-Term Stability of Polyester-Based Recording Media

Subtask 2 of Task 12138

D. W. Brown, R. E. Lowry, and L. E. Smith

PET is the base material in many information storage and retrieval

systems. We are investigating methods of estimating the useful lifetime

of PET in archival storage, under sponsorship of the National Archives.

Hydrolysis of the ester linkage is the most important cause of degradation.

Various samples are being aged under a variety of conditions. Samples

have been examined after aging at 55, 85, 100, and 115 °C at 25 to 100

percent RH. Gel permeation chromatograms were used to calculate molecular

weights. They indicate that about one scission/ original molecule (5 x 10”5 mol scission/g polymer) makes the polymer quite brittle. The

imprecision in molecular weight is such that scissions probably are uncertain by 1 to 2 x 10"5 mol/g. Thus, the gel chromatograph, which

consumes only about 5 mg of PET per determination, does not appear to

measure chain scissions with enough precision to anticipate embrittlement.

Efforts will be made to improve the precision of this measurement.

Acid contents were measured by potentiometric titration. The change in

acid content is about equal to the number of scissions, as is expected

for hydrolysis of a polyester. Acid contents are somewhat more precisely

known than molecular weights but measurement of the former requires

about 2 g of polymer. This is too much for use as a monitoring technique.

Attempts will be made to develop infrared and sonic methods of analysis.

Examination of Processes in Thermogravimetry

Subtask 3 of Task 12138

B. Dickens

Calculated vapor pressures have been used [1] in a first-approximation

model of the vapor above thermally degrading polyethylene [2]. The

results suggest that the "normal boiling" of large molecules in the

range C 3 q to > c 90 forces the rapid growth of bubbles in polyethylene

degrading at low pressures, and the bubbles grow to significant size

because the liquid is relatively elastic. The trend of decreasing

apparent overall activation energy with increasing pressure is ascribed

to contributions of low latent heats of vaporization from molecules up

to *\> C 30 , depending on the imposed pressure. The trends of vapor composition for various temperatures and pressures have been studied. In general,

both the temperature and the pressure should be as low as possible to

minimize the contribution of the latent heats of vaporization to the

overall activation energy and interference from bubbles in the molten

degrading polymer.

Table 1 gives the activation energies found [2] for thermally degrading

polyethylene, together with the associated pressures, temperatures, and

apparent orders of reaction (calculated over small changes in extent of

reaction, ~ 5 percent, at extents of reaction greater than 40 percent).

The activation energies were determined using the factor- jump method of

563-81
thermogravimetry, which avoids the need to specify a form for the dependence of the rate of weight loss on the extent of reaction and also

determines the activation of energy without any correlation with the

preexponential factor of the Arrhenius equation. Such activation energies

are expected to be relatively unbiased.

Table 1

Effect of Pressure on Kinetic Parmeters of Thermally

Degrading Polyethylene

pressure, mm Hg of N 2 + volatiles

•v 0.005 8 800

E (kcal/mole) 65.4 ± 0.5 64.8 ± 0.3 62.6 ± 0.5

temperature

3

, °C 425 445 460

bubbles? yes no no

order of reaction 1.5 ± 0.5 0.8 ± 0.3 0.7 ± 0.3

a For roughly equal rates of weight loss from approximately the same size of sample at roughly the same extent of degradation at the specified pressure.

The apparent overall activation energy and the apparent order of reaction

decrease as the pressure increases (table 1), which suggests that simple

evaporation [3] is a significant factor. Evaporation of liquid alkanes

such as C 36 H 74 is easily shown experimentally to be of zero order,

depending only on the available surface area, when the vapor pressure of

the pure liquid is below the external pressure. When the vapor pressure

is equal to the external pressure, normal boiling occurs in that the

temperature of the liquid depends on the applied pressure and ideally

cannot be increased by increasing the heating rate. Such increases

provide more vapor, and when the quiescent surface area is not sufficient

to allow the required amount of vapor to form, more surface area is

provided through the creation of bubbles.

In vacuum conditions, unsteadiness in the sample weight is observed and

has been attributed to bursting bubbles. No shocks to the balance are observed at overall pressures of 8 and 800 mm Hg of N 2

. The calculations

show that normal boiling ceases at ~ C 29 for 8 mm Hg and 445 °C, at ~ C 8 for 800 mm Hg and 460 °C, and at ~ C 85 for 0.005 mm Hg and 425 °C (see

table 1) for the hypothetical mixture of hydrocarbons. Thus the vacuum

case requires that molecules up to C 85 be forced rapidly out of the

liquid. The slowness of diffusion for the largest of these molecules

(C30 to C 85 were not under boiling conditions at 8 mm Hg and 445 °C) to

the quiescent surface must require the formation of "local surface" in

the form of bubbles, so that they may be volatilized. Because most

nucleation is heterogeneous, these bubbles would form on the wall of the

sample cup. The smaller molecules will have very large vapor pressures

at the temperatures of interest and are so unstable with respect to
boiling that they are able to enter even very small bubbles. Thus the

small molecules will act as a dissolved permanent gas. In this sense,

the smaller molecules "nucleate" the bubbles which then accept the

larger molecules as the bubble size increases.

The temperatures in table 1 correspond to degradation rates of ~ 1:4:10

when the observed [1] activation energy of 65.4 kcal/mole is applied.

These temperatures are for approximately equivalent rates of weight- loss

under the pressures specified in table 1. Since the weight loss is

independent of whether methylene units are joined or not, this means

that, for equal overall rates of weight loss, samples which are degrading

faster because of their higher temperature are volatilizing shorter

molecules. In particular, the average molecular weights in the vapor

phase are 1:1/4:1/10 = 1:0.25:0.1 at these temperatures.

The calculated average number of carbon atoms per volatilizing molecule

is 49:20:9 for the three cases considered. These values lie in the

ratio 1:0.41:0.18. The last two are in approximately the correct ratio

to each other. The first, for the near vacuum case, is somewhat too low,

as expected because the tail obviously should include molecules longer

than C 10 o } but these molecules were not included in the calculations

because their Antoine coefficients are not available. Also, the total

pressure was probably not exactly the 0.005 mm Hg assumed for the vacuum

case and the upper limit of boiling molecules is very sensitive to the

total pressure in this region. A lower pressure would give a higher

average molecular weight and a greater range of boiling molecules.

The important aspect is to minimize the tail representing "normal evaporation" as opposed to "normal boiling", and the calculations show that

the appropriate conditions are that the pressure should be as low as possible. The temperature has less effect in reducing the proportion of

weight loss by evaporation but has a large effect on the size of molecules

volatilized and hence on the propensity for explosive bubble formation.

The results also indicate the extent to which the assumption of a sharp

cut-off in the size of molecules volatilized is realistic. The largest

molecule evaporating during degradation in vacuum was assumed to have ~ 70 carbon atoms in the Wall-Simha treatment [4,5]. Suehiro and

O'Shima [6] estimated an upper limit of ~ 26 carbon atoms for evaporation

in an inert atmosphere at 420 °C. This upper limit is indeed dependent

on the imposed pressure and is really a distribution. The cut-off is

sharpest at very low pressures, and changes markedly with temperature.

Also, as Wall et al. remarked [4], it may be expected to vary with

extent of degradation. The dependence on temperature and degradation

probably explains much of the discrepancy in degradation products reported

for polyethylene.

[1] Dickens, B. Thermochim. Acta 55: 217; 1982.

[2] Dickens, B. J. Poly. Sci. 20: 1065; 1982.

[3] Carman, P. C. Trans. Faraday Soc. 44: 529; 1948.

[4] Wall, L. A.; Madorsky, S. L. ; Brown, D. W. ; Simha, R. J. Am. Chem.

Soc. 76: 3430; 1954.

563-83
[5] Simha, R. ; Wall, L. A. J. Poly. Sci. 6: 39; 1951.

[6] Suehiro, T. ; O'Shima, E. Kobunshi Ronbunshu 34: 241; 1977.

Thermogravimetric Studies of Polymer Degradation

Subtask 4 of Task 12138

B. Dickens

Thermogravimetry is often and widely used to study polymers because it can be applied to specimens in any condensed form. In a continuing

series of investigations, we have used the highly automated factor- jump

method of thermogravimetry, developed at NBS, to study the thermal

degradation of polyisobutylene (PIBu).

The overall activation energy, E , of the thermal degradation of PIBu

3

has been measured to be 49.2 ±0.3 kcal/mole (207 ± 1 kJ/mole) over the

range 365 to 405 °C in N2 at 800 mm Hg pressure and flowing at 4 mm/s over the sample. This is consistent with some values reported for

thermal degradation in vacuum and in solution. In 5 mm Hg, an apparent

activation energy of 52.1 ±0.5 kcal/mole (218 ± 2 kJ/mole) was found

and, in vacuum, a value of 57 ± 3 kcal/mole (238 ± 13 kJ/mole). Troublesome bubbling made the vacuum values difficult to measure.

Substitution of reasonable values for the activation energies of initiation, E. , and termination, E. , and the activation energy, E , for vacuum

L a degradation in the eguation E

fl = E^/2 + E d

E t/2, yields an activation

energy E d = 20 kcal/mole for the unzipping reaction. This equation

presupposes a degradation mechanism of random initiation, unzipping, and

biomolecular termination. Substitution of reasonable values of AH, the

heat of polymerization, in the definition AE = Ep-E

d suggests that the

activation energy of polymerization reaction at 375 °C is approximately

7 kcal/mole.

Variable Heating Rate Thermogravimetry

Subtask 5 of Task 12138

J. H. Flynn

The prediction of the lifetime of a polymer by extrapolation from weightloss data requires a thorough analysis of the degradation kinetics both

in the initial phases and over a wide temperature range. Techniques

have been developed in which entire kinetic spectra are compared among

experiments performed at heating rates from 6 °/min to 9 °/day. Simple

methods of plotting data from these techniques have been used for diagnosing

shifts in reaction mechanism, uncoupling of competing processes, and testing

the validity of kinetic models.

Considerable weight-loss in vacuum, nitrogen, or air is found to occur below 200 °C when toluene-2, 4-di isocyanate (TDI) and diphenyl methane4,4 1 -diisocyanate (MDI), polyether and polyester soft segment, 1,4-

butanediol polyurethanes are heated at very slow rates. Weight- loss

563-84
in vacuum is punctuated with bursts of volatiles as the internal pressure

of the dissociated di isocyanate builds up more rapidly than it can dissipate by diffusion. TDI polyurethanes degrade at lower temperatures

and with lower activiation energies than do MDI polymers due to their

faster diffusivity and greater volatility. These factors suggest that

techniques may be developed for the direct recovery and reuse of di isocyanates from polyurethane wastes.

Photolytic and Thermal Degradation of Poly (Methyl Methacrylate ) Subtask 6 of Task 12138

B. Dickens

A study on degradation in solar cover plate materials is being carried

out in collaboration with D. Waksman and J. W. Martin of the NBS Center

for Building Technology. PMMA was selected as an appropriate material

because it is inexpensive, relatively resistant to weathering, and noncrystalline (and therefore has no complications from preferred orientation).

Approximately 1 in. square specimens of 1/16 in. thick plates of UV-absorber

free PMMA were exposed to five different temperatures and four levels of xenon arc radiation filtered through borosilicate glass. Nearly all published studies on photodegradation of PMMA used 254 nm radiation, which is

readily absorbed by the ester groups of PMMA. This study used only wavelengths greater than 300 nm to simulate degradation by solar radiation.

Mechanical properties are well known to be influenced by changes in

molecular weight. In particular, reduction in the molecular weight of

PMMA causes embrittlement (once a critical level is reached) and lowering

of the glass transition temperature. Molecular weight distributions

were therefore determined for more than 250 specimens (including triplicates and controls) using gel permeation chromatography. Computer

programs which allow data collection and data processing with considerable

precision were written by J. D. Barnes and F. L. McCrackin of the Polymer

Science and Standards Division.

In addition to analysing the effect of the degradation on the whole

specimen, we measured the molecular weight distribution as a function of

depth along the irradiation direction. Microtoming was unsatisfactory

because the material was too brittle. Milling was a satisfactory way of

providing more than 20 slices, provided the specimen was large enough.

Because of the small size of most specimens, we first sawed selected

specimens into up to 5 slices with a diamond wafer saw. GPC analysis of

these slices has shown approximately equal degradation on the front and

back sides of the PMMA sheets and considerably less in the center, probably

due to oxygen starvation there. Quantitative analysis of chain scissions in

terms of degradation temperature and incident flux is now beginning.

UV spectra are being used to investigate chromophores which are formed

and consumed during the degradation. Shifts in the edges of the UV

absorption bands in PMMA are being studied using difference spectra on whole and on sliced specimens. The bands appear to correlate with the

extents of thermal and photolytic degradation.

563-85
Water analysis using FTIR to study the 5263 cm

-1 IR absorption of a water combination band has shown that PMMA is extremely sensitive to the

humidity of the atmosphere and typically contains 1 to 2 percent water.

The effects of such levels of water on the degradation mechanism through

plasticization of the PMMA will be studied next.

Fluorescence Measurement of Antioxidant Migration from Low Density

Polyethylene into 1-Propanol

Subtask 7 of Task 12138

F. W. Wang and B. F. Howell

Although the fluorescence technique has been used to determine additive

concentrations in polymers [1,2], to our knowledge, there has been no report on the use of this technique to measure the diffusion of an additive from a polymer matrix into an extracting solvent. To carry out

successfully a diffusion measurement by the fluorescence technique, one must take precautions to exclude oxygen from the extracting solvent

since oxygen quenches the fluorescence of the additive and, in some cases, contributes to its photodegradation. We describe here how oxygen

exclusion was incorporated into a procedure to measure the diffusion of

an additive from a polymer matrix into an extracting solvent. We also

describe the application of this procedure to the diffusion of an amine

antioxidant, N ,

N

1 -diphenyl-p-phenylene-diamine (DPPD), from low-density

polyethylene (LDPE) into 1-propanol and we give a preliminary value for

the diffusion coefficient of DPPD in LDPE under the experimental conditions

described below.

Experimental

DPPD- LDPE Films

DPPD was purified by recrystallization from toluene. NBS-SRM 1476, a low-density polyethylene whole polymer, was washed under a nitrogen

atmosphere, first with toluene at 110 °C, and then with heptane at 22 °C.

The DPPD-LDPE powder, in which 0.05 wt. % of DPPD was uniformly distributed,

was pressed in air into pellets with an IR pellet press. These pellets were placed in teflon molds, fused under a nitrogen atmosphere, and then

quenched with dry ice. The films thus obtained were approximately 0.355 mm thick; they were trimmed with an arch punch to form discs 0.95 cm in

diameter. Two films were a combined mass of 0.49 ± 0.006 g were extracted

during each diffusion coefficient determination.

Extraction Procedure

Ten ml of 1-propanol were added to a weighed, specially constructed

extraction vessel (fig. 1). A side arm of the vessel (A in fig. 1) was attached with wax to a high vacuum line. Solvent in chamber D was degassed inside the vessel by repeated freezing, evacuation and thawing.

Partial loosening of the stopcock (E in fig. 1) opened the vessel to the vacuum line while sealing it from the atmosphere. By means of the vacuum line, oxygenfree, purified nitrogen, at a pressure slightly

greater than one atmosphere, was introduced into the vessel. Then, the

vessel stopcock was removed. Nitrogen gas flowed through the vessel

563-86
while plastic tubes were first inserted; then DPPD-LDPE films were introduced into the vessel. The plastic tubes were designed to prevent

transfer of stopcock grease into the vessel, and to guide the films into

the empty vessel chamber (C in fig. 1). After film introduction, the

stopcock was quickly replaced, and the 1 -propanol allowed to thaw The

nitrogen-filled vessel was removed from the vacuum line with the stopcock

closed, and the system equilibrated to 22 °C.

At the beginning of an extraction experiment, 1 -propanol was introduced

into the chamber containing the films by tipping the vessel. The fluorescence intensity of the solution in cell B was observed to increase with

time. The intensity was measured at suitable time intervals unti no further increase was noted, usually after a week. Between mease reme ;;t n, the vessel was placed in a constant temperature bath at 22 °C, and the

alcohol solution was stirred with a magnetic stirrer. To guard against

stopcock oxygen leakage, nitrogen was passed through needles piercing a serum cap covering the open arm (A in fig. 1) above the stopcock

After completion of the 22 °C experiments, control experiments were

performed, which established that no additional DPPD was extractea when

the system temperature was increased to 60 °C.

Results and Conclusion

To evaluate the diffusion coefficient D from measurements of the increasing fluorescence of the 1-propanol solution, fluorescence intensity was plotted as a function of square root of extraction time. For these

plots, there was an initial linear increase in fluorescence intensity

followed by approach to a horizontal asymptote. From these plots, we obtained the initial slope, and the asymptotic fluorescence inter. sity,

F^. Use of the relation [3]

M

t

/M

<» = 4/7t1/2 (Dt/£

2

) 1/2

(for which £ is the thickness of polymer film undergoing extraction, t is the time in seconds, and M. and are the amounts of diffusing

substance present in the extracting solvent at times t and at equii in

respectively) allowed calculation of D if the ratio M^/M^ was replaced

by the ratio of sample fluorescence intensity at time t, F^, to sample

fluorescence intensity after extraction was complete, F . we verified

that in the concentration range of these experiments, fluorescence

intensity is linearly related to concentration.

Five independent measurements give a value for D of 8.5 x 10-lo cm2 /s

with a standard deviation of 0.6 x 10“10 cm2 /s for migration of DPPD

through LDPE when extracted with a 1-propanol at 22 °C.

[1] Kirkbright, G. ; Narayanaswamy , R. ; West, T. Anal. Chim. Acta 52:

237; 1970.

[2] Crompton, T. Additive migration from plastics into food. Pergamon

Press: New York; 1979, p. 47.

[3] Crank, J. Mathematics of diffusion. Oxford Press: London; 1956,

p. 248.

563-87
Diffusion of Small Molecules in Polymers

Subtask 8 of Task 12138

S. S. Chang, J. R. Maurey, and W. J. Pummer

In FY82, besides finishing up the experiments with the migration of

n-C 18 H 38 , n-C 32 H 66 and 3,5-di-t-butyl-4-hydroxytolune (BHT) from linear

and branched polyethylenes , isotactic polypropylene, and (ethylene-vinyl

acetate) copolymer into various solvents (NBSIR 82-2472), the following

areas of research were undertaken.

Migration of BHT from Impact Modified Polystyrene (IMPS). The rubbery

IMPS swells and loses dimensional rigidity by the action of many commonly

used fat or oil simulants. Therefore, in choosing a simulant, one should

consider the degree of swelling or the retention of the dimensional rigidity. The study also indicated the somewhat limited utility of IMPS in

contact with certain types of food.

Migration of Styrene Monomer from Polystyrene. The migration of carbon-14

labeled styrene monomer from so-called "crystal styrene" occurs in the

glassy state below the T . The kinetics of diffusion in the glassy

y

state sometimes follows the Case II behavior, such that the initial

amount migrated is linearly proportional to time, t, rather than to t

1 2 as in the normal. Fickian behavior. The diffusion coefficient in the

glassy state is generally several orders of magnitude less than that in

the rubbery state.

Absorption of small molecules from Migrant Solutions by Polymers. The

migration of small molecules across the polymer/solvent interface may

also be studied by the absorption of the migrant by a polymer from the

migrant solution. If the absorption is to be monitored by the decrease

of the migrant concentration in the solution, then the range of the partition coefficient and the solubility are required to be within certain narrow limits, in order to generate changes that are large enough for a meaningful kinetic study. We have already performed such a study in the case of absorption of n-C 18 H 38 by polyethylenes from a 50 percent ethanol

solution. Currently the absorption of n-C 32 H 66 by polyethylenes from an ethanol solution is under study.

Solubilities of n- Alkanes in Polyolefins and in Various Solvents

Subtask 9 of Task 12138

S. S. Chang and J. R. Maurey

Solubilities of digomers of linear polyethylene, such as n-C 18 H38 and

n-C 32 H 66 , in various solvents, as well as in polyolefins, have been

determined. The ratios of solubilities in the solvent versus that in

the polymer agree well with the partition coefficients as observed by

both extraction and absorption experiments reaching equilibrium distribution.

The solubilities of n-paraffins in n-heptane behave rather ideally. In

the ideal case, the solubility as a function of temperature may be

predicted from the heat of fusion and the melting points of the solute.

563-88
Long chain n-paraffins exist in a rotator phase just a few degrees below

the melting point. Solubility measurements on the low temperature phase

lead to a hypothetical melting point slightly above the rotator phase

transition temperature.

Measurements of Relative Diffusion Constants in Polymers

Subtask 10 of Task 12138

G. A. Senich

Relative diffusion constants for oligomers, stabilizers, and other low

molecular weight compounds in polymers have been obtained by inverse

phase gas chromatography (IGC) experiments. This method of polymer

analysis provides a convenient way of studying the physical chemistry of

interactions occuring between polymers and volatile organic materials or

probes. The methodology is very similar to conventional gas chromatography,

the principle difference being that a polymer of interest replaces the

typical stationary phases used to sorb the vapor-phase probes. The

experiment involves injecting the probe and an inert marker into a flowing carrier gas stream which propels the substances through a column

containing the polymer, coated on an inert support packed within the

column. The time lag between injection and elution of the vapor peak

and its width or standard deviation characterize the polymer-probe

interactions, which are strongly influenced by the carrier gas flow

velocity. The steady-state probe distribution reached between vapor and

polymer phases at low flow rates allows polymer-probe thermodynamics to

be studied. A steady-state distribution is not reached at high flow

rates where the kinetics of polymer-probe interactions are accessible

and the probe diffusivity in the polymer can be obtained as described below.

Chromatographic peak broadening is commonly quantified by the height

equivalent to a theoretical plate, which can be calculated from the

standard deviation and, ideally, is proportional to the carrier gas flow

velocity at high velocities. This constant of proportionality, C, is

related to the diffusivity of the probe in the polymer, D, by the following

expression:

D = 2d

2 k/[3C(l + k)

2

] = Yk/[C(1 + k)

2

]

where d is the thickness of the polymer layer and k is the column capacity

factor derived from the time lag. If C and k are determined by IGC

experiments and d is known from the geometry of the polymer in the column1; the polymer-probe diffusion coefficient can be obtained from the equation.

Several problems have been identified in determining the diffusivity in

this manner. The equation applies only to peak spreading in localized areas

of the column, although the average velocity is often used in its application.

Gas phase diffusion can also contribute to peak spreading and, in turn, to

the C value found at high carrier flow rates. In addition, any calculation

of D is very sensitive to the distance over which diffusion occurs, d.

The value of d used in the equation can vary widely, depending on whether the

polymer ts distributed as a thin, uniform film or in much thicker regions,

although previous studies [1,2] have indicated that the latter geometry

is favored. These complications make absolute diffusivities difficult to

determine by IGC, however, if several probes are studied in the same column,

563-89
the diffusivity of one probe in the polymer can be compared to that of

another irrespective of the method of calculating the absolute diffusivity.

Such IGC experiments have been conducted; the C and k values for selected

alkane probes are given in the table below. This information can be

used to obtain relative di ffusi vi ties by splitting the equation into two

terms: the first describing the polymer geometry only and the second

characterizing the polymer-probe interactions. The first term is constant

in all determinations with a particular column and is abbreviated as Y.

T is form of the equation was used to determine the probe diffusivity

values given in column four of the table. By selecting one of the

probes as a reference, in this case octadecane, the diffusivity of a probe in the polymer relative to the diffusivity of the reference can be

obtained from a ratio of the respective results, also given in the

table. An absolute diffusion constant for each probe in the polymer can

be obtained from the relative diffusivity values if an absolute diffusion

coefficient for any of the probes in that polymer exists. Using the

previous value of 2.4 x 10 -7 cm2 /s for octadecane in HPDE [2], the

absolute diffusivities indicated can be obtained by multiplying the

relative diffusion coefficients by this factor.

Relative Diffusivity of Alkanes in HDPE at 150 °C

Probe a C(ms) k ^Probe D Probe/D

C 18 D(10 7 cm2 /s)

^18 21.9 119. 0.38 Y 1 . 2.4

Cl6 7.8 60.9 2.05 Y 5.4 13.

MeC 15 8.7 49.0 2.25 Y 6.0 14.

Me 7 C 9 18. 12.8 3.74 Y 9.9 24.

^13 12. 12.1 5.74 Y 15.2 36.

C 18 = octadecane; C 16 = hexadecane; MeC 15 = 2-methylpentadecane;

Me 7 C 9 = 2,2,4,4,6,8,8-heptamethylnonane; C 13 = tridecane.

Relative and absolute diffusion coefficients can be utilized in a large

number of industrial applications, such as in modeling the controlled

release of bioactive substances, estimating the amounts of oligomers,

plasticizers, and antioxidants migrating or leached from polymers over

time, and designing membrane separation processes.

[1] Senich, G. A. CHEMTECH 11: 360; 1981.

[2] Senich, G. A. Polymer Preprints, 22: 343; 1981.

Measurement of Antioxidant Diffusion by Microfl uorimetry

Subtask 11 of Task 12138

F. W. Wang and B. F. Howell

The diffusion of the antioxidant N,N'-0-dinaphthyl-p-phenylene-diamine

(DNPD) in branched polyethylene (PE) SRM 1476 is being measured by

microfluorimetry according to the procedure briefly described as follows.

563-90
Two thin rectangloids of PE, one of which contains 0.002 percent w/w of

DNPD, are placed side by side in a close fitting Teflon frame, with the

thin sides adjacent and in contact. The combination is sandwiched

between two pieces of microscope cover glass, compressed with a spring,

and heated in an evacuated chamber. After melting, followed by quenching,

the DNPD concentration approximates a step function which broadens in

time with diffusion at a specified temperature. Concentration profiles

are measured with a microfluorimeter to yield the diffusion coefficient

D of DNPD in PE.

Experiments at 70 °C led to a reasonable value of D for DNPD in PE.

However, because of the limited solubility of DNPD in PE, aggregation of

DNPD often took place in places corresponding to the plateau region of

the concentration profile. To overcome this difficulty, we have (1) re- duced the concentration of DNPD, (2) made certain that the DNPD-contai ning

PE film has uniform antioxidant distribution, and (3) modified the film

fusion procedure so as to produce a film of uniform thickness. We

anticipate that more accurate values of D can be obtained because of

these procedural improvements. If this is not the case, we plan to use

a polymer in which DNPD is more soluble than it is in PE.

Measurement of Translational Diffusion of Polymers by Fluorescence

Photobleaching Recovery Technique

Subtask 12 of Task 12138

F. W. Wang and W. H. Grant

The diffusion coeffcient of chain molecules is a dynamical parameter

which should provide a test of both scaling [1] and reptation [2] concepts

proposed by de Gennes. Recently Hervet and co-workers [3] used the

forced Rayleigh scattering technique to measure the diffusion coefficient

(D) of polystyrene chains in benzene. They found that in the semi dilute

regime where the chains overlap, D decreases with polymer concentration,

c, as c 1,7 - °*i

,

in agreement with scaling law predictions. However,

they pointed out that more experiments are necessary to check the molecular

weight dependence of the diffusion coefficient.

In collaboration with Professor En-Shinn Wu of the University of Maryland

(Baltimore County), we have initiated a project to measure by the fluorescence

photobleaching recovery (FPR) technique the diffusion of chain molecules

in the semi dilute regime. In the FPR technique, one uses high intensity

illumination to deplete by photobleaching the observed volume element of

chromophore-labeled chain molecules. After the bleaching pulse, the

diffusion of unbleached chromophore-labeled chain molecules into the

bleached volume element is observed with low intensity illumination.

From the time constant for the recovery of the original fluorescence

intensity, the diffusion coefficient can be obtained. The FPR technique

can be used to measure diffusion coefficients in the range 10"11 to

10-6 cm2 /s [4].

We have synthesized a chromophore-labeled polystyrene of narrow molecular

weight distribution and measured the diffusion coefficients of this polymer

in solutions of unlabeled polystyrene polymers. These experiments showed

that the labeled polymer has the appropriate type and extent of labeling

563-91
for the FPR technique. However, we were unable to obtain accurate

diffusion coefficients because the geometry of the bleached volume

element was not adequately controlled. To overcome this difficulty, we have designed and tested a three-compartment cell which has an identical

light path for all the compartments. With this cell, the diffusion

coefficients of the samples in two compartments can be precisely measured

relative, to the diffusion coeffcient of a standard sample in the third

compartment. The absolute diffusion coefficients can then be determined

once the absolute diffusion coefficient of the standard sample is determined by an independent method. This novel cell will be used to measure

the diffusion coefficients of this and other similarly prepared polymers

to check the molecular weight dependence of the diffusion coefficient in

the semi dilute regime.

[1] de Gennes, P. G. Macromolecules 9: 594; 1976.

[2] de Gennes, P. G. J. Chem. Phys. 55: 572; 1971.

[3] Hervet, H. ; Leyer, L. ; Rondelez, F. Phys. Rev. Lett. 42: 1681;

1979.

[4] Koppel , D. E. ; Axelrod, D. ; Schlessinger, J. ; Elson, E. L. ; Webb,

W. W. Biophys. J. 16: 1315; 1976.

Partition Coefficient of Vinyl Chloride in Poly (vinyl Chloride ) Subtask 13 of Task 12138

S. S. Chang and W. J. Pummer

Poly(vinyl chloride) (PVC) is one of the most widely used polymers. Its

monomer, vinyl chloride also known as VCM, is a recognized carcinogen.

The allowable level of VCM in the working atmosphere is regulated by

OSHA and EPA. A small amount of VCM is retained by the PVC resin during

the polymerization process. By steam stripping, the amount of the

residual VCM in the resin may be reduced to less than 1 ppm.

Partitioning as the solubility of VCM in PVC has been studied by several

authors at VCM concentrations generally exceeding 10 ppm. As the residual

VCM contents in PVC, especially those being used in contact with food,

may be made much less than 1 ppm. The study of the Henry's law constant

should be extended to the lowest concentrations detectable.

Head-space gas chromatography provides sensitive detection of VCM without

serious interferences. The detection limit is about 50 pg with flameionization detector. With electron-capture detector and nitrous oxide

enhancement, the detection limit may be further lowered.

We have used both manual and automatic injections for the study of the

partition coefficient of VCM in PVC down to a concentration about 20 ppb.

As the lowest concentration, the partition coefficient observed is still

within the order of magnitude as that observed previously for high concen- trations.

563-92
Further refinements are required to determine more precisely the partition

coefficients at low concentrations by reducing the effects of absorption

of VCM by Teflon syringe inserts and teflon septum liner, and by estimating

more quantitatively the amount sampled in automatic injection operation.

563-93
I

563-94

Figure

1

Extraction

vessel:

A,

ground

glass

joint

for

connection

to

vacuum

line;

B,

fluorescence

cuvet;

C,

chamber

into

which

films

are

introduced

prior

to

extraction;

C,

chamber

into

which

films

are

introduced

prior

to

extraction;

D,

chamber

in

which

solvent

is

degassed;

E,

outer

part

of

removable

stopcock.
MICROSTRUCTURE AND PERFORMANCE OF DIELECTRIC PLASTICS

Task 12139

NBS research in the electrical properties of polymers encompases a broad

range of generic applications from insulating materials with low loss to

electronically conducting polymers. Trends in dielectric applications

of polymers include higher working voltages in transmission lines to

conserve energy and materials, save space, and reduce weight. Among the

potential applications for the recently discovered conducting polymers

are light weight solid state batteries, electrochemical sensors, and

energy conversion. Also included in electrical properties are the

piezoelectric and pyroelectric response of polymers which have led to new types of transducers and new measurements. The goal of the task on electrical properties is to carry out long range research to provide the

basis for new or improved measurements and provide concepts and data

regarding the performance of polymers in high payoff electrical applications.

Data, recommendations, and basic scientific concepts resulting from this

work go directly to funding organizations through written reports, to

manufacturers and users through research associates who work with us,

personal communication, laboratory visits, and publication in archival

journals.

The study of electrical conduction of organic polymers is a major new frontier in solid state physics. Most current research involves an empirical search for improved dopant-polymer combinations from a bewildering

array of compounds. Chemical structure-electrical property correlations

are not yet evident. The key need is for a better knowledge of the

molecular packing, dopant locations, chemical changes with doping,

molecular orientation, and charge carrier pathways to form a basis for

modeling and predicting electrical properties. This work is ideally

suited to NBS because it involves long range research on improved measurements, standards, test methods, and scientific concepts. Good progress

has been made in an appreciable initial effort on electronic conduction.

Applications of polarized polymers as pyro- and piezoelectric transducers

are rapidly growing. Transducer manufacturers as well as private and

Government transducer users (DOD, EPA, HHS) need reliable basic information

connecting polymer structure and polymer performance to the design of

improved transducers. This work provides the scientific basis for

transducer material and device manufacturers to design and develop

commercial polymer transducers for use in a wide range of generic applications.

Important scientific opportunities of this work include breakthroughs in

understanding the basic factors in electrical failure of polymers and

discovery of novel measurement techniques which are becoming possible

with newly developed polymers. For example, on-going work will show how

polymers interact with electronic and ionic charges and how structure

modification alters piezoelectric and semiconducting properties.

563-95
Fast ion transport in polymers provides a basis for a large and growing

class of important applications including production of chlorine and

caustic from brine, hydrogen production from low-head hydroelectric or ocean thermal energy sources, solid electrolytes for fuel cells and

batteries, gas sensors, materials separation membranes, and electrochemical

devices. NBS work is aimed at characterizing the polymer structures,

measuring their properties, and relating the structures and properties

to provide a scientific basis for predicting specifically and transport

mechanisms at the molecular level.

The execution of the task was assisted by Dr. C. Hansen, an industrial

research associate from G.E., Dr. G. Harris, a guest worker from the FDA,

and by a joint project with Bell Laboratories.

Automated Dielectric Measurement

Subtask 1 of Task 12139

F. I. Mopsik

This activity was begun to develop an efficient, rapid measurement

system to characterize dielectric materials. It will allow material

studies that were not previously feasible due either to the excessive

time and equipment required or the lack of accuracy available.

The instrument being developed will record the transient electric charge

response of a dielectric sample to a step change in the applied voltage

in real time. This response will be transformed into the dielectric

constant and loss over the frequency range of 1 mHz to 10 kHz and plotted

by computer.

During FY82 the first version of the system has become operational and

its limits examined. As the electronic circuits were completed last

year, the only work done was the improvement of the generator to remove

its lack of reproducibility at very short times. Improved amplifiers

have improved the setting time behavior by a factor of four.

The major work this year has been to develop the transform techniques

and the operating programs needed to have a fully operational system. A

numerical procedure has been founded and developed that has a basic

accuracy of better than 0.1 percent of full scale and can be carried out over 8 decades in frequency in only 1.5 minutes. In addition, a complete

set of operating programs has been completed so that measurements to

10 4 Hz can now be carried out in less than two hours. A series of

measurements as a function of temperature can be completed in less than

a week.

Initial measurements have shown that the instrument is capable of detecting

a loss peak with a tan 6 as low as 10-4 from a standard capacitor as well as the loss peak in polypropylene at 10 Hz.

An invited talk at the Gordon Conference on Dielectrics on August 3,

1982 is being presented on the measurement scheme as the latest in the

state-of-the-art.

563-96
Dielectric Loss Spectra of Polymers in the Microwave Region

Subtask 2 of Task 12139

A. J. Bur

This work was undertaken as a result of a direct request from the U.S.

Army Civil Engineering Research Laboratory. It consists of a review of

dielectric loss data for polymers at microwave frequencies and an ill uci

dation of the molecular mechanisms which are responsible for microwave

absorption.

A review of the literature reveals that most of the dielectric data for

polymers in the frequency range 100 MHz to 100 GHz has been published in

the past 15 years. The impetus for this work comes from the communications

industry which seeks low loss materials. Well-known low loss dielectrics

such as polyethylene, polypropylene, polytetrafluoroethylene, and polystyrene have been measured by several laboratories. Data for other polymers

are more difficult to obtain and in some cases do not exist. One of the

largest sources of data has been reports from the Massachusetts Institute

of Technology, Laboratory for Insulation Research.

The molecular mechanisms responsible for microwave losses are dipoles

which are part of a short segment of the main polymer chain or a side

chain. A dipole in the amorphous phase is more likely to produce microwave absorption than is one in the crystalline phase.

This work is being assembled as a review and a final report to the Army.

Resistivity Measurements on Ultra-Drawn Poly(vinylidene fluoride) (PVDF)

Films

Subtask 3 of Task 12139

A. J. Bur

This subtask directly supports the optimization of piezoelectric polymers

for applications in industry and Government. It concerns the definition

of PVDF properties prior to poling which, after poling, will yield

highly active transducers with optimum ageing characteristics.

Thick specimens were prepared by molding PVDF pellets in a compression

mold under vacuum. Subsequent preparation steps included annealing or

no annealing and various amounts of mechanical drawing ranging from 4:1

to 7:1 draw ratio at 140 °C.

For resistivity measurements, the samples were fitted with guarded

electrodes in order to eliminate the effect of surface currents. Several

step voltages in the range 75 V to 275 V were applied to each sample and

the current was detected using an electrometer or operational amplifier.

The current at 10 minutes was used to calculate the resistivity.

X-ray measurements were also made on samples having a range of draw

ratios. With these observations we were able to calculate the proportionate amount of a and 0 phase crystals in the samples.

563-97
The results of the resistivity measurements show two effects: first,

the resistivity decreases by a factor of two or foir as the unoriented

samples are oriented to a 4:1 natural draw ratio; second, the resistivity

increases monotonical ly by over a factor of 10 as draw ratio increases

from 4:1 to 7:1. The x-ray measurements show that the resistivity

increases as the p phase content increases which indicates that the p phase content increases with draw ratio.

The data reflect the polarization response of the sample to a step

voltage. The current is interpreted as that due to a dispersion with a long relaxation time whose origin is dipolar orientation and/or ionic

conduction in a Maxwel 1 -Wagner process.

Samples with the highest resistivity are those with the highest draw

ratio and high p phase content. We suggest conductivity in these samples

is minimized because of the presence of the polar p phase crystals which

impede the motion of conducting ions in their neighborhood. These

samples are being considered as candidates for optimum transducer activity

because high poling fields can be used to polarize the samples and

because extremely long relaxation times will inhibit any decrease in

activity.

Conducting Polymers

Subtask 4 of Task 12139

H. P. R. Frederikse, C. K. Chiang, and W. R. Hosier

Polymers in which electrical conduction approaches that of metals is a new area of materials science in which there are many unsolved problems

but the potential applications are enormous. NBS is making measurements

on some of these systems to define the measurement problems for the

purpose of improving measurements and developing test methods as well as developing concepts for the conduction mechanism in these materials.

Most of the polymers of interest are not conductive in the as-polymerized

state but must be modified. The addition of oxidizing or reducing

agents to develop conductivity has been referred to historically as "doping" but this term is probably inappropriate because of the large

quantities of added material and the specific oxidation-reduction reactions

that occur. At NBS, emphasis has been placed on poly-p-phenylene sulfide,

PPS, and polyacetylene, (CH)

x

.

Iodine changes the conductivity of PPS from 10“14 to ^ 10“4 S/m at room temperature, but this conductivity decays with time. Apparently, iodine

only affects the surface of the PPS film in the early stages of the

doping process. For longer periods of time this dopant strongly attacks

the polymer and destroys its conductivity as well as its molecular

structure. AsF 5 higher and more permanent conductivity in PPS as long

as the polymer is kept below 330 K. Measurements between 110 and 330 K

yield reproducible values; plots of In a vs 1/T indicate activation

energies of 0.09 to 0.14 eV. Optical absorption of pure PPS shows a sharp cutoff at 362 nm or 3.43 eV which probably represents the intrinsic

gap between energy bands associated with small 7t-overlap of the sulfur

3p and carbon 2p electronic states.

563-98
Polyacetylene can be made conductive electrochemical ly which is easily

followed by monitoring electrical current and potential. The first

phase of this program is to develop the electrochemical doping and

modification techniques. This is done via collaboration with E. Blubaugh

and W. Yep in Dr. R. Durst 1 s electrochemical group in the Division of

Organic Analytical Chemistry. In this year, we have produced polyacetylene

electrodes on platinum substrates and in freestanding form. Currentvoltage characteristics of these electrodes were measured. For a freestanding (CH)

x electrode in 0.5 M percent LiAsF6 propylene carbonate solution, the positive potential at (CH)

x electrode attracts AsF 6 toward the

(CH)

x film and dopes the film. The doping reaction can be written as

(CH)

X + yx (AsF

6

)" - [CH (AsF

6

) y] x + yx e"

The extra charges were removed at the electrode through the external

circuit. The doping current increased monotonical ly as the applied

potential increased up to 2.0 volts. On the reducing of applied potential,

the electrochemical current showed a peak at 0.4 volt. This suggests

that the dopants are electrochemical ly bound to the polyacetylene. A

similar response was seen in the graphite intercalation. By continuing

to apply a positive potential, we can dope (CH) to a highly conducting

X

state. The electrochemical response of highly doped polyacetylene is

very much like a metal. This electrochemical modification of polyacetylene

requires much longer time 10 h) than that by gas doping (ca. 10 min).

Conducting polymers produced in this manner may have very unique physical

properties.

Since conductivity is rapidly destroyed by oxygen, the oxidation mechanism

of polyacetylene and its kinetic parameters are of interest. Free standing

polyacetylene films have been prepared and oxidized in air and in pure

oxygen gas at room temperature and at higher temperatures. Infrared spectra

of these oxidized samples were measured. An absorption between 3650 and

3200 cm

-1 was not present in pure polyacetylene and is due to the steady

formation of -OH groups. In most cases of hydrocarbon and polymer oxidation, there is a significant proportion of -00H groups (hydro peroxide),

which also absorb in this range. The absorption persisted after the

sample was heated to 200 °C and thus is assigned to hydroxyl groups.

Other indicators of the course of the oxidation are the absorptions at

1725 and 1670 cm

-1

. A general change in the background was observed.

Detailed analysis is in progress.

C 13 NMR spectra were taken of the polyacetylene films oxidized at 50 °C

for 40 h in air. Heating at high temperature first converted (CH)

x films

from cis-to trans-form. New resonances appear at shifts of ^ 58 ppm, ^ 78 ppm, and 197 ppm. Preliminary assignment of these resonances

are: the 58 ppm and 78 ppm resonances are due to sp3 type carbons and

the 197 ppm resonance is due to sp2 type carbons in carbonyl groups.

Detailed consideration of these assignments is also in progress.

The weight increase of polyacetylene due to oxidation was also studied.

A sample exposed to air at room temperature for 153 days may increase in

weight by over 60 percent. The electrical conductivity decreased to the

order of 1 x 10“12 S/m during oxidation.

563-99
Structure and Performance of Piezoelectric Polymers

Subtask 5 of Task 12139

G. T. Davis and M. G. Broadhurst

The objectives of this task are to study the molecular motions, structural

changes, and electrical properties associated with the process whereby

polymers are made piezoelectric. Information gained from these studies

will be used to optimize piezoelectric and pyroelectric response with

respect to both initial activity and long-term stability.

While piezoelectric and pyroelectric activity from polymers is comparable

to that from good ceramic materials, other properties of polymers often

make them the preferred transducer material. Some of the polymer properties

which make them so useful include toughness, flexibility, low density,

broad band response, close acoustic impedance match to water, and ease

of fabrication. Requests for information from other Government agencies

and from industries have remained numerous. Interest in this area of

research continues at a high level, as evidenced by the 16 papers on this topic presented at the American Physical Society meeting in March

1982, numerous review articles in the literature, and commercial advertisements for polymer transducers in trade journals.

The results of an investigation into the structural changes which occur

in a copolymer of vinylidene fluoride and trifluoroethylene (52.8 percent

VDF) upon poling and subsequent depoling at elevated temperatures were

reported in a series of two

effort between personnel of

and the Bell Laboratories,

converted to a single polar

all-trans. Upon heating to

publications. The work was a collaborative

the Polymer Science and Standards Division

An initial mixture of two crystal phases is

phase in which the chain conformation is

85 °C, the polymer chains undergo a gradual

transition to a somewhat disordered (trans gauche) 3 conformation which

has no net polarization. Additional compositions of such copolymers

(65/35, 73/27, and 78/22) have been obtained and their properties are now being studied, again in collaboration with Bell Laboratories and

Dr. Furukawa at the Institute of Physical and Chemical Research, Saitame,

Japan who had been a guest worker at Bell during the previous effort.

These copolymers crystallize almost completely in the all-trans conformation but do undergo a phase change to the nonpolar helical conformation

at temperatures that get closer to the melting point of the copolymer as the VDF content increases. A study of the properties associated with a ferroelectric Curie point of these polymers may help in understanding why

the PVDF homopolymer begins to lose piezoelectric properties at temperatures above 90 °C even though no definite phase changes have been observed

prior to the melting of the polymer.

Polarization and Space Charge Studies

Subtask 6 of Task 12139

A. S. DeReggi , F. I. Mopsik, and A. J. Bur

A measurement method for determining the distribution of space charge or polarization within a dielectric film is now being employed. The method of

imparting a thermal pulse to one surface of the sample and following the

563-100
transient charge or voltage response as the temperature equilibrates was introduced to NBS by a quest worker (Dr. R. E. Collins from Australia).

Recent advances in data acquisition and numerical analysis permits the

determination of up to ten Fourier coefficients of the polarization or charge distribution. Details of the analysis have been submitted to the

Journal of Applied Physics.

The measurement of polarization and space charge distributions in solid

polymers is basic to understanding polymer-charge interactions. In the

ferroelectric polymers, these interactions give rise to nonuniform

polarization distributions across the thickness of film samples. In the

insulating polymers, these interactions are believed to play a key role

in the insulating properties, electrical strength and other performance

and aging properties. Furthermore, charging phenomena are of basic

interest to spacecraft designers concerned with the possibly deleterious

effects of space radiation on the spacecraft-borne instruments.

The method has been applied to the study of PVDF when poled at room temperature. The regions of the film near the surfaces were shown to

require higher poling fields than the bulk of the film and to remain

less poled by approximately 15 percent at fields to 2 MV/cm. When a film was first poled to 2 MV/cm and reverse poled to -1 MV/cm, the

center was reverse poled but the surfaces still retained polarization in

the original direction with nearly zero mean polarization for the entire

sample. A paper on these results has been prepared and has been submitted

to the Journal of Applied Physics for publication.

A study has also been done with Professor Sidney Lang of Ben Gurion

University. PVDF was poled at low fields at room temperature with A1

and Au electrodes to see if work function changes in the electrode

materials would influence the poling behavior. Previous work indicated

that this could be so. A detailed series of measurements showed that

this was not the case but that apparent changes were due to the presence

of a small amount of permanent polarization in the original, nominally

unpolarized film. The strength of this preexisting polarization varied

randomly among samples. Also, the two surfaces of the film were found

not to be equivalent. These results reinforce and amplify our previous

results that the film is intrinsically nonuniform in its poling behavior.

A paper on these results is now in preparation.

Measurements of the polarization distribution in electron-beam charged

PVC have proven interesting in that they have suggested a new and potentially useful method of measuring the electric field inside the foil

during irradiation. During irradiation, the beam- injected charge is

known to give rise to strong electric fields in the polymer. The polymer

is believed to become poled under the action of these strong fields, even though the polymer is below its glass transition temperature of

approximately 70 °C. Becasue PVC is a polar material with a linear

polarization vs field relation, the distribution of polarizat ion is

expected to be proportional to the electric field distribution during

irradiation. It turns out that this polarization is stable in time

while the injected charge is neutralized or leaves the polymer within a period of a week. We believe that the measurement of the polarization

distribution of an electron-beam irradiated PVC sample after it has

563-101
discharged for a week under short-circuit conditions yields the electric

field distribution which existed during irradiation. Thermal pulse

measurements performed so far have shown stable polarization distributions

with the qualitative appearance of the calculated electric field distribution during irradiation. Related measurements on PVC samples subjected

to known applied voltages have shown that the polymer can be poled below

its glass transition, and that the polarizability is of the expected

magnitude based on the measured polarization in the irradiated samples

and the theoretically predicted field. A manuscript describing this is

under preparation.

Spontaneous Polarization in Ferroelectric Polymers

Subtask 7 of Task 12139

A. S. DeReggi , S. C. Roth, G. T. Davis, and M. G. Broadhurst

A method for measuring the pyroelectric response of polymers as a function

of temperature while the temperature is increased linearly with time has

been developed at NBS. The technique provides a rapid means of determining

the temperature at which polarization begins to decay and is being used

to establish the effects of poling variables and polymer morphology on the relative stability of piezoelectric and pyroelectric properties.

Measurements of the sample polarization temperature dependence have been

performed on PVDF and on its copolymer with tetrafluoroethylene (TFE).

In both cases the polarization has been found to go to zero when melting

of the sample is complete, rather than at some transition temperature

distinct from the melting temperature. Measurements such as those

described here must be done with well characterized samples since the

ferroelectric polymers, like other semi crystal 1 ine polymers, may exhibit

relaxation or melting behavior which depend on the prior mechanical and

thermal history. The extended range of temperature over which melting

may occur, and the multiphase nature of PVDF samples also must be considered in making the connection between the sample polarization and the

spontaneous polarization.

The measurements on biaxial ly oriented PVDF poled at 100 °C show a gradual loss of sample polarization starting at 70 °C and extending

throughout the remainder of the semi crystal 1 ine range which finally

melts at approximately 170 °C. There is no evidence of ferroelectric to

nonferroelectric transition as reported by others, and no sign of impending

precipitous polarization decrease of the kind shown by analogous spontaneous magnetization of a ferromagnet near a Curie point. A gradual phase

conversion from a polar to an antipolar phase is being considered as an explanation for the gradual loss of sample polarization. The role of

defect motion in the conversion and of relaxation of orientation is also

being considered as related mechanisms.

Future measurements are planned on the VDF-trifluoroethylene copolymer

at high VDF content. A structural -ferroelectric transition distinct

from melting is observed in this system at a temperature which depends

on composition and possibly on history. Extrapolation of the transition

temperature vs composition data to 100 percent VDF would place the

transition in PVDF in the area of its melting point. Future measurements

563-102
also are planned for poly (vinyl fluoride) which is a semi crystal 1 ine

system with a single crystalline phase, in which transformation to

alternate phases should not exist.

Fabrication of Thick Piezoelectric Polymer Film

Subtask--8 of Task 12139

A. J. Bur, M. G. Broadhurst, and A. K. Tsao

This subtask results from a direct request from the Navy to explore

fabrication of thick piezoelectric polymer film for hydrophone use. Thick film is needed because the voltage response of thin PVDF films is

less than typical ceramic hydrophones. The voltage response is inversely

proportional to capacitance and hence directly proportional to the

thickness of the film. To make the voltage sensitivity of polymers

better than that of ceramics the thickness should be at least 750 pm.

To process and polarize a film this thick requires special equipment and

so far only a couple of European companies have been successful at

producing it. In this work, NBS is developing techniques whereby industrial laboratories in the U.S. can process suitable films.

Ultra-drawn PVDF is material which has been stretched beyond its natural

draw ratio of 4:1. Using a PVDF sample which has been previously stretched

to its natural draw ratio of 4:1, it is possible to obtain draw ratios

of 6.5 or 7.0 to 1.0 by reclamping the sample in the Instron machine and

stretching at 140 °C at a rate of 0.05 in. /min. During the ultra-stretch,

the load increases while the sample dimensions decrease, indicating that

the modulus increases with increasing draw ratio. The ultra-drawn

material is desired because it contains p phase material which poles at

lower fields and has a larger polarization than other phases, it is

highly oriented, and it is able to withstand high poling fields.

Poling these thick samples requires high voltages. For example, to pole

a 0.3 mm thick sample at 2.0 MV/cm, 60 kV are needed. Working at these

voltages, it is necessary to suppress corona and flashover conduction by

carrying out the poling in oil and to construct the sample electrodes so that high electric fields are not present at the edges.

Ten out of fourteen samples with thicknesses ranging from 0.21 mm to

0.53 mm were successfully poled. These samples had pyroelectric coefficients ranging from 2.1 to 4.1 nC/cm2 K and hydrostatic piezoelectric

coefficients ranging from 8.6 to 15.6 pC/N.

Acoustic Sensors

Subtask 9 of Task 12139

A. S. DeReggi and S. C. Roth

Measurements employing piezoelectric PVDF transducers in hydrophones and

biomedical sensors have shown the polymeric transducers have superior

performance characteristics over previously available piezoelectric

ceramic devices in terms of a wide operating bandwidth and negligible

insertion effects. These favorable characteristics stem from the similarity in acoustic impedance between the PVDF and the common transmission

563-103
and test media used in ultrasonics, such as water, oils and, in the case

of biomedical ultrasonics, body tissue. There is currently a growing

interest in polymer transducers in the ultrasonic community in general

and in the biomedical community in particular. The collaboration between

NBS and a guest worker from the Bureau of Radiological Health (BRH) has

continued during the past year. The principal aims of the collaborative

work are the development of polymeric acoustical probes for measuring

the radiation pattern of biomedical transducers and the development of

improved methods of characterizing the performance of existing biomedical

transducers using the new polymeric probes. The knowledge obtainable

with the new polymeric sensors can be used to ensure both the safety and

adequacy of ultrasonic dosage as well as to advance research in ultrasonic

treatment.

A variety of ultrasonic probing hydrophones and hydrophone arrays have

been constructed, all featuring the spotpoled, tensioned membrane design

configuration which was introduced at NBS several years ago. A patent

application which was filed by BRH (November 1980), is still pending,

and NTIS has publicized this patent application among ultrasonic manufacturers who might be interested in its commercialization.

In collaboration with NBS, members of the CNR Institute of Clinical

Physiology at the University of Pisa are evaluating piezoelectric sensors

for the monitoring of cardiac patients. Preliminary clinical data on peripheral pulse signals obtained at Pisa with NBS sensors have been

presented at the Computers in Cardiology Conference in Florence in

September 1981. These data appear to give useful information about

cardiac function, and although this information is complementary to, it

is not necessarily contained in EKGs.

Fast Ion Transport in Solid State Polymers

Subtask 10 of Task 12139

C. K. Chiang, G. T. Davis, A. J. Bur, and A. S. DeReggi

Fast ion transport in solids involves a highly specific interaction

between the ionic species and the matrix resulting in transport which is

orders of magnitude greater than simple diffusion. Alkali halide complexes

with polyethylene oxide show this unique property for cation movement.

With financial support from the Office of Naval Research, personnel

experienced in electrical properties have recently begun a long range

investigation into the relation between the structure and morphology of

such polymers and their ability to transport particular ions. These

types of polymers have potential high payoff applications as solid state

electrolytes for batteries., highly specific electrochemical sensors, and

fuel cell separators.

Evaluation of Cellulose Acetate as a Neutron Dosimeter

Subtask 11 of Task 12139

M. G. Broadhurst, A. J. Bur, and R. B. Schwartz

This problem resulted from a request from the Department of Energy to

evaluate a published report that the electrical resistivity of cellulose

563-104
acetate was sensitive to the amount of neutron radiation which it has

received. If true, this effect could be very useful as a basis for a personal neutron disometer.

Several films of cellulose diacetate and triacetate were irradiated with

a fluence of about 3 x 10 9 of 252 Cf fission neutrons per square centimeter.

We observed decreases in resistivity of at most 10 percent. This,

together with the extreme sensitivity of the method to moisture led to

the conclusion, in contradiction to a published report, that the resistivity of cellulose acetate would not make a useful neutron dosimeter.

This work has been accepted for publication.

Electrical Properties of Window Materials for Space Vehicle Re-entry

Subtask 12 of Task 12139

H. P. R. Frederikse, A. L. Dragoo, A. H. Kahn, and W. R. Hosier

Since February 1982, NBS has been helping the Defense Nuclear Agency

characterize the electric and dielectric properties of high temperature

window materials for microwave radiation. The goal of this undertaking

is to determine experimentally the high temperature conductivity of the

material and to analyze its high frequency dielectric behavior. A prime

candidate for windows is hexagonal Boron Nitride (BN), which is a good

insulator. If the material is pure, it is expected that intrinsic

excitation of electrons will produce a conductivity that can be detected

at temperatures higher than 1000 to 1500 °C. Material considerations

and other factors probably will limit the measurement range to a maximum

of 2500 to 2800 °C. Because BN begins to decompose appreciably at

temperatures above 2000 °C (a saturated nitrogen vapor p g of one atmosphere

is reached at about 2500 °C) measurements must be performed in nitrogen

gas at pressures exceeding p

g

. However, our experiments—as well as those of others on oxides, nitrides, etc. —have shown that the gas has

an appreciable electrical conductivity which acts as a shunt on the

sample resistance. Two techniques have been planned to solve this

problem: (1) a sample geometry with "internal" electrodes such that a direct gas conduction path between the two electrodes is being avoided;

(2) a guard ring technique combined with an operational amplifier.

The required temperatures up to 3000 °C will be achieved in an electrically

heated furnace provided with stacks of tungsten heat shields. Temperatures

are measured by means of a W(+aRe) vs W(+bRe) thermocouple as well as an optical pyrometer.

Initial measurements on a BN-sample (hot pressed TS1251—Union Carbide

Company) with "internal" electrodes (see above) produced reliable results

between 1200 and 2100 K. A plot of log resistance vs 1/T shows a straight

line with a slope corresponding to an intrinsic energy gap of 5.2 eV.

Due to the unusual sample geometry it is difficult to translate resistance,

R, into resistivity, p.

A computer program has been designed to analyze the response to microwave

radiation of a BN window with a high surface temperature and a steep

temperature gradient. The large conductivity of the surface layer gives

563-105
rise to strong reflection. The transmitted radiation varies in an oscillating function depending on the total thickness of the window

material

.

This work is expected to contribute to the solution of the long-standing

problem of interrupted microwave transmission during atmospheric reentry

of rockets.

563-106
Other Activities of the

Polymer Science and Standards Division

Invited Talks

Standardization of Gas Transmission Measurements

Edgewood Arsenal, Edgewood, MD

J. D. Barnes

January 20, 1982

A Computer-Controlled Gas Transmission Measuring Apparatus

40th Annual Technical Conference, San Francisco, CA

J. D. Barnes

May 10, 1982

Standard Reference Materials for Gas Transmission Measurements

18th State of the Art Symposium, American Chemical Society, Washington, DC

J. D. Barnes

June 14, 1982

Bonding at the Polymer/Tooth Surface

6th Annual Meeting of the Society for Biomaterials, Orlando, FL

R. L. Bowen

April 24, 1982

Bonding to Dentin-- At Last a Reality

American Society for Dental Aesthetics, New York, NY

R. L. Bowen

May 5, 1982

Electric-Field Induced Changes in the Phase & Orientation of

Polyvinyl i dene Fluoride Crystals, ILIPAC Macro '82 Conf. , Amherst, MA

M. G. Broadhurst

July 16, 1982

Piezo- and Pyroelectricity in Polymers

The Materials Research Society, Boston, MA

M. G. Broadhurst

November 16, 1981

Piezoelectric Polymers as Potential Soil Stress Gages

Air Force Weapons Laboratory, Albuquerque, NM

M. G. Broadhurst

January 6, 1982

Overview of Piezoelectricity, Pyroelectricity & Ferroelectricity in

Polymers

Workshop on Polymers as Synthetic Metals, Los Alamos, NM

M. G. Broadhurst

April 26, 1982

Gruneisen Equation of State for Polymers

Symposium at Los Alamos National Laboratory, Los Alamos, NM

M. G. Broadhurst

April 29, 1982

563-107
Initiator-Accelerator Systems for Dental Applications

ACS Symposium, Las Vegas, NV

G. M. Brauer

April 1, 1982

Crystallography and Thermodynamics of Calcium Phosphates Related to

Biomaterials, Martin Marietta Laboratories, Baltimore, MD

W. E. Brown

January 19, 1982

Thermodynamics of Hydroxyapatite Surfaces, 6th Inti. Summer Conference

on Chemistry of Solid/Liquid, Interfaces, Dubrovnik, Yugoslavia

W. E. Brown

June 25, 1982

Fabrication and Characterization of Ultra-Drawn Thick PVDF Transducers

IUPAC Macro '82 Conference, Amherst, MA

A. J. Bur

July 16, 1982

A Dental and Medical Materials Program at NBS

Johns Hopkins University, Baltimore, MD

J. M. Cassel

April 13, 1982

Calorimetric Studies & Spontaneous Thermal Effects in Poly(chlorotrifluoroethylene) , 11th North American Thermal Analysis Society

Conference, New Orleans, LA

S. S. Chang

October 21, 1981

Topical Fluoridation & Physico-Chemical Mechanisms of Fluoride

Cariostasis

University of Alabama Dental School, Birmingham, AL

L. C. Chow

November 19, 1981

Crystal Structure of Polytetrafl uoroethylene as a Function of

Temperature & Pressure, IUPAC Macro '82 Conference, Amherst, MA

E. S. Clark

July 13, 1982

Crystal Structure of the Low Temperature Form (Phase II) of

Polytetrafl uoroethylene, American Crystallographic Assn. Spring

Meeti ng

National Bureau of Standards, Washington, DC

E. S. Clark

March 29, 1982

A New Test Method for Determining the Environmental Stress-Crack

Resistance of Ethylene Based Plastics,

ASTM Subcommittee D20.12.03, Toronto, Canada

J. M. Crissman

June 23, 1982

563-108
Field Induced Phase Transitions & Piezoelectricity in Vinylidene

FI uoride

Polymers and Copolymers, IUPAC Macro '82 Conference, Amherst, MA

G. T. Davis

July 16, 1982

% Polarization Distribution in PVF2 as Measured by the Thermal Pulse

Method and Recent Results on the Piezoelectric Retention Characteristics of PVF2 Upon Heating to Melting

Thomas-CSF, Laboratorie Central de Recherches, Orsay, France

A. S. DeReggi

September 14, 1981

High Temperature Measurements of the Pyroelectric Response of PVF 2 Computers in Cardiology Conference, Florence, Italy

A. S. DeReggi

September 23, 1981

Review of NBS Work on Piezoelectric Polymers & Its Relevance to

Ultrasonics

Instituto di Acustica O.M. Corbino, Rome, Italy

A. S. DeReggi

September 28, 1981

Piezoelectric Properties of Synthetic Polymers and Their Applications

University of Pisa, Facota de Ingegneria, Pisa Italy

A. S. DeReggi

September 30, 1981

Measurement of Charge Distribution in Polymer Films

Gordon Research Conference on Polymers, Ventura, CA

A. S. DeReggi

January 11, 1982

Electric Field Distribution in Electron Beam Irradiated PVC

California Institute of Tecnology, Pasadena, CA

A. S. DeReggi

January 12, 1982

Ferroelectric Properties of PVF2 and Copolymers and Their Potential

Uses in Ultrasonics and Biomedicine

Johns Hopkins University, Laurel, MD

A. S. DeReggi

February 10, 1982

High Temperature Measurements of the Pyroelectric Response of PVF 2 American Physical Society Meeting, Dallas, TX

A. S. DeReggi

March 8, 1982

Piezoelectric and Pyroelectric Properties of Synthetic Polymers and

Their Applications in Transducers

Southwest Research Institute, San Antonio, TX

A. S. DeReggi

March 12, 1982

563-109
Real-Time Processing of Data and Subsequent Feedback in ComputerControlled Thermogravimetry

Eastern Analytical Symposium, New York, NY

B. Dickens

November 19, 1981

The U.S. Polymer Industry & the Polymer Science & Standards Division

The Institute of Chemistry, Beijing, China

R. K. Eby

September 30, 1981

Structures and Disorder in the Phases of Polytetrafluoroethylene

The Institute for Chemistry, Beijing, China

R. K. Eby

October 4, 1981

The U.S. Polymer Industry & the Polymer Science & Standards Division

The Institute for Applied Chemistry, Changchun, China

R. K. Eby

October 6, 1981

Structures and Disorder in the Phases of Polytetrafluoroethylene

The Institute for Applied Chemistry, Changchun, China

R. K. Eby

October 7, 1981

Structures and Disorder in the Phases of Polytetrafluoroethylene

Northwest University, Xian, China

R. K. Eby

October 10, 1981

Structures and Disorder in the Phases of Polytetrafluoroethylene

The Institute for Organic Chemistry, Shanghai, China

R. K. Eby

October 11, 1981

The U.S. Polymer Industry & the Polymer Science & Standards Division

Fu Dan University, Shanghai, China

R. K. Eby

October 12, 1981

The Structures and Disorder of the Phases of Polytetrafluoroethylene

Pittsburgh Diffraction Conf. , Cleveland, OH

R. K. Eby

November 5, 1981

The U.S. Polymer Industry & the Polymer Science & Standards Division

Indian Institute of Technology, Delhi, India

R. K. Eby

February 2, 1982

Structures and Disorders in the Phases of PTFE

University of Delhi, Delhi, India

R. K. Eby

February 4, 1982

563-110
The U.S. Polymer Industry & the Polymer Science & Standards Division

National Aeronautical Laboratory, Bangalore, India

R. K. Eby

February 8, 1982

Structures and Disorders in the Phases of PTFE

National Aeronautical Laboratory, Bangalore, India

R. K. Eby

February 8, 1982

Characterization of Polymeric Materials with Emphasis on NDE for

Degradation & Failure

DARPA Workshop on Nondestructive Evaluation of Polymers & PolymerBased Composites, Wrightsville Beach, NC

R. K. Eby

April 28, 1982

Disorders in the Crystal Structures of Homo- & Copolymers of

Polytetrafluoroethylene, IUPAC '82 Macro Conference, Amherst, MA

R. K. Eby

July 13, 1982

Durability of Polymers

DARPA Matls. Res. Council Workshop on Polymer Opportunities,

La Jolla, CA

R. K. Eby

July 23, 1982

The Polymer Science & Standards Division of NBS

Martin Marietta Laboratories, Baltimore, MD

R. K. Eby

September 1982

Overview of the Polymer Science & Standards Division

3M Company, Minneapolis, MN

R. K. Eby, M. G. Broadhurst, G. T. Davis, F. W. Wang, B. M. Fanconi

,

and I. C. Sanchez

September 21, 1982

Overview of the Polymer Science & Standards Division

Xerox Corporation, Toronto, Canada

R. K. Eby, M. G. Broadhurst, G. T. Davis, F. W. Wang, B. M. Fanconi,

and I. C. Sanchez

September 23, 1982

Overview of the Polymer Science & Standards Division

National Research Council, Ottawa, Canada

R. K. Eby, M. G. Broadhurst, G. T. Davis, F. W. Wang, B. M. Fanconi,

and I. C.. Sanchez

September 24, 1982

563-111
Fourier Transform Infrared Spectroscopy of Polymers. Theory &

Appl i cation

Symposium on FTIR Techniques in Plastics Characterization &

Processing, ASTM, Williamsburg, VA

B. M. Fanconi

March 16, 1982

Chain Scission and Mechanical Degradation of Polyethylene

IUPAC Macro '82 Conference, Amherst, MA

B. M. Fanconi

July 14, 1982

Calculations of Defect Structure in Polytetrafluoroethylene

IUPAC Macro '82 Conference, Amherst, MA

B. L. Farmer

July 13, 1982

Role of Thermal Analysis in the Lifetime Prediction of Polymers

Second European Symposium on Thermal Analysis, Aberdeen, Scotland

J. H. Flynn

September 3, 1981

Mettler Award Address

Royal Society of Chemistry, Salford, England

J. H. Flynn

September 7, 1981

Study of Degradation of Polymers by Thermogravimetry

Chemical Society of Vojvodina, Novi Sad, Yugoslavia

J. H. Flynn

September 15, 1981

Comments on Two Enigmas of Condensed Phase Kinetics —The Compensation

Effect and Exact Differential Rate Equations

11th North American Thermal Analysis Society Conference,

New Orleans, LA

J. H. Flynn

October 21, 1981

Study of the Degradation of Polymers by Thermogravimetry

Celanese Research Laboratories, Summit, NJ

J. H. Flynn

January 29, 1982

Kinetics of Polymer Degradation

Polytechnic Institute of New York, Brooklyn, NY

J. H. Flynn

May 18, 1982

Lifetime Prediction from Polymer Degradation Kinetics

IUPAC Macro '82 Conference, Amherst, MA

J. H. Flynn

July 15, 1982

563-112
The Degradation of Polyurethanes by Thermogravimetry

7th International Conference on Thermal Analysis, Kingston, Ontario,

Canada

J. H. Flynn

August 27, 1982

Dynamic Light Scattering from Polymer Solutions

Chemistry Institute of Chinese Academy of Sciences, Beijing, China

C. C. Han

October 4, 1981

Temperature and Molecular Weight Dependence of Polymer Dimensions

Chemistry Institute of Chinese Academy of Sciences, Beijing, China

C. C. Han

October 5, 1981

Polymer Molecular Weight Characterization

Beijing National Institute of Metrology, Beijing, China

C. C. Han

October 7, 1981

Static Light Scattering Theory

Beijing National Institute of Metrology, Beijing, China

C. C. Han

October 8, 1981

Polymer Characterization of Static Light Scattering

Beijing National Institute of Metrology, Beijing, China

C. C. Han

October 9, 1981

Static Light Scattering Instrumentation-I

Beijing National Institute of Metrology, Beijing, China

C. C. Han

October 10, 1981

Static Light Scattering Instrumentation- I

Beijing National Institute of Metrology, Beijing, China

C. C. Han

October 12, 1981

Structure Factor & Second Vi rial Coefficient of Polymer Solution by

Light Scattering, Beijing Natl. Inst, of Metrology, Beijing, China

C. C. Han

October 13, 1981

Small Angle Neutron Scattering from Polymers

Shanghai Provincial Bureau of Metrology & Eastern Regional

Measurement Center, Shanghai, China

C. C. Han

October 16, 1981

563-113
Temperature and Molecular Weight Dependence of Polymer Dimensions

Shanghai Provincial Bureau of Metrology and Eastern Regional

Measurement Center, Shanghai, China

C. C. Han

October 17, 1981

Static and Dynamic Properties of Polymer Solutions

Hongzhou Provincial Bureau of Metrology and Zhe-Jiang University

Hongzhou, China

C. C. Han

October 21, 1981

Temperature and Molecular Weight Dependence of Polymer Dimensions

Guangzhou Provincial Bureau of Metrology and Zhong-Shan University

Guangzhou, China

C. C. Han

October 23, 1981

Light Scattering & SANS from Polymers and Polymer Solutions

Guangzhou Provincial Bureau of Metrology and Zhong-Shan University

Guangzhou, China

C. C. Han

October 24, 1981

Effects of Excluded Volume and Pre-averaging of Oseen-Tensor for Dilute

Polymer Solutions by Dynamic Light Scattering

Dept, of Macromolecular Science, Osaka University, Japan

C. C. Han

November 4, 1981

Small Angle Nuetron Scattering from Polymers

UBE Industry, Osaka, Japan

C. C. Han

November 5, 1981

Dynamic Light Scattering from Dilute Polymer Solutions

Dept, of Polymer Chemistry, Kyoto University, Japan

C. C. Han

November 6, 1981

Dynamic Light Scattering from Dilute Polymer Solutions in the

Intermediate q-region

Dept, of Synthetic Chemistry, Nagoya University, Japan

C. C. Han

November 9, 1981

Small Angle Neutron Scattering from Polymers

Institute of Materials Science, University of Connecticut, Storrs, CT

C. C. Han

December 4, 1981

563-114
Cooperative and Self-Diffusion of Polymers in Semi dilute Solutions

by Dynamic Light Scattering

Dept, of Nuclear Engineering, University of Michigan, Madison, WI

C. C. Han

Aprjl 5, 1982

Dynamic Light Scattering of Polymer Solutions in the Semi dilute Region

Dept, of Chemistry, University of Wisconsin, Madison, WI

C. C. Han

April 7, 1982

Small Angle Neutron Scattering from Polymers

Dept, of Chemistry and Chemical Engineering, Virginia Polytechnic

Institute and State University, Blacksburg, VA

C. C. Han

May 12, 1982

Dynamic Light Scattering from Dilute and Semi dilute Polymer Solutions

Ann Arbor Conference on Quasi elastic Light Scattering Spectra & Their

Interpretations, Ann Arbor, MI

C. C. Han

June 23, 1982

Plastisol Characterization

Office of Naval Research Review on Compliant Coating Drag Reduction,

Naval Research Laboratory, Washington, DC

D. L. Hunston

October 15, 1981

Fundamental Aspects of Adhesion

Workshop on Engineering with Adhesives, East Brunswick, NJ

D. L. Hunston

October 26, 1981

Developing Failure Criteria for the Polymers Used in Structural

Adhesives and Composites

SPI Meeting on Reinforced Plastics/Composites, Washington, DC

D. L. Hunston

January 15, 1982

Mechanics of Adhesive Bond Failure

Center for Professional Advancement, San Mateo, CA

D. L. Hunston

February 10, 1982

Durability and Adhesive Bond Failure

Center for Professional Advancement, San Mateo, CA

D. .L. Hunston

February 10, 1982

Comparison Between Fracture Behavior in Adhesive Bonds & Fibrous

Composites Adhesion Society Meeting, Mobile, AL

D. L. Hunston

February 23, 1982

563-115
Mechanical Properties and Failure Behavior of Toughened Glassy Polymers

Symposium, Civil Engineering Dept., Texas A&M University,

College Station, TX

D. L. Hunston

February 25, 1982

Fracture Behavior of Adhesives and Composite Matrix Resins

General Dynamics Research Laboratories, Ft. Worth, TX

D. L. Hunston

February 26, 1982

Crack Propagation in Rubber-Toughened Epoxy

International Conf. on Deformation, Yield & Fracture, Cambridge, England

D. L. Hunston and A. J. Kinloch

March 31, 1982

General Rheology and Its Applications in Adhesion

Workshop on Adhesion and Adhesives, Kent State University, Kent, OH

D. L. Hunston

June 7, 1982

Flow Fundamentals in Fluid Systems Containing High Molecular Weight

Additives

Symposium on Applied Rheology for the Industrial Chemists, Kent

State Univ. , Kent, OH

D. L. Hunston

June 24, 1982

Fracture Behavior of Brittle Materials

Symposium on Applied Rheology for the Industrial Chemist

Kent State University, Kent, OH

D. L. Hunston

June 25, 1982

Cure Monitoring of Thermosetting Polymers by Ultrasonics

AF-NAVY/DARPA Review on Quantitative NDE, San Diego, CA

D. L. Hunston

August 6, 1982

Characterization of Fracture Behavior of Adhesive Joints

ACS International Symp. on Adhesive Joints, Kansas City, MO

D. L. Hunston

September 15, 1982

Mechanics of Fracture for Adhesive Joints

ACS International Symposium on Adhesive Joints, Kansas City, MO

D. L. Hunston and S. S. Wang

September 15, 1982

Rheology of Cure for Intaglio Printing Inks

ACS Symposium on Chemorheol ogy of Thermosetting Polymers,

Kansas City, MO

D. L. Hunston

September 16, 1982

563-116
The Morphology of Polymers

31st Annual Meeting, Society of Polymer Science of Japan, Tokyo, Japan

F. A. Khoury

May 30, 1982

The Morphology of Polyethylene Crystals Grown from Solution at High

Temperatures, Kyoto University, Kyoto, Japan

F. A. Khoury

June 2, 1982

The Crystallization and Morphology of Polymers

Osaka University, Osaka, Japan

F. A. Khoury

June 3, 1982

The Morphology of Polymer Crystals Grown From Solution

UBE Plastics Laboratory, Hirakata, Japan

F. A. Khoury

June 4, 1982

The Morphology of Polymer Crystals Grown from Solution

Kyushu University, Fukuoka, Japan

F. A. Khoury

June 8, 1982

Dynamic Light Scattering in the Intermediate Momentum Transfer Region

National Institutes of Health, Bethesda, MD

T. P. Lodge

November 19, 1981

Conformation and Dynamics of Polymers in Solution

University of Iowa, Iowa City, IA

T. P. Lodge

January 18, 1982

Conformation and Dynamics of Polymers in Solution

University of Pittsburgh, Pittsburgh, PA

T. P. Lodge

January 20, 1982

Conformation and Dynamics of Polymers in Solution

Carnegi e-Mel on University, Pittsburgh, PA

T. P. Lodge

January 21, 1982

Conformation and Dynamics of Polymers in Solution

University of Georgia, Athens, GA

T. P. Lodge

January 26, 1982

Conformation and Dynamics of Polymers in Solution

Georgia Institute of Technology, Atlanta, GA

T. P. Lodge

January 28, 1982

563-117
Conformation and Dynamics of Polymers in Solution

Purdue University, West Lafayette, IN

T. P. Lodge

February 1, 1982

Conformation and Dynamics of Polymers in Solution

Dartmouth College, Hanover, NH

T. P. Lodge

February 8, 1982

Conformation and Dynamics of Polymers in Solution

University of Illinois, Urbana, IL

T. P. Lodge

February 12, 1982

Conformation and Dynamics of Polymers in Solution

Cornell University, Ithaca, NY

T. P. Lodge

February 17, 1982

Conformation and Dynamics of Polymers in Solution

University of Michigan, Ann Arbor, MI

T. P. Lodge

February 19, 1982

Conformation and Dynamics of Polymers in Solution

University of Minnesota, Minneapolis, MN

T. P. Lodge

February 22, 1982

Conformation and Dynamics of Polymers in Solution

University of California, Berkeley, CA

T. P. Lodge

February 24, 1982

Dynamic Light Scattering in the Intermediate Momentum Transfer Region

APS Meeting, Dallas, TX

T. P. Lodge

March 11, 1982

Oscillatory Flow Birefringence Properties of Polymer Solutions at

High Effective Frequencies

IUPAC Macro '82 Conference, Amherst, MA

T. P. Lodge

July 13, 1982

Non-linear Viscoelastic Behavior of PMMA in Torsion

Centre de Recherches sur les Macromolecules, Strasbourg, France

G. B. McKenna

November 10, 1981

563-118
Le Compartement Viscoelastique du PMMA sous Torsion

L'Ecole d' Applications des Hauts Polymeres

Universite Louis Pasteur, Strasbourg, France

G. B. McKenna

March 10, 1982

On the Small Strain Behavior of Crossl inked Natural Rubber in

Torsion, Extension and Compression

Malaysian Rubber Producers Research Assn. , Brickendonbury , England

G. B. McKenna

April 2, 1982

La Variation due Temps a la Rupture du PMMA et du Polyethylene

L'Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland

G. B. McKenna

April 30, 1982

Deviations from Elasticity Theory of Rubber Behavior at Small Strains

6th European "Network-Group" Mtg. , Strasbourg, France

G. B. McKenna

July 1, 1982

Adsorption on Hydroxyapatite

Chemistry Dept. , Lucknow University, Lucknow, India

D. N. Misra

November 10, 1981

Precision Time Domain Measurements for Audio Frequencies and Below

Gordon Research Conference on Dielectrics, Plymouth, NH

F. I. Mopsik

August 2, 1982

The Role of Dental Materials in Dental Practice

Dept, of Materials Science, Univ. of Virginia, Charlottesville, VA

G. C. Paffenbarger

December 3, 1981

Transport Properties of Highly Drawn Semicrystall ine Polymers

Fiber Society Symp. , Princeton University, Princeton, NJ

A. Peter! in

May 5, 1982

Mechanical Properties & Morphology of Drawn Semi crystal! ine Polymers

IUPAC '82 Meeting, Amherst, MA

A. Peterlin

July 14, 1982

History of Polymer Physics

Gordon Research Conferences, Andover, NH

A. Peterlin

July 20, 1982

563-119
Transport Properties as an Extremely Sensitive Indicator of the

Status of the Amorphous Component in the Elastically and Plastically

Deformed Semi crystal line Polymer

IUPAC Symposium on Polymers, Athens, Greece

A. Peterlin

August 31, 1982

Nature of Fold Surfaces in Lamellar Crystals

European Conference on Polymer Physics, Barcelona, Spain

A. Peterlin

September 22, 1982

Brownian Motion and Polymer Chain Adsorption

Dartmouth College, Hanover, NH

R. Rubin

October 2, 1981

Some Random Walk Questions: Haven't We Been Here Before?

Statistical Physics Seminar, University of Maryland, College Park, MD

R. Rubin

February 16, 1982

Some Far Out Properties of Adsorbed Polymer Chains

University of California, San Diego, La Jolla, CA

R. Rubin

September 1, 1982

Finishing Amalgams

Prevention of Microleakage & Finishing Composite Restorations,

Naval Dental School, Bethesda, MD

N. W. Rupp

September 2, 1981

Esthetic Restorative Materials: Third Generation

Wright-Patterson Air Force Base, Dayton, OH

N. W. Rupp

October 5, 1981

Selection and Use of Dental Materials

Eglin Air Force Base, FL

N. W. Rupp

November 10, 1981

The Selection and Use of Dental Materials

Fresno Madera Dental Foundation, Fresno, CA

N. W. Rupp

December 11, 1981

Research in the Development of Dental Specifications

Georgetown University Dental School, Washington, DC

N. W. Rupp

January 13, 1982

563-120
Proper Manipulation of Dental Materials

Veterans Administration Hospital, Washington, DC

N. W. Rupp

January 14, 1982

•• Dental Cements and Impression Materials

Naval Graduate Dental School, Bethesda, MD

N. W. Rupp

January 28, 1982

Dental Materials for the Fixed Prosthodontist

Veterans Administration Hospital, Washington, DC

N. W. Rupp

February 8, 1982

Dental Research Activities at the National Bureau of Standards

Dental Hygienists' Association, Wilmington, DE

N. W. Rupp

February 16, 1982

Finishing the Amalgam Restoration

Academy of Operative Dentistry, Chicago, IL

N. VI. Rupp

February 18, 1982

Impression and Cementation Materials

Naval Dental School, Bethesda, MD

N. W. Rupp

March 1, 1982

Cementation Materials

Georgetown University Dental School, Washington, DC

N. VI. Rupp

March 4, 1982

Selection and Use of Dental Materials

Lackland Air Force Base, TX

N. VI. Rupp

March 16, 1982

Materials for the Laboratory Technician

Veterans Administration Hospital, Washington, DC

N. W. Rupp

March 23, 1982

Esthetic Restorative Materials

Georgetown University Dental School, Washington, DC

N. W. Rupp

March 25, 1982

Dental Amalgam

Georgetown University Dental School, Washington, DC

N. W. Rupp

April 1, 1982

563-121
The Selection and Use of Restorative Dental Materials: Direct and

Indirect Techniques

Research Study Club of Nebraska, Lincoln, NE

N. W. Rupp

May 21, 1982

Clinical Significance of Pulp Studies and the Biological Responses

to Dental Restorative Procedures and Materials

West Central District Dental Society's 70th Annual Meeting, Brainerd, MN

N. W. Rupp

June 12, 1982

Theory of Phase Equilibria in Polymer Blends

Rutgers University, Piscataway, NJ

I. C. Sanchez

October 9, 1981

Theory of Interfacial Tension in Polymer Mixtures

Princeton University, Princeton, NJ

I. C. Sanchez

December 3, 1981

Theory of Interfacial Tension in Polymer Mixtures

Kodak Research Laboratories, Rochester, NY

I. C. Sanchez

December 9, 1982

Theory of Polymer Blend Phase Behavior

4th Annual Polymer Summer School, Yugoslav Academy of Sciences,

Dubrovnik, Yugoslavia

I. C. Sanchez

April 26, 1982

Thermodynamic Properties of Polymer Blends

Polymer Gordon Research Conference, Col by-Sawyer College,

New London, NH

I. C. Sanchez

July 5, 1982

Thermodynamic Properties of Polymer Blends

IUPAC Macro '82 Conference, Amherst, MA

I. C. Sanchez

July 12, 1982

Theory of Polymer Interfacial Tension

Gordon Research Conference on the Science of Adhesion, New Hampton, NH

I. C. Sanchez

August 23, 1982

Measurement of Polymer-Solvent Diffusivity by Inverse Gas Chromatography

Princeton University, Princeton, NJ

G. A. Senich

April 10, 1982

563-122
What Polymer Chemists Do at the National Bureau of Standards

Howard University, Washington, DC

G. A. Senich

October 7, 1981

Government Careers in Polymer Research at the National Bureau of

Standards

George Washington University, Washington, DC

G. A. Senich

October 21, 1981

Characterization of Polymers: Mechanical Property and Diffusion

Studies

NASA Langley Research Center, Hampton, VA

G. A. Senich

October 26, 1981

Gas Chromatography of Polymers

Chemical Society of Washington, Rockville, MD

G. A. Senich

February 11, 1982

Chromatographic Studies of Diffusion in Polymers

IUPAC Macro '82 Conference, Amherst, MA

G. A. Senich

July 14, 1982

Measurement of Additive Migration from Plastic Food Packaging

ISO Consumer Policy Council, Paris, France

L. E. Smith

April 27, 1981

Models for Migration of Additives from Polyolefins

ASTM Technical Seminar, Williamsburg, VA

L. E. Smith

March 16, 1982

Castability and Fit of Nonprecious Alloys

Eastern Maryland Dental Society, Ocean City, MD

J. A. Tesk

October 2, 1981

Applications of 13 C NMR to the Characterization of Solid Polymers

Virginia Polytechnic Institute, Blacksburg, VA

D. L. VanderHart

October 1, 1981

NMR Studies of Oriented Polymers, LPE and PET

Institute fur Physi kal ische Chemie, University of Mainz, Germany

D. L. VanderHart

March 22, 1982

563-123
13 C NMR Studies in Solid Polymers

University of East Anglia, Norwich, England

D. L. VanderHart

March 24, 1982

NMR Studies of Oriented Polymers, LPE, and PET

University of Leeds, Leeds, England

D. L. VanderHart

March 26, 1982

13 C NMR of Drawn Polymers

University of Bristol, Bristol, England

D. L. VanderHart

March 29, 1982

High Resolution 13 C NMR of Solid Polymers

Annual Chemical Congress of the Royal Soc. of Chemistry,

Birmingham, England

D. L. VanderHart

April 2, 1982

13 C NMR in Oriented Polymers

IUPAC Macro '82 Conference, Amherst, MA

D. L. VanderHart

July 12, 1982

Inferences About Molecular Motion in Solid Polymers from ProtonDecoupled 13 C NMR

NMR Mi ni symposi urn, Monsanto Research Center, St. Louis, MO

D. L. VanderHart

July 20, 1982

NMR in Solid Polymers--An Overview

24th Rocky Mountain Conference, Society for Applied Spectroscopy,

Denver, CO

D. L. VanderHart

August 3, 1982

Measurement of Polymer-Polymer Compatibility by Non-Radiati ve Energy

Transfer Technique

Gordon Research Conference on the Science of Adhesion, New Hampton, NH

F. W. Wang

August 25, 1982

Spectroscopic Study of Amorphous Polyethylene

Johnson & Johnson Co., Milltown, NJ

S. L. Wunder

September 15, 1981

Conformational and Morphological Properties of Polymethylenes

International Mineral and Chemical Co., Terre Haute, IN

S. L. Wunder

November 9, 1981

563-124
Conformational and Morphological Properties of Polymethylenes

Hercules, Wilmington, DE

S. L. Wunder

November 12, 1981

Conformational and Morphological Properties of Polymethylenes

Exxon Research and Engineering Co., Lindberg, NJ

S. L. Wunder

November 17, 1981

Conformational amd Morphological Properties of Polymethylenes

Aerojet Strategic Prop., Sacramento, CA

S. L. Wunder

December 9, 1981

Conformational and Morphological Properties of Polymethylenes

E. I. duPont Co., Wilmington, DE

S. L. Wunder

December 14, 1981

Interatomic Distances in A15 Compounds: Geller vs Pearson Hypotheses

Los Alamos National Laboratory, Los Alamos, NM

R. M. Waterstrat

October 7, 1981

Wear Mechanisms in Dental Composites

American Association of Dental Schools, New Orleans, LA

W. Wu

March 16, 1982

Non-Linear Mechanical Behavior of Polymer Solutions at Various

Concentrations

IUPAC Macro '82 Conference, Amherst, MA

L. J. Zapas

July 15, 1982

Seminars for Staff and Guests

Recent Advances in Polyacetylene Chemistry

Professor Hideki Shirakawa

University of Tsukuba, Tokyo, Japan

August 24, 1981

Mechanisms of Rubber Adhesion and Friction

A. D. Robert

Malaysian Rubber Producers' Research Association

Hertford, England

August 27, 1981

Materials Used in the Lithographic Process

Dr. Larry Thompson

Bell Laboratories, Murray Hill, NJ

September 23, 1981

563-125
Polymer Impregnation and Microstructure of Hardened Cement

Pastes of Various Porosities

Raouf S. Mikhail

Ain Shams University, Cairo, Egypt

September 28, 1981

Disorder in Chain Molecules Observed with Vibrational Spectroscopy

Dr. R. G. Snyder

University of California, Berkeley, CA

November 3, 1981

Scattering Studies of Blends

Professor Richard S. Stein

University of Massachusetts, Amherst, MA

November 19, 1981

On the Role of Liquid Elasticity in Polymer Characterization

and Journal Bearing Lubrication

A. S. Lodge

University of Wisconsin, Madison, WI

November 24, 1981

Clinical-Pathologic Issues in Cardiac Valve Prostheses and Ventricular Assist Devices

Dr. Fred J. Schoen

Peter Brigham and Women's Hospital, Boston, MA

December 10, 1981

Renormalization Calculation of the Structure Factor for Polymers

Professor T. Witten

University of Michigan, Ann Arbor, MI

December 12, 1981

Mechano-vibrational Spectroscopy of Polymers

Professor Shaw Ling Hsu

University of Massachusetts, Amherst, MA

December 14, 1981

Time Temperature Equivalence: After All These Years Can It Be Wrong?

Dr. N. G. McCrum

University of Oxford, Oxford, England

March 16, 1982

Mechanism of Physical Aging in Crystalline Polymers

Dr. N. G. McCrum

University of Oxford, Oxford, England

March 16, 1982

Effect of Thermal Parameters on Compatibility in Porcelain

Veneered Split Metal Rings

Dr. G. E. 0. Widera

University of Illinois, Chicago, IL

March 18, 1982

563-126
Small Angle Neutron Scattering of a Rubber Network

Dr. Robert Ullman

Ford Motor Company, Dearborn, MI

March 29, 1982

Yield- and Fracture of Model Polyethylene Systems

Dr. David C. Bassett

University of Reading, England

March 29, 1982

Crystallization of Polyethylene Copolymers

Dr. David C. Bassett

University of Reading, England

March 30, 1982

Contact Electrification of Polymer Dielectrics & Properties

at High Electric Fields

Professor G. Fuhrmann

University of Kaiserslautern, Germany

April 1, 1982

The True Biodegradation of Implanted Polymers

Dr. David F. Williams

University of Liverpool, England

April 16, 1982

Polymers for Enhanced Oil Recovery

Dr. L. Guy Donaruma

Professor of Chemistry

Polytechnic Inst, of New York, New York, NY

April 21, 1982

Changes in the Elastic Moduli i of Rubber Due to Low Temperature

Crystal 1 ization

Dr. Andrew Stevenson

The Malaysian Rubber Producers' Research Association

Brickendonbury , Hertford, England

April 22, 1982

Conformational and Long Branch Analysis by GPC & Laser Light

Scatteri ng

Dr. Roger S. Porter

University of Massachusetts, Amherst, MA

May 5, 1982

Polymer Liquid Crystals/Biaxial Orientation and Its Development in

Polymer Systems

Professor James L. White

University of Tennessee, Knoxville, TN

May 6, 1982

563-127
Synthesis and Characterization of Model Macromolecules

Professor L. J. Fetters

Institute of Polymer Science

University of Akron, Akron, OH

May 10, 1982

The Synthesis of Hydrophilic Polymers with Nucleic Acid Base Side

Chai ns

Dr. Charles G. Overberger

University of Michigan, Ann Arbor, MI

May 14, 1982

Sliding-Wear Behavior of Dental Restoratives

Dr. William F. Bailey

University of Connecticut, Storrs, CT

May 20, 1982

Influence of Molecular Weight Distribution and Catalysts on the

Crystallization and Orientation of Polyethylene Terephthalate

Dr. H. G. Zachmann

Marti n-Luther-King Platz 6

Hamburg, West Germany

May 21, 1982

Miscibility Behavior of Polyester/Halogenated Polymer Blends

Dr. R. E. Prud'homme

Universite Laval, Quebec, Canada

June 17, 1982

The Oxidation of Stabilized Polypropylenes

Dr. Frank Mayo

Stanford Research Inst. , Stanford, CA

June 18, 1982

Infiltration of Monomers into Hard Tissues

Dr. N. Nakabayashi

Tokyo Medical and Dental University, Tokyo, Japan

June 21, 1982

Kineto Rheology, Chemical Change and Rheological Response

Professor Alex Silberberg

The Weizmann Institute of Science, Rehovot, Israel

July 2, 1982

Fine Structures of Fibers and Films Made from a Liquid Crystal

Dr. M. Horio

Hirakata Plastics Lab., Osaka, Japan

July 7, 1982

Forced Rayleigh Light Scattering of Polymers in Semi-Dilute Solution

& Melts

Madam Liliane Leger

Laboratoire de Physique de la Matiere Condensee

College de France, Cedex, France

July 7, 1982

563-128
Photovoltaic Effect in Ferroelectric Polyvinyl idene Fluoride Film

Professor H. Sasabe

Tokyo University of Agriculture and Tech. , Tokyo, Japan

July 8, 1982

Rheo-Optical Properties of Poly-Alpha-Olefins

H. Kawai

Kyoto University, Kyoto, Japan

July 9, 1982

Qualitative and Quantitative Information on Linear Polyethylene

Fractions as a Function of Molecular Weight

Dr. Ingrid Voigt-Martin

Mainz University, Inst, fur Physikalische, West Germany

July 9, 1982

Microphase Separated Structure of Block Copolymers and

Its Related Properties

Professor Takeji Hashimoto

Kyoto University, Kyoto, Japan

July 9, 1982

Time-Dependent Nonlinear Rheological Properties of Entangled Polymer

Melts and Concentrated Solutions

Professor David Soong

University of California, Berkeley, CA

July 19, 1982

Polarization Switching & Molecular Motion in PVDF & Related Copolymers

Professor A. Odajima

Hokkaido University, Sapporo, Japan

July 20, 1982

Electron Microscopy of Polyvinyl idene Fluoride

Professor K. Sakaoku

University of Tokyo, Tokyo, Japan

July 21, 1982

Luminescent Probe Study on Reactions and Chain Dynamics of Polymers

Professor I. Mita

Faculty of Engineering, Univ. of Tokyo, Tokyo, Japan

July 21, 1982

Gas Liquid Chromatographic Studies on Polymeric Stationary Phases

Professor D. D. Deshpande

Indian Institute of Technology, Bombay, India

July 22, 1982

Thermoluminescence from Irradiated Polymers and Fibers

Dr. T. Sakai

Tokyo Institute of Technology, Tokyo, Japan

July 22, 1982

563-129
X H and 13 C NMR Studies of Solid Polymers

Dr. K. J. Packer

School of Chemical Sci., University of East Anglia, England

July 23, 1982

Mechanical Properties & Morphology of Fiber Glass Reinforced

Polypropylene Composites

Professor A. Misra

Indian Institute of Technology, New Delhi, India

July 23, 1982

Dynamic Behavior of Polyelectrolytes in Solution

Professor Y. Wada

Yamagata University, Yonezawa, Japan

July 26, 1982

Novel Imaging Techniques for Phase Separated Polymers

Professor N. Thomas

University of Massachusetts, Amherst, MA

August 11, 1982

Piezoelectricity in Vinylidene Cyanide-Vinyl Acetate Copolymers

Professor S. Miyata

Tokyo University, Tokyo, Japan

September 8, 1982

Chemical Characterization of Solid Cools via Magic Angle 13 C NMR

Dr. John Havens

Case Western Reserve University, Cleveland, OH

September 15, 1982

NDE for Polymer Composites

Professor R. D. Adams

University of Bristol, Bristol, England

September 22, 1982

Technical and Professional Committee Participation and Leadership

Academy of Operative Dentistry

N. W. Rupp, Councilor

American Academy of Gold Foil Operators

N. W. Rupp, Councilor

American Association for Dental Research/International Association

for Dental Research

R. L. Bowen

Member: Dental Materials Group

Wilmer Souder Award Committee

J. M. Antonucci

Member: Dental Materials Group

G. M. Brauer

Member: Dental Materials Group

563-130
J. M. Cassel

Member: Dental Materials Group

J. E. McKinney

Member: Dental Materials Group

W. Wu

Member: Dental Materials Group

J. A. Tesk

Member: Dental Materials Group

W. E. Brown

Member: Biological Mineralization Research Award Committee

Mineralized Tissue Group, Councilor

American Association of Dental Research/Washington Section

J. A. Tesk

Secretary-Treasurer

American Chemical Society

J. M. Antonucci

Member: Board of Managers

Advertising Editor

G. M. Brauer

Member: Meetings and Expositions Committee

Councilor

D. N. Misra

Chairman: Symposium on Adsorption on and Surface Chemistry

of Hydroxyapatite, Kansas City, MO, Sept. 1982

American Dental Association Special Committee on the Future of

Dentistry

R. L. Bowen

Member: Research Working Group

American Institute of Mining, Metallurgical, and Petroleum Engineers

R. M. Waterstrat

Member: Committee on Alloy Phases

American Institute of Physics

R. K. Eby

Chapter Editor, Physics Handbook

H. P. R. Frederikse

Chapter Editor, Physics Handbook

E. A. Kearsley

Member: Committee for Public Policy

563-131
American National Standards Committee, MD156, Dental Materials,

Instruments, and Equipment

R. L. Bowen

Member: Subcommittee on Biological Evaluation of

Dental Materials, Secretary

G. M. Brauer

Member: Government Representative

Denture Resins, Chairman

Z-E Type Material

J. M. Cassel

Member: C054, Medical Devices Standards Management

Board, Executive Committee

N. W. Rupp

Member: Alloy for Dental Amalgams, Chairman

Dispensers for Alloys and Mercury, Chairman

Mercury for Dental Amalgam, Chairman

Mechanical Amalgamators, Chairman

J. A. Tesk

Member: Base Metal Alloys

Dental Implants, Secretary

Dental Materials, Instruments, & Equipment, Chairman

Porcelain/Alloy Systems

USA TAG for ISO TC106, Chairman

American Physical Society

Division of High Polymer Physics

F. A. Khoury

Member: Executive Committee

Committee on History of DMPP

I. C. Sanchez

Member: Executive Committee, Vice Chairman, 1982-83

Selection Committee, APS High Polymer Physics

Prize, 1982-83

Education Committee, Chairman, 1982

American Society of Mechanical Engineers

R. W. Penn

Member: Reinforced Thermoset Plastic Corrosion Resistant

Equipment

American Society for Testing and Materials

Committee on Research and Technical Planning

E. Passaglia

Member: Subcommittee on Research Chairman

D-2: Petroleum Products and Lubricants

L. J. Zapas

Member: D2.07 Flow Properties

D2.07A Newtonian Viscometry

563-132
D-9: Electrical Insulating Materials

W. P. Harris

Member: D9.05 Ceramic Products

D9.12 Electrical Tests

D9.16 Hookup Wire Insulation

D9.17 Thermal Capabilities

D9.90 Executive Committee

D9.93 Education, Research, and Symposia

D9.94 Nomenclature, Significance, & Statistics

D9.95 Liaison

D-ll: Rubber and Rubber--Like Materials

E. A. Kearsley

Member

G. B. McKenna

Member

D-20: Plastics

R. K. Eby, Chairman

Member: D20.01: Executive Subcommittee

J. D. Barnes

Member: D20.12

D20.13

D20.19

D20.70

Olefin Plastics

Statistics, Chairman

Film and Sheeting

Analytical Methods

WG.07: Gas Permeability

H. L. Wagner

Member: WG.04 Liquid Size Exclusion Chromatography

WG.05 Molecular Weight Parameters, Chairman

J. H. Flynn

Member: D20.30: Thermal Properties

30.7 Fundamental Thermal Methods,

Chai rman

D-27: Electrical Insulating Liquids and Gases

W. P. Harris

Member

D-30: High Modulus Fibers and Their Composites

D. L. Hunston

Member

E-9: Fatique

G. B. McKenna

Member

R. W. Penn

Member

563-133
E- 37 : Thermal Measurements

S. S. Chang

Member: E37.01: Test Methods and Recommended Practices

E37.05: Thermophysical Properties

J. H. Flynn

Member: E37.03: Nomenclature and Definitions, Chairman

E37.90: Executive Subcommittee

E-45: Geothermal Energy and Resources

E. A. Kearsley

Member: E45.02: Materials

F-2: Flexible Barrier Materials

J. D. Barnes

Member: F02.30: Test Methods

F02.93: Statistical Matters, Chairman

WG.30.2: Barrier Methods, Chairman

F-4: Medical and Surgical Materials, and Devices

G. M. Brauer

Member: Executive Committee

F04.20: Resources

WG.01: Polymeric Materials, Chairman

J. M. Cassel

Member: F04.20: Resources

R.K. Eby

Member

G. B. McKenna

Member

Biomedical Research Support Grant

R. L. Bowen

Member: 1982-1983 Review Committee

W. E. Brown

Member: 1982-1983 Review Committee

Case Western Reserve Univ Materials Research Laboratory

Advisory Board

R. K. Eby

Member

Chemical Society of Washington

G. M. Brauer

Chairman, Councilors Committee

Award Committee

DECUS (Digital Equipment Users' Society)

Washington Area MIN- LS I Users'

J. D. Barnes

Chai rman

563-134
Eleventh NATAS Conference

J. H. Flynn

Symposium on Kinetics of Chemical & Physical Processes, Chairman

Ferroelectrics Journal

M. G. Broadhurst

Guest Editor of Special Issue on PVDF

Fifth International Meeting on Ferroelectrics

M. G. Broadhurst

Member: U. S. Committee

Polymer Session Chairman

Geis Foundation for the Advancement of Dentistry

G. C. Paffenbarger

President

Member: Award Committee for Dental Editorial, Chairman

Award Committee for Oral & Maxillofacial Surgery,

Chairman

Award Committee for Periodomtology , Chairman

Government Interagency Panel on Adhesive Bonding Research

D. L. Hunston

Member

International Confederation for Thermal Analysis

J. H. Flynn

Member: Nomenclature Committee

Working Party on Symbols

International Council on Alloy Phase Diagrams

R. M. Waterstrat

Member

International Electrotechnical Commission

TC046, Cables, Wires, & Waveguides for Telecommunication

Equipment

L. J. Zapas

Member: WG.03: Measuring Methods of Polyethylene

TC061, Plastics

L. E. Smith

Member

International Standards Organization

TC106, Dental Materials and Devices

G. M. Brauer

Member: Task Force on Color Stability

N. W. Rupp

Member: Restorative Materials

WG.01: U. S. Delegation, Chairman

TG7: Alloys for Dental Amalgams,

Chai rman

563-135
WG.06: Amalgamation Devices & Accessories,

Chai rman

J. A. Tesk, USA Delegation, Chairman

TC150, Implants for Surgery, USTAG

J. M. Cassel , Chairman

TC150/SC2, Cardiovascular Implants for Surgery, USTAG

J. M. Cassel, NBS Representative

Molecular and Cellular Thermobiology (Journal)

B. Dickens

Member: Editorial Board

National Bureau of Standards Advisory Panel for Tariffs on Electron Microscopes Under Florence Agreement

F. A. Khoury, Member

National Center for Small Angle Scattering

C. C. Han

Member: Users Committee

National Health and Medical Research Council of Australia

G. C. Paffenbarger, Consultant

National Institute of Dental Research

R. L. Bowen

Member: Long Range Research Planning & State-of-the-Science

on Composites, Consultant

Panel on Restorative Materials Program

Review Committee for ADA

National Research Council

Panel on Polymer Science & Engineering

R. K. Eby, Member

Panel on Civil /Navy Ocean Engineering

Task Group on Materials and Structure

Nondestructive Testing of NRC

R. K. Eby, Member

North American Thermal Analysis Society

J. H. Flynn

Editor: NATAS Notes

Member: Awards Committee

Executive Committee

Publications Committee, Chairman

Ohio Dental Association

G. C. Paffenbarger

Member: Callahan Memorial Committee

563-136
Polymer (Journal)

R. K. Eby, U. S. Associate Editor

Polymer Degradation and Stablility (Journal)

J. H. Flynn, Editorial Board Member

Seventh International Conference on Thermal Analysis

J. H. Flynn

Member: Program Committee

Chairman: Session of Polymer Science Section

Society of Plastics Engineers

R. K. Eby

Member: Selection Committee for SPE International

Award for Research, Chairman

G. B. McKenna

Member: Technical Publications

Society of Rheology

D. L. Hunston

Member: Executive Committee

E. A. Kearsley

Member: Executive Committee

G. B. McKenna

Member: Committee on Education

Local Arrangements 1981 Spring Meeting, Chairman

Symposium on FTIR Techniques in Plastics Characterization and

Processing, Williamsburg, VA, March 18, 1982.

J. D. Barnes, Chairman

U.S. Air Force

National Civilian Consultant to the Surgeon General

N. W. Rupp

US/Yugoslav Science and Technology Program

Thermal Degradation of Polymers

J. H. Flynn, Monitor

University of Virginia, Department of Materials Science

G. C. Paffenbarger , Consultant

University of Massachusetts Advisory Board of Polymer Research

Institute

R. K. Eby, Member

Washington

J. D. Area MINC Users GroupBarnes, Chairman

Younger Chemists Committee

G. A. Senich

Member: Activities Committee

563-137
Publ i cations

Antonucci , J. M. ; Misra, D. N. ; Peckoo, R. J. The accelerative and

adhesive bonding capabilities of surface-active accelerators. J. Dent.

Res. 60(7): 1332; 1981.

Bowen, R. L. Historical development of dental composite resins. Dent.

Diamond (Jpn) 6: 8; 1981.

Brauer, G. M. ; Dulik, D. M. ; Hughes, H. N. ; Dermann, K. ; Rupp, N. W. Marginal adaptation of BIS-GMA-based composites containing various

diluents. J. Dent. Res. 60(12): 1966; 1981.

Brauer, G. M. ; Stansbury, J. W. ; Antonucci, J. M. 4-N,N-dialkylaminophenethanols,-alkanoic acids and esters: new accelerators for dental

composites. J. Dent. Res. 60(7): 1343; 1981.

Broadhurst, M. G. ; Micheron, F. ; Wada, Y. Guest editorial. Ferroelectr. J. April 1981.

Broadhurst, M. G. Workshop Proceedings: Morphology of polyethylene

and crossl inked polyethylene. EPRI Contract TPS 81-184; November 1981.

Broadhurst, M. G. ; Davis, G. T. Ferroelectric polarization in polymers.

Ferroelectrics 32: 177; 1981.

Bur, A. J. Resistivity and piezoelectric measurements in oriented &

unoriented thick PVDF films. Polymer 22: 1288; 1981.

Bur, A. J. ; Tsao, A. K. Fabrication of ultra-drawn thick PVDF transducers. Nat. Bur. Stand. (U.S.) NBSIR 81-2418; 1981 December.

Cassel , J. M. ; Tesk, J. A.; Brauer, G. M. ; Antonucci, J. M. ; Wu W. Properties & interactions of oral structures & restorative materials.

Nat. Bur. Stand. (U.S.) NBSIR 81-2431; 1981 December.

Chang, S. S. Specific heat of thermosetting resins —study of phenolic

resin by automated adiabatic calorimetry and differential scanning

calorimetry, chapter in Thermal analysis in polymer characterization.

Turi, E. A., ed. London, England: Heyden & Sons; 1981. p. 98.

Chang, S. S. ; Smith, L. E. ; Senich, G. A. Migration of low molecular

weight additives in polymers. Nat. Bur. Stand. (U.S.) NBSIR 81-2314;

1981 September.

Chiang, C. K. An all --polymeric solid state battery. Polymer

22: 1454; 1981.

Chiang, C. K. ; Franklin, A. D. Electrical impedance spectra of tranpolyacetylene. Solid State Comm. 40: 775; 1981.

Chow, L. C. ; Guo, M. K. ; Hsieh, C. C. ; Hong, Y. C. Apatitic fluoride

increase in enamel from a topical treatment involving intermediate

CaHP04 *2H2 0 formation, an in vivo study. Caries Res. 15: 369; 1981.

563-138
Crissman, J. M. ; Khoury, F. A.; McKenna, G. B. Relationships between

morphology & mechanical properties of ultra high molecular weight

polyethylene. Nat. Bur. Stand. (U.S.) NBSIR 82-2493; 1981.

Dickens, B. Pressure as an important variable in thermogravimetric

studies of polymer degradations. Dollimore, D. , ed. Proceedings

of the 2nd european symposium on thermal analysis; 1981 September;

Aberdeen, Scotland. London, England: Heyden & Sons. 1981. p. 219.

Eby, R. K. ; Broadhurst, M. G. ; Chang, S. S. ; Davis, G. T.

DiMarzio, E. A.; Fanconi , B. M. ; Flynn, J. H. ; Han, C. C.

Khoury, F. A.; Markovitz, H. ; McKinney, J. E. ; Mopsik, F. I.;

Passaglia, E. ; Sanchez, I. C. ; Smith, L. E. ; VanderHart, D. L.

Zapas, L. P. High polymer physics, chapter in American Institute of

Physics 50th Anniversary Handbook. Anderson, H. L. , ed. New York,

NY: American Institute of Physics; 1981.

Eby, R. K. ; Peterlin, A.; Khoury, F. A.; Broadhurst, M. G.

Fanconi, B. M. Crystalline polymers, chapter in State of polymer

science in the U.S. National Research Council; 1981.

Fanconi, B. M. ; DeVries, K. L. ; Smith, R. H. Response to commentary

by M. Dole. Polymer 22: 1460; 1981.

Farmer, B. L. ; Eby, R. K. Energy calculations of the crystal structure of the low temperature phase (II) of polytetrafl uoroethyl ene. Polymer 22: 1487; 1981.

Flynn, J. H. Role of thermal analysis in the lifetime prediction of

polymers. Dollimore, D. , ed. Proceedings of the 2nd European symposium

on thermal analysis; 1981 September; Aberdeen, Scotland. London,

England: Heyden & Sons; 1981. p. 223.

Flynn, J. H. Analysis of thermogravimetric kinetics--overcoming com- plications of thermal history, chapter 3 in Thermal analysis in polymer

characterization. London, England: Heyden & Sons; 1981.

Han, C. C. ; Akcasu, A. Z. On the dynamic structure factor, S(q,w) of

polymers in dilute solutions. Polymer 22: 1019; 1981.

Han, C. C. ; Akcasu, A. Z. Concentration dependence of diffusion

coefficient of various molecular weights and temperatures. Polymer

22: 1165; 1981.

Han, C. C. ; Akcasu, A. Z. Dynamic light scattering of dilute polymer

solutions in the non-asymptotic q-region. Macromolecules 14: 1080; 1981.

Hunston, D. L. ; Bitner, J. L. ; Rushford, J. L. ; Rose, W. S. ; Riew, C. K. Viscoelastic fracture of structural adhesives. J. Adhes. 13: 3; 1981.

Khoury, F. A. Polymer science and engineering: challenges, needs, and

opportunities. National Research Council Report; 1981.

563-139
Khoury, F. A. Workshop proceedings: morphology of polyethylene &

cross-linked polyethylene. 1981 April; Gaithersburg, MD. EPRI Publ.

#EL-2134-LD; 1981 November.

Khoury, F. A. Physics vade mecum. Am. Phys. Soc. ; Chapter 13; 1981.

Lang, S. B. ; Davis, G. T. ; DeReggi , A. S. ; Broadhurst, M. G. Effects

of poling field & time on pyroelectric coefficient & polarization

uniformity in polyvinyl fluoride. Ferroelectrics 33: 119; 1981.

Misra, D. N. ; Bowen, R. L. Interaction of zinc ions with hydroxyl a- patite: adsorption from aqueous solutions. New York, NY: Plenum Press;

1981.

Peterlin, A. Tensile failure of crystalline polymers. J. Macromol.

Sci. Phys. 19: 401; 1981.

Schroeder, L. W. ; Jordan, T. H. ; Brown, W. E. Raman spectrum from a single crystal of SnHP04 Spectrochim. Acta Part A 37: 21; 1981.

Senich, G. A. Inverse gas chromatography, a method for studying

polymer-migrant interactions in polyolefin packaging materials.

CHEMTECH 11: 360; 1981.

Tesk, J. A. Solders and fluxes, chapter in Dentist's desk reference:

materials, instruments, and equipment, 1st Ed. Chicago, IL: American

Dental Association. 1981.

Waterstrat, R. M. Binary phase diagrams of transition elements. Bull.

Alloy Phase Diagrams. 2: 1981. [Excerpt published quarterly by

American Society for Metals as part of the ASM/NBS Data Program for

Alloy Phase Diagrams.]

Waterstrat, R. M. Analysis of selected alloys in the systems Cr-Pd,

Cr-Ru, V-Pd, and Ta-Pt. J. Less-Common Met. 80: 31; 1981.

Weeks, J. J. ; Clark, E. S. ; Eby, R. K. Crystal structure of the low

temperature phase (II) of polytetrafluoroethylene. Polymer 22: 1480;

1981.

Weeks, J. J. ; Eby, R. K. ; Clark, E. S. Disorder in the crystal structures of phases I and II of copolymers of tetrafluoroethylene and

hexafl uoropropylene. Polymer 22: 1496; 1981.

Barnes, J. D. A computer controlled apparatus for gas transmission

measurement. Technical Papers Vol. XXVIII, Society of Plastics

Engineers, Inc. 1982. p. 19.

Bowen, R. L. Composite and sealant—past, present, and future.

Pediatr. Dent. 4 1: 10; 1982.

Bowen, R. L. ; Rapson, J. E. ; Dickson, G. Hardening shrinkage and

hygroscopic expansion of composite resins. J. Dent. Res. 61(5): 654;

1982.

563-140
Broadhurst, M. G. Electric-field induced changes in the phase and

orientation of polyvinyl idene fluoride crystals. Proceedings of the

28th IUPAC macromolecular symposium; 1982 July; Amherst, MA; International Union of Pure and Applied Chemistry. 1982; p. 455.

Broadhurst, M. G. ; Davis, G. T. ; DeReggi , A. S. ; Roth, S. C.

Collins, R. E. Pyroelectricity and charge transport in a copolymer

of vinyl idene fluoride and tetrafluoroethylene. Polymer 23: 22; 1982.

Brown, D. W. ; Lowry, R. E. ; Smith, L. E. Hydrolytic degradation of

polyester polyurethanes containing carbodi imides. Macromolecules

15: 453; 1982.

Brown, D. W. ; Lowry, R. E. ; Smith, L. E. Equilibrium acid concentration in hydrolyzed polyester diols & polyester polyurethanes. Polym.

Prepr. 23; 1982.

Brown, D. W. ; Lowry, R. E. ; Smith, L. E. Prediction of the long term

stability of polyester-based recording media. Nat. Bur. Stand. (U.S.)

NBSIR 82-2530; 1982.

Bur, A. J. Fabrication and characterization of ultra-drawn thick PVDF

transducers. Proceedings of the 28th IUPAC macromolecular symposium;

1982 July; Amherst, MA; International Union of Pure and Applied

Chemistry. 1982; p. 457.

Chang, S. S. Migration of low molecular weight components from polyolefins. Proceedings of the 28th IUPAC macromolecular symposium;

1982 July; Amherst, MA; International Union of Pure and Applied Chemistry. 1982; p. 734.

Chang, S. S. ; Bernstein, G. ; West, E. D. ; Ditmars, D. A.; Ishihara, S. Enthalpy and heat capacity standard reference material —synthetic

sapphire (a-Al 2 03 ) from 10 to 2250 K. J. Res. Nat. Bur. Stand. (U.S.)

87: 159; 1982.

Chang, S. S. ; Senich, G. A. ; Smith, L. E. Migration of low molecular

weight additives in polyolefins and copolymers. Nat. Bur. Stand.

(U.S.) NBSIR 82-2472; 1982 March.

Crissman, J. M. ; McKenna, G. B. ; Khoury, F. A. Creep and stressrelaxation behavior of ultra high molecular weight polyethylene in

uniaxial extension and compression. Society of Plastics Engineers

Technical Papers, Vol. XXVIII; San Francisco, CA: SPE/ANTEC, 1982

May 9-13.

Davis, G. T. ; Furukawa, T. ; Lovinger, A. J. ; Broadhurst, M. G. Structural and dielectric investigation on the nature of the transition in

a copolymer of vinyl idene fluoride & trifluoroethylene (52/48 mol %).

Macromolecules 15: 329; 1982.

Dehl , R. E. ; Grant, W. G. ; Cassel , J. M. Characterization of porosity

in porous polymeric implant materials. Nat. Bur. Stand. (U.S.) NBSIR

81-2459; 1982 February.

563-141
Dickens, B. Thermally degrading polyethylene studied by means of

factor- jump thermogravimetry. J. Polym. Sci. 20: 1065; 1982.

Dickens, B. Thermal degradation study of isotatic polypropylene using

factor- jump thermogravimetry. J. Polym. Sci. 20: 1169; 1982.

Dickens, B. Vapor composition profiles estimated for thermally

degrading polyethylene. Thermochim. Acta 55: 217; 1982.

Eby, R. K. Disorders in the crystal structure of homo- and co-polymers

of polytetraf 1 uoroethylene. Proceedings of the 28th IUPAC macromolecular

symposium; 1982 July; Amherst, MA; International Union of Pure and

Applied Chemistry. 1982; p. 592.

Eby, R. K. ; Smith, L. E. ; Peterlin, A.; Broadhurst, M. G. ; Fanconi, B. M.

;

Cassel , J. M. ; Sanchez, I. C. Polymer science and standards division 1981.

Nat. Bur. Stand. (U.S.) NBSIR 82-2452; 1982 March.

Fanconi, B. M. Chain scission and mechanical degradation of polyethylene. Proceedings of the 28th IUPAC macromolecular symposium;

1982 July; Amherst, MA; International Union of Pure and Applied

Chemistry. 1982; p. 34.

Fanconi, B. M. ; Colson, J. P. ; DeVries, K. L. ; Smith, R. H. Free

radicals and new end groups resulting from chain scission: II. mechanical degradation of polyethylene. Polymer 23: 1027; 1982.

Flynn, J. H. Lifetime prediction from polymer degradation kinetics.

Proceedings of the 28th IUPAC macromolecular symposium; 1982 July;

Amherst, MA; International Union and Pure and Applied Chemistry.

1982; p. 322.

Flynn, J. H. A collection of kinetic data for the diffusion of organic

compounds in polyolefins. Polymer 23: 1325; 1982.

Hosier, W. R. Electrical conductivity measurements on mixed ionic/

electronic conducting materials at high temperatures. Proceedings of

the 8th symposium on thermophysical properties, 1981 June; Gaithersburg,

MD. Nat. Bur. Stand. (U.S.) Spec. Publ.; 1982.

Hunston, D. L. ; Kinloch, A. J. ; Shaw, S. J. Crack propagation in

rubber toughened epoxies. Proceedings of the international conference

on deformation, yield, and fracture; 1981; London, England: Plastics

and Rubber Institute. 1982; p. 78.

Hunston, D. L. ; Rushford, J. L. ; Wang, S. S. ; Kinloch, A. J. Developing

failure criteria for the polymers used in structural adhesives.

Proceedings of the SPI conference on reinforced plastics/composites;

1982 January 11-15; New York, NY: The Society of the Plastics Industry,

Inc. ; paper 29C. 1982.

Khoury, F. A. The morphology of polymers. Polym. Prepr. Japan

31: 5; 1982.

563-142
Lovinger, A. J. ; Davis, G. T. ; Furukawa, T. ; Broadhurst, M. G.

Crystalline forms in a copolymer of vinylidene fluoride & trifluoroethylene (52/48 mol %). Macromolecules 15: 323; 1982.

Mathew, M. ; Kingsbury, P. ; Takagi, S. ; Brown, W. E. A new struvitetype compound, magnesium sodium phosphate heptahydrate. Acta

Crystal logr. Sect. B 38: 40; 1982.

McCrackin, F. L. ; Guttman, C. M. ; Han, C. C. Monte Carlo calculations

of the inverse radii of polymers in theta solvents and good solvents.

Proceedings of the 28th IUPAC macromolecular symposium; 1982 July;

Amherst, MA; International Union of Pure and Applied Chemistry. 1982;

p. 524.

McKenna, G. B. ; Penn, R. W. The mechanical durability of candidate

elastomers for blood pump applications. Winter, G. ; Plenk, H.

Gibbons, D. , eds. Proceedings of the 1st world biomaterials congress,

1980 April; Vienna, Austria. New York, NY: J. Wiley & Sons, Ltd.; 1982.

McKinney, J. E. Apparatus for measuring wear of dental restorative

materials. Wear 76: 337; 1982.

Mopsik, F. I.; DeReggi , A. S. Numerical evaluation of the dielectric

polarization distribution from thermal pulse data. J. Appl. Phys.

53: 4333; 1982.

Paffenbarger, G. C. ; Rupp, N. W. ; Patel, P. R. Copper-free amalgams:

dimensional change after approximately five years at 60, 37, and 23 °C.

J. Dent. Res. 61(6): 811; 1982.

Paffenbarger, G. C. ; Rupp, N. W. ; Waterstrat, R. M. Metals in solution

in mercury expressed from copper-rich dental amalgams. J. Dent. Res.

61(1): 30; 1982.

Passaglia, E. Relaxation of stresses in crazes at crack tips & rate o'f craze extension. Polymer 23: 754; 1982.

Peterlin, A. Dynamic viscosity of polymer solutions. Colloid. Polym.

Sci. 260: 278; 1982.

Peterlin, A.; DeCandia, F. ; Russo, R. ; Vittoria, V. Mechanical and

transport properties of drawn crossl inked low-deni sty polyethylene.

J. Polym. Sci. 20: 269; 1982.

Peterlin, A.; DeCandia, F. ; Russo, R. ; Vittoria, V. Shrinkage and

retractive forces during the annealing of drawn low-density

polyethylene. J. Polym. Sci. 20: 1175; 1982.

Rubin, R. J. ; Weiss, G. H. Random walks on lattices: the problem of

visits to a set of points revisited. J. Math. Phys. 23: 250; 1982.

Sanchez, I. C. Theory of polymer-polymer blend phase behavior.

Kern. Ind. 31: 199; 1982.

563-143
Sanchez, I. C. Thermodynamic properties of polymer blends. Proceedings

of the 28th IUPAC macromolecular symposium; 1982 July; Amherst, MA;

International Union of Pure and Applied Chemistry. 1982; p. 660.

Sanchez, I. C. Equation of state theories of polymer blends.

Sole, Karl, ed. Proceedings of the international symposium on polymer

compatibility: principals and practices, vol . 3. 1980 December;

Midland, MI. Midland, MI: MMI Press; 1982 August; p. 201.

Senich, G. A. Chromatographic studies of diffusion in polymers.

Proceedings of the 28th IUPAC macromolecular symposium; 1982 July;

Amherst, MA; International Union of Pure and Applied Chemistry.

1982; p. 740.

Takagi, S. ; Mathew, M. ; Brown, W. E. Water-rich hydrates: the structures of dimagnesium potassium hydrogenbis(arsenate) 15-hydrate and

dimagnesium potassium hydrogenbis(phosphate) 15-Hydrate. Acta

Crystal logr. Sect. B 38: 44; 1982.

VanderHart, D. L. 13 C NMR in oriented polymers. Proceedings of the

28th IUPAC macromolecular symposium; 1982 July; Amherst, MA; International Union of Pure and Applied Chemistry. 1982; p. 4.

VanderHart, D. L. Deductions about the morphology of wet and wet

beaten celluloses from solid state 13 C NMR. Nat. Bur. Stand. (U.S.)

NBSIR 82-2534; 1982.

VanderHart, D. L. ; Earl, W. L. Measurement of 13 C chemical shifts

in solids. J. Magn. Reson. 48: 35; 1982.

Young, R. A.; Brown, W. E. Structures of biological minerals, chapter

in Biological mineralization and demineralization. Nancollas, G. H. , ed.

New York, NY: Springer-Verlag; 1982. p. 101.

Zapas, L. J. Nonlinear mechanical behavior of polymer solutions at

various concentrations. Proceedings of the 28th IUPAC macromolecular

symposium; 1982 July; Amherst, MA; International Union of Pure and

Applied Chemistry. 1982; p. 860.

Barnes, J. D. Standard reference materials for gas transmission

measurements. ACS Symposium Series; in press.

Bowen, R. L. ; Cobb, E. N. ; Rapson, J. E. Adhesive bonding of various

materials to hard tooth tissues. XXV: improvement in bond strength

to dentin. J. Dent. Res.; in press.

Broadhurst, M. G. ; Bur, A. J. ; Schwartz, R. B. The effect of neutron

irradiation on electric conductivity in cellulose acetate. Radi at.

Prot. Dosim. ; in press.

Crissman, J. M. ; Zapas, L. J. The mechanical behavior of isotatic

polypropylene subjected to various strain histories in uniaxial

extension. Polymer; in press.

563-144
DeReggi, A. S. ; Lang, S. ; Mopsik, F. I. Preexisting polarization and

influence of electrode materials on PVF 2 electrics as determined by

thermal pulse and pyroelectric methods. J. Appl. Phys. ; in press.

Dermann, K. ; Rupp, N. W. ; Brauer, G. M. Effect of hygrophilic diluents

on the properties of cured composites. J. Dent. Res.; in press.

DeRossi, D. ; DeReggi, A. S. ; Broadhurst, M. G. ; Roth, S. C.

Davis, G. T. Method of evaluating the thermal stability of the pyroelectric properties of polyvinyl i dene f 1 uoride--effects of poling

temperature & field. J. Appl. Phys.; in press.

Dickens, B. Factor- jump thermogravimetry as applied to the study of

polymer degradations, chapter in Advances in fundamentals of polymer

stability & degradation. Jellinick, H. H. G. , ed. New York, NY:

Elsevier Press; in press.

Dickens, B. ; Florin, R. E. User's guide for the chemiluminescence

apparatus. Nat. Bur. Stand. (U.S.) NBSIR; in press.

Dickens, B. ; Flynn, J. H. Thermogravimetry applied to polymer

degradation kinetics, chapter in Instrumental and physical

characterization of macromolecules. Craver, C. D. , ed. American

Chemical Society Advances in Chemistry Series; in press.

Eby, R. K. ; Davis, G. T. ; Wang, F. W. ; Broadhurst, M. G. ; Fanconi , B. M. Sanchez, I. C. ; Cassel , J. M. Polymer science and standards division.

Kobunshi Ronbunshu; in press.

Eby, R. K. ; Davis, G. T. ; Wang, F. W. ; Broadhurst, M. G. ; Fanconi, B. M. Sanchez, I. C. ; Cassel, J. M. Polymer science and standards division.

Polym. News; in press.

Flynn, J. H. ; Florin, R. E. Polymer degradation and pyrolysis mechanisms, chapter 4 in Polymer characterization using gas chromotography.

New York, NY: Marcel Dekker; in press.

Han, C. C. ; Amis, E. J. Cooperative and self-diffusion of polymers

by dynamic light scattering in semidilute solutions. Polymer; in press.

Han, C. C. ; Fujimoto, T. ; Nagasawa, M. ; Noda, I.; Choshi , H.

Furuhashi , H. ; Matsushita, Y. Preparation and characterization of

block copolymers of H-styrene and D-styrene. Polym. J. ; in press.

Han, C. C. ; Schaefer, D. Application of photon correlation spectroscopy. Pecora, R. , ed. New York, NY: Plenum Press; in press.

Hunston, D. L. ; Rushford, J. L. ; Newitt, W. R. ; Vandreuil, B. A. Rheology of cure for intaglio printing inks. Org. Coat. Plast.

Prepr. ; in press.

Hunston, D. L. ; Wang, S. S. ; Kinloch, A. J. Characterization of fracture behavior of adhesive joints. Org. Coat. Plast. Prepr.; in press.

563-145
Kranbuehl , D. E. ; Verdier, P. H. Interpretation of quasi-elastic light

scattering data for flexible chains: model dependence. Polymer; in press

Mabie, C. P. ; Menis, D. L. ; Whitenton, E. P. ; Trout, R. L.

;

Metherate, R. S. ; Ferry, C. H. Gel-route preparation of low fusing

dental porcelain frit. J. Biomed. Mater. Res.; in press.

Mabie, C. P. ; Menis, D. L. ; Whitenton, E. P. ; Trout, R. L.

;

Metherate, R. S. ; Ferry, C. H. Comparison of gel-route and commer- cially prepared low fusing dental porcelain frit. J. Biomed. Mater.

Res. ; i n press.

McCrackin, F. L. ; Guttman, C. M. ; Han, C. C. Monte Carlo calculation

of the hydro-dynamic radius at the 6 point: deviations from analytical

Gaussian behavior. Macromolecules; in press.

McKenna, G. B. ; Zapas, L. J. Experiments on the small strain behavior

of crossl inked natural rubber, parts I and II. Polymer; in press.

McKinney, J. E. ; Wu, W. Relationship between subsurface damage and

wear of dental restorative composites. J. Dent. Res.; in press.

McKinney, J. E. ; Wu, W. Influence of chemical softening on wear of

three types of dental components. J. Dent. Res.; in press.

Mopsik, F. I.; DeReggi , A. S. The poling behavior of polyvi nyl i dene

fluoride at room temperature. J. Appl. Phys. ; in press.

Paffenbarger , G. C. ; Rupp, N. W. ; Patel, P. R. Dimensional changes

on a high-tin content amalgam. J. Dent. Res.; in press.

Peterlin, A. Diffusion and permeability of polymers, chapter in

Controlled drug delivery. CRC Press; in press.

Peterlin, A. Accordion type laser-Raman (ALR) scattering by polymers.

J. Polym. Sci . ; in press.

Peterlin, A. Polymer morphology & mechanics: the strength & stiffness

of polymers. New York, NY: Marcel Dekker, Inc.; in press.

Phillips, J. C. Mechanical relaxation of liner materials in acetic

acid. Nat. Bur. Stand. (U.S.) NBSIR; in press.

Phillips, J. C. Transport of acetic acid in polyethylene, Nat. Bur.

Stand. (U.S.) NBSIR; in press.

Phillips, J. C. ; Peterlin, A. Diffusion of ethyl acetate vapor in

strained low density polyethylene. Polym. Eng. Sci.; in press.

Rubin, R. J. ; Weiss, G. H. Random walks: theory and selected applications. Adv. Chem. Phys.; in press.

563-146
Sanchez, I. C. ; Poser, C. I. Surface thermodynamics of polymers:

theory. Mittal, K. L. , ed. Proceedings of the international symposium

on physico-chemical aspects of polymer surfaces; 1981 August;

New York, NY: American Chemical Society; in press.

Senich, G. A. A review of the migration of food-contact organotin

stabilizers from poly(vinylchloride). Polymer; in press.

Takagi , S. ; Mathew, M. ; Brown, W. E. The crystal structure of sodium

strontium phosphate nonahydrate. Acta Crystal logr. ; in press.

Tung, M. S. ; Brown, W. E. Characterization & modification of electrochemical properties of teeth. J. Dent. Res.; in press.

Vogel, G. L. ; Chow, L. C. ; Brown, W. E. A microanalytical procedure

for the determination of calcium, phosphorus, and fluoride in enamel.

Caries Res.; in press.

Wagner, H. L. ; Dillon, J. G. A low-shear high temperature viscometer:

the viscosity of ultrahigh molecular weight polyethylene. ACS Symposium

Issue; in press.

Wang, F. W. ; Howell, B. F. Fluorescence measurement of antioxidant

migration from low-density polyethylene into 1-propanol. Proceedings

of the ACS organic coatings and applied polymer science symposium;

1982 September; Kansas City, MO: American Chemical Society; in press.

Wang, F. W. ; Lowry, R. E. Measurement of polymer-polymer compatibility

by non-radiative energy transfer technique. Polym. Prepr. ; in press.

Wang, F. W. ; McCrackin, F. L. Analysis of ultracentrifugation interference patterns with image digitizer: application to molecular

weight determination of SRM 1478 polystyrene. Polymer; in press.

Wu, W. Application of small angle x-ray technique in damaged particulate reinforced composites: a theoretical treatment. Polymer; in press.

Wu, W. Small angle neutron scattering of partially segregated polymer

blends. Polymer; in press.

Wu, W. ; McKinney, J. E. Influence of chemicals on wear of dental

composites. J. Dent. Res.; in press.

Sponsored Conferences

Symposium on Random Walks and Their Applications to the

Physical and Biological Sciences, June 28-July 1, 1982

at NBS, Gaithersburg, MD

External Recognition

Poster Recognition

Sybron/Kerr "Milestones in Dentistry--1891-1981

January 1982

R. L. Bowen

563-147
Honorary Membership

Omicron Kapper Upsilon Honor Dental Society

May 1982

R. L. Bowen

1982 Clemson Award for Contributions to the Technical Literature

April 1982

R. L. Bowen

Honorary Membership

Zeta Zeta Chapter for Omicron Kappa Upsilon

Georgetown University

May 1981

J. M. Cassel

Irwin Vigness Memorial Award for 1982 from the Institute for

Environmental Sciences for a paper on a fiber optics strain gauge

S. Edelman

North American Thermal Analysis Society

J. H. Flynn, Fellow

October 1981

Royal Netherlands Academy of Sciences

Corresponding Membership

H. P. R. Frederikse

August 1982

Plastics Hall of Fame

Frank W. Reinhart

June 1982

Patents

Tertiary Aromatic Amine Accelerators Derived from Para-amino

Phenethanol in Vinyl Monomers

H. Argentar

August 18, 1981

U. S. Patent 4,284,551

Method for Preparing Microporous Glassy Filler Grains for Dental

Resin Composites

C. P. Mabie and D. L. Menis

December 22, 1981

U. S. Patent 4,306,913

Improved Dental Material

C. P. Mabie and D. L. Menis

Filed January 22, 1982

Combinations of Sparingly Soluble Calcium Phosphates in Slurries and

Pastes as Mineralizers and Cements

W. E. Brown and L. C. Chow

Filed April 26, 1982

563-148
Industrial Interactions

Industrial Research Associates

Exxon Chemical/David Lohse/Charles Han, SANS study of polyolefin

blendsmaterial s measurement and characterization.

General Electric/Carl Hansen/F. I. Mopsik, Measurement technology

using state-of-the-art time domain dielectric spectrometer

built at NBS. Work agreed to and agreement being processed

for start in September 1982.

Martin Marietta Aerospace/B. N. Ranganathan/L. E. Smith,

Characterization of organic composite resin state of cure- measurement technology for processing.

Rheology Research/Ell iot Kearsley/R. K. Eby, Design and evaluation of measurement methods for polymer solutions-mathematical

modeling of polymer solutions.

American Dental Association/24 Research Associates/J. M. Cassel

Group Leader, Dental and Medical Materials Group, Measurement

relevant to dental materials, dental enamel chemistry, caries

formation, and caries research.

Other Industrial Guest Workers

Union Carbide/Park Leung/Charles Han, Sans investigation of

polymersurfactant i nteractions

Howmedica, Inc. /John Saneiki/John Tesk, Evaluation of new NBS

bonding test.

Dentsply International/Orville Franklin/John Tesk, Evaluation

of New NBS bonding test.

Utah Research Institute/K. W. Zilm/David VanderHart, Effects

of Processing Conditions on Polyethylene Terephthalate Fibers.

Williams Gold/James Arnold/John Tesk, Evaluation of New NBS

Bonding Test.

Archival Technical Papers Coauthored With Industrial Employees

Crystalline Forms in a Copolymer of Vinylidene Fluoride and

Trifluoroethylene (52/48 mol %)/G. T. Davis and M. G. Broadhurst

with Andrew J. Lovinger and T. Furukawa, Bell Laboratories.

Structure and Dielectric Investigation on the Nature of the

Transition in a Copolymer of Vinylidene Fluoride and Trifluoroethylene (52/48 mol %)/G. T. Davis and M. G. Broadhurst with

Andrew J. Lovinger and T. Furukawa, Bell Laboratories.

563-149
13 C NMR in Oriented Polymers/D. L. VanderHart with G. G. A. Bohme

and V. D. Mochel , Firestone Tire and Rubber Co.

Surface Thermodynamics of Liquid Polymers: Theory/I. C. Sanchez

with C. I. Poser, 3M Company.

Development of test Method for Interlaminar Fracture Energy of

Composites/D. L. Hunston, Joint Project with Hercules

(C. W. Bascom) and NASA will yield publication.

Publications with American Dental Association authors.

Formal Visits

Flexible Packaging Association/5/20/82, Polymers used in

packaging-permeation, mechanical durability.

Society of Automotive Engineers/10/81, Mechanical Durability

of Polymeric Materials and development of improved test for

environmental stress cracking.

Johnson and Johnson Dental Products/3/11/82, 3/18/82 and

6/29/82, Feasibility of licensing adhesive process developed

at NBS.

Dentsply, Inc./4/13/82, Dental composite research directions.

Coors Biomedical Co/3/24/82, Dental applications for improved

porcelains.

Unitech, Corp. /3/4/82, Dental ceramic research.

U.S. Army R&D Command/1/20/82, 5/21/82 and 6/11/82, Polymers

used in DOD applications, permeation, characterization, degradation.

Oak Ridge National Laboratory/5/20/82, Degradation of polymers,

mechanical properties, characterization.

Defense Advanced Research Projects Agency (DARPA), 3/3/82,

NDE, mechanical durability, chemical durability, composites,

characterization and electrical properties.

Zarn, Inc. 6/3/82, Mechanical durability, chemical durability,

composite, characterization and electrical properties.

NC Science and Technology Research Center, 6/3/82, Mechanical

durability, chemical durability, composites, characterization

and electrical properties.

Xerox/9/23/82, Overviews of programs.

3M Corp/9/82, Overviews of programs.

563-150
National Research Ccouncil of Canada, 9/82, Overviews of

programs.

Participation in Measurement Programs

ASJM Round Robin, High Temperature GPC, Herman Wagner.

ANSI Round Robin, Measurement of Acid Content of PET,

Daniel Brown.

ASTM Round Robin, Draft Method for Environmental Stress Cracking

of Polyolefins, John Crissman.

ASTM Method D1505, Data for Accuracy of Density of Plastics

Measured by the Density Gradient Method, Leonard Bolz and

John Barnes.

Advisory Activities

Workshop on Ultimate Recycling of Plastics sponsored by Plastics

Inst, of America, F. Wang, J. Flynn

Workshop on Polymer Opportunities, sponsored by Defense

Advanced Research Projects Agency, R. K. Eby, M. G. Broadhurst,

B. M. Fanconi.

Workshop on Polymer Evaluation and Testing sponsored by Defense

Advanced Research Projects Agency, R. K. Eby, L. E. Smith,

B. M. Fanconi.

Workshop on Soil Shock Sensors sponsored by Department of

Defense, M. G. Broadhurst.

Workshop on Electro-Active Polymers sponsored by Los Alamos

Laboratory, M. G. Broadhurst.

563-151

METALLURGY DIVISION (564)

R. Mehrabian, Chief

D. M. G. Summers, Secretary

The mission of the Metallurgy Division is to provide data, measurement

methods, standards and reference materials, scientific database, and

information on the fundamental aspects of processing, structure, physical

properties, and performance of metals and alloys to industry, Government

agencies, and scientific organizations. The activities of the Division

are aimed at a spectrum of technologies with wide generic applications.

The program of the Division involves studies of metals and alloys in

order to foster their safe, efficient, and economical utilization to

meet our long-term national needs within the larger framework of the

materials cycle. Competences are developed and maintained in four

general areas: chemical metallurgy with special emphasis on phase

diagrams and phase stability; process metallurgy including emphasis on the measurement and science base for innovative processing technologies;

quantitative microstructural characterization including nondestructive

evaluation (NDE); and properties including friction, wear, and the

application of metals as synthetic orthopedic implants. The Division

also makes a significant contribution as a national resource of metallurgical information through its Diffusion Data Center and Alloy Data

Center. It provides consultation and assistance to other Government

agencies and standards organizations in the development of necessary

test methods and standards. The programs of the Metallurgy Division are designed to help us meet our future national needs for materials, which

will depend in large measure on our response to forces which are now

well recognized. Some of these are classical laws of supply and demand;

others include such national problems as energy, environment, productivity,

the need to foster long-term high-potential payoff technologies, and

such international problems as materials availability from third world

nations.

For example, our Division, in addition to being involved in theoretical

and experimental studies of phase stability, has a joint effort with the

American Society for Metals (ASM) to provide critically evaluated phase

diagrams to the metallurgical community. The ASM is presently getting a $4 M commitment from the metals producer and user industries for their

contribution to this program. Advancement in the understanding of phase

diagrams and the development of predictive models for phase stability

are essential in the development of new alloys for our future needs.

These could include stronger and lighter alloys for the transportation

industry to improve energy cost, new alloys specifically designed to

exploit the beneficial effects of innovative new processes such as those

referred to as rapid solidification processes, and alloys which would

permit substitution for scarce or unavailable elemental constituents.

The ASM/NBS program has expanded to include 27 outstanding scientists

throughout the world who are assigned the evaluation of specific binary

alloy systems. The Metallurgy Division is not only responsible for the

overall technical guidance of this program, but has also undertaken to:

564-3
• evaluate the important iron, aluminum, and titanium binary systems.

• develop a model computer database system for storage and retrieval

of the evaluated phase diagram data.

• develop a computer graphic system for binary and higher order phase

diagrams.

A major development during the past year was the appropriation of $3 M,

for one year only, by Congress for expansion of our activities and

facilities in Metals Processing. The activities included rapid solidification processing, coatings, and the phase diagram program noted above.

The two new metals processes, rapid solidification and coatings, were identified and selected based on existing competences and the high

leverage that the Metallurgy Division activities will have on earlier

private sector adaptation and exploitation of these emerging technologies.

This funding has allowed establishment of advanced metals processing

facilities that will be used as part of a continuing program to provide

measurements, predictive models, and standards needed for these technologies.

Cooperation is being established with industry to supply samples, measure

critical data, and provide guidelines to industrial designers who are developing new alloys. During the past year, numerous guest workers,

industrial scientists, and distinguished visiting faculty members, such

as Professor D. Turnbull of Harvard University, have come to NBS to

participate in this program, for periods up to six months, and exchange

information concerning these technologies.

The detailed, programmatic content of the Division that follows is

described in the four general task areas. The four tasks in the

Metallurgy Division are specifically related to two programmatic initiatives (the FY80 Durability and FY82 Metals Processing Initiatives), a competence initiative (the FY80 Synchrotron Initiative), and the major

agreement on phase diagrams between the ASM and NBS:

Task 12142- -STRUCTURE CHARACTERIZATION. Addresses the Synchrotron

Competence Initiative, the application of NDE (Acoustic Emission

and Ultrasonics) to materials characterization, and the activities

on Analytical Electron Microscopy.

Task 12143- -METALLURGICAL PROCESSING. Contains all of the Division's

competences in metals processing (e.g., rapid solidification,

surface modification, coatings, etc.) and was expanded through the

FY82 Metals Processing Initiative. The Diffusion in Metals Data

Center is located in this task.

Task 12144- -MECHANICAL PROPERTIES AND WEAR. This recently expanded

task contains all the Wear activities initiated in the FY80 Durability

Initiative. It also contains the research activities on the use of

metals as synthetic implants.

Task 12145--CHEMICAL METALLURGY. The Alloy Data Center is in this

task. The joint ASM/NBS cooperative agreement utilizes the resources

of this task to develop and disseminate critically evaluated phase

564-4
diagrams, and on-line computer graphics systems coupled to predictive

thermodynamic models. The quarterly ASM/NBS Bulletin of Alloy

Phase Diagrams is also published under this task.

The technical activities under the various tasks are closely interrelated

and address the overall mission of the Division to meet our present and

future societal needs for metals. The central purpose of these scientific

activities is to probe the relationships among processing conditions,

the internal structure of metals, and their properties and performance.

The resulting knowledge can be used to efficiently produce, shape, and

otherwise process metals to control their properties and achieve the

desired reliable and durable performance in the finished product.

Critical data compilations are being developed and delivered to users concerned with alloy properties, diffusion, and phase diagram information.

Standard reference materals are being produced for electron microscope

calibration, electron microprobe analysis, and electrical conductivity.

Contributions are made to NBS programs in nondestructive evaluation, and

artificial implants.

FY82 Significant Accomplishments

Task 12142--STRUCTURE CHARACTERIZATION. This Task's accomplishments

are in two major areas: (1) The competence program in which the

application of synchrotron radiation to materials science is being

investigated. The Metallurgy Division is taking a lead in the

o o construction of hard radiation (0.5 A to 5 A) branch lines at the

National Synchrotron Light Source (NSLS) in Brookhaven National

Laboratory (BNL) for the Center for Materials Science (CMS) and the

Naval Research Laboratory (NRL) scientists to perform unique experiments for research problems in materials science. (2) The new initiative for Metals Processing, where this task's efforts lie in

the improvement of microstructure characterization facilities.

• The CMS Synchrotron Radiation Beam Lines at the National Synchrotron

Light Source (NSLS) in Brookhaven are being assembled. These

include two monochromator tanks, two hutches (experimental stations

for small angle scattering and real-time topography) and beam

transport mechanisms.

• A quantitative microscopy facility is being established which

includes a new Transmission Electron Microscope (TEM), a Quantimet,

and a new x-ray analysis capability for one of our Scanning Electron

Microscopes (SEMs), as part of the new effort for Metals Processing.

• A new four megabyte capacity minicomputer has been installed for

analysis of varieties of data ranging from acoustic emission (AE)

signals to predictive modeling computation of phase diagrams.

• A new laser interferometer has been built for microstructure characterization by acoustic emission.

564-5
• White radiation topography techniques have been developed and

applied to the characterization of Czochralski grown Fe-Al crystals,

Ni crystals, A1 and Sn powders, A1 polycrystals, NaCl crystals,

electron beam melted Si crystals, A1 2 0 3 , 2024 A1 , and human teeth.

• A second generation charge-coupled-device image intensifier for

real-time topography has been developed.

• The in-house focused Extended X-ray Absorption Fine Structures

(EXAFS) and Surface Extended X-Ray Absorption Fine Structures

(SEXAFS) have been used to study various amorphous materials such

as metallic glasses and ultra-thin passive films on metals and

alloys.

Task 12143—METALLURGICAL PROCESSING.

• Major new facilities were designed and put in place in the Metals

Processing Laboratory. Facilities are now available to study all

three major types of rapid solidification: powder production,

ribbon production, and surface treatment. New facilities being

added include atomization systems for production of iron, aluminum,

and superalloy powders; a hot isostatic press for consolidation of

these powders; and a laser system for alloy surface treatment. In

addition, electron beam and melt spinning systems were modified to

provide significantly improved capabilities for measurement and

control of solidification conditions.

• These new facilities are now being used by NBS, industry, other

Government agencies, and university workers for innovative studies

on metallic glass properties, alloy coatings, surface modifications,

and alloy powders, especially as influenced by solidification

dynamics. Large interactive programs have been initiated with

universities, involving 12 visiting faculty members during the past

year, more than 20 students, and contracts with 3 universities for

work on metals processing measurement and techniques.

• A new system for producing submicron-size rapidly solidified alloy

powders by electrohydrodynamic atomization techniques was used to

study solidification dynamics in aluminum alloys subjected to large

amounts of undercooling.

• Rapid solidification conditions that produce extended solid solubility

in Ag-Cu alloys were determined. Experimental tests at solidification

velocities of 100 cm/s yielded single phase alloys having compositions

well beyond the equilibrium solubility limit.

• Alloy coatings produced by diffusion- induced grain boundary migration

were measured quantitatively with electron microprobe area composition

scans. Kinetic mechanisms yielding this new effect were analyzed.

Appreciable alloying was achieved in the regions through which the

grain boundaries migrated even when oxygen was introduced as an impurity into the regions being alloyed.

564-6
• Spatial averaging techniques were applied to ultrasonic pulse-echo

measurements developed for j_n situ determination of positions and

velocities of solidification interfaces. The signal-to-noise ratio

in large grained specimens where grain scattering problems interfere

with interpretation was substantially improved.

• A customized system was designed and put into operation for computerization of bibliographic and other information contained in the

Diffusion in Metals Data Center. This system allows detailed

searching for diffusion data references according to type of diffusion, alloying elements, and alloy composition.

Task 12144—MECHANICAL PROPERTIES AND WEAR.

• Implementation has begun of portions of the new Metals Processing

Initiative that pertain to mechanical properties and wear. A

plasma transfer arc system is on order that will permit the controlled

production of alloy coatings that will be studied next year. New

mechanical test and wear test equipment has been identified and

will be ordered with expected FY83 funds. Plans for research

studies of metal coating properties and performance have been

developed including fatigue wear, impact wear, coating adhesion

bend strength, modulus, and others.

• The first NBS abrasive wear reference material has been produced

and is now available for purchase. This material, D-2 tool steel,

will be used to certify abrasive wear testing in industry.

• A new standard practice for conducting solid particle impact erosion

tests has been developed with leadership from this task and also

approved by the American Society for Testing and Materials (ASTM).

This is the first U.S. standard for erosion testing.

• One staff member assumed the chairpersonship of ASTM G2 on Erosion

and Wear.

• A new theory of sliding wear was developed at NBS during the visit

of two guest workers from the University of Virginia. This new theory predicts wear effects associated with specific material

properties, such as flow stress and slip system geometries.

• A microhardness symposium was organized and held at NBS involving

presentations of nine research papers in this area. A larger

standards-related meeting is being planned for next year.

• Recent galling wear studies on a series of copper-based alloys have

shown effects attributed to stacking fault energy variations with

composition in the alloys.

• A postdoctoral fellow (National Research Council) has initiated a study of wear effects in titanium alloys, emphasizing fundamental

aspects and utilizing analytical electron microscope techniques.

564-7
• A new standard was developed with NBS leadership concerning testing

of pitting and crevice corrosion of metallic implant materials.

This laboratory test will permit assessment of corrosion-resistance

differences between alloys for implant related applications.

• Experiments and theoretical studies are in progress concerning

interface strengths at metallic implant surfaces bonded to polymer

materials. Analysis has shown torsional loading effects as being a critical concern in certain implant device applications.

• Laboratory corrosion studies of cobalt-based alloys used in implant

applications have shown a strong effect of the concentration of

iron (a minor alloying element) on performance.

• Studies of the effect of several surface treatments on the corrosion

fatigue life of titanium implant alloys in saline solution have

shown a beneficial response of particular mechanical surface roughing

treatment, presumably resulting from deformation patterns induced

into the surface regions.

Task 12145--CHEMICAL METALLURGY.

• Four issues of the Bulletin of Alloy Phase Diagrams are now published

each year. Graphics have been prepared at NBS and computer files

for the published systems are maintained on the UNIVAC 1100/82.

Approximately 80 new binary diagrams have been entered.

• A freely formatted data structure has been developed which can be

used for phase diagram, crystal structure, lattice parameter, and

thermodynamic data. A preliminary report on the high level computer

language (LISP) based structure was made at the Computer Calculation

of Phase Diagrams (CALPHAD) conference (May 1982).

• Evaluation of Ti-systems has been continued. All Ti-transition and

Ti -noble metal systems will have been completed by September 30, 1982

and the evaluations published together as a report to the Office of

Naval Research.

• Two major new systems of A1 -binary alloys and Fe-binary alloys have

been initiated. The systems Al-Li, Al-Be, Al-Mg, and Al-Zn have

been completed. The systems Al-Cd, Al-In, Al-Ga, Al-Cu, and Fe-Ru

are in progress.

• Development of predictive modeling has been vigorously pursued.

Updated thermodynamic software have been obtained from the Stuttgart

group and necessary modifications to the user interface are underway.

Dr. Bo Sundman of the Royal Institute of Technology, Stockholm,

will visit our data center in November 1982 to provide us with

computer programs to use sublattice models.

• The feasibility of predictive modeling of metastable phase regions

has been demonstrated. Systems of interest for rapid solidification

processing which have been modeled are Ti-Fe, Ti-Co, Ti-Ni, Al-Mg,

Al-Li , and Al-Zn.

564-8
• Technique to produce very low oxygen (< 250 ppm) content Ti alloys

was developed to resolve conflicting reports of several Ti phase

diagrams in the literature.

• A Differential Scanning Calorimeter (DSC) was obtained to enhance

the experimental capabilities. This apparatus will be used as a tool to accurately determine transformation temperatures and heats

of transformation in Ti-Al-Mo phase diagrams.

• Ti-Al edge of the ternary Ti-Al-Mo diagram has been mapped, using

TEM, magnetic susceptibility, and DSC techniques.

• Alloy tempers and plate thicknesses that are most likely to contain

soft spots due to specific processing errors for 2024 aluminum

plates have been delineated.

• A model to predict macrosegregation in ingots of 2024 aluminum

alloy was developed and its usefulness to predict macrosegregation

in laboratory ingots of 2024 aluminum alloy was demonstrated.

• A set of experimental C-curves was determined from which the alloy

properties can be established for any time-temperature cycle during

quench from solution annealing treatment.

• Fundamental understanding of the relative solid solubility of two

transition metals has been advanced.

• A new understanding of volume effects in transition-metal alloying

has been provided.

The results of our metallurgical research are communicated to the scientific community through technical publications, lectures, active participation of Division members on various national and international committees,

personal contacts, and the organization and sponsorship of conferences

and meetings on various subjects such as acoustic emission, synthetic

implants, alloy phase formation, solidification, wear, and mechanical

failure prevention. For example, the personnel in the Division serve on numerous ASTM Committees, including Chairperson of the B-6 Committee,

Chairperson of Committee G-2, and Past Chairperson of Committee E-42,

and chairperson of several subcommittees. The staff participated on a number of National Materials Advisory Board (NMAB) studies including

Chairperson of the Rapid Solidification Processing Committee. The

technical staff have organized and chaired several international conferences on NDE, Wear and Processing. For example, the Third Conference on Rapid Solidification process to be held at NBS in late 1982 will be

chaired by our staff. The Metallurgy Division's staff serve on over 60

other national professional and technical committees.

The Metallurgy Division also acts as coordinator of a variety of industry/

academia/Government workshops. It coordinated and co-sponsored with

Committee on Materials (COMAT) the 1981 Briefing/Workshop on Rapid

Solidification Technology, with the proceedings being published as an NBS report in FY82. In July 1982, a Briefing/Workshop on the development

of process control sensors for the steel industry was organized and

convened at NBS.

564-9
The Metallurgy Division's programs also include direct contributions to

industry through the NBS Research Associate Program. Extensive interaction

with universities exists through the Cooperative Education Program, NBS

Postdoctoral Program, and faculty guest workers. Considerable interaction

also exists with other Government agencies, standards organizations, and

the technical community at large. For example, the Division performs

research for the following Government agencies: the National Aeronautics

and Space Administration, the Office of Naval Research, the Defense

Advanced Research Projects Agency (DARPA), the Department of Energy (DOE),

the Naval Ship Research and Development Center, and the U.S. Army Materials

and Mechanics Research Center.

564-10
STRUCTURE CHARACTERIZATION

Task 12142 and

SYNCHROTRON RADIATION RESEARCH FOR MATERIALS SCIENCE

Task 51105

Innovative processing techniques are being developed to produce significant new microstructures and structural /property relationships. Coupled

with increased industrial emphasis on quality control and automation,

these advances require a wide range of microstructural characterization

and nondestructive evaluation methods. The objectives of this task are

to address this challenge through the development of measurement methods

(including nondestructive techniques) and standards for the advanced

quantitative characterization of metallurgical microstructures. These

developments would permit automatic control methods for manufacturing

and in-service use of industrial alloys. Methodologies include x-ray,

optical and electron microscopy, eddy current, magnetic particles,

electrical conductivity, acoustic emission, and ultrasonic methods.

A new competence program in Synchrotron Radiation was initiated in FY80

as a part of this task. The availability of intense, tunable, welled limated radiation at synchrotron radiation facilities will permit

radical gains in experimental and theoretical materials science. As a joint NBS/NRL effort, we aim to establish an x-ray instrumentation

complex at the NSLS and to use it to perform frontier experiments in

transformations in materials, kinetic studies, furtherance of x-ray

optics, and the study of inner shell dynamics. One intermediate-term

goal of this effort is to establish an advanced x-ray analysis capability

at BNL and to apply this to the topographic analysis of cracks in a stressed metal alloy and to glass-crystal metal alloy transitions.

As part of our FY82 Metals Processing Initiative, new laboratory facilities were established for quantitative microscopy, ultrasonic scattering,

and acoustic emission. In the microscopy area, a TEM and a Quantimet

have been added, and a SEM is upgraded with energy dispersion spectroscopy

(EDEX). In the NDE area, new capabilities such as an interferometer, a computer, and other new ultrasonic equipment were added.

This group's accomplishments in FY82 are in two major areas:

1. A competence program of the application of synchrotron radiation to

materials science, in which this group in the Metallurgy Division

o o is taking a lead in the construction of hard radiation (0.5 A to 5 A)

branch lines at the NSLS in BNL for CMS and NRL scientists to

perform unique experiments for research problems in materials

science.

2. A new initiative for metals processing, where our group's effort

lies in the improvement of microstructure characterization facilities.

• The assembly of the CMS Synchrotron Radiation Beam Lines at NSLS in

BNL, which include two monochromator tanks, two hutches (experimental

stations for small angle scattering and real-time topography), and

beam transport mechanisms.

564-11
• The establishment of a new x-ray analysis capability in one of our scanning electron microscopes as part of the new initiative effort

for metals processes.

• The establishment of a new four megabyte capacity minicomputer for

analysis of varieties of data ranging from acoustic emission signals

to predictive modeling computation of phase diagrams.

• The establishment of a new laser interferometry for microstructure

characterization by acoustic emission.

• The establishment of white radiation topography techniques and an initial application to the characterization of Czochralski grown

Fe-Al crystals, Ni crystals, A1 and Sn powders, A1 polycrystals,

NaCl crystals, electron beam melted Si crystals, A1203, 2024 A1

,

and human teeth.

• The development of second generation charged-couple-device image

intensifies for real-time topography.

• The routine operation of in-house focused EXAFS and SEXAFS for

various amorphous materials such as metallic glasses and ultra-thin

passive films on metals and alloys.

Other programmatic goals of this task are to quantitatively evaluate

acoustic emission in steels and aluminum alloys and to compare the data

with theory, and also to develop ultrasonic spectroscopy so that it can

be effectively used in microstructural characterization and quality

control of defects during the processing and use of structure alloys.

Another effort includes both the microstructure characterization studies

through ultrasonic measurements and the monitoring of melting and solidification events during surface modification by AE. Other efforts are aimed at developing new eddy current standards and electrical conductivity

measurements, and in placing established techniques such as the magnetic

particle method on a more quantitative and reproducible basis. The

National Measurement Laboratory (NML)-Scanning Electron Microscope

facility is also located in this task. This facility not only serves on-going research efforts, but is also used in the development of standard

reference materials for SEM.

In connection with our program objectives, the Metallurgy Division has

sponsored a workshop on process control sensors for the steel industry

jointly with the American Iron and Steel Institute and the Defense

Advanced Research Projects Agency. The aim of this Briefing/ Workshop

is to first provide industry, university, and Government scientists and

engineers with the specific Process Control Sensor needs of the steel

industry; and secondly, to seek immediate input and future research and

development involvement from a broad spectrum of disciplines to facilitate

development of the sensors.

Finally, new programs were initiated in coupling of the nondestructive

evaluation program to rapid solidification processes as well as cooperation with The Johns Hopkins University and University of Maryland. In

564-12
association with the rapid solidification process program, a new contract

was established with DARPA.

Under this competence program which started in FY80 and a new initiative,

research collaboration was established with many scientists. Simon C. Moss,

Professor of Physics, University of Houston, has remained as consultant

for this year. Through the U.S. /France International Cooperative Program

of Materials Science, Z. Baran, Professor of Physics, University of Paris V,

has joined our group as a guest worker. This program for synchrotron/x-ray

topography was initiated in 1980 (see 1980 Annual Report) by the participation of an NBS scientist in collaboration with the National Science

Foundation. We have maintained close collaboration with Professor

Haydn Chen, University of Illinois; Professor Ronald W. Armstrong,

University of Maryland; Professor Robert E. Green, Jr., The Johns Hopkins

University; Professor Barton Roesslor, Brown University; Professor Yi-Han Kao

and Mr. Allan Goldman, State University of New York (Stony Brook); and

Dr. K. C. Yoo, Guest Worker from the University of Maryland; to perform

experiments. Several international collaborations have been maintained

and initiated and others have been with Professor H. J. Queisser and

Dr. W. Hartmann, Max-Planck Institut fur Festkorperforschung, Stuttgart,

Germany; Professor G. Hildebrandt, Fritz-Haber Institut der Max-Planck

Gesel lschaft, Berlin, Germany; Dr. J. Chikawa, Broadcasting Science

Technology Laboratories, NHK, (Japan Broadcasting Corporation) Japan;

and Professor T. Imura, Nagoya University, Japan; on the development

of real-time imaging in x-ray topography. Two distinguished visiting

scientists were actively involved in the activities of this task during

FY82. They were: Dr. M. Rosen of Ben Gurion University, Israel, and

The Johns Hopkins University, Baltimore, MD, and Dr. H. N. G. Wadley of

the Atomic Energy Research Establishment, Harwell, England.

The task is divided into subtasks whose activities and accomplishments

over the past year are described next.

Synchrotron Radiation Research for Materials Science

Task 51105, and

Application of Synchrotron Radiation to Material Science

Subtask 1 of Task 12142

M. Kuriyama, W. J. Boettinger, G. G. Cohen, R. C. Dobbyn, R. D. Spal , and

H. E. Burdette

As the Center for Materials Science's part of the NBS/NRL synchrotron

radiation research program at the NSLS, a group in the Metallurgy Division

o o has taken a lead in the construction of hard radiation (0.5 A to 5 A)

branch lines so that CMS and NRL scientists can make use of unique synchrotron radiation characteristics, such as high flux and tunability, for

research problems in materials science. The beam lines include facilities

for real-time topography, small angle scattering, interface/inelastic

scattering spectroscopy, and crystallography. Scientific problems are aimed at advancing materials science by utilizing techniques which were previously impractical. For example, the high flux in the synchrotron

beam makes possible the observation of local phenomena in materials in

564-13
real-time. The energy and momentum resolution can be made extremely

good so as to increase the precision in the determination of the atomic

coordination and arrangement. Furthermore, the tunability of the radiation

for the desired energy band pass enables us to focus on a particular

atomic species (elemental tunability) for the precise determination of

behavior under the influence of neighboring atoms in different local

volumes. The ultimate goal in materials science would be the formation

and verification of discrete atomistic theory for rates of phase transformation and structure stability. In approaching this goal, we have

placed an emphasis in the initial phase, on the development of dynamic

i n situ measurement capability to obtain an advanced knowledge on the

kinetics of microstructural transformations, and investigations of

short- and long-range order in various local volumes.

For the development of our synchrotron radiation beam lines at NSLS,

simultaneous activities are required in the four areas: (1) overall

beam line design; (2) new x-ray diffraction configuration, including the

development of prototype instruments; (3) monochromator/experiment

designs; and (4) computer control. Our basic philosophy for the CMS

experiments is to deliver x-ray monochromatic photons of energies between

5 keV and 30 keV by the simplest method and to create a high degree of

energy, momentum, and spatial resolution, primarily through flat crystal

diffraction optics. The beam is to be transported through Be windows

(10 to 15 mils thick) in an atmosphere of He. During the past 2.5 years,

we succeeded in achieving all goals in these four areas with the aid of

both a 12 kW high intensity rotating anode x-ray source and a synchrotron

radiation source at Cornell University (CHESS). We have entered into

Phase III, in which scientists are now working more frequently and

regularly at NSLS than at NBS.

A trailer has been purchased at the site of NSLS to be used as a small lab

for the preparation of our experiments at the beam lines. This trailer is

necessary because there is not enough working space in the beam line area. We have also established an account at NSLS to cover costs associated with

setting up the beam lines and performing experiments. Two monochromator

tanks and a beam transport port, which were constructed by the NBS machine

shops, are now being assembled at NSLS and being connected to experimental

hutches. The CMS synchrotron radiation beam lines will be completed by

the end of summer upon the completion of the front end, which will be

provided by NSLS.

To make the synchrotron radiation activity more effective, we have

carried out several experiments, independent of the beam line construction

using our in-house EXAFS experimental capability and CHESS synchrotron

radiation. Our in-house EXAFS experimental capability, which was established through our prototype development for the synchrotron radiation

program, is now in routine operation. This capability, unique in the

field of EXAFS, features automatic focusing with tunable energies of the

incident x-ray beam from 5 keV to 25 keV. This system is completely

computer controlled and data are analyzed automatically on site. This

new system has stimulated interest among many scientists; we are now performing EXAFS experiments on catalysts, layered thin films, oxides,

surfaces of thin films, Ti-compounds , metallic glasses, and biological

564-14
samples with Dr. D. Peterson, Dow Corning; D. Denley, Shell; W. Gibson,

SUNY/Albany; W. Wagner, Bell Laboratories; and Y. H. Kao, SUNY/Stony

Brook. This in-house EXAFS system has also been used by NBS scientists

in other centers in collaboration with us. The EXAFS technical activities

in our Division are described later. Using synchrotron radiation at

CHESS, we have explored a white radiation topography technique on both a stationary -and a real-time basis, and we have applied it to various real

materials including industrial alloys and human teeth (collaboration with

the American Dental Association). We have also performed monochromatic

radiation topography as developed in the past years [1,2] (See 1981

Annual Report) and made an initial effort of establishing quantitative

microstructure characterization involving detailed structural modeling

or the mapping of strains within a sample.

To summarize the present status in this CMS synchrotron radiation program,

we have begun assembling beam transport, experimental hutches, and mono- chromators at NSLS. Our prototype experiments for testing new x-ray

optical methodology have now been expanded to develop methods for the

future application to quantitative microstructure characterization. In

connection with these activities, we were invited to write a review

article on synchrotron radiation topography for the Annual Review of

Materials Science [3]. Some highlights of our technical activities in

the CMS synchrotron radiation materials science program are described

later in more detail.

[1] Kuriyama, M. ; Boettinger, W. J. Application of synchrotron radiation

to materials science. Annual Materials Research Society Meeting,

Boston, MA. 1981, November 16-19.

[2] Boettinger, W. J. ; Dobbyn, R. C. ; Burdette, H. E. ; Kuriyama, M. Real-time topography with x-ray image magnification. Nucl. Instrum.

Methods, 195: 355; 1982.

[3] Kuriyama, M. ; Boettinger, W. J. ; Cohen, G. G. Synchrotron radiation

topography. Annu. Rev. Mater. Sci. 12: 23; 1982.

Initial Development of Real-Time White Radiation Topography

Subtask 2 of Task 12142

W. J. Boettinger, H. E. Burdette, R. C. Dobbyn, and M. Kuriyama

X-ray topography is a nondestructive technique to image certain types of

metallurgical and ceramic microstructure from the surface or through the

thickness of samples under Bragg diffraction conditions. Depending on the wavelength of the radiation and/or the perfection of the crystalline

samples, the depth of material observed can range between 1 pm and 1 mm. Topographs are obtained for the detailed interpretation of images produced

by x-ray diffraction by real crystals. There are many situations, however,

where such a detailed study is neither required nor possible. Because of

the wide variety of materials and microstructures of interest in materials

science, a simple and rapid method for data collection is desirable. One

such method is white radiation (Laue) topography, which is particularly

suited to the early detection of a crystal grain newly formed from the melt.

564-15
The direction and magnitude of dislocation vectors, or the determination

of active slip systems can readily be obtained from a Laue pattern

containing different diffracting planes simultaneously.

White beam synchrotron topography requires only three optical elements:

the source, the sample, and the detector. The method is the same as the

Laue reflection or transmission methods commonly used for crystal orientation. The sample is placed in the white synchrotron beam and a Laue

pattern is recorded either on film or on a phosphor (for real-time

observation) viewed by a TV camera.

Each Laue spot contains the fine structure of a topograph as shown in

figure 1. Grains of arbitrary orientation are imaged because the sample

itself selects the appropriate wavelength to locally satisfy the Bragg

condition. Accurate positioning and orientation alignment are not

required. There is no need for scanning, and data can be obtained from

several Laue spots simultaneously yielding information at different

x-ray wavelengths. Of course, there are serious shortcomings in this

technique. However, depending upon the microstructures of interest,

this is the easiest technique to implement. (In terms of defect analysis,

however, it is probably the most complex.)

We have applied this technique, using synchrotron radiation at CHESS, to

various materials for different objectives [4]. A typical synchrotron

radiation white beam Laue photograph (a set of topographs) is shown in

figure 1, which was taken from a Czochral ski-grown Ni crystal in the

transmission geometry. This crystal contains several subgrains. At a quick glance it is easily recognized that the position of the oval

shaped subgrain in various Laue spots shifts around the central spot,

indicating the orientation (rotation) of this subgrain relative to the

major grain. This demonstrates a typical merit of white beam topography

for a quick and over-all assessment of microstructures. Even residual

stress effects can easily be detected as shown in figure 2. This is a Laue set of synchrotron white beam transmission topographs of a Si

crystal, which contains a spot created by an electron beam on the (111)

surface. This spot was melted by the electron beam and resolidified.

The residual stress pattern extends outward from the weld spot.

Another benefit of synchrotron white beam topography is the applicability

to almost any sort of solid, including industrial materials, as shown in

figures 3 and 4. Figure 3 shows a few examples of topographs obtained

from Laue spots of an A1 powder. A1 powder particles were solidified

with large undercooling, which made each particle single crystal-like.

These topographs immediately indicate whether these particles are a single crystal with a single nucleus or two grains. Also, information

is obtained as to whether these grains are deformed by strains, although

particle shapes are visibly spherical. Figure 4 demonstrates microstructures in a so-called single crystal turbine blade.

An enlarged view of a white beam topograph, figure 5, of a Fe 24 at. %

A1 alloy shows dumb bell images of inclusions. These inclusions are not

visible optically. This topograph also indicates the exi stance of other

imperfections, prompting a more detailed study of this crystal by mono- chromatic radiation topography, as shown in figure 6. This is a typical

564-16
representation of the effective use of white radiation topography; that

is, it is a rapid assessment of crystal microstructure leading to a more detailed research.

[4] Kuriyama, M. ; Boettinger, W. J. Applications of synchrotron radiation

to materials science. Materials Research Council (DARPA), Summer

Meeting, LaJolla, CA. 1982, July 6-7.

Quantitative Analysis of Strains Within a Crystal by Monochromatic

Radiation Topography

Subtask 3 of Task 12142

K. C. Yoo, R. C. Dobbyn, and M. Kuriyama

The work hardening which occurs at hardness impressions is considered to

be a major factor in determining the microhardness properties of single

crystals or of individual grains within polycrystalline materials. For

example, the orientation dependence of the crystal work hardening determines the level of microhardness pressure and hardness anisotropy which

is measured for different directions of the indenter axes of Knoop or diamond pyramid impressions. The pressure and anisotropy are critically

dependent on how a particular set of slip systems is activated by microhardness indentations.

As an initial attempt to develop a quantitative method of analyzing

local strains within a crystal by x-ray topography, we employed a real

time topographic system previously developed [5] (See 1981 Annual Report)

with a second generation image intensifier (See 1982 NDE Annual Report)

to the characterization of hardness indentations in a NaCl crystal and a copper crystal, using synchrotron radiation at CHESS.

First, we have demonstrated the possibility of observing in a continuous

way how these slip systems develop on a real time basis. Secondly, we obtained a series of topographs as a function of x-ray glancing angle,

while the whole sequence was recorded on a video tape, to confirm the

prediction of image contrast inversion [6]. This kind of experiment has

been impractical or impossible with laboratory x-ray sources. Figure 7

shows x-ray optical arrangement for changing glancing angle 6-

n as well

as an 044 topograph of NaCl at 0-

n = Bragg angle. Images around indentation impressions were analyzed in a similar fashion to a previous work

on Cu [7] for the determination of active slip systems and slip directions.

We also obtained a series of topographs from a Cu crystal with Knoop

indentations as a function of 0^ as well as 0

Qut (observation angle),

as shown in figure 8. This set of topographs is required for detailed

(quantitative) information on strains associated with indentation impressions. Without synchrotron radiation, it is impossible to obtain such a series within a realistic time frame. This approach, in a general line

broadening context, opens up a new avenue of characterizing imperfections

locally and quantitatively in terms of dynamic structure factor which

contains local atomic displacements.

564-17
[5] Boettinger, W. J. ; Dobbyn, R. C. ; Burdette, H. E. ; Kuriyama, M. Nucl. Instrum. Methods, 195: 355; 1982.

[6] Kuriyama, M. ; Cohen, G. G. Z. Naturforsch 37a: ; 1982; in press.

[7] Yoo, K. C. ; Roessler, B. ; Armstrong, R. W. ; Kuriyama, M. Scr.

Metal 1 . 15: 1245; 1981.

Structure of Nickel-Phosphorus Metallic Glasses

Subtask 4 of Task 12142

G. G. Cohen, M. Kuriyama, and A. J. Goldman

Fourier transforms of EXAFS data have been used to study the positions

of atoms surrounding the Ni atoms in glassy Ni-P. The structural analysis,

which was carried out as a function of processing parameters, was used

to show that at least two local configurations exist for a given metal -tometalloid composition.

When amorphous alloys are annealed far below the crystallization temperature, structural changes (i.e., "relaxation") and concomitant changes in

density are often seen. This process is probably continuous in some cases [8]. The present measurements, however, indicate that in the Ni-P

case, at least two metastable states exist for a single composition.

EXAFS spectra have been obtained for dc plated and pulse plated glassy

Ni 75^25 samples and for polycrystalline Ni 3

P powder, as well as for pure

Ni foils. Backscattering amplitudes and phases were determined for

Ni-to-Ni and Ni-to-P using the latter two samples as standards. Theoretical

curves were also obtained using parameters obtained (or interpolated)

from Teo et al . These calculated curves indicated that the measured

spectra are dominated by the Ni to P distances, and were used to demonstrate

that the pulse plated sample distances were stretched by 0.01A as compared

to the crystalline Ni 3P and the dc plated samples (which were the same within experimental error).

These results are in agreement with recent Mossbauer measurements [9] on similar samples and with published density results. However, none of

the earlier methods could probe the radial distances directly, and that

has been accomplished here. The EXAFS results can be taken as complementary to the other techniques, and as adding a new dimension to structure

determination in amorphous materials.

[8] Teo, B. K. ; et al. J. Am. Chem. Soc. 99: 3854; 1977.

[9] Lashmore, D. S. ; Bennett, L. H. ; Schone, H. E. ; Gustafson, P.

;

Watson, R. E. Polymorphism of nickel-phosphorus metallic glasses.

Phys. Rev. Lett. 48: 1760; 1982.

564-18
Structural Study of Passive Films on Iron

Subtask 5 of Task 12142

6. G. Cohen, D. R. Black, and M. Kuriyama

The first application of the surface EXAFS (extended x-ray absorption

fine structure) technique to the structure of thin (< 3 nm) passive

films on iron was carried out in a joint effort between the Materials

Chemistry and the Metallurgy Divisions of CMS.

o The samples were 50 A thick vapor-deposited Fe films on glass, which

were passivated by either a chromate or a nitrite passivating solution.

Near edge and extended x-ray absorption fine structure spectra were

measured on these films, as well as, on bulk Fe, and on an air-exposed

film.

The energy position of the K-edge discontinuity of a material is a function of the effective charge and the electronic configuration of the

absorbing atom. The edge shift of the chromate-formed film was 5 eV

lower than either the nitrite-formed film or the air-formed film (which

were within 2 eV of each other). This indicates a significantly lower

coordination charge for the chromatic-formed film and a likely greater

covalency in the bonding of the iron in this film.

The K-edge discontinuity is sometimes accompanied by a "white line," or

a strong enhancement of the absorption coefficient, in the region within

50 eV of the edge. The white lines indicate an empty or partially empty

state of p-character near the edge, which can be traced to the formation

of excitation levels or to a high density of states embedded in the

continuum. As is usual for a transition metal element, there is no white line in the K- absorption spectrum for Fe metal. Enhancements in

the absorption coefficient are clearly visible in the nitrite-formed and

in the air formed films, but are suppressed in the chromate-formed film

(fig. 9).

The EXAFS data was Fourier transformed to obtain the radial distances

about the Fe site. A comparison of the first neighbor and the second

neighbor coordination shells can be used as a measure of "the relative

disorder in a material." It was found that the air-formed film exhibited

the most order (crystallinity) and the chromate-formed film the most

disorder, while the nitrite- formed film was intermediate between the

two. This suggests that the passive layers in the chromate- formed film

are arranged in a more glass- like structure about the Fe atoms. The

Fourier transform of the chromate-formed film data is shown in figure 10.

Attempts were made to examine the structure around the Cr atom in the

chromate-formed film since many workers have found Cr in such films. A

lower limit of at least 12 percent Cr was found in the film, and an analysis of the structure is underway.

It is intended to study the breakdown of passivation next, and therefore

we also examined a chromate-formed film that had been exposed to a chloride solution for about one hour. Although no change was seen in

the position and shape of the K-edge for this sample, the same alteration

in the radial distances can be detected at this level.

564-19
Earlier attempts to determine the nature and structure of the passive

film on Fe, such as electron microscopy, Auger, and ultraviolet photoemission spectroscopy, have required ex situ examination of the passive

layer in a vacuum environment. This environment could alter the structure of the film by, for example, removing water from the samples. The

work 'described above provides structural and compositional information

on the passive film in a non-vacuum environment, and also yields information on the electronic configuration about the metal site.

Development of a Surface EXAFS Chamber and a High Resolution Analysis

Techni que

Subtask 6 of Task 12142

G. G. Cohen and D. R. Black

Following along the lines suggested by Fischer and Shevchik [10] a band-pass ionization chamber surface-EXAFS chamber was built, and is

undergoing further development [11]. This surface chamber operates with

the sample in an He environment and serves to collect the fluorescence

signal over a full hemisphere (271 steradians). It is estimated that

more than an order of magnitude is gained in sensitivity through the use of this device. It currently is computer controlled, operating through

a high sensitivity pi coammeter and rapid A-to-D converter. We estimate

o the lower limit of sensitivity to be a 10 A film, limited by the present

level of signal-to-noise. Samples of metallic glasses of FeB and FePC were first measured with this device, and the results compared to P diffusion data from the same samples. A high-resolution curve fitting

technique was developed to study the second-neighbor shoulder with good

resolution in the Fourier transform. Until now, few EXAFS studies in

the literature can resolve the higher order coordination, which is now routine in this laboratory.

[10] Shevchik, N. J. ; Fischer, D. A. Rev. Sci. Instrum. 50: 577; 1979.

[11] Fischer, D. A.; Cohen, G. G. ; Shevchik, N. J. J. Phys. F 10: L139;

1980.

Scanning Electron Microscope

Subtask 7 of Task 12142

D. Ballard

We continued the service and maintenance of the NML-SEM facility and

support equipment to satisfy the needs of NML personnel for electron

microstructure examination of materials involved in research activities

at NBS. Thirty-six hours of individual instruction on the operation and

techniques of scanning electron microscopy were provided to five NML

personnel

.

The SEM was used to measure the diagonal indent length on Micro Hardness

Conversion Blocks of a round robin test sponsored by ASTM E04.05. The

measurements were made on SEM photographs whose magnification was accurately

calibrated by use of the NBS-SRM 484 (SEM magnification standard). In

564-20
addition, a review of the Knoop indent images indicated that for best

overall illumination, the long axis of the indent should be perpendicular

to the SEM scintillator axis and at 0 tilt with respect to the 10 kV

electron gun beam. The increased resolution of the SEM above that of

the optical microscope revealed defects within the indents that could

lead to erroneous values particularly for the 25 g loads, l’.e., specimen

porosity ,. pol i shing scratches, diamond surface defects, and off-axis

indent impressions.

The last sample of SRM-484b was issued to fill orders received prior to

April 1982. At the present time, OSRM has 16 requests on back order.

Work has begun on the next issue of 150 units designated SRM-484c.

Present plans include calibration of the new units by use of a high

resolution SEM under computer control and a laser interferometer measurement output system. Use of this instrument, located in the Mechanical

Production Metrology Division, should provide improved accuracy and

shorter turn-around time for unit calibration. The SRM-484 is now referred to in part of MIL Specification # 883-B as the control standard

used in the measurement of integrated circuits by the SEM.

Several different carbon fibers were investigated in an effort to satisfy

the specimen criteria necessary for application of the proposed ASTM

Standard Practice for SEM Performance Characterization. The results

of observation on some of the carbon fibers will be presented and published

in the EMSA Proceedings 1982, Sputter Coated Carbon Specimens for SEM Perfor- mance Testing, by D. R. Black and D. B. Ballard.

The basis of the performance test is to measure the horizontal offset of

a recorded waveform produced as the electron beam scans across a welldefined edge of a suitable material. The resultant waveform is a product

of the electron beam parameters and its interaction with the specimen.

A low Z element such as carbon may not be the optimum material due to

electron beam spread and penetration. In view of this, several metals

and edge preparation techniques are being studied as possible candidates

for production of a satisfactory SRM.

Part of the investigation of the Kansas City Hyatt Regency Walkway

Collapse included SEM fractographic analysis of the failed weld areas of

the fabricated box beams and fractured washers of the suspension structure. The result of the SEM fractographic analysis was included in

NBSIR-82-2465 report.

Contactless Laser Generation and Optical Interferometric Detection of

Ultrasonic Waves

Subtask 8 of Task 12142

H. N. G. Wadley, M. Rosen, S. Fick, F. Nadeau, and R. Mehrabian

Transient loads applied by rapid energy transfer from a single-pulse

Q-switched high-energy laser generate compressive stress waves that

propagate in a material. Propagation of ultrasonic waves in a medium

cause surface displacements that can be measured optically by exploiting

the phase shift of an optical beam reflected from the surface of the

material. When the reflected beam is approximately combined with a

564-21
reference optical beam, from a helium-neon laser, phase changes are converted into amplitude changes, detectable by a suitable photodiode.

These amplitude changes are proportional to the surface displacements on the specimen. Potential problems arising from the fact that phase

changes also result from relative motion among the optical components of

the system, and even from fluctuations of the ambient air, are avoided

by appropriate features in the mechanical design of an interferometer.

An arrangement due to Fizeau is inherently compact and mechanically

stable, and thus well-suited to the present application. Two such

Fizeau interferometers can readily be combined so that the two optical

probes may be separated by a convenient distance to allow accurate

measurement of the travel time of an ultrasonic wave in the specimen

over a well-defined distance. Furthermore, the variation in magnitude

of the surface displacements detected by the two Fizeau interferometers

determines the ultrasonic attenuation in the specimen. This specific

system with dual Fizeau interferometers allows the simultaneous determination of both elastic-wave velocity and ultrasonic attenuation.

Compared with other sensors, interferometers offer several advantages.

The sensitive area is definite, and can be made as small as a few microns

in diameter for highly localized measurements. A known quantity, displacement, is measured; independent methods of absolute calibration are applicable which give small overall errors. Bandwidth, determining the

fidelity of reproduction of signal waveshapes, is limited not by the

physical nature of the transduction process but by its associated electronics. In this respect, performance can exceed that of conventional

piezoelectric transducers. Small signal resolution and bandwidth are related; displacements of a few angstroms are detectable at 7 MHz bandwidth. Laser loading produces a stress pulse of high amplitude and

short duration so that investigation of highly attenuating, or very

thin, specimens is possible. The noncontact feature of both generation

and detection of ultrasonic waves is advantageous in situations requiring

physical separation between the measuring system and the specimen.

Furthermore, the noncontact mode of generation and detections precludes

interaction with, and modification of, the wave propagation under study.

The two-channel, quadrature-dual laser interferometer developed and

constructed permits highly accurate sound wave velocity measurements of

longitudinal, transverse, and Rayleigh waves. From the absolute surface

displacement measurements, it is possible to determine the values of the

attenuation of these waves, as well as, their frequency dependence.

The contactless method of generation and detection of ultrasonic waves

permits dynamic measurements to be performed whereby the specimen is

subjected to programmed heat treatments, or is positioned in a hostile

atmosphere. The noncontact mode of generation and detection precludes

interaction or modification of the wave propagation under investigation.

This unique dual -channel laser i nterferometer is in the process of final

adjustment and calibration.

564-22
NDE Characterization of Thin Structurally Modified Surface Layers on Bulk Substrates

Subtask 9 of Task 12142

M. Rosen, F. Nadeau, and R. Mehrabian

Laser and electron beam irradiation techniques are being applied extensively for the modification of properties of the surfaces of metallic

structures. High intensity power transferred onto the metallic surface

produces a liquid pool that rapidly solidifies under the influence of the

chilling effect of the cold substrate. Formation of hard martensitic

layers, soft pearlitic bulk, solid solution strengthening of the peripheral

layer, grain size refinement, dispersion hardening, or formation of an amorphous layer on a crystalline substrate can be achieved by laser or electron beam heating. Of particular interest, from both technological

and scientific points of view, are the physical and mechanical properties

of the modified surface layer, as well as its dimensions. In most

instances, the thickness of the modified layer is not accessible to

nondestructive testing. However, the determination of the thickness of

a case-hardened steel shaft may be of prime importance for engineering

design. Similarly, in the case of amorphous glazing of a crystalline

substrate. The physical properties of the amorphous layer and its depth

may be important parameters for the evaluation of the efficiency of the

glazing process and determination of the strength of the modified layer.

Microstructural modifications in peripheral layers of bulk specimens was obtained by means of rapid heating and cooling with an electron beam.

Relatively thick amorphous layers (about 1 mm) were obtained on crystalline PdCuSi. In addition, martensitic and bainitic microstructures were produced on pearlitic steel plates. The NDE characterization is being

made by measuring the Rayleigh surface wave velocity. Therefore the

metallurgical characteristics and the thickness of the modified layer

can nondestructive^ be determined.

The essence of this research was to develop a technique by which Rayleigh

surface waves may be launched. The Rayleigh waves propagate within the

surface layer only or penetrate the substrate depending on the wave

frequency. The Fourier analysis of the frequency content of the Rayleigh

waves allows determination of the thickness of the layer provided its

elastic moduli differ by several percent from those of the crystalline

substrate.

Crystallization Kinetics Study of Amorphous Zr-Cu by Ultrasonic and

Microhardness Measurements

Subtask 10 of Task 12142

M. Rosen, F. Nadeau, and R. Mehrabian

Metallic glass formation and subsequent crystallization upon heating has

recently become an active research area. Rapidly solidified amorphous

alloys exhibit a variety of desirable physical, chemical, and mechanical

properties that are particularly attractive for products in electronics

and power industries. Moreover, functional and economic advantages may

564-23
be gained when crystallizing specific alloys into microcrystalline

structures that can be subsequently consolidated into bulk products.

Microstructural characterization using nondestructive techniques, e.g.,

ultrasonics, may thus be attractive both for its contribution to understanding the kinetics and mechanism of the transformation and for its

ultimate application for on-line feedback control of materials processing

variables.

Metallic glasses are not thermodynamically stable, and they tend to

structurally relax and finally crystallize upon appropriate heat treatment.

The activation energy for relaxation continuously increases with time,

which may correspond to the removal of quenched-in defects. Associated

with relaxation and crystallization are variations in the elastic and

mechanical properties. Young's modulus E and shear stiffness m generally

increase by 20 to 40 percent, but the bulk modulus K by only about

7 percent upon crystallization. The density of glassy metals is generally

only 0.3 to 1.5 percent less than the corresponding crystalline structures.

As-quenched glasses contract approximately 0.5 vol % during relaxation.

Straightforward elasticity and wave propagation theories enable one to

calculate Young's modulus E. For one-dimensional extensional wave

propagation in a homogeneous, isotropic, linearly elastic solid. Young's

modulus is given by E = Vr 2 /p where v

F is the extensional wave velocity

and p is density.

The Cu-Zr metallic glass ribbons were prepared using the melt-spinning

technique. A 2 mm wide, 30 mm thick ribbon was produced. Ultrasonic,

x-ray and STEM examinations indicated that the ribbon was completely

amorphous. The ribbons were heat treated in evacuated capsules at

temperatures above the glass transition point, Tg, for different time

intervals in order to obtain information about the crystallization

kinetics and its mechanism.

The objective of the present investigation was to study the crystallization kinetics of Zr-Cu ribbons (about 50 pm in thickness) by means of

laser-generated and piezoelectrically detected, ultrasonic waves whereby

the extensional wave velocity, and consequently the Young's moduli could

be determined as a function of crystallization time. The amorphous-tocrystalline kinetics could thus be determined to a high degree of accuracy.

The inherent difficulty of measuring sound-wave velocities in thin-ribbons

was overcome by developing a technique applying the load on the specimen

by means of rapid deposition of energy from a single-pulse of a Q-switched

Nd:YAG laser. A state of unbalanced compressive thermal stress is

produced. The stress gradient propagates along the ribbon in the form

of an elastic wave. The piezoelectric crystal, at a distance from the

spot where the last radiation was deposited, detects the local displacement. Thus, the transit time of the propagating wave could be determined

accurately by means of a transient-pulse recorder. In this work, ultrasonic extensional waves were detected using a National Bureau of Standards

conical PZT transducer having a flat response between dc and 2 MHz.

Signal amplification was provided by an EMI 6306 charge-sensitive amplifier

powered by an EMI Power Supply Type 6396. A silicon photodiode triggered

a Nicolet Explorer III digital oscilloscope so that the elastic wave

564-24
could be recorded and transit times read directly from the screen of the

oscilloscope. The transit times were determined to be better than 1

part in 104

, and the source-receiver distance to within +0.3 percent.

All velocity measurements were conducted at room temperature.

Small sections of each heat treated specimen were mounted in epoxy for

Knoop microhardness number (KHN) measurements. To minimize anvil effects

and to ensure that KHN values were taken of the bulk material, each

specimen was cut perpendicular to its length vector, and then was mounted

with its cut face exposed. After polishing the mounted ribbons to

0.05 pm alumina, KHN values were determined using a 10 g load and aver- aging four symmetrical indentations.

The structural relaxation and crystallization effects induced by isothermal

heat treatment on the room temperature ultrasonic extensional wave

velocity, Youngs' modulus, and Knoop microhardness of Cu-Zr ribbons are summarized below.

Velocity versus log-time curves exhibited isokinetic sigmoidal behavior.

Extensional wave velocity increased ~ 2.0 percent and Young's modulus by

4.0 percent due to structural relaxation. Young's modulus increased

43 percent upon transformation from the amorphous to the fully crystalline

state. Knoop microhardness increased to a relative maximum, equal to

44 to 88 percent of the asymptotic KHN value, during structural relaxation.

KHN then decreased to a minimum, due to stress relief annealing. The

final microhardness rise to an asymptotic KHN value of ~ 720 kg mm

-2 was

due to crystallization of a hard, brittle equilibrium CuZr phase.

Using data derived from the velocity versus log-time curves, the activation energy for 50 percent crystallization was found to be 360 kJ mol” 1 and the n parameter from the Johnson-Mehl-Avrami equation was approximately

unity. This value is consistent with one-dimensional diffusion-controlled

growth.

An as-spun ribbon contains many quenched-in defects so that the glass

may be viewed as having a continuous distribution of varying coordination

or excess free volume. Reduced coordination in given atom complexes

permits the material to undergo shear transformations without undue

constraint and results in a ductile metallic glass. Heat treatment

removes quenched-in excess free volume through structural relaxation.

The amorphous material thus approaches the ideal glassy state, having a rigid close-packed atomic distribution. Consequently, the glass should

harden and become less ductile in the relaxation regime. This behavior

was indeed observed in the present study. The main contribution to

hardness was attained during the relaxation of the amorphous phase.

Eddy Current Standards

Subtask 11 of Task 12142

A. J. McAlister

The eddy current method is widely used in both the ferrous and nonferrous

metals industries for nondestructive detection of flaws such as cracks,

inclusions, and variations in composition and microstructure in metals

564-25
and metal parts via local changes in electrical conductivity. Primary

conductivity standards are needed for reliable execution of this work,

but to date, this need has been supplied by industry itself. The neces- sary range of conductivity for industrial testing is from 0.585 to

58.5 MSm-1 (1 to 100 percent IACS).

The properties desired in a primary conductivity standard are long term

stability, durability, and low magnetic susceptibility. (In testing of

high susceptibility steels, normal practice has been to apply a saturating

magnetic field to reduce the differential permeability to a value near that of vacuum.) Hence, elemental metals and alloys of equilibrium

phase composition, upon which stable nonconducting surface layers can be

formed, are desirable. The surface properties are important not only

for durability, but for reproducible lift-off behavior as well.

Our overall aim is the selection of metals and alloys suitable for primary

conductivity reference standards, and the preparation of specifications

for their preparation and fabrication. Progress to date in this work is

summarized in the following table, in which target conductivity, material,

condition of the material as examined, observed conductivity and its extreme

variation over the sample faces, and status of the material are listed.

Summary of Conductivity Testing

Target Observed Conductivity

Conductivity and range

(% IACS) Material (w/o) Status Condition (% IACS)

101 OFHC Cu * annealed 101.9 + 0.1

* unannealed 99.5 + 0.2

85 1.3 Zn + Cu # as cast 81.1 + 0.4

75 2.4 Zn + Cu # as cast 70.4 + 0.4

60 A1 1100F + complete 60.0 + 0.05

48 A1 2024-0 + complete 47.0 + 0.1

41.5 A1 6061-T + complete 41.0 + 0.05

29 A1 2024-T-351 + complete 30.0 + 0.1

23 21.5 Zn, # as cast 20.5 + 0.3

2.5 A1 + Cu

17 7 A1 + Cu # as cast 15.6 + 0.1

17 6 Ni + Cu * as received 17.7 + 0.1

12 1.5 Si + Cu # as cast 10.1 + 0.2

7 3 Si + Cu # as cast 7.5 + 0.2

7 23 Ni + Cu * as received 6.11 + 0.01

3.5 Ti , Grade 4

* unannealed 1.95 + C. 05

3.5 45 Ni + Cu * as received 3.440 + 0.002

1.0 8 A1 , 1 Mo, * unannealed 1.07 + 0.007

IV + Ti 0.86 + 0.012

1.0 6 A1 , 4 V + Ti * unannealed 0.97 + 0.005

Status is indicated as: +, finished, calibrated standards; *, commercial

products

,

faced and examined; #, alloys cast in-house , faced and examined.

Production and calibration of the Al- based standards is complete.

564-26
Apparent conductivity variation over the surfaces of commercial alloys

appears random, and is taken to reflect the variation to be expected in as received condition. The better uniformity of annealed vs unannealed

Cu is due to the removal of cold work damage. Annealing did not improve

Ti or the Ti -based alloys. The major part of the conductivity variation

in the as cast Cu-based alloys is due to solute segregation upon solidification, and should be largely removed by homogenization.

The decision to focus on Cu-based alloys outside the A1 and Ti ranges,

and to prepare special melts, was not made lightly. As a practical

matter, it is essential that the magnetic permeability of an eddy current

conductivity standard be very close to the vacuum value. Only Cu-based

alloys are potentially capable of meeting this criterion in the needed

conductivity ranges. Special melts are indicated because current industrial practice is to add significant quantities of Fe, Co, and Mn (which

can develop full magnetic moments or form magnetic precipitates in Cu)

as grain refiners or to improve mechanical properties. Currently available Si-bronzes contain 0.8 w/o Fe; Cupro-nickel s , 1.0 w/o Fe; brasses,

0.05 percent Fe. Yet the brasses, for example, must contain less than

0.03 percent Fe if Fe precipitation is to be avoided during stress

rel ief.

In view of the importance of the magnetic properties, we have assembled

and tested equipment for the measurement of magnetic susceptibility by

the Gouy method. We are currently working on two sets of 100 coupons

each of oxygen frequency high conductivity (0FHC) Cu and Ti-6-4 alloy.

Acoustic Emission for NDE Survei lienee and Quality Control

Subtask 12 of Task 12142

J. A. Simmons, R. B. Clough, H. N. G. Wadley, and R. Mehrabian

Acoustic emission refers to a technique for the measurement of elastic

stress waves emitted by rapid dynamic changes of state in materials. AE can be used to detect, monitor, and measure the occurrence of plasticity,

cracking, phase transitions, and corrosion where they are accompanied by

rapid stress changes. Consequently, AE has unique potential as a passive

surveillance tool for the control of microstructure during materials

processing, monitoring fabrication of components and detecting, locating

and characterizing flaw growth in structures. It also promises to

provide a new tool for the quantitative measurement of the dynamics of

material changes of state.

The structure of the stress waves emitted during acoustic emission is

complex, and until recently the general formulism establishing the

relationships between stress change sources and the amplitude and temporal

character of the emission they provide was only poorly understood.

Recent work at NBS has addressed these problems. This work demonstrated:

• Existing measurement methodologies that have evolved to date make

use of only a small fraction of the potential information contained

in acoustic emission signals.

564-27
• The character of the emission will be controlled by synergistic

interactions between metallurgical variables and the stress state.

In spite of these difficulties, the technique is increasingly successful

in finding application for monitoring cracking and predicting failure in

ceramics, composites, and metal weldments. However, it also has the

potential to make a great contribution to the monitoring of metals

processing where it could provide essential data for feedback control

improving quality and productivity, but this has received scant study in

the past.

At NBS, a unique approach to the measurement of acoustic emission is

being developed which has as its objective reconstruction of the source

dynamics. This technique, which is similar to that currently revolutionizing the field of seismology, utilizes simultaneous high speed measurements (at different locations) of the initial wavefronts from individual

emissions to allow quantitative reconstruction of the source stress

drop. At least six observation channels are necessary for reconstruction

of the six stress drop components as a function of time. To implement

this advance in AE measurement methods:

• A computer based multichannel AE system has been constructed.

• New experimental methods for controlled generation of AE sources

developed.

• New theoretical techniques of forward modeling and inverse filtering

devised for signal analysis.

• Publication for deconvolution theory for multichannel experiments.

• Critical experiments will be carried for verification of multichannel

AE analysis using a Nd:YAG laser and plate geometry.

• Correlation of AE signals, microstructural analysis and thermodynamic

parameters of rapidly solidified electron beam source in aluminum

and an aluminum alloy.

• A set of critical experiments designed to establish the validity of

these new measurement methods.

Parallel studies drawing upon the above techniques, have examined flaw

growth as part of the joint NBS/EPRI program in AE and explored the use

of AE for monitoring rapid solidification as part of the DARPA/NBS

project in Rapid Solidification and NDE.

Our program during the past year can be broken down into four categories:

(1) Theoretical advances.

(2) Experimental verification of source characterization.

(3) Experimental method for the controlled generation of AE in

A533B pressure vessel steel.

(4) AE studies of rapid solidification.

564-28
(1) Theoretical Advances

The theoretical framework for acoustic emission sources rests upon

Green's function formalism for stress waves generated by changes in

internal stress induced when a source responds inelastical ly to structural

loads. The forward formulation, in which the emission from a source of

known character is deduced, has been published in Theory of Acoustic

Emission, Proceedings of the International Conference on Dislocation

Modeling of Physical Systems, Pergamon Press, 1981.

There the representation of an AE source event was first given in multipolar expansion form and then restricted by two assumptions, the pseudopoint approximation and the Stump- Johnson representation, to avoid the

technological difficulties associated with high moment components. The

key restriction for validating these assumptions is a band limiting

process to restrict the frequencies to a region called The Informative

Band. Estimates of the limiting frequency for the band were given as a function of defect size and shape. Within the informative bandwidth one

can develop a transfer function formalism which allows one to consider

transmission of the information frequency by frequency from the source through the structure to the detector: outside this band specific

models of the details of the AE mechanism are required to deduce AE

signals.

The general formulation of acoustic emission from plasticity, cracks,

and phase transformations was then developed within the pseudopoint

approximation using the concept of retarded dipole density to deal with

the problem of time delays from emission from propagating cracks and

phase change regions. The radiation patterns for defect sources are highly directional and depend on source type and orientation (see figs. 11

through 13). Finally, the concepts of stress controlled and materials

controlled acoustic emission were introduced and the synergistic relation

between the ambient stress field and microstructural contraints were

discussed.

Subsequent work has concentrated on the inverse problem for deducing the

character of the stress drop components from measured acoustic emission

signals. This is one of a class of "remote sensing" problems in which

small amounts of measurement error or noise can obscure the information

about the source signal. Sophisticated signal processing techniques are demanded.

The transfer function formalism leads to simultaneous convolution equations describing the acoustic emission signals in terms of the source

stress drop components, the structure response, and the transducer

characteristics. These simultaneous equations can be reduced to a single deconvolution equation which is, in general, even more illconditioned than deconvolution problems encountered in time series

appl i cations.

A singular valued decomposition (SVD) algorithm developed in conjunction

with D. O'Leary (Division 711), A Bi di agonal ization-Regulatizati on Procedure for Large Scale Discretizations of Ill-Posed Problems, SIAM

Journal of Statistics and Computing, December 1981, has been applied to

564-29
such signals. Since the full SVD algorithm is prohibitively demanding of

computer resources for problems of the type required in acoustic emission,

the above procedure uses a reduced dimension representation similar to

the Rayleigh-Ritz procedure. The SVD algorithm both inverts and filters

to produce a number of candidate solutions to the inverse problem. The

results obtained, while promising, suffer from the difficulty that it is

difficult to select the "best" approximation from among the candidate

sol utions.

To help deal with this problem and to examine the possibility for new pattern recognition techniques for source signatures, an alternate

approach is being studied. This approach uses a modification of the Z transform of the time series to be inverted which allows powerful complex

variable techniques to be combined with linear algebraic methods for

inverse filtering. In this approach the Z transform of the time series

becomes a polynomial of high degree (typically 512 or higher). An

entirely new set of algorithms has been developed which finds all the zeroes of such high degree polynomials and uses these for both pattern

recognition purposes and to develop new noise filters which are supplemental to those obtained in the SVD approach and can be used to greatly

reduce solution noise while allowing a priori information about the

frequency content of the solution to be factored in.

These new algorithms, which must be applied to time series of great

length to be usable in acoustic emission inversion, are currently being

employed to find rebust procedures for deconvolution. An example of the

types of candidate solutions obtained in carrying out deconvolution (in

this case of a 43-point time series based on the surface-to-surface

Green's function for a half-space) is illustrated in figures 14 through 20.

(2) Experimental Verification of Source Characterization

The objective of source characterization is measurement of the magnitude,

orientation and time dependence of the stress drop tensor of acoustic

emission sources. The stress tensor provides the basic information

required for defects assessment in NDE and, in the laboratory, promises

to provide dynamic information that would greatly advance our understanding of the dynamics of metal deformation and phase transformation processes

A formulism based upon dynamic elasticity has been developed which, in

principle, provides us with a framework for deducing the stress drop

tensor. Instrumentation to implement this approach has also been compiled.

Now, a critical series of experiments are underway in which the stress

drop tensor is to be measured using acoustic emission techniques and

compared with that independently deduced by measurement or predicted

from well developed theory.

The problem is that there are no available techniques for the measurement

of stress drops when they occur at velocities close to that of the speed

of sound. One possible approach we are following is to use reproducible

cracking under indentation loading and this is discussed below. However,

another possible approach is the use of a simulated reproducible acoustic

emi ssion.

564-30
The ideal simulated source should be composed of dipole forces of similar

magnitude and orientation to those of natural AE and have a time duration

between 10 ns and 10 ps (the range of the majority of natural emissions).

These properties should be predictable and/or independently measurable.

We have set up a laser generated thermoelastic simulated acoustic emission

source for critically evaluating the performance of multichannel source characterization.

The thermoelastic dilatational strain accompanying absorption of pulsed

laser radiation has been modeled as a combination of force dipoles whose

strengths were calculated using thermal diffusion theory. The temporal

behavior of the elastic displacements due to each dipole component were

then evaluated from the dynamic elastic Green's tensor for an isotropic

infinite plate. The displacement waveform for the complete source was

then obtained by linear superposition of the individual dipole responses.

The thermoelastic source generates longitudinal, transverse, and surface

waves. When calculations of displacement are performed on the same surface as the source, the waveforms are dominated by surface waves,

particularly at large source-receiver distances. When calculations are made on the surface of the plate opposite the source, the transient

displacement waveforms are dominated by head-waves. These latter waves

have a nonunique ray speed and would lead to ambiguous source locations

in acoustic emission monitoring.

Wide bandwidth response instrumentation system has been designed and

constructed that can measure displacement down to a sensitivity of ^ 10- 14 m over a 2.5 MHz bandwidth. This has been used to measure the

displacement waveforms from the thermoelastic expansion accompanying the

absorption of Nd:YAG laser pulses of 25 ns duration.

The measured waveforms contain the features predicted by theory and the

dipole magnitudes are, within experimental error, in agreement with

these predicted. From this encouraging basis we are proceeding to apply

the deconvolution procedures developed above to deduce the full tensor

description of the source stress change.

(3) Experimental Method for the Controlled Generation of AE in A533B

Pressure Vessel Steel

Here the objective, for the nuclear power industry, has been the development of an experimental technique for localized production of reproducible

AE signals (by indentation) in A533B pressure vessel steel and the

correlation of these signals with the defects and microstructure at that

location.

These steels, while in the normalized condition are nonemissive, can become embrittled and emissive during fabrication into nuclear reactor

pressure vessels by improper welding and heat treating practices (temper

embrittlement), and can be further embrittled during service due to

hydrogen, which is a fission product. Recently the NRC announced (Newsweek,

April 19, 1982) that 8 of these vessels in service are becoming

embrittled at a much faster rate than the originally expected 40 year

564-31
1 ifetime--down to a few years. It would seem that the above effects

could contribute synergistical ly with the normally present radiation

embrittlement and stress corrosion to reduce those lifetimes.

By controlling the tempering and hydrogen charging in A533B we succeeded

in producing AE from virtually none in the normalized condition up to an activity as high as that of borosilicate glass in the fully embrittled

condition. We were further able to relate the sources of emission as being due to microcrack nucleation 5 micron) at MnS inclusions (fig. 21)

in the temper embrittled state and growth to larger grain boundary

cracks 250 micron) with the addition of hydrogen. A very significant

result was the unexpectedly prominent role played by the MnS inclusions

in the temper embrittlement process, as opposed to the usual attention

given to segregated grain boundaries. This aspect is being followed up

by work at Harwell.

(4) AE Studies of Rapid Solidification

Rapid solidification is a new technique used for producing metallic

glasses, which provide low loss transformer core material, and it is

also used to produce superior surface coatings and long wearing bearing

surfaces. AE can be used to monitor rapid solidification surface modification to detect flaws produced during processing. It also promises to

provide dynamic information on the solidification process itself since a typical solidification time for a surface melt is on the order of 100 ms and stress waves can be monitored over considerably shorter times 100 ps)

Very little work has been done in this area and due to the potential of

AE to shed light on this subject, NBS and DARPA are sponsoring research

on AE monitoring of rapid solidification processing.

Because of its commercial applications in welding and surface modification,

the electron beam was used as a directed energy source for melting. A new technique has been developed for studying solidification of such

melts. First it was verified that the signals were not electrical noise

and were caused by material changes during solidification. The experimental

approach consists in irradiating a spot on a plate, producing a steady-state

melt at 2 x 10 5 Wm -1 for flex density/radius (qa) (the product of the

heat flux density and the source radius), switching off the electron

beam to eliminate it as an AE source, then monitoring the amount of

energy produced by AE during solidification.

Our first results show the effects of alloying on resolidification AE.

The resolidified melts in the 2219 aluminum alloy contained numerous

cracks which indicate that hot tearing during solidification is the cause of the AE in the 2219 alloy (fig. 22). In contrast, the 1100

aluminum resolidified melts had virtually no cracks (fig. 23). This is

reflected also in the amount of energy emitted acoustically during

resolidification for the two materials (figs. 24 and 25).

Results of this type are of great interest to the rapid solidification

field and these represent just the preliminary results. Once the sources

of AE in rapid solidification are more fully ascertained, steps can be

made to implement AE monitoring of surface modification processes. In

564-32
addition, once the sources of AE are ascertained, it is expected that

these can be used for dynamically observing the solidification process

and the kinetics involved.

Magnetic Particle Inspection Standards

Subtask 13 of Task 12142

L. Swartzendruber

This project was initiated by the Specification and Technical Data

Branch of the Army Materials and Mechanics Research Center, Watertown,

MA. Military Specification MIL-M- 11472, Magnetic-Particle Inspection;

Process for Ferromagnetic Materials, is being reviewed for proposed

revision or cancellation and replacement by Military Specification

MIL-STD-271, Military Specification MIL-I-686, or American Society for

Testing and Materials Recommended Practice E709-80. The contents of

these documents have been compared with current state-of-the-art practice

in magnetic particle inspection as revealed by industrial practice,

available literature, current applicable Military Standards, Aerospace

Materials Specifications, and American Society for Testing and Materials

documents. A draft version of a revised MI1-M- 11472 has been prepared.

Feedback from Department of Defense users will be used to eliminate or review portions as deemed necessary.

Magnetic Measurements

Subtask 14 of Task 12142

L. Swartzendruber

Nondestructive evaluation methods utilizing "magnetic leakage fields"

are widely used for detecting defects in ferromagnetic materials such as iron and steel. These methods involve the magnetization of the material

and the subseguent detection of the leakage fields resulting from any

defects which might be present. A common technigue for detection of

leakage fields is magnetic particle inspection (MPI). MPI involves the

spraying or flowing of minute magnetic particles over the magnetized

material. Patterns are formed on the surface which indicate the location

of surface or subsurface defects. This method reveals the presence and

location of defects, but gives limited information about their size,

shape, or depth below the surface. Other methods, such as measurement

with a Hall probe or moving coil, give more guantitative information

about the leakage field, but correlation of the measured field with the

shape and location of the defect also presents considerable difficulty.

In a material of constant permeability, analytical calculations for

various geometries, such as a long transverse cylinder, are possible.

We have previously shown that measured magnetic leakage fields above

artificial cylindrical defects in a steel sample are considerably larger

than the strength calculated analytically for a material of constant

permeability, however high that permeability might be. Clearly, the

nonlinear B-H relationship has a significant effect in this type of

measurement. Thus, any mathematical model of such a system which incorporates permeability as a constant is insufficient; permeability must be

564-33
incorporated into the model as a function of the field strength. This

complication necessitates numerical solutions which require lengthy

calculations for each specific case.

Utilizing a nonlinear finite difference method, and an analytical representation of the nonlinear B-H relationship, numerical calculations have

been performed on the Metallurgy Division computer. The numerical

method was used to calculate leakage fields for subsurface defects and

for slits open to the surface. For comparison, linear calculations were

also performed. These calculations were then compared with experimental

measurements. The nonlinear numerical calculations are in qualitative

agreement with the experimental measurements and confirm that: (1) the

leakage field perturbation due to the defect continues to increase well

into the saturation region of the magnetization curve; (2) the leakage

fields have a shape nearly that expected from a linear magnetic dipole;

and (3) nonlinearity causes the defect to appear closer to the surface

than its actual physical distance and stronger than predicted by a linear theory.

A critical factor in obtaining successful MPI results is the choice of a proper magnetizing level. Often it is assumed that, for the MPI technique,

the applied field strength at the point of maximum permeability should

be used as the field strength in order to yield optimum text results.

However, the correlation we have obtained, both experimentally and

theoretically, demonstrates that this is not a correct assumption.

Other factors, and not the maximum sample permeability, place an upper

limit on the applied field strength for optimum results.

Our results show that the magnetic leakage field continues to grow

nearly in proportion to the applied field out to very large applied

fields. The optimum applied field for MPI is thus the largest allowable

subject to other constraints. These constraints involve mainly the

effect of stray fields, i.e., fields which arise from end effects,

surface finish, etc. These stay fields have a number of deleterious

effects. They can, for example, cause the particles to be swept past

the defect at too high a velocity to be "captured" by the leakage field,

or they can cause particles to be attracted to the surface over large

areas, contributing to a background which can mask indications from real

defects.

Thus, we find that the value of the applied field in the vicinity of the

defect is more important than the magnetization level of the material.

This applied field can be effectively determined using a small Hall

probe, or other suitable field measuring device, located so as to measure

the component of magnetic field parallel to the sample surface and as close to the sample surface as possible. This has important consequences

for obtaining reliable and reproducible magnetic particle inspection

results, especially on parts which are not of simple geometric shapes.

The effectiveness of various methods of magnetization, current levels,

etc., can be readily assessed by easily made Hall probe measurements.
Development and Application of a Second Generation Image Intensifier for

Real Time Microradiography

Subtask 15 of Task 12142

M. Kuriyama, W. J. Boettinger, H. E. Burdette, and R. D. Spal

The resolution of real-time radiographic systems is often dictated by the

spatial resolution of viewing detectors. To overcome this difficulty, an x-ray image magnification technique was developed [12,13]. This development does not, however, negate any further improvement of the spatial

resolution of image detectors. As a continuing effort seeking a better

detector, we have employed a double intensified charge injection device

(ICID) camera to develop an x-ray image intensifier. This ICID camera is,

in effect, a modified solid-state charge-couple TV camera.

In general, there are two approaches to obtain optical signals from x-ray

photons: (a) direct photon-electron conversion in videcons; and (b) visible

photons converted from x-ray photons by a phosphor, and subsequently viewed

by an optical image intensifier. In this work, we chose the second approach.

Phosphors of different particle sizes were prepared on fiber optics plates

30 pm). The ICID camera was tested by a wedge-shaped resolution test

pattern after one of the fiber optics plates was mounted tightly in front

of the camera. Typical results are 2.9 line pairs/mm for FG3M phosphor

and 4.5 lp/mm for P20 phosphor (4.3 mg/cm2

) by visual test. The last

value corresponds to limiting resolution 110 pm.

To determine quantitatively the degree of resolution in this system and

determine quantum efficiency, another set of measurements was made using

this system with the two kinds of phosphors. The ICID camera was operated

in photon counting mode, that is, low flux, high gain mode. The image

output was digitally processed, using a video frame grabber and a digitizer

interfacing LSI 11/23. With the P20 phosphor, the order of 4 pixels in

radius per a single photon was observed. One pixel is 40 pm x 30 pm.

This result agrees with the visual result of 110 pm limiting resolution

(5% MTF)

Quantum efficiency was found to be 100 percent with a thick phosphor. The

thinner phosphor, the higher the resolution, but less quantum efficiency,

as predicted. The decay time of the phosphors was much shorter than the

TV frame period (~ 30 ms).

This system was used to obtain video tape images from dental teeth, indentation impressions on a NaCl crystal and a copper crystal in the microradiography mode. This system was also used to record real-time data from

various crystals in the x-ray diffraction topographic mode using synchrotron radiation.

[12] Boettinger, W. J. ; Burdette, H. E. ; Kuriyama, M. Rev. Sci. Instr.

50: 26; 1979.

[13] 1978 NDE Annual Report.

564-35
Figure 1 Synchrotron white beam transmission topograph of Czochralski

grown Ni crystal containing subgrains. Note the changing

shifted position of the oval shaped subgrain in various

Laue spots around the central spot.

564-36
Figure 2 Synchrotron white beam transmission topographs of an electron

beam melted and resolidified spot on a 111 surface of Si.

Notice the residual stress pattern which extends outward from

the weld spot.

564-37
Figure 3 Synchrotron white beam topographs of single A1 powder particles

solidified with large undercooling. The top left shows a particle which is a single crystal and which had only one

nucleus. The top right shows a particle having two grains

while the bottom left shows a deformed particle.

564-38
Figure 4 ACT topographs taken of a directionally solidified [(001)]

Mar M 200 monocrystal. The mosaic structure is evident in

the top left and full diffraction is obtained by rocking the

crystal 1° during exposure. The bottom picture is an enlargement showing a grain composed of a single dendrite.

564-39
Figure 5 Enlarged view of 040 white beam topograph of Fe-24 at. % A1

grain showing dumbbell image contrast of inclusions.

564-40
05 c 05

•i- 5-

03

C i— f

ra 05

s- x:

05 P p c O -rtO p

S- V) 05 C O VQ. ro • O S- P 05

X2

C 3 -O O to

•rU pu

05 P

05

S- P

05C

05

fO

05 05 U x: O • P

t- >>

s- o to 3 r- O

to I—

(0 I—

C_) I— <c <

to

05S-3

05

564-41

lomain

images.
FILM PLATE

SYNCHROTRON RADIATION TOPOGRAPHY OF SODIUM CHLORIDE

8 KeV Synchrotron Radiation Operated at 5.25 GeV 16 mA

Exposure Time: 5 minutes on Ilford 1-4 50pm Nuclear Emulsion Plate

Figure 7 An 044 topograph of an indented NaCl crystal taken at the

exact Bragg angle. The inset illustrates an x-ray optical

arrangement for changing the glancing angle 0^ n

-

564-42
SYNCHROTRON RADIATION TOPOGRAPHY OF COPPER CRYSTAL

IN THE BRAGG GEOMETRY

Figure 8 A series of topographs from a Cu crystal with Knoop indentations.

Each topograph was taken at a different glancing angle 0^ n and a different observation angle, 6

out

- This set of topographs opens

up a new avenue for quantitative characterization.

564-43
ENERGY

Figure 9 Near-edge absorption spectra for

(a) pure Fe

(b) chromate-passivated Fe film

(c) nitrite-passivated Fe film

(d) air formed film on Fe
R ( A)

Figure 10 Fourier transform of the spectrum shown in figure 9(b).

Solid line shows the magnitude and the dashed line shows

the imaginary part of the transform.

564-45
0 = 0

0 = 90 °

(a) Longitudinal Component

Figure 11 Longitudinal component radiation pattern for a dislocation source.

0 = 180 °

(b) Transverse Component

Figure 12 Transverse component radiation pattern for a dislocation source.

564-46
90

Figure 13 Longitudinal component radiation

pattern for a microcrack source.

564-47
Kernel

Figure 14 The beginning of the vertical response to a vertical force in

a half-space with horizontal planar surface. This time series

can be thought of as the kernel to be deconvolved out. This

particular kernel is very ill-conditioned rendering deconvolution particularly difficult.

564-48
1.50

1.20

0.90

0.60

0.30

Answer

0.00

-0.30

-0.60

-0.90

- 1.20

0.00 9.00 18.00 27.00 36.00 45.00

Dimensionless Time

Figure 15 A hypothetical source curve. The 'answer' to be found.

564-49
Answer

Kernel

With 8

Bit

Noise

Figure 16 A hypothetical resulting output signal obtained from the convolution of the first two curves with 8-bit noise (± 0.2%) added.

564-50
Dimensionless Time

Figure 17 The approximation to the solution using 'real time 1 deconvolution which is simply the routine inversion of the convolution

matrix as a lower diagonal matrix (compare with figure 5).

Note: This curve oscillates between ± 10 5

.

564-51
Deconvolution

Carried

Out

Using

FFT

Division

1.50

1.20

0.90

0.60

0.30

-0.00

-0.30

-0.60

-0.90

- 1.20

0.00 9.00 18.00 27.00 36.00 45.00

Dimensionless Time

Figure 18 The approximation to the solution using division of the FFT

of the output signal by the FFT of the kernel with 43-points

of zero padding added to remove an obvious time aliasing

error (compare with figure 5).

564-52
Dimensionless Time

Figure 19 The 'best' approximation (in the sense of minimum error in the

time domain) obtained from the SVD procedure (compare with

figure 5). While obviously orders of magnitude better than

the previous approximations, this approximation is in considerable error throughout the frequency domain.

564-53
Quotient

Obtained

Using

Boundary

Root

Filtering

Dimensionless Time

Figure 20 An approximation obtained using boundary-root filtering and

radiused FFT deconvolution methods. This solution while

appearing more 'jittery' than the preceding is actually more accurate in the frequency domain as well as giving a good

approximation in the time domain (compare with figure 5).

564-54
Figure 21 Debonding of MnS inclusion due to indentation of uncharged,

temper embrittled A533B.
(a) 1.9 x 105 Wm"1

(c) 3.3x105 Wm'1

(e) 5.7 x 10 5 Wm-1

(b) 2.7 x10s ms"1

(d) 4.1 xIO5 Wm'1

(f) 6.4 x10s Wm"1 0.5 mn

Figure 22 The effect of qa upon melt profile and solidifiecation microstructure of 2219 aluminum.

564-56
(b) 2.7 x 105 ms'1

(d) 4.1 xIO5 Wm'1

0.5 mm

Figure 23 The effect of qa upon melt profile and solidification mirostructure of 1100 aluminum.

564-57
6

qa/Wrrf1

Figure 24 (a) Acoustic emission energy emitted during solidification

(energy has same arbitrary units as figure 15a) and

(b) Melt depth verses qa for 2219 aluminum.

564-58
0.15 IE

E

Q.

CD Q

CD

qa/Wrrf1

Figure 25 (a) Acoustic emission energy emitted during solidification

(energy has same arbitrary units as figure 14a) and

(b) Melt depth verses qa for 1100 aluminum.

564-59

METALLURGICAL PROCESSING

Task 12143

Metals processing research plays a central role in the Division's activities. The properties of alloys depend on their compositions and microstructures, which are dictated by their processing history. Thus, the

effective performance of components in societal use depends strongly on solidification and solid state transformation processes, diffusion, and

other kinetic changes that alloys undergo during production and shape

forming operations. The central objective of this task is to develop

data, measurement techniques, theory, and predictive models relating

variables during metallurgical processing to microstructures, hence

properties and performance of alloys. In addition, the Diffusion in

Metals Data Center of the National Bureau of Standards is located in

this group. This Center is a national metallurgical resource that

provides a central source of extensive evaluated data on diffusion to

the technical community at large.

A major development during 1982 was the obtaining of special funding

from Congressional appropriations for new work on Metals Processing.

Three million dollars were provided to NBS, for one year only, to develop

new activities in rapid solidification and alloy coatings. These two

technological fields show great promise of providing new and improved

materials, which impart striking increases in strength, wear-resistance,

corrosion-resistance and electric transformer efficiency. This funding

has allowed establishment of advanced metals processing facilities that

will be used as part of a continuing program to provide measurements,

predictive models and standards needed for these technologies. Cooperation is being established with industry in which NBS will supply alloy

samples for research, measure critical data, and provide guidelines to

industrial designers who are developing new alloys. During the past

year, numerous guest workers, industrial scientists, and distinguished

visiting faculty members, such as Professor D. Turnbull of Harvard

University, have come to NBS to participate in this program, for periods

up to six months, and exchange information concerning these technologies.

Strong interactions have been developed with other Government agencies

in these areas. New projects on rapid solidification and alloy coatings

supported by the Defense Advanced Research Projects Agency and the Army

Research Office have been initiated. The Proceedings of a National

Workshop on Rapid Solidification held at NBS were published as an NBS

report in December 1981. The purpose of this workshop was to provide

coordination and guidance for the Government-wide program on rapid

solidification and to determine means of involving industry more fully

in this program. All Government agencies with significant programs in

this field participated by providing overviews of their needs and plans

for these materials. Major applications were discussed for rapidly

solidified aluminum alloys, superalloys, ferrous alloys, and specialty

materials, such as metallic glass. The workshop format then allowed

response from industrial and academic representatives. These responses were summarized in the report. One recommendation of the workshop was that there was need for the establishment of facilities at NBS to provide

workers in this field with rapidly solidified materials for research

purposes, since these materials are often not otherwise available.

564-61
As a result of our current program, the metals processing laboratory has

been significantly expanded and reorganized. Facilities now are available

for study of all three major types of rapid solidification: powder

production, ribbon production, and surface treatment. Work is being

done on micropowder production by atomization, metallic glass production

by melt spinning, and surface modification by electron beam melting and

refreezing. A recent major addition to these facilities is a system for

producing powders by electrohydrodynamic atomization techniques. Very

fine droplets are formed with aid of an electric field. Upon rapid

solidification of these droplets, submicron size powders are formed

whose characteristics and microstructure can be examined to determine

the effect of processing conditions on nucleation and solidification in

individual particles.

A gas atomization system also is being constructed to produce larger

sizes and quantities of rapidly solidified powders, which can then be

consolidated to form bulk specimens. Consolidation will be achieved,

for example, by a hot isostatic press that is being obtained. New alloy

coating facilities being developed include a plasma-arc-transfer alloy

coating system, a laser surface melting facility and improved alloy

diffusion measurement equipment. The aim of this work is to produce

quantitative measurements and understanding of rapid solidification and

alloy coatings in order to provide predictive modeling and thus allow

improved control of metal processes and products.

Rapid solidification studies are aimed at providing alloy designers with

guidelines for control of these processes. As an example, measurements

are being made of means of obtaining extended solid solubility. Experiments

have been performed on Ag-Cu alloys using electron beam surface melting

and melt spinning. At solidification velocities above 100 cm/s, considerable extended solubility has been obtained. These experiments use Ag-Cu

as one of a broad class of alloys with a retrograde solidus, where

enhanced solubility must be caused by a solute trapping mechanism.

Predictive modeling is being used to relate solubility measurements to

the To curve, which is the locus of compositions and temperatures where

the liquid and crystalline solid free energies have the same value.

Hence, To represents the highest interface temperature at which the

partition coefficient can be unity. Obtaining special alloy properties

characteristic of the single phase alloy thus depends on cooling the

alloy rapidly below To before two-phase separation can occur.

In diffusion studies related to alloy coatings, the newly recognized

phenomenon of diffusion-induced grain boundary migration is being investigated and measured. It is found that greatly enhanced mass transport

useful for producing new improved alloy coatings can be obtained by this

process. In particular, metals can be alloyed to surprisingly large

depths from the surface without subjecting the coated sample to high

temperatures. If high temperatures are avoided in the coating process,

improved surface properties can be obtained without degrading the properties of the underlying bulk material.

In other areas of metals processing, new signal-processing techniques

have been developed to improve signal-to-noise ratios during i_n situ

ultrasonic measurements of solidification interface positions and velocities.

564-62
This result is important for ultrasonic monitoring and control of continuous

casting of polycrystalline alloys, where reflections from grain boundaries

are important. Convection produced during directional solidification is

being measured and related to predictive models. Surface tension measurements in liquid alloys have been related to surface segregation effects

in these melts. In making such measurements, techniques were developed

which for the first time allow application of Auger methods to determine

liquid alloy surface segregation with direct comparison to surface

tension. As part of the continuing Diffusion in Metals Data Center

effort, a computerized bibliographic reference system has been put into

operation to allow improved retrieval of diffusion information.

Task members are currently active in organizing a national conference on Rapid Solidification Technology; Principles and Technologies to be held

at NBS in December 1982. During the past year, conference sessions were organized on diffusion processes and on materials processing in microgravity

at international conferences held by the American Society for Metals and

the Materials Research Society. Task members serve on advisory committees

for the National Science Foundation, Solar Energy Research Institute,

and the National Aeronautics and Space Administration; on boards of

international journals on diffusion and crystal growth; and on working

committees of the ASTM, AIME, American Society for Metals, and the

National Materials Advisory Board, including chairpersonship of the NMAB

committee on rapid solidification processing.

Metals Processing Laboratory

Subtask 1 of Task 12143

W. J. Boettinger, F. S. Biancaniello, S. D. Ridder, R. J. Schaefer, and

R. D. Shull

To accomplish the objective of the metals processing initiative in the

Metallurgy Division, this laboratory has continued to be expanded to

permit research into the processing-microstructure-properties relationship

utilizing innovative processing methods. A strong thrust in the area of

alloy powder formation and consolidation is underway as well as improvements

in electron beam surface melting and melt spinning techniques.

A new metal atomizing chamber has been designed and is currently under

construction. When complete, this device will be used to produce up to

50 kg of rapidly solidified alloy powder. The system has been designed

to allow for various atomizing techniques and to maintain an inert

environment throughout the atomizing and powder handling process. For

the initial atomizing trials the system will consist of a vacuum induction

tilt-pour furnace and inert gas impingement and atomization via an induction heated tundish. The bulk of the atomized powders will be

collected in a separately removable, vacuum tight can mounted below the

atomizing tower. The fine metal dust will be collected in a demountable

cyclone separator. This collection system will allow us to recover and

maintain a clean and inert atmosphere for all the powder produced down

to submicron sizes. A hot isostatic press unit has been ordered for the

consolidation of metal powders into near net shapes for property determinations.

564-63
Additionally, powders of various aluminum alloys have been produced by

an electro-hydrodynamic method which forms and ejects small quantities

of extremely fine (< 10 pm diameter) alloy powders. A major advantage

of this method is that many of these particles are electron transparent

and permit relatively easy characterization This process has been used

to study the solidification dynamics of metal alloys subjected to large

amounts of undercooling before freezing occurs. The systems studied so far include Al-Fe, Al-Mn, Al-Si, Al-Ge, Al-Cu, and Al-Cr.

The electron beam surface melting facility has been further upgraded by

the addition of a stepping motor, an oscilloscope, a deflection coil -beam

current synchronization system, and new devices for characterizing the

energy distribution in the beam. These additions have enabled us to more precisely characterize the melting parameters required to meet the

objectives of investigations on many different alloy systems. For

example, the equipment has been used to produce continuous amorphous

surface layers for acoustic studies, remelting and consolidation of

plasma-sprayed carbide layers on aluminum for improved abrasive wear

resistance, rapidly solidified surface layers on steel for wear and

microhardness study, and rapidly solidifed surfaces on alloys of aluminum,

silver-copper, and titanium for microstructural analysis.

A second, more sophisticated, vacuum melt spinning apparatus has been

constructed for the preparation of metallic alloy ribbons formed by

cooling the alloy from the liquid state at rates approaching 1 M°/s.

Such fast liquid quenching has been demonstrated to be responsible for

the creation of metallic glasses and metastable crystalline alloys.

Investigations of the morphology and structure of these quickly solidified

materials, with particular attention devoted to the effects of variations

in processing parameters, are presently being conducted.

Rapid Solidification

Subtask 2 of Task 12143

W. J. Boettinger, S. R. Coriell, R. J. Schaefer, and J. W. Cahn

This project is focused on increasing knowledge of the kinetic processes

which occur during the rapid solidification of alloys. A broad class of

experimental results on rapidly solidified materials are difficult to

understand because existing theory needs extension to higher solidification

velocities and because accurate quantitative experiments are difficult

to perform due to the high cooling rates and small specimen sizes. The

current work of this project investigates: (1) the solidification

conditions required to produce material free of microsegregation and

having solubilities for alloying elements in excess of the equilibrium

amounts; and (2) the effects of nonequilibrium interface kinetics on solidification theories. Summaries of progress in these areas are reported below.

(1) Microsegregation and Extended Solubility

Electron beam surface melting experiments have been performed on a series of Al-based alloys with the goal of determining the conditions of

absolute stability, and a series of Ag-Cu alloys with the purpose of

determining the conditions for extended solubility.

564-64
Al-Based Alloys

During the resolidification of an alloy following electron beam

surface melting, the sol id- liquid interface experiences a sequence

of conditions of growth velocity and temperature gradient, depending

upon the specific mode of melting. It has been found that in many

cases this sequence of conditions can completely bypass the range

of conditions where steady-state morphological stability analysis

predicts an instability leading to cellular solidification. At

some stages the planar interface is stabilized by high temperature

gradients while at other stages the gradients in the liquid may be

very small but the interface moves sufficiently rapidly to experience

absolute stability due to surface energy. The latter regime is of

particular significance, because it represents a drastic departure

from the behavior expected by a mere extrapolation from lower

velocity behavior.

An analysis of the influence of various metallic solutes on the

solidification of aluminum has shown that the phenomenon of absolute

stability is expected to occur at relatively low solidification

velocities, or high solute concentrations, in samples containing

manganese as the only solute. However, it is also clear that only

small concentrations of certain impurities with small solute partition coefficients are required to upset this absolute stability and

produce a cellular solid-liquid interface. It was found that

aluminum-manganese without detectable cellular structure could be

produced by the rapid solidification following electron beam surface

melting of chi 11 -cast samples in which a conventional cellular

structure was present, but that the concentrations at which this

could be attained were lower than predicted. Current efforts are directed toward techniques of surface preparation prior to electron

beam melting to reduce the possibility of local contamination.

M-Cu Alloys

The extension of solid solubility by rapid solidification is common,

yet the relationship between alloy composition, growth rate, and

thermodynamic constraints has not been significantly investigated.

The system Ag-Cu has a particularly simple thermodynamic basis and

a full metastable phase diagram including T

q curves has been calculated by Joanne Murray as part of the Metallurgy Division phase

diagram activity. Of particular interest is the appearance of a retrograde solidus for both Ag and Cu solid solutions indicating

that extension of solubility beyond the respective retrogrades must

be accomplished by solute trapping.

A series of experiments has been performed with compositions between

pure silver and the eutectic composition using electron beam surface

melting of ~ 1 mm wide weld strips at velocities between 1 cm/s and

200 cm/s. In these experiments the growth velocity is simply

related to the e-beam traverse rate by a geometrical factor related

to the weld puddle shape, which can be determined from metallography.

Considerable effort has been expended on developing a method for

preparing samples for electron microscopy from the surface melted

564-65
alloys. Alloy compositions which are dendritic or eutectic at

growth rates of 1 cm/s become single phase, segregation free at

growth rates (depending on composition) of ^ 100 cm/s. For alloy

compositions beyond the equilibrium solubility limit, this structure

indicates solubility extension. For these alloys an interesting

structure of bands of high and low copper content develops normal

to the growth direction at intermediate velocities. The measurement

of velocities required to produce extended solubility should for

the first time, permit the evaluation of various theories for

extended solubility by rapid solidification.

(2) Interface Kinetics

Significant departures from local equilibrium at the crystal -melt interface can exist for solidification at rapid rates. Perhaps, the highest

measured crystal growth velocities (50 m/s) are those of Ni dendrites

growing into pure undercooled melts as reported by Walker and Colligan

and Bayles. Recent theoretical (Langer and Mul 1 er-Krumbhaar) and experimental (Glicksman et al.) advances in our understanding of dendritic

growth allow accurate calculation of the heat transport limited rate of

dendritic growth as a function of melt undercooling. Inclusion of

interface kinetics into the heat transport model of dendritic growth has

been performed in collaboration with Professor David Turnbull to extend

the model to high solidification velocities. We have used previous

results on the effect of interface kinetics on the morphological stability

of a solidifying sphere to calculate the effect of interface kinetics on the dendritic tip radius and hence the growth rates. An interface

kinetic coefficient based on the estimated velocity of sound in molten

nickel, provides a good fit to the dendritic growth data at high velocities

as a function of melt undercooling.

Recent advances in the technology of rapid solidification, e.g., laser

or electron beam melting and refreezing of thin layers on substrates, as well as the observed absence of microsegregation in many rapidly solidified

materials has focused increased attention on the phenomenon of morphological

stability at rapid solidification rates. The theory is used to determine

the conditions under which a planar sol id- liquid interface is stable to

small perturbations and hence when microsegregation dpes not occur. Of

particular interest is the fact that the theory predicts absolute stability —i.e., stability for any solute concentration and any positive temperature

gradient--provided that the velocity exceeds some critical (high) value.

In collaboration with Professor R. F. Sekerka, linear perturbation

theory was used to study morphological instability for rapid directional

solidification at constant velocity under conditions where there is

significant departure from local equilibrium at an initially planar

sol id- liquid interface. One of the more dramatic manifestations of the

departure from equilibrium at rapid rates is the nonequilibrium partitioning

of solute as may be characterized by a nonequilibrium value of the

distribution coefficient k, which is the ratio of solute concentration

in the solid to that in the immediately adjacent liquid from which it

freezes. For example, measured values of k for silicon have differed by

orders of magnitude from the equilibrium value for solidification rates

of the order of a few meters/second and such differences would be expected

to have a dramatic effect on morphological stability.

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One way of attempting to account for the effect of a nonequilibrium

value of k on morphological stability would be simply to substitute the

value of k measured at the velocity for the unperturbed state into the

classical analysis. In fact, the critical value of the velocity for

absolute stability is proportional to k

2 /(l-k) so a big effect might be

expected. However, such a procedure of substitution of the actual value

of k is not strictly correct.

Under conditions where the segregation coefficient k depends significantly

on velocity v, the stability criterion depends explicitly on both k and

8k/8v and instabilities that are oscillatory in time can occur for

solute concentrations that are much smaller than those that would be

necessary to cause nonosci 1 latory instability for the same k if 3k/8v

were simply neglected. Such oscillatory instabilities seem to be related

to a "solute pump" mechanism according to which local changes in k, due

to periodic changes in local interface velocity v, can occur out of

phase with local interface position, thus resulting in lateral inhomogeneity

of concentration on a length scale large enough that the resulting

instabilities will not be suppressed by capillarity. Such instabilities

can, however, be suppressed by a sufficiently large dependence of interface

undercooling on v. When present, oscillatory instabilities lead to a three-dimensional segregation pattern in which periodic solute variations

in the two transverse directions are modulated by a periodic variation

in the direction of growth.

Diffusion-Induced Grain Boundary Migration

Subtask 3 of Task 12143

J. R. Manning, D. B. Butrymowicz, and J. W. Cahn

In metallic systems, there is clear experimental evidence that grain

boundaries can be induced to migrate under certain conditions when

substitutional solute atoms are diffused along the boundaries. The

formation of alloyed zones by diffusion-induced grain boudary migration

has been observed at relatively low diffusion temperatures under conditions

where lattice diffusion is essentially frozen out but where appreciable

diffusion transport along grain boundaries occurred. This effect has

been measured quantitatively in Cu-Zn and Cu-As in recent work on this

project. Copper specimens were exposed to Zn or As vapor from a-phase

alloys. Diffusion into the grain boundaries caused migration of these

boundaries and deposition of alloying elements in the regions traversed.

Large surface alloyed regions were formed, which effectively provided

alloy coatings in the regions through which where the grain boundaries

had migrated. The objective of this work is to establish the mechanisms

and critical parameters controlling this phenomenon and thus provide

predictive models for this process.

Electron microprobe composition profiles and area composition scans of

these specimens show sharp step-like discontinuities in alloy composition

at the edges of the alloyed regions. Each alloyed region is bounded on one side by the final position of the grain boundary and on the other

side by the initial position of the grain boundary. This effect has

been observed both in a hydrogen atmosphere which excludes oxygen from

the sample and under conditions where on appreciable amount of oxygen

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enters the region being alloyed. Close control of the vapor and of

alloying conditions does not seem necessary to produce this phenomenon.

Hillocks were observed to form on Cu-As samples, indicating that stresses

are being generated, probably as a result of Kirkendall fluxes along the

grain boundaries.

Theoretical models are being developed to explain the effects being

observed. Current attention is focused on models that produces grain

boundary migration as a result of climb of grain boundary dislocations.

It is presumed that the alloying elements, Zn and As, diffuse along the

copper grain boundaries faster than copper does itself. Thus, at temperatures where grain boundary diffusion can occur, there is a net flux of

atoms into the boundaries. Grain boundary dislocation climb can absorb

these additional atoms, but such climb will cause the boundaries to

migrate normal to themselves. The migrating boundaries then should

leave behind alloyed regions in the areas traversed, as is observed.

If a sharp concentration gradient is maintained at the leading edge of

the boundary, the diffusion potential down the boundary can be maintained,

thus providing steady state migration. The experimental observation

that the solute composition of the alloyed regions in CuZn and CuAs does

not decrease as migration proceeds, and may even increase somewhat, is

consistent with this theory. This theory also may explain why diffusioninduced grain boundary migration has not been observed in ceramics. To

preserve charge neutrality in ionic ceramic materials, Kirkendall fluxes

of both anions and cations would be required to allow migration. Conditions for di f fusion- induced grain boundary migration thus would be more difficult to obtain in ceramics than in metals, where a diffusion potential for only one species is required.

Diffusion-induced grain boundary migration is important not only for

alloying but also for leaching, since much the same phenomena are observed

to occur for de-alloying (unmixing) as for alloying (mixing). Either

mixing or unmixing can occur, depending on the sign of the diffusion

potential maintained in the particular experiment. These processes

influence cellular precipitation and also have been observed in other

solid-solid phase transformations involving diffusion couples. Applications have been made to fabrication of thin film electronic devices and

control of degradation in metal contacts.

Diffusion in Metals Data

Subtask 4 of Task 12143

D. B. Butrymowicz, J. R. Manning, and R. M. Hayes

Knowledge about the motion of atoms in alloys is important for studies

of phase transformations, surface alloying to form coatings, oxidation

rates, and many other phenomena dependent on mass transport in the solid

state. An understanding of the parameters that control the rates at

which these processes occur provides part of the basis for innovative

development of new materials and control of their behavior. The NBS

Diffusion in Metals Data Center provides a unique central source where

data from the world's technical literature on diffusion and related

kinetic processes are collected, evaluated, and then made available to

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the industrial and academic communities. More than 25,000 documents

reporting diffusion data now comprise the Center's database.

Automation of the bibliographic and classification files is being carried

out to make the information contained in these reference files more easily searchable for locating specific data and more publicly accessible

to the technical community. The documents on file have been classified

and indexed according to the alloy systems and diffusion processes on which they contain data. This information along with bibliographic

information is being processed into computer-readable form. A database

management system has been designed and tested to allow entry of this

information in an on-line computer available for automated searching by

alloy compositions. Ability to obtain special types of diffusion information listed according to keywords also will be provided by this computerized

system. This type of information base is important for evaluation of mass transport data. Studies of diffusion in grain boundaries and in

iron-nickel -chromium alloys are currently being undertaken. This work

forms part of a larger effort to develop a more complete data base for

metals processing applied to critical materials.

Evaluation activities relating to technologically important copper

alloys have resulted in a handbook of critically evaluated data prepared

for the International Copper Research Association (INCRA). A camera-ready

copy of this 500 page volume was delivered to the industrial research

association as part of a cooperative agreement funded by the copper

industry. This work will be published as part of the INCRA Metallurgy

of Copper Series.

Ultrasonic Measurement of Solid/Liquid Interface Position during Solidifi - cation and Melting of Metals

Subtask 5 of Task 12143

R. L. Parker

Ultrasonic techniques are being developed to provide real-time, i_n situ , nondestructive measurement of the position, velocity, and shape of

solidification interfaces in opaque materials. The use of pulse-echo

ultrasonic flaw detectors to detect the presence and location of cracks,

voids, and other flaws in metals and nonmetals is well known. The

sol id- liquid interface in a melting or freezing metal can also be considered

as a defect, in that there is a measurable difference in both sound

velocity and density across the interface. For normal incidence of

longitudinal waves in a typical case, about 10 percent of the pressure

amplitude of the incident wave would be expected to be reflected. Thus,

such a technique could be considered as a method for measurement, feedback,

and closed-loop process control in such applications as continuous

casting of metals.

A paper on this subject was presented at the First Conference on the

Applications of Physics in the Steel Industry, October 5-7, 1981 at

Lehigh University, Bethlehem, PA, which was jointly sponsored by the

American Iron and Steel Institute and the American Physical Society.

The proceedings of this Conference have been published by the American

Institue of Physics, May 1982. In this paper are summarized our ultrasonic

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pulse-echo measurements on the unidirectional solidification of tin in a Bridgman furnace; our ultrasonic pulse-echo measurements on large-grain

304 stainless steel at room temperature, demonstrating signal enhancement

by computer spatial averaging in the presence of strong Rayleigh grain

scattering; and a survey of earlier published work.

Current NBS work is focused on the study of the measurement factors

inherent in possible use of the method for process control, as well as possible use for interface characterization; the latter use may be

termed "ultrasonic metallography." The former use, process control, is

important in the steel industry. For example, in continuous casting of

steel, it would be useful to know at all times whether the solid skin

thickness is sufficient to withstand the hydrostatic head of perhaps

10 meters or more of liquid steel, in order to forestall breakouts. Such

breakouts can occur several times per year in such a caster, and they

can be quite costly in repairs and reduced productivity. In order to

make ultrasonic measurement of the skin thickness in a steel continuous

caster, one must be able to do four things: couple an ultrasonic signal

to the steel surface, propagate it to the solid-liquid interface (mushy

zone in the case of alloys), obtain an echo from that interface, and

identify the echo return in the presence of substantial noise from

Rayleigh (grain) scattering. In the paper referred to above, the signal

identification by computer enhancement was determined; and current work

by others on EMATS transducers using noncontact Lorentz- force generation

of ultrasonic pulses in hot steel billets appears to have solved the

first (coupling) problem.

To examine the ultrasonic propagation through very hot steel and reflecting

from the sol id- liquid interface, an RF- induction furnace, capable of

melting steel in an unidirectional (Bridgman) geometry, in an argon

atmosphere, while coupled to a conventional transducer, has been designed,

constructed and put into operation.

Using 1 MHz and 2.25 MHz longitudinal waves, we have made preliminary

determinations of the sol id- liquid interface location in 304 stainless

steel rods, in the presence of substantial grain growth and its resulting

attenuation, as well as absorption from other mechanisms (also some tests on carbon steel). One may consider the propagation and reflection

measurements as analagous to measurement of the (frequency-dependent)

transmission (T) of an electrical filter: Tp(u))*T

r (w). In the case of

grain growth and interface motion, these two functions are time-dependent,

too. Their measurement is essential for proper application of this

measurement technique to industrial use.

Surface Tensions and Their Variations with Temperature and Impurities

Subtask 6 of Task 12143

S. C. Hardy

Components of a bulk liquid phase which have low intrinsic surface

tensions will preferentially segregate at free surfaces. Although the

thermodynamics of this surface adsorption phenomenon was developed by

Gibbs over a hundred years ago, many questions remain unanswered about

details of the process such as the distribution of the adsorbed species

564-70
in the surface region and the interactions between coadsorbing species.

Adsorption can produce large surface tension reductions and, in some situations, surface tension gradients which generate fluid flows. The

resulting mass and heat transport are important factors in a number of

procedures involving materials processing.

Although the study of adsorption at liquid surfaces is an active field

of research, there have been almost no applications of modern surface

analysis techniques to liquids. We have started a program of such

studies of the surfaces of low vapor pressure metal alloys using Auger

electron spectroscopy combined with classical sessile drop surface

tension measurements. Our initial work has been with the Ga-Sn system.

The Sn was found to be strongly adsorbed at the surface. Calculations

of surface concentrations from the Auger measurements require knowledge

of inelastic mean free paths and back scattering factors for the Auger

electrons. Using recent theoretical calculations of these quantities

for Ga and Sn, the surface composition of the alloys was determined from

the measured Auger electron line amplitudes. The surface concentrations

of Ga and Sn were found to be substantially in agreement with surface

concentrations deduced from thermodydnamic data assuming all the adsorption is in the top layer. This result supports the monolayer model of

surface adsorption for the Ga-Sn system.

Convection During Directional Solidification

Subtask 7 of Task 12143

R. J. Schaefer and S. R. Coriel 1

This research is directed toward an understanding of the fluid flow and

solute segregation which occur during solidification. The nature of the

fluid flow, its effect on the shape of the crystal-melt interface and

the resulting distribution of solutes is examined. In particular, the

role of solutal convection (gravity driven flow due to solute gradients)

during the vertical directional solidification of a binary alloy is

being studied both theoretically and experimentally. Solutal convection

affects the microstructure and chemical homogeneity of directionally

solidified alloys, and hence essential properties and performance such

as fracture and corrosion.

Previous theoretical work [1] on solutal convection has shown that

convective instabilities can occur at very low solute concentrations,

e.g., 10 ppm for the solidification of lead alloys containing tin.

Previous experimental work [2], on the growth of lead-tin off-eutectic

alloys has established that solutal convection can cause extensive

macrosegregation and prevent the growth of aligned composites. Our

present effort is to develop a detailed understanding of the fluid flow

which occurs during directional solidification, and to develop predictive

models for macrosegregation and solute redistribution.

Experimental study of convection during directional solidification has

used succi nonitrile with and without small additions of ethanol. In

this system the solid-liquid interface can be viewed directly and convection can be measured by tracking the motion of small particles suspended

in the liquid. It is found that even in high purity material a convective

564-71
flow field is present due to radial temperature gradients induced by

heat losses and by the influence of the container walls. These radial

gradients result in a non-planar interface: when solute is present the

resulting convective flow leads to the development of a macroscopic

depression in the central region of the sol id- liquid interface, which

subsequently becomes the site of interface breakdown into a conventional

cellular structure. By adding auxiliary heating in the region surrounding

the interface, the thermal convection can be suppressed and the formation

of the macroscopic depression and subsequent cellular structure is

avoided. Thus, convective effects of a purely thermal origin dominate

in this system unless special precautions are taken, but true solutal

convection effects may be observable when the thermal convection is

suppressed by properly designed auxiliary heaters. The overall decomposition of the solid-liquid interface into a cellular structure takes place

at approximately the solidification velocity and solute concentration

predicted by the stability theory. Details of the experimental observations

and theoretical calculations for succinonitrile-ethanol mixtures have

been reported [3].

In collaboration with R. G. Rehm and G. B. McFadden of the Mathematical

Analysis Division, a theoretical model of double diffusive-convection

during directional solidification of a binary alloy is being developed

for low Prandtl number melts (metals and semiconductors). The nonlinear

partial differential equations of fluid flow together with equations for

temperature and concentration are solved numerically. The spatial

variation of the solute concentration in the solidified alloy is evaluated

from the numerical results.

In collaboration with R. F. Boisvert of the Scientific Computing Division

and M. E. Glicksman and colleagues at Rensselaer Polytechnic Institute,

the stability of the flow between two vertical, infinite, rigid, coaxial

cylinders held at different temperatures, has been analyzed by linear

stability theory. For a Prandtl number of 22.8 and a radius ratio of

0.02, the flow is unstable to an axi symmetric perturbation at a critical

Grashof number of 2150; the wave speed of the instability is comparable

to the maximum velocity of the unperturbed flow. When the rigid outer

cylinder-fluid interface is replaced by a crystal -melt interface which

can change shape, two new modes of instability occur at lower Grashof

numbers. There is an asymmetric instability with a critical Grashof

number of 180 and an axi symmetric instability with a critical Grashof

number of 460; for both of these modes the wave speed of the instability

is several orders of magnitude smaller than the unperturbed flow velocity.

These calculations were motivated by and are in general agreement with

recent experiments at Rensselaer Polytechnic Institute on succinonitrile.

A long vertical cylindrical sample of succinonitrile was heated by an electrical current through a coaxial vertical wire so that a vertical

melt annulus formed between the coaxial heater and the surrounding

crystal-melt interface. Above a critical Grashof number of circa 200, a helical crystal -melt interface formed which rotated steadily about the

cylinder axis; the wave speed was several orders of magnitude less than

the base flow velocity. These experiments demonstrate a crystal-melt

interface instability under conditions for which in the absence flow,

the crystal-melt interface would be morphologically stable.

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[1] Cori ell, S. R. ; Cordes, M. R. ; Boettinger, W. J. ; Sekerka, R. F. J. Crystal Growth 49: 13; 1980.

[2] Boettinger, W. J. ; Biancaniel lo, F. S. ; Coriell, S. R. Met. Trans.

12A: 321; 1981.

[3] Schaefer, R. J. ; Coriell, S. R. Materials processing in the reduced

gravity environment of space, Guy E. Rindone, ed. , Elsevier, 1982,

p. 479.

564-73

MECHANICAL PROPERTIES AND WEAR

Task 12144

This task addresses measurements and standards needs concerned with the

application of metals to wearing situations, and also to their use as synthetic implants in humans. Specific projects are described below and

are concerned with various modes of wear, the mechanisms involved, the

effect of metallurgical parameters, the need for improved measurement

capabilities, and the provision of standards and reference materials.

The importance of wear to U.S. industry and technology has only been

appreciated fully in recent years. Studies indicating the costs of wear

have been conducted in three countries (U.S. costs are estimated at $30 B

to $50 B per year) and those results have led to increased Government and

private emphasis of wear control and wear research. Most of the work on wear in this task resulted from an expanded NBS program in FY80 through the

new Durability initiative. NBS has a unique opportunity in this field to

provide help to the industry in standards and measurements areas, as well as to contribute to an improved basic understanding of wear. One

area of current industrial interest involves coatings applied to metals

for improved wear (and corrosion) performance. More widespread use of

coating technology can conserve critical materials (by reducing their

use in bulk alloys) and can improve productivity by efficient use and

reuse of existing designs and components. However, the state of understanding of wear of thin metal coatings is not well advanced. Methods

for accurate wear testing of very thin coatings are not adequate. These

and other related needs are important technological questions for NBS to

address in the wear area; in fact, a new budget initiative this year on Metals Processing includes work on the wear performance of metals coatings.

Highlights of this year's activities include the provision through the

Office of Standard Reference Materials (OSRM) of a reference material

for conducting abrasive wear tests, the development of an ASTM standard

method for solid particle erosion testing, results on the galling wear

of a number of alloys, and studies of the break-in process in copper

alloys and aluminum alloys. One staff member is now Chairperson of ASTM

Committee G2 on Erosion and Wear, and Vice-Chairperson for the 1983 International Wear Conference to be held in Washington next April. Two guest

workers participated in our activities this year from the University of

Virginia, developing a new theory of wear emphasizing materials effects.

Two invited talks were given at the Gordon Research Conference on Wear

this summer by staff members. A one day symposium on microhardness-related

research was organized by a staff member and held at NBS during May; it

involved nine technical papers in this subject area.

The work on metallic surgical implant materials in this task covers a number of different studies including corrosion, fatigue, metal ion/protein

reactions, surface modifications, interfaces, and standards. Biomaterials

research has been a rapidly growing scientific effort throughout the

world over the past 15 years; as a result, hundreds of thousands of

people have benefited. This trend continues as improvements which are possible through advancing materials technology are made. The purpose

of this NBS work is to provide measurement methods, material property

564-75
data, and standards which are necessary for improved design, materials,

and quality control of metal implants. There is considerable interest

in the work done at NBS in this area; this is evidenced by many scientific

interactions, information requests, and invited talks to industry,

universities, and other groups. Staff members actively participate on the ASTM Committee F4 on Medical and Surgical Materials and Devices.

This past year saw the establishment of recommended tests for wear and

for corrosion. Both of these can be used for material tests in much

needed device performance standards. We are the coorganizer of the

Second ASTM Symposium on the Corrosion and Degradation of Implant Materials

to be held in Louisville, KY, May 1983. NBS will also handle arrangements

for the Second World Congress on Biomaterials which is to be held in

Washington, DC, in April 1984.

The task is divided into four subtasks whose activities and accomplishments

over the past year are described next. These subtasks are Metallic

Wear, Lubricated Wear, Wear Standardization and NDE, and Metallic Biological

Implant Materials.

Metallic Wear

Subtask 1 of Task 12144

K. J. Bhansali, P. J. Blau, L. K. Ives, F. Matanzo, S. Nutt, C. Olson,

and A. W. Ruff

This subtask consists of several projects concerned with the wear and

friction of metals. Studies are carried out of metal-to-metal wear

under clean conditions, and of metal wear under abrasive conditions.

The emphasis is on precise, meaningful measurements of wear and friction,

and on an improved understanding of wear mechanisms and the role of

metallurgical parameters. Wear studies are carried out in the laboratory

under carefully controlled conditions, in order to draw valid conclusions

about the mechanisms involved.

Composites of aluminum alloys with particles of chromium carbide have

been made by surface alloying methods. It was hoped that a better

interfacial bond between the hard carbides and soft aluminum matrix

could be achieved over the usual solidification approach for composites

involving silicon carbides. The different affinity for carbon is believed

to be greater between chromium and aluminum than between silicon and

aluminum. Hence, formation of a weak aluminum carbide phase at the

interface between silicon carbide and aluminum is more likely than at

the interface between chromium carbide and aluminum. Abrasive wear

tests were conducted on these composites. Results of the tests look

very promising as shown in figure 1. SEM examination of the wear scar region indicates a good bond between the chromium carbide particles and

the matrix. This work is being prepared for publication.

Investigations of the influence of metallurgical parameters on the

threshold galling stress also have been conducted, using the galling wear tester built last year. A series of Fe-Mn-Si alloys with controlled

variations in stacking fault energy (SFE) were obtained (supplied by ARMCO)

to explore the relation to galling threshold stress. The influence of

additions of alloying elements like Pb and Sn on the galling of brasses

was evaluated. The ratio (R) of threshold galling stress to penetration

564-76
hardness was used to evaluate relative galling tendencies of alloys. For

pure copper R is 0.007 whereas for 70 to 30 brass it is 0.048. This

increase in relative resistance to galling is believed to be due to

lower stacking fault energy of 70 to 30 brass compared to that of copper.

No galling has been observed so far in lead or tin bearing brasses up to

R values of 0.2. Such an excellent resistance to galling of lead or tin

bearing brasses is believed to be due to their poor shear strength owing

to the presence of a lead- or tin-rich phase at the grain boundaries.

Temperature is also believed to have a considerable influence on cross

slip of dislocations and hence on galling behavior. A modified sample

holder was designed and built to study galling behavior above room temperatures, up to about 700 °C, in the coming year.

In another project a wet sand abrasive wear test machine was modified to

also include normal force and frictional force measuring capabilities.

A project to study the effect of heat treatment of a 1090 steel on its

abrasion resistance using this wet sand abrasion tester, and also the

dry sand abrasion tester, has been initiated. A change in relative wear

ranking due to corrosion affects under wet conditions is expected.

A new project to investigate the effect of residual stress on abrasive

wear has been initiated jointly with the University of Notre Dame. A

system to measure the residual stresses using a blind hole drilling

technique was purchased and loaned to the University of Notre Dame.

Preliminary measurements there indicate that a definite residual stress

pattern is generated during dry sand abrasion testing. It is believed

that prior residual stresses may be removed during the initial wear-in

period and a steady state residual stress pattern is then established.

This will be studied further in the next phase. In addition, the effect

of pre-stress on the abrasive wear of carbide-containing alloys will be

i nvestigated.

In another project, investigations have continued on the influence of

microstructure and different wear modes on the friction and wear running-in

behavior of Cu-Al based alloys. In addition to the binary single phase

alloys studied in the previous year, two commercial alloys (CDA 638 and

688 bronze) and a polyphase Cu-12 wt. % A1 alloy were tested for unlubricated running-in behavior on the computer controlled block-on-ring (52100

steel rings) tribometer. In the commercial alloys, compositional difference

effects on friction coefficient changes during running-in were quite

pronounced. Part of these observed differences may relate to the different

balance of competing wear modes identified in post- test microstructural

studies of CDA 638 and 688 surfaces. Heat treatment effects on wear of

the Cu-12 wt. % A1 alloy were also investigated. The martensitic condition of this alloy gave not only lower hardness, but also lower wear loss

compared with the more equilibrium, two phase eutectoid microstructure

produced by a different heat treatment. Further effects of heat treatment

on both wear and friction of the Cu-12 wt. % A1 alloy are to be investigated in the next year.

Work is nearing completion on construction of a controlled atmosphere

tribometer with high vacuum capabilities. Within the next four months,

computer interfacing of the device should be completed. Studies of

surface contamination effects and controlled atmospheres on long-term

564-77
transitions in wear mode and on running-in behavior are planned, to

isolate the influence of combinatory factors responsible for net friction

and wear values. Changes in the contact conditions during the tests

(particularly the gas atmosphere composition) are also planned for

systematic study.

s Another project concerns the wear of HSLA steels having high ductility,

the so-called dual-phase steels. Five alloys have been studied along

with tool steel and low carbon steel under dry sliding conditions against

52100 bearing steel. The extended ductility property of the DP steels

does produce an increased wear resistance under these test conditions.

In contrast the yield strength itself does not determine (or correlate

with) the wear resistances. Two primary factors appear to determine the

wear; environmental conditions (water vapor content) and alloy plasticity

properties. Two basic types of wear debris particles are formed; small

primarily iron oxide particles, and larger primarily metallic particles.

These results are presently being prepared for publication. The experimental

work was carried out with the assistance of Ximing Meng, a Guest Worker

from China.

A new project this year is being carried out by a NRC-NAS-NAE postdoctoral

fellow. It concerns microscopic studies of sliding wear on titanium.

It is well recognized that titanium exhibits poor tribological properties,

however, the basic reasons are not understood. Presumably, they involve

the mechanical, thermal, and surface properties of the metal. This

study is exploring the significance of slip system constraints, mechanical

twinning vs slip deformation, and surface conditions on the wear and

friction properties of titanium. Transmission electron microscope

results from worn specimens will be described in a talk planned for the

Electron Microscope Society Meeting this summer.

Work is continuing on the dry sliding wear studies of Ni alloy coatings

on steel. Results from the previous study have appeared in the ASTM

publication on Wear Testing of Coatings (see fig. 2). There it was shown that an amorphous alloy coating had good wear properties, and that

the laminar morphology (composition banding) and precipitate strengthening

effects in the heat treated alloy coatings were very significant features.

The new work, jointly conducted with Dr. Lashmore of the Materials

Chemistry Division, involves Ni alloy coatings containing small aluminum

oxide particles. Presumably, this approach may increase resistance to

abrasive-type wear and retain the good metal -to-metal wear characteristics.

Another project has been completed concernig the abrasive wear properties

of laser surface-melted aluminum and titanium alloys containing particle

additions of WC and TiC. Reductions in wear rates by a factor of 10 or more were found to result from this processing treatment. Studies of

the effect of microstructure, particle type and size, and composition

have been completed. A paper is being prepared for presentation at the

Fourth International Conference on Wear of Materials, scheduled for

April 1983 in Washington. This work has been done jointly with a scientist

at the Naval Research Laboratory.

In a project concerned with basic wear processes, a microscratch

hardness investigation of eroded copper specimens is being carried out

564-78
in a joint effort with Professor J. Moteff of the University of Cinncinnati.

The eroded copper specimens had previously been the subject of an extensive

electron microscopy investigation in our laboratory to determine the

relationship between microstructure and erosion conditions. Under mild

wear or erosion conditions, the conventional microhardness test is not

likely to be applicable as a means to study the resulting wear damage.

A microscratch hardness method is being examined in this new work to

determine if information can be obtained on the mechanical properties of

surface layers which may be no more than a fraction of a micrometer

thick.

In another project, transmission electron microscopy is being applied to

reveal the microstructure of worn surfaces and wear debris. The recently

acquired analytical electron microscope equipped with an x-ray energy

dispersive spectrometer and an electron energy loss spectrometer has

added a new dimension to this project. With this instrument, it has

become possible to probe changes in elemental composition and crystal

structure on a scale of a few nanometers. To take advantage of this

capability it has become necessary to develop suitable specimen preparation

methods. To this end, new procedures for preparing cross sections

through worn surfaces and for removing thin surface layers have been

developed. One area of particular interest in which electron microscopy

has been applied concerns the study of microstructural changes brought

about by plastic deformation during different kinds of wear. Fairly

extensive wear and characterization studies on copper have been carried

out in the past. The development of a dislocation cell structure and

the formation of crystallographic texture were revealed in that work.

Additional work on copper is planned to compare wear debris structure

with subsurface structure. The microstructural studies are also being

extended to other materials. The effect of stacking fault energy,

crystal structure, and precipitation hardening are being investigated.

Two commercial bearing steels, 52100 and carborized 4320, are being

examined. Further, a new area of investigation concerns the nature of

the microstructural changes that occur at the onset of scuffing. Scuffing

is a severe form of wear in lubricated systems that is usually associated

with failure of the lubricant film. Metallurgical factors, however,

play a significant role in determining the conditions under which scuffing

occurs.

Lubricated Wear

Subtask 2 of Task 12144

L. K. Ives, M. Peterson, J. Harris, and A. W. Ruff

An investigation of the lubrication and wear mechanisms of the solid

compound SbSb4 has continued. This project is sponsored by the Office

of Naval Research as part of a Navy program to develop lubricants with

improved anti wear capabilities, better high temperature stablility,

longer life to reduce maintenance costs, and the ability to lubricate

such difficult materials as titanium alloys and stainless steels.

SbSbS4 is the most promising of several compounds that were developed

with Navy support by an industrial research laboratory. The compound

was reported to impart a greatly improved load carrying capacity and

564-79
antiwear response in four-ball tests when blended into several conventional

base greases. The mechanism by which SbSbS 4 might show such improvements

was not determined although it was suggested that being a solid material

it might act as a solid lubricant, and indeed, comparisons were made

with MoS 2

. In order to study the solid lubricant characteristics of

SbSbS4 a series of tests with steel specimen materials were carried out

at temperatures ranging from 20 to 600 °C. At 20 °C a friction coefficient

of 0.7 to 0.8 was obtained. As the temperature was increased, the

coefficient of friction decreased to a value of about 0.4 at 250 °C and

approached 0.2 at 500 °C. These changes in friction coefficient are associated with thermal decomposition and oxidation of SbSbS 4 to form

other compounds, chemical reaction with the steel surface, and the

effect of temperature on the mechanical properties of the compounds

present. The initial reaction as the temperature was raised above 20 °C

has been determined to involve the release of sulfur and the formation

of Sb2 S 3. There was no evidence in these studies that SbSbS4 or any of

its compounds were effective solid lubricants in air at room temperature.

The reduction in coefficient of friction does, however, indicate that

compounds derived from SbSbS 4 do exhibit some lubricant properties at

elevated temperatures. Although it had been demonstrated that SbSbS 4 is an effective lubricant additive at high contact loads and speeds, its

performance might differ under less severe conditions, especially at low

sliding speeds where thermal effects might be minimized. To study this

regime a series of block-on-ring wear tests was conducted at a sliding

speed of 5.5 cm/s and load of 267 N. The block and ring materials were

52100 steel. A comparison was made between lithium base grease and the

base grease with additions of SbSbS 4 and S. The results are shown in

figure 3. Both S and SbSbS4 produced a significant but comparable

reduction in wear. Electron microscopy studies on surface films removed

from worn surfaces indicated that the formation of iron sulfides played

a significant role in the reduction of wear. The film formed when S was used as an additive differed from that for SbSbS 4

. With S the film was

found to consist primarily of FeS2 while both Fe^_

x

S and a layer of

amorphous SbSbS 4 were obtained when SbSbS 4 was used as an additive. The

significance of this finding is still being investigated.

Although experimental activities associated with the NBS Recycled Oil

Program were concluded at the end of last year, there was a continuation

of some activity into this year. In particular, an invited talk on the

subject of wear tests for the evaluation of rerefined motor oils was presented at the Chicago Chapter of the American Society of Lubrication

Engineers. Further, an invited paper summarizing results in our project

to develop a wear test to evaluate motor oils will be presented at the

Conference on Measurements and Standards for Recycled Oil-IV, scheduled

for September at NBS.

Wear Standardization and NDE

P. J. Blau, L. K. Ives, F. Matanzo, and A. W. Ruff

One project involves the development and certification of a standard

reference material (SRM) for use with the new Dry Sand/Rubber Wheel

Abrasion Test (ASTM Standard G65-80). Approximately 250 specimens of

D-2 tool steel, the material which was selected for this application,

564-80
have been prepared. Certification tests using NBS equipment have been

completed and the statistical analysis and writing of the certification

statement are expected to be completed this year. An additional 750 SRM

specimens are being prepared for later issue. Publication of ASTM

G65-80, Standard Practice for Conducting Dry Sand/Rubber Wheel Abrasion

Tests, has evoked considerable interest among producers of abrasive wear

resistant materials, manufacturers of equipment subject to abrasive

wear, and users of these materials and equipment. The Dry Sand/Rubber

Wheel wear test is especially applicable for ranking materials exposed

to conditions involving so-called three-body abrasion as might be encoun- tered in earth moving and agricultural equipment, in mining, and certain

ore processing machinery. A Workshop sponsored by ASTM Committee G-2 on Erosion and Wear was held in June for the specific purpose of addressing

problems which might be encountered in applying this Dry Sand/Rubber

Wheel test, and to consider the influence that changes in various test

conditions and parameters might have on test results. The importance of

a suitable calibration specimen was clearly recognized during the course

of this Workshop. We contributed one paper to the Workshop illustrating

the effect of sand flow rate and moisture content on the wear rate using

this test.

Another project is investigating the feasibility of using new metal

processing techniques such as electron-beam (EB) surface melting and

fiber melt spinning to produce microhardness standards. This work was supported by the Office of Standard Reference Materials and was conducted

in conjunction with the NBS Electodeposition Group (D. Lashmore, Materials

Chemistry Division). Electron-beam surface melting techniques developed

in the Metallurgy Division processing laboratory were used on 440C

stainless steel bar stock to see whether areas of sufficient homogeneity

of microhardness suitable for low load micro-indentation testing (0.098

to 0.98 N loads) could be produced. Although the EB zones in the stainless

steel were quite microstructural ly uniform, electroformed Cu-based

materials with a similar microhardness range showed much better reproducibility of microhardness numbers. The decision was made to produce

electroformed Cu standards for this reason. Work continues on characterizing

melt-spun ribbons of Pd80Ge2 o for possible use as standards in other

microhardness number ranges. Additional work on characterizing heat-treated,

electroformed Co-based materials for standards is planned for the coming

year, also in conjunction with the Materials Chemistry Division.

One project supported by the Office of Standard Reference Materials

concerns the development of standards for use with the ferrographic

method of analysis of wear debris particles in lubricants. This method

has proven itself as a viable condition monitoring tool; however, the

quantitative capability involved needs improvement. After participating

in several interlaboratory measurement rounds, it became clear that

certain problems of precision and bias could be overcome if adequate

standards were available. Development of an artificial sample of wear

debris particles and a standard to be used for particle density measurements is now in progress, and should help to further quantify the overall

method.

A project concerned with solid particle impingement erosion has completed

the development of a test procedure that has been accepted by the ASTM

564-81
(Committee level). A final round of interlaboratory testing was also

organized, conducted, and evaluated. Five laboratories participated.

The new standard is the first for conducting erosive wear measurements

under laboratory conditions in the U.S. The typical level of measurement

precision within an experienced laboratory is 5 to 10 percent using this

method.

Quantitative image analysis was employed in a project completed this

year to aid in the development of standardized methods for characterizing

the geometric shapes of sand particles for use in dry sand/rubber wheel

(DSRW) tests. A perimeter ratio (PR) parameter was used to evaluate the

variations in abrasive sand particle shapes in batches of sand used in

testing over a several year period. These ratio parameters remained

very constant from batch to batch in the rounded AFS 50-70 sand specified

for the ASTM DSRW procedure. Sharper particles produced by crushing

quartz and screening it to the same sieve size range as the AFS 50-70

sand had larger PR parameters to start with and produced greater amounts

of abrasive wear on steel samples. Image analysis comparing both used

and unused sand showed that the average PR parameters for AFS 50-70 and

for crushed quartz remained relatively constant before and after the

abrasion tests. However, there appeared to be increases in the standard

deviations of PR parameters of both kinds of abrasives after use in DSRW

tests. Further work is planned using a new image analysis system to

investigate larger sample sizes and to more completely automate the

shape classification procedure. This future work should improve the

statistical significance of PR data by shortening the time required to

analyze larger numbers of particles.

Another project is involved in applying acoustic emission detection

methods to a study of metallic wear in order to monitor particular wear

events such as subsurface crack growth (delamination). While the noise

and vibration background in a typical wear test situation can be complex,

it may be possible to remove such interferences in the detected ultrasonic

signals using filtering, synchronous detection schemes, and computer

based signal procesing. A laboratory bench wear tester has been instrumented with an acoustic detection system and recorder. An incremental

stressing contact geometry is used, and the anticipated emission events

are searched for in synchronism with the load pulses. Three different

steels having varying toughness have been studied; copper has also been

examined briefly, all sliding under lubricated conditions against 52100

steel counterfaces. Some unusual emitted waveforms have been detected

from the steel specimens, but they do not occur with every load pulse.

Digital pulse recording and analysis will be tried next in order to

obtain better resolution of the waveform details. This work is carried

out in coordination with the other acoustic emission work in the Metallurgy

Division concerned with signal analysis and source characterization.

Metallic Biological Implant Materials

Subtask 4 of 12144

A. C. Fraker, G. J. Mattamal , A. C. Van Orden, and C. Olson

The work of this task covers a broad spectrum of activities as is necessary

for investigations in the multidisciplinary field of biomaterials.

564-82
Studies during the past year have dealt with standards, interfaces,

corrosion, corrosion-fatigue, metal ion/protein reactions, surface

modification through ion implantation, and porous coated materials.

These investigations are described briefly in the following paragraphs.

The accomplishments in this task are made possible by the participation

of other people in addition to the regular NBS staff. Other personnel

associated with this task are Dr. M. Ashraf Imam, George Washington

University and the Geotech Corporation, Dr. Pei Sung, Bureau of Medical

Devices, the Food and Drug Administration, Dr. Kirk J. Bundy, the Johns

Hopkins University, college students Alison Bailey (North Carolina State

University) and Jacqueline Smith (Howard University) and student aides,

Christine Schrider and Susan Nossal.

Standards

There is a strong need to develop performance standards for medical and

surgical devices. The test methods developed in ASTM, for example, for

materials can be used for this purpose. This past year the ASTM F746-82,

Standard Method of Test for Pitting or Crevice Corrosion of Metallic

Surgical Implant Materials, was passed. NBS participated for many years

with other university and industrial laboratories in developing this

test and conducting interl aboratory tests. This is the first standard

corrosion test for surgical implant metals, and it will be followed by

the production of the NBS 316L stainless steel standard reference material

(SRM) for use with the standard test. NBS has obtained 316L stainless

steel for use as standard reference material from the supplier who

furnished the round-robin specimens and who supplies implant manufacturers.

Work on the SRM production is underway and some studies to refine the

test are being conducted in terms of effects of solution oxygen content,

solution pH and metal surface condition.

Interfaces

Metallurgical studies of interface bonding on implant alloys are underway

and are supported by the Bureau of Medical Devices, Food and Drug Administration. The purpose of this work is to determine the effects of surface

treatments of metals on interface problems or strength of metal /polymethyl

methrylate (bone cement) interfaces in joint prostheses. A review was conducted of over 200 articles relating to bone cement, cemented prostheses,

forces involved in the loading of the hip joint and other prostheses

installation considerations. This literature review suggests that there

is a discrepancy between the calculated positions of maximum stress

obtained by analysis and those positions where failure is most likely to occur clinically (at the interface). A hypothesis which could possibly

explain this discrepancy is that horizontal forces in the hip have not

been taken into account analytically. If they were it is thought that

the results would indicate that high torsional stresses exist at the

interface (see fig. 4). Thus, studies of the bone cement-metal interface

in torsion are important. The numerous test methods of ASTM D-14 on adhesives were reviewed and found to be inappropriate for testing the

bone cement/metal interface. An appropriate test method involving

torsion loading was developed to the point of application for measuring

bond strength of the cement/metal interface. This test has been upgraded

and is being conducted this summer using a computerized commercial

mechanical testing machine.

564-83
The results of the first year's work have been presented at technical

meetings at the FDA, NBS, and The Johns Hopkins University. The annual

report which was sent to the FDA is being published as an NBS Internal

Report.

Corrosion

Electrochemical measurements are made on implant metals using techniques

of anodic polarization, localized corrosion stimulation, and repassivation.

Studies were continued to investigate the effects of small compositional

changes in Fe and Cr contents on the corrosion behavior of the Co-Cr-Mo

implant alloys. Corrosion measurements were made in physiological

saline solution at 37 °C. Repassivation measurements proved to be the

most sensitive technique and showed that increased Fe content caused the

alloy to have a slower repassivation rate. Analysis of the surface

films using scanning electron microscopy (SEM) and energy dispersive

x-ray analysis (EDX) showed the films on these alloys to be enriched in

Fe, Si, and Mo. These data are especially significant when considering

new standard specifications for composition of implant metal alloys.

Varying or new processing techniques can introduce increased amounts of

metals such as iron, and data are needed to show the effects of these

changes. These data have been supplied to the ASTM F-4 Committee.

These results were presented in talks at the Washington, DC, Bioengineering

Colloquium; at the annual meeting of the Society for Biomaterials,

Disney World, FL; and at the Electron Microscopy Society of American

meeting in Wasington, DC. Further corrosion studies on other implant

alloys involving effects of proteins and details of repassivation processes

are planned.

Corrosion-Fatigue

An important requirement which load-bearing implant metals must meet is

that of high corrosion-fatigue resistance. This is due to the repeated

loading to which they will be subjected and to the aqueous saline environment.

Experiments are conducted to determine the influence of microstructure

and other designated variables on the corrosion-fatigue life of implant

metals when tested under conditions of fully reversed torsion at a constant shear strain amplitude and a frequency of 1Hz in flowing physiological saline solution at 37 °C. Titanium alloys, Ti-6A1-4V and

Ti-4.5Al-5Mo-l.5Cr have superior corrosion-fatigue behavior over the

other implant metals under these testing conditions. Work on the effects

of heat treating on phase composition, microstructure, and fatigue life

of these alloys continues. This is a collaborative effort with the

George Washington University. It was established several years ago that

maximum corrosion-fatigue life for the Ti-6A1-4V is obtained by heat

treating at 900 °C and rapidly quenching. However, this alloy still is

used in the mill annealed condition for implant purposes. Recent

corrosion-fatigue tests of this mill annealed alloy after the surface

was sand blasted showed an increase in corrosion-fatigue life. This

sand blasted material, if improperly heat treated, has very low-fatigue

resistance. The Ti-4.5Al-5Mo-l.5Cr alloy is not an implant alloy but

possibly could be used for this purpose. Corrosion-fatigue tests show

that heat treating this material at 915 °C doubles the fatigue life over

that resulting from five other heat treating temperatures. This is a

564-84
more complicated alloy than H-6A1-4V and heat treating procedures have

not been completed to produce the optimum mechanical properties. This

work is continuing. Other corrosion-fatigue studies are concerned with

Co-Cr-Mo materials after different modes of processing (casting, forging,

hot isostatic pressing, etc.) and with metal porous coated specimens.

Metal Ion/Protein Reactions

Knowledge of the biological response to metal ions is essential for

determining the suitability of a given metal or alloy for use as an implant. Corrosion data and chemical analysis results show that placing

metals in the body results in some metal ion release. Some metals are indicatd as being more harmful than others and nickel is in this category.

Nickel is a constituent of 316L stainless steel, Co-Ni-Cr multiphase

alloy and some other alloys which are used for implant purposes. Laboratory

investigations involving N++ ion interactions with human serum albumin were carried out this year. An ultrafiltration method was used in which

a filter entraps the protein with or without bound metal ions. This was coupled with atomic absorption chemical analysis techniques to determine

the amount of nickel bound to the human blood serum albumin (HSA) molecule.

Results indicated that HSA has approximately 15 identical and negligibly

interacting binding sites for the Ni++ ion in the pH range of 5.6 to 6.3

in unbuffered solution at 37 °C. The pH has a strong influence on the

Ni++ HSA interactions with increased binding affinity occurring with

increasing pH in the pH range studied. These results were presented at

the 1982 annual meeting of the Society for Biomaterials, Disney World,

FL. Additional work is underway to obtain data on nickel ion reactions

and to study other metal ion reactions as they occur or in the presence

of other metal ions. Metal ion release from alloys mostly commonly will

be a combination of several metal ions.

Surface Modification

Titanium and titanium alloys have been ion implanted with boron, carbon,

and nitrogen. This work is being conducted to determine if wear and

mechanical properties of titanium can be improved without sacrificing

the excellent corrosion resistance of titanium. Titanium specimens were bombarded at NBS with the B, C, and N ions to a dosage of 1 x 10 17

ions/cm2 and also at lesser dosages. Anodic polarization measurements

of corrosion behavior showed some changes but no serious detrimental

effects. Transmission electron microscopy and electron diffraction

indicated a highly deformed surface layer. This work was reported at

the October 1981 AIME meeting in Louisvile, KY. Much work remains to be

done relating to the properties and the preservation of the very thin

surface film and this effort is continuing.

Porous metal coatings on metal substrates are being applied on prosthetic

devices for the purpose of obtaining better fixation by ingrowth of bone

and tissue. This fixation is appropriate for people with healthy bone.

This investigation is being initiated to study corrosion-fatigue of the

porous coated material to determine the corrosion behavior and to characterize the interface and the porous coating. This work is being conducted

in cooperation with a local company, the Artech Corporation which applies

the arc plasma sprayed porous coatings.

564-85
Wear Rates (mm3/mm) xIO

-6

at 45

N

Figure 1 Abrasion wear rates for plasma sprayed and electron beam

melted chromium carbide coatings on 2024 aluminum.

564-86
4.0

3.0

2.0

E

10

•o E

E

I „w 0.5

LJ

fe 0.4

ce. < 0.3

LU

0.2

0.1

0.05

12 P,DC

5 P,X

200 400 600 1000 2000

HARDNESS (KHN 500 , kg/mm2

)

Figure 2 Dry sliding wear rates for various nickel -phosphorus alloy

coatings on tool steel vs microhardness.

564-87
Figure 3 Wear volume vs sliding distance for SbSbS4 and other lubricants

on steel

.

564-88
I

I

Figure 4 Total hip replacement prosthesis and applied joint force

components.

564-89
1
CHEMICAL METALLURGY

Task 12145

The interplay between thermodynamic predictive models and the formation

and stability of alloy phases is the central theme of this task's activities.

This--theme is developed in data, theory, and experiment. Conventional

and new experimental techniques are combined with theoretical models in

the determination and prediction of phase diagrams. Special emphasis is

placed on the development of on-line computer graphic systems. In

addition to its fundamental scientific interest, advancement in the

understanding of phase diagrams is essential to permit greater flexibility

in development of new alloys for improved performance, ease of processing,

reduced cost, and energy use, as well as in providing substitutes for scarce elemental additions.

The joint effect mandated by agreement between the Directors of the

National Bureau of Standards (NBS) and the American Society of Metals

(ASM) has continued to provide critically evaluated phase diagram and

other constitution data as well as related bibliographic material.

Technical oversight of this program and work on selected systems is

being carried out by the Alloy Data Center (supported in part under this

task and by the Office of Standard Reference Data (OSRD)). ASM continues

to support a Research Associate at NBS for this project and has initiated

a four million dollar fund raising effort from industry. A quarterly,

Bulletin of Alloy Phase Diagrams, is also published under this program.

The scope of the major effort initiated last year to evaluate binary

phase diagrams at NBS, has been greatly extended to include iron-based

and aluminum-based systems in addition to previously initiated evaluations

of titanium-based systems. Thus, all binary alloy phase diagrams based

on elements of commercial and national interest like Fe, A1 , and Ti are evaluated at the National Bureau of Standards. The projects of compiling

and evaluating phase diagram data for all binary titanium, aluminum and

iron-based alloys have three aspects: (1) to provide accurate phase

stability data compilations; (2) to serve as a model for the rest of the

categories in the NBS/ASM joint program on binary phase diagrams; and

(3) to create a modern computer-based phase stability data compilation.

The program has four basic and interrelated components. These include

compilation and evaluation, development of bibliographic methods, thermodynamic optimization, and development of computer software.

Experimental phase diagram work has been concerned with the binary and

ternary systems relevant to the Ti and A1 rich corner of the quinary

system Ti-Al-Mo-Nb-Ta. This work is being done with the partial support

from the Office of Naval Research (ONR). The Ti alloys involved in this

system have important present and potential practical advantages. Their

high corrosion resistance makes them attractive for marine and chemical

processing applications, and their high strength to weight ratio makes

them valuable in aviation and space technology.

Other activities in this task include theoretical work on understanding

parameters important to alloy phase stability, and a major effort in the

evaluation of possible nonuniformities in two aluminum alloys used by

the National Aeronautics and Space Administration in the Space Shuttle.

564-91
The latter program, while reported under this task, has involved many of

the scientists in the other groups in the Metallurgy Division.

Alloy Phase Stability

Subtask 1 of Task 12145

K. J. Bhansali, L. H. Bennett, J. R. Cuthill, D. J. Kahan, A. McAlister,

J. L. Murray, M. E. Read, L. J. Swartzendruber, and R. D. Shull

We are pursuing a program of three interconnected parts: critical

evaluation and compilation of binary phase diagram data, experimental

work on phase stability on alloy systems selected with a view to complementing the evaluation program, and the theory of phase stability,

stressing the prediction of the heat of formation of transition metal

binary alloys.

Alloy Phase Diagram Data Center Activities

All activities revolve about a collaborative alloy phase diagram critical

evaluation program with the American Society for Metals. At NBS the

scope of the phase diagram program has been greatly extended, to include

not only the Ti category, but also the important categories of A1 and Fe

binary systems. Archie McAlister and Joanne Murray are the joint category

editors for A1 , Lydon Swartzendruber is the category editor for Fe, and

Joanne Murray is the category editor for Ti. This program is active in

the preparation and dissemination of a comprehensive computer-accessible

data base of binary and multicomponent alloy phase stability data. The

data which are to become accessible by computer include not only the

graphical phase diagrams themselves, but relevant metastable equilibria

and thermodynamic properties, an annotated bibliographic data base, and

the text of the evaluation. In order to carry out the critical evaluation of data, an International Council of experts in thermodynamics and

phase stability acts as advisors on the scope and format of the evaluations, supported by additional panels of experts dealing separately with

binary and multi -component systems. The actual evaluation of the phase

diagram data is being carried out througout the world at institutions

with special expertise in certain alloy systems. In addition to evaluations being done at NBS, evaluations are in progress in the categories:

actinides, alkali metals, rare earths, Be, Cu, V, Zn and Cd, Nb, Zr, Mo,

Mg, Co, Cr, hydrides, Ni , Si and Ge, and platinum metals.

The first seven issues of the Bulletin of Alloy Phase Diagrams have been

published. This Bulletin, edited at NBS and published by ASM, is the

main method of rapid dissemination of evaluated phase diagrams produced

by category editors. The Bulletin also has acted as a vehicle for open

review, and comments from the readers are published. New evaluations

are being published from the Ti, A1 , V, Zr, and Cu categories.

Evaluations of binary systems of Ti with all the transition metals

through the Ni-column have been completed. In the Al-category Al-Mg,

-Zn, -Be, and -Li have been completed and -Cd, -Ga, -In, and -Cu are in

progress. In the Fe category, pure Fe and Fe-Ru are in progress. This

work is serving to define the scope and organization of phase stability

data, to provide a role for thermodynamic modeling in both the evaluation

of data and the creation of accurate graphical diagrams. It also has

564-92
stimulated the development of the computer tools required for the establishment of a computer data base organized on sound metallurgical principles. An expansion of the evaluation program to ternary systems is

planned to begin within the next year.

NBS has available computer programs for the calculations and optimization

of phase diagrams from thermodynamic data, and for the on-line graphical

display of phase diagram data input either from a calculation or directly

at the terminal. A new version of the thermodynamic program has been

obtained which will allow us to use the more sophisticated quasi-chemical

and sublattice models; also Dr. Bo Sundman of the Royal Institute of

Technology, Stockholm, has agreed to provide NBS with his program to

optimize multi sublattice free energy functions. Progress has been made

this year in representing both thermochemical and graphical phase diagram

data in a computer file structure suitable for use in a database. Use

has been made of a "list structure" which is program independent, freely

formatted, easily edited, and equally interpretable by human users and

computer programs.

We are advising ASM in the preparation of an on-line phase stability

bibliography. John Cuthill is an ASM Research Associate working on this

data base to be set up at Bibliographic Retrieval Service (BRS). Progress

has been made in the development of formats for the annotation of phase

diagram papers and the dissemination of formats to category editors.

Uniform annotations of the phase diagram literature will allow complete

bibliographies to be retrieved for both broad and limited topics in

phase equilibria.

Experimental Phase Diagram Program

Experimental phase diagram concerned with the binary and ternary systems

relevant to the Ti and A1 rich corner of the quinary system Ti-Al-Mo-Nb-Ta.

This work is being done with partial financial support from the Navy.

The Ti alloys involved in this system have important present and potentially practical advantages. Their high corrosion resistance makes them

attractive for marine and chemical processing applications and their

high strength- to-weight ratio makes them valuable in aviation and space

technology. With better understanding of Ti phase diagrams, it may be

possible to reduce titanium processing costs so that titanium alloys

could substitute for some stainless steels, as a means of reducing the

U.S. dependence on imported chromium. Increased knowledge of Ti alloy

phase formation can provide means of improving weldability.

Experimental work on these Ti-Al systems at NBS has been designed to

overcome the experimental difficulties which have resulted in conflicting

reports of several Ti diagrams in the literature. Contamination easily

occurs in long anneals; principally oxygen cannot be removed, and the

presence of aluminum may make hydrogen removal difficult as well.

Special attention has been given to the production of pure samples; the

oxygen content of samples now being prepared is less than 250 ppm, very

low for Ti alloys. With carefully prepared samples, we have investigated

selected regions of the phase boundaries using transverse-electromagnetic

(TEM), optical metallography, and differential scanning calorimetry

(DSC). Professor R. C. Reno, who is visiting NBS from the University of

Maryland, has made the TEM measurements for these studies. In addition,

564-93
the order/disorder transition in the binary Ti-Al system has been studied

using magnetic susceptibility measurements.

The phases being investigated are the bcc solid solution (p), the disordered hexagonal-close-packed (hep) solid solution (a), and the ordered

hep phase (a 1 ). After precision determinations of the p/a and a/a 1 boundaries had been made in the binary Ti-Al system, the effect of 0.25

and 0.50 a/o Mo a/o on the a/(a + p) and a/a + a' boundaries was monitored;

thus the Ti-Al edge of the ternary Ti-Al-Mo diagram is mapped. For the

first time the order/disorder transition a/a 1 has been monitored using

DSC, and the a/a' transition has been shown to be relevant for the study

of the Ti-6211 alloy.

A Differential Scanning Calorimeter was obtained from Mettler Corporation

for use in detection of solid state phase transformations. It is presently

being modified and calibrated so that this apparatus may be used as a quantitative tool for determining precise transformation temperatures

and for determining heats of transformation. Use of this tool is presently

being made to determine the Ti-Al and the Ti-rich end of the Ti-Al -Mo

phase diagrams.

Other experiments of fundamental significance to phase stability are underway. Metallic glasses and metastable crystalline compounds are one class of material of great interest. They have often been found to

possess more desirable properties (e.g., corrosion resistance, strength,

hardness, and ductility) than their equilibrium counterparts. In pursuit

of this interest, a vacuum melt spinner has been constructed in which

the molten alloy is solidified very quickly by impinging the liquid onto

a copper wheel rotating at a speed of 10,000 rpm. For a glass produced

in a 77 Pd-6 Cu-17 Si alloy, Dr. Moshe Rosen, a visitor to NBS from The

Johns Hopkins University, has succeeded in monitoring its crystallization

by ultrasound velocity measurements.

In conjunction with David Lashmore of the Materials Chemistry Division,

studies of pulsed el ectrodeposi ted amorphous nickel -phosphorus alloys

containing up to 42 at. % phosphorus have been carried out. It was

shown, using nuclear magnetic resonance techniques, that these metallic

glasses exhibit polymorphism, in addition to any continuous structural

relaxation.

Fundamental Theory

In collaboration with Dr. R. E. Watson of Brookhaven National Laboratory,

further advances have been made in the understanding of the quantum

mechanical basis of alloy phase stability. A new correlation has been

discovered for transition-metal alloys, in analogy with the well-known

Hume-Rothery relative valency rule for nontransition-metal alloys. The

relative solid solubility of two transition metals in each other has been

shown to be related to the relative proximity of the components to a halffilled d band. Explanations based on Friedel band theory and on EngelBrewer electron configuration theory have been advanced.

A new understanding of volume effects in transition-metal alloying has

been provided. The relatively modest volume contractions (or expansions)

564-94
occurring on alloying does not correlate well with the heats of formation,

but a useful correlation has been obtained that relates these volume

effects to electronegativity trends. The correlation holds so well for

the bulk of the transition and noble metal alloy systems that it can be

employed to estimate volume effects for cases where they have not been

observed. This should prove of use in calculating enthalpies of alloy

formation.

A new study has been initiated to extend the Turnbull rule for volume

effects in transi ti on-metal -metal loid amorphous and crystalline alloys.

Nondestructive Evaluation of Nonuniformities in 2024 Aluminum Alloy Plate

Relationship to Processing . Subtask 2 of Task 12145

L. K. Ives, L. J. Swartzendruber, W. J. Boettinger, M. Rosen, S. D. Ridder,

F. S. Biancaniel lo, R. C. Reno, D. B. Ballard, and R. Mehrabian

Nondestructive evaluation (NDE) using eddy-current conductivity and

hardness measurements form an essential part of the quality control of

aluminum alloy plates used for aerospace vehicles. The relationship

between the NDE measurements and the important mechanical properties are affected by a large number of variables including: chemical composition;

cast structure; ingot scalping; solution heat treatment and quenching;

mechanical working; and aging treatment. At the request of the National

Aeronautics and Space Administration, a number of these relationships

have been explored for 2024 aluminum alloy. This work is a continuation

of our previous efforts on 2219 aluminum alloy and is motivated by a concern that improperly treated plates with "soft spots" may have been

incorporated into structures on the Space Shuttle. A major result of our research has been a delineation of which alloy tempers and plate

thicknesses are most likely to contain soft spots due to specific processing

errors known to have occurred in a large number of plates.

The present studies include the following:

(1) Studies on as-received material. This includes a 15 cm (6 in.)

plate of 2024-T851, an 0.635 cm (1/4 in.) thick plate of 2024-F,

and a direct chill cast ingot of 2024, all obtained from the Reynolds

McCook plant.

(2) Investigation of the phases and inclusions present in cast 2024

aluminum alloy with the aim of determining the degree of micro- and

macrosegregation and identifying the inclusions present in the

as-cast ingots.

(3) Determination of a set of C-curves which can predict the mechanical

and NDE properties for any type of quench following the solution

heat treatment. Two tempers, T851 and T351, were investigated.

(4) Transmission electron microscope studies of the stable and metastable

phases present an attempt to relate the observed microstructural

changes to the measured changes in mechanical and NDE properties.

564-95
(5) A study of the ultrasonic wave propagation as a function of thermomechanical treatment of the alloy with the objective of establishing

a correlation between ultrasonic data and mechanical properties and

of providing an additional NDE parameter to better characterize the

material

.

(6) A nondestructive evaluation of the age hardening sequence by means

of dynamic eddy-current conductivity measurements.

(7) Use of a heat flow model to calculate almost all conceivable heat

flow conditions anticipated during the quench of 2024 aluminum

alloy plate form the solution heat treatment temperature of 495 °C.

The calculated time-temperature data were then coupled to the

C-curves, and the variations in properties across different thickness

plates for the worst and best heat flow conditions were predicted.

Predictable macrosegregation was obtained in laboratory ingots of 2024

aluminum alloy. It was found that macrosegregation of copper and other

alloying additions in direct chill cast ingots of 2024 aluminum alloy

cannot be completely eliminated by chill face scalping and subsequent

thermomechanical treatment. Although good scalping practice should

maintain compositions within specified limits with no deterioration in

mechanical properties, the macrosegregation remaining in the finished

plate product will contribute to the scatter observed in the NDE measurements. Further, because of the large copper content, variations near

the chill face, surface hardness, and eddy current measurements are necessarily very sensitive to scalping depth in their ability to evaluate

the condition of finished alloy plate.

A large number of samples were taken from a 0.635 cm thick plate of 2024

aluminum alloy in the F temper and processed to the T851, T351, or T4

temper. During processing to these tempers the quench following solution

heat treatment was varied, giving a series of samples with a wide range

of microstructures and hence mechanical properties. A schematic of the

thermomechanical treatments is shown in figure 1. As shown in this

figure, two types of "pre-aging" treatment, labeled sequence A and

sequence B, were used. The hardness, eddy-current conductivity, yield

strength, ultimate tensile strength, elongation, and area reduction of

these samples were measured. The data accumulated were used to construct

a set of approximate C-curves from which the alloy properties can be

determined for any time-temperature cycle of the quench following solution

heat treatment. The C-curves can also be used to generate correlations

between mechanical and NDE properties. An example is shown in figure 2. The C-curves were also combined with time-temperature data from a computerized heat flow model to predict the variations in properties across plates of different thicknesses for both sequence A and sequence B type

pre-aging heat treatments. It was found that the T851 temper is quite

"quench sensitive" in the sense that the ultimate tensile strength

falls below specification for the "worst possible quench" case for very

thin plates.

TEM studies were carried out on a large number of specimens in an 120 kV

instrument equipped to operate in the scanning transmission (STEM) mode

as well as in the conventional transmission mode. The instrument was

564-96
also equipped with an x-ray energy dispersive spectrometer which permits

the determination of elemental composition on a microscopic size scale.

A major objective was to identify those microstructural changes that were responsible for the mechanical and physical properties delineated

in the C-curve representations. Although the microstructure as a function

of presaging is complex, it appears that pre-aging induced precipitates

can contribute to the strength and are subject to overaging during

further heat treatment. This provides a mechanism for the loss of

strength which can account for the fact that the strength of the T851

temper is actually reduced below that of the T351 temper given the same pre-aging heat treatment (rather than being raised as occurs for properly

quenched material).

The objective of the ultrasonic studies was to determine the extent to

which a correlation exists between the mechanical and ultrasonic properties.

For this purpose, the absolute, rather than the relative, values of the

sound velocity and ultrasonic attenuation are required. The data have

to be determined, consistently, to a high degree of accuracy so as to

enable a comparison to be made between specimens of unknown thermal

history, and to correlate these data with the ultimate mechanical

properties of the material. The absolute values of sound velocity and

ultrasonic attenuation were determined to within ± 1 ms

-1 and ± 0.02 dB,

respectively. The extent to which ultrasonic attenuation correlates

with hardness is illustrated in figure 3. The behavior of the ultrasonic

attenuation is correlated with the behavior of the hardness, i.e., softer

material has higher attenuation values. The higher attenuation values

of the B sequence, relative to the A sequence can be explained by a difference in microstructure between the two sequences. These results,

along with the other results mentioned above, have been incorporated

into a final report.

564-97
TEMPERATURE

TEMPERATURE

SOLUTION HEAT TREATMENT

TIME

TIME

Figure 1 Schematic representation of the thermomechanical treatment

sequences given the 2024-T851 and 2024-T351 aluminum alloys.

564-98
ULTIMATE TENSILE STRENGTH US CONDUCTIVITY 2024-T851

80

70

60

50

Xi " " ^ ^ —

g ,

s X

•X

I o

" s

x - sol:

0 - D0T1

DAS*

D LINE

’ED LINE

1ED LINES

: SEQ A

: SEQ B

i SCATTE ? BAND

" - ^ x*

* *

x x

*x :8 o

•J* 5 x

x

•*% X

* V

x

V.

S. — ^ ^ *Ssn* O

s NX

* v v

' N

X

X N

y

V

<?.

v NV % N O > \ X

^<^oo x N~

''d°N

X

X

X

N X

X °o°\

\x°x<

xV

X X \

X X

X

X X

>

k X \ X

X 40

30

38 39 40 41 42 43

CONDUCTIVITY, *IACS

44 45

Figure 2 Comparison of ultimate tensile strength vs conductivity data

for 2024-T851 with the correlations predicted by the C-curves.

The dashed lines are the scatter band 95 percent confidence

level) obtained from a least squares quadratic fit to the data.

564-99
HARDNESS

(

Rockwell

3.50 4.00 4.50 5.00 5.50

ULTRASONIC ATTENUATION (dB/cm)

Figure 3 Variation of the ultrasonic attenuation as a function of

hardness in 2024 aluminum alloy pre-aged by sequences A and B prior to aging.

564-100
Other Activities of the

Metallurgy Division

Invited Talks

Science-Career Opportunities for both Graduate and Undergraduate

Students at the National Bureau of Standards

Science Faculty, University of Puerto Rico, Rio Piedras and

Mayaguez, Puerto Rico

G. J. Mattamal

September 14, 1981

Electrocatalysis on WC and Related Compounds and Alloys

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

A. J. McAlister

October 12, 1981

A Relative Valency Rule for Terminal Solubilities of Transition

Metal-Transition Metal Alloys

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

D. A. Goodman

October 13, 1981

Diffusion Driving Forces Produced by Defect Fluxes

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

J. R. Manning

October 13, 1981

The Role of Convection on Solute Segregation During Alloy Solidification in Microgravity

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

S. R. Coriel 1 October 13, 1981

Gravitational ly- Induced Convection During Unidirectional Solidification

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

R. J. Schaefer

October 13, 1981

Wear Studies on Surface Melted Alloys

Oregon Graduate Center, Beaverton, OR

A. W. Ruff

October 14, 1981

The Bulletin of Alloy Phase Diagrams: A New Resource for the

Metallurgical Community

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

L. H. Bennett

October 14, 1981

564-101
Evaluation of Titanium Binary Phase Diagrams

1981 Fall Meeting of the Metallurgical Society of AIME,

Louisville, KY

J. L. Murray

October 14, 1981

Fundamental Aspects of Rapid Solidification

David Taylor Naval Ship Research and Development Center,

Annapolis, MD

J. R. Manning

October 22, 1981

Metallurgical Considerations in Wear

Oregon Graduate Center, Beaverton, OR

K. J. Bhansali

October 23, 1981

Solidification at High Interface Velocities

American Society for Metals, Oak Ridge, TN

R. Mehrabian

October 29, 1981

Wear Studies on Coated and Surface Melted Alloys

Lehigh University, Bethlehem, PA

A. W. Ruff

November 3, 1981

Real Time Topography with X-Ray Image Magnification

1981 Annual Meeting of the Materials Research Society, Boston, MA

M. Kuriyama

November 16, 1981

Growth Kinetic Limitations During Rapid Solidification

1981 Annual Meeting of the Materials Research Society, Boston, MA

W. J. Boettinger

November 17, 1981

Morphological Stability of Electron Beam Melted Aluminum Alloys

1981 Annual Meeting of the Materials Research Society, Boston, MA

R. J. Schaefer

November 17, 1981

Convective and Interfacial Instabilities During Solidification of

Succinonitrile Containing Ethanol

1981 Annual Meeting of the Materials Research Society, Boston, MA

R. J. Schaefer

November 19, 1981

Studies of Liquid Metal Surface Using Auger Spectroscopy

1981 Annual Meeting of the Materials Research Society, Boston, MA

S. C. Hardy

November 19, 1981

564-102
Dry Sliding Wear Studies of NiP and Cr Coatings on 0-2 Tool Steel

ASTM Committe G-2, Phoenix, AZ

A. W. Ruff

December 9, 1981

Microstructures and Fatigue of Implant Alloys

Johns Hopkins University, Baltimore, MD

A. C. Fraker

February 2, 1982

Metallurgical and Corrosion Research at NBS

Indian Institute of Technology, New Delhi, India

K. J. Bhansali

February 3, 1982

Metallurgical and Corrosion Research at NBS

Indian Institute of Science, Bangalore, India

K. J. Bhansali

February 9, 1982

Metallurgical Considerations in Wear

Indian Institue of Technology, Bombay, India

K. J. Bhansali

February 19, 1982

In Vitro Corrosion Studies of Implant Metals

Washington Bioengineering Group, Bethesda, MD

A. C. Van Orden

March 30, 1982

Growth Kinetic Limitations in Rapid Solidification

Harvard University, Cambridge, MA

W. J. Boettinger

April 8, 1982

Wear Tests to Characterize Recycled Oil

The American Society of Lubrication Engineers, Chicago, IL

L. K. Ives

April 15, 1982

Monitoring the Sliding Contact Conditions in Laboratory Wear Tests

of Metals Using Time-Dependent Variations in Friction Coefficients

Thirty- Fifth Mechanical Failures Prevention Group Symposium,

Gaithersburg, MD

P. J. Blau

'

April 21, 1982

Morphological Stability

Harvard University, Cambridge, MA

S. R. Coriel 1 April 22, 1982

564-103
Nickel (11) Ion Interacitons with Human Serum Albumin

Eighth Annual Biomaterials Meeting, Orlando, FL

G. J. Mattamal

April 26, 1982

The Influence of Small Variations in Composition on the Corrosion

of Cobalt-Chromium Alloys

The Society for Biomaterials, Orlando, FL

A. C. Van Orden

April 27, 1982

Wear Studies on Coated and Surface Melted Alloys

Johns Hopkins University, Baltimore, MD

A. W. Ruff

April 28, 1982

Diffusion-Induced Grain Boundary Migration

The American Ceramic Society, Cincinnati, OH

D. B. Butrymowicz

May 3, 1982

Convective and Interfacial Instability During Unidirectional Upward

Solidification of Succinoni tri le

The American Ceramic Society, Cincinnati, OH

R. J. Schaefer

May 4, 1982

The Bulletin of Alloy Phase Diagrams and CALPHAD a Community Interest

CALPHAD XI, Argonne National Laboratory, Chicago, IL

L. H. Bennett

May 16, 1982

Relative Terminal Solubilities of Transition Metal-Transition Metal

Alloy System

CALPHAD XI, Argonne National Laboratory, Chicago, IL

L. H. Bennett

May 17, 1982

Evaluation and Calculation of the Al-Zn System

CALPHAD XI, Argonne National Laboratory, Chicago, IL

J. L. Murray

May 19, 1982

Wear Considerations for Coatings

Surtech and Surface Coating Exposition

ASM and Chemical Coaters Association, City, ST

K. J. Bhansali

May 19, 1982

Applications of New Ideas in Artificial Intelligence to the Interrogation of Phase Diagram Database

CALPHAD XI, Argonne National Laboratory, Chicago, IL

J. L. Murray

May 20, 1982

564-104
An X-Ray Method for Quantitative Analysis of Hardness Indentations

in Crystals

Microhardness-Related Research Seminar, Gaithersburg, MD

M. Kuriyama

May 25, 1982

Some Unconventional Applications of the Knoop Test Method for Microstructural Analysis

Symposium on Microhardness-Related Research, Gaithersburg, MD

P. J. Blau

May 25, 1982

Morphological and Convective Instabilities During Solidification

Twenty-Fourth COSPAR Meeting, Ottawa, Canada

S. R. Coriell

May 26, 1982

Effect of Test Parameters on Wear Rate

ASTM G-2 Workshop Symposium, St. Louis, MO

L. K. Ives

June 9, 1982

Metallurgical Factors Affecting Galling Wear

Gordon Research Conference on Friction, Lubrication and Wear,

New London, NH

K. J. Bhansali

June 15, 1982

Wear Microstructures

Gordon Research Conference on Friction, Lubrication and Wear,

New London, NH

L. K. Ives

June 15, 1982

Applications of Synchrotron Radiation to Materials Science

Materials Research Council Meeting, LaJolla, CA

M. Kuriyama

July 6, 1982

On the Geometry of Zeroed Polynominals of High Degree

SIAM Meeting, LaJolla, CA

J. A. Simmons

July 18, 1982

Structure of Passive Films on Iron

Inti. Conf. on Electronic and Molecular Structure of Electrode

Electrolyte Interfaces, Logan, UT

G. G. Long

July 25, 1982

Surface Tension of Liquid Metals at Elevated Temperatures

Gordon Research Conference, Meriden, NH

S. C. Hardy

July 28, 1982

564-105
Science Career Opportunities for Gifted Students at the National

Bureau of Standards

American University, Washington, DC

G. J. Mattamal

August 13, 1982

The Influence of Chemical Factors on Alloy Phase Diagrams--Modern

Hume-Rothery Parameters

Alloy Development Workshop, Los Alamos National Laboratory,

Los Alamos, NM

L. H. Bennett"

September 8, 1982

Evaluations of Alloy Phase Diagrams —Experimental Data and Thermodynamic Models

Alloy Development Workshop, Los Alamos National Laboratory,

Los Alamos, NM

L. H. Bennett

September 9, 1982

Division Seminars

The Relationship Between Microstructure, Wear, and Debris

Characteristics

D. C. Furze

Uxbridge, Middlesex, England

October 13, 1981

Electron Metallography Study of Gas-Solid Reactions and Large Strain

Deformation

R. M. Fisher

U.S. Steel Corporation, Monroeville, PA

October 26, 1981

Weld Monitoring for Defects Using Acoustic Emission During Welding

D. W. Prine

GARD, Inc. , Miles, IL

October 30, 1981

Biomaterials and Biomechanics Related Failures of Total Hip Implants

K. J. Bundy

Johns Hopkins University, Baltimore, MD

November 13, 1981

Ultra-High Resolution Chemical Analysis with the Atom Probe

S. S. Brenner

U.S. Steel Corporation, Monroeville, PA

November 23, 1981

Welding Characteristics of Rare Earth and Low Sulfur Steels for Gas

Pipe! ines

H. Muir

University of New South Wales, Sidney, Australia

January 6, 1982

564-106
Biomaterials and Biomechanics Related Failures of Total Hip

Prostheses

K. J. Bundy

Johns Hopkins University, Baltimore, MD

January 12, 1982

Ordering Reactions in Superalloys Based on the Nickel -Aluminum

Molybdenum System

P. L. Martin

Carnegie-Mel Ion University, Pittsburgh, PA

March 31, 1982

Magnetic Properties and Applications of Amorphous Metallic Glasses

R. Hasegawa

Allied Corporation, Morristown, NJ

April 21, 1982

Abrasion Resistant Cast Composite Materials

P. Rohatgi

Regional Research Laboratory for Bhopal, India

May 6, 1982

Coarsening and Microsegregation During Nickel -Base Dendritic

Crystal Growth

T. Z. Kattamis

University of Connecticut, Storrs, CT

May 6, 1982

Microstructure Characterization by ijn situ High Voltage Electron

Microscopy and High Speed X-Ray Topography

T. Imura

Nagoya University, Nagoya, Japan

June 7, 1982

Creep and Diffusion in Metallic Glasses

F. Spaepen

Harvard University, Cambridge, MA

June 17, 1982

Tribology in West Germany

H. Czichos

Bundesanstal t fur Materialprufung, Berl in-Dahlem, West Germany

June 25, 1982

Acoustic Microscopy for Materials Studies

G. A. Briggs

University of Oxford, Oxford, England

July 2, 1982

A Statistical Interpretation of Erosion

D. Andrews

University of Cambridge, Cambridge, England

July 27, 1982

564-107
Technical and Professional Committee Participation and Leadership

American Association for Crystal Growth

S. R. Coriel 1 and R. L. Parker, Executive Committee

American Institute of Metallurgical Engineers

The Metallurgical Society

R. D. Shull, Member

Alloy Phases Committee of the Metallurgical Society

L. H. Bennett, Member, Past Chairman, and Liaison to ASM

Solidification Committee of the Metallurgical Society

W. J. Boettinger, S. R. Coriel 1, S. C. Hardy, J. R. Manning,

R. Mehrabian, S. D. Ridder, and R. J. Schaefer, Members

William Hume-Rothery Award Committee

L. H. Bennett, Member

American Society of Lubrication Engineers

Wear Committee

K. J. Bhansali and L. K. Ives, Members

American Society for Metals

P. J. Blau and A. C. Van Orden, Executive Committee,

Washington, DC Chapter

A. C. Fraker, Executive Committee, Ex Officio,

Washington, DC Chapter

Bulletin of Alloy Phase Diagrams

L. H. Bennett, Editor

D. J. Kahan and M. E. Read, Associate Editors

R. V. Drew, Editorial Assistant

Mass Transport Activity

J. R. Manning, Member

Phase Transformations Committee

R. Mehrabian, Member

Process Modeling Committee

J. R. Manning and R. Mehrabian, Members

American Society for Metals/American Institute of Metallurgical

Engi neers Composite Committee

R. Mehrabian, Member

International Council for the ASM/NBS Program for Alloy Phase

Diagrams

L. H. Bennett and R. Mehrabian, Members

564-108
American Society of Mechanical Engineers

Ad Hoc Working Group on Acoustic Emission, Section 5 J. A. Simmons, Member

Research Committee on Lubrication (Hardfacing and Coatings)

K. 'J. Bhansali, Member

American Society of Mechanical Engineers/American Society for Metals

Wear of Materials Conference Steering Committee

A. W. Ruff, Member and 1983 Vice-Chairman

American Society for Testing and Materials

Al: Steel, Stainless Steel, Related Alloys; Castings

R. L. Parker, Member

B2: Nonferrous Metals and Alloys

S. D. Ridder, Member

B5: Copper and Copper Alloys

M. E. Read and L. J. Swartzendruber , Members

B6: Die-Cast Metals and Alloys

R. Mehrabian, Chairman

B7: Light Metals and Alloys; Aluminum Alloy Ingots and Castings

W. J. Boettinger and R. D. Shull, Members

B9: Metal Powders and Metal Powder Products

J. R. Manning, Member

D32: Catalysts

A. J. McAlister, Member

E04: Metallography

D. B. Ballard, P. J. Blau, and L. J. Swartzendruber,

Members

E04: Task Group on Microhardness Testing

P. J. Blau, Member

E04.03: Phase Diagrams Subcommittee

P. J. Blau, Member

E04. 11.07: Metallography; Electron Metallography; Scanning

Electron Microscopy

D. B. Ballard, Task Group Leader

E42: Surface Analysis

G. G. Long and A. J. McAlister, Members

564-109
E7: Nondestructive Testing

L. H. Bennett and L. J. Swartzendruber , Members

E7.04: Acoustic Emission

J. A. Simmons and R. B. Clough, Members

Joint Task Group on Acoustic Emission; System

Cal ibration

J. A. Simmons, Chairman

E9: Fatigue

J. A. Simmons, Member

Task Group 3 - Residual Stress of Effect in Fatigue

J. A. Simmons, Member

E9.03: Fatigue of Composite Materials

J. A. Simmons, Member

F4: Medical and Surgical Materials and Devices

A. C. Fraker and A. W. Ruff, Members

F4/G1: Joint Section on Corrosion of Implants

A. C. Fraker, Co-Chairperson

G2: Erosion and Wear

A. W. Ruff, Chairman

K. J. Bhansali, P. J. Blau, and L. K. Ives, Members

G2.2: Solid Particle Erosion

A. W. Ruff, Task Group Leader

K. J. Bhansali, Member

G2.3: Wear

K. J. Bhansali, P. J. Blau, L. K. Ives, and

A. W. Ruff, Members

G2.91: Terminology and Definitions

P. J. Blau, Chairman

L. K. Ives, Member

Applied Mechanics Review

R. B. Clough, Member, Review Staff

Florence Review Committee, Review of Scanning Electron Microscopes

D. B. Ballard, Chairman

International Association for Dental Research

G. J. Mattamal , Member

International Journal of Crystal Growth

R. L. Parker, Deputy Principal Editor, Editorial Board

564-110
International Journal of Diffusion and Defect Data

D. B. Butrymowicz, Advisory Board Member

Maryland Institute of Metals

W. J. Boettinger, Executive Board Member

Materials Processing Center, Massachusetts Institute of Technology

R. Mehrabian, Member Advisory Board

Materials Science and Engineering

L. H. Bennett, Editor, Phase Diagram Section

Metallurgical Transactions

L. H. Bennett and R. Mehrabian, Members, Board of Review

Visiting Committee, Department of Metallurgy and Materials Science

Carnegi e-Mellon University

R. Mehrabian and R. L. Parker, Members

National Aeronautics and Space Administration, Space and Terrestrial

Applications Steering Committee, Proposal Evaluation Advisory

Subcommittee

S. R. Coriell, Member

National Aeronautics and Space Administration, Materials Processing

in Space Panel

R. Mehrabian, Member

National Aeronautics and Space Administration, Universities Space

Research Association

R. Mehrabian, Member

National Materials Advisory Board, Committee on Superalloy Powder

Alloys

R. Mehrabian, Member

National Materials Advisory Board, Committee on Materials Substitution Methodology

R. Mehrabian, Liaison Member

National Materials Advisory Board, Committee on Rapid Solidification

Processi ng

R. Mehrabian, Chairman

National Science Foundation, Facilities Subcommittee of the

Materials Research Advisory Board

G. G. Long, Chairman

Society of Automotive Engineers/American Society of Testing and

Materials Unified Numbering System for Metals and Alloys

L. H. Bennett, NBS Representative

564-111
Society for Biomaterials Standards

A. C. Fraker, Chairperson, Representative

Society for Experimental Stress Analysis

Residual Stress Committee

C. J. Bechtoldt and J. A. Simmons, Members

Society of Rheology

R. Mehrabian, Member

US-USSR Technology Exchange Agreement

Sub-Committee on Electro-Slag Remelting

R. Mehrabian, Member

Welding Research Council, Committee on Hardfacing and Wear

K. J. Bhansali, Member

Publ i cations

Boettinger, W. J. Conference on rapidly quenched metals. J. Metals

33: 21; 1981.

Boettinger, W. J. ; Biancaniel lo, F. S. ; Coriell, S. R. Met. Trans.

12A: 321; 1981.

Goodman, D. ; Waterstrat, R. M. Comments of the Mn-Fe and Mn-Cr phase

diagrams. Bull. Alloy Phase Diagrams 2: 299; 1981.

Yoo, K. C. ; Roessler, B. ; Armstrong, R. W. ; Kuriyama, M. Scr.

Metal 1. 15: 1245; 1981.

Black, D. R. ; Ballard, D. B. Sputter coated carbon for SEM perfor- mance testing. Bailey, G. W. , ed. Proceedings of the 40th annual

electron microscopy society of America meeting; 1982 August 9-13;

Washington, DC. Claitor's Publ.; 1982. p. 750.

Boettinger, W. J. ; Dobbyn, R. C. ; Burdette, H. E. ; Kuriyama, M. Real-time topography with x-ray image magnification. Nucl. Instrum.

Methods, 195: 355; 1982.

Harris, J. S. ; Ives, L. K. ; Peterson, M. On the lubrication mechanism

of SbSbS^. Bailey, G. W. , ed. Proceedings of the 40th annual electron

microscopy society of America meeting; 1982 August 9-13; Washington, DC

Claitor's Publ. 1982. p. 530.

Kuriyama, M. ; Boettinger, W. J. ; Cohen, G. G. Synchrotron radiation

topography. Annu. Rev. Mater. Sci. 12: 23; 1982.

Nutt, S. R. ; Ruff, A. W. Microscopic studies of sliding wear on titanium. Bailey, G. W. , ed. Proceedings of the 40th annual electron

microscopy society of America meeting; 1982 August 9-13; Washington, DC

Claitor's Publ. 1982. p. 528.

564-112
Olson, C. D. SEM analysis of clad-ceramic coatings after hot corrosion

testing. Bailey, G. W. , ed. Proceedings of the 40th annual electron

microscopy society of America meeting; 1982 August 9-13; Washington, DC.

Claitor's Publ. 1982. p. 522.

Piccone, T. ; Butrymowicz, D. ; Newbury, D. ; Manning, J. ; Cahn, J. Diffusion- induced grain boundary migration in the Cu-Zn system.

Scr. Metal 1. 16: 839; 1982.

Ruff, A. W. ; Lashmore, D. L. Dry sliding wear studies of Ni-P and

Cr coatings on 0-2 tool steel. Am. Soc. Test. Mater. Spec. Tech.

Publ. 769; 1982. 156 p.

Schaefer, R. J. ; Coriell, S. R. Materials processing in the reduced

gravity environment of space, Guy E. Rindone, ed. , Elsevier, 1982,

p. 479.

Van Orden, A. C. ; Chidester, J. L. ; Fraker, A. C. ; Sung, P. SEM studies

of Co-Cr-Mo surgical implant alloy corrosion behavior. Bailey, G. W. , ed

Proceedings of the 40th annual electron microscopy society of America

meeting; 1982 August 16-19; Washington, DC. Claitor's Publ. 1982. p. 520

Bennett, L. ; Watson, R. Atomic volumes in transition metal-metalloid

crystalline and glassy alloys. Scr. Metall . ; in press.

Bhansali, K. J. ; Mehrabian, R. Abrasive wear of aluminum matrix

composites. J. Metals; in press.

Blau, P. J. A comparison of micro- indentation hardness test methods

using Cu, 52100 steel and an amorphous Pd-Cu-Si alloy. Metallography;

in press.

Blau, P. J. Test of a rule of mixtures for dry sliding friction of

52100 steel on an Al-Si-Cu alloy. Wear; in press.

Blau, P. J. Monitoring the sliding contact conditions in laboratory

wear tests of metals using time dependent-variations in friction

coefficients. Early, J. G. ; Shives, T. R. ; Smith, J. H. , eds. Proceedings of the 35th mechanical failures prevention group meeting; 1982

April 20-22; Gaithersburg, MD. Cambridge U. Pr. ; in press.

Boettinger, W. J. Growth kinetic limitations during rapid sol idfi cation. Keart, B. H. ; Giossen, B. C. , eds. Chapter in Rapidly solidified

amorphous and crystalline alloys; New York, NY: Elsevier North Holland;

in press.

Butrymowicz, D. ; Cahn, J. ; Manning, J. ; Newbury, D. ; Piccone, T. Diffusion-induced grain boundary migration. Chapter in Grain boundaries and interfaces in ceramics, Vol. 15. Huer, A.; Yan, M. , eds.

New York, NY: Plenum Press; in press.

Chang, J. ; Nadeau, R. ; Rosen, M. ; Mehrabian, R. Crystallization

kinetics study of amorphous Zr^gCu^^ by means of ultrasonic

measurements and microhardness. Scr: Metall.; in press.

564-113
Clough, R. ; Wadley, H. Indentation loading studies of acoustic

emission from temper and hydrogen embrittled A533B steel. Metal 1. Trans. A; in press.

Coriell, S. ; Boisvert, R. ; Mickalonis, J. ; Glicksman, M. Morphological

and convective instabilities during solidification. Malmajec, Y. , ed.

Proceedings of the 24th COSPAR meeti ng--advances in space research;

1982 May 16-June 2; Ottawa, Canada. Pergamon Press; in press.

Coriell, S. ; Sekerka, R. Oscillatory morphological instabilities due

to non-equilibrium segregation. J. Cryst. Growth; in press.

Coriell, S. R. ; Turnbull, D. Relative roles of heat transport and

interface rearrangement rates in the rapid growth of crystals in

undercooled melts. Acta Metall.; in press.

Goodman, D. A.; Bennett, L. H. ; Watson, R. E. Relative valency

effects in transition metal alloys. Scr. Metall.; in press.

Hardy, S. C. ; Fine, J. Studies of liquid metal surfaces using Auger

spectroscopy. Proceedings of the symposium on materials processing

in the reduced gravity environment of space; 1981 November 16-19;

Boston, MA. Elsevier North Holland; in press.

Ives, L. K. A method for preparing cross sections of wear surface

films i_n situ for TEM study. Wear; in press.

Kuriyama, M. ; Cohen, G. X-ray extinction theory in the Bragg geometry.

Z. Naturforsch. 37a: ; 1982; in press.

Long, G. G. ; Kruger, J. ; Black, D. R. ; Kuriyama, M. Structure of passive

films on iron using a new surface-EXAFS technique. Hansen, P. W. N. , ed.

Proceedings of the 1st international conference on electronic and

molecular structure of electrode-electrolyte interfaces; 1982

July 25-30; Sagan, VT ; in press.

Manning, J. R. Application of phase diagram information to alloy

diffusion coatings. Bull. Alloy Phase Diagrams; in press.

Mattamal , G. ; Kishore, K. Structure-viscosity relationship in some

high molecular weight esters. J. Polym. Sci.; in press.

Murray, J. L. Calculations of stable and metastable equilibrium

diagrams of the Ag-Cu and Cd-Zn systems. Metall. Trans. A; in press.

Oehl , C. ; Swartzendruber , L. On the optimum applied field for magnetic

particle inspection using direct current. Mater. Eval . ; in press.

Parker, R. L. Ultrasonic measurement of solid/liquid interface position

during solidification and melting of metals. Chapter in Applications

of physics to the steel industry. Schwerer, F. , ed. New York, NY: American Institute of Physics; in press.

564-114
Schaefer, R. J. ; Coriell, S. R. Convective and interfacial instabilities during solidification of succi nonitrile containing ethanol.

Rindone, G. E. , ed. Proceedings of the symposium on materials processing in the reduced gravity environment of space; 1981 November 16-19;

Boston, MA. Elsevier North Holland; in press.

Schaefer, R. J. ; Coriell, S. R. ; Mehrabian, R. ; Fenimore, C.

Biancaniello, F. Morphological stability of electron beam melted

aluminum alloys. Kear, B. H. , ed. Proceedings of the symposium on rapid

solidified amorphous and crystalline alloys; 1981 November; Boston, MA;

in press.

Wadley, H. N. G. ; Simmons, J. A.; Stockton, C. K. Dynamic elastic

displacments due to pulsed laser absorption at the surface of an infinite plate. J. Acoust. Soc. Am.; in press.

Watson, R. E. ; Bennett, L. H. Volume effects in transition metal

alloying. Acta Metal!.; in press.

Watson, R. E. ; Bennett, L. H. ; Goodman, D. A. ; A d-band bonding

theory of the relative solubilities of transition metal alloys.

Phys. Rev.; in press.

Special Reports

Mehrabian, R. ; Persh, J. Report on the first workshop on rapid solidification technology. Nat. Bur. Stand. (U.S.) NBSIR 81-2439; 1982. 52 p.

Ives, L. K. ; Peterson, M. ; Harris, J. S. ; Boyer, P. A.; Ruff, A. W. Investigation of the lubrication mechanisms of the complex metal

sulfide, SbSbS

4

. Nat. Bur. Stand. (U.S.) NBSIR 82-2545; 1982. 69 p.

Manning, J. R. NBS: materials measurements. Nat. Bur. Stand. (U.S.)

NBSIR 82-2560; in press.

Sponsored Conferences

Process Control Sensors for the Steel Industry

NBS, Gaithersburg, MD

July 27-28, 1982

R. Mehrabian, Member, Coordinating Committee

Industrial Interactions

Other Industrial Guest Workers at CMS

Wuhan Research Institute of Materials Protection, Wuhan,

Peoples Republic of China/Ximing Meng/A. W. Ruff

Work concerned the wear of steels of different chemical and

mechanical properties. Results were a direct contribution to our Wear Durability Program, as well as to the guest worker's

organization interests.

564-115
Archival Technical Papers Coauthored With Industrial Employee

Characterization of Wear Surfaces and Wear Debris/A. W. Ruff

and L. K. Ives

W. A. Glaeser, Battel le Columbus Laboratories

Wear of Materials - 1981/A. W. Ruff

S. K. Rhee, Bendix Research Laboratories

K. C. Ludema, University of Michigan

Formal Visits to NBS by Industrial Management or Policy Making

R&D Personnel or by NBS Managers to Industrial R&D Sites

Montreal Engineering Co. /October 21, 1981

Discussed erosive wear measurement techniques and apparatus

designs, including new standard method.

Anaconda Industries/October 27, 1981

Visited NBS to discuss Diffusion in Metals Data Center and

diffusion in copper alloys.

Artech Corp. /November 2, 1981, November 30, 1981

Visits have been exchanged with NBS on several occasions to

discuss mutual interests in metal coatings.

Glacier Metal Corp. /November 30, 1981

Visited NBS to learn our wear test methods, wear data, and

effects of metallurgical variables.

Anaconda Industries/February 22, 1982

Discussed wear of metals (copper alloys) and appropriate

methods for laboratory testing.

Fairchild Industries/February 24, 1982

Visited NBS to discuss diffusion in alloys used for Sterling

engi nes.

General Electric Research Lab. /April 24, 1982

Visited NBS to discuss galling wear and metallurgical effects.

International Business Machines/May 5, 1982

Visited NBS to discuss grain boundary diffusion in metallic

syterns.

Bendix Advanced Research Lab. /May 12, 1982

Visited by A. W. Ruff to discuss wear testing methods.

Westinghouse Electric Corp. /May 19, 1982

Visited NBS to discuss wear test needs in U.S. and effect of

environments on wear.

Hughes Research Laboratories/May 25 - June 4, 1982

Visited NBS to discuss theory of phase transformations and

interfacial energies.

564-116
Engelhard Industries/July 7, 1982

Visited NBS to discuss rapid solidification and metals

processi ng.

Continental Can Company/July 29, 1982

Visited NBS to discuss galling wear in forming can shapes

with dies.

Participation in Measurement Programs Involving Substantial

Industrial Cooperation.

Participated in ASTM interlaboratory test series on erosive

wear with personnel from Eastman Kodak, Union Carbide, Cabot

Corporation.

Chairing newly formed task group on galling wear under Wear

Subcommittee ASTM G-02 Committee on Erosion and Wear.

Microhardness Round Robin Test Participant for ASTM E-4.05

Subcommittee.

Participated in several round robins for ASTM with implant

manufacturers.

In November 1981, participated in interlaboratory test series

involving F746-82 Pitting and Crevice Corrosion Test Method

with nine other laboratories, including Cabot Corp. , Cardiac

Pacemakers, Inc., Strauman Institute, Richards Manufacturing

Co., Howmedica, Inc., and Zimmer U.S.A.

Data Programs with Substantial Industrial Support and/or

Guidance

Agreement between International Copper Research Association

(INCRA) and the National Bureau of Standards (NBS) that a 500

page volume prepared by the NBS Diffusion in Metals Data Center

on "Mass Transport and Diffusion in Copper Alloys" will be

published by INCRA as part of the INCRA Metallurgy of Copper

Series. INCRA also shared in the costs for the copper data

evaluations and preparation of this manuscript.

The Alloy Phase Diagram Data Center within the Chemical Metallurgy Group works closely with the American Society for Metals

under the joint ASM/NBS agreement. Technical evaluations and

reviews of the alloy phase diagram data are performed at NBS

and published in the Bulletin of Alloy Phase Diagrams by ASM.

Financial support and guidance from industry is sought by ASM.

Formal Advisory Activities for Industrial Institutions

A. W. Ruff is a member of the Technical Advisory Committee for

the Metals Properties Counsel.

564-117

REACTOR RADIATION DIVISION (566)

Robert S. Carter, Chief

Tawfik M. Raby, Deputy Chief

T. L. Mangum, Secretary

The National Bureau of Standards reactor (NBSR) is a national center for

the application of reactor radiation to a variety of problems of national

concern. The major areas of activity are:

Materials Characterization

Nondestructive Evaluation

Trace Analysis

Radiation Standards and Measurement

The Reactor Radiation Division (RRD), in collaboration with other scientists within the Center for Materials Science (CMS), and other NBS

Centers, and outside organization conducts long term research using

neutron scattering methods to determine the properties and behavior of

materials at the atomic level. These methods are used to study a wide

variety of problems such as hydrogen in metals, the microstructure of

rapidly solidified materials, microscopic properties of advanced crystalline and amorphous magnetic materials, polymers, molecular species and

interactions on catalytic surfaces, and the structure of biological

molecules. These measurements have wide generic applications to understanding of hydrogen embrittlement of metals, alloys and magnetic

materials, ceramics and fast- ion conductors, polymeric structure, chemical

catalysis, and biological processes. NBS is in an unique position to

carry out such a multidisciplinary program because of its strong materials

programs centered in CMS and other centers and its unique reactor facilities that are not available in industrial laboratories.

In the area of nondestructive evaluation (NDE), RRD uses neutron radiography

and both large and small -angle neutron diffraction to examine objects

for defects or hidden components that must be examined nondestructi vely.

The major effort is in the development of neutron methods for nondestructive evaluation. Methods are being developed for such diverse applications as the use of autoradiography to study rare paintings and the use

of neutron scattering to investigate the properties of rapidly solidified

alloys. This program is partially funded through the Office of Nondestructive Evaluation and is part of the Bureau-wide effort to improve productivity through better quality assurance and increased component lifetime.

Neutron activation analysis is a very sensitive technique for measuring

trace elements at very low concentrations. RRD provides the sample

irradiations, but the program and sample analysis is carried out by the

Center for Analytical Chemistry. It is used extensively for characterizing Standard Reference Materials (SRM) and a variety of other measurements such as the determination of impurities in solar cell materials

and environmental studies. A large number of outside organizations also

use this technique for measuring trace elements or pollutants in foods

and drugs, environmental samples, criminal artifacts, etc. This is one

of the largest neutron activation analysis activities in the country

with many thousands of samples irradiated each year. Although the

566-3
primary effort in this activity is centered around neutron activation

analysis, other neutron analytical methods are also being developed. A

facility has been built to analyze for trace elements by measuring the

prompt gamma ray spectrum induced by neutron capture in the sample, and

a method has been developed (depth profiling) to measure concentrations

o of light elements as a function of depth with 100 A depth resolution.

The program in radiation standards and measurements is carried out by

the Center for Radiation Research (CRR). Through the use of double

fission chambers and a series of accurately calibrated fission foils,

they provide the basis for reactor neutron flux and power density measurements needed in the U.S. fast-flux development program. The calibration

and intercomparison of the series of fission foils makes use of standard

reference neutron fields established in the thermal column of the NBSR.

CRR also maintains well characterized, filtered neutron beams in the

reactor of 2 keV, 25 keV, and 144 keV energy for the calibration and

development of personnel neutron dosimeters.

A number of other programs both within and outside NBS utilize the

long-term irradiation facilities at the NBSR for activities ranging from

y-ray and x-ray physics and standards to applications of isotopes in

medical diagnosis.

As is indicated above, RRD has a dual function. It conducts research

programs in the areas of materials characterization and nondestructive

evaluation and serves as a focal point of neutron scattering

expertise for many other programs within and without the Bureau. The

second function includes not only the operation of the reactor, but also

providing sample irradiation services for a large number of users.

An important part of the overall Reactor Radiation Division's contribution to the NBS mission and to the scientific and technical community is

in fostering the utilization of the reactor by other NBS groups and

outside organizations. Interactions with other scientists and organizations take the form of both collaborative efforts and independent programs

which rely on utilization of the reactor and facilities provided by the

NBSR staff. The extent of such interactions for FY82 are indicated in

the tables below. The number of personnel shown in tables 1 and 2

include many short-term collaborators as well as permanent other agency

and university guest workers. These numbers are constantly changing and

so may not be exact.

Collaborative interactions are those in which workers from outside the

RRD collaborate scientifically with RRD scientists on problems of mutual

interest. These interactions are summarized in table 1.

These tables demonstrate the extensive utilization of the NBS reactor by

scientists and engineers from outside the Division. They come from 18

NBS Divisions and offices, 30 Government and industrial laboratories,

and more than 20 universities.

Many of the other agency and university collaborators have worked with

us regularly for many years. Five of them (two from the Navy and three

from the Army) are assigned to work full time at the reactor on a permanent

566-4
Table 1. Collaborative Interactions

No. of Personnel

FY82

RRD Permanent Scientists 12

Non-RRD Participants

Other NBS 22

Other Agency 32

University 27

Industrial 12

Total Non-RRD 93

Independent programs are those programs carried out independently of the

Reactor Radiation Division scientific staff by other NBS Divisions and

outside organizations. Table 2 summarizes these interactions.

Table 2. Independent Programs

No. of Personnel

FY82

Other NBS 28

Other Agencies 23

Universities 17

Industrial 4

Total 72

basis. Others regularly spend two or three days a week at the reactor.

Bureau collaborative programs include measurements on fast- ion conductors,

polymers, catalytic materials, hydrogen embrittlement, voids and precipitates in alloys, etc.

The two major independent (non-col laborative) Bureau programs are trace

analysis by neutron activation analysis run by the Center for Analytical

Chemistry and standard neutron fields for neutron flux calibration and

materials dosimetry in the Center for Radiation Research. Although

these activities are included in more detail with all the other activities

at the reactor in the reactor annual report, NBS Reactor: Summary of

Activities, 1 a few highlights will be given here.

The neutron standards and dosimetry program utilizes three filtered

neutron beams, one thermal beam from the thermal column, and a cavity in

the thermal column in which they can establish several types of wellcharacterized neutron fields. Typical projects include:

1 Copies of this summary for July 1981- June 1982 will be made available

to Panel Members prior to the meeting.

566-5
• Intercomparison of flux parameters for filtered beams at the NBS

reactor with those at Physi kal isch-Technische Bundesanstal t, the

West German Standards Laboratory at Braunschweig.

• Fission cross section measurements in the Intermediate-Energy

Standard Neutron Field (ISNF) for U-233, Pu-240, Pu-241, and Th-232.

• Quality control tests for Navy shipboard area neutron dosimetry

monitors.

• Systematic performance testing of essentially all types of personnel

neutron dosimeters used in the U.S.

• Preparation of neutron fluence standards at the cavity fission

source for calibration of a dosimetry counting system at Oak Ridge

National Laboratory, TN.

The neutron activation analysis program primarily uses the irradiation

services of the reactor to irradiate samples for trace analysis. They

also develop other analytical neutron methods. Only the most recently

developed one, depth profiling, will be summarized.

Depth profiling is the determination of the amount and depth profile of

elements such as helium, lithium, and boron in metal and semiconductor

substrates. The depth distributions of such elements are of interest

for first-wall fusion reactor design and for diffusion into metals. The

distribution of lithium and especially boron in semiconductors is, of

course, of great concern to the electronics community.

The depth profiling technique using thermal neutron beams involves

illuminating a target with a beam of thermal neutrons and measuring,

with an energy-dispersive detector (silicon surface barrier), the energy

distribution of the charged particles produced. Since the incident

neutron energy is completely negligible compared to the reaction Q- value

(E

q ), the charged particles produced are both monoenergetic and isotropic.

Those particles which escape from the sample lose energy along their

exit path at a known rate dE/dx. The energy distribution of these

particles at a fixed escape geometry is measured by a silicon surface

barrier detector. When subtracted from the initial energy (E

q

), the

energy loss distribution is obtained, which can be directly related to

the depth distribution of the parent isotope via the known stopping power.

o Sensitivities of 10 15 atoms/cm3 and depth resolutions of 100 A are obtainable.

An exploratory project was initiated in this area three years ago and

has now reached fruition in an excellent facility using a dedicated beam

at the reactor. A high quality neutron beam with an intensity of

3 x 108 n/cm2 -s is achieved using a room temperature filter of 20 cm of

sapphire and 8 cm of silicon single crystals. Characterization of the

facility is now underway.

566-6
The Nuclear Regulatory Commission's (NRC) review of the NBS 20 MW license

application continues slowly. The Draft Environmental Statement mentioned

in last year's report to the Panel was issued for public comment by the

NRC in January 1982. A few comments were received, mostly from other

agencies. These have been addressed and the final Environmental Statement

will probably be issued some time in September. The other report that

must be completed by NRC is the Safety Evaluation Report (SER) on which

work was begun in July 1982 after a six-month delay. The final license

is not expected before January 1983.

The procurement of reactor fuel from the new vendor, Babcock & Wilcox,

appears to be on schedule. They have completed their facilities on schedule and are already assembling some fuel elements for NBS.

The scientific work of the Reactor Radiation Divison and its collaborators

is summarized later in this report and details are given in the Summary

of Activities mentioned above. A few highlights will be given here to

indicate the current direction and accomplishment of the Division.

During the past year, as part of the Division's Advanced Neutron Methods

competence initiative, the NBS small -angle neutron scattering (SANS)

facility has become fully operational, with the installation of the 64 x 64 cm detector along with the implementation of computer-controlled

systems for automatic sample changing (up to four samples) and temperature control, and further development of data analysis and display

programs linked to the technicolor graphics system. A great deal of

exciting new SANS research has been carried out, ranging from the first

direct observation of microcracks in bulk ceramics, to studies of polymersurfactant interactions with industrial scientists, to the nondestructive

evaluation of creep-induced cavitations in stainless steel. This extensive work has involved cooperation with four CMS Divisions, seven industrial and Government laboratories and ten universities from the U.S. and

abroad. In the area of inelastic scattering, our new neutron time-offlight facility has become fully operational, and experiments have been

initiated on the investigation of chemisorbed species on metal particles,

and on the phonon spectra of hydrogen dissolved in metals.

Major accomplishments in our other research and measurement tasks include

a systematic study of the vibration spectra of hydrogen isotopes in

palladium down to the 0.2 percent level, which provides: (1) an anomalous

isotope shift in the solute (a) phase which is the same as that observed

for superconducting (p-phase) palladium hydride and may have an impact

on the theory of superconductive behavior in palladium alloy hydrides

and (2) observation for the first time of an anomalous phonon splitting

due to a chemically equivalent light atom defect in a metal. In addition,

previous RRD neutron measurements on hydrogen trapped by atomic oxygen

and atomic nitrogen impurities in niobium have allowed establishment of

an atomic scale trapping mechanism decidedly different than those previously proposed. Neutron scattering investigations with the Center for

Chemical Physics of chemical species and reactions on metal catalysts

has been extended to studies of carefully processed platinum particles

and have led to discovery of, for example, different binding states for

hydrogen chemisorbed on "unperturbed" platinum sites compared to sites

566-7
containing oxygen impurities. Continuing research on magnetic and

amorphous alloys in cooperation with the Naval Research Laboratory (NRL)

and Bell Laboratories has established the existence of highly anisotropic

propagating magnetic modes in HoA 1 2 and has shown that two kinds of magnetic order exist within FeNi glassy alloys, each associated with a different time scale.

In continuing materials structure and database activities RRD has completed

a number of essential studies of atomic scale structure and microscopic

properties of prototype or tailored oxide compounds with generic application to small batteries and other electronic applications (in cooperation,

with the Materials Chemistry Division, Bell Laboratories, and Massachusetts

Institute of Technology); corrosion inhibitors (with 3M Co.); electroytic

products related to storage-battery lifetime; zeolyte catalysts (with

E. I. Dupont de Nemours, Inc.); and cancer drugs (with the Food and Drug

Administration). Systematic x-ray or neutron studies have also been used

to study the effects of compressive stress on the separate components of

bulk composites (Si-Al), and as part of an effort to identify critical

feedstock properties for quality control in the production of cellulose

compounds. In the Crystal Data Center this past year, a formal agreement

was established with the International Centre for Diffraction Data to

expedite transfer of the Crystal Data Identification file to the chemical

and materials communities via magnetic tapes, designed a new matrix

method for critical evaluation of symmetry, and added 2000 metal and

intermetallic data entries to the master database. Finally in a joint

effort with the Smithsonian Institution to develop neutron-autoradiography

methods, design of a major new facility with extremely high neutron to

x-ray intensity ratios has been completed and several test radiographs

on rare art works have been accomplished.

Plans for the coming year include expanded work in the development of

SANS as a nondestructive probe of distributed damage (voids, cracks,

segregations) in bulk metals and ceramics and continued emphasis on cooperative research with other CMS Divisions and industrial labs on using neutron methods for applications in processing science and durability,

including a first attempt to study the atom scale behavior of hydrogen

at < 10 ppm in iron and steel. Emphasis will also be given to fundamental

studies of short-range order, transformations and spin dynamics of

technologically attractive amorphous alloys and spin glasses, using SANS

and high-resolution inelastic scattering methods. Cooperative research

on catalytic reactions on metal surfaces will be extended to attempt

unique measurements of metal surface vibrations and the rotational

behavior of molecular fragments. Finally in the data programs, publication of two volumes of Crystal Data for organic materials is anticipated.

566-8
REACTOR OPERATIONS AND SERVICES

Task 12161

The reactor was operated on a normal round-the-clock schedule for the

entire year. Other than scheduled shutdowns for maintenance, refueling,

testing, and for staff vacation, there were no interruptions in the

operating schedule. A program of modernization of reactor components

and instrumentation which started last year is continuing. Licensing

activities to upgrade reactor power to 20 MW and renew the operating

license are progressing. A Draft Environmental Impact Statement has

been published by the Nuclear Regulatory Commission as required by

regulations. A final statement will be issued later this year. The NRC

is also preparing a safety evaluation report of the NBS submittals. In

this connection NBS provided extensive additional information to NRC to

assist in their review. A new license will be issued by the NRC, once

the Environmental Impact Statement and the Safety Evaluation Report are published. The new license authorizing increased power and valid for a period of 20 years is expected in early 1983.

Utilization of the reactor continued to be extensive and wide-ranging.

More than 125,000 instrument hours involving 25 simultaneously operable

experimental facilities have been provided to more than 50 organizations

from within and outside NBS.

Reactor Operations

Subtask 1 of Task 12161

T. M. Raby and J. F. Torrence

Over the past year, the reactor was on-line nearly 80 percent of the

time and operating at full power 73 percent of the time. This is about

the maximum efficiency that can be achieved with the available staff.

Once again a remarkable improvement in fuel utilization efficiency was realized by use of new higher loaded elements. An efficiency increase

of nearly 50 percent resulting in an average fuel burnup of 65 percent

is the best in the history of the facility and has already resulted in a significant fuel cost savings. A summary of the overall operating

statistics for the period July 1, 1981 to June 30, 1982 is presented in

the following table.

NB5R Operating Summary FY81

On-line time at 10 MW

Average U-235 burnup

Number of Irradiations

Hours of Irradiations

Hours per Irradiation

Number of days at 10 MW 268

73%

65%

3450

3100

0.9

566-9
Irradiation Service

Subtask 2 of Task 12161

N. A. Bickford and J. H. Ring

Heavy utilization of the reactor for activation analysis and irradiation

services continued this year. The number of irradiations increased by more than 30 percent. Tens of thousands of specimens, involving foods,

drugs, environmental monitoring, geological and mineral examinations,

forensic investigation, and development of standard reference materials

were irradiated at the NBS reactor.

Engineering Services

Subtask 3 of Task 12161

J. H. Nicklas and R. S. Conway

In addition to regular engineering and design services provided to

reactor operations, experimenters, and users, the engineering staff was involved in a comprehensive program of reactor modernization. A contract

has been signed for a fire suppression system for the new cooling towers.

The water treatment building and loading ramp for chemical treatment of

the secondary water has been out for bid and is in the negotiation

stage. A contract to fabricate new shim arm poison blades has been let.

Tooling for this type of control rod was developed and used at Argonne

National Laboratory and will be used for this fabrication. Shim arm yokes, arbors and bearings are in the process of fabrication. Redesign

of the regulating rod for 20 MW operation has begun which will provide a smoother and more reliable regulating rod operation. A new fuel element

contractor has been selected by the Department of Energy (DOE) and has

made an NBSR prototype fuel assembly and a production prototype. Fabrication of actual fuel assemblies will begin when parts have been received

from the sub-contractor.

Extensive effort was expended to implement the modernization program for

the reactor instrumentation. This program replaces old equipment with

more modern reliable console readout devices. For example, the miniature

process recorders provide a faster response indication with the benefit

of easy-to-replace ink cartridges and a much simpler chart roll cassette.

The nuclear indication has been expanded to provide the operator with a console meter for each power range and recorded information for both

start-up channels and intermediate channels continuously.

Nuclear power supplies were replaced by updated versions that meet all

the safety and reliability requirements of the old ones and, in addition,

provide over-current and over-voltage protection. The replacement of

individual shim arm position indicators provides the operator with a readout capability of 1/100 of a degree.

566-10
NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR ADVANCED TECHNOLOGIES

Task 12162

This task develops and applies advanced neutron scattering methods and

related theoretical analysis for research on the microscopic properties

of materials which affect their use in technological applications.

Current areas of emphasis include hydrogen in metals, new magnetic and

glassy materials, and catalytic materials. The neutron inelastic,

quasi elastic, and magnetic scattering techniques applied provide unique

information, for example, on: phase transformations; interatom bonds;

electronic structure; sublattice magnetization; hydrogen binding, trapping,

and diffusion; and molecular and crystal dynamics. The members of this

task (and the following task) are also responsible for establishing and

maintaining a center of excellence for neutron scattering and radiographic measurements including a computer-controlled network of ten

spectrometers at the reactor. Task scientists couple directly with

other NBS and outside groups who require state-of-the-art neutron measurement methods and expertise in their programs. Examples include long-term

collaborative efforts with in-house guest workers from Army Materials

Command, Naval Research Laboratory, the Naval Surface Weapons Center (NSWC),

and the University of Maryland on materials for improved microwave

transmission and sonar and advanced explosive formulations; cooperative

fundamental research with industrial scientists (Allied Chemical Corporation, Bell Laboratories) on new classes of materials with potential

applications for advanced power transformers, computers, and energy

storage; and research on hydrogen in metals, intercalation compounds,

and prototype phase transformations in solids with other national laboratories (Argonne National Laboratory; Brookhaven National Laboratory;

National Research Council, Canada) and universities (University of

Illinois; University of Pittsburgh; University of Vermont; Cornell

University; University of Antwerp; University of Munich). In addition,

staff scientists are actively engaged with other Divisions and Centers

at NBS in the application of neutron scattering methods for (1) surface

analysis of chemical products and reactions on industrial catalysts,

(2) ultrasensitive microscopic analysis of hydrogen in metals, and

(3) computer simulation of chemical reactions in condensed phases.

Microscopic Properties of Hydrogen in Metals and Molecular Materials

Subtask 1 of 12162

J. M. Rowe, J. J. Rush, R. C. Casella, S. F. Trevino 1

1 Guest Worker, Army Armament Research and Development Command (AARADCOM)

Hydrogen in Metals

As part of its program of unique studies of vibration spectra and atomicscale behavior of hydrogen in metals down to the 0.1 percent level, this

group (in collaboration with guest workers from the University of Munich,

Institut Laue-Langevin, and University of Illinois) has extended research

on hydrogen trapped by impurities to intermetallic systems (TiCr, Pd3 Mn)

and completed an extensive study of H and D isotopes in palladium down

to 0.2 percent H. Previous NBS measurements on hydrogen trapped by

interstitial atomic oxygen and atomic nitrogen in niobium have been

566-11
utilized to propose a trapping mechanism which is decidedly different

from those proposed on the basis of macroscopic measurements. Associated

with these experiments, theoretical work is being carried out to elucidate the role of elastic strain, H-H interactions, and relaxation effects

on the details of the hydrogen vibration spectra and to study the effects

of band formation by low concentrations of H in pure metals. The neutron

spectra for the or and p-phase PdH

x (Dx

) have yielded several highly

interesting results: (1) an anomalous isotope shift is observed for

hydrogen vibrations in the a- (solute) phase which is the same as that

observed for p-PdH(D), which may have an impact on current theoretical

interpretation of the high- temperature (~ 10 K) superconducting transition observed for palladium hydride near stoichiometry; (2) the optical

vibrations of a-PdH

x show no measurable change for x between 0.002 and

0.02, and thus show no evidence of hydrogen clustering in a-palladium

proposed on the basis of earlier neutron work; (3) the neutron spectra

p-phase palladium deuteri de diluted with a small amount (3 percent) of H

provides, for the first time, a direct measurement of anomalous phonon

splitting due to a chemical 1y equivalent light atom defect in a metal.

Other results during the past year include the observation of diffuse

peaks in the diffraction pattern of a-VD0 g> which can be directly

interpreted as "lattice liquid" distribution of deuteriums within the

regular bcc metal structure. In addition, we are currently designing an experiment to test the utilization of these highly sensitive measurement

capabilities to probe hydrogen at embrittlement levels (< 10 ppm) in

iron and steel.

Disordered and Catalytic Materials

We have continued our theoretical and neutron scattering studies on the

microscopic properties and novel phases of prototype solids exhibiting

orientational disorder associated with local strains and anomalous

elastic behavior. A new theory is being developed to explain the absence

of observable optical modes in alkali cyanides, which includes the

effects of asymmetry (electrical and mechanical) of the CN ion and the

interaction of the optical vibrations with the hindered rotational

states of the linear ions. Both experimental and theoretical studies

have continued of the novel "quadrupole glass" state proposed for KCN-KBr

mixed crystals from our previous neutron scattering work. Recent articles

have questioned the existence of a real transition to such a state in

these materials, based on observed dielectric behavior. However, our recent analysis shows conclusively that the alternative explanation of

orientational behavior in these compounds (a gradual "freezing in") is

totally inconsistent with the neutron data and thus very likely an incorrect interpretation of the dielectric results.

Our collaborative research effort with the Surface Science and Molecular

Spectroscopy Division on neutron scattering investigations of chemical

species and reactions on fine-particle metallic catalysts has been

extended to systematic studies of chemisorption on carefully processed

platinum catalysts under relevant temperature and pressure conditions.

Different binding states have been found for hydrogen chemisorbed on "unperturbed" platinum sites compared to sites containing oxygen impurities near the surface. Studies of adsorbed ethylene and acetylene as a function of temperature reveal the creation at temperatures > 150 K of a

566-12
more highly saturated hydrocarbon species, possibly analogous to methylated

species suggested from electron scattering studies on single crystals of

platinum under ultrahigh vacuum conditions. Recently we have also

completed our first studies of the low-frequency (0 to 10 THz) dynamics

of the platinum catalysts with ethylene surface layers, using the new

NBS time-of-'fl ight neutron spectrometer. These studies are being pursued

in an attempt to probe directly the rotational behavior of hydrocarbon

fragments on metal catalysts.

Finally, in cooperative research efforts with Army guest workers and the

Center for Chemical Engineering on computer simulation of chemical

reactions in condensed materials, this group has simulated both the

equilibrium and nonequilibrium behavior as a function of temperature and

the energy transfer mechanisms of model dimers bound in the solid state.

This work is intended to establish a predictive capability for fast

chemical interactions in molecular solids under conditions far from

equilibrium (e.g., in a shock wave).

Microscopic Properties of Magnetic and Amorphous Materials

Subtask 2 of Task 12162

J. J. Rhyne, J. Lynn, 1 H. Alperin, 2R. Erwin, 3 J. Fernandez-Baca3

1 Consul tant , University of Maryland

2 Guest Worker, Naval Surface Weapons Center

3 Guest Worker (Graduate Student), University of Maryland

This subtask provides a focus for application and improvement of neutron

elastic and inelastic scattering techniques for fundamental studies of

the microscopic properties of new classes of metallic and magnetic

materials (including rare earth metal compounds, magnetic hydrides, and

amorphous and spin glass materials), many of which exhibit novel properties

of potential use in device applications and high-technology products.

This research is carried out in close collaboration with industrial

laboratories, universities, and other CMS scientists.

During the past year, research emphasis in the subtask was placed on

(1) spin dynamics of the rare earth Laves phase alloy HoA 1 2 , which

exhibits a strong interplay of exchange and crystal field interaction

energies (collaboration with NRL); (2) dynamics and critical properties

of a class of amorphous metal alloys, which exhibit coexistence pheno- mena of ferromagnetism and spin glass states, and a reentrant spin glass

state at low T (collaboration with Bell Laboratories and the University

of Maryland); (3) expanded studies of Fe

xB^_x amorphous alloy spin

dynamics and local and intermediate range atom-atom correlations, including

additional compositions exhibiting the Invar anomaly and a study of the

unusual temperature renormalization of the spin stiffness found for

these prototype soft magnetic alloys (collaborative research with Allied

Chemical Corporation and NRL); (4) extended measurements of small-angle

magnetic scattering in coexistent superconducting-magnetical ly ordered

compounds below 1.5 K (collaboration with the University of Maryland);

(5) detailed analysis of the atomic structure correlations in rapidly

solidified TbFe2 and YFe2 alloys to examine correlations higher than

pair-pair interactions (collaboration with NRL); and (6) studies of the

566-13
microstructure, short-range order, and tranformations of metallic glasses

and "glassy" carbon as a function of hi gh- temperature annealing [in

cooperation with the Metallurgy Division and the University of California

(Berkeley)].

Highlights during the past year include:

• Established the existence of propagating magnetic modes of highly

anisotropic character in HoA 1 2 and determined the effect of the

large crystal field interaction of the exchange splitting of states

in this compound.

• Confirmed an anomalous T

5/2 power temperature renormalization of

the spin wave stiffness parameter in two amorphous F e

x B^_x compound

compositions and examined the unusual departure of the spin stiffness constant from that calculated from the magnetization.

• Extended results on small-angle magnetic scattering in TbFe2 and

YFe 2 to 0.15 A

-1 and confirmed the absence of a conventional second

order phase transition at T and the existence of microdomain order

below T . c

0 Initiated a study of the effect of composition and heat treatment

on the magnetic structure of amorphous metal alloys and a correlation of the results with changes in their magnetostructure behavior.

0 Established the existence of two time-scales in the magnetic order

of Fe

x

N '> 1

_ x glassy alloys--one related to the statics as manifested

by a resolution-limited elastic scattering peak and a second significantly shorter time-scale associated with the spin excitations.

0 Examined the coexistence of a superconducting and ferromagnetic

state in the compound Er0 #

1

Ho0 . 9 Rh4 B 4 and the magnetic behavior in

the vicinity of the mul ticritical point.

566-14
NEUTRON STRUCTURE METHODS AND CRYSTAL DATABASE FOR MATERIALS UTILIZATION

AND DURABILITY

Task 12163

This task utilizes the unique properties of neutrons (deep penetration

capability, sensitivity to light atoms, and well-defined lineshapes for

precise structure analysis) to extend basic cutting edge measurement

capabilities in the structural analysis and nondestructive testing of

materials. Task members have competences at the forefront of measurement

and analysis of materials structure, including concentrated efforts in

neutron powder diffraction, profile analysis methods, broad expertise in

radiographic measurement technology, and state-of-the-art computercontrolled diffraction facilities. This expertise is used to develop

advanced diffraction and radiographic methods and analytical techniques

to provide: (1) preci se structure analysis essential for effective use

of materials (e.g., in batteries, chemical catalysis); (2) development

and computerized transfer of evaluated materials structure database to

industrial and scientific user community; and (3) nondestructive reference

methods for defects, precipitations, and texture affecting metal product

performance, for improved quality assurance, e.g., in composities,

rapidly solidified alloys, and plant and field inspections and for

microstructure analysis of materials under stress. Current research and

measurement activities include cooperative projects with four CMS Divisions

(Materials Structure and Durability) and the Center for Radiation Research.

This task also directly serves the Offices of Nondestructive Evaluation

and Standard Reference Data. Outside interactions and cooperative

research with groups needing advanced neutron methods include National

Institutes of Health (NIH); Naval Research Laboratory; Army Materials

Command; U.S. Navy Department; Food and Drug Administration; Smithsonian

Institution; Allied Chemical Corporation; Bell Laboratories; E. I. Dupont

de Nemours, Inc.; Metronics, Inc.; Union Carbide Corporation; 3 M Co.;

and universities on projects ranging from crystallographic database

development to the structure of proteins.

Neutron Diffraction Methods and Applications

Subtask 1 of 12163

E. Prince, A. Santoro, B. Mozer, H. Prask, 1 C. Choi, 1 A. Wlodawer,

M. Miller2

1 Guest Worker, AARADCOM

2 Guest Worker, NIH

Recent improvements in refinement methods and lineshape analysis for

powder diffraction developed by this group continue to greatly enhance

research and applications on the structure and microscopic properties of

complex inorganic materials. During the past year, a great deal of work

has been completed on the structure of prototype or tailored oxide

compounds whose novel ionic or electronic conductivity are of interest

in the development of more efficient or smaller batteries or in other

electronic applications. These efforts include determination of the

structure and conduction paths in lithium-based tantalate or vanadate

compounds with scientists from Bell Laboratories, the University of

Grenoble, and the Materials Chemistry Division and studies of the

566-15
composition dependence of conductive channels in sodium supericnic

conductor (NASICON) solid solutions, which are linked three dimensionally

in the structure and provide conductivities at 300 °C comparable to

p-alumina. In addition, a series of investigations have been completed

(with NRL) of the structure of p-phase Pb02 , both chemically produced

and extracted from lead storage batteries after varying degrees of

electrolysis. These studies are aimed (along with chemical tests) at

providing detailed information on the factors (including impurity phases),

which influence battery lifetime and performance. Among other applications,

diffraction techniques have been used to determine the structure of

copper complexes of the corrosion- inhibitor benzotriazolate in cooperation

with 3M Research Laboratory, to study the hydrogen bonds in complex

phosphates with the Polymer Division's dental research group, to determine cancer drug structures with the American Dental Association, and in a preliminary study, in collaboration with E. I. Dupont de Nemours, Inc.,

of structure and cage geometry in zeolyte catalysts.

In the past year, neutron diffraction methods have also been used in

several metallurgical and NDE applications. In cooperation with the

Polymer and Metallurgy Divisions, we have initiated a study of the

effects of interstitial elements on phase relationships in Ti-Al alloys,

which will ultimately be carried to 1500 K. In addition, we have demonstrated with the Naval Surface Weapon Center the feasibility of using

neutron diffraction as a tool for studies of the effects of compressive

stress on the separate components in a composite material (SiC-Al).

In our long-term collaborative program with Army guest workers on the

structure and properties of metastable materials this subtask has

(1) completed a series of x-ray line profile analyses of structural

differences in cellulose produced from cotton linter and less costly

wood pulp. This is part of an effort to identify critical feedstock

properties for quality control which would allow production of cellulose

compounds from more readily available wood pulp sources; and (2) determined

the structure of the low temperature phase of ammonium nitrate to complete

a long-term study of all of the phases of this compound.

Finally, in the NBS-NIH collaborative project on the structure of biological materials, our group has completed collection of neutron and x-ray

data on ribonuclease enzyme doped with a vanadium complex to simulate

the conditions which exist on a molecular scale during biocatalysis

involving this enzyme. A study has also been initiated in collaboration

with the University of Peking of the structure of insulin (to obtain

detailed information on the roles of H bonds in the structure).

NBS Crystal Data Center

Subtask 2 of 12163

A. D. Mighell, J. K. Stalick, V. L. Himes 1

X NBS Coop Student from Catholic University

The Crystal Data Center collects, evaluates, and disseminates to the

industrial and scientific community crystal lochemi cal data that are required for the identification and characterization of solid-state

materials. The work of the Center is carried out in close collaboration

566-16
with allied data centers in the United States, England, Canada, and the

Federal Republic of Germany. A major recent objective is to build a computer-based Master Data File around which all operations are based.

Accomplishments during the past year include:

• The establishment of a formal agreement with the International

Centre for Diffraction Data and the Joint Committee on Powder

Diffraction to expedite collection of crystal data and the marketing

of the Crystal Data Identification file to the chemical and materials

community via magnetic tape.

• Approximately 2000 entries with metals and intermetal lie data have

been added to the Master Database and an on-line search system for

the Crystal Data File was implemented by the Chemical Information

System. In addition, format specifications for Volumes 5 and 6 of

Crystal Data were completed.

• In our research efforts on crystallographic analysis and evaluation,

a new matrix method for critical evaluation of symmetry was designed

and tested and a program for calculation of densities from atomic

volumes was incorporated into the data system.

Radiographic Methods and Standards

Subtask 3 of Task 12163

D. A. Garrett, M. Ganoczy, and Y. T. Cheng 1

1 Guest Worker, Smithsonian Institution

Due to staff reduction and extensive illness within the group, the

activities of this subtask were somewhat curtailed. Significant progress,

however, was made towards the development of neutron autoradiographic

methods. In particular, the joint program with the Smithsonian Institution

in the autoradiography of paintings continued to develop. The design of

a major facility to be installed at the thermal column has been completed.

A preliminary experimental setup was used to obtain autoradiographs of a sixteenth century Russian icon and a nineteenth century painting by

Dewing, a well-known American artist. These series of autoradiographs

demonstrated the value of this method in the study of valuable paintings.

Neutron autoradiography provides a nondestructive means to analyze

chemical composition of pigments in place, and thus for example help in

validation of original art works, and locates overpainting by the artist.

A variety of other tasks was completed. Preliminary work in cooperation

with the Naval Research Laboratory was undertaken to explore the possibility of obtaining tomographic-type information from a series of radiographs

taken as the object was rotated. Several feasibility studies were made

including:

• Identification of loose plastic material in gyroscopes

566-17
• Determination of oil levels in accumulators used in missiles

• Search for hidden cracks in turbine blades

• Void density in composite binding material

In addition, film exposure curves were determined for a standard neutron

beam conditions and a variety of converter screens.
ADVANCED NEUTRON METHODS

Task 51102

C. J. Glinka, N. Berk, J. LaRock, J. M. Rowe, 1 S. Singhal 2

Competence Leader from Task 12162

2 IPA Fellow

This task is one of the NBS competence building initiatives whose objective

is to develop and maintain state-of-the-art facilities for advanced

neutron scattering techniques and contribute to effective application of

these facilities and techniques in solid-state physics, metallurgy,

polymer science, and biology. The original focus of this initiative is on providing new major facilities for SANS and high-resolution, low-wave

vector, inelastic scattering. With small -angle neutron scattering, one

can probe structural entities and defects and inhomogenieties on the

o 10 to 3000 A scale, while high-resolution, inelastic studies allow the

observation of dynamic phenomena with characteristic times as low as

O 10-10 s and spatial regions of 1 to 100 A. The new facilities (which

provide a world-class capability for NBS in these areas) will serve a wide variety of materials science and measurement programs within NBS,

including polymer and surface science, materials microstructure and

durability, nondestructive testing, and properties of fluids and solutions.

New science and applications to be developed range from unique studies

of the structure of polymers, high-technology magnetic glasses, and

catalysts to the precise measurement of bulk microstructure in industrial

materials and products under environments experienced in production and

service. Close cooperation with a number of divisions within CMS and

the Center for Chemical Physics (CCP) is an essential part of the Advanced

Neutron Method Task, as is wide-ranging cooperative research and measure- ment activities with other Government laboratories and with a number of

industries and universities.

Summary of Activities

Faci 1 ities

During the past year, the 64 x 64 detector has been installed in the SANS

facility and is now fully operational. The operating characteristics of

the SANS instrument are now well-established, and the results are generally

in accord with the original calculations, i.e., a neutron flux at the

sample of from 104 to 3 x 10 s n/cm2 /s under the highest and lowest resolution conditions respectively. These numbers will double when the reactor

power increases to 20 MW next year. In addition, we have installed an automatic sample changer (computer-controlled), which can cycle up to four

samples into the beam while the system is evacuated, and computer-controlled

cryogenic and furnace sample environmental chambers. These enhancements

have greatly increased the efficiency of utilization of the facility. We

have also adapted horizontal and vertical field electromagnets to provide

up to 10 kilogauss fields at the sample position. Data analysis and display

programs have been developed to allow rapid assessment of data as it is

taken, utilizing an interactive color graphics imaging system which allows

easy visual assessment of the data. This capability is unique to the NBS

566-19
SANS facility. The neutron time-of-f 1 ight facility also became operational

during the past year, and the signal-to-noise ratio has been increased

significantly to the point that even difficult experiments are now possible. The data acquisition hardware and software are fully operational, and several experiments have been completed. Further planned

upgrading to this facility includes new shielding, an evacuated flight

path, additional detectors, better sample environmental facilities, and

improved incident energy resolution. These improvements, combined with

the reactor power increase to 20 MW, will make this a world-class facility.

Research and Measurement

The new state-of-the-art measurement capabilities associated with this

Task have stimulated a number of exciting research efforts during the

past year, particularly in the areas of polymers, metallurgy and ceramics,

NDE, and in the physics of novel magnetic and glassy materials. A great

deal of effort has been concentrated on establishing strong interactive

research with other CMS Divisions (Polymers, Fracture and Deformation,

Metallurgy) and with CCP, but our SANS and high-resolution inelastic

scattering facilities have also been heavily utilized in cooperative

research with outside industrial laboratories and universities, including

Union Carbide Corporation; Exxon Chemical Company; Allied Chemical

Corporation; Bell Laboratories; University of Wisconsin; University of

Illinois; Northwestern University; State University of New York, SUNY;

University of Maryland; and Institut Laure-Langevin, Grenoble, France,

and with Government laboratories (NSWC, NRL, NIH).

Among accomplishments and initiated research and measurement efforts

during the past year are:

• The first direct observation of size and density distributions of

O microcracks (< 1000 A) in bulk ceramics by SANS (Fracture and

Deformation and Reactor Radiation Divisions).

• Measurement of the interaction of polymers and surfactants in

solution (Polymer and Reactor Radiation Divisions and Union Carbide

Corporation).

• Nondestructive evaluation of distributed damage and creep- induced

cavitation related to component failure in stainless steel products

(Reactor Radiation and Fracture and Deformation Divisions).

• Studies of magnetic microstructure and voids in maraging steel

(Fracture and Deformation and Reactor Radiation Divisions).

• Investigation of magnetic and superconducting transitions in pseudoternary alloys and of magnetic clustering in amorphous TbFe2 (Reactor

Radiation Division and University of Maryland).

• Completed initial measurements of low-energy spectra measured for

hydrocarbon species trapped on the surface of metallic catalysts

(Reactor Radiation Division and Center for Chemical Physics).

566-20
• Initiated systematic study of short-range order and transformations

in TiCu metallic glasses (Reactor Radiation and Metallurgy Divisions

with Allied Chemical Corporation).

§ Initiated SANS study of spi nodal decomposition in FeCr alloys (with

Northwestern University).

Finally, a great deal of research on polymer chains and block copolymers

in the solid state and in solution has been carried out by the Polymer

Division in cooperation with scientists from the University of Wisconsin,

University of Massachusetts, and with a number of Japanese guest workers.

566-21

Other Activities of the

Reactor Radiation Division

Invited Talks

Studies of Ribonuclease A by X-ray and Neutron Diffraction

Chalmers Institute of Technology, Gothenburg, Sweden

A. Wlodawer

November 3, 1981

Neutron Scattering Studies of Hydrogen in and on Metals

Physics Department, Cornell University, Ithaca, NY

J. J. Rush

December 2, 1981

Neutron Spectroscopic Studies of Dilute Hydrogen in Pure and Defected

Metal

International Symposium on the Electronic Structures and Properties

of Hydrogen in Metals, Richmond, VA

J. J. Rush

March 5, 1982

A Procedure for Joint Refinement of Macromolecular Structures with

X-ray and Neutron Single Crystal Diffraction Data

American Crystallographic Association Spring Meeting, National Bureau

of Standards, Gaithersburg, MD

A. Wlodawer

March 31, 1982

The Structure of the Enzyme-Active Substrate Complex in Ribonuclease

7th European Crystallography Meeting, Jerusalem, Israel

A. Wlodawer

April 29, 1982

Translation-Rotation Coupling-Mixed Crystals of KCN

x KBr^_x National Bureau of Standards, Surface Science Division,

Gaithersburg, MD

J. M. Rowe

April 1982

New Developments of the Rietveld Method. Applications to the Study

of the Structure of Pb0 2 in Lead-Acid Batteries

Institute of Chemistry, Polytechnic of Milano, Milano, Italy

A. Santoro

May 28, 1982

Joint X-ray and Neutron Refinement of Proteins

Neutron Scattering Analysis for Biological Structure--Brookhaven

Symposia, Upton, NY

A. Wlodawer

June 3, 1982

566-23
New Developments of the Rietveld Method of Structural Refinement.

Applications to the Study of Ionic Conductors

University of Messina, Messina, Italy

A. Santoro

June 15, 1982

New Developments of the Rietveld Method of Structural Refinement.

Applications to the Study of Ionic Conductors

National Commission of Nuclear Energy, Rome, Italy

A. Santoro

June 27, 1982

Neutron Scattering Study of Magnetic Ordering in Ternary Superconductors

Meeting on d- and f-Band Metals, Julich, Federal Republic of Germany

J. W. Lynn

June 1982

Assessing the Fit

Powder Diffraction and Rietveld Analysis Workshop, Argonne National

Laboratory, Argonne, IL

E. Prince

July 14, 1982

Non-linear Least Squares Fundamentals

Powder Diffraction and Rietveld Analysis Workshop, Argonne National

Laboratory, Argonne, IL

E. Prince

July 14, 1982

Constrained Refinement and Model Building

Powder Diffraction and Rietveld Analysis Workshop, Argonne National

Laboratory, Argonne, IL

E. Prince

July 15, 1982

High Resolution Neutron Diffraction of Proteins

Gordon Conference on "Diffraction Methods in Molecular Biology,"

Proctor Academy, Andover, NH

A. Wlodawer

July 30, 1982

Division Seminars

Transport in Amorphous Metals

S. R. Nagle

University of Chicago, Chicago, IL

October 26, 1981

Computer Molecular Dynamics

S. Yap

MIT, Cambridge, MA

November 6, 1981

566-24
Experience with Time-of-Flight Neutron Powder Diffraction at IPNS

T. M. Sabine

New South Wales Institute of Technology, Sidney, Australia

December 21, 1981

Gamma Ray Scattering: Applications in Condensed Matter Science

William Yelon

University of Missouri, Columbia, MO

February 2, 1982

Diffusion in Concentrated Lattice Gases

K. Kehr

Institut fur Festkorperforschung der Kernforschungsanlage Julich,

Julich, Federal Republic of Germany

March 6, 1982

Temperature Dependence of the Structure Factor of As 2 Se3 up to the

Glass Transition

L. E. Bussee

University of Chicago, Chicago, IL

March 23, 1982

Quadrupolar Interactions and Structural Instabilities in PrAg Cu,

J. A. Gotaas

x x University of Illinois at Chicago Circle, Chicago, IL

March 26, 1982

Magnetic Properties and Applications of Amorphous Metallic Glasses

R. Hasegawa

Allied Corporation, Morristown, NJ

April 21, 1982

Hydration in Aqueous Solutions

Stewart Cummings

Institut Laue-Langevin, Grenoble, France

June 16, 1982

Technical and Professional Committee Participation and Leadership

American Crystallographic Association

Apparatus and Standards Committee, E. Prince, Chairman

Crystallographic Computing and Data Committee, A. Mighell, Liaison

Officer

Spring Meeting, Mathematics of Refinement Session, E. Prince,

Session Chairman

American National Standards Committee

N-17: Research Reactors, Reactor Physics, and Radiation Shielding,

R. S. Carter, Chairman, T. M. Raby, Secretary

American Nuclear Society

ANS-15 Standards for Research Reactors, T. M. Raby

Standards Steering Committee, R. S. Carter, Voting Member

566-25
American Physical Society, Solid State Meeting (March)

Amorphous Magnets Session, J. J. Rhyne, Session Chairman

American Society for Nondestructive Testing

Penetrating Radiation Committee, D. A. Garrett, Voting Member

Personnel Qualifications Committee, D. A. Garrett, Voting Member

American Society for Testing and Materials

E-7.05: Nondestructive Testi ng--Neutron Radiography, D. A. Garrett,

Secretary

Argonne National Laboratory

Program Review Committee for the Intense Pulsed Neutron Source,

J. M. Rowe, Chairman

Department of Energy

Panel to Review U.S. Pulsed Neutron Scattering Research Facilities,

J. J. Rush, Member

Peer Review Panel for the Assessment of the Program in Basic Energy

Sciences, J. M. Rowe, Member

Gordon Conference on Orientational Disorder in Crystals (1982)

Reorientation Phenomena in Crystals Session, J. M. Rowe, Discussion

Leader

Gordon Conference on Orientational Disorder in Crystals (1984)

J. M. Rowe, Vice-Chairman

International Centre for Diffraction Data

Data Base Subcommittee, A. D. Mighell, Member, J. K. Stalick,

Member

International Conference on Magnetism (1985)

Executive Committee, J. J. Rhyne, Publications Chairman

International Symposium on the Electronic Structure and Properties of

Hydrogen in Metals

International Organizing Committee, J. M. Rowe, Member

Session VI, J. M. Rowe, Session Chairman

International Union of Crystallography

Data Commission, A. D. Mighell, Member

International Union of Crystallography/National Bureau of Standards

Crystal Data Management Board, A. D. Mighell, Member

National Academy of Sciences

Panel on Synchrotron Radiation Facilities, J. M. Rowe, Member

National Bureau of Standards

Library Committee, R. C. Casella, Subject Specialist

National Institute of General Medical Sciences

Ad-hoc Study Section, A. Wlodawer, Member

566-26
Oak Ridge National Laboratory

National Center for Small Angle Scattering Program Committee,

B. Mozer, Member, J. J. Rhyne, Member

Neutron Scattering User Program Advisory Committee, J. J. Rush,

Member

Rare Earth Research Conferences

Proceedings, J. J. Rhyne, Co-editor

27th Annual Conference on Magnetism and Magnetic Materials

Amorphous Alloys III: Rare Earths Session, J. J. Rhyne, Session

Chai rman

Publ i cations

Brun, T. 0.; Susman, S. ; Rowe, J. M. ; Rush, J. J. Quasielastic

neutron scattering study of ionic diffusion in p-LiAl. Solid State

Ionics 5: 417; 1981.

Casella, R. C. Detection of impurity tunneling in solids via coherent

phonon coupling and direct neutron scattering. J. Phys. C 42: 923;

1981.

Cava, R. J. ; Himes, V. L. ; Mihell, A. D. ; Roth, R. S. FeNb 3 Se 10 : a new structure type related to NbSe3

. Phys. Rev. B 24: 3634; 1981.

Chen, H. S. ; Lynn, J. W. ; Erwin, R. W. ; Rhyne, J. J. Spin wave

excitations in re-entry para-fero-spi n glass transition in glassy ^e x^

1"l-x^75^16^6^^3 9^ asses * Proceedings of the 4th international conference on rapidly quenched metals, 1981. Sendai, Japan.

Plenum Press, p. 1153.

Himes, V. L. ; Mi ghe 11, A. D. ; DeCamp W. H. Structure of carbamazepi ne 5H-Dibenz[b,f]azepine-5-carboxamide, Acta Crystal logr. Sect. B 37:

2242; 1981.

Himes, V. L. ; Mi ghe 1 1 , A. D. ; Page, S. W. ; Stack, M. E. Structure of

xanthomegnin, Acta Crystal logr. Sect. B 37: 1932; 1981.

Himes, V. L. ; Mighell, A. D. ; Siedle, A. R. Synthesis and structure

of Cu 5 (BTA) 6 (t-C 4 H 9 NC) 4 , a mixed-valent copper-nitrogen cluster

containing n 3_ benzotriazolate, J. Am. Chem. Soc. 103: 211; 1981.

Prince, E. Comparison of profile and integrated intensity methods in

powder refinement. J. Appl . Crystal logr. 14: 157; 1981.

Rosenthal, J; Yarmus, L. ; Berk, N. F. Comments on tripl et-exci ton

annihilation and triplet spin relaxation in molecular crystals.

Phys. Rev. B 24: 1103; 1981.

Rush, J. J. ; Magerl , A.; Rowe, J. M. ; Harris, J. M. ; Provo, J. L. Tritium vibrations in niobium by neutron spectroscopy. Phys. Rev.

B 24: 4903; 1981.

566-27
Sjolin, Lennart; Wlodawer, Alexander. Improved technique for peak

integration for crystallographic data collected with positionsensitive detectors: a dynamic mask procedure. Acta Crystal logr.

Sect. A 37: 594; 1981.

Tsai, D. H. ; Trevino, S. F. Thermal relaxation in a dense liquid

under shock compression. Phys. Rev. A 24: 2743; 1981.

Alefeld, B. ; Anderson, D. S. ; Heidemann, A.; Margerl , A.; Trevino, S. F. The measurement of tunnel states in solid CH 3 N0 2 and CD 3 N0 2

. J. Chem.

Phys. (Lett, to the Editor) 76: 2758; 1982.

Casella, R. C. Relations between fermion masses from effective potentials in internal space. II Nuovo Aimento 67A: 289; 1982.

Cava, R. J. ; Santoro, A.; Murphy, D. W. ; Roth, R. S. ; Zahurak, S. The

structures of lithium-inserted metal-oxides: LiRe03 and Li 2 Re0 3

. J. Solid State Chem. 42: 251; 1982.

Clausen, K. ; Rhyne, J. J. ; Lebech, B. ; Koon, N. C. Temperature dependence of the spin-waves in ErFe 2

. J. Phys. C 15: 3587; 1982.

Doherty, R. M. ; Stewart, J. M. ; Mighell, A. D. ; Hubbard, C. R.

;

Fatiadi, A. J. The structure of the 1:1 molecular complex of pyrene

and dicyanomethyl enecroconate. Acta Crystallogr. Sect. B 38: 859; 1982.

Ferrick, J. H. ; Rhyne, J. J. ; Segnan, R. Bulk magnetization of

dysprosium-scandium alloys, J. Appl. Phys. 53: 2232; 1982.

Hardman, K. ; Rhyne, J. ; Malik, S. ; Wallace, W. E. Site magnetization

of cubic and hexagonal HoMn2

. J. Appl. Phys. 53: 1944; 1982.

Hardman, K. ; Rhyne, J. J. ; Prince, E. ; Smith, H. K. ; Malik, S. K.

;

Wall are, W. E. Magnetic and structural properties of ThgMn

23

D x and

YgMn

23

D x

, Chapter in The rare earths in modern science and technology,

Vol. III. McCarthy, G. ; Silber, H. ; Rhyne, J. , eds. New York, NY:

Plenum Press; 1982. p. 477.

Himes, V. L. ; Mighell, A. D. ; Stalick, J. L. ; Zon, G. Structure of

racemic cis-4-phenylcyclophosphamide. Acta Crystallogr. Sect. B 38:

1009; 1982.

Lynn, J. W. ; Rhyne, J. J. ; Budnick, J. I. Observation of spin-waves

in Pd (1.5% Fe). J. Appl. Phys. 53: 1982; 1982.

NBS crystal data identification file. Mighell, A. D. ; Stalick, J. K.

,

eds. JCPDS-ICDD Data Tape; 1982. (A data tape which is being distributed for the NBS Crystal Data Center).

NBS crystal data identification file. Mighell, A. D. ; Stalick, J. K.

,

eds. (On-line version of the Ident. File, component database of the

NIH/EPA Chemical Information System) 1982.

566-28
Prince, E. Comparison of the fits of two models to the same data set.

Acta Crystal logr. Sect. B 38: 1099; 1982.

Rhyne, J. J. ; Fish, G. E. ; Lynn, J. W. Spin waves in amorphous

Fe

1

_ x

Bx alloys. J. Appl. Phys. 53: 2316; 1982.

Rhyne, J. ; Hardman, K. ; Malik, S. ; Wallace, W. Magnetic properties

of cubic and hexagonal HoMn2. J. Appl. Phys. 53: 1944; 1982.

Santoro, A.; Roth, R. S. ; Austin, M. Powder neutron diffraction study

of the nonstoichiometric solid solution of lithium tantalate

9LiTa03 :Ta2 0 5. Acta Crystal logr. Sect. B 38: 1093; 1982.

Thomlinson, W. ; Shirane, G. ; Lynn, J. W. ; Moncton, D. Neutron scattering study of magnetic ordering in ternary superconductors, Chapter in

Superconductivity in ternary compounds. Fischer, 0.; Maple, N. B. , eds.

Topics in Current Physics Series, Vol. 2. New York, NY: Springer-Verlag;

1982

Wlodawer, Alexander; Bott, Richard; Sjolin, Lennart. The refined

o crystal structure of ribonuclease a at 2.0 A resolution. J. Biol.

Chem. 257: 1325; 1982.

Wlodawer, Alexander; Hendrickson, Wayne A. A procedure for joint refinement of macromolecular structures with x-ray and neutron diffraction

data from single crystals. Acta Crystallogr. Sect. A 38: 239; 1982.

Wlodawer, Alexander; Sjolin, Lennart. Hydrogen exchange in rnase a: neutron diffraction study. Proc. Natl. Acad. Sci. USA. 79: 1418; 1982.

Wlodawer, Alexander; Sjolin, Lennart; Santoro. A. Refinement of the

crystal orientation matrix for the flat-cone diffractometer. J. Appl.

Crystallogr. 15: 79; 1982.

Ammon, H. L. ; Murphy, K. C. ; Sjolin, L. ; Wlodawer, A.; Holcenberg, J. S. Roberts, J. The molecular symmetry of gl uatminase-asparaginases rotation

function studies of the Pseudomonas 7A and Aci netobacter Enzymes . Acta

Crystallogr.; in press.

Berk, N. F. ; Rosenthal, J; Yarmus, L. Spin relaxation of triplet

excitons in molecular crystals. Phys. Rev. B; in press.

Cavanagh, R. ; Kelley, R. D. ; Rush, J. J. Neutron vibrational spectroscopy of hydrogen and deuterium on raney nickel. J. Chem. Phys.;

in press.

Choi, C. S. ; Mighell, A. D. Neutron diffraction study of sodium

sesqui carbonate dihydrate. Acta Crystallogr.; in press.

Choi, C. S. ; Prask, H. J. Single crystal neutron diffraction study

of ammonium nitrate phase III. Acta Crystallogr.; in press.

Cohen, Jack S. ; Wlodawer, Alexander. Diffraction and NMR studies of

proteins; an uneasy alliance. Trans. Biochem. Sci.; in press.

566-29
D'Antonio, Peter; Konnert, John H. ; Rhyne, James J. ; Hubbard, Camden R. Structural ordering in amorphous TbFe2 and YFe2

. J. Appl. Crystal logr.

;

in press.

Glinka, C. J. The National Bureau of Standards small-angle neutron

scattering spectrometer. Proceedings of the conference on neutron

scattering; 1981. Argonne, I L ; in press.

Glinka, C. J. ; Berk, N. F. The two dimensional position-sensitive

detector at the National Bureau of Standards SANS facility. Proceedings

of the workshop on position-sensitive detectors; 1982; Grenoble, France,

in press.

Himes, V. L. ; Mighell, A. D. A matrix method for lattice symmetry

determination. Acta Crystal logr. Sect. A; in press.

Hodeau, J. L. ; Marezio, M. ; Santoro, A.; Roth, R. S. Neutron profile

refinement of the structures of Li 2 Sn0 3 and Li 2 Zr0 3

. J. Solid State

Chem. ; i n press.

Lynn, J. W. ; Erwin, R. W. ; Chen, H. S. ; Rhyne, J. J. Evolution from

ferromagnetism to spin-glass behavior. Phys. Rev. Lett.; in press.

Lynn, J. W. ; Erwin, R. W. ; Rhyne, J. J. ; Chen, H. S. Ferromagnetic

and spin glass behavior near the critical concentration in amorphous

(Fe

xNi^_x )^^G

2

^. J. Mag. Matls.; in press.

Lynn, J. W. ; Shelton, R. N. ; Hornig, H. E. ; Glinka, C. J. Investigation

of the magnetic and superconducting properties of Er, Ho Rh.B..

Physica (Utrecht) B; in press.

x

Magerl , A.; Rowe, J. M. ; Rush, J. J. ; Wipf, H. ; Richter, D. Influence

of impurities on local hydrogen vibrations in a niobium host lattice.

Proceedings of the international symposium on the electronic structure

and properties of hydrogen in metals; 1982. Richmond, VA. ; in press.

Magerl, A.; Rush, J. J. ; Rowe, J. M. ; Richter, D. ; Wipf, H. Local

hydrogen vibrations in Nb in the presence of interstitial (N,0) and

substitutional (V) impurities. Phys. Rev. B; in press.

Nicholson, W. L. ; Prince, E. ; Buchanan, J. ; Tucker, P. A robust/

resistant technique for crystal structure refinement, chapter in

Progress and problems in crystallographic statistics. Wilson, A. J. C.

,

ed. International Union of Crystallography; in press.

Prask, H. J. ; Choi, C. S. Texture, NDE characterization 420/00089,

chapter in Encyclopedia of materials science and engineering, in press.

Prince, E. ; Nicholson, W. L. A test of a robust/resistant refinement

procedure on synthetic data sets. Acta Crystal logr. Sect. A; in press.

Rowe, J. M. ; Rush, J. J. ; Michel, K. H. Comment on dielectric susceptibility measurements in (KCN) (KBr), mixed crystals. Phys. Rev. Lett.;

in press.

x i

" x

566-30
Santoro, A. New developments in neutron powder profile analysis.

Proceedings of the Italian-Yugosl avian joint meeting. 1982; Bled,

Yugoslavia; in press.

Santoro, A.; Cava, R. J. ; Murphy, D. W. ; Roth, R. S. Use of the Pearson

type VII distribution in the neutron profile refinement of the structures of LiRe03 and Li 2 Re0 3

. Proceedings of the symposium on neutron

scattering; 1981. Argonne, IL. American Institute of Physics; in press.

Susman, S. ; Delbecq, C. J. ; Brun, T. 0.; Prince, E. Structure and

conductivity of the NASICON analog Na3 Sc2 (P0 4 ) 3

. Proceedings of the

symposium on solid electrolytes. 1982; Montreal, Canada; in press.

Wlodawer, Alexander. Neutron diffraction of crystalline proteins,

chapter in Progress in biophysics and molecular biology. Blundell, T.

ed. Oxford, England: Pergamon Press Ltd. ; in press.

Wlodawer, Alexander. A facility for data collection and processing

at the National Bureau of Standards reactor. Chapter in Methods in

enzymology. Wyckoff, H. W. ; Hirs, C. H. W. ; Timasheff, S. N. , eds.

New York, NY: Academic Press; in press.

Wlodawer, Alexander; Sjolin, Lennart. Application of joint neutron

and x-ray refinement to the investigation of the structure of

o ribonuclease a at 2.0 A resolution. Brookhaven symposia in biology.

Upton, NY: Plenum Press; 1982; in press.

Wlodawer, Alexander; Sjolin, Lennart. Improvement of the quality of

the data collected using a position-sensitive detector. Nucl

Instrum. Methods; in press.

Special Reports

Prask, H. J. ; Choi, C. S. The correlation of nitrocellulose

properties and cellulose feedstock crystal structure. ARRA0C0M

Tech. Report; 1982.

Rush, J. J. Report of the pulsed neutron research review committee.

J. J. Rush, co-author. 1982.

Books

Prince, E. Mathematical techniques in crystallography and materials

science. New York, NY: Springer-Verlag; 1982. 192 pp.

Sponsored Conferences

American Crystallographic Association Winter Meeting

J. K. Stalick, Local Chairman

National Bureau of Standards, Gaithersburg, MD

March 29, 1982- April 2, 1982

566-31
Workshop on the Future of Low Temperature Neutron Radiation

J. J. Rush (co-sponsored with the Department of Energy)

National Bureau of Standards, Gaithersburg, MD

May 19-21, 1982

Consulting and Advisory Services

Argonne National Laboratory

J. M. Rowe, Consultant

Industrial Interactions

Other Industrial Guest Workers at CMS

Allied Chemical Corporation, Gordon E. Fish/J. J. Rhyne

Microscopic properties of spin glasses ana high-technology

magnetic materials

Allied Chemical Corporation, Arnulf J. Maeland/J. J. Rush,

A. Santoro

Structure and dynamics of hydrogen storage materials and

metallic glasses

Bell Laboratories, R. Cava/A. Santoro, R. Roth

Structure and ion transport mechanisms of tailored electronic

ceramics

B-K Dynamics, N. J. Chesser/J. J. Rush

Development of computer software for data analysis

E. I. Dupont de Nemours, Inc., J. B. Parise/E. Prince

Catalytic and adsorbant sites in zeolytes

Exxon Chemical Company, D. J. Lohse/J. J. Rush, C. Han

Compatibility of polyethylene-polypropylene co-polymers

Medtronic, Inc., P. M. Skarstad/J. J. Rush, E. Prince

Microscopic properties of new materials for pacemaker

batteri es

Union Carbide Corporation, P. S. Leung/J. J. Rush, C. Han

Polymer-surfactant interactions in solution

Archival Technical Papers Coauthored With Industrial Employee

FeNb3 Se 10 : A New Structure Type Related to NbSe 3

. Phys. Rev.

B 24: 3634; 1981/V. L. Himes, A. D. Mighell, R. S. Roth, and

R. J. Cava, Bell Laboratories

566-32
Spin Wave Excitations in Re-Entry Para-Fero-Spin Glass Transition

in Glassy (Fe^Ni

i_ x )^,-P^gBgAl

3

Glasses/J. W. Lynn, R. W. Erwin,

J. J. Rhyne and

H. S. Chen, Bell Laboratories

Proceedings of the 4th international conference on rapidly

quenched metals. 1981. p. 1153.

Synthesis and Structure of Cu 5 (BTA) 6 (t-C 4 H 9 NC) 4 , a Mixed-Valent

Copper-Nitrogen Cluster Containing n

3 _ Benzotriazol ate/V. L. Himes,

A. D. Mighell and

A. R. Siedle, 3 M Company

J. Am. Chem. Soc. 103: 211; 1981.

Spin Waves in Amorphous F e

]__ x

B x Alloys/J. J. Rhyne, J. W. Lynn and

G. E. Fish, Allied Chemical Corporation

J. Appl . Phys. 53: 2316; 1982.

The Structures of Lithium-Inserted Metal-Oxides: LiRe0 3 and

Li 2 Re0 3 /A. Santoro, R. S. Roth, and

R. J. Cava, D. W. Murphy, Bell Laboratories

J. Solid State Chem. 42: 251; 1982.

Evolution from Ferromagnetism to Spin-Glass Behavior/J. W. Lynn,

R. W. Erwin, J. J. Rhyne, and

H. S. Chen, Bell Laboratories

Phys. Rev. Lett, (in press)

Ferromagnetic and Spin Glass Behavior Near the Critical Concentration in Amorphous (Fe Ni, ) 7 C.G ?C./J. W. Lynn, R. W. Erwin,

J. J. Rhyne, and

H. S. Chen, Bell Laboratories

J. Mag. Matls. (in press)

Use of the Pearson Type VII Distribution in the Neutron Profile

Refinement of the Structures of LiRe0 3 and Li 2 Re0 3 /A. Santoro,

R. S. Roth, and

R. J. Cava, D. W. Murphy, Bell Laboratories

Proceedings of the Symposium on Neutron Scattering (in press)

Other Cooperative Research and Measurement

Raytheon Company, radiographic inspection of oil levels in

missile accumulation

Gulf Research and Development Company, residual stress in

quartzite by neutron diffraction

Timex Corporation, radiographic examination of gyroscopes

Martin Marietta, Inc., search for voids in composite binders by

neutron radiography

566-33
Data Programs

NBS Crystal Data Center interacts directly with industrial users materials data needs as a component database of the Chemical

Information System and recently concluded a formal agreement with

the International Centre for Diffraction Data, which will expedite

marketing of crystal data file to the industrial community via

magnetic tape.

566-34
—

U.S.

DEPARTMENT

OF

COMMERCE

National

Bureau

of

Standards

A-l

L
A-2
560 CENTER FOR MATERIALS SCIENCE

August 30, 1982

A.
NBS-114A (rev. 2-eo) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO. NBSIR 82-2609

2. Performing Organ. Report NoJ 3. Publication Date November 1982

4. TITLE AND SUBTITLE

Center for Materials Science

Annual Report 1982

5. AUTHOR(S)

6 . PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

7 . Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE S. Type of Report & Period Covered WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bliography or literature survey, mention it here) The Center for Materials Science is part of the National Measurement Laboratory,

one of tne three major units of the National Bureau of Standards. Research

programs in the Center's five technical divisions cover the major classes of

materials (metals, polymers, ceramics, glass and composites) and address basic

needs for materials measurements, standards, and data. The Center provides

generic technical support for optimum efficiency in processing, fabrication,

and utilization of materials. Programs output is disseminated to a wide range

of industrial users and university researchers by means of workshops, industrial

guest worker interactions, formal and informal laboratory and planning visits.

Center staff standards committee activities, technical publications, and

seminar programs. Two key outputs are standard reference materials for

measurement calibration and evaluated standard reference data. The Center

undertakes materials research in NBS mission areas of support measurements and

standards needs of other Federal agencies.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Center for Materials Science; materials; materials performance; materials processing

materials properties, microcharacterization and research

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