NATIONAL INSTITUTE OF STANDARDS &

TECHNOLOGY

Research Information Center

Gaithersburg, MD 20890



Or STANDARDS

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SEP i 6 1981

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TECHNICAL ACTIVITIES 1980 no. go-., fo S CENTER FOR MATERIALS SCIENCE

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John B. Wachtman, Jr., Director

Darrell H. Reneker, Deputy Director

Center for Materials Science

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

October 1 980

Prepared for: National Bureau of Standards

Department of Commerce

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Jordan J. Baruch. Assistant Secretary for Productivity, Technoiogy, and Innovation

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

ABSTRACT

The Center for Materials Science is part of the National Measurement

Laboratory, one of the two principal laboratories comprising the National

Bureau of Standards. The Center is organized in six Divisions, each having

responsibility in different areas of materials science appropriate to the

major classes of materials—metals, polymers, and ceramics and glass.

These Divisions vary in their balance between theory and experiment,

between direct standards work and research, and in their orientation

toward industrial and Government needs and the needs of other components

of the scientific and technical community. This volume summarizes the

technical research activities and accomplishments of the six Divisions

of the Center for Materials Science for fiscal year 1980.

TABLE OF CONTENTS

Page

I. INTRODUCTION 1

II. TECHNICAL ACTIVITIES

CENTER FOR MATERIALS SCIENCE

John B. Wachtman, Jr., Director . 5

Measurement Services 6

Signal Processing and Imaging 6

Fracture Theory 7

Theoretical Materials Stability 8

Processes Involving Conformational Changes

in Polymers 9

Other Center Activities 11

CHEMICAL STABILITY AND CORROSION DIVISION

Thomas D. Coyle, Chief 21

Corrosion and Chemical Stability of Materials

in Service Environments . 23

High Temperature Chemical Stability of Materials

for Processing and Service 47

Recycled Oil Program 63

Other Division Activities 73

FRACTURE AND DEFORMATION DIVISION

Richard P. Reed, Acting Chief 99

Fracture Mechanisms and Analyses 103

Durability of Ceramics and Composites Ill

Elastic-Plastic Fracture Mechanics 127

Other Division Activities 137

POLYMER SCIENCE AND STANDARDS DIVISION

Ronald K. Eby, Chief 163

Polymer Standards for Control and Equity 165

Tests, Standards, and Characterization for

Manufacturing and Durability of Dental and

Medical Materials 179

Mechanical Durability of Polymers for Design

and Use 193

Migration and Durability of Polymers 217

Dielectric and Piezoelectric Plastics Performance . . . 231

Other Division Activities 247

iii
METALLURGY DIVISION

Robert Mehrabian, Chief 279

Alloy Structure, Properties, and Standards for

Quality Control 283

Synchrotron Radiation Research for Materials Science . 283

Metallurgical Processing for Alloy Durability 307

Alloy Durability for Wear Applications 319

Chemical Metallurgy for Durability 328

Other Division Activities 342

CERAMICS, GLASS, AND SOLID STATE SCIENCE DIVISION

H. P. R. Frederikse, Chief 363

Structural Chemistry for Ceramic Processing and

Durability 367

Structural Methods for Processing, Manufacturing,

and Durability 379

Properties, Structure, and Standards for Glass

and Optical Materials 403

Durability of Ceramics and Glass in Service

Environments 435

Other Division Activities 443

REACTOR RADIATION DIVISION

Robert S. Carter, Chief 457

Reactor Operation and Services 461

Neutron Scattering Characterization of Materials for

Advanced Technologies 465

Neutron Diffraction and Radiographic Methods for

Materials Utility and Durability 469

Advanced Neutron Methods 473

Other Division Activities 475

APPENDIX

NBS Organizational Chart 476

NML Organizational Chart

*

’ 477

CMS Organizational Chart [

*

* 478

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I. Introduction

The Center for Materials Science (CMS) was formed in 1978 as part

of a general reorganization of the National Bureau of Standards. The

Center is located within the National Measurement Laboratory (NML), one

of the two principal laboratories comprising NBS. Figures 1, 2, and 3

give the organizational structure of the CMS, NML, and NBS, respectively.

The CMS is one of the largest Centers at NBS. It has approximately 344

staff members; * 68 percent are professionals, of which 61 percent hold

Ph.D. degrees. The operating budget of the Center for FY80 amounted to ^ $23 M.

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 material s—metal s , polymers, and inorganic

materials. Center activities currently focus on those aspects of

materials research involving processing science, structure/property

science, and durability science. More specifically the Center

Develops and maintains the scientific competences and experimental

facilities necessary to provide the Nation with a central basis

for uniform physical measurements, measurement methodology, and

measurement services necessary to define the properties and

performance of materials and other essential areas in the materials

science discipline.

Provides Government, industry, universities, and consumers with

essential standards, measurement methods, data, concepts, and

information concerning metals, polymers, and inorganic materials.

Characterizes the structure of materials, chemical reactions, and

physical properties which will lead to the safest, most efficient

uses of materials, improve materials technologies, and encourage

recycl i ng.

Obtains accurate experimental data on the behavior and properties

of materials over time under service conditions to assure effective utilization of raw materials and manufactured materials.

Provides technical information in the form of reference data,

materials measurement methods, and standards to materials

processors, designers, and materials users to enable them to

select cost effective combinations of materials, processes,

designs, and service conditions.

The Center is organized in six Divisions, each having responsibilities in different areas of materials science. These Divisions vary in

their balance between theory and experiment, between direct standards

work and research, and in their orientation toward industrial and Govern1
merit needs and the needs of other components of the scientific and

technological community. 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 FY80 technical activities encompassed by the various

tasks are given in the following sections.

Task Numbers, Titles, and Leaders

Center Office

12101 Materials Measurement Services J. B. Wachtman, Jr

Chemical Stability and Corrosion Division

12111 Corrosion and Chemical Stability of

Materials in Service Environments

T. D. Coyle

12112 High Temperature Chemical Stability

of Materials for Processing and

Service

T. D. Coyle

Fracture and Deformation Division

12121 Fracture Mechanisms and Analyses R. P. Reed

12122 Durability of Ceramics and Composites S. M. Wiederhorn

12123 Elastic-Plastic Fracture Mechanics H. I. McHenry

Polymer Science and Standards Division

12132 Polymer Standards for Control and

Equity

L. E. Smith

12133 Predictive Models for Polymer

Performance

B. M. Fanconi

12134 Chemical Durability of Plastics in

Use

L. E. Smith

12135 Manufacture and Durability: Dental

Medical Materials

J. M. Cassel

12136 Mechanical Durability of Plastics

for Design and Use

B. M. Fanconi

12138 Migration and Durability of Plastics

in Use

L. E. Smith

12139 Dielectric Plastics Design and

Performance

M. G. Broadhurst

Metal 1 urqy Division

12142 Alloy Structure, Properties, and

Standards for Quality Control

J. A. Simmons

51105 Synchrotron Radiation Research for

Materials Science

M. Kuriyama

12143 Metallurgical Processing for Alloy

Durabi 1 i ty

J. R. Manning

12144 Alloy Durability for Wear Applications A. W. Ruff

12145 Chemical Metallurgy for Durability L. H. Bennett

2
Ceramics, Glass, and Solid State Science Division

12151 Structural Chemistry for Ceramic

Processing and Durability

R. S. Roth

12153 Structural Methods for Processing

Manufacture and Durability

S. Block

12154 Property, Structure, and Standards

for Glass Processing and Manufacture

W. K. Haller

12155 Durability of Ceramics and Glass in

Service Environments

H. P. R. Frederikse

Reactor Radiation Division

12161 Reactor Operation and Services T. M. Raby

12162 Neutron Scattering Characterization

of Materials for Advanced Technology

J. J. Rush

51102 Advanced Neutron Methods J. M. Rowe

12163 Neutron Diffraction and Radiographic J. J. Rush

Methods for Materials Utility and

Durability

3


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OFFICE OF THE CENTER FOR MATERIALS SCIENCE

John B. Wachtman, Jr., Director

Darrell H. Reneker, Deputy Director

Samuel J. Schneider, Special Assistant for Programs

Bruce W. Steiner, Special Assistant for Planning and Programming

John D. McKinley, Special Assistant for Program Planning and

Initiation

Melvin Linzer, Leader, Signal Processing and Imaging Group

Robb M. Thomson, Center Scientist

John W. Cahn, Center Scientist

Jacob Mazur, Center Scientist

Margaret M. Barbosa, Secretary

Ellen T. King, Supervisory Editorial Assistant

CaRole J. Lamb, Editorial Assistant

M. Jocelyn Castle, Senior Administrative Officer

Elizabeth Kershow, Administrative Officer

Evelyn C. Maxwell, Administrative Officer

Marian L. Slusser, Administrative Officer

Ruth A. Schmeit, Administrative Assistant

Diane Shields, Administrative Assistant

Sara M. Thomas, Administrative Assistant

Patricia F. Hernandez, Administrative Aide

The Center Office has the responsibility for providing the technical

and administrative framework for the planning and operation of the technical programs carried out by the six Divisions and. the Center Office

scientists. Efforts this past year have focused on. the development,

strengthening, and implementation of programs and plans of the Center.

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

through accomplishments of the Divisions, several of particular interest

merit mention here:

A Congressionally-mandated study of the costs of fracture to the

U.S. economy is being initiated by the Center. This will be

implemented under Center Office oversight beginning in FY81.

The Center's formal long-range (five-year) plan has been rewritten

and up-dated to reflect new competence building thrusts, new programmatic plans in innovative high performance materials, recent

shifts in task emphasis, and to review relevance of Center activities

to critical national issues in materials recently identified by the

National Materials Advisory Board (NMAB) of the National Academy of

Science (NAS).

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

the following technical meetings:
Fourth Annual Conference on Materials for Coal Conversion,

October 9-11, 1979

Workshop on Materials for Superconducting Magnets,

October 16-18, 1979

Conference on Implant Retrieval: Material and Biological

Analysis, May 1-2, 1980

Conference on Basic Optical Properties of Materials,

May 5-7, 1980

International Standards Organization Technical Committee 156

on Corrosion of Metals, June 1-16, 1980

Second International Symposium on Ultrasonic Materials Characterization, June 4-6, 1980

Inter- American Conference on Materials Technology, ASME,

August 12-16, 1980

Measurement Services

Task 12101

Although most of the program planning and laboratory activity in

the Center takes place in the six Divisions, a single task, Measurement

Services, in the Center Office takes a general view of American materials

science. This task assures adequate attention to major new challenges

and opportunities, particularly those that may affect two or more

Divisions. This activity also provides a window on policy studies in

the Executive and Legislative Branches. At the same time, through this

activity, the Center provides senior consultation to other agencies, to

other NBS Centers, and to CMS Divisions.

Signal Processing and Imaging

Subtask 1 of Task 12101

M. Linzer, S. I. Parks, S. J. Norton, and J. A. Abbott 1

Postdoctoral Research Associate

In the past year, emphasis was placed on various aspects of ultrasonic imaging and computerized tomography. A theoretical and experimental

analysis of texture in ultrasonic imaging was carried out. Studies of

cutting techniques for transducer arrays and tomographic image reconstruction from limited projections were completed. A collaborative effort

with the National Institutes of Health (NIH) Clinical Center showed

that an NBS-devel oped digital processing device was capable of diagnosing

diffuse liver pathology (e.g. , Gaucher's disease). Exact solutions were

obtained for the first time for three-dimensional reflectivity imaging

6
using broad bandwidth pulses. Inversion formulas were derived for three

transmit- recei ve apertures—plane, cylindrical, and spherical. Substantial progress was made in developing perturbation and iterative correction schemes for velocity tomography. The theoretical and computer

simulation phase of this activity is expected to be completed during the

first half of the next fiscal year and experimental demonstration of the

techniques in the second half.

Two papers were published, three accepted for publication, and a book. Ultrasonic Materials Characteri zati on , was edited.

Fracture Theory

Subtask 2 of Task 12101

R. M. Thomson

A rigorous statistical mechanical theory of reaction rates at the

tip of a fracture crack has been developed. This work puts the quasichemical approaches developed earlier on an adequate theoretical basis,

and predicts new phenomena associated with bridging reactions at the

crack tip which are yet to be observed. This paper was published during

the year.

A second paper co-authored with Fuller applied results of the first

paper to one-dimensional models, and developed laws for slow crack growth

velocities as a function of applied stress. This paper was published

during the year.

A third paper co-authored with Lawn and Fuller developed a fundamental theorem on the one-dimensional model of fracture which showed

that one could break down the effects of chemical reaction at a crack

tip into three separable physical effects: a) the chemical reaction

at the tip molecule; b) elastic response of the remainder of the

crystal; and c) the change in potential energy of external force systems.

This theorem should be important in developing detailed ideas about

crack tip chemistry, because of the absence of cross terms between the

linear response of the lattice, and the response of the nonlinear

reacting molecule at the tip. This paper is in press.

A fourth paper was co-authored with Fuller and Wiederhorn and

delivered at a limited attendance international conference by Wiederhorn

in Cambridge. The paper reviewed NBS theoretical ideas and experimental

results in brittle fracture. The new result was a demonstration of how

to generalize the concept of activation volume to crack growth laws.

A fifth paper now being prepared has reopened the theory of fracture

in 2D and 3D discrete lattices. A new formulation has been developed

in terms of lattice Greens functions. It is shown that all lattice

1
theories must yield a finite lattice trapping—a controversial point of

rigor until now. Asymptotic Greens functions were developed which vastly

improve the ease and speed of discrete lattice calculations. Methods

were developed for calculating activation energies and activation volumes

for a variety of force laws. Methods were developed for handling general

nonlinear force laws at the crack tip which were analytic and do not

require numerical computer solution. And finally, the theorem that the

overall response of a material can be broken into three separate parts

(crack tip nonlinear atomic pair, linear lattice, and external force)

is shown to be a completely general result for two and three dimensions

as well as one.

New results have been obtained, but not yet in the write-up stage

which a) show that a sharp fracture always has a lA/r stress singularity

at its tip because of limited screening due to dislocations, and b)

developed rigorous solutions of idealized fracture modes which confirm

an earlier approximate result which has become controversial regarding

how the critical stress to fracture should depend upon the surface free

energy. These results should lead to predictions of actual fracture

criterion laws for brittle materials, ultimately.

Theoretical Materials Stability

Subtask 3 of Task 12101

John W. Cahn

This work addressed fundamental factors in the stability of

materials. It is carried on with a wide variety of colleagues. This

past year we have worked with colleagues in Montpellier, in Cambridge

(Massachusetts), and in Malibu. The activity can be divided into two

general areas, interface activity and bulk stability.

In addressing interface activity, they have shown first that in

any two-phase mixture of fluids near the critical point, one of the

phases will wet a third phase so that contact with the other phase is

excluded. The surface layer of the wetting phase continues to exist

past the onset of instability in the bulk phase. This perfect wetting

terminates in a first-order transition which has been found and is being

studied. For solids, a satisfactory microscopic theory for antiphase

domain wall, motion in ordered structures has been demonstrated. The

velocity of motion is predicted to be proportional to mean curvature,

but independent of surface-free energy, in contrast to the unsatisfactory

predictions of previous models. The behavior of FeAl and Cu 3 Au alloys

has been demonstrated to be consistent with that predicted.

For the growth of monotectic solid composites from solution,

theoretical factors have been re-examined. There are indications that

phase growth may be determined by the velocity necessary to overcome

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disjoining pressure, which will be small. Critical experiments have

verified the analysis: variation in pressure and ternary additions.

Perfect wetting should occur close to the critical temperature.

Equilibrium antiphase and interphase boundaries in the CuAu system

have been examined. Near the congruent point antiphase boundaries undergo a second order surface phase transition to an interfacial layer

resembling inhomogeneous CuAu. One of the antiphase boundaries is

predicted to be perfectly wet by the disordered phase at the disordering

temperature.

A two-dimensional lattice-gas model of a grain boundary has been

investigated and shown to exhibit a phase transition that can be

described as surface melting.

The role of higher order (non-pairwise) energies in FCC alloys has

been examined and found to lead to a prediction of either symmetric or asymmetric versions of Cu-Au phase diagrams.

General conditions have also been established for multiphase equilibrium of anisotropically stressed solids in contact with fluids. The

equilibrium obtained is sensitive both to the presence of vacancies and

the nature of the phase contact. Equilibria at coherent boundaries are

insensitive to the existence of vacancies, while vacancies do' govern

the equilibrium of incoherent phases.

Finally, reports that low temperature diffusion can cause grain

boundaries to migrate and thereby provide a mechanism of greatly enhanced

(by factors in excess of 10 9

) diffusion have been confirmed and investigated in greater detail. The effect exists for at least six different

metallic systems and for symmetric as well as unsymmetric boundaries.

Processes Involving Conformational Changes in Polymers

Subtask 4 of Task 12101

Darrell H. Reneker, J. Mazur

The infrared spectrum of polyethylene in which five percent of the

carbon atoms are doubly deuterated contains bands which are attributed

to trans-trans and trans-gauche dihedral angle sequences. These bands

were used to analyze conformational disorder in crystalline polyethylene.

Experimental results show that trans-gauche sequences occur in crystalline polyethylene and that the number of such sequences increases in

the temperature range between 60° and 120 °C.

A defect in a polyethylene crystal known as a point dislocation or twist dispi ration loop, which transports a chain along its axis through a crystal by a process appropriately called reptation, involves several

trans-gauche sequences. The thermal generation and subsequent motion of

9
such defects can account for a variety of experimentaly observed phenomena in polyethylene. The motion of the defect is being modeled mathematically at the level of conformational changes within the molecule

and also by considering the defect as a point diffusing along a straight

polymer chain segment bounded by two folds. The defect motion is

considered to be driven both by fluctuating forces derived from thermal

motions and by microscale forces derived from macroscopic strain. The

theoretical analysis uses data from infrared and nuclear magnetic

resonance spectroscopy to characterize the defects. The resulting

model for dynamics of defect motion connects data from thermal annealing,

dielectric relaxation, and mechanical relaxation experiments and thereby

leads to improved understanding of the useful macroscopic properties of

polymers.

The transport of polyethylene in the melt by a reptation process

is being investigated. The self diffusion coefficient or molten polyethylene measured with a magnetic field gradient nuclear magnetic

resonance method is being compared with diffusion coefficients measured

by observing the changes in concentration of perdeuterated molecules

near a boundary between polyethylene and polyethylene containing

perdeutero-polyethylene as a function of time. This work extends the

investigation of molecular transport by reptation into the melt.

Energy minimization calculations -are being used to investigate the

effects of fold geometry and temperature on the overall energy of a single

crystal. The results of these calculations are being correlated with

observations of changes in crystal morphology which occur with increasing

crystallization temperature.

The above work is being done in cooperation with collaborators in

the Polymer Science and Standards Division, the University of California

in Berkeley, and the Josef Stefan Institute in Ljubljana, Yugoslavia.

10
Other Activities in the

Office of the Center for Materials Science

Invited Talks

Polymer Morphology and Chain Transport Mechanism

Boris Kidric Institute, Belgrade, Yugoslavia

D. H. Reneker

September 1979

Properties of Polymers Including Chain Transport and Piesoelectric

Effects

Josef Stefan Institute, Ljubljana, Yugoslavia

D. H. Reneker

September 1979

Role of Defects in Transport of Chains in Polymer Crystals

Northwestern University, Evanstan, Illinois

D. H. Reneker

April 1980

Colloquium, American Ceramic Society

Physics Department, Rutgers University, New Brunswick, New Jersey

R. M. Thomson

April 1980

Trends in Materials Science in the 80 1 s and Some Associated Information Service Needs

Metals/Materials Division, Special Libraries Association

Washington, D.C.

John B. Wachtman, Jr.

June 1980

Mechanical Properties and Failure Avoidance

Committee on Capital Construction

Beijing, Peoples Republic of China

John B. Wachtman, Jr.

June 1980

Erosion of Ceramics

Committee on Capital Construction

Beijing, Peoples Republic of China

John B. Wachtman, Jr.

June 1980

The Program of the Center for Materials Science, National Bureau

of Standards

Committee on Capital Construction

Beijing, Peoples Republic of China

John B. Wachtman, Jr.

June 1980

11
Mechanical Properties and Failure Avoidance

Shanghai, Peoples Republic of China

John B. Wachtman, Jr.

June 1980

Erosion of Ceramics

Shanghai, Peoples Republic of China

John B. Wachtman, Jr.

June 1980

Research on Ceramics in the Peoples Republic of China--A Trip

Report

National Bureau of Standards

John B. Wachtman, Jr.

July 1980

Measurement Science and Technology at the National Bureau of

Standards

Engineering Foundation Conference on National Materials Policy

New England College, Henniker, New Hampshire

John B. Wachtman, Jr.

July 1980

Spectroscopic Investigations of Conformational Irregularities

in Crystalline Polymers

Polymers Department, Weizmann Institute of Science

Rehobot, Israel

J. Mazur

July 1980

Spectroscopic Investigations of Conformational Irregularities

in Crystalline Polymers

Faculty of Chemistry, Israel Institute of Technology

Haifa, Israel

J. Mazur

August 1980

Assessment of MHD Technology

National Science Foundation Workshop

Washington, D.C.

S. J. Schneider

September 1980

Performance and Durability of Materials

Johns Hopkins University, Baltimore, Maryland

John B. Wachtman, Jr.

September 1980

Performance and Durability of Materials

Pennsylvania State University, State College, Pennsylvania

John B. Wachtman, Jr.

October 1980

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Technical and Professional Committees and Leadership

Federation of Materials Societies

Committee on Materials Durability and Conservation

J. B. Wachtman, Jr., Chairman

Advisory Committee to Materials Research Laboratory, Pennsylvania

State University

J. B. Wachtman, Jr. , Member

Corporation Visiting Committee, Department of Materials Science

and Engineering, Massachusetts Institute of Technology

J. B. Wachtman, Jr. , Member

American Physical Society

J. B. Wachtman, Jr., Fellow

R. M. Thomson, Fellow

J. W. Cahn, Member

Committee on Applications of Physics

J. B. Wachtman, Jr. , Member

Division of High Polymer Physics

D. H. Reneker, Program Chairman

Editorial Committee, Annual Review of Materials Science

J. B. Wachtman, Jr. , Member

Mining/Metallurgy/Ceramics/Materials Engineering Peer Committee

National Academy of Engineering

J. B. Wachtman, Jr. , Member

Materials Science and Technology Committee

J. B. Wachtman, Jr. , Member

Committee on Materials (COMAT)

J. B. Wachtman, Jr., Alternate Member

American Ceramic Society

J. B. Wachtman, Jr.

,

Member

S. J. Schneider, Member

J. W. Cahn, Member

R. M. Thomson, Member

Executive Committee

J. B. Wachtman, Jr.

,

Member

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Rules Committee

J. B. Wachtman, Jr. , Member

Refractories Division

S. J. Schneider, Editorial Chairman

Executive Committee

S. J. Schneider, Member

American Society for Testing and Materials

S. J. Schneider, Member

J. B. Wachtman, Jr. , Member

R. M. Thomson, Member

C8 Refractories Committee

S. J. Schneider, Member

E20 Temperature Committee

S. J. Schneider, Member

Award of Merit Committee (National)

S. J. Schneider, Member

American Chemical Society

J. B. Wachtman, Jr., Member

J. D. McKinley, Member

US-USSR Cooperative Program on MHD

Steering Committee

S. J. Schneider, Member

Interamerican Conferences on Materials Technology

Executive Committee

S. J. Schneider, Member

IUPAC Conferences on Refractories for Energy Applications

Planning and Program Committees

S. J. Schneider, Member

Committee on Dynamic Compaction of Metal and Ceramic Powders

J. D. McKinley, Liaison Representative, NBS

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Solid State Sciences Committee, National Research Council

Committee on Applied Physics

R. M. Thomson, Member

Plastics Institute of America

Research Committee

D. H. Reneker, Member

National Archives and Records Service

Advisory Committee on Preservation

D. H. Reneker, Member

Polymer Science and Engineering

Board of Editors

D. H. Reneker, Member

CRC Critical Reviews in Solid State Physics

Board of Editors

D. H. Reneker, Member

IUPAC 79 “Macromaining"

D. H. Reneker, Session Chairman

The Optical Society of America

Washington Area Drive for National Optics Center Fund

B. W. Steiner, Chairman

Technical Council

B. W. Steiner, Chairman

Executive Committee

B. W. Steiner, Member

Liaison with Society for Photo Optical Instrumentation Engineers

B. W. Steiner

15
American Institute of Metallurgical Engineers

Heat Treating Committee

J. W. Cahn, Member

Solidification Committee

R. M. Thomson, Member

J. W. Cahn, Member

National Academy of Sciences

J. W. Cahn, Member

American Academy of Arts and Sciences

J. W. Cahn, Fellow

R. M. Thomson, Member

American Society for Metals

R. M. Thomson, Member

Thermodynamics Committee

J. W. Cahn, Member

Archeological and History Committee

J. W. Cahn, Member

16

iiiiuMimiiiHimiinuMmi nHnnnBBin msn
Publ i cations

Further Development and Clinical Evaluation of the ExpandingAperture Annular Array System

S. I. Parks, M. Linzer, and T. H. Shawker

Ultrasonic Imaging, 1, 378-383 (1979)

Raman Spectra of n-alkanes. I. Raman Intensities of Longitudinal

Acoustic Modes

J. Mazur and B. Fanconi

J. Chem. Phys., 71, 5069 (1979)

Development of Tailored Materials and Processes

John B. Wachtman, Jr., and Bruce W. Steiner

Materials Eng., 91, 48 (1980)

Amplitude Analysis of Pancreatic B-Scans: A Clinical Evaluation

of Cystic Fibrosis

T. H. Shawker, S. I. Parks, M. Linzer, B. Jones, L. A. Lester, and

V. S. Hubbard

Ultrasonic Imaging, 2, 55-66 (1980)

Materials for Open Cycle MHD Generators

S. J. Schneider, H. P. R. Frederikse, T. Negas, and G. Rudins

Chapter 3, Current Topics in Materials Sciences, Vol. 4, E. Kaldis,

North Holland Publishing Co. (1980)

Theory of Chemically Assisted Fracture I. General Reacton Rate

Theory and Thermodynamics

R. M. Thomson

J. Matls. Sci., 15, 1014 (1980)

Theory of Chemically Assisted Fracture II. Atomic Models of Crack

Growth

E. R. Fuller, Jr., and R. M. Thomson

J. Matls. Sci., 15, 1027 (1980)

Atomic Modeling of Chemical Interactions at Crack Tips

R. M. Thomson, B. R. Lawn, and E. R. Fuller, Jr.

Acta Met (in press)

Tomographic Image Reconstruction from Limited Projects Using

Iterative Revisions in Image and Transform Spaces

T. Sato, S. J. Norton, M. Linzer, 0. Ieda, and M. Hirama

Appl . Optics (accepted for publication)

Reflectivity Imaging in Three Dimensions: Exact Solutions for

Plane, Cylindrical, and Spherical Apertures

S. J. Norton and M. Linzer

IEEE Trans. Biomed. Eng. (accepted for publication)

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Optical Interferometric Visualization and Computerized Reconstruction of Ultrasonic Fields

F. P. Higgins, S. J. Norton, and M. Linzer

J. Acous. Soc. Amer. (to be published)

Micro Mechanisms of Crack Growth in Ceramics and Glass in Corrosive

Environments

R. M. Thomson, S. M. Wiederhorn, and E. R. Fuller, Jr.

Proc. International Conference on Fundamentals of Fracture,

Cambridge, England (to be published)

Measurement Science and Technology at the National Bureau of

Standards, Center for Materials Science

J. B. Wachtman, Jr., and J. D. McKinley

Proc. VI Henniker Conference on National Materials Policy

(to be published)

Sponsored Conferences

Fourth Annual Conference on Materials for Coal Conversion and

Utilization

National Bureau of Standards

October 1979

Fifth International Symposium on Ultrasonic Imaging and Tissue

Characterization

National Bureau of Standards

June 1980

Second International Symposium on Ultrasonic Materials Characterization

National Bureau of Standards

June 1980

Fracture Workshop

DARPA Materials Research Council

La Jolla, Cal i form*

July 1980

Metals Processing, ASME

San Francisco, California

August 1980

Incentives and Disincentives for Conservation of Materials and

Effective Utilization of Materials Through Product Design

Session at VI Henniker Conference on National Materials Policy

New England College, Henniker, New Hampshire

August 1980

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Fifth Annual Conference on Materials for Coal Conversion and

Utilization

National Bureau of Standards

October 1980

NATO Fracture Conference

Spril 1981

Mechanical Properties Symposium

American Physical Society

1981

Topical Conference on Fundamental Physics of Mechanical Behavior

for American Physical Society

1981

Fracture Fundamentals Conference

1982

Books

Ultrasonic Materials Characterization

H. Berger and M. Linzer, Eds.

American Society for Nondestructive Testing

Materials Aspects of World Energy Needs

J. B. Wachtman, Jr., Ed.

National Research Council

Issues and Engineering Education

National Academy of Engineering

J. B. Wachtman, Jr., Ed.

Special Reports

Evaluation of Ultrasound Echo Amplitude Measurements for Assessment

of Bond Integrity in Zirconium Alloy Samples

M. Linzer, J. G. Abbott, and S. I. Parks

Report on Westinghouse Contract No. EY-76-C-11-0014

An Assessment of Open Cycle Magnetohydrodynamics (MHD) Technology

S. J. Schneider, T. Negas, W. R. Hosier, and J. D. McKinley

August 1980

19

i
I

i

I

tm
CHEMICAL STABILITY AND CORROSION DIVISION (561)

Thomas D. Coyle, Chief

L. L. Ware, Administrative Aide

M. L. Seebode, Clerk Typist

M. E. Lukens, Clerk Typist

M. S. O'Connor, Student Aide

R. M. Gregory, Clerk Typist

The Chemical Stability and Corrosion Division provides a focus,

within the NBS Center for Materials Science, for research and measurement

activities related to the chemical stability and reactivity of materials

in their service environments. The Division carries out field and

laboratory research to assess the resistance of materials to chemical

and biological degradation under service conditions. It identifies and

characterizes the mechanisms underlying corrosion, corrosion inhibition,

and molecular level chemical transformations critical to materials

stability and processing and to the environmental impact of materials

use. As required, it develops measurement methods for quantitative

characterization of degradation processes, test methods to predict inservice durability, and appropriate standards.

The Division's accomplishments during FY80 are described in the

following pages. The program is described here in terms of three tasks.

One of these emphasizes metallic corrosion and the chemical stability of

materials in ambient service environments. A second focuses on chemical

processes affecting materials durability and processing at high temperatures. A third area of activity includes work on the chemical properties

and performance of lubricants in support of the NBS Recycled Oil Program.

Research is discussed under subtasks of these three tasks which comprise

groups of individual but integrated research projects.
' '

22 «««-
CORROSION AND CHEMICAL STABILITY OF MATERIALS IN SERVICE ENVIRONMENTS

Task 12111

The objective of the work carried out under this task is to provide

data, measurement methodology, test methods, and standards required in

processing, design, manufacture, and use; to enhance chemical durability

of materials (including corrosion resistance); and to reduce adverse

impacts of chemical and biodegradation of materials on health, safety,

and the environment.

The technical activities fall into two subtask areas. One subtask

emphasizes metallic corrosion and protective coatings. The other subtask focuses on measurement methodology and mechanistic understanding of

chemical and biodegradation processes affecting several classes of

materials.

Corrosion and Electrodeposition

Subtask 1 of Task 12111

J. Kruger, N. K. Adams, U. Bertocci , W. E. Crummer,

C. F. Derr, E. Escalante, J. L. Fink, W. F. Gerhold, S. Ito,

C. E. Johnson, D. R. Kelly, D. S. Lashmore, J. S. Mullen, F. Ogburn,

E. N. Pugh, J. J. Ritter, M. J. Rodriguez, B. T. Sanderson, J. Smit,

J. P. Young

Technical activity in this area is aimed at providing a scientific

base, data, measurement methodology, test methods, and standards to

advance corrosion prevention and coating technologies. It carries out

this objective by working on projects that range from test method development through field and laboratory studies of corrosion resistance of

materials, to more basic investigations of corrosion mechanisms, and

coatings science.

Corrosion Science, Measurement, and Test Methods : This area seeks to

develop, improve, and evaluate test methods which will measure pitting,

crevice and stress corrosion, hydrogen embrittlement, gaseous oxidation,

underground, marine, and atmospheric corrosion in order to provide

industry and Government with improved test methods. To accomplish these

objectives, the approach is to apply the newest techniques provided by

electrochemistry , metallurgy, surface physics, and chemistry to a study

of corrosion processes and to eventually develop from these studies

simpler techniques that can be applied by testing laboratories.

Significant technical activities during FY80 in this area have been

the following:

(1) The feasibility of deriving useful information from a new technique that can make simultaneous ellipsometric and electrochemical

measurements on iron protected by an organic coating has been demonstrated.

This work was partially supported by the Office of Naval Research and

seeks to develop a better understanding of corrosion processes occuring

under paints in order to provide a basis for the development of coatings
with enhanced corrosion resistance. Results obtained from polished iron

specimens protected by a 10-30 pm coating of cellulose nitrate and immersed in dilute NaCl solution indicate that active corrosion is a highly localized process. A major portion of the remaining surface is

subjected to a predominately alkaline environment as a consequence of

the cathodic reduction of 02

. The latter regions, when observed ellipsometrically show both surface roughening and a substantial thickening of

the existing substrate oxide film. This behavior of iron in highly

alkaline media has been experimentally verified by ellipsometric studies

of iron in saturated NaOH.

The presence of an inhibitor ion such as Cr0 4

2 appears to attenuate

both surface roughening and oxide film thickening, (see figure 1).

The topographical changes which occur on the substrate surface

under the coating (i.e. , surface roughening and oxide film thickening)

are believed to contribute to the early stages of coating failure in

that they promote loss of adhesion.

(2) Further progress has been made in the development of electrochemical noise measurements and their application to the study of corrosion

processes. This work, partially supported by the NBS Office of Nondestructive Evaluation, promises to give new insights into corrosion mechanisms

as well as provide the basis for new test methods. Improvements in our ability to interpret corrosion noise measurements were achieved during

the past year when it was shown that by calculating the cross-power

spectrum between the input (the electrode potential) and the output (the

cell current) of an electrochemical system under potentiostatic conditions,

it was possible to identify which part of the cell current is the response

to the input voltage and which part is caused by random fluctuations of

the parameters characterizing the electrode. The noise introduced by

the amplifiers can thus be measured separately and then subtracted from

the signal. Using this new refinement of the technique it could be

shown that on aluminum the degree of random fluctuations below the

pitting potential is so low that the picture of the protective film as being in a state of dynamic equilibrium with continuous breakdown and

repair does not seem to be supported by the experimental evidence.

A new application of the electrochemical noise measurements made

during the past year involved an examination of the dynamic processes

occurring on the corroding surface of an amorphous alloy, which is

supposed to have superior corrosion resistance. Figure 2 shows clearly

the remarkable difference in the noise spectra of the amorphous material

and the same alloy after being crystallized. The latter is seen to have

a much greater tendency to localized attack, no doubt because of structural

inhomogenity of the passive film. Moreover, the noise measurements have

revealed that the superior resistance to breakdown of the passive film

in the amorphous alloy is not a result of the static properties of this

film because the overall current densities observed did not differ

greatly when comparing the crystallized and amorphous alloys. Rather,

the greater resistance to breakdown of the amorphous alloy lay in the

ability of its more homogeneous film to inhibit the dynamic processes

24
The changes with time of the optical parameters A and d>, which

indicate metal roughening and oxide film growth, potential

(4>Fe ) and pH for (a) iron covered with collodian and_immersed

in 0.05 N NaCl , and (b) iron with collodian and Cr0 4

2 islands

in 0.05 N NaCl

Figure 1.
Amplitude,

A/cm'

2

VlHz

o

10

10

10

Frequency, Hz

Figure 2. Noise current spectra for amorphous and crystalline

Fe 32 Ni 36 Cr 14 P 12 8 6 in 1 M H 2 S0 4

. Curves 1 and 3 are at potentials where pitting should not occur; curves 2 and 4 are above

or at potentials where pitting should be possible.

26
(probably repeated breakdown-repair events) that result in electrochemical noise. These results with the amorphous and recrystal 1 ized alloys

bolster the suggestion that the breakdown mechanism involves a dynamic

fluctuating set of events (for example, damaging species penetration)

rather than a steady deterioration of the properties of the passive

film.

(3) A new program in stress corrosion and hydrogen embrittlement

was started during the past year. A major aim of this new effort is to

evaluate and develop methods for stress-corrosion testing. Both the

double-torsion and s low-strain-rate methods are currently being used to

evaluate the stress-corrosion susceptibility of high-purity Al-Zn-Mg

alloy. The former method yields data on the dependence of the crack

velocity, V, on the stress intensity, K, and on K^scc, the stress intensity at which crack growth becomes negligibly small; the latter measures

susceptibility more indirectly from the reductions in strain to fracture

and maximum stress. Work on the effects of heat treatment on the performance, of- the A1 alloy was started using both methods to compare the

respective rankings. During the year, work carried out in conjunction

with the Univeristy of Illinois at Urbana-Champaign has employed a load-pulsing technique which provides a convenient and simple method of

determining the velocity of stress-corrosion cracks. In this technique,

small load pulses are superimposed onto an otherwise constant tensile

load and, in the case of transgranular stress-corrosion cracking of

austenitic stainless steels and alpha-brasses, the pulses were found to

produce markings on the fracture surfaces which delineate the instantaneous positions of the crack front. The crack velocity can then be

obtained from the spacing between the crack- front markings, Ax, measured

with the SEM, and the time interval between pulses, At. Tests to date

indicate that the velocity is not influenced by the pulsing. The tests

are being extended to the Al-Zn-Mg alloy to compare the plateau velocity,

i.e. , the velocity in the stress- independent region of the V-K curve,

determined by the load-pulsing technique with that obtained in the

double-torsion method.

Interpretation of the results of stress-corrosion tests requires a knowledge of the mechanisms of these critically important fracture processes, and consequently efforts were also directed to this area. The

load-pulsing method has recently been used to address the controversial

question of whether the propagation of transgranular stress-corrosion

cracks is a continuous (dissolution) or discontinuous (mechanical)

process. In tests on a Type 310 austenitic stainless steel, Ax, was

found to decrease progressively with decreasing At until a limiting

value of ~ 0.5 pm was attained (for At ^ 15 s). The limiting value is

considered to correspond to the distance of discontinuous crack advance

under normal constant- load conditions. Note that if propagation were

continuous, Ax would decrease continuously to zero. Studies of the

dependence of Ax on At have now been extended to alpha-brasses and to

the Al-Zn-Mg alloy to determine the generality of the effect. Another

key mechanistic issue concerns the role of hydrogen in the stresscorrosion process, and work was started to study both alpha-brasses and

the A1 alloy. In the latter case, the occurrence of internal hydrogen
embrittlement is well established, and work was initiated to compare the

characteristics of this phenomenon with those of conventional stresscorrosion cracking. In the case of the brasses, work has been started

to establish whether hydrogen embrittlement can in fact occur in copper

alloys.

(4) Two new joint research efforts were initiated in FY80 with

other Divisions in the Center for Materials Science. Both of these

projects have as their aim the development of a better understanding of

how alloy composition and structure affect the passive layers that

control corrosion processes. The first is in collaboration with Dr. D. M. Sanders of the Ceramics, Glass, and Solid State Science Division. It

is concerned with determining the role played by alloying elements in

influencing the properties, especially structure, of passive films. The

work uses the new apparatus built by Dr. Sanders and his colleagues that

is capable of producing synthetic oxide films of different compositions

and being capable of i_n situ analysis of such films using four different

surface analytical'tools. An electrochemical method for evaluating the

ability of passive films to resist breakdown has been set up. The

second research program initiated is in collaboration with Drs. M. Kuriyama

and G. G. Cohen of the Metallurgy Division. This work is aimed at using

synchrotron radiation to study passive films on metal surfaces. Work

has been started to study the passive film on copper, iron, and chromium

using EXAFS.

(5) Efforts to control the 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 considerable progress

was made on a project for the Federal Highway Administration that seeks

to develop a technique for measuring the corrosion of steel in concrete.

During the first year of this work, four polarization techniques were

used to measure the corrosion of steel in concrete. These four polarization techniques were chosen as a result of a critical review of the

literature (NBS Special Publication 550). These techniques, (Stern and

Geary's linear polarization, Mansfeld's polarization resistance, Barnartt's

three point method, Schwerdtfeger 1 s break in the curve), were applied to

several concrete slabs (60 x 30 x 5 cm) each containing three steel

bars. Because of the high resistivity environment of the concrete, it was necessary to compensate for the IR error generated during polarization.

The weight loss calculated from these electrochemical measurements was compared to gravimetric weight loss measurements of the bars. It was found that the Stern-Geary method gave the best agreement with actual

weight loss. Progress has been made toward developing a microprocessor

controlled instrument to make the polarization measurements in a simple

automatic fashion in the field. A parallel study on the effect of Cl

concentration, oxygen concentration, pH, and moisture content on the

corrosion of steel in concrete revealed that it is necessary that the

chloride contaminated concrete go through a drying cycle to initiate the
corrosion of steel. This concentrated the chloride and oxygen sufficiently

so that film breakdown occurs. Once this takes place, the corrosion

process lowers the pH locally allowing corrosion to continue.

(6) A new project under the sponsorship of the Electric Power

Research Institute (EPRI) was started in October 1979. This project

continues work originally supported by Department of Energy (DOE) that

seeks to develop test methods for the detection of dangerous corrosion

conditions that can exist when cables for the transmission of electric

power are installed underground. Since such underground cables have

been in use, their copper concentric neutral wires have been found to

undergo corrosion in a number of installations. This new project seeks

to evaluate the applicability of polarization and electrochemical noise

measurements as jn situ methods to detect concentric neutral wire corrosion.

The new EPRI project's work on the evaluation of the polarization

method has involved the installation during the past year of two sets of

50 m cables at a test site on the NBS grounds. Each set is made up of

two parallel 50 m cables. Imposed on the concentric neutral wires of

one set is an ac signal sufficient to develop a current density of

IpA/cm2 to ground simulating an operating cable. The second set is ac

free. The corrosion of both sets was measured by polarization techniques,

and indications are that the cables with ac are deteriorating at a greater rate than those without imposed ac. The distribution of current

over the cable during polarization has also been investigated. The

current distribution is important since it is necessary for the calculation

of corrosion current density.

Automation of the measurements at the field site by personnel in

the Electrical Measurements and Standards Division has progressed to the

point that an automatic IR compensating circuit has been developed and

made. It incorporates a modification of the Wheatstone bridge in a Holler circuit using a variable voltage source to produce a bias voltage

in one of the legs of the bridge for balance. Results using a dummy

circuit to simulate a corroding cell indicate that IR balance is achieved

with 0.1 to 0.5 mv error. A mobile field laboratory is in the process

of being placed at the test site to house the automated equipment.

The stability of three types of permanent solid reference electrodes

has been measured. Of the three (Zn/ZnCl 2 , Cu/CuS0 4 , Zn), the Zn/ZnCl 2 has maintained a stability of ± 0.0004 V over a 60 day period. The bare

zinc electrode has shown the least stability at ± 0.060 V over the same

period. New electrodes have been made containing a small (0.1 to 1.0

percent) concentration of HgC

2 which may improve long-term stability.

Polarization and current distribution measurements have been made

on operating cables owned by Prince William Electric Cooperative, Manassas,

Virginia. The ac interference on our instrumentation has practically

been nonexistent with a maximum level of 1.5 mV peak to peak. The

measurements have been made without any serious technical problem.
The work in electrochemical noise measurements has developed an approach that enables the identification of which part of the corrosion

current is the response to input voltage signals and which part is

caused by random fluctuations characterizing the corrosion of the copper

concentric wires. Laboratory measurements on copper concentric wires

embedded in agar to simulate conditions in the soil have been started.

(7) Work has been completed on a Department of Transportation (DOT)

project that has used the slow strain rate test to determine the susceptibility of pipeline steel to stress corrosion in carbonate/bicarbonate

solutions. Smooth and notched round specimens were tested at room

temperature in a 1 N carbonate/bicarbonate solution at strain rates of

10 4 to 10 7 /s. The slow strain rate test was also modified to provide

cyclic loading around a set load. None of the specimens tested indicated

susceptibility to stress corrosion cracking. For comparison purposes,

several fracture mechanics compact tension specimens were tested in the

laboratory as well as being field tested in two underground burial sites

where the two soils have different corrosive properties. A final report

of this project has been completed.

Evaluation of Corrosion Resistance of Materials : This area has as its

objective the production of new corrosion resistance data of materials

(primarily metals) in environments of practical importance. As a consequence of pursuing this objective, test methods are sometimes developed

or those developed in the previously described area are adapted.

Significant technical activities during FY80 in the evaluation of

the corrosion resistance of materials have been the following:

(1) Progress continued on a project supported by DOE to assess the

corrosion resistance of candidate alloys for downstream components of

MHD systems. Using a simple burner rig, tubular specimens of Type 304

and Type 316 stainless steel were exposed to a seeded oxygen-propane

fueled hot gas stream under varied conditions of temperature, seed

composition, and propane-oxygen ratios. The specimens were subsequently

analyzed by optical, SEM and EDX techniques for signs of incipient or gross corrosion. In addition, some aspects of the geometry of the

seeded deposit on the specimen surface were determined.

Specifically, the specimens were stream seeded with K2 S0 4 or with

K2 C0 3

. Internal cooling maintained the specimen at either 400 °C,

500 °C or 590 °C in a fuel-rich or oxygen-rich hot gas stream; local

temperature at the specimen was approximately 1300 °C.

In every instance some degree of non-uniform attack was observed.

Generally the attack was most severe on the surface of the specimen

facing the hot gas stream. This area was also coated with a compact

deposit, the thickness and character being dependent on the exposure

variables. The remaining surface, the downstream side, was coated with

a thinner, powdery type deposit, also dependent on exposure variables.
SEM and EDX analysis of the interface region between the salt

deposits, compact or powdery, and the metal revealed reaction zones

containing species of the bulk material. In all cases for both Type 304

and Type 316 stainless steel, high concentrations of Ni were detected

immediately adjacent to the bulk material. Immediately beyond this is a zone containing a high concentration of Cr followed by a zone containing

a high concentration of Fe with some cases of no evidence of Ni.

In the coming year the evaluation of materials as described will

continue.

(2) Since 1967, the National Bureau of Standards under the sponsorship of the American Iron and Steel Institute has been involved in a study of the effectiveness of corrosion protection of steel in sea water

by a variety of systems. These systems consist of metallic and nonmetal! ic coatings, single system and two system coatings, and cathodic

protection of bare and coated steel. The degree of protection afforded

by these systems is measured annually using electrochemical techniques

in conjunction with visual and photographic records.

The annual on site evaluation develops data that lead to a better

understanding of the deterioration rate of these protection systems.

These data are then compared to the physical measurements made on piles

that have been extracted from the site for study.

These data show, for example, that coal tar epoxy alone is undercut

and damaged relatively fast, but when the same epoxy is used as an overcoat on a zinc- rich inorganic silicate coating, both benefit, and

the combination is very resistant to attack.

(3) Historically, 5-mil copper has been used as a shield material

in non-gopher infested areas with 10-mil copper being used in areas

requiring gopher protection for telephone cables. Bi-metallic shields

using copper and stainless steel have also been used in lieu of 10-mil

copper. Due to an increase in underground telephone cable installation

coupled with increasing cost and fluctuating availability of copper, a program was initiated by NBS and the Rural Electrification Administration

(REA) to develop and investigate metals or combinations of metals and

other materials for use as a substitute for copper in buried telephone

cables. REA estimates that the NBS work has an impact on 90 percent of

the $600 million industry producing and using the telephone cables,

whose design is based on the NBS program.

The corrosion behavior of many different shield systems utilizing

other metals or alloys and composite metals and plastics has been investigated over a six-year period at six NBS soil corrosion test sites.

Since initiation of the program, it has been expanded to include additional

systems. These systems are representative of advances in technology

with respect to manufacturing processes or techniques in addition to the

use of new materials.
The results to date show that some of the cable systems utilizing

aluminum alloy shields with ethylene/acrylic acid copolymer film coatings

provided good protection to the cable core in some of the less aggressive

soils. However, when coupled to copper, their performance was poor in one more of these soils. Good protection was afforded in all of the

soils by systems incorporating a Type 304 or Type 430 stainless steel

outer shield with an aluminum alloy inner shield separated by a polyethylene jacket.

Systems buried up to six years have been evaluated and a report

containing the results obtained from these tests should be completed in

the fall of 1980.

In 1977, this program was further expanded to include "buried plant

housings" which are used in the construction of telephone systems.

Representative samples, to be investigated over a six-year period, were

exposed at four of the N8S soil corrosion test sites and at two additional

sites (one, in northern Pennsylvania and the other along the seacoast in

South Carolina). Removal of the second set of "plant housings" exposed

for two years has been completed at five of the six soil sites. Exposure

of additional samples, representative of advanced technology in materials

fabrication has been initiated.

(4) Stainless steels have been proposed for use in underground

applications such as gas, water, telephone and electrical distribution

systems, ground rods, culverts, transformer cases, residential sewage

disposal, etc. In 1970, an investigation was initiated with partial

support from the American Iron and Steel Institute at six N8S soil test

sites to evaluate the corrosion behavior of stainless steels in underground service. This was expanded in 1972 and 1973 to include materials

representative of newer alloys. Aspects being studied include general

corrosion behavior, pitting and crevice corrosion, stress-corrosion

cracking, and hydrogen embrittlement. To date 1054 specimens have been

buried at each site for a total of 6324 at the six test sites. The

exposure periods chosen were one, two, four, eight, and X years. A

report containing the results obtained from specimens buried up to eight

years has been completed and the project has been terminated.

(5) With the support of DOE and the N8S Office of Recycled Materials,

a study has been initiated on the corrosion of metals and alloys used or under consideration for use in waste- to-energy systems. This study is

directed toward corrosion problems that may exist in incinerator systems

where refuse-derived fuels are manufactured. To date, NBS personnel

have made on site visits to several incinerators in order to determine

existing problem areas and to obtain samples (if available) for analysis.

Future plans include the placement of candidate materials in the form of

metal coupons in incinerator systems which can be monitored on a regular

basis in order to determine their corrosion behavior.

El ectrodeposition : This area seeks to develop new understanding of the

structure of electrodeposits and electrodeposition processes, to improve

current electrodeposition technology, to produce and develop new SRM's

that are necessary for the measurement technology used by the plating

industry and to devise new SRM's, requiring electrodeposition for their

fabrication, for use in nondestructive evaluation techniques.

32
Significant technical activities during FY80 in this area have been

the following:

(1) The three-year project for the Aluminum Association directed at

obtaining a better understanding of the factors that affect adhesion and

corrosion of electrodeposits on aluminum was completed during the past

year. Among a number of accomplishments achieved during the past year

the following two were most noteworthy:

(a) In work directed at obtaining a better understanding of

the effect of anodizing parameters on the adhesion' of electrodeposits on

A1 , it was shown that adhesion is an approximately linear function of

the applied voltage. Since the pore diameter (and the cell diameter)

also increases in a linear manner with the applied voltage, a relationship was thought to exist between adhesion and pore diameter. Moreover,

the greater the pore diameter, the less oxide there is per unit area of

the coating. This implies that the strength of the oxide itself is the

determining factor (or weak link) in adhesion of subsequent coatings to

the anodic film. It should be noted that the pore structure, especially

at higher voltages, does not vary much as one changes from one of the

three major electrolytes used for this process (sulfuric acid, oxalic

acid, and phosphoric acid) to another. Therefore, the adhesion does not

appear to be dependent upon the pore structure, but, rather, upon the

strength of the oxide itself and upon the percentage of oxide coverage

of the surface. The composition of the anodic film varies considerably

with the alloy and with the electrolyte. Therefore, the microstructure

of the oxide itself (not the pore structure) and its composition are the

determining factors.

(b) A theory which predicts the adhesive energy for metallic

coatings on metallic substrates was developed. The theory takes into

account the effect of structure through a parameter "a" which represents

the lattice parameter i_n the interface. This parameter is determined by

the orientation of both the substrate crystal and the coating crystal.

The adhesive energy as a function only of the structure is

2

K G a

E

ad = Wd-' ^

For f.c.c. materials, K = 3. G

q

is the shear modulus in the interface

which can be determined from the binding energy between the two metals

and d is the distance of closest approach. The lattice parameter in the

interface is given by

a 2a

c a

S a

c + a

s

[ 2 ]

where a^ and a

s are the (orientation dependent) nearest neighbor distances

in the coating and substrate respectively. In many cases perfect epitaxy
is not possible; therefore, the misfit between the coating and the

substrate has to be taken into account. It was shown that the adhesive

energy in the case of significant misfit is given by

E

ad “ (27t) 2 d

’ Ed

K G a

2

C3]

where E

d

is the dislocation energy per unit area. As a result of misfit

between athe substrate and the coating, strains will be produced so that

the equations for adhesion must be further modified. In the case of

significant stored energy, the adhesive energy is given as

where E

g is the strain energy. A special case was calculated for zinc

coatings on aluminum whose epitaxial relationahips were characterized

during this program.

(2)

Each year some investigations and development are conducted as

a back up to the Standard Reference Materials (SRM) program. This year

a new x-ray spectrometer was evaluated for the measurement of coating

thickness. This involved designing and testing specimen holders, and

determination of the measurement precision for various coatings. Computing

equipment used for the coating thickness measurements has been upgraded.

Also the density of some autocatalytic Ni-P alloy deposits was determined

with a new piece of equipment owned by the Density Measurement group at

(3) Work has continued under the sponsorship of the NBS Office of

Nondestructive Evaluation on the development of dye penetrant sensitivity

crack panels by electrodeposition. Alternate layers of nickel and

copper are electrodeposited on a nickel sheet so that a cross section of

the laminate electrodeposit shows thin copper lines between bands of

nickel. The copper is then partially dissolved leaving deep cracks.

Crack panels made this way can be used to evaluate an important NDE

crack detection method. A number of crack panels have been produced and

given to other laboratories for evaluation. Each panel is about 1/2 x 2-1/2 cm with four parallel cracks running the length of the panel. The

four cracks are nominally 0.2, 0.6, 1.0, and 2 pm in width and several

times deeper than wide. Similar crack panels will become SRM's when the

evaluation reports come in with recommendations relative to crack widths,

panel size, panel mounting, etc.

(4) A simple chemical immersion technique has been developed which

produces ultra-black surfaces on electroless nickel-phosphorus coatings.

A patent on this development was granted this year. The blackness is

associated with a unique surface morphology consisting of a dense array

of microscopic conical pores (2-9 pm average diameters) perpendicul ar to

the surface. This structure is produced by a selective etch with nitric

E ad =

(2n) 2 d

“ E

d

" E

s [4]

NBS.

mnnrwMMiHMrtHrHwiMiiroitwiiHiiiiiimmramtu
acid. The unique surface morphology, acting as light traps, is capable

of absorbing over 99 percent of the incident light when tested at wavelengths of light from 340 to 2140 nanometers. This extremely high

light-absorbing surface can be applied to a variety of substrates, such

as metals, ceramics, glass, and plastics.

Interest in this process over the past year is indicated by over

325 inquiries that have been answered for the application of this coating

in space telescopes, laser absorbers, radiometers, black body detectors,

solar collectors, low reflectance standards, etc. Four talks were

presented and four papers were published, as well as news briefs appearing

in trade journals, newspapers, and scientific magazines covering a broad

scope of interests from optics, solar energy, astronomy, and space

physics to materials and coatings research.

(5) Work continued in the production of coating thickness SRMs,

used to calibrate coating thickness gauges. A single SRM is a metal

coupon, 3 x 3 cm or 1 . 5 x 1 . 5 cm, one surface of which has an electroplated 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 made ranging

in thickness from 0.7 pm to 2 mm. (Gold coatings are actually certified

in units of mass/area, not length.) They are designed for use with

either magnetic type or beta backscatter type thickness gauges.

These SRMs are packaged in sets and the SRM catalog lists some 31

different sets. About 3000 individual coating thickness standards were

produced during FY79, and about 5000 were produced during FY80.

Chemical and Biodegradation Processes

Subtask 2 of Task 12111

F. E. Brinckman, W. P. Blair, R. H. Fish 1

, C. Freden2, W. P. Iverson,

J. A. Jackson, K. L. Jewett, R. B. Johannesen, G. J. Olson3

, and E. J. Parks

X NBS Guest Worker, December 1979

2 Part-time Student

3 NRC-NBS Postdoctoral Research Associate

The technical activity of this subtask is focused on measurement

and mechanistic characterization of chemical and biological processes

involved in the transformation and degradation of materials. Underlying

the multidisciplinary approach taken by the Group is the recognition

that both chemically and biologically mediated processes are significant

factors in corrosion and degradation of materials in natural service

environments. The current work in the task seeks to concentrate on a few topical problems of major importance involving metal -containing

materials. Emphasis is on assessing roles of organometal 1 i c substances

in materials transformations and degradation because of the widespread

use of organometal 1 ics in world technology and the significance of

organic derivatives in the degradation, mobilization, and transport of
metallic elements through the environment. The work in this subtask

falls into several areas with two primary foci: the development of

compound-specific methods for detecting, identifying, and quantitating

organometal species at environmental concentrations (pgL 1 to ngL 1 );

and the application of this methodology for characterization of the degradation of materials in service environments.

Speciation of Qrqanotin Monomers : The durability and environmental

impact of organotin materials are of current interest because of the

widespread use of these substances as anti foul ants, biocides, and polymer

stabilizers and recent demonstrations of their widespread occurrence in

the environment.

The speciation of R 3 Sn+

ions by high performance liquid chromatographic separation techniques using strong cation exchange (SCX) columns

coupled to tin-specific graphite furnace atomic absorption (GFAA) techniques, reported in FY78-79, has been expanded to include the tri cyclohexyl tin ion and separations have been improved to provide increased

column efficiencies and reduced elution times. An exten|ion of this

work to include speciation of more highly retained R2 Sn2 species (R =

butyl, phenyl, ethyl) has been developed. Moreover, the selectivity of

the SCX column is such that facile resolution of isomeric organotin

species was accomplished.

A major accomplishment in FY80 was the development of a quantitative relationship between the chromatographic behavior and molecular

substituent properties, derived from measurements physically independent

of chromatography, for several classes of organotin compounds. This

relationship permits: (1) accurate prediction of optimal chromatographic

conditions for known organotin ions, or (2) identification of unknown R groups on organotin compounds. After conducting analysis with various

molecular substituent constants in the literature, the constant selected

<D for

(<J

T

) this

and

was cr T

, which

dn resonance

represents combinations of both inductive

effects that may occur with energetically (V

study

p7i or available p or d orbitals in R-Sn bonding. The relationships

natural logarithm of the chromatographic capacity factor, k

1

, independent literature values of for the

is indicated in figure 1. Detection limits

respectively, for Bu 3 Sn

+ (r = 0.993), d 3 Sn+

(r = 0.979), were determined experimentally

Differences in detection limits for the various

due to the relative atomization efficiencies of

graphite furnace.

of the

versus

various classes

of 16 ng, 5 ng,

of organotins

and 26 ng,

(r = 0.997) and (Cyhx) 3 Sn

+ from calibration curves,

species were probably

each species in the

Application of this technique to a problem of environmental concern

provided significant information. At various naval dockyards, the

"spent" organotin (tri butyl tin) anti fouling coating on ships is removed

by grit blasting. This material (grits plus coating particles) which

still contains large amounts of organotin (R 3 Sn

+

) biocide presents a disposal problem. Direct examination of the water leachate of this

lUmUllllMHIMWBH IIMIIFHHI
material by the HPLC-GFAA system indicated the presence of both Bu 3 Sn

+

and the less toxic Bu2 Sn

2+ (about twice as much), the latter being a decomposition product of 8u3 Sn+

. These results are the first specific

demonstration of a decomposition pathway for tri butyl tin and clearly

suggest a valuable monitoring tool

.

Speciation of Qrqanotin Volatiles from the Chesapeake Bay : Several

organotin species, especially the methylated species, reported to be

present in natural waters and urine are believed to be biologically

produced from inorganic tin. The volatility of these materials permits

the use of gas chromatographic techniques. Last year, modifications

were made to a commercial flame photometric detector (FPD), which allowed

volatile tin species to be detected at pg levels. Samples of headspace

gas above bacterial cultures were analyzed and volatile tin metabolites

were detected. It was also desirable to analyze the presence of aqueous

samples to determine the presence of dissolved volatile tin species.

For this purpose, a purge and trap sampler was retro-fitted to the GC

system for use with the FPO. Developed for the Navy (ONR), this system

can be used aboard ships for on-site monitoring.

In the purge and trap sampler, an inert gas, He or N 2 , is purged

through the liquid sample to drive any dissolved volatile compounds from

the liquid into the headspace. The volatiles driven into the headspace

are collected at ambient temperature on a trap filled with Tenax GC, a polymer which retains the volatile species. The Tenax trap is quickly

heated to a high temperature to introduce the collected volatiles into

the gas chromatograph where they are separated on the column and detected

by the FPD. Methylated sulfur compounds (i.e. , dimethyldi sul fide and

methyl sul fide) are naturally occurring microbial metabolites found in sea water and could therefore interfere with the tin response since

sulfur can also be detected with the present FPD system. Tin calibration

curves for several interference filters were therefore made using standard solutions of Me4 Sn/Me 2 S and Me4 Sn/Me2 S 2 in deionized water and sea

water. Detection limits ranged from 30 to 50 ng/L. but will be improved

ten-fold with new photomultiplier and improved calibration techniques.

Field water samples collected from the Chesapeake Bay (Baltimore

Harbor) were analyzed for volatile organotin species using the Purge and

Trap/GC-FPD technique. Results of these analyses indicated the presence

of tetramethyltin in the Bay water. By using the method of additions,

as much as 900 ng/L of Me4 Sn may be detected in Colgate Creek in Baltimore

Harbor. Partition coefficient measurements of Me4 Sn will be necessary,

however, to determine the concentrations of Me4 Sn more accurately in

aqueous media.

Speciation of Arsenic Compounds in Oil Shale Process Waters : The extraction of shale oil from substantial deposits of oil shale has emerged as

a viable fossil fuel alternative. Current recovery procedures produce,

along with shale oil, considerable amounts of process waters which

contain many organic compounds as well as trace metals and metalloids in

forms that are potentially toxic to aquatic biota and man.
As part of a joint effort between Chemical and Biodegradation Processes Group personnel and members at Lawrence Berkeley Laboratory's Oil

Shale Program, a research program which seeks to characterize metal

toxicants present in various process waters of representative recovery

procedures was initiated. Compounds of arsenic were selected for study

because substantial concentrations of total arsenic (0.3 - 15.5 ppm) had

been measured in process waters, and some inorganic arsenic compounds

are suspected of being carcinogenic.

In the course of exchange visits between LBL and NBS, seven oil

shale process waters, including samples from simulated, true or modified

i n situ processes, were speciated for inorganic and organoarsenic com- pounds. High performance liquid chromatographs automatically coupled to

graphite furnace atomic absorption spectrometers were employed in both

laboratories. The molecular forms of arsenic contained at ppm levels in

these waters were identified for the first time and shown to contain

arsenate, methyl arsonic acid, and phenyl arsonic acid, figure 2. The

chromatograms for each process water studied have significant implications regarding those arsenic species found and those not and/or marginally detected (such as the possible carcinogen, arsenite), as well as quantifying future environmental impacts for such bioactive species

involved in oil shale retorting technology.

Size-Exclusion Characterization of Biocidal Qrqanotin Polymers : Organometallic polymers (OMP's) incorporating triorganotin varieties, chemically

bonded to carboxyl groups pendant along polymer chains are undergoing

intensive development as long-term controlled release, marine anti fouling

coatings. In use, organotin moieties are slowly leached out of the

coating to provide the fouling inhibition effect. To devise a useful

and predictable slow release QMP, it is desirable to incorporate most of

the organotin within a high polymer matrix.

Size exclusion chromatography coupled with tin specific graphite

furnace atomic absorption spectroscopy (SEC-GFAA) has been developed to

the point of characterizing high and low polymer fractions of OMP's.

Significant characteristics obtained include molecular weight average,

number average, molecular weights, molecular weight distribution, and

the percent of tin found in each of the major fractions. It has been

demonstrated that a large number of OMP's include 10 to 20 percent of

the total Sn in a low Mw fraction. The presence of the low Mw tincontaining species in these high concentrations is undesirable from the

point of view of controlling the rate of release of toxic moieties in

service environments. However, the nature of the material and its

source are uncertain. These materials could be unreacted tributyltin

methacrylate (TBTN), unconverted tributyltin oxide (TBTO), or decomposition fragments.

In addition to these studies on the developed OMP's an investigation

of the kinetics occurring during the copolymerization (methyl methacrylates and organoti n-substituted methracyl ates ) of these materials by

both SEC-GFAA and FT-NMR of the Sn nucleus has been initiated (figure 3, 4).

This is the first metal -speci fic use of the NBS Hi -Field FT-NMR facility.
Evidence indicates that the signals from the monomer and polymer are

well separated so that kinetic information, not previously obtainable

with studies of the H nucleus, can now be obtained.

Microbial Volatilization of Mercury by Thiobacillus Ferrooxidans : In

the mercury geochemical cycle, mercury is found principally as the

sulfide ore, cinnabar(HgS) and is believed to be trapped in polluted

bodies of water as the sulfide. Although it has been suggested that

mercury can be released from sulfide by biological action, there is no reported evidence of this process. Since a bacterium, Thiobaci 1 1 us ferrooxidans has been repeatedly demonstrated to solubilize metals from

their sulfide ores, this organism would also appear as the logical

choice for its capacity to solubilize mercury from such ores.

ferrooxidans is an economically important iron and sulfuroxidizing, acidophilic bacterium which contributes to the production of

acid coal mine wastes by the production of sulfuric acid through the

oxidation of iron pyrite (FeS2 ) and other metal sulfides. Conversely,

its highly beneficial' activities involve the leaching of many metals

from their sulfide ores. Little is known of the action of T. ferrooxidans

on mercury, however, despite the fact that mercury often occurs associated

with coal and metal ore deposits containing mercury.

In investigating the effect of mercury on T. ferrooxidans , it was

found that populations of this organism, normally quite mercury sensitive, readily develop tolerance to Hg

2+ ions, and, furthermore, have

associated with this tolerance the capacity to volatilize the Hg

2+ ions

by reduction to elemental mercury (figure 5). This is the first demonstration that autotrophic bacteria can bring about this reaction, although

it is quite common in heterotrophic bacteria. Mercury volatilized in

the latter group of bacteria is usually plasmid (extrachromosomal QNA)

mediated. Preliminary evidence has, however, failed to indicate any

plasmid DNA in this organism.

Microbial Tolerance and Uptake of Qrqanotin Biocides : The use of organotin compounds as anti fouling agents in coatings for marine use is expected

to increase. Since it has been demonstrated (above sections on speciation)

that the highly toxic tributyl tin moiety is leached from an organotin

polymeric coating, it is of concern from an environmental standpoint to

determine the fate of such a compound in biological systems (i.e.,

conversion to a more or less toxic moiety or sorption which may be

physically, chemically or biologically mediated).

Six naturally organotin (tributyl tin) resistant bacterial strains

obtained from Dr. R. Colwell (University of Maryland), (isolated from

the Chesapeake Bay and Newport Bay, California sediments) were grown in

the presence of 10 ppm of tributyltin chloride in a low sulfur medium.

Analysis of the cell -free medium by the HPLC-GFAA tin specific system

after various periods of time showed no evidence of tributyltin degradation (i.e., no other tin moieties could be detected). Analysis of the

cell -free medium by the Purge and trap/GC-FPD has, however, indicated

the presence of a volatile tin species.
In studies with the six organisms, it was found that the cells

accumulated significant amounts of tributyltin (c. , 0.6 to 2.2 percent

of the total organotin present in the medium). Studies are in progress

to determine whether the tin uptake is simple sorption or whether it is

biologically mediated.

Stability Testing of NBS SRM's : A project concerned with the establishment, of a measurement protocol which permits quantitative assessment of

the nature and extent of their biodeterioration potential under present

NBS certification procedures, was initiated. This project will be

sponsored by the current and future NBS programs. With respect to

potential biodegradation, results have indicated that the SMR's may be

divided into three categories:

(1) sterile as received [viz., oyster tissue (SRM 1566), river

sediment (SRM 1645), orchard leaves (SRM 1571), and brewers yeast (SRM

1569)];

(2) sterile as received but contaminated by recommended handling

procedures [viz., freeze-dried urine (SRM 2672)];

(3) not sterile [i.e., urban particulate (SRM 1648)].

Brewers yeast, oyster tissue, and orchard leaves exposed for a total of

three and one-half hours at one-half hour intervals to the outside air

and maintained at 25 °C, 90 percent relative humidity, became badly

deteriorated, largely as a result of fungal attack.

Biomethyl ation of Inorganic Tin : It has been previously reported by NBS

(C. Huey, F. E. Brmckman, S. Grim, and W. P. Iverson; Proc. Inter.

Conf. on Transport of Persistant Chemicals in Aquatic Systems 1974) that

a volatile methylated tin species was produced by a Pseudomonas strain

(#244) from the Chesapeake Bay. Re-examination of the headspace from

this culture growing in the presence of Sn

4+

, using a GC-MS system,

revealed the presence of two methylated tin species, one presumably

tetramethyl tin and the other possibly trimethyl stannane , Me 3 SnH.

Anaerobic Corrosion of Iron : Anaerobic corrosion of iron occurs through

out the world and from an economic standpoint, is quite costly. Sulfate

reducing bacteria, primarily of the genus Desul fovibrio , are responsible

for this type of corrosion. It has been postulated that corrosion by

these bacteria is caused by their removal of hydrogen from the surface

of iron, causing the iron to go into solution.

Evidence was obtained which indicated that this mechanism may not

be responsible for the main corrosive effect of these organisms. Corrosion by these bacteria has been demonstrated to be caused by a volatile

sulfur containing metabolic product which is not H 2 S. Evidence for at

least four sulfur containing metabolites from this organism has also

been demonstrated.
Acetate

Figure 1. Linear relationship between the substituent constant a for

R groups on various organotin in two buffered solutions

(citrate and acetate) and the logarithm of the observed

capacity factor k

1 . Anomalous behavior for triphenyltin is

apparent in both buffers. Indicated in the lower plots ar t-0u, i-{3u, and n-£u (descending order) in two citrate buf

concentrations, and Ar = to 1 y 1 ; para-tolyl ; and benzyl

(descending order) in three citrate buffer concentrati ons

.

(0.005 M, 0.0075 M, and 0.01 M, right to left).

O)

'I—
@-As(OH),

Std

AsO3-

Me2AsOH

0

MeAs(OH),

AsO

li n i i Mm mill i i ii 1 1 'TIT I |

I 1 l Oxy Heater -Treater Water (1= 50 dilution)

Figure 2. Element-specific chromatograms or arsenic species fingerprints

obtained by HPLC-GFAA (bottom of each sample set) and associated

UV detector chromatogram (continuous trace shown at top,

inverted) are compared against standards for three water samples

taken at different stages of the Occidental Modified l£ Situ

Process, Retort 5, Logan Wash, Colorado.

42
SEC-UV-GFAA CHROMATOGRAMS OF AN

OMP AT TWO STAGES OF REACTION

t 1 1 1 r

10 30 50

V

'

, m L

R

Figure 3. The changes in UV ana 3n spectra are followed initially and

after 24 hours; during the conversion of tributyl tin methacry!

in the presence of methl methacry! ate ana a free radical initia

The ratio of high (low retention volume [V']) to low (high

i\ [Vjjj]) molecular weight species increases with rescect to time.
FT-NMR 119Sn SPECTRA OF AN OMP

AT TWO STAGES OF REACTION

f 60 30 0

6 , PPM

Figure 4. Changes in FT-NMR 119 Sn spectra during the same reaction as shown in figure 3.

44
Hg

,

ng

mL

32

0 40 80 120 160

HOURS

Figure 5. Formation of elemental mercury from Hg 2 by the autotrophic

Bacterium Thiobacillus Ferooxidans . The bottom curves indicate

the response of the mercury unadapted sultures ( —• — ) and

the organism free control ( —0 —). The top curves show the

responses of the mercury adapted culture (0.6 ppm Hg 2 ');

four separate experiments.
>1
HIGH TEMPERATURE CHEMICAL STABILITY OF MATERIALS FOR PROCESSING ANO

SERVICE

Task 12112

The objectives of this task are to provide measurement methodology,

test methods, and data related to chemical durability, performance, and

processing of materials in high temperature service environments, as well as methodology for prediction of long-term performance in those

environments.

The technical activities fall into two subtask areas. One subtask

emphasizes heterogeneous processes involving interactions of materials

with agressive (usually gaseous) high temperature environments. The

other subtask emphasizes solid-state structural considerations and mass

and charge-transport processes in high- temperature solids.

High Temperature Processes

Subtask 1 of Task 12112

J. W. Hastie, D. W. Bonne!! , L. H. Grabner, W. S. Horton, E. R. Plante,

P. K. Schenck, A. B. Sessoms, A. Chakrabarti 1

^•Guest Worker

Technical activities in this- subtask are aimed at developing molecular specific experimental methodology and theoretical modeling tools to

characterize the interactions of materials with aggressive gaseous high

temperature service environments. Such characterization is critical for

performance predictions in new high technology applications (coal -combustion

and conversion, advanced propulsion systems) and for materials processing

at high temperatures (chemical vapor deposited coatings, metallurgical,

and ceramic processing). Similar activities focus on the chemistry of

combustion modification, e.g. , by inorganic flame inhibiting additives.

Vaporization, and Chemical Transport in High Temperature Vapors : In

this activity, new or improved measurement technigues are developed and

applied to the study of the reactions, performance, and durability of

slag and ceramic materials in high- temperature process environments,

such as those pertinent to the operation of coal gasifier and magnetohydrodynamic (MHD) plants. Problems of immediate concern include:

(1) development of improved methods for identification and guantitative measurement of gas and vapor species in heterogeneous systems

at high temperatures and pressures;

(2) defining experimentally and theoretically (through thermodynamic

modeling) the degree of alkali seed retention by coal slag under MHD

conditions

;

(3) determining the durability of candidate ceramic MHD electrode

and coal gasifier components with respect to their possible degradation

by vaporization and chemical transport in MHD and coal gasifier atmospheres;

47
(4) obtaining molecular data on the rates and mechanisms of the

release of alkali and other inorganic impurities from coal minerals,

slags and fly ash, pertinent to gas clean-up technology in advanced

multicycle combustion systems; and

(5) defining the mechanistic action of inorganic additives as flame

inhibitors and enhancers.

Progress in these problem areas during FY80 is summarized in the

following items.

Item (1) The recent development of Transpiration Mass Spectrometry

(TMS) has provided a new tool with applications beyond the original

application to thermodynamic studies of vapor transport. Supersonic

expansion to the low pressure required in the spectrometer results in

considerable cooling. The translational temperature in the beam may

drop by a factor between 5 and 100. Typically, rotational motions

equilibrate rapidly with translation. For diatomic molecules vibrations

may relax to within 10 percent of the translational temperature.

One effect of the increased population of low rotational levels of

molecules is the marked increase in intensity of the rotational spectra.

For diatomic molecules, this enhancement is proportional to T

2

. Without

a detailed analysis of spectra from high temperature molecules a correct

description of their structure and derived thermodynamic functions can

be grossly in error. Such errors limit the utility of modeling in

combustion, magnetohydrodynamic generation of energy, and other high

temperature processes. Consequently, in conjunction with the Center for

Thermodynamics and Molecular Science, a Stark-modulated microwave absorption cell has been coupled to the Transpiration Mass Spectrometer to

obtain structures for high temperature species. The near room- temperature

gas molecules, CH 3 CN and CH 3 F, of known structure were used to investigate

beam formation and system behavior. Experiments on the high temperature

test molecule, NaCl , were initiated but cooled detectors and signal

averaging will be required to produce useful signals.

The "spectroscopically cool" beam source also allows investigation

of the recently identified effect of temperature dependent electron

impact fragmentation. Fragmentation, which is the splitting of a molecule or ion into smaller units, can lead to misinterpretation of mass spectrometric data if not properly understood. Since the ratio of

ion fragments to ion parents is governed by Franck-Condon type transitions

between ground state and bound or repulsive ion states, vibrational

population shifts can in theory cause significant changes in this ratio.

Our earlier work on NaCl beams showed a major temperature dependence in

the Na

+ /NaCl+ ratio which has been tentatively identified as due to this

effect. CsCl is a molecule for which the temperature dependent fragmentation effect has been reported at high temperatures. Under the influ- ence of beam cooling by a factor of five the effect is exaggerated,

exhibiting CsVcsCl'

1" ratios several times larger than the reported high

temperature value. Furthermore, the expected strong temperature trend

has been found. Further work in this area is being pursued.

48
Item (2) Current studies in MHO seed-slag vaporization focus on K2 0

activity determination in model four-component slags containing K2 Q,

CaO, A1 2 0 3 and Si02

. Knudsen effusion mass spectrometry is used in this

effort. These results are needed to provide a data base for construction

of a theoretical /empirical thermodynamically consistent model for prediction

of alkali seed retention and/or corrosion properties of real slags

produced by combustion of Western sub-bituminous coals. Measurements

completed during the current year have demonstrated that Si02 and A1 2 0 3

have a synergistic effect in reducing K2 0 activity while confirming that

addition of CaO increases the K2 0 activity by orders of magnitude. The

NBS-measured activities for K2 Q in various slag- like melts are used by

many other scientists as reference data.

Vaporization measurements for systems where NaCl was added to

K2 0-containing slags showed a rapid exchange between NaCl and K2 0 according

to the reaction:

2 NaCl + K2 0 (dissolved in slag) = 2 KC1 + Na2 0 (dissolved in slag)

at temperatures as low as 800 K. Sodium and potassium chloride vapor

species as well as mixed halide species were observed. These measurements

and observations suggest that this process, or one involving other cheap

mass produced salts (such as CaCl 2 ), could form the basis of a process

for economic recovery or production of the more valuable and costly

potassium salts from MHO slags or high potassia (8 wt. %) clay minerals.

Chemical thermodynamic data predict large negative free energy changes

for these reactions.

Earlier NBS data for potassium vapor pressure over K2 0-SiQ2 melts

were fitted to equations which extrapolate properly as required by the

Gibbs-Duhem Law. These equations were also constrained to give the

NBS-preferred value of the potassium and oxygen vapor pressures over

molten pure K2 0. The finally chosen fitted equation reproduces the

experimental pressures with a standard error of 13 percent. "Regular11 and "non-regular" solution effects were included as well as their temperature coefficients. Beside this empirical fitting, these K2 0-Si02 solutions

have been modeled by assuming the formation of ideal solutions with

compound formation, as has been done by others who claim success. If

the presence of only K2 SiQ 3 is assumed, there is approximate agreement

over a limited temperature and concentration region with the experimental

data quoted above. However, if K2 Si 2 0 5 is also included, the results

diverge from experiment by two orders of magnitude. Logically, the

model is incomplete without the inclusion of another known compound,

K2 Si 4 09 . It is evident that the inclusion of this compound would make

the comparison even worse, and that this model has severe logical drawbacks

and should be discarded.

Item (3) A slightly modified version of the NASA Chemical Equilibrium

Calculations computer program has been received and put into operation.

Accompanying this was a much larger thermodynamic data bank, which con- tains 871 species instead of the former numbei—458. Also 120 species

had been updated. SOLGASMIX, our copy of the University of UrneS (Eriksson)

computer program for heterogeneous simultaneous equilibria, has been

49
• K. 0-Si02 > slag-hydrogen-v<ater

nredictions in W . 2 this orogram has

a’SiW - — ts

also been obtained and should

mine ral components

Item C« A -ailed

—

al

« £«

Vapor*" transport jevalopment

r of ^ gnvironmenta^pol^b^'' 00 "

The coal -bearing mineral

q

1 with proportions simila t

S02 , c0

5i0„ A1,0„ KjO. and PH®*, indicated the^re lea ^ „

siir“-v,‘, c S str.ss- sv -,’S.r ~‘S'”/’"

SS^v>!k’r“i»:S'

nTM

of SiO* and Fe0 We

transport were noted using the TM

increases m

u n on iVlite vapor transp

, the presence of H2 sm

. but, in

srii' 4-ir.ss.ss.u3

brium for additiono

dJ attention^ Of »P

t0 water vapor because

KMS measurements wnic ^

sUgs when expose

inability to

_ of kinetic effects. . . w ith Division ooo>

Item CS) m a &

thermodynamic

-clafsicll

prediction

tr^l^ Ta®^^

thi S molecule P y several

expected^in S^^^^^volvedi^these" resul ts^show that equi^br^um is^n^^

sss r.^fee r^s^s: . - - —

vaporiiati on

6

from slags.

West Virginia (U«)

Item (6) in

^

^nlc^^^e Ul

and the —9*fJ"and potassium bantoate were 'nv ^.9^ gf

^ decompo—

compounds so^

m

da

" omposition Pf°c

.essntf4st as models of the ash/am

products

6

of these

a5Sff»T»,5!sa?-*

on

50
ij Prior to the TMS studies, thermogravimetric analysis (TGA) studies

at UWV had identified the presence of two distinct processes in the

inert gas decomposition of the alkali benzoates. With oCOQNa at ~ 450 °C

a sharp weight loss occurred and persisted until ^ 550 °C where weight

I loss ceased. At 775 °C, a new sharp weight loss region was encountered,

which terminated at 925 °C. The TMS study led to identification of the

species evolved in each of the two regions and the combined vapor pressure versus temperature curves were in good agreement with the TGA data.

The first region was assigned as simple decomposition of the benzoate,

the major mass spectral ions being C6H6 + and C02 +

. Hence the condensed

phase decomposition reaction releases benzene and C0 2 leaving Na2 C0 3 (s)

and carbon as a char. The second region showed a rapid rise in C0

+ and

Na+ mass spectral signals, indicating the condensed phase reaction:

i Na2 C0 3 (c) + 2C(char) = 2Na(g) + 3C0(g).

f Item (7) The mechanistic action of phosphorus and halogen-containing

additives in flame inhibition and promotion was determined using mass and optical spectrscopic methods. Mass spectrometric measurements of

H-atom and other species concentration profiles were made on a near- stoichimetric, premixed, laminar H2 -02 -N2 flame containing CF 3 Br. The

results support

H2 + Br -> HBr + H

as a dominant flame promoting reaction. The effect of HBr on the temperature profile was previously determined using laser Raman spectroscopic

methods. Under inhibition conditions, i.e., observed reduction in

burning velocity, at a concentration of only 0.005 mole fraction this

compound reduced the clean flame reaction zone temperature by as much as 900 K (due to a downstream shift in the reaction zone). On the other

hand, a small increase in temperature occurred in the burnt gas region.

These effects are consistent with removal of H- atoms in the preflame and

reaction zone regions, resulting in a delay of the chain branching

process:

H + 0 2 = OH + 0.

- Virtually nothing is known about the high temperature chemistry of

phosphorus in a flame environment. Phosphorus compounds are known flame

retardants although the mechanistic evidence is empirical. High pressure

sampling mass spectrometry and optical spectroscopic methods have been

applied to the molecular characterization of P-ccntaining flames. The

species HP02 has been identified and found to participate in the key

processes controlling flame inhibition and enhancement. The important

reactions (forward and reverse) are predicted to be

HP0 2 + H t h2 0 + P0.

Inhibition occurs for cool flames when the left to right reaction predominates, whereas the reverse reaction, which predominates in hotter

flames, causes enhancement. This concept was elucidated from the deteri

31

I
mined H atom concentrations as a function of temperature and position in

the flame. The predicted inhibition enhancement cross-over point of

2350 ± 50 K is in good agreement with the experimental data for a wide

variety of flames. It was necessary in the course of this work to

estimate the structures and thermodynamic properties of HPO, HP0 2)

NaP02 , and Li P0 2

. The latter two species are significant in the determination of H-atom concentrations using the established Na/li spectroscopic

method. When formation of these species was taken into account good

agreement between measured and calculated H-atom concentration data was obtained in the equilibrium (burnt gas) part of the flame.

Characterization Methodology for High Temperature Gaseous Service Environments : Objectives of this activity are to develop and optimize measurement

techniques for characterizing high temperature gaseous environments,

including flames, and to apply the methodology to assessing and predicting the performance of materials in those envi ronments. During

fiscal year 1980 major emphasis has been in development of improved com- bustion diagnostic techniques and their application to elucidating mechanisms of combustion modification, including flame and smoke retardance.

The role of excited state atoms in both flame ionization and flame

chemistry is important, and the use of lasers to alter the excited state

population in a flame has become an important combustion probe. In

conjunction with the Center for Fire Research, this probe is being used

to determine the relative role of neutral atoms versus ions in smoke and

.particulate formation in an alkali seeded flame. The increased thermal

ionization of laser excited atoms (the optogalvanic effect) is used to

alter the neutral/ion ratio while a simultaneous scattering experiment

measures effects on particulate formation. This uncompleted work is

continuing.

In conjunction with the Center for Analytical Chemistry, modeling

and additional experiments have been done to study the collection mechanism

of ions and electrons from laser enhanced ionization in analytical

burners. The results of these experiments have been the determination

of effective ionization rates, the mobility of ions in flames, and

improvements in probe geometry to assure 100 percent collection of ions

formed by laser enhanced ionization. These experiments have shown that

even during short laser pulses it is possible to have partial thermalization of the laser excited atoms to even higher energy levels than produced

by the laser. The result is a 100- to 200- fold increase in the effective

ionization rate for the laser excited level. From an analysis of the

response time for the collection of the ions in a flame irradiated by a sharp laser pulse one can determine ion mobilities in the flame environment.

In order to study the efficiency of the collection of the ions/

electrons produced by laser enhanced ionization, a new technique for

imaging the ionization rates in flames was developed. In this technique

the burner is placed between two plates which are held at a high enough

voltage difference to collect the ions/electrons on a time scale faster

52
than diffusion, flame drift, or any other factor which would blur the

ionization image. A narrow probe, isolated electrically from the plates,

is moved along one plate to intercept the flow of electrons/ions locally

to the plate. The signal from the probe is then the ionization image as the probe is moved. The probe is about 95 percent efficient in selectively

intercepting the current flow from the flame and has about a 1 mm resolution.

These experiments are important in designing probes in analytical applications

which maximize sensitivity without increasing electrical noise. Since

metal atoms, particularly alkalis, are common contaminants in coal slag

and increase high temperature corrosion as well as play a role in particulate

(pollution) formation, increased sensitivity is important. This increased

sensitivity can only be gained with better knowledge of the formation

and collection mechanisms pertinent to laser-enhanced ionization.

Recent reports in the literature on laser induced changes in the

rates for alkali hydride and alkali hydroxide formation show that excited

state chemistry as well as ionization may play a role in laser/flame

experiments. In order to sort out the relative roles of excited state

ionization and chemistry in alkali seeded flames, experiments are planned

to couple the laser to the High Pressure Sampling Mass Spectrometer

system for simultaneous mass spectroscopic measurements. By monitoring

the influence of laser excitation on both the ionization and alkali

hydride/hydroxide formation simultaneously, the role of the excited

state atoms in both ionization and chemistry should be determined.

The chemical study of flames and flame inhibitors requires careful

measurement of temperature at specific points in the flame and the

concentration of species at these points. Because of the chemical

kinetics and equilibria involved, the concentrations are related to the

temperature by coupled exponential expressions. Consequently very

accurate temperature measurements are required. Two spectroscopic

methods are being studied: sodium 0-line reversal and hydroxyl radical,

OH, concentration by absorption. The hydroxyl radical method requires

use of the oscillator strength for OH, a commonly used value from the

literature. This value has been found to be in error due to omission of

vibration-rotation interaction leading to an error by as much as 25 percent

in OH concentration. This correction will be useful in future calculations of species concentrations.

Many of our flame studies involve a flame boundary. This may be

between clean flame and doped flame or shielding gas (N2 or Ar) and

flame. A major effort went into determining boundary layer effects.

The boundary layer region has a large concentration gradient because of

reaction of species with greatly different concentrations on either side

of the layer. As a consequence of this, different methods of 1 ine-of-sight

temperature measurement give different results. These differences have

been reconciled and corrections may now be made.

53
Thermophysical Properties of Solid and Liquid Tungsten : Tungsten is an important commercial material because of its refractory nature which

permits its being heated to a very high temperature without damage in an inert atmosphere. The melting point has been estimated to be 3630 K. Because of the difficulty of handling tungsten at such high temperatures

most of the thermodynamic and physical properties, in the region of the

melting point, are estimates. An attractive method for determining

enthalpies of refractory, electrically conducting materials utilizes

high frequency levitation and heating. For a dense material like tungsten

this could present problems which may be more readily solved by conducting

the experiments in space. NASA's program for Materials Processing in

Space includes research to test process concepts on the ground that may

be carried out in space. Such ground experiments conceivably could turn

out to be sufficient. As a result a joint effort has been undertaken by

NBS, Rice University, and the General Electric Company Advanced Applications

Laboratory to measure tungsten enthalpies by this method, levitation

calorimetry. Although the experiment is conducted physically at the GE

installation, NBS has been asked to participate in the design and con- duction of the experiments.

During the past year the calorimetric system has been made fully

operational to design specifications, the major problems in the pyrometric

measurement of sample temperature have been isolated, and these methodologies

are now’ considered adequate to the task. The levitation capability

problem has become the remaining serious obstacle.

Solid-State Transport and Stability

Subtask 2 of Task 12112

A. D. Franklin, C. K. Chiang, H. J. deBruin 1

, A. L. Dragoo, J. R. Bethi

2

1 Guest Worker

Postdoctoral Fellow

The Solid State Transport and Stability subtask is concerned with

the general area of ionic mobility in ceramic and other ionic solids.

The emphasis is on understanding the underlying processes and developing

techniques for identifying and studying them and for monitoring materials

performance in service. Experimental tools include not only ionic con- ductivity, but also other means of observing the position and motion of

ions in crystals, such as dielectric relaxation, electron spin resonance,

and anelastic relaxation.

Current focus is on solid electrolytes, with attention to two

important aspects. One is the nature of the charge transport process

itself, in the crystal lattice and across interfaces such as the grain

boundaries and at the el ectrode-el ectrolyte interface. It is desirable

in practice, for maximum efficiency, to minimize the resistance of a solid electrolyte device, such as a fuel cell or battery, including that

arising at the interfaces. Lifetime of the device depends on the stability

with resoect to processes allowing this resistance to rise in service.

At present no good technique exists for separately measuring these

54
various contributions to the resistance, nor are the factors controlling

the interface resistance at all understood. The other important aspect

concerns directly the long-term stability of solid electrolytes with

respect to such processes as defect clustering, order-disorder crystal

structure transformations, and dopant- ion drift under steady electric

fields. These are processes expected to influence the crystal lattice

resistance and therefore to contribute to degradation of the desirable

properties in service. Data on these changes and their rates in the

fluorite-structure oxides are needed in assessing the potential of these

materials as electrolytes in fuel cells and other devices.

The work is of direct interest to several industry groups using

solid electrolytes in their products and processes. The technologies

involved include fuel cells for utility power generation and transportation motive power; high energy density batteries for transportation

applications; gas sampling probes for industrial and automobile process

monitoring and control, and for air pollution monitoring; and research

instrumentation for gas composition control and measurement. In this

regard, we are participating in the National Fuel Cell Program jointly

operated by the Department of Energy and the Electric Power Research

Institute. In a more indirect fashion, the techniques we are investigating for grain boundary studies may be useful in following the kinetics

of sintering and grain growth in general, and as such should have wide

application to the ceramic industry. They should also yield information

concerning electron-hole recombination effects at grain boundaries in

semiconductors, and may prove useful in that industry also. Finally,

the work is directed toward identifying the basic atomistic processes

governing the ionic transport in the lattice and across grain boundaries

and interfaces, in terms of defect models and the influence of impurities

and defect clustering and ordering-. The models and techniques developed

are expected to further the science of ionic conduction and mass transport

in ceramics in a more general way.

The list of materials under study has expanded during this past

year. We continue to be concerned with grain-boundary and order-disorder

effects in Y-doped Ce02 , and related fl uorite-structure oxygen- ion

conductors such as stablized Zr02

. We are also studying Sr-doped LaCr0 3

and YCr0 3 , ceramics which exhibit mixed ionic/electronic conduction,

depending on dopant concentration, and which may find application as high-temperature electronic conductors in fuel cells and MHD channels.

Finally, we have found in polyacetylene, a conducting polymer, an interesting material upon which to test ways to extract information about

interfacial transport processes from the frequency dispersion of the

impedance. We are collaborating with Dr. R. A. Snell grove of the General

Refractories Company in the work on LaCr0 3 , and are indebted to him for

the materials. We also gratefully acknowledge the provision of YCr0 3 samples by Dr. T. Negas and Mr. W. Hosier of Division 565, the provision

of magnesi um-stabi 1 zed Zr0 2 specimens quenched from both the solid-solution

and the precipitation regions of the phase diagram by Professor Arthur

Heuer of Case Western Reserve University, and of polyacetylene samples

by Professor A. Heeger of the University of Pennsylvania.
Nature of the Charge Transport Process : The dispersion of the impedance

of polycrystall ine conductors (with respect to the frequency of the

measuring signal) contains information about charge transport in the

interior of the grains, at grain boundaries and other inhomogeneities,

and at the interfaces with electrodes. A major theme of the current

work is to learn how to extract this information from the data on the

frequency dependence of the impedance. In previous work we developed

an equivalent circuit to describe the impedance data for Y-doped Ce02

ceramics over the frequency range from about 50 Hz to about 13 MHz. A

major problem encountered with this approach is that one must select a priori the model to fit, and it is not always clear what the correct

model is. Figure 1, for instance, shows the results of attempts to fit our standard equivalent circuit, shown as an inset in the figure, to

data on Y-doped Ce0 2

. The grain, boundary impedance Zg

b was represented

by a Cole-Cole distribution of time constants (K. S. Cole and R. H. Cole, J. Chem. Phys. 9, 341 [1941]), and the electrode impedance Z -j by

a simple 1 i near law

5

Z

el = A/(ju.T)

n

where A, x, and n are adjustable parameters, n lying between 0 and 1,

j = -/-T , and uj is the circular frequency. The discrepancy between

calculated and observed points in figure 1 is persistent and not a result of fitting errors. It makes convergence of the least-squares

computer fitting routine very difficult. It seems probable that it

arises from the choice of the Cole-Cole distribution, and we plan to

explore other distributions in the future. In order to understand how

the details of these distributions influence the impedance data, we have

also been exploring the impedance values calculated on the basis of

model equivalent circuits using various distributions, for comparison to

actual data.

It appears possible, with our rather wide range of frequencies, to

perform an analysis that is considerably less model -dependent. This

technique, described with reference to dielectric measurements by Mi sell

and Sheppard (J. Phys. D: Appl. Phys. 6, 379 [1973]), treats the impedance

as arising from a series array of parallel R-C circuits with an unknown

distribution of time constants. By suitable mathematical deconvolution

techniques this distribution of time constants can be obtained from the

frequency dependence of either the real or the imaginary part of the

impedance. With our computer-controlled data-gathering facility it is

quite feasible to obtain data at 100 or more frequencies distributed

evenly in log frequency space, very much facilitating the computations.

Successful transformations of this kind have been obtained, but the

resolution is not yet satisfactory, and work in the future will be aimed

at improving it.

Previous work revealed important differences in the component of

the impedance ascribed to the grain boundaries in specimens of Y-dooed

Ca0 2 prepared in rather different ways. Current work is continuing with

studies of the influence of specimen annealing on this component. We

nope also to enlist the aid of the new STEM being installed in Division
in searching for compositional and structural differences. We have

also obtained (courtesy of Dr. Roy Rice, Naval Research Laboratory) a number of large specimens of Y-doped Zr02 , with properties similar (but

not identical) to the Y-doped Ce02 , containing only a few large crystallites and grain boundaries. We hope to do direct and fundamental experiments on these grain boundaries to correlate changes in impedance with

changes in the grain boundaries.

Inhomogeneities other than grain-boundaries can also contribute to

the impedance. Magnesium-stabilized zirconia, Zr02 containing about

eight mole percent MgO, is metastable in the highly oxygen-conducting

fluorite phase below about 1700 °C. We have compared the impedance of

otherwise identical specimens annealed (1) above this temperature, in

the single-phase fluorite-structure solid solution region of the phase

diagram, and (2) below, in the two-phase region in which we expect precipitation of tetragonal -structure Zr02 particles in an MgO-rich matrix.

We find that the precipitation anneal does result in the appearance of

an additional contribution to the impedance, as shown in figure 2.

In this figure, the additional contribution is shown in the inset, and

has all the appearance of a series distribution of parallel R-C networks

with a somewhat broadened distribution of time constants.

The impedance can also reveal information about the electrode/electrolyt

interface. This interface for Sr-doped LaCr0 3 ceramic with sputtered Au

or Pt electrodes has shown a strong, and surprising, sensitivity to the

oxygen activity at low temperatures, down at least to the neighborhood

of room temperature. Figure 3 shows this dependence at 52 °C. When a specimen previously equilibrated with 0 2 at one atmosphere (0.1 MPa)

pressure was exposed to tank N2 (P02 ~ 10 5 MPa) an increase occurred in

the contact resistance by almost two orders of magnitude. This change

in resistance was reversible, the resistance changing back to its lower

value when the N 2 was replaced by 02

. These changes appear to be compatible

with a model in which compensation for the dopant Sr ions in the surface

is primarily by oxygen vacancies whereas in the bulk it is primarily by

electronic holes, and the oxygen vacancy concentration (state of reduction)

follows the atmospheric oxygen activity by a diffusion process. Since

only a thin surface layer (we estimate about 10 7 m) is involved, the

chemical diffusion coefficient for oxygen is not hoDelessly large (^

10 16 cm2 /sec). Similar effects have been seen in the grain boundary

impedance of Ca-doped YCr0 3 , and this difference in behavior between the

surface, both intergranular and exterior, and the grain interior may be

a general feature of these perovski te-structure chromites.

Polyacetylene is a polymer film representing a very different

structure. There are no "grains" and "grain boundaries" as such, but

instead there are fibers or crystalline regions composed of bundles of

polymer chains, along which electronic charge carriers can move with

relative ease. The transport of cnarge from one chain to another, and

even more from one fiber to another, must represent a more difficult

process, so that interchain or interfiber contacts may be expected to
behave electrically like grain boundaries in ceramics. We find indeed

that the impedance reflects the presence of such electrical barriers or inhomogeneities. We find, furthermore, that doping of the polymer with

oxygen has a strong effect on the intrinsic, interchain resistivity, no effect on the geometric capacitance, and only a small effect, if any at

all, on the inhomogeneity impedance. This is satisfying, since it

accords with the generally accepted notion that doping of polyacetylene

affects primarily the number of charge carriers. The fact that the

doping qualitatively affects the electrode resistance and capacitance as one would expect for changes in charge carrier concentration at a barrier

arising from some sort of depletion layer is also in accord with this

view of the doping process.

Long-Term Stability of Solid Electrolytes : The basic transport process

in ionic conductors is carried on by lattice defects, oxygen vacancies

in the case of the doped Ce02 we are studying. In materials whose

conductivity is high enough to be of technological interest, the dopant

ion and vacancy concentrations are so high that association among these

defects plays a major role in determining the transport properties.

This aspect of our work is concerned with elucidating these associations

and their interactions with the transport process. We are approaching

this problem from both ends of the concentration range, the high end

where association will lead to ordered phases and order-disorder transformations, and the low where discrete clusters or complexes of a few

defects can be detected.

The stimulation of an order-disorder transformation can be done by

long-time anneals, over a range of temperatures and compositions to map

the effect on the phase diagram. The furnaces and controls for such

long-term anneals have been completed, and some, but not all, of the

specimens prepared for a study of the effect of long-term (at least 32

weeks at temperature) anneals on the intrinsic and grain-boundary impedance

of Y-doped and Gd-doped Ce0 2 as a function of the cation ratio of dopant

to Ce (values of 10/90, 20/80, and 30/70 have been chosen for study) and

as a function of temperature (from about 500 °C to about 1200 °C).

The preparation of materials worthy of study has occupied considerable

time. A technique of homogeneous precipitation has been worked out for

preparing mixed oxide powders of R 2 0s and Ce0 2 , where R = yttrium or a rare earth. With the resulting powders, ceramics over 95-97 percent

dense have been prepared by thermal sintering, and over 99.5 percent

dense by hot pressing. These ceramics exhibited very sharp x-ray diffraction patterns and quite narrow distributions of grain size. Specimens

containing Y at the 10/90 composition are available. A commercial

laboratory is preparing the others (Y at 20/80 and 30/70, Gd at 10/90

and 20/80), and has prepared the powders but has not completed the

hot-pressi ng.

58
In order to assay the compositions in terms of major components,

x-ray fluorescence will be used. Work on preparing standards (dissolved

in Li 2 B 4 07 glass) for comparison containing variable concentrations of Y

with a fixed concentration of Ce has shown a precision of about one percent in the Y/Ce ratio. Standards are also being made with variable

Ce and fixed Y.

A preliminary annealing study has been started at 1000 °C, using

Y-doped Ce02 at the 10/90 and 30/70 ratios prepared by thermally sintering

chemically prepared powders. The effects noted of the annealing on the

electrical properties will be used in designing the fuller study.
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RECYCLED OIL PROGRAM—Division 561 Activities

The Tribochemistry Group of the Chemical Stability and Corrosion

Division has the special assignment of providing a tecnical 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 oils.

Additionally, the Group provides, within the Center for Materials Science,

major competences in the chemical aspects of lubrication, friction,

wear, and characterization of complex hydrocarbons including lubricants.

Tribochemi stry

Subtask of Recycled Oil Program

S. M. Hsu, J. J. Comeford, A. L. Cummings, H. J. Brown P. T. Pei,

S. J. Weeks, R. S. Gates, D. E. Mathews, C. S. Ku

Current technical effort is directed mainly toward development of

measurement methods and standards for re- refined lubricating oils used

as automotive crankcase oils.

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 basestock between

periodic engine sequence test qualifications. These test procedures are crucial in order to accomodate re- refined oils within the existing

API-SAE-ASTM classification system. (Note: API = American Institute;

SAE = Society of Automotive Engineers; ASTM = American Society for

Testing and Materials). Development and evaluation of these tests by

NBS are particularly difficult because no such set of test procedures

exists for virgin lubricating oils. Historically, virgin oil producers

were instead required to control the crude source and refining technology.

This option is not applicable to oil recyclers.

There has been sufficient engine testing on re-refined oils to

establish that: (1) a high quality re-refined lubricating oil which has

been formulated with a high quality additive package can be comparable

to a virgin oil similarly formulated, and (2) that both will provide

adequate performance in most types of automotive service. The problem

which exists at the present time is the lack of technical information

and data to determine which tests are necessary and how often they

should be applied in order to assure that the re-refined oil basestock

is consistent between the engine tests.

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.

Accomplishments last year incluae the evaluation of six pnvsical

properties test procedures, four cnemical property test procedures, and

five test procedures in the performance area. We have also initiated
the ASTM/NBS basestock consistency program to examine the consistency of

basestocks produced commercially. Important experimental competences in

wear, hydrocarbon separation, and characterization have been estaolished

through equipment procurement and staffing.

There are six projects: physical properties, chemical properties,

hydrocarbon separation, oxidation stability and deposit simulation,

friction and wear, and NBS/ASTM Basestock consistency study. These

projects are described below.

Physical Properties : The main objective in this area has been to establish

a laboratory capable of producing data on all typical physical properties

necessary for the characterization of lubricating basestocks and other

petroleum products. The physical property methods, most of which are ASTM methods, were evaluated with particular emphasis on their applicability

to re-refined basestocks. Seven re-refined base oils were purchased

from various re-refiners throughout the country in ten drum lots. After

detailed characterization, these oils could serve as reference materials

for testing by various organizations and laboratories. Data on a selected

set of virgin basestocks were accumulated for comparison. The test

methods used are: kinematic viscosity at 40 °C and 100 °C, low temperature

viscosity at -IS °C, viscosity index, color, pour point, API gravity,

density at 20 °C, refractive index, and flash point. Establishment of

this data base on virgin and re-refined base stocks allows the use of

correlation programs to help characterize their quality. The simulated

boiling point distribution by gas chromatography method is currently

Deing evaluated.

The physical properties laooratory has been utilized by the Office

of Standard Reference Materials (QSRM) to measure sulfur in residual

fuel oil SRM's. The instrumentation has also been used in conjunction

with projects in the Center for Analytical Chemistry (CAC) and the

Center for Mechanical Engineering ana Process Technology (CMEPT) of NEL.

Chemical Properties : Evaluation of chemical test methods for characterization using a set of reference re-refined and virgin basestocxs is unaerway.

Seven test methods were studied. These induce ash, sulfur, water,

total acid number, nitrogen, basic nitrogen, and caroon resicue. Seme

of these are higniigntea oelow.

Ash: Ash content of an oil refers to the metal content of an oil

after comoustion. Some metals such as ’ead and magnesium can be lost

during the comoustion process cue to the low boiling points of their

oxices. Sulfuric acid can be accea to convert the oxice to sulfates.

This is then cal lea the sul'atea ash. Three ashing methods, AS7M D^S2

v'-egular"), CS7- (sulfated), ana wet ashing were investigated. The

uti'-ty of the met.nocs as a s': mo'e means for monitoring residual metal

content of case oi's has ceen establishea anc a modification of AS~M

-et.ncc 237- cevelccec, extending the lower ~ance of applicability of the

“et.noc. r or the -eferenca group of 17 casestocKS run in triplicate, the

Sweatee ash for the tan re- refined case stoexs -ancea “-cm 3.0QC5 to

7.013 cercent with a mean value of 0.0056 cercent. The seven virgin

casestcc<s in the grcub -ancea from 0.0000 to 0. 003S cercent with a mean
value of 0.0007 percent. The ash values for the re-refined stocks in

general were significantly higher than for the virgin stocks. This

corresponded to significantly higher metal contents for the re-refined

stocks as determined by atomic absorption and atomic emission spectrometry.

Degree of metal retention during ashing was determined for the

three methods by adding known amounts of metals to metal free oils,

ashing the sample, dissolving the ash and analysis by atomic absorption

spectrometry. Single element additions for Mg and Pb were done for each

method and five element additions for two levels of metal were completed.

Ca, Fe, and Zn recoveries were essentially 100 percent for all ashing

methods. Retention of Mg and Pb was 80 percent for wet ashing and 80

and 50 percent, respectively, for the sul fated ash. Lead recovery was quite poor for the regular ash (30 percent).

Water Content: Water content in a relatively pure oil is limited

by the solubility water in oil. In re-refined oils, there is a potential

contamination of residual dispersant/detergent molecules which could

increase the amount of water solubilized in oil drastically. Water

content in base oils is undesirable with respect to corrosion.

In order to establish a procedure by which water in base oils could

be accurately and efficiently determined, we considered several methods.

Variations of the Karl Fischer Titration Method were identified as the

best candidates for our purposes. We have begun critical experimental

evaluation of the sensitivity, accuracy and reproducibi 1 ity of some of

these methods. So far we have evaluated effects of solvents and oils on * the reproducibi! ity and analysis time of direct Karl Fischer Titrations.

In addition, we have compared three potential water standards, determined the moisture content of seven virgin and ten re- refined base oils

by direct titration and begun preliminary tests of an azeotropic distillation method.

Total Acid Number/Total Base Number: Of all of the complex con- stituents in a lubricating oil, acidic and basic properties are con- sidered to be important. The acid number indicates the amount of acidic

species in an oil which could be detrimental to performance by causing

corrosi on.

The ASTM methods for the determination of these acidic and basic

compounds are ASTM 0-664 and D-2896. 3oth are potentiometri c titration

methods. D-664 is proposed for both TAN (Total Acid Number) and T3N

(Total Base Number). 0-2896 is proposed for TBN only. We found 0-664

is applicable to re-refined base oils and 0-2896 needs modifications.

The data collected indicate that the TAN of re-refined base oils is

much higher than that of virgin base oils.

Sasic Nitrogen Content: Lubricating basestocks are complex hydrocarbon mixtures of paraffinic, naphthenic, and aromatic molecules.

There are very few "pure 11 molecules and most molecules exist as mixed

types. A small but important fraction of basestocks consist of molecules containing nitrogen, sulfur, and oxygen moieties.

63
The reaction of acetous HC10 4 with base oil samples has been investigated to estimate the amount of nitrogenous bases present in base oils.

We combined two published non-aqueous titration methods and have analyzed

lubrication base oils (no additives) from 17 sources in triplicate. The

results are usually expressed in two ways: (1) the Total Base Number

(TBN); (2) the number of micrograms of nitrogen per gram of oil, assuming

that the only bases in the oil are monobasic nitrogen compounds. The

data indicate that virgin base oils contain about an order of magnitude

more basic nitrogen than do re-refined base oils.

Hydrocarbon Separation/Characterization : Lubricating oil basestocks are complex mixtures of several types of hydrocarbons. Their detailed

molecular composition, while difficult to elucidate, is critical to

their performance. Structural characteristics, for example, may hold

the key to some observed but as yet unexplained phenomena, such as the

observation that sulfur compounds can increase or decrease base oil

additive response depending on the crude source.

This portion of the program is concerned with methodology for

separation of base hydrocarbon materials into aromatic, saturate, and

polar fractions. Gradient elution liquid chromatography is the method

of choice for this separation. The polar fraction separated by this

technique is of particular interest, since it comprises the most active

molecular species in a lubricating base oil. Detailed analytical information on the polar material can then be obtained with a variety of

techniques including high pressure liquid chromatography, gas chromatography, mass spectrometry, nuclear magnetic resonance, and IR and UV

spectroscopy.

The clay-gel chromatographic methods in the ASTM procedure (ASTM

D-2007) and its modification (Exxon-Baytown Clay-gel method) were both

investigated. The amount of sample charge is 10 gm. The saturated and

polar fractions were eluted from the columns by n-pentane and acetonetoluene (50/50) by volume, respectively. The aromatic fraction is

either determined by the material balance as in ASTM D-2007 or by re- fluxing the clay-gel column with toluene as in the Exxon-Baytown method.

The agreement of the two methods, especially for the aromatic fractions,

is excellent. The data indicate that the polar fraction content of

re-refined base oils is generally higher than the virgin base oils. The

significance of this difference will be examined with various oxidation

tests.

We recently acquired a High Performance Liquid Chromatography

(HPLC) system consisting of a Preparative unit and Analytical HPLC.

Work has started in developing better separation schemes using HPLC.

Techniques employing absorption spectroscopy , both ultraviolet and

infrared, are being investigated for the characterization of lubricating

oil base stocks. Included are methods for the. analysis of hydrocarbon

fractions obtained by various separation techniques. A data terminal

has been interfaced with the infrared spectrophotometer providing a capability for storage and retrieval of spectrograms as well as software

for automated spectral library searches and the generation of spectral

libraries for appropriate classes of compounds.

e.:
It is anticipated that this system with the development of hydrocarbon

and additive spectral libraries will be a vital element in compound

identification.

Oxidation Stability and Deposit Simulation : In the area of performance

tests for automobile crankcase oils, the industry-accepted tests include

the current engine sequence tests (IIC, II IC , VC, L-38), laboratory

truck engine tests (1H2, LGs, 10, EMD, T02), full-scale truck engine

tests (Mack T-5), fleet tests (Aunt Minnie type, taxi/police fleet heavy

duty type, commuter type, tire-track, and EPA cycle type). The expenses

involved in running these tests are enormous. There are no commonly

accepted chemical /physical laboratory bench tests for indicating in-service

performance.

The performance requirements of an automobile crankcase oil are rust protection, corrosion resistance, low temperature dispersancy (to

prevent sludge formation), detergency (to keep engine parts clean),

solvancy (to solubilize oxidized products), high temperature stability

(to keep piston rings from sticking), viscosity-temperature characteristics (to maintain hydrodynamic lubrication), anti -wear properties, and

low frictional resistance. In addition, the oxidation stability of the

oil is common to most of these requirements. Laboratory equipment and

test procedures for these various performance requirements are numerous

(over 100 variations of equipment and test procedures for measurement of

friction and wear are contained in a single ASLE publication).

The program plan of the performance testing areas will make use of

ASTM Reference Oils as a tool to screen promising procedures. The

reference oils are currently being used to monitor all the certified

engine test stands in the various testing laboratories all over the

United States and in some foreign countries. Some of these Reference

Oils even have fleet test data available. These oils can be classified

into good, bad, and borderline performance oils. By using these Reference

Oils, test procedures can be screened for correlation with in-service

performance.

The accomplishment in this area has been the completion of a specialized

oxidation laboratory facility. Work has started on the test development

of oil oxidation mechanism and simulation. Two procedures were used:

the Rotary Bomb Oxidation Test (RBOT) and Oil Thickening Test (QTT).

The Rotary Bomb Oxidation Test (ASTM D-2272) has long been used in

industry to screen antioxidants. A total of 10 re-refined oils and seven virgin base oils were tested at standard ASTM conditions of 150 °C

in the presence of the copper metal catalyst and water. No chemical

additives were used in the tests. The results suggest that the re-refined

base oils generally have better stability than the virgin base oils.

The repeatability of the test is ± 10 percent.

The standard test procedure provides an easy and quick method to

obtain information on the oxidation stability of base oils. However,

the use of water and copper catalyst in the test do not reflect the
engine in-service conditions. Preliminary studies on additive responses

of several oils were also conducted. Results indicate that at higher

antioxidant concentration (zinc dithiophosphate) the additive response

(oxidation stability improvement) of re-refined base oil appears to be

better than that of virgin base oils. Other additive systems will be

used to examine the additive response question further.

Preliminary OTT data on a 1QW-40 commercial oil were collected.

Experiments were run at 175 °C, a gas flow rate of 60 cnrVmin, and with

catalysts such as iron powder, copper powder, ferric naphthenate, and

N02

.

Results suggest that within a batch, repeatability is good, but the

batch-to-batch repeatability needs further study for improvement. In

general, the soluble catalyst (ferric naphthenate) causes more oil

thickening than the solid catalyst (iron powder and copper powder).

Friction and Wear : The emphasis in this area is on the chemical aspects

of friction and wear. For re-refined base oils derived from many sources

of used oils, potential contamination by cutting oil additives, and

metal -forming oils could have a significant effect on friction and wear

characteristics of the final product.

A laboratory module has been specially equipped to accommodate

three wear test apparatus: ring-on-block, four-ball, and pin-and-v. A new four-ball wear tester was specially designed to increase its load,

speed range, and ease of wear debris collection and analysis. We have

also acquired the Motor Industry Research Association (MIRA) Cam and

lifter wear tester which employs the actual cams and lifter parts of an engine. This is the first of its kind in the United States.

The objective in this area is to evaluate various laboratory wear

test procedures with respect to their ability to measure the wear performance of lubricating oils. Laboratory bench tests have long been a popular method of evaluating an oil's ability to lubricate because they

are more repeatable, far less expensive, easier to run and more sensitive

to chemical effects than full-scale engine or fleet tests.

The bench test procedures were evaluated using a set of five ASTM

HID Engine Sequence Test Reference Oils. These Reference Oils have a significant data base and have shown a correlation to actual field

performance. The wear data obtained from the engine sequence tests

shown in table 1 indicate that the oils can be roughly classified as high or low wear oils. Slow sliding tests performed on a Fa! ex Four-Ball

wear tester failed to show any significant difference in wear performance

between the reference oils. The anti -wear additives in an oil also

function as antioxidants; therefore, an attempt was made to observe the

effect of oxidation on wear performance. Reference oils, which are oxidized under identical conditions and run in identical wear tests,

showed different responses to wear as shown in table 1. The interesting

feature of this is that the high wear reference oils have a greater

increase in wear because of oxidation than the low wear reference oils.
I

I

I

I

I

An attempt is currently being made to increase the severity of the

oxidation to see if the trend of separation between the high and low

wear reference oils can be enhanced.

A series of load capacity seizure tests run on the Falex Four-Ball

wear tester have a good correlation to the engine sequence test results.

The high wear reference oils seize at below 180 kg while all three of

the low wear reference oils were able to take loads of above 180 kg

before seizure occurred.

A new research quality Roxana Four-Ball wear test machine was received in the spring of 1980, and initial testing on the effect of

base stock impurities on wear has begun.

Table 1

Test Results

Reference Oils

Test Description 76-A 75B-1 79A 77B-1 77C

Sequence HID Enqine Wear Test

tarn + Lifter Wear, cm x 10 4 48 46 48 287 277

| wear Classification Low Low Low High High

i-Ball Wear Test

1 Slow si idinq Test 1 Wear Scar diameter, cm x 10 3

w/o oxidation

31 33 33 31 29

Wear Scar diameter1

, cm x 10 3

w/oxidation2

36 35 37 40 37

Step-loadinq Siezure Test3

seizure load, kg 200 227 218 154 127

1 Test Conditions: 22.7 kg load, 75 °C, 60 minutes, 200 rpm.

3 Test Conditions: 75 °C, 200 rpm.
ASTM/NBS Basestock Consistency Study : In conjunction with ASTM, we are jointly sponsoring a study to collect information and data to determine

which tests are necessary and how often they should be applied in order

to assure that the re-refined basestock is consistent between the engine

tests.

The user industries are concerned about the potential lack of con- sistency of re-refined oil products, and about the potential effects of

unusual or unknown contaminants in the used oil feedstock to

re-refineries. These potential problems are of particular concern when

warranty questions are involved.

In this one-year study, four virgin oil producers and six re- refined

011 producers are submitting monthly samples for analysis by a group of

12 organizations, including NBS (Table 2a). These laboratories will

analyze the coded samples using over 40 different chemical, physical,

and performance tests. The program has been underway since March, 1980.

It is expected that the results from this study will provide much

of the data necessary to indicate an appropriate set of test procedures

to monitor re-refined basestock consistency.
Table 2

Organizations Cooperating in the ASTM/N8S Basestock

Consistency Study and the Tests

Organizations

Bartlesville Energy Technology Center

Chevron, USA

Gulf R&D

Lubrizol

Mobil Oil Corporation

National Bureau of Standards

National Research Council of Canada

Suntech, Inc.

Texaco

U.S. Army MERAOCOM

Tests

Physical Property Tests

Demulsibility

Fi 1 terabi 1 ity

Gravity

Color

Cold Cranking Simulator 0 to -40 °C

Mini-rotary Viscosity 10 to -40 °C

Brookfield Viscosity 0, -20, -40 °C

Viscosity at 40 and 100 °C

Viscosity Index

Refractive Index

Pour Point

Carbon Residue

Boiling Point Distribution

Foam

Chemical Property Tests

Total Acid Number

Saponification Number

Nitrogen, Sulfur

Hydrocarbon Type by

Mass Spect.*

Hydrocarbon Type by

Liquid Chromatography

Emission Spectrograph

Bench

Additive response to oxidation*

Additive response to wear*

Rusti ng

LUBT0T

Halogens

Differential Infrared

Sunlight Stability

Additive Compatibility

Glycol Content

Seq III C Simulator

For Anti-oxidant Response

Differential Scanning Calorimetry

RB0T (Basestock + Additive)

Turbine Oil Oxidation*

*0n selected samples
1<1I '4I iiI iI
Other Activities of the

Chemical Stability and Corrosion Division

Invited Talks

Ultra-Black Coating for Optical and Solar Devices

Optical Society of America, Rochester, New York

C. E. Johnson

September 9, 1979

Studies of Passive Film Breakdown by Detection and Analysis of

Electrochemical Noise

International Conference on Non Traditional Approaches to Study

So lid- Electrolyte Interfaces, Snowmass, Colorado

U. Bertocci

September 27, 1979

Possible Applications of Non Traditional Techniques (SolidElectrolyte Interface) to Technological Problems

International Conference on Non Traditional Aporoaches to Study

Sol id- Electrolyte Interfaces, Snowmass, Colorado

J. Kruger

September 27, 1979

Some Aspects of Chemical and Biodegradation of Materials

Thiokol Corporation, Ventron Division, Beverly, Massachusetts

T. D. Coyle

October 5, 1979

Current Progress in the Determination and Speciation of Trace

Organometals by HPLC

Washington Chromotography Discussion Group, Gaithersburg, Maryland

F. E. Brinckman

October 18, 1979

Some Issues Affecting Corrosion Protection

Naval Ship Research and Development Canter, Annapolis Coll oaui urn, Annapolis, Maryland

J. Kruger

October 19, 1979

The Four-Ball Wear Test for Engine Oil Evaluation

Joint Conference on Measurements and Standards for Recycled

Oil/Systems Performance and Durability, NBS, Gaitnersourg,

Maryland

R. S. Gates

October 24, 1979
Characterization of Lubricating Basestocks

Joint Conference on Measurements and Standards for Recycled

Oil /Systems Performance and Durability, NBS, Gaithersburg, Maryland

S. M. Hsu

October 24, 1979

Engine Oil Evaluation Through Bench Testing

Joint Conference on Measurements and Standards for Recycled

Oil /Systems Performance and Durability, NBS, Gaithersburg, Maryland

S. M. Hsu

October 25, 1979

Unique Surface Morphology with Extremely High Light Absorption

Capacity

Electroless Nickel Conference, Cincinnati, Ohio

C. E. Johnson

November 6, 1979

An Overview of the Microbial Corrosion of Underground Metallic

Structures

American Society for Testing and Materials Symposium on Underground Corrosion, Williamsburg, Virginia

W. P. Iverson

November 26, 1979

Alkali Vapor Transport Over Coal Minerals and Slags

Materials Research Society Annual Meeting Symposium on Coal:

Materials Properties and Conversion, Cambridge, Massachusetts

J. W. Hastie

November 1979

Measuring the Corrosion Rate of Steel in Concrete

Federally Coordinated Program (FCP) Conference on Highway Research

and Development, Williamsburg, Virginia

E. Escalante

December 5, 1979

Microbial Activity in Western Coal Mine Spoils

Biochemistry Group, Clinical Center, National Institutes of Health,

Bethesda, Maryland

G. J. Olson

December 7, 1979

Modern Approaches Toward Measurement of Corrosion in Practical

Envi ronments

Joint Chesapeake Section, American Society of Nondestructive

Testing and Baltimore American Society of Metals Meeting,

Baltimore, Maryland

J. Kruger

December 17, 1979

7 •:
Speciation of Qrganoarsenical s in Oil Shale Process Waters

Health and Environment Division, Department of Energy, Germantown,

Mary! and

F. E. Brinckman

December 20, 1979

New Approaches in Corrosion Research

Combined Boston sections of NACE (National Association of Corrosion

Engineers) and ECS (Electrochemical Society), Boston, Massachusetts

J. Kruger

January 16, 1 980

Economic Effects of Metallic Corrosion in the United States (NBS

Study)

Texas Instruments Labs, Attleboro, Massachusetts

J. Kruger

January 17, 1980

Current Trends and Prospects in Speciation of Environmentally

Important Trace Organometall ic Compounds

Lawrence Berkeley Laboratory, Berkeley, California

F. E. Brinckman

January 24, 1980

Studies of the Propagation of Transgranular Stress-Corrosion Cracks

in FCC Alloys

Metallurgy Department Seminar, University of Connecticut, Storrs,

Connecticut

E. N. Pugh

February 13, 1980

Chemistry and Flame Retardancy

Northern West Virginia Section, American Chemical Society

Morgantown, West Virginia

T. D. Coyle

March 3, 1980

Chemistry and Flame Retardancy

Kanawha Valley Section, American Chemical Society

South Charleston, West Virginia

T. D. Coyle

March 4, 1980

Chemistry and Corrosion

Central Ohio Valley Section, American Chemical Society

Huntington, West Virginia

T. D. Coyle

March 5, 1980

Chemistry and Corrosion

Western Maryland Section, American Chemical Society

Cumberland, Maryland

T. D. Coyle

March 6, 1980
Thermodynamic and Property Measurements of Liquid Tungsten

NASA—Marshall Space Flight Center

0. W. Bonnell

March 13, 1980

Employment of the Deaf in Science: Barriers and Progress

Gallaudet College Science Day, Gallaudet College, Washington, DC

E. J. Parks

March 18, 1980

Coupling Ferrography with Wear Testing as an Aid to Lubricant

Eva! uation

Ferrography Workshop, Technical Support Center—Joint Oil Analysis

Program, Pensacola, Florida

R. S. Gates

March 19, 1980

Microbial Transformations of Heavy Metals

Los Alamos Scientific Laboratory, University of California,

Los Alamos, New Mexico

W. P. Iverson

March 25, 1980

A Review of the National Bureau of Standards Recycled Oil Program

Waste Oil Management Conference, ASLE—Chicago Section and

Illinois Institute of Natural Resources, Amoco Research Center,

Chicago, Illinois

S. M. Hsu

April 3, 1980

A Review of the ASTM Basestock Consistency Study Plan

Waste Oil Management Conference, ASLE—Chicago Section and Illinois

Institute of Natural Resources, Amoco Research Center, Chicago,

Illinois

S. M. Hsu

April 3, 1980

Microbial Transformations of Heavy Metals

Microbiology Class, Dr. Norman Gary— Instructor, Hood College,

Frederick, Maryland

W. P. Iverson

April 17, 1980

Study of Transport Properties in Polycrystall ine Ceramics Using

Impedance Measurements

College of Earth and Mineral Sciences, Pennsylvania State University,

University Park, Pennsylvania

A. D. Franklin

April 24, 1980
A Review of Laboratory Bench Tests in Assessing the Performance of

Automotive Crankcase Oils

ASLE Annual Meeting, Anaheim, California

S. M. Hsu

May 5, 1980

Re-refined Lubricating Base Oils: Establishing Consistency

and Quality

ASLE Annual Meeting, Anaheim, California

S. M. Hsu

May 6, 198Q

Soils and Underground Corrosion

Gas Transmission Conference, American Gas Association,

Salt Lake City, Utah

E. Escalante

May 6, 1980

Simulation of Engine Tests Using Laboratory Bench Tests

Chevron Research Company, Richmond, California

S. M. Hsu

May 9, 1980

Re- refined Lubricating Base Oils: Establishing Consistency

and Qua! ity

API Refining Meeting, Houston, Texas

S. M. Hsu

May 13, 1980

Recent Observations on the Propagation of Stress-Corrosion Cracks

and Their Relevance to Current Models for Stress-Corrosion Cracking

A. R. Troiano Honorary Symposium on Hydrogen Embrittlement and

Stress Corrosion Cracking, Case Western Reserve University,

Cleveland, Ohio

E. N. Pugh

June 3, 1980

New Developments in the Economics and Science of Corrosion

Burgess Memorial Lecture, Washington Chapter- American Society

for Metals, Bethesda, Maryland

J. Kruger

June 4, 1980

Effects of Base Stock Chemical Composition of Friction and Wear

Gordon Research Conference Friction, Lubrication and Wear,

Colby—Sawyer College, New London, New Hampshire

S. M. Hsu

June 9, 1980

Bacterial Corrosion

Gas Operations School

New England Gas Association, 3entley College, Waltham, Massachusetts

W. P. Iverson

June 12, 1980
Biomethylation of Tin

Organotin Environmental Program Association (ORTEPA)

L‘ Enfant Plaza Hotel, Washington, DC

F. E. Brinckman

June 19, 1980

NBS Program in Chemical Stability and Corrosion Division

Organotin Environmental Program Association (at NBS Gaithersburg)

T. D. Coyle

June 19, 1980

Morphology of Immersion Deposits on Aluminum

American Electroplaters 1 Society, Atlanta, Georgia

0. S. Lashmore

June 25, 1980

Studies of the Propagation of Stress-Corrosion Cracks

Corrosion Section Seminar, Battel le Columbus Laboratories

Columbus, Ohio

E. N. Pugh

July 14, 1980

Transport Properties by Impedance Measurements for Solid

Electrolyte Fuel Cells

National Fuel Cell Seminar, San Diego, California

A. D. Franklin

July 15, 1980

Corrosion

Sagamore Army Materials Research Conference on Surface Treatments

for Improved Performance and Properties, Lake George, New York

J. Kruger

July 17, 1980

Molecular Chemistry at High Temperature

IBM, Yorktown Heights, New York

J. W. Hastie

July 22, 1980

Evidence for the Discontinuous Nature of Transgranular StressCorrosion Cracking in FCC Alloys

Gordon Research Conference on Corrosion, Colby—Sawyer College,

New London, New Hampshire

E. N. Pugh

July 22, 1980

A Qualitative Ellipsometric Approach to Studying Film Growth

Under Organic Coatings

Gordon Conference on Corrosion, Colby—Sawyer College, New London,

New Hampshire

J. J. Ritter

July 24, 1980

73
Environmental Qrganotin Chemistry: Experiences in the Field and

Laboratory (Plenary Lecture)

3rd International Conference on the Organometall ic and Coordination

Chemistry of Germanium, Tin, and Lead; University of Dortmund;

Dortmund, West Germany

F. E. Brinckman

July 24, 1980

High Temperature Chemistry of Flames and Slags

Aerodyne Research, Inc. , Bedford, Massachusetts

J. W. Hastie

July 25, 1980

Applications of Transpi ration Mass Spectrometry

Gordon Research Conference: High Temperature Chemistry

Plymouth, New Hampshire

D. W. Bonnell

August 4, 1980

High Temperature Chemistry of Flames and Slags

General Electric Central Research Laboratory, Schenectady, New York

J. W. Hastie

August 1

1 , 1980

Studies of Hydrogen Embrittlement and Stress-Corrosion Cracking

in an Al-Zn-Mg Alloy

. 3rd International Conference on Effect of Hydrogen on Behavior of

Materials, Jackson Lake Lodge, Wyoming

E. N. Pugh

August 28, 1980

Activities of the NBS Chemical Stability and Corrosion Division

International Tin Research Institute, Greenford, England

T. D. Coyle

September 1, 1980
Technical and Professional Committee Memberships

American Chemical Society

Inorganic Chemistry Division—Nonmencl ature Committee

T. D. Coyle, Chairman

American Association of Civil Engineers

Committee on Corrosion Protection of Steel Structures

W. F. Gerhold, Member

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 Testing and Materials

AQ5: Metallic Coated Iron and

W. F. Gerhold, Chairman,

teel Products

Member:

A05.09: Advisory, Chairman

A05. 14: Sheet Tests

A05.15: Wire Tests

A05.16: Hardware Tests, Chairman

B08: Electrodeposited Metallic Coatings and Related Finishes

F. Ogburn, Member:

B08.01: Terminology, Editing Public Relations

and Metrication

WG.05: Metrication, Chairman

303.03: Decorative Copper, Nickel, Chromium,

and Nickel -Chromium Coatings

WG: Electrodeposited and Electroless

31ack Coatings for Solar Use

B08.04: Zinc and Cadmium Coatings

B08.05: Coatings of Tin, Lead, and Their Alloys

808. 06: Anodic and Chemical Conversion

Coatings on Aluminum and Magnesium

A1 loys

308.08: Engineering Coatings

308.09: Precious Metal Coatings

808.10: General Test Methods

WG.01: Measurement of Coating

Thickness, Chairman

308.11: Government Specifications, Chairman

B08.20: Technical Advisory Groups to

ISO/TC 107

0. S. Lashmore, Member:

B08.02: Substrate Preoaration

308.03: Decorative CopDer, Nickel, Chromium,

ana Nickel -Chromium Coatings

WG: Electrodeposited and Electroless

Black Coatings for Solar Use

303.08: Engineering Coatings

308.10: General Test Methods
C5: Manufactured Carbon and Graphite Products

W. S. Horton, Member:

C5.02: Nomenclature, Units, and Editorial

Matters, Chairman

C5.05: Nuclear Applications

C5.06: Executive Subcommittee

D2: Petroleum Products and Lubricants

S. M. Hsu, Member:

T-B:

T-B-II:

T-Jt.B/P:

T-P:

T-P-II:

T-P-III:

ROD- II:

RDD-IV:

RDD-IX:

C. Ku, Member

R. Gates, Member:

T-L:

J. J. Comeford, Member:

C-I:

T-E-I:

RDD-IV:

RDD-IV-F:

T-P:

T-P- I: T-P-II:

T-P-III:

T-P- IV:

T-P-VI:

T-P-VI I: RDD-IX-F:

A. L. Cummings, Member:

RDD-III-A:

RDD-III-C:

RDD-VI-A:

RDD-Jt. API/ASTM:

P. T. S. Pei, Member:

RDD-III:

RDD-III-A:

RDD-IV:

RDD-IV-A:

RDD-IV-C:

RDD-VI:

Automotive Lubricants

Heavy Duty Engine Oils

Basestock Characterization

Recycled Petroleum

Used Oils and Basestocks

Fuel Oils

Elemental Analysis

Flow Properties

Oxidation

Industrial Lubricants

Advisory Committee

Burner Fuel Oils

Hydrocarbon Analysis

Absorption Spectroscopy

Methods

Recycled Petroleum Products

and Lubricants, Advisory,

Vice-Chai rman Automotive Lubricants

Used Oils and Base Stocks

Fuel Oils, Chairman

Industrial and Hydraulic

Oils

Miscellaneous Products

Editorial

Used Oils Oxidation-Nitration

Chemical Methods

Electrometric Method

Chemical Analysis

Water and Sediment

Elemental Analysis

Chemical Methods

Hydrocarbon Analysis

Chemical Analysis

Liquid Phase Chromatography

Analysis of Lubricants
El 3

E34:

GO!

S. J. Weeks, Member:

T-P:

ROD- III:

RDO-IV:

RDD-VII:

Recycled Petroleum Products

Elemental Analysis

Hydrocarbon Analysis

Flow Properties

Molecular Spectroscopy

R. B. Johannesen, Member:

El 3. 07: Nuclear Magnetic Resonance,

Chairman

Occupational Health and Safety Aspects of Materials,

Physical and Biological Agents

F. E. Brinckman, Member:

E34.10: Definitions and Nomenclature,

Co-Chairman

Corrosion of Metals

U. Bertocci , Member:

G01.ll: Electrochemical Measurements in

Corrosion Testing

E. Escalante, Member:

G01 .10: Corrosion in Soils, Chairman

W. F. Gerhold, Member:

G01. 01: Research

G01.Q4: Atmoshperic Corrosion

G01.05: Laboratory Corrosion Tests

G01.06: Stress Corrosion Cracking and

Corrosion Fatigue

G01.98: Advisory Committee on Exposure

Test Facilities

W. P. Iverson, Member:

GO! .10: Corrosion in Soils

TG: Electrochemical Polarization

Techniques for Measurement of

Corrosion Rates in Soils,

Chai rman

J. Kruger, Member:

G01.02: Nomenclature

GO 1.90: Executive Committee

G01.99: Standing Committee on Liaison, Chairman

E. N. Pugh, Member:

G01.06: Stress Corrosion Cracking and

Corrosion Fatigue

G01. 06. 05: Section on Dynamic Testing, Chairman

e:
Controlled Release Society (International)

Publications Committee

F. E. Brinckman, Member

Carnegie Mellon Institute of Research

Industrial Energy Productivity Project: Materials Trends Group

J. Kruger, Member

Electric Power Research Institute

Corrosion Advisory Committee

J. Kruger, Member

Electrochemical Society

Corrosion Division

J. Kruger, Member, Past Chairman

Editorial Committee

J. Kruger, Member

U. Berto'cci , Member

Technical Affairs Committee

J. Kruger, Member

Corrosion Monograph Series Committee

J. Kruger, Member

Federation of Materials Societies*

J. Kruger, Member,

Board of Trustees

Long-Range Planning Committee

Gordon Research Conferences

Counci 1 J. Kruger, Member

International Committee for the Characterization and Terminology of Carbon

W. S. Horton, Vice Chairman

International Corrosion Council

J. Kruger, Member & U. S. Delegate

International Standards Organization

TCI 07: Metallic and Other Non-organic Coatings

F. Ogburn, Delegate:

1: Terminology, Delegate

2: Methods of Inspection and Coordination of

Test Methods, Delegate

3: Electrodeposited Coatings and Related

Finishes, Delegate

7: Corrosion Tests, Oelegate

TCI 56: Corrosion of Metals

J. Kruger, Delegate:

1: Terminology, Oelegate
International Union of Pure and Applied Chemistry

II: Inorganic Chemistry Division

Division Committee

W. S. Horton, Member

Commission I 1-2: Nomenclature of Inorganic Chemistry

T. D. Coyle, Titular Member, Secretary

Commission I 1-3 : High Temperatures and Refractory Materials

W. S. Horton, Associate Member

Subcommission II-3.1: Characterization and

Terminology of Carbon,

Co-Chairman

Joint Committee of Atomic and Molecular Physical Data

R. B. Johannesen, Member: NMR Subcommittee

(Jointly Sponsored by the American Chemical Society, American

Physical Society, American Society for Mass Spectrometry

American Society for Testing and Materials, Coblentz Society,

Manufacturing Chemists Association, Optical Society of America,

Society for Applied Spectroscopy, and Spectroscopy of Society of

Canada.

)

National Association of Corrosion Engineers

International Relations Committee

J. Kruger, Liason Member

Government Affairs Committee

J. Kruger, Liason Member

Publications Committee

J. Kruger, Member

Technical Practices Committee

J. Kruger, Member

Standing Committee on Technology Assessment

J. Kruger, Member

T10: Underground Corrosion Control

E. Escalante, Member

T3: Corrosion Science and Technology

W. P. Iverson, Member

T3L: Electrochemical and Electrical

Techniques for Corrosion Measurement

and Control

J. Kruger, Member

SC.B: Corrosion Products

3 -
National Research Council

Committee on High Temperature Science and Technology

J. W. Hastie, Member

National Materials Advisory Board

Committee on Environmentally Assisted Cracking Test: Methods

for High Strength Steel Weldments

J. Kruger, Member

E. N. Pugh, Liason Representative

Committee on the Assessment of the Characterization (in-situ

Downhole) of Geothermal Brines, National Materials Advisory Board

U. Bertocci , Member

Committee on Radioactive Waste Management

Subcommittee on Review of Swedish KBS-2 Plan

J. Kruger, Member

(J. Bertocci, Consultant

Committee on Recommendations for II. S. Army Basic Scientific

Research

J. Kruger, Member:

Corrosion, Surfaces, and Interfaces Section,

Chairman

National Science Foundation

Faculty Research Participation Program

F. E. Brinckman, Panel Chairman

Offshore Technology Conference

Executive Committee

J. Kruger, Member

Surgeon's General Review Panel on Special Surveillance Program

for Leaking Weteye Bombs

J. Kruger, Member

U.S. /U. S.S. R. Study Group on Corrosion

J. Kruger, Member

Passivity and Electrochemistry Project Coordinator
Pud! i cations

Ultra-Black Coating for Optical and Solar Devices —A Summary

C. E. Johnson

J. Optical Society of America, 69, 1400 (October 1979)

Unique Surface Morphology with Extremely High Light Absorption

Capaci ty

C. E. Johnson

Proceedings of Electroless Nickel Conference, Cincinnati, Ohio,

Individual Volume (November 1979)

Fundamentals of Corrosion of Metallic Implants

J. Kruger

Corrosion and Degradation of Implants

3. C. Syrett and A. Acharya, Editors, ASTM STP 684, p. 107 (1979)

Stress Corrosion Testing at Elevated Temperatures in Simulated

Coal Conversion Gases

G. M. Ugiansky and C. E. Johnson

Proceedings of the 7th International Congress on Metallic Corrosion,

ABRACO, Rio de Janeiro, Brazil, p. 915 (1979)

The Role of Noncrystall i ne Films in Passivation and Breakdown of

Passivation

A. G. Revesz and J. Kruger

ibid., p. 330 (1979)

An Electrochemical Study of an Al-Zn-Mg Alloy

G. M. Ugiansky, J. Kruger, and R. W. Staehle

ibid., p. 605 (1979)

Detection and Analysis of Electrochemical Noise for Corrosion

Study

U. Bertocci

ibid. , p. 2010 (1979)

Application of a Graphite Furnace Atomic Absorption Detector

Automatically Coupled to a High Performance Liquid Chromatograph

for Speciation of Metal-containing Macromolecules

E. J. Parks, F. E. Brinckman, and W. R. Blair

J. Chromatography, 185 563 (1979)

International Cooperation on Characterization and Terminology of

Carbon and Graphite

W. S. Horton

Pure and Appl. Chem. , 51_, 1561, Pergamon Press, Ltd. (1979)

Spectroscopy and Photophysics of the CF 2 A^ 4 9 1 -X^ 4 A 1 System

D. S. King, P. K. Schenck, and J. C. Staphensen

J. Mol. Spec., 73, 1 (1979)

36
Improved Sensitivity for Laser Enhanced Ionization Spectrometry

in Flames by Stepwise Excitation

G. C. Turk, W. G. Mallard, P. K. Schenck, and K. C. Smyth

Analy. Chem. , 5J_, 2408 (December 1979)

Slow Transient Phenomenon in Y-Doped Ce0 2 C. K. Chiang, A. L. Dragoo, and A. D. Franklin

Proc. of International Conference on Fast Ion Transport in Solids,

Electrodes, and Electrolytes, p. 661, Lake Geneva, Wisconsin

(May 21-25, 1979)

Preparation of Pt-Fe Alloy Foils by Electrodeposition of Fe

A. D. Franklin and J. Epp

J. Electrochm. Soc. , 1_26, 2126 (1979)

State of the Art of Electrodeposition on Anodized Aluminum

D. S. Lashmore

Metal Finishing, 78, 21 (1980)

Progress in Plating on Aluminum

D. S. Lashmore

Plating and Surface Finishing, 67, 36 (1980)

A New Ellipsometric-Electrochemical Approach to the Study of

Corrosion Under Organic Coatings

J. J. Ritter and J. Kruger

Proceedings of Division of Organic Coatings and Plastics Chemistry,

American Chemical Society, San Francisco (1980)

Electroforming a Micrometer Scale of 50 pm (2 mil) Overall

Length

J. P. Young, F. Ogburn, and D. B. Ballard

Metal Finishing, 78, 8 (1980)

The Morphology of Immersion Coatings on Aluminum

D. S. Lashmore

Plating and Surface Finishing, 67, 37 (1980)

Thin Zinc Film on Aluminum

D. S. Lashmore

J. Electrochemical Society, 127 , 3 (1980)

Mossbauer Spectroscopy of Polycrystall i ne Steel Fibers

D. S. Lashmore, L. J. Swartzendruber , and L. H. Bennett

Applied Physics Letters, 36, 1 (1980)

A Low-Noise Potentiostat for the Study of Small Amplitude Signals

in Electrochemistry

R. W. Shideler and U. Bertocci

J. Res. NBS , 85, 211 (1980)
Thickness of Gold Coatings Measured with a Calibrated SEM

F. Ogburn and D. B. Ballard

Plating and Surface Finishing, 67, 49 (1980)

Black Electroless Nickel Surface Morpnologies with Extremely High

Lignt Absorption Capacity

C. E. Johnson

Metal Finishing, 78, 21 (July 1980)

Graphite Furnace Atomic Absorption Spectrophotometers as Automated

Element-specific Detector for High Pressure Liquid Chromatograph

(HPLC), the Determination of Arseni te, Arsenate, Methyl arsonic

Acid, and Dimethylarsinic Acid

F. E. Brinckman, K. L. Jewett, W. P. Iverson, K. J. Irgolic,

K. C. Ehrhardt, and R. A. Stockton

J. Chromatography, 1 91 , 31-46 (1980)

What Really Does Happen to Electronically Excited Atoms in Flames

K. C. Smyth, P. K. Schenck, and W. Gary Mallard

Amer. Chem. Soc. Symp. Series, 134 (1980)

Internal Friction and Sodium Transport in Beta Alumina

J. H. Simmons, A. D. Franklin, K. F. Young, and M. Linzer

J. Am. Ceram. Soc. , 63, 78 (1980)

Underground Corrosion

E. Escalante

Corrosion and the Building Industry, Building Science Series (NBS

BSS)

in press

A Field Study on the Corrosion of Concentric Neutral Cable

E. Escalante, U. Bertocci , and J. L. Mullen

Materials Performance

in press

The Location Effect on the Corrosion of Steel in Stagnant Solutions

S. Wolynec and E. Escalante

Corrosion Science

in press

Determination of True Polarization Curves for Corrosion Rate

Measurements of Steel in Stagnant NaCl Solutions

S. Wolynec and E. Escalante

Corrosion

in press

Cor-osicn Ennancement Due to Large Voltage Modulations. Frequency

Analysis of the Response of Electrodes Under Charge-Transfer

U. Bertocci and J. L. Mullen

3 -oceedi ngs of the ASTM Symposium on "Progress in Electrochemical

Corrosion Testing11 in oress
Underground Corrosion

E. Escalante

Corrosion and The Building Industry, National Association of

Corrosion Engineers Publication

in press

A Qualitative Ell ipsometric-Electrochemical Approach for the Study

of Film Growth Under Organic Coatings

J. J. Ritter and J. Kruger

Surface Science

in press

Possibilities for Application of Fundamental Approaches to Technological Problems

J. Kruger

Surface Science

in press

The Morphology of Polycrystalline Steel Fibers Produced by Thermal

Decomposition of Iron Pentacarbonyl in the Presence of a Magnetic

Field

D. S. Lashmore, W. A. Jesser, and H. G. F. Wilsdorf

J. Appl . Phys.

in press

Adhesion of Electrodeposited Coatings

D. S. Lashmore

J. of Adhesion

in press

Studies of Passive Film Breakdown by Detection and Analysis of

Electrochemical Noise

U. Bertocci and J. Kruger

Surface Science

in press

Applications of a Low-Noise Pctentiostat in Electrochemical

Measurements

U. Bertocci

J. Electrochemical Society

in press

Speciation of Trace De-and Triorganoti ns in Water by Ion Exchange

HPLC-GFAA

K. L. Jewett and F. E. Brinckman

J. Chrom. Soc.

in press

Characterization of Bioactive Qrganotin Polymers Fractionation

and Determination of MW by SEC-GFAA

E. J. Parks and F. E. Brinckman

Proceedings of the 7th International Symposium on Controlled Release

of 3ioactive Materials

in press

s:
An Overview of the Anaerobic Corrosion of Underground Metallic

Structures Evidence for a New Mechanism

W. P. Iverson

in press

Slag and Metal Oxide Vaporization in Reactive Atmospheres

J. W. Hastie, 0. W. Bonnell, and E. R. Plante

High Temperature Science

in press

Radiations and Conduction Loss Corrections to Free Drop Calorimetry

Data

D. W. Bonnell, A. J. Valerga, and J. L. Margrave

High Temperature Science

in press

Effect of Flame Boundary Layer in Line of Sight Optical Measurements

L. H. Grabner and J. W. Hastie

Combustion and Flame

in press

The Four-Ball Wear Test for Engine Oil Evaluation

R. S. Gates and S. M. Hsu

Proceedings-Joint Conference on Measurements and Standards for

Recycled Oil/Systems Performance and Durability, NBS, S.P. #584

in press

Review of Laboratory Bench Tests in Assessing the Performance of

Automotive Crankcase Oils

S. M. Hsu

Lubricating Engineering Journal

in press

Engine Oil Evaluation Through Bench Testing

S. M. Hsu

Proceedings of the Joint Conference on Measurements and Standards

for the Recycled Oil /Systems Performance and Durability, NBS,

S. P. #584

in press

Characterization of Lubricating Basestocks

S. M. Hsu

Proceedings of the Joint Conference on Measurements and Standards

for the Recycled Oil /Systems Performance and Durability, NBS,

S. P. #584

in press

Characterization of Re-refined Lubricating Base Oils

S. M. Hsu and D. A. Becker

A Society of Automotive Engineer

in press
Temperature Profiles of Inhibited Flames Using Raman Spectroscopy

M. C. Drake and J. W. Hastie

Combustion and Flame (in press)

Division Seminars

The Division Seminar Program has endeavored to arrange two talks

each month; one by a speaker within the Bureau and a second by a speaker

from outside- Responsibility for providing speakers rotates amoung the

Group Leaders. It has not been possible to follow the idealized schedule

exactly; however, we have had 31 talks scheduled in FY80, of whom all

but three were speakers from outside. A chronological list of talks follows:

Ion Transfer Reactions at Metal Electrodes and the Structure of

the Surface

K. E. Heusler

i{| Technische Universitat Clausthal-Zel lerfetd, West Germany

September 18, 1979

NMR Studies of Alkylated Coal

L. Alemany

University of Chicago, Chicago, Illinois

October 23, 1979

Chemical Models for the Environmental Transmethylation of Metals

J. S. Thayer

University of Cincinnati, Cincinnati, Ohio

October 25, 1979

Recent Advances in the Chemistry of Simple and Bi-Metallic Alkoxides

R. C. Mehrotra

University of Delhi, Delhi, India

November 7, 1979

Ester Oxidation at High Temperatures

F. Lockwood

General Motors Company, Michigan

November 16, 1979

Effect of Alternating Current on Corrosion of Low Alloy and Carbon

Steel

D. A. Jones

University of Nevada-Reno, Reno, Nevada

November 30, 1979

Toward the Preparation of an "Atlas of Chemical and Electrochemical

Equilibria in the Presence of a Gaseous Phase"

M. Pourbaix

CEBELCOR, Brussels, Belgium

December 6, 1979

a*

A
Ionic Transport Studies of Fluorites

A. Chadwick

University of Kent, Canterbury, England

January 8, 1980

Corrosion Protection by Ion-Implantation and Laser-Surface Alloying

E. McCafferty

Naval Research Laboratory

January 24, 1980

The Melting Behavior of Small Particles of Tin, Indium, and 8ismuth

W. A. Jesser

University of Virginia, Charlottesville, Virginia

January 25, 1980

Chemical Additives and Their Role in Automotive Lubrication

J. Udelhofen

Amoco Chemicals Research Center, Naperville, Illinois

January 30, 1980

Infrared Emission Spectra From an Operating Bearing—Generation,

Dependence on Operating Conditions, and Interpretation

J. A. Lauer

Rensselaer Polytechnic Institute, Troy, New York

February 1, 1980

Erosion-Corrosion Processes

J. Zahavi

Institute of Metals, Technion, Haifa, Israel

February 25, 1980

Dynamic Control of Particle Size Distribution and Agglomeration in

the Continuous Precipitation of Zi rconium-Yttri urn Hydroxides

L. E. Burkhart

Iowa State University, Ames, Iowa

March 4, 1980

Strain-Rate Effects in Environment-Sensitive Fracture

R. N. Parkins

The University of Newcastl e-Upon Tyne, England

March 13, 1980

Penn State Micro-Oxidation Project Review

E. E. Klauss

Pennsylvania State University, State College, Pennsylvania

March 17, 1980

The Electrochemi stry of Wrecks

I. 0. MacLeod

Western Australian Museum, Australia

April 3, 1980
The Coordination and Solution Chemistry of Benzothiazole-2-Thiol , -Selenol

Di alkyl and Diaryl-dithiophosphates , and Dithiophosphi nates

J. A. McCleverty

Department of Chemistry, Univeristy of Sheffield, Sheffield, England

April 7, 1980

Some Aspects of the Formation of Hydrides in Metals

B. Muddle

University of Illinois, Urbana, Illinois

April 16, 1980

The Mechanism of Stress-Corrosion Cracking and Corrosion Fatigue of

Austenitic Stainless Steels in Dilute Environments

F. P. Ford

General Electric Company, New York

April 23, 1980

Use of Impedance Spectroscopy in Studying Solid- Electrolytes

A. D. Franklin

Division 561, NBS

May 6, 1980

Electrochemical Noise

U. Bertocci

Division 561, NBS

May 16, 1980

Surface Analysis of Electrodes

J. Brace

University of Paris, France

May 19, 1980

The El ectrochemi stry of the Oxygen Electrodes

S. Srinivasan

Brookhaven National Laboratory, Long Island, New York

May 20, 1980

Applications of Pyrolytic Methyl ati on/Gas Chromatography in Organic

Analyses

W. C. Kossa, Jr.

Pennsylvania State University, State College, Pennsylvania

June 2, 1980

Use of Neutron Scattering to Study Hydrogen Effects in Metals

K. Hardman

NBS

June 23, 1980

High Temperature Chemistry of Phosphorous-Containing Flames

J. W. Hastie

Division 561, NBS

July 16, 1980

9 -
Diagrams of Chemical and Electrochemical Equilibria for the Systems,

0, H, Fe, 0-H-Fe

M. Pourbaix

CEBELCOR, Brussels, Belgium

July 17, 1980

The Application of Metal Vapor Lasers to Raman Spectroscopy for

Gas and Flame Diagnostics

1. Glatt

The Atomic Energy Commission, Israel

July 21, 1980

Recent Progress in High Temperature Microwave Spectroscopy

T. Torring

Freie Universitat, Berlin, Germany

July 31, 1980

Recent Developments in the Applications of ESCA to Corrosion Science

J. E. Castle

University of Surrey, Guildford, England

August 4, 1980

Localized Corrosion Behavior of Glassy Chromium Containing Alloys

R. B. Diegle

Battel! e Memorial Laboratory, Columbus, Ohio

August 22, 1980

Metal Cluster Chemistry: Simulation of Corrosion Inhibition

Y. Jeannin

Uni vers ite Pierre et Marie Curie, Paris, France

August 25, 1980

Chemistry and Sterochemi stry of FI uorophosphoranes: Recent Advances

R. Schmutzler

Technische Universitat Braunschweig, West Germany

September 19, 1980

9 -
External Recognition

Case Centennial Scholar

Case Western Reserve University

June 2-3, 1980

E. N. Pugh

Captain Alfred E. Hunt Award

American Society for Lubrication Engineers

San Francisco, California

August 1980

S. M. Hsu

Case Centennial Scholar

Case Western Reserve University

October 20-22, 1980

J. Kruger

1980 Gordon Research Conference on Corrosion

Invited Speakers —J. J. Ritter and E. N. Pugh

Discussion Leader—J. Kruger

1980 Gordon Research Conference on Physical Metallurgy

Discussion Leader—A. D. Franklin

1980 Gordon Research Conference on High Temperature Chemistry

Discussion Leader• —E. R. Plante

1980 Gordon Research Conference on Lubrication, Friction, and Wear

Invited Speaker—S. M. Hsu

IR 100 Award

Industrial Research and Development Magazine

Transpiration Mass Spectrometer

1980

D. W. Bonne!! and J. W. Hastie

Books

Characterization of High Temperature Vapors and Gases

Edited by J. W. Hastie

Proceedings of the 10th Materials Research Symposium, NBS,

September 18-22, 1979

NBS SP 561 , 2 Vols. , 1726 pages

1980

Early Pyrotechnol ogy

Edited by T. Wertime, A. Franklin, and J. 01 in

Proceedings of a Seminar, April 19-20, 1979

in press
Special Reports

Passive Films, Surface Structure, and Stress Corrosion and Crevice

Corrosion Susceptibility

J. Kruger, J. J. Carroll, A. J. Melmed, J. J. Ritter, and

J. R. Ambrose

NBSIR 79-1904 (Report to the Office of Naval Research), Technical

Summary Report No. 9 (November 1979)

Materials for Fuel Cells

L. H. Bennett, C. K. Chiang, M. I. Cohen, A. L. Oragoo, A. 0. Franklin,

and A. J. McAlister

NBSIR 80-1991 (Report to Division of Fossil Fuel Utilization, DOE)

(Annual Report January 1978-December 1978—issued March 1980)

Development of _In Si tu Techniques for the Detection and Measurement

of Corrosion of Copper Concentric Neutrals in Underground

Envi ronments

J. Kruger, U. Bertocci , E. Escalante, and J. L. Mullen

NBSIR 80-2083 (Report Prepared for DOE, January 1980)

Final Issued June 1980

Measuring The Rate of Corrosion of Reinforcing Steel in Concrete

E. Escalante, S. Ito, and M. Cohen

NBSIR 80-2012 (Annual Report prepared for the Federal Highway

Administration) (March 1980)

• Anodizing and Immersion Processes

D. S. Lashmore

NBSIR (Report to Aluminum Association)

in press

Passive Films, Surface Structure and Stress Corrosion and Crevice

Corrosion Susceptibility

J. Kruger, J. J. Carroll, A. J. Melmed, and J. J. Ritter

NBSIR (Report to the Office of Naval Research) Technical Summary

Report No. 10

in press

A Review of Techniques for Measuring the Corrosion of Metals in

Concrete

E. Escalante

NBSIR (Report to the Federal Highway Administration)

in press

Use of the Slow Strain Rate Technique for the Evaluation of

Structural Materials for Application in High Temperature Gaseous

Envi ronments

G. M. Ugiansky and C. E. Johnson

NBSIR

in press

56
Molecular Chemistry of Inhibited Combustion Systems

J. W. Hastie and D. W. Bonnell

NBSIR (Final Report to Army)

in press

Materials for Fuel Cells

C. K. Chiang, M. I. Cohen, A. L. Oragoo, and A. D. Franklin

NBSIR (Report to the Division of Fossil Fuel Utilization, Department

of Energy)

in press

Standard Reference Materials

The Division produces coating thickness SRMs, used to calibrate

coating thickness gages. A single SRM is a metal coupon, 3 x 3 cm or 1.5 x 1.5 cm, one surface of which has an electroplated 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 made

ranging in thickness from 0.7 pm to 2 mm. (Gold coatings are actually certified in units of mass/area, not length.) They are designed for use with either magnetic type or beta backscatter

type thickness gages.

These SRMs are packaged in sets and the SRM catalog lists some 31 different sets. About 3000 individual coating thickness

standards were produced during FY79, and about 5000 were produced

during FY80.

The Division is also in the process of developing NMR SRMs

to be used for calibration of NMR spectrometers. A single SRM

will consist of two seven- inch long NMR tubes, 5 mm and 10 mm

(or 12 mm) in diameter, respectively. The tubes will contain a mixture of organic liquids sealed in an inert atmosphere and will

be calibrated for proton line positions (five lines) and carbon- 13

line positions (eight lines). It is expected that the initial

stock will consist of 200 NMR tubes.

Patents

Frequency Stabilized Laser

R. B. Green, R. A. Keller, G. G. Luther, P. K. Schenck, and

J. C. Travis

January 15, 1980

U. S. Patent 4,184,127
Sponsored Conferences

Regional Workshop on Corrosion Resources Panel for Managers

of Regional Economic Development—Coastal Zone—Georgia to New Jersey

Wallops Island, Virginia

June 20, 1980

J. Kruger

Gordon Research Conference: High Temperature Chemistry

Plymouth, New Hampshire

August 4-8, 1980

J. W. Hastie

Ceramics as Archeological Material

Smithsonian Institution and NBS, Washington, DC

September 29-0ctober 1, 1980

A. D. Franklin and J. 01 i
.

’

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FRACTURE AND DEFORMATION DIVISION

Richard P. Reed, Acting Chief

Sheldon M. Wiederhorn, Deputy Chief

D. C. Shields, Administrative Assistant

C. J. Montgomery, Secretary

P. L. Sal pi no, Secretary

D. L. Mills, 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. Our Nation pays a high cost because materials fracture;

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 principal goal of the Fracture and Deformation Division

is to minimize material failure.

There are three essential research thrusts to reduce material

failure (1) theory and modeling of deformation and fracture, (2) mechanical

characterization, and (3) fracture-mechanics development and application.

For comprehensive insight, the mechanisms of deformation and fracture

must be understood. Characterization of material mechanical performance

is essential for the proper development and selection of materials for

service application and for efficient design that takes full advantage

of the performance of the selected materials. Fracture-mechanics development

and utilization will provide quantitative assessment and standards for

the integrity of critical structures by relating material mechanical

behavior to flaw characterization and service environment. The emphasis

of the research of the Fracture and Deformation Division focuses on the

critical areas of these three thrusts. This emphasis is subsequently

referred to as Tasks, which are discussed in this report.

The Division is conducting a study to assess the costs of fracture

to the Nation. This study was mandated by the Congressional 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, it sometimes happens that structures, mechanical components, and containers experience unintended

fracture during use. The economic effect of unintended fractures and

the costs to prevent fractures are expected to be large in the domestic

economy. The documentation of these costs is one purpose of this study.

A second purpose is to determine the economic benefits to be derived

from wider application of existing fracture-control technology. The

third purpose is to establish the economic impact of the utilization of

improved understanding of fracture processes and the control of fracture

and to identify specific areas requiring research emphasis.

qo

d
Division personnel are located in both Boulder and Gaithersburg.

Although separate geographically, these two groups complement each

other. The Boulder group has emphasized low- temperature properties,

especially mechanical, of metals, alloys, and composites. The Gaithersburg

group has emphasized high- temperature mechanical properties, especially

of ceramics, and failure analyses. Together these groups represent most

of NBS's expertise in mechanical properties and all its expertise in

fracture mechanics, a research activity now expanding at NBS.

The Division's technical outputs reach many government agencies,

including the National Aeronautics and Space Administration (NASA) and

the Departments of Energy (DOE), Transportation(DOT) , and Defense (DOD).

Recent emphasis on fusion, magnetohydrodynamics (MHD), coal gasification, and geothermal energy by the Department of Energy has led to

several efforts: low-temperature research for structural containment of

the large magnetic fields produced by superconducting magnets; an assessment

of future low-temperature material requirements for superconducting MHD

magnets; characterization of castable refractories at high temperatures

and pressures; development of an j_n situ evaluation test for metal

susceptibility to high- temperature, high-pressure environment-assisted

metal cracking; property characterization of geothermal cements; and

study of high-temperature deformation and crack growth of coal -conversionsystem structural ceramics. Transportation-related research includes

establishing inspection and alternative allowable-defect-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 standards for

lightweight compressed gas cylinders, and numerous structural metal -fracture

analyses. Research for the Department of Defense is diverse. We assist

the Navy in upgrading its fracture-control plans, identifying material

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, and examination

of the low- temperature material properties related to superconducting

motors and generators for ship propulsion. We assist the Air Force in

using advanced composites in lightweight-superconducting-magnet, airborne

power packages. The creep, fracture toughness, strength, and elastic

properties of several alkali halides are being studied to assist NASA in

proper selection of the scintillation material for the NASA Gamma Ray

Laboratory.

The Division hosts and leads a number of workshops and conferences

each year. Collaborating with the DOE, annual workshops on "Materials

at Low Temperatures" are hosted each year at Vail, Colorado. The Mechanical Failure Prevention Group hosted two conferences: "Failure Prevention in Ground Transportation Systems" and "Failure Prevention in

Pipelines." With the American Welding Society our Division cosponsored

the conference on "Fitness-for-Service of Welded Structures." The

Division actively leads and supports the International Cryogenic Materials

Conference, which held its annual meeting in Geneva, Switzerland, on "Nonmetal lie Materials at Low Temperatures."

ICO
New opportunities for research have been provided in the Division

by the NBS Durability Program. Increased emphasis has been placed

on elastic-plastic fracture mechanics. Workmanship codes need to be

extended to fitness-for-service alternatives to reduce repair welds, to

assess specific defects in critical structures, to formulate fracture-control

plans for critical structures, and to estimate structural -integrity

lifetimes. Elastic-plastic fracture-mechanics models and methodologies

are needed to replace the traditional linear-elastic fracture-mechanics

approach because most structural alloys for critical applications are selected to ensure against crack instability preceding plastic deformation.

Therefore, research has been initiated on test methodologies, model

development and verification, and effects of defects and subcritical

crack growth; all of these relate to elastic-plastic or all-plastic

conditions.

New studies have also been started on high- temperature or time-dependent

properties of metals. Such research is timely because new energy-conversion

systems, plasma-containment systems, and nuclear systems all have serious

material -selection and durability problems associated with understanding

and characterizing the time-dependent fracture processes in structural

alloys. Study of crack-tip fracture mechanisms, characterization of

fracture processes, and generation of property data (emphasizing creep

and fatigue), will provide new insights to assist in high-temperature

design and material selection.

Three principal research tasks have been established to emphasize

the research directions Division:

12121 FRACTURE MECHANISMS AND ANALYSES

12122 DURABILITY OF CERAMICS AND COMPOSITES

12123 ELASTIC-PLASTIC FRACTURE MECHANICS

Research within our Division is discussed under Subtasks of these.

Tasks 1 and 3 have received greater emphasis from the opportunities

under the Materials Durability Program, and Task 2 emphasizes research

directed toward mechanical performance of the very promising major

material classes: ceramics and composites.

FRACTURE MECHANISMS AND ANALYSES

Task 12121

For structural materials, the basics of crack-tip processes are essential to understanding fracture and predicting its long-term effects.

Influences of atomic structure and chemical reactions at the crack- tip

have been demonstrated with atomistic models of fracture in a solid, but

these influences have not yet been confirmed quantitatively by experimental studies of subcritical crack growth and environmental effects.

Ductile processes in the high-stress region of the crack tip must be

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 fatigue. High-temperature fracture is complex:

competitive fracture mechanisms, such as subcritical crack growth,

cavity nucleation and growth, and grain-boundary sliding, are 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 maintaining

a Failure Information Center, our Division serves as a focal point for

analyses and compilation of many critical structural failures.

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 time-dependent conditions

will be increased by research on crack- tip theory coupled with high- temperature

tensile, creep, and fatigue properties.

Research in Fracture Mechanisms and Analyses is divided into five

areas: Fracture Theory, Time-Dependent Fracture Processes, Failure

Information Center, Failure-Avoidance Services, and Plastic Deformation

of Metals.

Fracture Theory

Subtask 1 of Task 12121

T.-J. Chuang, R. deWit, R. J. Fields, E. R. Fuller, Jr., R. M. Thomson,

S. M. Wiederhorn

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. This desire for understanding

at a fundamental level has provided considerable impetus to atomistic

modeling of cracks and crack-tip processes. By reconsideri ng a one-dimensional

lattice model of a crack, we were able to decouple effectively the

nonlinear interatomic interactions in the crack-tip region from the

linear elastic interactions in the bulk solid. This stratagem provides

a mechanics model within which the influence of the crack-tip bona

interaction can be explored, whether that interaction is intrinsic or

103

4
chemically affected. Utilizing a Green 1 s-function approach and the

method of lattice statics, this analysis has been extended to more realistic crack configurations in two- and three-dimensional cubic

lattices. The concept of partitioning the fracture phenomenon into two

parts, one specific to the crack- tip region and another specific to the

bulk elastic solid, remains as a general feature in these more realistic

configurations.

Although these atomistic models demonstrate the existence of stressdependent energy barriers to crack advance, and illustrate the influence

of chemical interactions on these barriers, they do not address the

kinetics of crack growth. To address this issue, kinetic theories of

chemically assisted fracture were developed at two levels of sophistication. Both theories are couched in terms of classical "absolute reaction

rate theory," but one represents a statistical -mechanical approach to

fracture whereas the other represents an extension of chemical -reactionrate theory. For the stati stical -mechanical approach, expressions were derived for the crack-growth rate in a reactive gaseous environment.

Specific results depend on the chemical system studied including both

solid and gaseous species. But in general, atmospherically assisted

fracture is associated with a reduction in the surface energy due to

adsorption. The chemical approach agrees conceptually with the statistical

mechanical approach, but treats the solid as an elastic continuum and

the bond rupture process at the crack tip as a chemical reaction. A

basic equation from chemical reaction rate theory was extended to account

for both the high tensile stress fields and the highly curved surfaces

in the crack-tip region. When compared with experimental data for

silicate glasses, this expression gives a crack growth rate that is

proportional to the chemical activity of the reacting species, predicts

a stress dependence in agreement with activation volumes, and gives an activation energy in agreement with silica-network dissolution data.

At lower temperatures, failure results primarily from chemically

assisted subcritical crack growth. As the temperature increases, however,

creep deformation and creep crack growth become important elements of

the high- temperature failure process. With the initiation of experimental

studies in this area, we have begun to consider models of crack growth

in a creeping material. When the creep behavior is localized to the

crack-tip region, a strain-rate dependent zone correction (analogous to

the plastic zone correction used by Irwin for small scale yielding)

adequately describes the strain-rate dependence of the high-temperature

toughness. When the creep behavior is not localized, however, a more detailed account must be taken of the influence of time-dependent deformation on the fracture process. In this regard we have reviewed two

recent manuscripts on this subject (one by C. Y. Hui and H. Riedel, and

another by E. W. Hart), and are pursuing the nature of apparent discrepanci

in their results.

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 year, 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-intensity factor change, and thereby displays

the variety of ways that cracks can grow in a material. We have used

these crack-growth-mechanism maps as an aid in the critical evaluation

of elevated-temperature 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 is missing or is

contradictory. These maps have been prepared for a number of materials

including a nickel -base superalloy, an aluminum alloy, a hot-pressed

silicon nitride, and a number of silicate glasses.

Time-Dependent Fracture Processes

Subtask 2 of Task 12121

B. W. Christ, J. G. Early, R. deWit, R. J. Fields, S. W. Freiman,

E. R. Fuller, Jr., G. E. Hicho, C. G. Interrante, R. S. Polvani,

S. R. Low

Crack growth experiments are being conducted in controlled atmospheres

to provide experimental corroboration with our atomistic theories of

chemically assisted crack growth. An optimum selection of material,

environment, and temperature is necessary to ensure chemical absorption

at the crack tip and yet to prevent complications that result from

crack-tip dislocation processes. Accordingly, initial experiments have

been directed towards characterizing the crack growth behavior of a soda-lime-silicate glass as a function of temperature in vacuum and in

gaseous environments of argon and argon with two percent hydrogen.

Since chemically assisted crack growth in this material is generally

attributed to the presence of water vapor, these experiments will help

to clarify the role, if any, of hydrogen. Further studies will be

conducted on two materials: fused silica, a material that exhibits

moisture-assisted crack growth, but does not exhibit crack growth in

vacuum; and single crystal silicon, a material that does not appear to

exhibit any type of subcritical crack growth.

Another area of time-dependent response that we have begun to

examine this year is creep-assisted crack growth at high temperature.

As part of this effort we have been characterizing the creep-cavitation

behavior ahead of a growing crack in copper and in a high-temperature

structural alloy. Either a center-cracked panel or a single-edge-notched

tensile specimen is subjected to an applied load at elevated temperature

to extend the crack by creep-crack growth. The distribution of cavities

around the crack tip is then character!' zed using automated quantitative

metal lographic techniques. These studies will help to provide an understanding both of the creep cavitation behavior in the highly nonuniform

stress field ahead of a crack and of how these cavities contribute to the

crack-growth process.
In another area of research, a comparison is being made among

various methods for determining the amount of high-temperature crack

growth. For this purpose, compact tension specimens of an aluminum

alloy have been prepared and heat treated to fracture in a creep-brittle

manner. Five methods are being considered for measuring the extent of

crack growth: (1) a compliance technique; (2) an electrical resistance

technique; (3) a crack-mouth-opening-displacement measurement; (4) a visual measurement on the side of the specimen; and (5) an actual cracklength measurement by sectioning through the thickness. Ultimately,

these techniques will be applied to high- temperature crack growth in a high-chromium ferritic stainless steel.

An objective of this subtask is to investigate and improve test

methods in two generic categories: (1) those that are used in studies

of fracture processes that are governed by an environmental effect on a material under sustained loading conditions and (2) those that may be

influenced by a strain-rate sensitivity of the material of test. As a counterpart to this objective, these methods are applied to significant

materials problems.

In the area of sustained load testing, the problem of hydrogen

embrittlement of steels has been a focus of studies. As a result of

past efforts, studies have been published on (1) a method for measurement

of the permeation of hydrogen in metals, (2) a method for removal of

sulfides from fracture surfaces that have been exposed to aqueous sulfide

environments, and (3) studies of the effect of temper embrittlement of

steel on the susceptibility of steel to hydrogen embrittlement.

This year, attention has been centered on completing work on development

of an automated real-time method of analysis of crack-growth rates of

steels tested in aggressive aqueous environments. This method has been

applied to study the behavior of 2.25 CR - 1.0 Mo steels tested in an acetic solution containing H 2 S at one atmosphere of pressure, using the

double cantilever beam (DCB) type of fracture-mechanics test specimen

using the test methods and data acquisition system that were developed

in these studies. Crack-growth-rate data were obtained for various

conditions of test to determine the effects of specimen orientation,

methods of specimen preparation, and steel hardness. Work is underway

on the development of a suitable test method to assess environmental

conditions that promote the formation of branch cracks in DCB specimens

tested in a severe sulfide environment. These studies have been con- ducted 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 in about a year

from now as a WRC Bulletin on The Effects of Hydrogen on Pressure Vessel

Steels was initiated this summer.

Impact- test studies have been centered on the measurement of fracture toughness using both pendulum and drop-weight tests. Pendulum

testing includes tests of both standard and precracked Charpy-V-notch

(CVN) specimens. Drop-weight testing includes dynamic-tear (DT) tests

and drop-weight NDT tests. Test-method development activities have
involved methods for computer-assisted testing and data analysis for

these impact tests. The studies include 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,

structural steels used in highway bridges, and plate materials used in

pipelines. The results of impact tests are often useful for fracture

control, based upon either service experience or empirical correlations

with fracture-mechanics tests.

Failure Information Center

Subtask 3 of Task 12121

R. C. Dobbyn, W. A. Willard

The Failure Information 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, 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 Failure Information

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 500 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.

Although fewer pilot plants are now operating, resulting in a very

slow rate of increase of the data file, there is continuing interest on the part of the user community. Some 1100 reports and about 30 data

tables and abstracts summarizing in-service materials and components

performance were sent out in response to over two dozen requests. An

107
interpretive report, analyzing erosive wear failures, has been published

as an NBS internal report and has also been submitted to DOE for publication in their report series. Information is regularly supplied for

the Failure Experiences feature of the DOE Materials and Components

Newsletter , published by Battelle-Col umbus.

The major effort for the past year has been a joint project with

the Materials Properties Data Center in the preparation of a publication, Construction Materials for Coal Gasification--Performance and

Properties Data , currently submitted to DOE for approval. This book

contains information gained in practical plant experience and also the

results of materials research and 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 extended data for the chemical, physical, and mechanical

properties of the candidate materials. The book will consist of loose-leaf

pages so that increasing and revising the data can be done readily on a regular basis.

Failure-Avoidance Services

Subtask 4 of Task 12121

J. H. Smith, J. G. Early, T. R. Shives, G. E. Hicho, W. A. Willard,

B. W. Christ, C. G. Interrante

Failure-avoidance services provided to other Government agencies

and other Divisions within NBS include diagnostic failure analysis,

mechanical-properties testing, metall ographic analysis, and metallurgical consultation. The results of this work have been used to assist

in the development of safety regulations, in the selection of improved

materials to improve the reliability of components and structures, and

the development of improved test methods and standards. In many cases,

diagnostic failure analysis of failed components has led to the identification of needed research in materials characterization and this

research is now part of the ongoing programs described in this report.

During the present year, some 30 reports of specific projects in failure

analysis and failure avoidance have been completed. As in previous

years, projects have been completed for the National Transportation

Safety Board, the Consumer Product Safety Commission, the Bureau of

Engraving and Printing, the Federal Railroad Administration, and the

Office of Hazardous Materials. Also, special projects were completed

for eight other Federal agencies. Reports of these investigations are shown in the list of publications in this report.

Diagnostic failure investigations for the National Transportati on Safety Board (NTSB) were completed on several aircraft components and on several sections of failed gas pipeline. The results of these investigations

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.

it:
Investigations for the Consumer Product Safety Commission (CPSC)

included analysis of bicycles, lawn mowers, hardware items, and copper

tubing. The results of these investigations are used by CPSC to assess

the need for modifications to the design or materials used in these

products to reduce the risk of injury to the public.

Continuing work for the Bureau of Engraving and Printing (BEP) has

successfully identified the cause of failure in printing plates and other

components in the presses used to print money and postage stamps. The

results of these investigations have resulted in improved specifications

for purchasing the materials and fabricating these components so that

failures in the BEP printing presses have been essentially eliminated.

Recent investigations on several metallic components used for

implantation during surgery have been completed for the Food and Drug

Administration. Identification of the cause of premature failure in

these components is essential to improving the reliability of these com- ponents.

A major investigation to identify the cause of cracking in welds in

the replacement Silver Bridge at Point Pleasant, West Virginia, has been

completed for the Federal Highway Administration. The results of this

investigation will be used by the Federal Highway Administration to

specify materials requirements, welding procedures, and weld-repair

procedures to be used in future bridge construction. Weld cracking has

been identified as a problem in several large bridges recently constructed

throughout the interstate highway system. Identification of the causes

of these cracks and the specification of corrective measures .is an urgent national problem.

Continuing work for the Federal Railroad Administration has identified the causes of failure in railway tank cars and in suggesting improved

materials to resist fracture in the event of tank-car accidents. 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 which significantly

reduce the frequency of major tank-car accidents.

Besides these major failure-analysis investigations, a wide range

of other projects was completed. Determination of the cause of failure

in several types of fasteners was completed for the Coast Guard, the

Navy, and the National Oceanic and Atmospheric Administration. 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 regulations are required.

For the Department of Justice, an investigation of the mechanical properties and strength of fencing used along the U.S. and Mexican border

was completed. The results of this investigation may be used to develop

more suitable specifications for the procurement of this fencing.

IDS
The dissemination of information to assist in Failure Avoidance was continued by NBS sponsorship of two meetings of the Mechanical Failures

Prevention Group (MFPG) and the publication of the proceedings of these

meetings. A meeting with the theme "Advanced Composites--Oesign and

Application" was held in October 1979 and emphasized the use of new composites and identified means to prevent failure and improve the

durability of components made from composites by proper design, materials

selection, and inspection. The April 1980 meeting of the MFPG was on "Ground Transportation Systems" and provided a forum for discussion of

methods of failure avoidance in bridges, pipelines, automobiles, and

railway equipment.

Plastic Deformation of Metals

Subtask 5 of Task 12121

B. W. Christ, R. S. Polvani

Tensile microcreep in various metals and alloys is being measured

currently on instrument-grade beryllium. The overall goals of this

study are: (1) to develop a data base on microcreep (10 12 cm/cm-s) for

improved design of gyroscopes used in inertial-guidance systems for naval

applications, and (2) to develop a fundamental understanding of microcreep.

This program involves combined efforts of two NBS groups and the C. S. Draper

Laboratory, Cambridge, Massachusetts.

Microcreep testing of i nstrument-grade beryllium has been carried

out at about 63 °C (145 °F). Temperature control is held to ± 0.005 °C

(0.01_°F) on two testing systems designed to detect strains in the range

of 10 7

. _A third testing system designed to detect strains in the

range, 10 8

, operates at a temperature of 40 °C (104 °F) with temperature

control of ± 0.001 °C (0.0018 °F). Testing methodology is being developed

to promote alignment control for microcreep tests in the stress range,

0.689 to 6.89 MN/m2 (100 to 1000 psi) microstrain hardening, as well as microcreep rates, is of interest. A testing system for measuring microcreep rates under biaxial loading has been designed and built.

Initial results show that 1-400 grade beryllium exhibits a microstrain of about 4 x 10 6 in 1000 hours at a stress of 20.67 MN/m2 (3000 psi).

The predominant deformation mechanism seems to be dislocation glide.

no
DURABILITY OF CERAMICS AND COMPOSITES

Task 12122

The Fracture and Deformation Division program on ceramics and

composites has as its objectives five separate goals: (1) generation of new theory and data to elucidate fracture and deformation mechanisms in

nonmetallic materials; (2) development of new techniques for studying

the fracture and deformation properties of materials; (3) collection of

engineering data for structural applications; (4) investigation of

degradation processes that result in erosive and abrasive wear of non- metallic materials; and (5) investigation of the microstructure of non- metallic materials and their relationship to mechanical behavior.

Experimental techniques developed by the Division permit measurements on the mechanical properties of composites and ceramics over a wide range

of conditions: in vacuum at temperatures to 2700 °C in corrosive environments at temperatures that range from room temperature to 1600 °C, and

in cryogenic environments at temperatures as low as -269 °C. This range

of experimental capabilities is unique.

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. Ceramics, such as glasses, refractory concretes, geothermal

cements, porcelains, and high-density ceramics, are used in many commercial

applications, for example: 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 the coal-conversion and petrochemical

industries. In defense applications, these materials are used as radomes,

missile nose cones, turbine components in portable electric-generating

facilities, and bearing surfaces in gyroscopes. Because they are brittle,

structural ceramics are usually overdesigned to satisfy engineering

requirements, or are not used, even though they have other outstanding

properties. The investigation of the fracture and deformation properties

of these materials may overcome many of the difficulties associated with

their brittle behavior and permit ceramics to be used more effectively.

In contrast to metals or ceramics, composite materials are highly

engineered, heterogeneous materials designed to impart unique, superior

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 normal grades of steel. Extensive commercialization of composites will realize major energy and materials savings,

increased productivity, improved product safety, and improved U.S.

technological innovative capabilities. The solution to effective industrial utilization of composite materials is a better understanding of

their wear-out and fracture mechanisms. By investigating the mechanical

strength and fracture behavior of a variety of composite materials

(ceramic/ceramic, ceramic/metal, cerami c/polymer , and metal /polymer)

,
many of the problems associated with mechanical degradation will be

solved, and composites will be used in a wide variety of industrial

applications for their unique properties.

Fundamentals of Fracture

Subtask 1 of Task 12122

S. W. Freiman, T. A. Michalske, E. R. Fuller, Jr., S. M. Wiederhorn

Studies are conducted to elucidate basic mechanisms of fracture and

deformation in ceramic and composite materials. Because water plays

such a dominant role in the stress corrosion of ceramic materials, most

of the work during the past year was directed at understanding the role

of water in the fracture process. The program is multifaceted, applying

a variety of experimental techniques to this problem. Fracture-mechanics

techniques and strength studies are used to understand the role of glass

composition on the fracture process, whereas electron spectroscopy

(chemical analysis) and Raman spectroscopy are used to identify the

corrosion species and to investigate the effect of stress on the structure

of ceramics. The program is approximately a three-man-year/year effort

and involves collaboration between the Fracture and Deformation Division,

and the Ceramics, Glass, and Solid State Science Division, and between

our Division and Howard University. Details of this program are given

bel ow.

Surface Analysis : A new analytical technique, electron spectroscopy

for chemical analysis (ESCA)*, is being applied to analyze chemical

species that are formed on fresh surfaces of ceramic materials. Preliminary experiments were conducted during the past year on titanium to

gain experience in using the ESCA apparatus and the NBS-designed deposition system for laying down thin coats of ceramic or metallic materials.

Experiments consisted of the deposition and subsequent oxidation of

metallic titanium. The oxidation process was analyzed using both 90°

and angle-resolved ESCA. Studies showed that although oxidation occurred

throughout the titanium, it occurred preferentially near the surface, as expected. The difference between surface and bulk oxygen in thin films

was readily identified by peak shifts in the spectra using angle-resolved

ESCA. Unfortunately, the effect of stress on the oxidation process

could not be readily determined using the equipment as currently designed;

consequently, the surface-analysis system is being modified to allow

angle-resolved ESCA spectra to be obtained on stressed specimens.

Once these preliminary experiments are complete, and the equipment

is operating satisfactorily, studies of water adsorption on ceramic

substrates will be conducted. The effect of stress on the adsorption

process will be studied by comparing the ESCA spectra obtained from thin

films that are subjected to tensile stress with spectra obtained from

stress-free films. To obtain such data, a tensile stage has been con- structed that is capable of applying a stress to a thin film while it is

being examined by the surface-analysi s equipment. An apparatus was also

constructed, with the help of the Surface Science Division, to admit

precise amounts of water into the vacuum chamber for adsorption studies.

112
Within the coming year, we hope to use this apparatus for chemical

analysis of stressed ceramics and glasses. This project is being con- ducted jointly with the Ceramics, Glass, and Solid State Science Division

(D. M. Sanders).

Raman Spectroscopy : Raman-spectroscopy studies were conducted on fused silica fibers in order to determine the effect of stress on the

structure of silica glass. It was observed that there were significant

changes in peaks associated with defects in the Si02 structure under

stresses of 2.1 to 3.4 GPa (300 to 500 ksi). These peaks were reproducible

and have been ascribed to stretching of Si-0 bonds. A talk on this work

was presented at the annual meeting of the American Ceramic Society, and

has now been written (S. W. Freiman, G. Walrafen, and P. N. Krishnan)

and submitted for publication.

Crack-Growth Studies in Corrosive Environments : To investigate the

relationship between corrosion of materials and subcritical crack growth,

experiments were studied on several glasses in aqueous environments.

The glasses varied greatly in their resistance to corrosion: chemical

borosilicate glass and soda-lime-silica glass being the most durable;

binary soda-silica compositions being the least durable. The effect of

ion exchange on the crack growth process was investigated by conducting

crack-growth studies in aqueous solutions containing either lithium or cesium ions. No significant effect of these ions on crack growth in the

durable glasses was observed. By contrast, these ions had significant

effects on crack propagation in the soda-silica glasses. The slope of

the voltage-stress intensity (V-Kj) data was considerably greater when

tests were conducted in solutions containing lithium ions. Perhaps the

most significant observation was the existence of a low velocity (10 8 to 10 10 m/s) plateau for the soda-silica glasses. This plateau has

been attributed to crack-tip blunting, and its existence confirms the

theory of stress-corrosion cracking developed by Charles and Hillig.

Crack Growth in Phase-Separated Glasses : Crack growth experiments

were also carried out in phase separated sodium borosilicate glasses

that had been heat treated to vary the size and chemical composition of

the phase-separated regions. It was observed that the V-Kj curves

shifted to lower stress intensities as the heat- treatment time and the

microstructure size increased. This behavior was interpreted in terms

of the decrease of the chemical durability of the silica-rich phase due

to an increase in Na2 0 content of this phase. It was concluded that the

microstructure size had little or no effect on crack growth since the

crack always intersects both phases in the interconnected microstructure.

Proof Testing : To evaluate the effect of multi region crack growth

on component reliability after proof testing, soda-1 ime-sil ica glass was used as a model material in a set of proof- test studies that was conducted

in normal pentane. Normal pentane was used to magnify the effect of

multi region crack growth because of the rather broad region- II crack-growth

behavior in this liquid. Results were compared with a detailed theory

of proof testing developed during the previous year's work; modest

113
agreement between theory and experiment was obtained. The results from

this study indicate that proof testing should be conducted in a dry

gaseous environment using a rapid rate of unloading from the proof test

load. If this procedure is not followed, a substantial number of com- ponents are liable to fail at loads that are less than the proof-test

1 oad.

New Approaches to Fracture and Deformation Information

Subtask 2 of Task 12122

E. R. Fuller, Jr., S. W. Freiman, S. M. Wiederhorn, R. J. Fields,

N. J. Tighe

The techniques of fracture mechanics provide engineers with new methods for estimating the total allowable lifetime under load when

mechanisms of failure are well understood. For ceramic materials, the

primary mechanism of failure at low temperatures is subcritical crack

growth, whereas that occurring at high temperatures is creep and creep

cracking. By characterizing creep and fracture processes in ceramic

materials, estimates of the creep rate or the crack-growth rate can be

made, and the lifetime of structural components can be determined. The success of this approach depends, in part, on the quality of the creep

and crack-growth data used to characterize the fatigue behavior.

For creep experiments pneumatic loading is being substituted for

dead-weight loading. The pneumatic system has several advantages over

the dead-weight system. It is inexpensive and compact; a number of

systems can be used simultaneously for experimental purposes without

requiring a great deal of space for operations. In addition, since

compressed air is used to transmit load to components, the test system

has a low inertial mass and is therefore insensitive to shocks or vibrations that may be present in the laboratory. Consequently several test

fixtures can be mounted in a single furnace to conduct strength experiments without fear of interference between the separate fixtures. These

advantages were used in the construction of a high temperature fracturemechanics facility, which was designed so that three loading fixtures

can be operated in each furnace. A similar facility is now nearing

completion for evaluating the creep resistance of refractory materials

for regenerative heat exchangers in large MHD facilities.

A pneumatic-loading facility has also been constructed as an integral

part of our bioceramic test program. Here the compactness of the system

has an advantage for the construction of a multiple- test facility that

has the proper biological environment for testing materials intended for

use as prosthetic devices. The equipment for the bioceramic program

will be monitored through the use of a computer. The computer will

automatically monitor the load, time under load, and temperature of the

experiment, and will store these parameters until requested by the

operator.
Two techniques for analyzing strength data in terms of fracturemechanics parameters have been developed. An analysis was developed to

determine crack-growth rates from static-fatigue (i.e. , sustained-load)

data. It is straightforward to calculate the time-to-fai 1 ure at a given

applied-stress level if the nucleation and crack-growth behavior are

known. The inverse analysis is not straightforward. This inverse

analysis was developed under the assumption that nucleation times are negligible and that failure times at stress are determined solely from

crack-growth behavior. The analysis gives excellent agreement with

measured data for a soda- lime silica glass.

In the second technique, the four-point bend test was analyzed to

obtain crack-velocity data as a function of linear stress- i ntensi ty

factor from a load-displacement curve. In a linear elastic material the

load should be linear with displacement. If this is not the case (e.g.

,

ceramics at elevated temperatures) then either the crack has grown,

changing the specimen compliance, or the specimen has deformed plastically. Considering these possibilities for high-temperature structural

ceramics, sensitive measurements were performed on hot-pressed silicon

nitride at 1200 °C. Less than one percent permanent strain was detected

in this material in the region of the final fracture. Therefore it was concluded that the nonlinear load-displacement curves were due to crack

growth and the concomitant change in compliance. Consequently the

compliance was calculated as a function of crack length for the fourpoint bend test. Using the calculated expression, the crack velocity

and stress-intensity factor can be determined at any point on the

load-displacement curve even when the stress-intensity factor is

changing rapidly. It is possible to use this analysis to measure

transient phenomena as well as steady-state phenomena that occur during

crack growth. This technique of analysis provides a new means of collecting data on materials that exhibit crack-growth behavior at elevated

temperatures.

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, D. E. Roberts, C. L. McDaniel, R. F. Krause, Jr.,

G. E. Hicho

Extensive studies are being conducted on the strength of ceramic

materials that are intended for use in a number of important commercial

and defense applications. Materials being studied include: geothermal

cements that will be used to line the wells that tap hot reservoirs of

water deep within the earth, specialty ceramics that are intended for

use in heat engines, dense ceramic materials for prosthetic devices,

alkali halides for scintillation counters in deep-space NASA gamma-ray

observatories, dielectric materials for ceramic capacitors intended for

defense applications, and refractories for regenerative heat exchangers

used in MHD applications.
Geothermal Cements : The program on geothermal cements was initiated

to develop a laboratory test facility for screening candidate cementing

materials that are to be used in finishing operations of geothermal well

holes. The program provides the technical data necessary for an evaluation of the structural integrity of these cements after they have been

exposed to high-pressure, high-temperature brine. The suitability of

these cements for more costly tests in down-hole facilities will be

evaluated for DOE. The program is divided into several tasks aimed at

establishing the mechanical and physical properties of cements after

they have been exposed to simulated geothermal environments. Properties

include flexural and compressive strengths, strengths of cement pipe

interfaces, and cement permeability at high pressures and temperatures.

The equipment has been designed and built. Proposed procedures have

been drafted and submitted to an American Petroleum Institute Task Group

for evaluation. In response to the DOE program for the development of

improved cements, other laboratories have submitted 22 cement formulations

for examination. Measurements have been made of the compressive strength

and tensile strength of the cements, of the shear-bond strength of the

cement to steel, and of the permeability of cement to water. In a cooperative venture established with Los Alamos Scientific Laboratory,

portions of all the cements involved in the exposure studies were forwarded to Dr. G. Cocks of the DOE Los Alamos Laboratories for microscopic examination.

High-Temperature Structural Ceramics : Because ceramic materials

offer the potential for significant increases in operating temperature

and efficiency for gas turbine engines, silicon nitride and silicon

carbide are being considered by DOD and DOE for application in heat

engines. The division is contributing to these programs by evaluating

the applicability of proof testing as a method of ensuring the structural reliability of heat-engine components, and by studying the mechanisms

by which these materials fail at elevated temperatures.

The objectives of the program on proof-testing are three-fold:

(1) investigate long-term effects of high temperature on the strength of

silicon carbide and silicon nitride; (2) determine the physical and

chemical conditions that limit the applicability of proof-testi ng as a method of improving the reliability of these ceramics; and (3) characterize the conditions of environment and temperature that result in

strength- impai ring flaw generation in silicon nitride and silicon carbide.

It is expected that this program will provide a base of experimental data

upon which a modified theory of component reliability can be built.

To date, approximately 1500 specimens of various commercial grades

of silicon carbide and silicon nitride have been tested. Strength tests were run at 1200 °C for exposure times as long as 1000 hours, on sets of

specimens that were either load free, or subjected to an applied load

during exposure. The study demonstrates a wide variability in the

behavior of these materials, the variability depending on the type of

material, the process used for manufacture, and the particular lot or billet from which the material was derived. Despite the variability in

the data, certain trends were ODserved that suggest a course of action

for modification of theories of component reliability.
At one extreme of behavior, reaction-bonded silicon nitride became

stronger with exposure to air at 1200 °C. Specimens that were subjected

to an applied load either failed immediately, or survived the entire

1000-hour exposure without failing, suggesting that delayed failure does

not occur in this material. The strength of the survivors greatly

exceeded the strength of specimens tested without high- temperature

exposure. This result suggests that higher temperatures modify the flaw

structure of the material to improve the mechanical properties.

At the opposite extreme of behavior, hot-pressed silicon nitride

exhibited delayed failure during the entire course of exposure for 1000

hours. Specimens that survived the 1000 hours exposure, however, were

significantly stronger than those that had not been exposed to 1200 °C.

Studies on specimens that were intentionally flawed by the use of a hardness indentation to form surface cracks indicate that crack healing

occurs as a result of high-temperature exposure, so that the delayed

failure that was observed cannot be attributed to machining damage, or

to other flaws that were originally present in the specimen surface.

Delayed failure was probably due to flaws that were generated as a consequence of high-temperature exposure. These results suggest that

any theory of reliability developed to explain the high-temperature

behavior of structural ceramics must take into account flaw generation,

flaw healing, and crack growth.

Based on these experimental results, a theory of lifetime prediction has been developed for structural ceramics. The theory was presented at the Sixth AMMRC Materials and Technology Conference, "Ceramics

for High Performance Appl ications--III" held at Orcas Island, Washington,

(proceedings available as an NBS report, NBSIR 80-2024, May 1980). The

theory accounts for the combined processes of flaw healing, pit formation, and subcritical crack growth. The theory independently evaluates

these three processes and then determines the relative contribution of

each of these processes to the total failure time. Conditions are established for proof testing of as-received components. Because of the

occurrence of pit formation in hot-pressed silicon nitride, a maximum

value for the proof-test load is established, above which proof testing

does not contribute to component reliability. After long-term exposure,

proof testing or nondestructive evaluation can be applied again if the

flaw (pit) distribution has reached static equilibrium. If, however,

the flaw distribution has reached a state of dynamic equilibrium, then

statistical techniques must be applied for lifetime prediction. Assuming

that the strength distribution of pits can be represented by a two-parameter

Weibull distribution, statistics can be used for the combined failure

modes of pit formation and crack growth. For these conditions, equations

are developed for determining the total failure time.

Success of this theory requires detailed information on the modes

of failure that may be operating in structural ceramics. Therefore, the

assembly of experimental strength data on structural ceramics and the

collection of microstructural information on these ceramics is vital for

the development of a sound lifetime prediction capability. Since the

modes of failure depend critically on the composition and type of ceramic
being considered, data should be application specific; hence, one needs

experimental data on a wide variety of ceramics exposed to temperatures

and environments that reflect operating conditions. Our program has as its goal the collection of such data, and based on this data, the development

of a viable lifetime prediction theory. If this program is successful,

it will provide the basis for using ceramics in high temperature structural

applications such as heat exchangers, turbines, and combusters.

The second part of the Division's program on structural ceramics is

concerned with evaluating mechanisms of fracture at elevated temperatures. The specific objectives are to characterize high- temperature

deformation and crack-growth and fracture behavior of structural ceramics

that have potential application in coal-conversion systems. To measure

crack velocity as a function of stress-intensity factor, an analysis of

the four-point bend test was made that allowed the crack length, stressintensity factor, and the crack velocity to be calculated from the

points on a load-deflection curve. Hence, a notched, four-point bend

test can be used to yield information on both fracture toughness and

crack velocity as a function of stress intensity for a broad range of

stress-intensity factors.

Materials include yttria-doped silicon nitride, several experimental compositions of silicon nitride with additions of garnet, and

experimental grades of single-phase sialon (Si 5 A10N 7 ) materials. Experimental materials are being supplied by Prof. Tien of the University of

Michigan and by Dr. K. Kobayashi of the National Industrial Research

Institute of Kyushu, Japan. Because of its high toughness and resistance to crack growth, the best grade of material examined so far was the

yttria-doped Si 3 N 4. The garnet-doped compositions of Si 3 N 4 were found

to exhibit severe oxidation at temperatures that exceeded 1300 °C,

suggesting that these compositions cannot be used for structural applications at these temperatures. However, by noting the compositions that

result in the highest toughness, crack-growth resistance, and oxidation

resistance, a systematic approach can be used to develop the optimum

composition for high-temperature structural design. The sialon compositions appear to oxidize rapidly at 1300 °C, probably as a result of

migration of impurities from grain boundaries to the surface of the

solid. Data obtained on this project are being reported to Dr. Tien and

Dr. Kobayashi in order to lend direction to their fabrication efforts.

An important finding is that the fracture toughness of these materials

at elevated temperatures is extremely sensitive to the loading rate.

The fracture toughness of silicon nitride type materials increases

dramatically at a critical value of the loading rate. The maximum

toughness obtained as a function of loading rate depends on the test

temperature. This effect is the result of the time-dependent nature of

the creep strain field that forms around crack tips at elevated temperatures.

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

113
components of prosthetic devices because they are biologically inert to

the body environment and are relatively strong 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.

This year, experimental rigs to perform long-term delayed failure

tests on biomaterials have been completed. The experimental setup

consists of ten pneumatically loaded test fixtures. Specimens are held

in tanks through which selected liquid environments are pumped from a heated container. A computer data acquisition and monitoring system was

installed. Preliminary delayed failure data are being obtained in

distilled water on Friedrichsfeld A1 2 0 3 , which is currently used as a biological implant material. When these studies have been completed,

the fracture of these materials in a more realistic biological environment will be studied.

Materials for the NASA Gamma-Ray Observatory : A new project initiated

during the past year involves the evaluation of the mechanical properties

of alkali halides to be used as scintillation material for the NASA

Gamma-Ray Observatory. CsI(Na) and Nal(Tl) are materials that scintillate; for this reason both are candidates for the crystal of NASA's

Observatory. Because the mechanical properties of both candidates are largely unknown and alleged to be poor, achieving a flyable weight for

the scintillator assembly is a primary design goal. Long-time deformation (creep) is the problem with CsI(Na); while low fracture toughness

is expected to be the problem with a Nal(Tl) crystal assembly. Our goals

are to determine the creep behavior of CsI(Na) and the effect of loading

rate on the strength of Nal(Tl).

The fracture properties of Nal doped with T1 (Polysin) were evaluated

to determine the fracture toughness of this material and to determine

the possibility of stress-corrosion cracking as a cause of material

failure. The critical-stress-intensity factor, K^, of the Polysin was evaluated in a low-humidity chamber using the doubl e-canti 1 ever-beam

technique. Specimens were precracked to provide a starting crack for

the fracture-toughness measurement. Values of K

T ^ (0.45 MPa*m 1 2

) were

surprisingly high considering the low yield strength of this material

and the lower values obtained on CaF (and on other alkali halides which

are harder materials). Calculations of K

T £

from flaw-size measurements

on bend specimens were in good agreement with K^ r determined from the

fracture-mechanics tests, suggesting that the fracture-mechanics value

is the appropriate one for engineering purposes.
Stress-rate studies were conducted to determine the possibility of

stress-corrosion cracking as a failure mechanism in Polysin. Tests were conducted in an environmental chamber in which the humidity could be

controlled to dew point values as low as -43 °C. Accurate control of

the humidity was necessary to prevent dissolution of the test specimens,

which are highly hygroscopic. No effect of humidity was found in any of

the tests conducted in this program. Surpri singly , plastic deformation

affected the fracture properties of this material, causing the strength

of specimens to increase slightly as the loading rate decreased.

In studies of the plastic properties of Csl doped with Na, the

compressive strength was found to be approximately 0.79 MPa (1100 psi),

larger than expected. However, the strength is strongly dependent on both the crystallographic orientation of the test sample and the annealing

condition of the material.

Screening Tests for Ceramic Capacitors : The objective is the

development of screening tests to assess the performance and expected

lifetime of ceramic capacitors. Studies include the use of ultrasonic

signals combined with sophisticated computer-analysis techniques as a means of detecting delaminations and cracks in capacitors, characterization of the microstructure of the ceramic capacitors and measurement

of the susceptibility of the ceramic material in the capacitor to strength

degradation resulting from internal stresses and subcritical crack

growth.

The importance of this project rests on the use of these capacitors

in critical military applications that require high functional reliability,

so that the mechanical and electrical reliability should be ensured to

the highest technically achievable levels. Recent experience indicates

that the chance of capacitor malfunction in military hardware is sufficiently

high as to cause real concern to DOD. Symptoms of malfunction (dielectric

breakdown of the capacitor) often occur after the capacitors have been

installed in components, which results in expensive repair operations

that add significantly to the cost of the military hardware. Furthermore,

since malfunctions often occur some time after installation, the reliability

of operating systems may suffer as a result of capacitor malfunction.

To alleviate these problems, research is being conducted to develop a better understanding of the causes of failure and to develop techniques

to screen out defective capacitors.

During the past year, stress-rate tests were conducted on capacitor

materials in air and synthetic sea water. The strength curves suggest a change in crack-growth mechanism in sea water at the highest loading

rates.

The critical stress intensity factor, K^, was measured using

precracked doubl a-canti 1 ever-beam specimens. The value obtained for

0.8 MPa-m 1 2

, indicated a rather low resistance of the capacitor

material to fracture. Although the value is low compared to other types

of ceramics, such as AI 2 O 3 , it was consistent with values obtained on fine-grained BaTi0 3 , a material commonly used for ceramic capacitors.

120
TEM studies were conducted on both neodymium and bari um-titanate

capacitors to reveal their microstructure. Although considerable difficulty was experienced in sectioning the capacitors for structural examination because of the tendency of these capacitors to fail at the metallicceramic interface, the technique of specimen preparation was mastered,

and the structure was examined. The grain size varied from less than

1 pm to 10 s pm and most grains contained a complex, three-dimensional

domain structure, usually located near the center of the grain. Some

compositions (neodymium titanate) also appeared to contain glass mixed

in with the crystalline structure. Cracks appeared to propagate in a planar fashion and were not observed to interact strongly either with

grain boundaries, or with the grains that were randomly oriented in the

capacitor. A low resistance of the ceramic structure to crack propagation

is suggested and is consistent with the low values of K, r

.

Refractories for MHD Applications : Refractory materials are used

for MHD air preheaters. The high-temperature plasma (2400-2700 °C)

necessary for operable and economically attractive open-cycle MHD power

generation is achievable through the combustion of fossil fuels using

air preheated to about 1500 °C. Such temperatures require the operation

of regenerative heaters at temperatures as high as 1650 °C; the heaters

require refractory materials that are capable of maintaining their

mechanical integrity at this extreme temperature. Creep resistance is one of the primary properties that will determine the ability of refractories to perform adequately as components in regenerative heaters.

Although several types of commercial refractory bricks have been selected

to serve in this application, creep data on these materials are not

available at temperatures exceeding 1500 °C. The objective is to obtain

the necessary data on the high-temperature compressive creep of the

refractories being considered for use in MHD air preheaters and to rank

the proposed refractories in terms of their creep resistance at the

service temperature of 1400 to 1650 °C.

A twelve-station creep apparatus has been designed and constructed

for multiple creep experiments at temperatures as high as 1650 °C in

air. The facility uses the pneumatic loading fixtures described elsewhere in this report. With this apparatus, specimens will be tested

under static load for times up to 1000 hours at constant temperature,

and with temperatures cycling between 1400 °C and 1600 °C. Samples of

refractories used in the Montana State University air preheater apparatus

were tested in compression at constant load and at constant loading rate

at temperatures of 1400, 1500, and 1600 °C. Compressive creep specimens

having a reduced cross-section were made from cores of (1) a chrome-spinel

refractory, (2) a magnesia spinel refractory containing excess MgO, and

(3) a fused-cast, sodium-doped alumina refractory. The dimensional

stability of each material was measured for samples heated 24 hours at

1400, 1500, and 1600 °C. Changes in composition and phase were determined

from x-ray powder diffraction patterns.
Friction and Wear of Ceramics

Subtask 4 of Task 12122

S. M. Wiederhorn, B. J. Hockey, E. R. Fuller, Jr., D. E. Roberts,

R. S. Polvani

Friction and wear are important phenomena that determine the cost

and reliability of precision-ground ceramic parts. Since machining

often accounts for 90 percent of the cost of these parts, a considerable

reduction in cost may be achieved by improving the machining process.

Furthermore, since machining and erosion leave residual damage that

reduces the strength of ceramic components, an understanding of these

processes may lead to improvement in their strength. To achieve these

ends, this project has been initiated to study the friction, wear, and

erosion resistance of commercially important ceramic materials.

During the past year, work on the erosive wear of ceramic materials

was directed toward: (1) completing our collection of data on the wear

of aluminum oxide and silicon nitride, (2) studying the effect of grain

size on wear, (3) clarifying the microstructure of impact craters in

hot-pressed silicon nitride and fine-grain aluminum oxide, and (4) evaluating the dynamic hardness of ceramic materials.

Erosion Measurements : To complete our erosion data on ceramic

materials, the erosion rate of hot-pressed silicon nitride and a new grade of hot-pressed aluminum oxide was measured using 150-pm silicon

carbide particles at room temperature. The results on these materials

were consistent with those obtained earlier.

The erosion rate of aluminum oxide is being measured as a function

of grain size. Starting with fine grain aluminum oxide (2-3 pm) billets,

specimens are being prepared with grain sizes ranging from 3 to 30 pm.

These specimens will be used to determine the presence of a transition

in the erosion rate (similar to that observed for K^) as the grain size

i ncreases.

Microscopy Studies : SEM and TEM were used to examine damage in the

vicinity of hardness indentations placed in hot-pressed silicon nitride,

and hot-pressed aluminum oxide. The effect of the fine grain size

(2 pm) of both of these materials was readily apparent by examining the

indented area with TEM. In contrast to observations on sapphire, or large grain size (~ 30 pm) sintered alunimum oxide, dislocation motion

and crack motion are restrained by the presence of the grain boundaries.

Cracking in the fine-grain (~ 2 pm), hot-pressed aluminum oxide was considerably less than that in the coarse-grain (30 pm) sintered material.

In the hot-pressed silicon nitride, no cracks were observed when the

indented regions were examined by SEM. However, as specimens were thinned for study, by TEM, cracks were observed to propagate from the

indented regions. These observations support our finding that fine-grained

ceramic materials wear much more slowly than coarse-grained materials.
Dynamic Hardness Measurements : Because of the importance of hardness to the nucleation of cracks during erosion, an attempt is being

made to measure the dynamic hardness of ceramic materials. Two approaches

were taken to obtain estimates of the dynamic hardness. The first 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,

and the equipment is being coupled to a computer so that the impact data

can be analyzed efficiently. Experiments will be conducted on large

plates of soda-lime silica glass to obtain a reasonably accurate picture

of the types of forces that are generated during solid-particle erosion.

The second method of measuring the dynamic hardness is based on the

use of an electrically driven hardness indenter to apply loads to specimens

for durations of about 1 ms. An apparatus of this type was built by

Gunasekera and Holloway in 1973 to measure the dynamic hardness of

glass. An electromagnetic driver capable of applying loads in times of

less than 0.1 ms has been obtained. The load will be measured with a high-speed piezoelectric load cell. Displacements during indentation

will be made with an eddy-current sensing device so that the entire

load-displacement curve can be obtained for a single indentation. When

completed, this equipment will represent a considerable advance over the

apparatus used by Gunasekera and Holloway, who did not use a displacement device, and who depended on measurements of field current to determine the load on the sample. We hope to use the equipment to measure

the dynamic hardness of a range of ceramic and metallic materials.

Microstructure of Ceramics

Subtask 5 of Task 12122

B. J. Hockey, N. J. Tighe

The objective is to investigate the relation between structural and

mechanical properties of ceramic materials. Techniques of high-resolution

TEM and SEM are developed and applied to study deformation, fracture and

wear processes in hard materials.

During the past year, work was directed toward: (1) understanding

the microstructure of ceramic capacitors, (2) elucidating mechanisms of

erosion in brittle materials, and (3) clarifying the causes of strength

degradation at elevated temperatures in non-oxide ceramics. Work on ceramic capacitors is discussed above in this report. In this section,

studies of strength degradation mechanisms in non-oxide ceramics will be

reviewed.

The structural stability of ceramics such as Si 3 N 4 and SiC, which

are intended for high-temperature turbine applications, depends on chemical reactions that occur between these materials and oxygen at

elevated temperatures. Although these materials have excellent mechanical

properties at room temperature their properties are often degraded by

these reactions. Usually minor chemical components of the ceramic are

the main cause for substantial losses in strength. In hot-pressea Si 3 N 4
doped with MgO (as a

• when P-cenToftTr^T f°TMati °" results

grade of hot-p££«?Tt £

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9

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124
1

formance at cryogenic temperatures combining both technology and science.

The conference defined pressing research needs such as: (1) development

of improved polymers for 1 ow-temperature use, especially those with

improved toughness and lower notch sensitivity; (2) standardization of

composite and polymer systems leading to reduced cryogenic variability

and forming a basis for systematic materials development; and (3) improving

the understanding of radiation resistance of polymers at 4 K, leading to

the development of improved materials suitable for use in magnetic-fusionenergy reactor systems. A second session of this topical conference was

held in Geneva, Switzerland, during August 1980. A paper emphasizing

the need for increased standardization of composite materials was presented,

reflecting a continued NBS role in this area.

The composite program during the past year saw the publication of a final report to the USAF on the properties and applications of advanced

composites for the construction of prototype lightweight, airborne superconducting-magnet systems. This work included a comprehensive update of

the 1975 reviews addressing the effect of cryogenic temperatures on the

performance of composite laminates. This will also be published separately

in the literature. Also, an extensive tutorial review of composite-materials

technology as applied to the cryogenic range was completed as a chapter in

a forthcoming book entitled "Materials at Low Temperatures."

Research activities during the past year concentrated on the failure

modes of composite laminates, emphasizing the role played by cryogenic

temperatures. One effort undertook to develop the analytical base and

techniques of failure analysis for fabric-reinforced nonmetal lie com- posites tested under compression in the 295 to 4 K temperature range.

The influence of constituent behavior and properties as an additional

and integral part of the failure analysis is primary to an analytical

interpretation of compressive fracture for such materials. There is

presently a dearth of information concerning a systematic analytical

treatment of room and cryogenic temperature behavior in glass-fabric

reinforced composites. These materials to date have been considered too

complex to be represented by analytical models. This study is specifically directed toward the fracture analysis of a G-10CR cryogenic-grade

laminate. The information derived from such studies can provide a base that can be expanded and used for improved testing techniques for

predicting behavioral and property patterns for fabri c-rei nforced nonmetal lies at normal and low temperatures.

A fundamental assessment of the effect of cryogenic temperatures on the initial states of failure in graphite-epoxy materials was begun as part of a postdoctoral research program. This work examines the interrelationship between moisture and temperature on the damage accumulation

in angle-ply laminates subjected to tensile loading. The object is to

determine quantitatively how moisture and temperature affect the residualstress state of individual layers of the laminate and to correlate these

data with damage accumulation at the free laminate edge. An essential

step in this program is the establishment of finite element analytical

models to predict the laminate-edge stress state. The work will make a significant contribution to predicting damage accumulation in composite
materials. The concept of a characteristic damage state for composites

inherent in this approach is essential for the implementation of fracturemechanics principles to composite materials.

NBS has continued cooperative work with the U.S. laminating industry

to refine the common specifications for the CR grade of glass-fabricreinforced laminates. The possibility of adding a random-mat glassreinforced laminate and a uniaxial gl ass-rei nforced laminate to the list

of CR-grade products has been explored. Special emphasis has been

placed on development of standardized grades for service under irradiation at 4 K. As part of a DOE program concerned with irradiation effects

on composite electrical insulators in superconductivity magnets, NBS has

obtained materials irradiated at Oak Ridge National Laboratory and has

begun a study to correlate the molecular-level damage (measured in the

Polymer Science and Standards Division) with property degradation. We

have continued our interaction with the U.S. laminating industry to ensure that future radiation test materials are well controlled and

amenable to fabrication as standard CR grades, should results warrant

this approach.
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 appplicable 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. In these applications, the materials

of construction (steels and aluminum alloys are typical) are highly

plastic (nonlinear) before fracture. Consequently, linear-elastic

methods do not apply and 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 contribute to the scientific basis (i.e.,

elastic-plastic fracture mechanics) for developing fracture-prevention

procedures applicable to materials that exhibit extensive plasticity

before fracture.

The Fracture and Deformation Division program in elastic-plastic

fracture mechanics consists of five subtasks:

1. J-integral and crack-tip-opening-displacement evaluations are used to characterize the fracture resistance of structural

alloys and determine the driving force for fracture under

elastic-plastic conditions.

2. Fitness-for-service criteria are being used to evaluate the

significance of defects, particularly in weldments, on the

basis of plastic-strain cycling fatigue tests, elastic-plastic

fracture-mechanics concepts, and nondestructive evaluation

procedures.

3. The elastic-plastic fracture properties of alloys and weldments used for 1 ow- temperature applications, such as LNG

tankage and superconducting-magnet structures, are being

eval uated.

4. Elastic-deformation phenomena are being studied to contribute

to our understanding of the fundamental basis of strength.

5. Test methods and standards are being developed for the characterization of the fracture behavior of materials.
J-Inteqral and Crack-Tip-Qpeninq-Displacement (CTOD) Evaluations

Subtask 1 of Task 12123

D. T. Read, R. W. Cheng, R. deWit, J. G. Early, H. I. McHenry

The J-integral and the CTOD are simply related characterizations of

the elastic-plastic field in the vicinity of the crack tip. The value

of the J-integral for any contour surrounding the crack tip has been

shown experimentally to be a criterion for the onset of crack extension.

Experimental methods have been developed to determine the critical value

of J, J^, and of CTOD, Si, which are measures of the plane-strain

fracture toughness. The Fracture and Deformation Division is conducting

research using the J-integral and CTOD methods to characterize the

fracture toughness of structural alloys, to measure the driving force

for fracture under elastic-plastic loading conditions, and to conduct

analytical studies to evaluate the influence of geometric configuration

and stress-strain characteristics.

The Division is conducting a program to develop a J-integral design

curve along the lines proposed in the Draft British Standards Rules for

Derivation of Acceptance Levels for Defects in Fusion Welded Joints.

The program involves the experimental determination of the relationships

of the J-integral fracture toughness, the applied strain, and the defect

size. Initial tests involved tensile panels of ship steel with edge

cracks, center cracks, surface cracks, and cracks adjacent to stress

concentrations. The influence of residual stress on the design curve

will be assessed using wide-plate test specimens fabricated by the Navy

and tested in the NBS large-scale test facility. Results to date have

led to the development of an extended elastic-perfectly-plastic model

applicable to through cracks in open areas of tensile panels. Stress

concentration effects can be accounted for by a uniform strain model and

the Neuber strain concentration. Future work will emphasize surface-flaw

modeling and tests on weldments.

Finite-element-analysis studies are being conducted to complement

the experimental program to develop a J-integral design curve. The

analytical work is being performed by Professor Robert Dodds of the

University of Kansas under contract to NBS. Work in progress is directed

toward developing relationships between the J-integral and nominal

strain for cracks adjacent to stress concentrations such as holes and

elliptical cutouts. The objective of the finite element analyses is to

demonstrate that the experimental results can be numerically simulated

and to generalize the experimental results to a variety of stress con- centrations in a manner that is more efficient than actual experiments.

A study of fracture-characterizi ng parameters is being conducted

for NBS by Dr. M. G. Dawes of the Welding Institute, Abington, England.

Dr. Dawes is performing the research at the Boulder laboratories thereby

permitting the improvement of our experimental capabilities, particularly

in the area of CTOD testing. The experimental program addresses the

influence of plastic constraint on observed fracture behavior. EsDeciai!

large errors can be introduced by present experimental measurements of
critical J-integral or CTOD values for the onset of cleavage fracture,

which often show large variations due to differences in crack-tip-region

plastic constraint (CPC) 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 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 for quantifying the magnitude of the crack- tipregion plastic constraint. 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 will 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. The investigation is being conducted

for NBS by Ohio State University under the direction of Dr. Ing-Hour Lin.

Dr. Lin is developing a model that is an extension of the work of Ritchie,

Rice, and Knott. It uses the strain-field solutions of Hutchinson to

predict stress-state effects on the brittle-to-ductile fracture-mode

transition. The data developed by Dawes will be used to evaluate the

resulting theoretical predictions. In addition to plastic constraint

effects, metallurgical factors are being investigated, particularly

grain-size effects, and statistical treatments of the fracture-mode

transition.

Fitness-for-Service

Subtask 2 of Task 12123

Y.-W. Cheng, C. M. Fortunko, E. L. Brown, M. B. Kasen, H. I. McHenry,

J. H. Smith, J. G. Early, R. deWit, G. E. Hicho

A program is being conducted to establish weld-quality requirements

for the Alaska Natural Gas Transportation System (ANGTS). Analytical

studies involve modeling of the significance of defects using methods

comparable to those used for the trans-Alaska pipeline assessment con- ducted previously. Experimental studies involve the measurement of

crack-mount opening-displacement (CMOD) as a function of remote strain

for tensile panels with surface flaws. These specimens are also instrumented with strain and remote displacement gauges to evaluate the J-integral

for two-diemnsional contours (two paths) where the surface flaw is

treated as an edge crack in one case and as a through- thi ckness center

crack in the other case. The results of these experimental and analytical

studies will be used to assess the validity of the critical COD models

used in the trans-Alaska oil pipeline. These models have been reassessed

and their sensitivities to applied stress and material tensile flow

properties compared and evaluated. In the case that the critical COD

model does not represent the experimental observations, work will follow

on the development of an improved analytical model.

1
Testing has been completed to determine the fracture toughness of

girth welds from API-grade X-65 line pipe. Metal lographic analyses were

conducted, and fracture toughness measurements were made using the

multiple-specimen procedure to determine for the welds. Research is

continuing to characterize weld defects, particularly slag porosity, in

girth welds from gas-transmission pipelines. Radiographs were made of

these welds and were analyzed to characterize the length and width of

the defects. These results will be correlated with the results of

metallographic analysis to assess the reliability of methods for characterizing the weld defects. NBS is working closely with the Canadian

gas-pipeline materials research at Alberta Gas Trunkline Company and the

Canadian Welding Institute, the Northwest Pipeline Company, the Welding

Research Council, the American Pipeline Institute standards committee,

and Battel le Memorial Institute in this program.

A major effort has been started to develop ultrasonic inspection

methods for determining the depth of flaws in weldments. Initial objectives relate to the fi tness-for-service standards being developed for

the ANGTS system. An NDE laboratory has been built, equipped, and

staffed during the past year to conduct the NDE investigations. Initial

emphasis has been on the development of electromagnetic acoustic transducers

(EMATS) to size defects. The EMATS excite horizontal shear (SH) waves

in the weldments that are reflected by flaws in proportion to their

depth. A prototype EMAT system has been designed, built, calibrated,

and evaluated for inspecting pipeline girth welds. The results to date

indicate that the EMATS have a sufficient signal-to-noise ratio to

effectively size flaws in pipeline girth welds. The emphasis of future

research will be on developing the physical basis through parametric

studies to permit industry to build a system for field applications.

A new program has been initiated to evaluate the suitability of

high-strength low-alloy (HSLA) steels for transportation applications.

HSLA steels are a new class of materials that use microalloying, inclusion shape control, and controlled processing to significantly improve

the strength, toughness, and weldability of conventional steels. Their

application in transportation systems is currently limited by the lack

of improved fatigue strength when welded. Despite improved strength and

toughness, the durability of HSLA steel weldments is essentially the same as conventional steels. The reasons for the relatively poor performance in fatigue are not clearly understood. Stress concentration effects,

residual stress, and metallurgical deterioration have been suggested as possible causes. The relative importance of these contributing factors

is being evaluated to improve fatigue strength. The experimental approach

is to metal 1 urgical ly examine fatigue-tested samples of HSLA steels with

and without welding, stress concentrations, and residual stress. Ford

Motor Company, General Motors Corporation, and the HSLA steel suppliers

are collaborating with NBS on this program.

A conference entitled "Fi tness-for-Service of Welded Structures"

was cosponsored by NBS and the American Welding Society (AWS). It was

held in Indianapolis, Indiana, in May 1980. Over 150 engineers and

researchers attended and rated the conference as highly informative and

120
beneficial. The conference featured twelve invited speakers covering

the role of design, analysis, materials, selection, fabrication controls,

and quality assurance in the implementation of fitness-for-service

standards. Experience with fi tness-for-service standards for steel

weldments, nuclear pressure vessels, and pipelines was reviewed by

leading authorities in these fields.

Low-Temperature Properties

Subtask 3 of Task 12123

R. P. Reed, R. L. Tobler, H. I. McHenry, J. M. Arvidson, R. E. Schramm

A major developing technology is the use of superconducting magnets

in energy applications. High magnetic fields are required for fusionplasma 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. Power

transmission via superconducting underground cables is under intensive

development. 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 liquidhelium temperature (4 K) up to 20 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 our Division. These programs have produced a low-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, Colorado; and joint research programs

between NBS and its subcontractors , which have included Battel le, Westinghouse, General Electric, Martin-Marietta, Tel edyne-McKay , Alcoa, Armco,

and Belfour-Stulen. Major research emphasis has been to characterize

the austenitic stainless steels (AISI 304, 316, and 310 grades) and to

develop reliable welding processes and filler metals for welding austenitic

stainless steels for use at low temperatures. The development and

characterization of low temperature composite insulator standards is

discussed in the previous task.

Superconducting magnets are needed for both fusion and MHD applications to contain and direct the flow of the plasma. A major obstacle to

the development of large superconducting magnets, to operate at -269 °C,

is the requirement' of strong, tough, and weldable alloys to restrain the

large magnetic forces. We are developing and characteri zi ng a new class

of austenitic stainless steels for this application. 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 with the addition of 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 -269 °C. Results indicate that the dependence of flow
strength on nitrogen concentration increases dramatically at low temperatures. Nitrogen additions suppress both the body-centered-cubic and

close-packed-hexagonal martensitic transformations. A linear relationship

between fracture toughness (from J-integral measurements) and tensile

yield strength at -269 °C was found. The temperature dependence of the

flow strength is critically dependent on austenite stability; low austenite

stability results in strain-induced martensite formation, which produces

low flow strengths. An analytic expression has been developed relating

flow strength to temperature in the absence of martensitic transformation

for austenitic Fe-Cr-Ni alloys. Alloys containing controlled nitrogen

and manganese concentration have been supplied by U.S. Steel and Armco

Steel Corporations.

Fracture-mechanics evaluation of weldments continued. The fracture

toughness of 316L welds at 4 K decreased in the following order: gas-t

ungsten-arc, gas-metal -arc, and submerged-arc. An evaluation of 5083-aluminumalloy weldments for liquid-helium service indicated remarkable consistency

in toughness for welds provided by six industrial firms using the gas-metal -arc

process.

The US/USSR scientific exchange program on Cryogenic Materials and

Welds is being maintained by the National Science Foundation. A 20C i— 1 6N i

6Mn-.2N stainless steel alloy weldment supplied by the Paton Institute

was evaluated for use in superconducting magnets. The combination of

strength and toughness in the submerged-arc welds of this alloy at 4 K is superior to any alloy previously evaluated and is comparable to

expected values for the matching base plate. Thus, this alloy appears

promising for 1 i quid- he! i urn service.

Elastic Deformation Phenomena

Subtask 4 of Task 12123

H. M. Ledbetter

Elastic constants provide fundamental information about solids to

both the solid-state physicist, who wonders what holds solids together,

and to the materials engineer, who wonders what tears them apart.

Our effort on solid-state elastic constants comprises three categories: (1) critical reviews of el asti c-property data, (2) experiment,

and (3) theory. Related theoretical studies on solid-solid phase transitions are also in progress.

Our critical reviews focus on materials of both scientific and

technological importance: iron, nickel, copper, zinc, iron-nickel

alloys (completed); copper-zinc alloys, aluminum (in progress) magnesium,

titanium, and others (planned). Besides recommending "best" elastic

constants, these reviews consider effects of variables such as temperature, pressure, alloying, magnetic field, and mechanical deformation,

and identify suggested areas for further study. From both university

and industrial 1 aboratories , we have received considerable encouragement

for more studies of these kinds.

122
Our experimental studies deal with metals, alloys, composites, and

polymers; with single crystals and with polycrystals. Notable recent

studies include: (1) the effects of interstitial carbon and nitrogen on the elastic constants of austenitic stainless steel 304, (2) elastic

constants of a wide range of commercial austenitic stainless steels,

(3) accurate measurements (for the first time) of polycrystalline copper's

low-temperature elastic constants, (4) determination of Young's modulus

and internal friction at low temperatures for glass-epoxy composites and

for the epoxy resins, and (5) orientation dependence of Young's modulus

and damping in glass-cloth-epoxy composites. We are developing two new

(for NBS) experimental capabilities: a forced-vibration system for

low-frequencies (1-100 Hz) and a continuous-wave, standing-wave method

for high-frequencies (1-10 MHz). The first system is being used to

study polymers and composites (high damping materials). The second

system is being used initially to investigate cracks in ceramic capacitors

used in inertial -guidance systems.

Our theoretical efforts focus on three principal problems: (1) relationships between elastic constants and other physical properties,

particularly the Debye characteristic temperature; (2) relationships

between physical properties of single crystals and polycrystals, that

is, the tensor-averaging problem; and (3) elastic constants and interatomic potentials. On the latter problem, col laborating with T. Suzuki

(Tsukuha University), we recently calculated the elastic constants of ' the alkali metals using pseudopotentials and related these constants to

the phase-transition behavior of the metals. From these calculations is

emerging an exciting new concept for low-temperature solid-state nucleation of the new phase. Basically, the traditional surface-energy-term

approach, which fails to predict reaction rates, is replaced by a latticedeformation-energy term that might. These calculations also provide new insights into the relative phase stability of sodium, which exhibits

three crystal structures. On the single-crystal: polycrystal elasticconstants problem, much of our work is now done in collaboration with

the theoretical group of Prof. E. Kroner at the University of Stuttgart.

These studies are summarized in a foreign trip report by H. Ledbetter

(August 1980). In terms of elastic-constant; physical -property relations,

we would like to extend our preliminary studies on bcc transition metals

where the superconducting transition temperature, T , relates to the

Cauchy discrepancy, C 12 -C 44 . Collaborating with Prof. S. K. Datta

(University of Colorado), we have carried out perhaps the most thorough

comparison to date between theory and observation for the elastic constants

of a uniaxial ly reinforced metal -matrix composite.

Test Methods and Standards

Subtask 5 of Task 12133

B. W. Christ, R. deWit, J. G. Early, G. E. Hicho, C. G. Interrante,

J. H. Smith, W. A. Willard

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

fol lows:

Development of Standard Reference Materials (SRM) : Under sponsorship of

the NBS Office of Standard Reference Materials, a series of SRM's has

been developed for calibrating instruments used to determine the level

of retained austenite in ferrous alloys. Samples to be sold as the SRM

are prepared from metal powders of austenite and ferrite phase materials

and consolidated by powder metallurgical techniques. These samples are

then calibrated by x-ray and metal lographic analysis and certified for

sale. During the past year, a series of austenite SRM samples containing

15 percent austenite and a series of specimens containing five percent

austenite have been prepared, calibrated, and will be offered for sale

by the Office of Standard Reference Materials. To complete this series,

SRM's containing 2.5 percent and 30 percent austenite will be prepared

during the coming year. The availability of these standard reference

materials is essential for the accurate calibration of instruments to measure the retained austenite in materials purchased by specifications

which place a maximum on retained austenite.

Standard Test Methods for Hydrogen Embrittlement Cracking : Hydrogen

embrittlement cracking (HEC) is a significant cause of unexpected fracture

in structures made from ferrous alloys. Reliable test methods to assess

the susceptibility of ferrous alloys are required to reduce the incidence

of HEC in ferrous alloys. An original test method to assess the thermal

diffusivity of hydrogen in metals has been developed by J. G. Early.

This test method is required to assess the tendency for hydrogen to be

absorbed and cause embrittlement in ferrous metals. This test method

has been calibrated with palladium and will be used to determine the

thermal diffusivity of hydrogen in several ferrous alloys.

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.

This project will be carried out cooperatively with the NBS Reactor

Radiation Division. Results of this highly innovative approach will

lead to a much clearer understanding of the mechanism for the interaction

of stress and hydrogen in causing embrittlement of steel.

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 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 in foreign countries and to 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 requirements on materials for use

in seamless steel vessels.

124
An extensive program was initiated this year to develop reliable

test methods and acceptance standards for the use of composite pressure

vessels for the transportation of hazardous materials. At present,

attention is focused on cylinders made by overwrapping aluminum cylinders

with fiberglass reinforced plastic and Kevlav. Tests are being assessed

and developed for assessing the safety of these vessels in ambient

environments, high temperature environments, and in acqueous environments. The results of these tests will be used by QHMR to develop

specifications for allowing wide scale use of composite cylinders.

Development of Test Method for Elevated Temperature Stress--Corrosion

Work has been completed, under Department of Energy sponsorship, on the

development of a test method for assessing the susceptibility of materials

to stress-corrosion cracking at elevated temperature. This test method

permits the use of a thermally compensated, pre-cracked test specimen

for determining crack growth rate i_n situ in field tests in aggressive

envi ronments.

Analysis of Shipbuilding Materials Standards : Under sponsorship of the

Coast Guard, a program was initiated this year with the principal effort

in the analysis of American, German, and Japanese materials standards

and their equivalency or lack of equivalency. Considerable progress has

been made on the initial group of 60 specifications. The results of

this study will be submitted for a Symposium on Shipbuilding Standards

to be held in 1981 sponsored by ASTM and the Society of Naval Architects

and Marine Engineers.

Development of Standards for Resource Recovery : In cooperation with the

ASTM Committee E-38 on Resource Recovery standards E702, "Standard

Specification for Municipal Ferrous Scrap," and E701 , "Standard Methods

of Tests for Municipal Ferrous Scrap," were developed and approved.

J. G. Early of the Fracture and Deformation Division served as Secretary

of the E-38 Committee and as a principal author of these standards.

These standards are essential to permit the economical recycling of

ferrous materials in municipal waste. A chapter entitled "Recycling

Ferrous Scrap" is in preparation and will be published in the 3rd Edition

of the "Encyclopedia of Chemical Technology" early in 1981.

ASTM Subcommittee E24.03 - Alternative Fracture Test Methods : ChairmanshiD

of this subcommittee involves fostering fracture test methods that use simple tests of notched or precracked specimens not based upon fracture

mechanics analysis. These alternative test methods are frequently used

in fracture control, especially for metals with high toughness. They

include the Precracked Charpy and the Dynamic Test Test Methods. For

the precracked Charpy test, separate methods are being developed for

impact testing and for slow-bend testing. The forerunner to these

developments is an extensive analysis conducted at NBS on "The Significance

of Precracking Variables for Slow-Bend Charpy Tests." Future activities

will include participation in round-robin activities on these test

methods.

135
Termi no logy : Our work in the area of terminology is concerned mainly

with terminology for fracture testing and 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 Committee on Definitions of Metallurgical Terms.

The Chairman and Secretary of SC E-24.05 serve in a diversified set

of roles to facilitate and coordinate the development of terminology

within the many task groups of eight subcommittees of Committee

E-24. This terminology includes development definitions, descriptions

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.

ASTM Task Group E-24. 06. 02 - Application of Fracture Analysis Methods : Membership in this task group involves participation in a predictive

round-robin whose objective is to experimentally verify whether or not

analytical methods currently in use can predict failure of complex

structural components containing cracks from results of laboratory

tests. The results of a great deal of analytical work done over the

past year are now being coordinated by the Task Group.

ASTM Task Group E-1Q.Q2-C on Interpretation of C harpy Data : Membership in this task group involves participation in the development of a standard for Computer Analysis of Charpy Impact Test Data, and it has

included the writing of an NBS Appendix for this proposed standard. The

appendix is titled, "General Method for Computer Analysis of Charpy

Impact Data.

I

iJO
Other Activities of the

Fracture and Deformation Division

Invited Talks

Energy Variations in Diffusive Cavity Growth

Fall Meeting of Basic Science and Nuclear Divisions, American

Ceramic Society, New Orleans, Louisiana

T.-J. Chuang

October 1979

Energy Related Standards in Resource Recovery

USA Energy Self-Sufficiency Symposium, New Orleans, Louisiana

J. G. Early

January 1980

Deformation and Fracture Mechanism Maps with an Introduction to

Crack Growth Mechanism Maps

Pennsylvania State University, Materials Science and Engineering

Seminar

R. J. Fields

February 1980

Aspects of Subcritical Crack Growth in Organic Fluids

Glass Division, American Ceramic Society

Bedford Springs, Pennsylvania

S. W. Freiman

October 1979

Stress Corrosion of Ceramics

Case Western Reserve University, Cleveland, Ohio

S. W. Freiman

January 1980

Fractographic Analysis of Brittle Fracture

NASA Lewis Research Center, Cleveland, Ohio

S. W. Freiman

January 1980

Understanding and Prediction of Delayed Failure in Ceramics

Annual Meeting, Canadian Ceramic Society, Ottawa, Canada

S. W. Freiman

February 1980

Effect of Stress on Raman Spectra of Optical Fibers

Annual Meeting, American Ceramic Society, Chicago, Illinois

S. W. Freiman

April 1980

N8S Program

NBS-0QE Workshop on Materials at Low Temperatures , Vail, Coloraco

R. P. Reed

October 1979
US/USSR Exchange Program

NBS-OOE Workshop on Materials at Low Temperatures , Vail, Colorado

R. P. Reed

October 1979

Fracture Energy of Si 3 N4 Annual Meeting, American Ceramic Society, Chicago, Illinois

R. R. Rice

April 1980

Effect of Alkali Ion Exchange on Crack Propagation in Glass

Glass Division, American Ceramic Society

Bedford Springs, Pennsylvania

C. J. Simmons

October 1979

Relation of Subcritical Crack Growth to Chemical Durability of

Glasses in Aqueous Solutions

Annual Meeting, American Ceramic Society, Chicago, Illinois

C. J. Simmons

April 1980

Requirements for Failure Analysis Methodology

ASME Pressure Vessels and Piping Division Meeting, Foster-Wheeler

Corporation, Livingston, New Jersey

J. H. Smith

December 1979

Fracture Mechanics Analysis to Determine Allowable Flaw Sizes in

Girth Welds

DoT-NBS Pipeline Meeting, Boulder, Colorado

J. H. Smith

March 1980

Safety Factors in Fatigue Design: Arbitrary and Rational

ASME Symposium-Critical Materials and Lubrication Issues for Pressure

Vessels, Piping, Pumps, and Valves, San Francisco, California

J. H. Smith

August 1980

Conditions for Lattice Trapping of Cracks: Normal and Anomalous

Glass

American Ceramic Society, 82nd Annual Meeting, Chicago, Illinois

R. M. Thomson

April 1980

Effect of Oxidation on the Flaw Population in Si 3 N 4 Compacts

American Ceramic Society, New Orleans, Louisiana

N. J. Tighe

October 1979

123
Corrosion and Stress Corrosion of Ceramics

Sandia Laboratories, Albuquerque, New Mexico

S. W. Freiman

May 1980

Determining Crack Growth Behavior from Delayed Failure Test

American Ceramic Society, 82nd Annual Meeting, Chicago, Illinois

E. R. Fuller, Jr.

April 1980

High-Temperature Double-Torsion Studies of Refractory Concretes

ASTM Symposium on Fracture Mechanics Methods for Ceramics, Rocks,

and Concrete, Chicago, Illinois

E. R. Fuller, Jr.

June 1980

Fractographic Evaluation of Slow Bend Precracked Charpy Specimens

ASTM E24 Committee Meeting, Pittsburgh, Pennsylvania

G. E. Hicho

October 1979

Erosion of Ceramics by Solid Particle Impact

Army Research Office Workshop on "Mechanisms of Erosion in Hot

Flowing Media," Fort Myers, Florida

B. J. Hockey

October 1979

Role of the Committee on Terminology in ASTM

Meeting of Subcommittee E9.06 on Statistical Aspects of Fatigue,

Pittsburgh, Pennsylvania

C. G. Interrante

October 1979

A Review of COT Recommendations for ASTM Terminology

Meeting of Subcommittee E9108 on Fatigue under Cyclic Strain and

Executive Subcommittee E9.90 on Fatigue, Pittsburgh, Pennsylvania

C. G. Interrante

October 1979

Terminology in ASTM

Meeting of ASTM Editorial Subcommittee B5.91 on Copper and Copper

Alloys, Galt House, Louisville, Kentucky

C. G. Interrante

March 1980

Terminology in ASTM

Meeting of ASTM Subcommittee B9.01 on Nomenclature for Metal Powder

and Metal Powder Products, Galt House, Louisville, Kentucky

C. G. Interrante

March 1980
Terminology in ASTM

Meeting of ASTM Subcommittee C8.06 on Nomenclature for Refractories, Galt House, Louisville, Kentucky

C. G. Interrante

March 1980

fracture of Steel Plate Materials under Abusive Service Conditions

Mechanical Failures Prevention Group Symposium in Ground Transportation Systems, 31st Meeting, NBS, Gaithersburg, Maryland

C. G. Interrante

April 1980

Standardizing Nonmetallic Composite Materials for Cryogenic Applications

ICMC Conference on Nonmetallic Materials at Low Temperatures-II

Geneva, Switzerland

M. B. Kasen

August 1980

High Temperature, High Pressure, Fluid Handling Facility

Task Group on Geothermal Wells, Committee on Oil-Well Cements,

American Petroleum Institute, Tulsa, Oklahoma

R. F. Krause, Jr.

December 1979

Strength Measurements of Cements Following Hydrothermal Exposures

Task Group on Geothermal Wells, Committee on Oil-Well Cements,

American Petroleum Institute, San Antonio, Texas

R. F. Krause, Jr.

March 1980

Strength Measurements of Cements Following Simulated Geothermal

Exposures

Task Group on Geothermal Wells, Committee on Oil-Well Cements,

American Petroleum Institute Standardization Conference, Houston,

Texas

R. F. Krause, Jr.

June 1980

Structural Alloys for Superconducting Magnet Systems

Westinghouse Research Laboratori es , Pittsburgh, Pennsylvania

H. I. McHenry

June 1980

Fractographic Analysis of Delayed Failure in Ceramics

ASTM Symposium on "Fra-ctography and Materials Science," Williamsburg,

Vi rgi ni

J. J. Mecholsky

November 1979

1*0
Direct Measurement of the J-Contour Integral

International Conference on Analytical and Experimental Fracture

Mechanics, Rome, Italy

D. T. Read

June 1980

Deformation of CR-Spinel Refractory Brick

American Ceramic Society, Chicago, Illinois

N. J. Tighe

April 1980

Cryogenic Properties of Stainless Steel Welds

NBS-DOE Workshop on Materials at Low Temperatures, Vail, Colorado

T. A. Whipple

October 1979

Cryogenic Properties of Stainless Steel Welds

AWS Meeting, Los Angeles, California

T. A. Whipple

April 1980

Proof Testing of Ceramics: Effect of Multiregion Crack Growth

American Ceramic Society, 32nd Pacific Coast Region Meeting, Seattle,

Washi ngton

S. M. Wiederhorn

October 1979

Micromechanisms of Crack Growth in Ceramics and Glasses in Corrosive

Envi ronments

Micromechanisms of Crack Growth Conference, Cambridge, England

S. M. Wiederhorn

March-April 1980

Effect of Region II Crack Growth on Proof Testing

American Ceramic Society, 82nd Annual Meeting, Chicago, Illinois

S. M. Wiederhorn

April 1980

Erosion of Ceramic Materials

Argonne National Laboratori es , Chicago, Illinois

S. M. Wiederhorn

May 1980
Technical and Professional Committee Participation and Leadership

American Association for the Advancement of Science

S. W. Freiman, B. J. Hockey, and J. H. Smith, Members

American Ceramic Society

T. Chuang, R. J. Fields, S. W. Freiman, E. R. Fuller, Jr.

(Chairman Elect of the Baltimore-Washington Chapter), B. J. Hockey, 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 Chemical Society

R. F. Krause, Jr. and C. L. McDaniel, Members

American Institute of Mining, Metallurgical, and Petroleum Engineers

(AIME)

Metallurgical Society

B. W. Christ, R. deWit (Past Key Reader), J. G. Early, R. S. Polvani, and J. H. Smith, Members

Composites Committee

M. B. Kasen, Member

Definitions of Metallurgical Terms

C. G. Interrante, Member

Long-Range Planning Committee

C. G. Interrante, Chairman

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 National Standards Institute (ANSI)

Materials and Stresses Committee of the Pressure Piping Code, B31

H. I. McHenry, Member

American Petroleum Institute

Task Group on Cements for Geothermal Wells

E. R. Fuller, Jr., and R. F. Krause, Jr, Members

142
American Physical Society

R. C. Dobbyn, E. R. Fuller, Jr., R. deWit, and B. J. Hockey,

Members

American Society for Metals (ASM)

B. W. Christ, T. Chuang, R. deWit, J. G. Early, R. J. Fields,

G. E. Hicho, C. G. Interrante (Past Chairman, Washington

Chapter), H. I. McHenry, R. S. Polvani, T. R. Shives, J. H. Smith, and N. J. Tighe, Members

American Society for Testing and Materials (ASTM)

R. deWit, R. C. Dobbyn, B. W. Christ, J. G. Early, R. J. Fields, S. W. Freiman, E. R. Fuller, Jr., G. E. Hicho, C. G.

Interrante, M. B. Kasen, T. R. Shives, J. H. Smith, R. L. Tobler, and S. M. Wiederhorn, Members

Committee on Terminology (COT) of Committee on Standards

C. G. Interrante, Member

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

Subcommittee 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

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. deWit, R. J. Fields, E. R. Fuller, Jr., G. E. Hicho, C. G. Interrante

(Member of Executive Committee), 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. deWit, Secretary

Task GrouD E24.06.02 Predictive Round Robin on Fracture

R. deWit, Member
Subcommittee E24.07 on Fracture of Non-Metals

S. W. Freiman, Chairman and E. R. Fuller, Jr., Member

Subcommittee E24.07.01 Fracture Toughness Testing of Concretes

and Rocks

E. R. Fuller. Jr., Member

Subcommittee E24.07.02 Double-Torsion Technique

E. R. Fuller, Jr., Member Task Group E28.04.03 Verification of

Alignment Under Tensile Load

B. W. Christ, Chairman

Subcommittee E38 Resource Recovery

J. G. Early, Secretary and Member of Executive Committee

Subcommittee E38.02 Ferrous Metals Resource Recovery

J. G. Early, Secretary

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 (ASME)

T. Chuang, R. deWit, R. C. Dobbyn, J. H. Smith, and N. J. Tighe, Members

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. deWit, Member

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

American Welding Society

C. G. Interrante, H. I. McHenry and J. H. Smith, Members

Conference Program Advisory Board, Evaluation of Welded Structures Based on Fitness for Service

H. I. McHenry, Chairman

Technical Activities Committee

H. I. McHenry, Member-at-Large

Compressed Gas Association

Cylinder Specification Subcommittee

B. W. Christ, Member

Department of Energy

Subcommittee on Erosion/Corrosion of Turbine Materials

B. J. Hockey, Member

14.
Department of Transportation

Technical Pipeline Safety Standards Committee

B. W. Christ and J. H. Smith, appointment by Secretary of

Transportation

Electron Microscopy Society of America

N. J. Tighe, Member

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 Institute of Welding

Commission XV - Fundamentals of Design and Fabrication for

Welding

J. H. Smith, Member

International Powder Metallurgy Society (Planseeberichte fur

Pulvermetall urgie, Austria)

J. G. Early, Member

International Society for Stereology

R. deWit, Member

International Standards Organization (ISO)

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

Maryland Institute of Metals

R. deWit, Member

Mechanical Failures Prevention Group

T. R. Shives and W. A. Willard, Editors

Metals Properties Council (MPC)

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

National Academy of Sciences (NAS)

Project Advisory Committee on Investigation of Steels for Improved Weldability in Ship Construction

H. I. McHenry, Chairman

-i i ~ 1-rO
Ship Materials, Fabrication and Inspection Advisory Group of

the Ship Research Committee

H. I. McHenry, Member

National Institute of Ceramic Engineers

R. J. Fields, Member

National Materials Advisory Board (NMAB)

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

New York Academy of Sciences

R. deWit, 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

Sigma Xi

T. Chuang, J. G. Early, B. J. Hockey, R. S. Polvani and J. H. Smith, Members

Society for Natural Philosophy

R. deWit, Member

Standards Committee for Women

N. J. Tighe, Member

U.S. Civil Service Examiners for Metallurgist

Interagency Board

J. G. Early, Chairman

Washington Academy of Sciences

R. deWit, Member and C. G. Interrante, Delegate on the Board of

Managers

Washington Academy of Sciences Board of Managers

E. R. Fuller, Jr., Representative for Bal timore-Washi ngton Chapter

of American Ceramic Society

Washington Society for Electron Microscopy

B. J. Hockey and N. J. Tighe, Members
Welding Research Council (WRC)

Long-Range Planning Committee

H. I. McHenry, Member

Pressure Vessel Research Committee (PVRC)

C. G. Interrante and J. H. Smith, Members

PVRC Hydrogen Embrittlement Subcommittee

C. G. Interrante, Member

Subcommittee on Line Pipe Steels

M. B. Kasen and H. I. McHenry, Members

Task Group on Field Welding

M. B. Kasen and H. I. McHenry, Members

Weldability (Metallurgical) Committee

H. I. McHenry, Member

J

!

I

!

a

147
Pub! icati ons

Nonmetallic Laminates

B. A. Beck

LNG Materials and Fluids Handbook

N. A. Olien, editor

NBS, Boulder (1980).

Effects of Defects in Nickel -Based Superalloys

Y.-W. Cheng

Semi-Annual Report to Air Force Materials Laboratory, AFML Contract

No. F3361 5-79-C-5074 (March 1980).

Fracture Analysis of a Pneumatically-Burst Seamless-Steel Compression

Gas Container

B. W. Christ, J. H. Smith, and G. E. Hicho

Fracture Mechanics, ASTM STP 677 (1979), p. 734.

Development of Some Analytical Fracture Mechanics Models for Surface Defects in Plates of Ductile Metals

R. deWit and J. H. Smith

Proceedings of the Symposium on Continuum Models of Discrete Systems,

West Germany

Freudenstadt (1979), pp. 264-276.

Development of Some Analytical Fracture Mechanics Models for Pipe1 i ne Gi rth Wei di ng

R. deWit and J. H. Smith

Fracture Mechanics, ASTM STP 700 (1980), p. 124.

An Evaluation of the Performance of Materials and Composites at the

CONOCO Lignite Gasification Pilot Plant—C0 2 Acceptor Process

R. C. Dobbyn, H. M. Ondik, R. C. Dobbyn, W. A. Willard, W. S. Brower,

I. J. Feinberg, T. A. Hahn, G. E. Hicho, M. E. Read, C. R. Robbins,

J. H. Smith, and S. M. Wiederhorn

Report to DOE, Division of Fossil Fuel Processing (1979).

Determination of Combustibles Content of Municipal Ferrous Scrap

J. Duckett, Z. Kahn, and J. G. Early

Resource Recovery Conservation, 4, 301 (1979).

Discussion “A Mechanism of Intergranul ar Fracture During High

Temperature Fatigue"

J. G. Early

Symposium on Fatigue Mechanisms ASTM STP 675 (1979).

Training of Epoxy- Impregnated Superconductor Windings

J. W. Ekin, R. E. Schramm, and M. J. Superczynski

Advances in Cryogenic Engineering, Vol. 26

Proceedings of the 3rd ICMC, Madison, Wisconsin, August 21-24,

1979

A. F. Clark and R. P. Reed, editors

Plenum Press, New York (1980), pp. 677-684.
Mechanical Testing--! 980'

R. J. Fields and J. H. Smith

Metals Progress (1980), pp. 39-45.

Fracture Mechanisms in Pure Iron, Two Austenitic Steels and One

Ferritic Steel

R. J. Fields, T. Weerasooriya, and M. F. Ashby

Metal 1. Trans. VIA, 333 (1980).

Observation of Wedge Cavities in the SEM

R. J. Fields and M. F. Ashby

Scr. Metal 1 . 14 (7), 791-795 (1980).

Safety Factors in Fatigue Design: Arbitrary and Rational

J. T. Fong and J. H. Smith

Critical Materials and Fabrication Issues for Pressure Vessels,

Piping Pumps and Valves

J. T. Fong, R. C. Dobbyn, and L. Mordfin, editors

ASME, New York

NBS Special Publication 588 (1980), p. 89.

Theory of Chemically Assisted Fracture: II. Atomic Models of

Crack Growth

E. R. Fuller, Jr., and R. M. Thomson

J. Mater. Sci. 15, 1027-1035 (1980).

Plastic Deformation of Fine-Grain Alumina (A1 2 0 3 ): II. Basal SI

and Nonaccommodated Grain Boundary Sliding

A. H. Heuer, N. J. Tighe, and R. M. Cannon

J. Am. Ceram. Soc. 63, 53-58 (1980).

Proceedings of Symposium on the Science of Ceramic Machining and

Surface Finishing, II

B. J. Hockey, coeditor

NBS Special Publication 562 (1979).

Erosion of Ceramic Materials: The Role of Plastic Flow

B. J. Hockey and S. M. Wiederhorn

Proceedings of the Fifth International Conference on Erosion by

Liquid and Solid Impact, Cambridge, England, September 3-6, 1979

Cavendish Laboratory, Cambridge, England (1979), pp. 26.1-26.10.

Standard Terminology Relating to Fracture Testing

ANSI/ASTM E616-78: Definitions developed under the jurisdiction of

ASTM Committee E-24 on Fracture Testing, as the direct responsibility of Subcommittee E24.05 on Terminology

C. G. Interrante

Annual Book of ASTM Standards, Part 10

ASTM, Philadelphia (1979), pp. 672-577.

An SRM Containing 15 Percent Austenite

C. G. Interrante and G. E. Hicho

NBS-SRM No. 488

September 1980.
Computer Assisted Impact Testing

C. G. Interrante and S. R. Low

Computer Automation of Materials Testing

ASTM STP 710 (1980), pp. 188-200.

Mechanical, Electrical, and Thermal Characterization of G-10CR and

G-11CR Glass-Cloth/Epoxy Laminates between Room Temperature and 4 K

M. B. Kasen, G. R. MacDonald, D. H. Beekman and R. E. Schramm

Advances in Cryogenic Engineering, Vol. 26

Proceedings of the 3rd ICMC, Madison, Wisconsin, August 21-24,

1979

A. F. Clark and R. P. Reed, editors

Plenum Press, New York (1980), pp. 235-244.

Fracture Strength of p Si a! on

K. Kobayashi , S. Umebayashi , and N. J. Tighe

Ceramic Society of Japan, Yokohama, Japan (1980), pp. 50-51.

Rate of Heat Release Measurements Using Oxygen Consumption

R. J. Krause, Jr., and E. R. Fuller, Jr.

J. Fire Flam. j_2 (1980), pp. 117-130.

Atomically Sharp Cracks in Brittle Solids: An Electron Microscopy

Study

B. R. Lawn, B. J. Hockey, and S. M. Wiederhorn

J. Mater. Sci. 15, 1207-1223 (1980).

Thermal Effects in Sharp Particle Contact

B. R. Lawn, B. J. Hockey, and S. M. Wiederhorn

J. Am. Ceram. Soc. 63, 356-358 (1980).

Orthotropic Elastic Constants of a Boron-Aluminum Composite

H. M. Ledbetter

J. Appl . Phys. 50, 8247 (1979).

Elastic-Constant Variability in Stainless-Steel 304

H. M. Ledbetter, N. V. Frederick, and M. W. Austin

J. Appl. Phys. 51_, 305 (1980).

Anomalous Low-Temperature Elastic-Constant Behavior in Fe-13Cr-19Mn

H. M. Ledbetter

Metal 1. Trans. 1_1A, 543 (1980).

Room-Temperature Elastic Constants and Low-Temperature Sound Velocities

for Six Nitrogen-Alloyed Austenitic Stainless Steels

H. M. Ledbetter

Metal 1 . Trans. VIA, 1067 (1980).

Correlation between Superconducting-Transition Temperature and the

Cauchy Discrepancy in Body-Centered-Cubic Transition Metals

H. M. Ledbetter

Phys. Lett. 77A, 359 (1980).

150
Dynamic Elastic Modulus and Internal Friction in G- 1 OCR and G-11CR

Fibergl as s-Cloth- Epoxy Composites

H. M. Ledbetter

Cryogenics 20 (1980), in press.

Temperature Dependence of Young's Modulus and Internal Friction of

G- 1 OCR and 6-11 CR Epoxy Resins

H. M. Ledbetter and G. Maerz

Cryogenics 20 (1980), in press.

Sound Velocities and Elastic-Constant Averaging for Polycrystall ine

Copper

H. M. Ledbetter

J. Phys. D: Appl. Phys. 1_3 (1980), in press.

Sound Velocities and Elastic Constants of Austenitic Stainless

Steels 304, 310, and 316

H. M. Ledbetter

Metal Sci. (1980), in press.

Stainless-Steel Elastic Constants at Low Temperatures

H. M. Ledbetter

J. Appl. Phys. 5]_ (1980), in press.

A Nitrogen-Strengthened Austenitic Stainless Steel for Cryogenic

Magnet Structures

F. N. Mazandarany, D. M. Parker, R. F. Koenig, and D. T. Read

Advances in Cryogenic Engineering, Vol. 26

Proceedings of the 3rd ICMC, Madison, Wisconsin, August 21-24,

1979

A. F. Clark and R. P. Reed, editors

Plenum Press, New York (1980), pp. 158-170.

Structural Alloys for Superconducting Magnets in Fusion Energy

Systems

H. I. McHenry and R. P. Reed

Nuc. Eng. Des. , Vol. 56, 219-236 (1980).

Fracture Surface Analysis of Optical Fibers

J. J. Mecholsky, S. W. Freiman, and S. M. Morey

Advances in Research and Development

B. Bendow and S. Mitra, editors

Plenum Press, New York (1979), pp. 187-208.

Metallurgical Factors Affecting the Toughness of 31 6L SMA Weldments

at Cryogenic Temperatures

D. T. Read, H. I. McHenry, P. A. Steinmeyer, and R. D. Thomas, Jr.

Weld. J. 59(4), 104-113 (1980).

8Mi»nmn«iif«n<ww*tiwgiln,mLfiiwnmi
Heating Effects during Tensile Tests of AISI 304L Stainless Steel

at 4 K

D. T. Read and R. P. Reed

Advances in Cryogenic Engineering, Vol. 26

Proceedings of the 3rd ICMC, Madison, Wisconsin, August 21-24, 1979

A. F. Clark and R. P.

# Reed, editors

Plenum Press, New York (1980), pp. 91-101.

The Dependence of Strength Controlling Fracture Energy on the Flaw

Size to Grain Size Ratio

R. W. Rice, S. W. Freiman, and J. J. Mecholsky

J. Am. Ceram. Soc. 63(1-2), 129-136 (1980).

Erosion by Solid Particle Impact

A. W. Ruff and S. M. Wiederhorn

Treatise on Materials Science and Technology, Vol. 16, Erosion

C. M. Preece, Editor

Academic Press, New York (1979).

Detection, Diagnosis, and Prognosis

T. R. Shives and W. A. Willard, editors

NBS Special Publication 547 (1979).

Advanced Composites: Design and Applications

T. R. Shives and W. A. Willard, editors

NBS Special Publication 563 (1979).

Metal Corrosion

J. H. Smith

Proceedings of the 4th Annual Conference on Materials for Coal

Conversion and Utilization, Gaithersburg, Maryland, DOE-Conf . -78-

1014 (October 1979).

Quantitative Stereological Methods for Analyzing Important Microstructural Features in Fatigue of Metals and Alloys

J. H. Smith

Fatigue Mechanisms, ASTM STP 675 (1979), p. 671.

Opportunity for Advanced Data Collection Systems for Nuclear Power

Plants--A Discussion

J. H. Smith

In-Service Data Reporting and Analysis, Vol. II, ASME, New York

(1979), p. 148.

Tensile and Fracture Behavior of a Nitrogen-Strengthened, ChromiumNickel-Manganese Stainless Steel at Cryogenic Temperatures

R. L. Tobler and R. P. Reed

ASTM STP 668 (1979).

152
Temperature Dependence of Yielding in Austenitic Stainless Steels

R. L. Tobler, R. P. Reed, and D. S. Burkhalter

Advances in Cryogenic Engineering, Vol. 26

Proceedings of the 3rd I CMC, Madison, Wisconsin, August 21-24, 1979

A. F. Clark and R. P. Reed, editors

Plenum Press, New York (1980), pp. 107-119.

A Review of Antifriction Materials and Design for Cryogenic Environments

R. L. Tobler

Advances in Cryogenic Engineering, Vol. 26

Proceedings of the 3rd ICMC, Madison, Wisconsin, August 21-24, 1979

A. F. Clark and R. P. Reed, editors

Plenum Press, New York (1980), pp. 66-77.

Effect of Particle Impact Angle on Strength Degradation of Glass

S. M. Wiederhorn, B. R. Lawn, and B. J. Hockey

J. Am. Ceram. Soc. 62, 639 (1979).

Erosion of Ceramics

S. M. Wiederhorn

Proceedings of the Conference on Corrosion/Erosion of Coal Conversion System Materials

A. V. Levy, editor

National Association of Corrosion Engineers, Houston, Texas (1979).

Hot Erosion of Glass

S. M. Wiederhorn and B. J. Hockey

J. Non-Crystal. Solids 38 and 39, 433-438 (1980).
Seminars for Staff and Guests

E. L. Brown

Metallurgy of High Strength Low Alloy Steels

October 12, 1979

Y.-W. Cheng

Significance of Defects in Powder Metal Parts

October 5, 1980

M. G. Dawes

Fracture Mechanics

July 29, 1980

R. deWit

Failure Criteria

October 9, 1980

R. J. Fields

Review of Deformation Mechanism and Fracture Mechanism Maps with an Introduction to Crack Growth Mechanism Maps

October 23, 1979

C. M. Fortunko

Projects in the Nondestructive Testing Field

November 9, 1979

T. Jessop

Characterization of Flaws by Ultrasonics

August 1, 1980

M. F. Kanninen

Current Research in Elastic-Plastic and Dynamic Fracture Mechanics

March 27, 1980

R. King

Applications of Acousto-Elasticity to Fracture Studies

December 13, 1979 ;

J. Klepaczko

Loading Rate Spectra in Fracture Dynamics

July 8, 1980

R. F. Krause, Jr.

Testing Cements for Geothermal Wells

April 8, 1980

0. L. Krivanek

Applications of Electron Energy Loss Spectroscopy in Materials

Science

April 25, 1980

15A
I. -H. Lin

Elastic-Plastic Fracture Mechanics

January 8, 1980

J. J. Mecholsky

Phase Separation and Improved Fracture Toughness of Glass

March 28, 1980

D. E. Passoja

Fracture and Fourier Transform Methods

February 1, 1980

D. P. Pope

Compositional Effects on the Creep Ductility of a Low Alloy Steel

March 11, 1 980

F. Shi

Elastic-Plastic Fracture Mechanics Analysis

February 28, 1980

A. Stuber

Geometry Effects on COD and J-Integral Toughness Values

July 10, 1980

C. E. Turner

Design Curves for EPFM

July 8, 1980

B. Udis

The Forthcoming NBS Study of the Costs of Fracture in the U.S.

Economy and Introduction to Input/Output Analysis

May 30, 1980

V. Vitek

Mechanisms of Brittle Fracture

May 27, 1980

W. W. Wilkening

Crack-Tip Stresses in a Dilating Material

October 26, 1979

D. S. Wilkinson

Models of Crack Growth at Elevated Temperatures

June 6, 1980

S. Y. Zamrik

Crack Growth under Multi axial Stress Field

May 23, 1980

in iimiBurnnr—ii"" •**”*“***
Special Reports

Refractory C02 Acceptor Gasifier Lining Reviewed

W. S. Brower, R. C. Dobbyn, and C. R. Robbins

Materials and Components in Fossil Energy Applications, U.S. Dept,

of Energy, No. 24 (1979).

Review of October 19, 1979 Meeting: ONR-NBS-C. S. Draper Lab Study

of Microcreep of Alloys

B. W. Christ

Progress Report to Office of Naval Research (April 28, 1980).

Review of June 11, 1980 Meeting: ONR-NBS-C. S. Draper Lab Study of

Microcreep of Alloys

B. W. Christ

Progress Report to Office of Naval Research (July 9, 1980).

Evaluation of a Failed Rupture Disk from a Rescue Relief Device

B. W. Christ

Failure Analysis Report to Mr. Harold Rhodes, U.S. Bureau of Mines,

Amarillo, Texas, NBSIR 80- (1980), in press.

Fracture Analysis and Material Evaluation of the Replacement Silver

Memorial Bridge, Point Pleasant, West Virginia . B. W. Christ

NBS Report (1980).

Fracture Mechanics Analysis of LCP Structural Components

T.-J. Chuang

Westinghouse AST Report (1980).

A Metallurgical Evaluation of Two AAR Ml 28 Steel Tank Car Head

Plates used in Switchyard Impact Tests

J. G. Early and C. G. Interrante

NBSIR 80-2039 (1979).

Proof Testing of Ceramics: II. Theory

E. R. Fuller, Jr., S. M. Wiederhorn, J. E. Ritter, and P. B. Oates

NBSIR 79-1944 (1979).

Atomic Modeling of Chemical Interactions at Crack Tips

E. R. Fuller, Jr., R. M. Thomson, and B. R. Lawn

NBSIR 80-2024 (1980).

Advanced Structures Development for Superconducting Magnets

M. B. Kasen, R. E. Schramm, and 8. A. Beck

Contract MIPR FY 1455 79000 503, Air Force Aero Propulsion Laboratory,

Wright-Patterson Air Force Base, Ohio (1980).

Testing Geothermal -Wei 1 Cements: Strength Measurements Following

Hydrotnermal Exposures, April 1979 Interim Report

R. F. Krause, Jr., and E. R. Fuller, Jr.

NBSIR 30-2099-1 (1980).
Testing Geothermal -Wei 1 Cements: Standard Practive, July 1979

Interim Report

R. F. Krause, Jr., and E. R. Fuller, Jr.

NBSIR 80-2099-2 (1980).

Testing Geothermal -Well Cements: High Temperature, High Pressure,

and Fluid Handling Facility, October 1979 Interim Report

R. F. Krause, Jr., and E. R. Fuller, Jr.

NBSIR 80-2099-3 (1980).

Testing Geothermal -Wei 1 Cements: Strength Measurements Following

Exposures to Simulated Geothermal Fluids

R. F. Krause, Jr., and E. R. Fuller, Jr.

NBSIR 80-2099-4 (1980).

Weldments for Liquid Helium Service

H. I. McHenry and T. A. Whipple

Materials Studies for Magnetic Fusion Energy Applications at Low

Temperatures-III

NBSIR 80-1627 (1980), pp. 153-165.

Fracture Control Practices for Metal Structures

H. I. McHenry and S. T. Rolfe

NBSIR 79-1623 (1979).

Materials Studies for Magnetic Fusion Energy Appl ications-III

R. P. Reed, editor

NBSIR 80-1627 (1980).

Vail Workshop

Materials Studies for Magnetic Fusion Energy Applications at Low

Temperatures-III

R. P. Reed

NBSIR 80-1627 (1980), pp. 425-437.

Proof Testing of Ceramics: I. Experiment

J. E. Ritter, P. B. Oates, E. R. Fuller, Jr., and S. M. Wiederhorn

NBSIR 79-1934 (1979).

Application of Fracture Mechanics in Assuring Against Fatigue

Failure of Ceramic Components

J. E. Ritter, S. M. Wiederhorn, N. J. Tighe, and E. R. Fuller, Jr.

NBSIR 80-2047 (1980).

Nonmetallics for Magnet Systems

R. E. Schramm, M. B. Kasen, H. M. Ledbetter, J. G. Hust, and A. F. Clark

Materials Studies for Magnetic Fusion Energy Applications at Low

Temperatures-III

NBSIR 80-1627 (1980), pp. 259-261.

Hardness Measurements on Three Sets of Submitted Beryllium-Copper

Parts

T. R. Shives

NBS Report (1979).
Tensile Tests of Stainless Steel Studs

T. R. Shives

NBS Report (1979).

Examination of Parts of Two Bolts for Cracks

T. R. Shives

NBS Report (1979).

Tensile Properties, Hardness Measurements, and Metal lographic

Examination of Submitted Electroformed Nickel Printing Plate

T. R. Shives

NBS Report (1979).

Characterization of DeLarue Plate Material

T. R. Shives

NBS Report (1979).

Tensile Properties and Hardness Measurements of Submitted Electroformed Nickel Printing Plate Number 45541-1

T. R. Shives

NBS Report (1979).

Tensile Properties, Hardness Measurements, and Metal! ographic

Examination of Submitted Electroformed Nickel Printing Plate

Number 45688-1

T. R. Shives

NBS Report (1979).

Examination of Failed Turnbuckle

T. R. Shives

NBS Report (1980).

Results of Shear Tests on Expanded Metal from the United StatesMexico Border Fence

T. R. Shives

Letter Report (1980).

Examination of Failed Eight-Inch Cast-Iron Pipe Natural Gas Main

T. R. Shives

NBSIR 80-1985 (1980).

Examination of Failed Six-Inch Diameter Cast-Iron Pipe Water Main

T. R. Shives

NBSIR 80-2036 (1980).

Examination of Expanded Metal Grating Material Used for Fencing

Along the United States-Mexi co Border

T. R. Shives

NBSIR 80-2043 (1980).
Examination of Three Submitted Turnbuckles for Cracks

T. R. Shives

NBS Report (1980).

Examination of Two Submitted Turnbuckles for Cracks

T. R. Shives

NBS Report (1980).

Examination of Failed Four-Inch Diameter Cast-Iron Pipe-Natural Gas

Main from Fort Payne, Alabama

T. R. Shives

NBSIR 80- (1980), in press.

Examination of Two Failed Bone Screws

T. R. Shives

NBS Report (1980).

Examination of Tension-Torsion Straps

T. R. Shives

NBSIR 80- (1980), in press.

Examination of Paint Strippers

T. R. Shives

NBS Report (1980).

Examination of Fan Shafts for NBS Plant Division

T. R. Shives

NBS Report (1980).

Examination of Aneurysm Clips

T. R. Shives

NBS Report (1980).

Examination of Failed Copper Tubing Resulting in Fire

T. R. Shives

NBS Report (1980).

Examination of Brazed Joints in a Bicycle Frame

T. R. Shives

NBSIR 80- (1980), in press.

Test Method for the Evaluation of Environmentally Assisted Stresscracking at Elevated Temperatures

J. H. Smith

NBSIR 80- (1980), in press.

Materials for Cryogenic Wind Tunnel Testing

R. L. Tobler

NBSIR 79-1624 (1979).

i JlL mimmil
Fracture Behavior of Ferrite-Free Stainless Steel Welds in Liquid

He 1 i urn T. A. Whipple, H. I. McHenry, and D. T. Read

Materials Studies for Magnetic Fusion Energy Applications at Low

Temperatures-III

NBSIR 80-1627 (1980), pp. 167-194.

Micromechanisms of Crack Growth in Ceramics and Glasses in Corrosive Environments

S. M. Wiederhorn, E. R. Fuller, Jr., and R. M. Thomson

NBSIR 80-2034 (1980).
Sponsored Conferences

NBS-DOE Workshop on Materials at Low Temperatures

Kiandra/Tal isman Lodge, Vail, Colorado

October 1979

31st Meeting of the Mechanical Failure Preventions Group—"Failure

Prevention in Ground Transportation Systems"

National Bureau of Standards, Gaithersburg, Maryland

April 1980

AWS-NBS Conference on Fitness-for-Service of Welded Structures

Indianapolis, Indiana

May 1980

ASTM Symposium, Fracture Mechanics Methods for Ceramics, Rocks, and

Concretes

Palmer House, Chicago, Illinois

June 1980

International Cryogenic Materials Conference (ICMC) on Nonmetallic

Materials at Low Temperatures-II

CERN, Geneva, Switzerland

August 1980

ASME Century 2 Special Symposium

St, Francis Hotel, San Francisco, California

August 1980

Critical Materials and Fabrications Issues for Pressure Vessels,

Piping, Pumps, and Valves, cosponsored with ASME

San Francisco, California

August 1980
Consulting and Advisory Services

Committee on Recommendations for U.S. Army Basic Scientific Research

(National Research Council)

S. M. Wiederhorn

Department of Energy Review Panel: Alternate Waste Forms for

Immobilization of High Level Radioactive Wastes

S. M. Wiederhorn

DOE Conductor Sheath Advisory Committee, Office of Fusion Energy

H. I. McHenry

DOT-Cambridge-Advisory Panel, Future R&D for U.S. Pipelines

R. P. Reed and H. I. McHenry

Evaluation of Executive Internship Program

B. W. Christ

Formulation of Welding COGENT Center for the Department of Commerce

Cooperative Technology Program with the American Welding Society

and Welding Research Council

H. I. McHenry and R. P. Reed

Geothermal Well Cementing Advisory Panel

E. R. Fuller, Jr.

Inspection of Steam Turbine Generator Components for the Breeder

Reactor Program

C. M. Fortunko

Interagency Coordination Group for the Application of Ceramics to

Heat Engines

S. M. Wiederhorn and N. J. Tighe

National Science Foundation Advisory Panel, Material Sciences

R. P. Reed

Review of Structural Integrity of the Pipeline Used in Strategic

Petroleum Reserve of Bryan Mound, Texas, for the Department of

Energy

R. P. Reed and H. I. McHenry

Source Evaluation Board, The Economic Aspects of Fracture in the

U.S. Economy, NBS

R. P. Reed, Chairman; B. W. Christ and J. H. Smith, Members

1
.

'

! u

—

POLYMER SCIENCE AND STANDARDS DIVISION (563)

Ronald K. Eby, Chief

Leslie E. Smith, Deputy Chief

S. M. Thomas, Administrative Assistant

B. M. Weeks, Secretary

In the seven decades since Leo H. Baekeland introduced the first

commercial synthetic plastic produced entirely by the reaction of small

molecules, polymers have left little of our culture and technology

untouched. We have moved rapidly into an age in which an overwhelming

number of humanity's needs are served by polymers. The increase in

production and use has been spectacular; the volume of polymers produced

last year exceeded that of steel. Recent summaries show that polymers

research already accounts for about forty-seven percent of the total

industrial R&D expenditure for metals, polymers, and inorganic materials.

Among these materials, polymers also constitute about thirty-nine percent

of the value added by manufacture (a measure of the relative economic

importance of manufacturing among industries), forty-five percent of the

number of scientific publications, and thirty-nine percent of the 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 productivity through their economy

ease of fabrication, and useful properties such as low density, corrosion

resistance, and toughness. They are energy efficient, with the largest

volume polymer, polyethylene, using twenty-eight percent of the energy

per unit volume required by steel for the conversion from raw to refined

material and yielding further savings in processing and shipping.

Polymers have entered increasingly sophisticated and demanding

applications. Polyvinyl i dene fluoride films are used as electromagnetic

transducers in high fidelity systems. Structural parts of aircraft are composites with a polymer matrix. Polyurethane elastomers are used to

pump blood in circulatory assist devices. The list of such examples is

very long, encompassing trends for the increased use of polymers in

packaging, construction, transportation , energy, electronics, information

handling, clothing, appliances, dentistry, and medicine. Since polymer

technology is on the steep part of the learning curve, these trends

create new needs for concepts, measurements, standards, and data that

can be used to insure reliable performance in use, processing, and other

phases of the material cycle.

To identify the key needs, the managers of the Polymer Science and

Standards Division make structured visits to Government and industrial

laboratories. Recent visits have included Bell Labs, Du Pont, Army R&D

Command, General Motors, Boeing, and Lawrence Livermore. Surveys have

been conducted in the areas of durability, processing, and comcosites.

These and other contacts with exDerts in industry, trade associations,

standards associations, Government, and academia insure that the Division
efforts are directed toward fostering the effective use of polymers in

solving national problems cited by our Director as appropriate for NBS.

These include the growth of industrial productivity, prudent utilization

of energy sources, a reasonable system for regulation of the effects of

technology, and a wise policy of materials utilization.

The Division has used its survey activities as a basis for participating

in budget initiatives to secure the resources necessary to meet the

emerging needs. For the budget cycles currently active, programmatic

initiatives that include additive migration, composites (biaxial orientation),

blends, ionic conduction, and thin films are under consideration.

Competence building initiatives on the science of collapse transitions,

electronic conduction, high field NMR, and electron microscopy have been

prepared.

The present activities are associated into areas concerned with

mechanical reliability in load bearing applications, chemical durability,

and lifetime prediction including the migration of protective additives,

characterization methods and standards for molecular composition and use properties, dielectric properties, and electrical conduction, and reliable

dental and medical materials. Substantial cooperative efforts are conducted with the Food and Drug Administration, the Department of

Defense, the National Institutes of Health, the American Dental Association,

the Department of Energy, the Bureau of Engraving and Printing, and

others. All the efforts lead the scientists in the Division into productive

examination of those properties of polymers 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.

The Division has had another productive year. It has fulfilled

requests from other agencies and other NBS programs for $2.5 M worth of

research services and has produced over seventy publications (about

forty percent of the Center total). Seven members of the staff received

outside recognition, and a similar number received Department of Commerce

Awards. Three strong new staff members have been selected in the areas

of charge conduction, chemical stability, and fracture. These include

two highly qualified women professionals raising the Division's percent

of minority and women full-time permanent professionals to twenty percent.

In the following pages, the activities of the Division are presented

formally in five tasks, each described separately:

12132 POLYMER STANDARDS FOR CONTROL AND EQUITY

12135 TESTS, STANDARDS, AND CHARACTERIZATION FOR MANUFACTURING

AND DURABILITY OF DENTAL AND MEDICAL MATERIALS

12136 MECHANICAL DURABILITY OF POLYMERS FOR DESIGN AND USE

12138 MIGRATION AND THE DURABILITY OF POLYMERS

12139 DIELECTRIC AND PIEZOELECTRIC PLASTICS PERFORMANCE
POLYMER STANDARDS FOR CONTROL AND EQUITY

Task 12132

This task provides molecular and gas transmission standard reference

materials (SRM's) to a $30 bill ion/year plastics and elastomers industry.

Molecular SRM's are used extensively in industry to calibrate gel permeation

chromatographs (GPC's) which are used routinely to measure polymer

molecular weights and molecular weight distributions. The latter are

the most important physical properties in determining a polymer's processability and its ultimate performance.

Our basic mission is to maintain and extend our expertise in polymer

physical characterization. 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. Some of these activities during

the past year include:

o production of a new, narrow- fraction polystyrene standard, SRM

1479 (M ^ 10 6

) W

o completion of a new computerized gas permeation measuring

facility

o continued development of a new state-of-the-art, self-calibrating

GPC; self-calibration is achieved by making simultaneous light

scattering measurements at nine angles on the GPC effluent

o characterization, by intrinsic viscosity and light scattering

measurements, of a ultrahigh molecular weight polyethylene

used in prosthetic devices

o development of the concept that all dilute polymer solutions

possess certain "universal" physical properties characteri zabl

e

by a single excluded volume parameter

Standards For Gas Transmission Rate Measurements

Subtask 1 of Task 12132

J. D. Barnes

Engineering work on the new NBS automated manometric permeation

measuring facility is substantially complete. Operational trials and

calibration measurements are currently under way. The efforts expended

on the design of safety interlocks, control circuitry, interfaces, and

operating software have provided valuable experience for future ventures

in measurement automation. There are some improvements which must be

made to the temperature controls and the vacuum manifold before routine

experiments can be conducted.

ii~mn«nniMinnmMNIIIIinaillMM
Recent trends in gas transmission measurements have been toward

instruments that are simpler to manipulate and more selective than the

manometric technique. Our experience with our automated measuring

system indicates that the manometric method is capable of considerable

improvement at a relatively modest cost. The time scale of the measurements

is determined completely by the diffusion coefficient of the gas, the

thickness of the film being measured, and, in some instances, the time

scale of concomitant viscoelastic processes. These factors are independent

of the technique used to measure the transport properties. The optimization

that is built into the controlling software we have devised does, however,

result in significant time savings because there is no need for a human

decision regarding the recovery of the system from the previous measurement

cycle or the achievement of a steady state. The experience should prove

useful to those who wish to devise simpler instruments for use in quality

control applications.

The new facility was used to investigate the feasibility of adding

transmission rates for He, N 2 , and C02 to the certificate for gas transmissi

SRM 1470, which is currently certified only for oxygen. These preliminary

experiments demonstrated that the apparatus obtains valid data for these

gases. An experimental design has been formulated for carrying out the

measurements of transmission rates of He, N 2 , 0 2 , and C0 2 at a number of

pressures and temperatures as required for an SRM certificate. OSRM is

providing support for these measurements, and it is expected that they

will be complete by the third quarter of FY81. The measurements of 0 2 permeance are being redone because it is expected that some aging of the

material has taken place during storage.

Correlations which are possible when four different gases with

different molecular sizes and different thermodynamic properties are measured on the same sample should provide a clearer picture of the gas

transport mechanisms in this polymer.

The preliminary experiments revealed, as expected, that C0 2 exhibits

the phenomenon of partial immobilization in SRM 1470. New models must

be devised for fitting the experimental data, and the ramifications of

partial immobilization on the mechanical properties and morphology of

the polymer must be explored before we can specify the best way to use SRM 1470 in calibrating C0 2 permeance measuring apparatus.

A publication describing the construction and operation of the

automated manometric permeation measuring apparatus will be prepared as time becomes available once the apparatus is being used for routine

measurements.

After completing the recertification of SRM 1470, we expect to

evaluate candidate materials for an SRM with transmission rates approximate!

50-100 times that of SRM 1470. These materials are needed because

existing instrumental methods perform poorly at high gas fluxes. It is

likely that minor changes will have to be made in our interfaces in

order to accomodate the higher data collection rates found in this work.
Work is continuing on devising a system of units that is both

compatible with SI and scientifically consistent. The SI base units of

moles, meters, pascals, and seconds are the starting point. While the

logic of this scheme is recognized, there is considerable resistance

from users of the wide variety of customary unit systems.

A publication outlining ways in which SRM 1470 can be used to

improve the performance of existing gas transport measurement systems is

in preparation.

NBS played an influential role in promulgating a substantially

revised edition of ASTM D-1434, the standard method for measuring gas

transmission rates. The new document features more consistent terminology,

an improved set of SI units, the use of safer equipment, the use of

SRM 1470 for calibration checking, and a clearer derivation of the

equations used to fit the data.

ASTM Activities

Subtask 2 of Task 1 2132

J. D. Barnes

J. D. Barnes serves as Chairman of ASTM Subcommittees F-2.30 (Test

Methods) and F-2.93 (Statistical Matters) of ASTM committee F-2 on Flexible Barrier Materials. Subcommittee F-2.30 is currently working on test methods relating to materials characterization, barrier properties,

sealing and bonding properties, and additive migration. Subcommittee

F-2.93 is responsible for providing statistical assistance to all task

groups operating within F-2. The design and analysis of i nterl aboratory

testing programs are the major forms this assistance takes.

Dr. Barnes and Dr. John Mandel conducted a workshop on Interl aboratory

Testing during the February 1980 ASTM Committee Week in San Diego,

California. Over 100 individuals from ASTM Committees D-20, F-2, and

F-17 participated. Interl aboratory testing programs are the principal

technique used to validate ASTM Methods of Test.

Dr. Barnes is also a member of ASTM Committee D-20 (Plastics) and

its subcommittees on Plastic Film and Sheeting D-20. 19, Olefin D-20, and

F-2. Dr. Barnes led the task group that recently promulgated a revised

version of ASTM D-1434, the standard Method of Test for Gas Transmission

Properties of Plastic Film and Sheeting.

Self-Calibrating Gel Permeation Chromatography

Subtask 3 of Task 12132

P. H. Verdier

Gel permeation chromatography (GPC) 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 calibrants 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, an example of which is commercially available, attempt to circumvent the

need for calibrants 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 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.

The instrument has been designed, and construction of its mechanical

components is scheduled for completion by the end of the current fiscal

year. The dedicated minicomputer system has been installed, with a video display which will permit real-time plotting of the angular dependence

of the scattering. In the coming fiscal year we expect to assemble and

align the instrument and begin testing.

Dynamics of Polymer Chains

Subtask 4 of Task 12132

P. H. Verdier, D. E. Kranbuehl

The dynamic behavior of polymer chains is important for two reasons.

First, the principal methods used to estimate molecular weight, and in

particular gel permeation chromatography , the only method available at

present for estimating distribution in molecular weight, are dynamical,

non-equilibrium 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 calibrants of known molecular

weight is required. Improvements in the theory could reduce or even remove the need for calibrants, allowing the determination of molecular

weight distribution of polymers for which calibrants are not available.
Second, 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.

We have previously shown that for our simple chain models, selfentanglement effects lengthen the longest relaxation times of the chains

by a factor proportional to about the first power of chain length.

However, our models differ from polymer chains in solution in (at least)

two obvious respects: the chains are constrained to lie upon a lattice,

and motion from one configuration to another is accomplished solely by a series of purely local chain motions. Theoretical work carried out

elsewhere appeared to predict a much weaker dependence of the lengthening

of relaxation times upon chain length than we had found, leading to the

suggestion that our results were artifacts arising from special constraints

in the local chain motions we had employed. We subsequently obtained

results for chains with modified rules of motion free of these constraints

and showed that the suggestion was incorrect. We have now completed a series of studies of the effects of local bead motion constraints and of

the type of lattice employed upon relaxation behavior. The results show

that although self-entanglement effects are weakened by the removal of

local bead motion constraints, they are still much stronger than current

theoretical predictions. Further, the self-entanglement effects are essentially the same on simple cubic, body-centered cubic, and face-centered

cubic lattices, suggesting that similar behavior may be obtained when

the chains are removed from the lattice. Therefore, we are preparing to

study the motion of chains free of lattice constraints (though still

employing local bead motions). Testing of the programs is currently

under way. We expect that it will be completed and preliminary results

obtained by the end of the current fiscal year; the study should be

completed in the coming fiscal year.

Additional work planned for the coming year will proceed along two

lines. First, there is at present an unresolved disagreement in the

literature regarding the interpretation of the time-corre! ati on functions

obtained for flexible chain molecules in the quasielastic 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. It appears that by direct simulation we may be able to

resolve the disagreement, which will increase the value of measurements

made by this relatively new techniaue. Second, as a step in the direction

of investigating melt properties, we will extend the simulation studies

to non-dilute solutions.
Static and Dynamic Scattering From Polymers

Subtask 5 of Task 12132

C. C. Han

Scattering techniques are most effective in measuring space as well

as space-and-time correlations of polymers in both solutions and bulk

states. Our effort has been centered around the universal approach of

temperature, molecular weight, and concentration dependence of static

and dynamic properties of polymers. We investigate and compare theoretical

predictions based on modern scaling concepts as well as conventional

theories to our experimental results from the small angle neutron scattering

(SANS), light scattering, and quasi elastic light scattering experiments.

In static scattering, spatial correlations of monomer densities in

q- Fourier space are measured directly. With the SANS facility at NBS,

it is possible to measure single chain properties in the range of

0.01 < q

< 0. 1 0 1 from dilute solution to the bulk state through

deuterium labeling. Also, with the high concentration labeling technique

which we developed last year, it is possible to study single chain

properties over a wide range of concentrations using a medium flux

reactor such as the NBS reactor.

On the other hand, dynamic scattering, such as quasi elastic light

scattering, uses the photon correlation technique to measure the time

correlation function of scattered light from polymer solutions. This

time correlation function at any momentum transfer, q, is related to the

intermediate scattering function, S(q,t), which is a Fourier transform

of the space correlation function of monomer pairs. Therefore, in

principle, measurement of S(q,t) can provide not only a measure of the

properties associated with the equilibrium distribution of polymer

segments such as the radius of gyration, R^, or the statistical segment

length, but can also measure physical properties associated with the

time evolution of polymer segment distributions, such as the hydrodynamic

radius, R^, or the hydrodynamic interaction strength.

Our most recent efforts have been centered on the development of

theories for the intermediate scattering function, S(q,t), and the

characteristic frequency, Q(q), for polymer solutions. Such theories

are essential for the i nterpretation of quasielastic light and neutron

scattering data. Our theory includes both temperature and molecular

weight dependence specifically. We have also successfully applied this

theory to a different characterization technique, intrinsic viscosity.

Interpretation of Scattering Experiments on Polymer Solutions

Subtask 6 of Task 12132

A. Z. Akcasu 1

, M. Benmouna 1

, C. C. Han

’•University of Michigan

Interpretation of dynamic scattering experiments requires, ideally,

a theory that can predict the intermediate scattering function, S(q,t),
and a chain model consistent with the chemical structure of the polymer.

Unfortunately, exact expressions of S(q,t) are available, at present,

only for single unperturbed (0-condition) gaussian chains without hydrodynamic

interaction (Rouse model), or, in the infinite chain limit, with hydrodynamic

interaction and preaveraged Oseen tensor (Rouse-Zimm model). In this

sense, a complete interpretation of scattering experiments on polymer

solutions is an unsolved problem. By using linear response theory, we

have been able to obtain closed form expressions for S(q,t) of both

linear and circular chains for Rouse and Rouse-Zimm cases in the infinite

chain limit. Also, we can express S(q,t) for finite linear chains in

the Rouse limit and for circular chains in both Rouse and Rouse-Zimm

limits in closed form. All these can be compared with the method of

eigenfunction expansion and the method of solving diffusion equations

directly. Advantages of our current scheme have been demonstrated. In

the case where an exact solution of S(q,t) can not be obtained, the

characteristic frequency, Q(q), which is the initial slope, and defined

by

CKq) = -lim dS*jg'

t}

t->0 can be calculated. The temperature and concentration dependence of Q(q)

in terms of "blob model" chain statistics can be calculated not only for

the intermediate scaling region, but also for the upper and lower transition

regions where information about polymer chain parameters such as radius

of gyration, R^, statistical length, a, and hydrodynamic interaction, B, can be extracted.

Temperature, Molecular Weight, and Concentration Dependence of

Chain Dimensions Around 9-Temperature

Subtask 7 of Task 12132

S. J. Bai 1

, D. J. Lohse2

, I. C. Sanchez, C. C. Han

X IAP assignment from University of Michigan

2 NRC/NA$ Postdoctoral Associate

Chain dimension and the q-dependence of the single chain scattering

function, S(q), are being studied at various temperatures and concentrati ons with different molecular weights by SANS. Experimental results will be

compared with various theroetical predictions. The difference between

dimensions in dilute solution at the 9-temperature and in the bulk state

will be studied.

Concentration Dependence of Diffusion Coefficient at Various

Molecular Weights and Temperatures

Subtask 8 of Task 12132

A. Z. Akcasu 1

, C. C. Han

University of Michigan

Experimental results of the concentration coefficient, k^, of the

diffusion coefficient, 0, of polymers in dilute solution have been
investigated and compared with various theoretical predictions. The

negative kg for small molecular weight and low temperature and the

positive kg for large molecular weight and high temperature can be

understood through model calculations which include chain swelling and

intermolecular potential. The molecular weight independent, but negative,

concentration dependence of D at 9- temperature indicates the contributions

of overlapping pairs of molecules. Chain expansion at the 9-temperature

due to chain overlap is implied.

Dynamic Structure Factor, S(q,iu), of Dilute Polymer Solutions

Subtask 9 of Task 12132

A. Z. Akcasu 1

, C. C. Han

University of Michigan

Most of the quasi elastic neutron and some of the quasi elastic light

scattering experiments are performed in the frequency domain due to the

character!' sties and availability of experimental facilities. The extraction

of the character!' Stic frequency Q(q) from S(q,w) data poses difficulties

similar to those in time domain analysis. Although S ( q ,u>) is just the

Fourier transform of S(q,t), it is not straightforward to obtain an analytical expression for S(q,uu) even in the cases where S(q,t) is

available. On the other hand, it is not fruitful to perform numerical

inverse Fourier transform on the experimental S(q,uj), due to the finite

data set and lack of precision. We have, therefore, investigated the

shape of S(q,w) numerically for various cases to facilitate the extraction

of Q(q) from S(q,u)) directly in both light scattering and neutron scattering

experiments.

Domain Structure of Block Copolymers and Characterization of

Polyelectrolyte

Subtask 10 of Task 12132

I. Noda 1

, T. Hashimoto2

, S. J. Bai 3, D. B. Minor, and C. C. Han

1 Nagoya University, Japan

2 Kyoto University, Japan

3

1 AP assignment from University of Michigan

Preliminary study of the domain interface structure of star shaped

polystyrene-polyi soprene block copolymers has been carried out by neutron

scattering. Data analysis is in process, and further experiments are in

preparati on.

Also, the character!' zation of polyacrylic acid by combined measurement

of SANS and LS under various salt concentrations and charge densities is

under way.

172
Development of a Digital Lock-in Light Scattering Photometer,

and the Measurement of Polystyrene 1479 and UHMW Polyethylene

Subtask 11 of Task 12132

D. B. Minor, H. L. Wagner, C. C. Han

A state-of-the-art light scattering photometer has been developed

for the purpose of measuring the molecular weight of polymer SRM's and

ultra high molecular weight synthetic implant materials. This photometer,

which utilizes photon counting and digital lock in, has been tested by

measuring previously certified SRM's.

A temperature controller has been installed and tested for polyethylene

measurements at elevated temperatures. Measurement of polystyrene 1479

(M ~ 10 6

) in toluene has been completed for SRM certification. Measurements

of ultra high molecular weight polyethylene is currently under way.

Configurations of Polymer Chains

Subtask 12 of Task 12132

R. J. Rubin

A review of applications of the theory of random walks to polymer

chain configurations is being prepared with G. H. Weiss of the National

Institutes of Health. This review also includes a number of new results:

(1) a new connection has been established between random walk probability

distributions and a generating function obtained by Rubin [J. Chem.

Phys. , 43, 2392 (1965)] for calculating configurational properties of a polymer chain attached to an adsorbing (or repelling) solution surface.

In particular, eq. (26) of that paper can be expanded as a power series

q 20

in e . The coefficient of e is the probability that a random walk

originating in the solution surface layer will return s-1 times to the

surface in an N-step walk. Random walk probability distributions of

this type are considered by E. W. Montroll and G. H. Weiss, [J. Math.

Phys., 6, 167 (1965)]. When Rubin's eq. (26) is viewed in this way,

random walk configurations are classified according to the number of

visits, s, to the surface layer. Then the total probability is the sum

of the weighted probabilities where the weight function is proportional

2 0

to e , a Boltzmann weight factor. (2) The treatment of a polymer chain

between two plane solution surfaces given by DiMarzio and Rubin [J.

Chem. Phys., 55, 4318 (1971)] has been extended to treat polymer chains

of finite length. All the results obtained by DiMarzio and Rubin pertain

to the limit in which the ratio of the extended chain length to the

separation between the bounding planes is large compared to uni ty. One

quantity of particular interest is the average step density as a function

of position between the solution surfaces. For random walks of N steps,

configurations can be classified according to the number of visits, r,s,

to the two solution surfaces. The subclass of N-step random walks in

which each surface is visited at least once is identical to the subclass

of N-step random walks whose span is the same as the distance between

the solution surfaces. The calculation of the step density for N-steo

random walks with a given span is in progress.

173
In the absence of the complicating effects of interaction with

surfaces, probability distribution functions of configurations of long

chain molecules can be modeled by solutions of a random flight or diffusion

equation. However, it is known from studies of lattice models that if

the energy of attraction between links of the polymer chain and the

surface becomes sufficiently high, then there is a discontinuous collapse

of the chain on the surface. The description of such discontinuous

behavior within the framework of a diffusion equation appears to present

technical difficulties.

DeGennes [Reports Prog, in Phys. , 32, 187 (1969)] has proposed that

the appropriate boundary condition in the case of a "weakly adsorbed"

chain is the mixed boundary condition, & 3G/3x + mG = 0 at the solution

surface, where G(x,N) is the solution of the diffusion equation. DeGennes

drew the analogy between his suggestion for the boundary condition of

the diffusion equation and the treatment of the bound state of the

deuteron. We have approached the question of the appropriate boundary

condition for the diffusion equation in a complementary way. Starting

with the lattice random walk equations in Rubin [J. Chem. Phys., 43,

2392 (1965)], we have assumed that not only the surface layer is modified

by a factor e , but each of the first & layers are modified by this

factor. We then go to the random flight limit in which the lattice

equations are replaced by diffusion equations.

For this special model, we see how to establish a correspondence

between the solution of a diffusion equation with a source (sink) term

in an adsorbing (repelling) layer with an absorbing boundary condition

and the solution of a diffusion equation with the mixed boundary condition

proposed by DeGennes.

The Characterization of Ultra-High Molecular Weight Polyethylene

For Synthetic Implants

Subtask 13 of Task 12132

H. L. Wagner, J. G. Dillon 1

1 Guest worker, Food and Drug Administration

The development of new or modified methods for characterizing the

molecular weight and molecular weight distribution of ultra high molecular

weight polyethylene (UHMWPE) has continued with major emphasis on work

on the low shear viscometer. The light scattering apparatus has been

readied for high temperature operation, and a new fractionation bath is

being assembled.

Because of problems with wobble of the rotor and poor reproducibi 1 ity,

major modifications were made in the viscometer design. As a result of

these changes, it is now possible to reproduce solvent readings to

within one percent, and the wobble of the rotor is no longer noticeable

at those periods of rotation required for viscosity number determinations.
A problem remains with reproducibility for solutions of UHMWPE

which appears to be due primarily to solution preparation. If severe

enough means are not employed to dissolve the polymer, complete solution

is not obtained. If too severe a method is used, on the other hand,

degradation occurs. Considerable effort has gone into finding a satisfactory

technique, and a promising one is now being evaluated. It consists of

heating the solution at 150 °C under nitrogen for one hour with just

enough gentle swirling to keep the polyethylene particles separated

before melting. This avoids the formation of globs which are very

difficult to dissolve.

Viscosity values in decal in in the low shear viscometer are some

twenty percent higher than in tetralin, a surprising result, since if

the Mark-Houwink equations (evaluated for lower molecular weights) are extrapolated to higher molecular weights, very similar viscosity numbers

would be expected for these solvents. It is also found that these high

values in decal in decrease at the rate of two to three percent per hour

for the first few hours, a change which does not occur with tetralin or with either solvent in the ordinary capillary viscometer, which operates

at much higher shear rates. Whether these differences are due to degradation

or some other phenomenon has not been determined.

Once the technique for obtaining low shear viscosity numbers is

established, fractionation will begin in order to obtain fractions for

establishing the Mark-Houwink equation for UHMWPE.

Cell Model Theory of Polymer Solutions

Subtask 14 of Task 12132

I. C. Sanchez, D. J. Lohse 1

X NRC/NAS Postdoctoral Associate

An incompressible, statistical thermodynamic theory of a polymer

solution is formulated which takes into account concentration inhomogeneities.

A generalized cell model is used as the basis for the new polymer solution

theory. Closed-form, parametric equations are obtained for solvent and

polymer chemical potentials which only reduce to classical (FI ory-Huggi ns

)

potentials when concentration homogeneity is assumed. In a good solvent,

the calculated second virial coefficient decreases with molecular weight

(M 1 5 dependence) in good agreement with available experimental data.

In dilute solutions, chain dimensions can be analytically determined;

the well-known Flory excluded volume equation is obtained. The most

important parameter in the cell model is the average number of chains/cell,

For semi-dilute solutions (A >> 1), it is shown that several important

scaling results are recovered from a simple scaling hypothesis for
Interfacial Tension Theory of Low and High Molecular Weight Liquid

Mixtures

Subtask 15 of Task 12132

I. C. Sanchez, C. I. Poser 1

1 Guest Worker, University of Massachusetts

A generalized van der Waals or density gradient theory of interfaces

has been combined with a compressible lattice theory of homogeneous

fluid mixtures. Binary liquid- vapor and 1 i quid- 1 i quid systems are treated. For non-pol ar low molecular weight mixtures, liquid-vapor

tensions are calculated as a function of composition with an error of

less than five percent. These calculations involve no adjustable parameters;

all required parameters are determined from pure component properties.

For polymer solutions, it is usually necessary to introduce an adjustable

interaction parameter to accurately correlate liquid-vapor tensions.

Approximate equations for the interfacial tension and thickness between

two immiscible, high molecular weight polymer liquids have been obtained.

These equations are a function of a single interaction parameter; when

this parameter is chosen to match experimental tensions, interfacial

thicknesses of 1 to 5 nm are obtained. To assess the importance of

compressibility effects, the interaction parameter can be chosen so that

the heat of mixing is zero for an incompressible system. This "pure

compressibility approximation" works well for polymer pairs with relatively

low interfacial tensions. The most serious deficiency of the theory is

that i ntramol ecul ar correl ational effects present in long polymer chains

are only crudely approximated.

Configurational Properties of Comb-Branched Polymers

Subtask 16 of Task 12132

F. L. McCrackin, J. Mazur

Mean-square radii of gyration were computed for comb-branched

polymers simulated on a cubic lattice by chains with both excluded

volume and attractive energies between nonbonded segments of the polymer.

The ratios, g, of the radius of gyration of a comb-branched polymer to

that of a linear polymer of the same molecular weight at the theta point

were found to be larger than the g ratios calculated by the unrestricted

random-walk model of the polymer. These calculated g ratios showed

better agreement with experimental measurements than did those calculated

by the random walk model.

The radii of gyration of the backbones and the expansion factors of

the comb-branched polymers were also calculated. The radii of gyration

of the backbones at the theta condition were greater than that of linear

polymers, in contradiction to the random walk model which requires that

they be equal. The calculated expansion factors were less than that of

linear polymers, also in contradiction to the random walk model.

176
Rubber and Rubber Compounding Standard Reference Materials

Subtask 17 of Task 12132

G. W. Bullman, G. B. McKenna

The process of streamlining the NBS Rubber Program is continuing in

response to reduced resources available for this program. As part of

this reduction, rubber and rubber compounding Standard Reference Materials,

for which NBS serves primarily as a warehouse facility, are being removed

from the SRM list as inventories are exhausted. In addition, several

materials are being removed from the list due to poor sales. These SRM

deletions are being coordinated with ASTM Committee D-ll on Rubber and

Rubber-like Materials and Committee D-24 on Carbon Black to assure an orderly change in the ASTM standards and within the rubber industry.

In order to serve industry's needs for rubber SRM's with our reduced

resource base, we are maintaining inventories of materials which industry

(through ASTM) has indicated are important, even though NBS's primary

function for these materials is to serve as a warehousing facility. For

example, we are recertifying N-tertiary-butyl-2-benzothiazole sulfenamide

[SRM 381(d), a rubber accelerator] in order to maintain inventories of

this material. In addition, where standards involve certification of

basic physical properties, we are assuring the renewal of the SRM's as necessary, and where the need is indicated, we are issuing new SRM's.

Thus, last year we recertified the butyl rubber SRM 388(k) which is used

as a Mooney Viscosity Standard. During this year, we have completed the

work necessary for procurement of a new Mooney Viscosity Standard, thus

extending the range of Mooney Viscosity Standards available- to the

rubber industry.

I

I

I

I

177

TESTS, STANDARDS, AND CHARACTERIZATION FOR MANUFACTURING AND DURABILITY

OF DENTAL AND MEDICAL MATERIALS

Task 12135

The objective of this research is to contribute to dental health

care through development of better performing materials and test methodology

and standards appropriate thereto. Materials research and techniques

are pursued with the goal of developing adhesive composite restorative

materials of greater durability and wear resistance, and improved base

metal alloy alternatives to the costly gold alloy prostheses. 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 and for defining the interactions that

occur thereon.

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 R&D command.

Medical materials research is guided by close interaction with the Food

and Drug Administration's Bureau of Medical Devices and the ASTM F-4

Committee (Medical and Surgical Materials and Devices).

Dental Composite, Resin, Sealant, and Cement Chemistry and Development

Subtask 1 of Task 12135

G. M. Brauer, J. M. Antonucci , J. W. Stansbury, R. E. Dehl

,

J. M, Cassel , R. L. Bowen 1

, H. Argentar 1, D. W. Misra 1

, T. Chen2

Research Associate, American Dental Association

2 Guest Worker, Food and Drug Administration

Current efforts are directed toward upgrading the quality of composite

restorative materials with regard to color and storage stability, toxicity

effects, adhesiveness, and durability. Structure-property relationships

are developed and used as guides to the synthesis of new polymerization

accelerators for dental resins. Laboratory synthesis and evaluation

efforts have developed an amine accelerator with a reactivity that

permits a threefold reduction in the concentration of accelerator required.

The generic biocompatible nature of the amine, combined with the reduced

concentration required, indicates that dimethyl ami nophenyl acetic acid

will prove a valuable dental resin component. Strong interest has been

expressed by the dental manufacturers in a second amine developed to

accelerate the curing of denture base materials without imparting any

color. Efforts have continued to make a potentially very useful peroxide

ascorbic acid copper initiator accelerator system more practicable.

Invited papers covering initiator accelerator systems for acrylic resins

and composites and new monomers for use in dentistry were presented at

the Symposium on Biomedical and Dental Applications sponsored by the ACS

in Houston.

179

mmam
The mechanism of reinforcement of dental composite restorative

materials through silane inorganic fillers is being examined as a means

of improving the durability of such materials when used in stress bearing

applications. Bond formation between the silane coupling agent and the

filler is monitored by infrared analysis and indicates that addition of

selected amines to the carrier solvent improves the coupling effectiveness

of the silane.

A major problem encountered in the investigation of the properties

of dental composite restorative materials is the absence of quantitative

analytical methods for determining chemical composition in the solid

state. Infrared (IR) spectroscopy, which is widely used to analyze

chemical composition, is useful for studying dental composites, but

Fourier Transform capability is required because of light scattering and

absorption by the glass filler. Measurements are currently being made

with the new IR equipment of the Center for Materials Science. Recently

we have performed some Raman spectroscopic analyses of dental composites

and the various components of the composites, using the spectrometer in

the Center. Preliminary results indicate that the Raman technique will

circumvent many of the problems encountered with infrared analysis and

will allow at least semi quantitative estimates to be made of chemical

groups such as unreacted carbon/carbon double bonds in the polymerized

composite matrix. Further work is in progress, as we use the Raman

technique to analyze dental composite materials prepared by different

experimental procedures. We are also investigating NMR as a means of

studying the state of molecular motion in these presumably highly cross- linked resin systems. It is expected that the information thus obtained

will be useful in evaluating the performance of dental materials.

At the request of the Council on Dental Materials, Instruments, and

Equipment of the American Dental Association, a status report for publication in the Association's Journal was prepared on the desirability of

using radiopaque plastics in dentistry.

Development of Adhesive Bonding Technique

Subtask 2 of Task 12135

G. M. Brauer, R. L. Bowen 1

, J. M. Antonucci , D. W. Misra 1

, J. W. Stansbury, J. M. Cassel

Research Associate, American Dental Association

Strong mechanical bonding of acrylic resins to enamel surfaces can

be obtained through acid etching of such surfaces, followed by resins or composite formulations capable of wetting and penetrating the newly

created surfaces. Such treatment has not been applicable to surfaces of

dentin and has not been entirely successful in the caries preventive

application of pit and fissure sealants to the occlusal enamel surfaces

of chi 1 dren 1 s teeth.

One approach to adhesive bonding that is being pursued is the

development of multifunctional molecules designed to interact with

calcium on the tooth surface and with the in si tu polymerizing dental

ISO
resin. Using the diametral tensile strength of hydroxyapatite filled

composites as a measure of the adhesiveness where the filler is coated

with the coupling agent of interest, several surface active polymerization

activators appear to offer promise.

One new direction taken recently has been the development of physiological buffer solutions capable of dissolving the smeared surface

layers on cut dentin and of isotonic mordant solutions to improve bonding

sites. Isotonic methacrylate monomer formulations containing adhesion

promoting coupling agents have been developed that should not induce

osmotic insult to odontoblasts and pulp tissues.

Wear Resistance and Mechanical Properties of Dental Materials

Subtask 3 of Task 12135 i

W. Wu, J. E. McKinney, J. M. Cassel , E. Cobb 1

1 Guest worker, Georgetown University Dental School

In a study of the mechanisms governing both clinical and laboratory

wear of dental restorative materials, a silver staining technique has

been developed to examine structural changes in the damage zone immediately

beneath the worn surface. Worn specimens are cross sectioned and examined

by microscopy for quantification of the micro defects. Initially,

clinically worn specimens are being provided through a guest worker from

Georgetown University Dental School. The results to date suggest that

greater efforts to introduce erosion effects into accelerated wear

testing are required. Equipment to accomplish this has been designed

and assembled.

With pin-on-disc wear instrumentation we have demonstrated that

wear is very irregular, varying by a factor of two over different positions

on the same specimen. The data support the use of durapatite, a form of

sintered hydroxyapatite, as an appropriate substitute for human tooth

enamel for i_n vitro measurements. However, microdefect analysis of i_n

vivo and i_n vi tro worn specimens brings into question the relevancy of

i n vitro data generated with enamel pins. The effect of loading on the

accelerated wear results generated on dental composite specimens with

hard (durapatite) and softer (steel) pins is under study. Initial

transient wear regions indicate the presence of surface layers that

inhibit wear of certain metals and alloys. These surface layers reform

during periods of inactivity. Since this phenomenon may play a very

important role in enhancing i_n vi vo durability of amalgams and other

dental alloys, efforts are in progress to determine surface compositions

by means of Auger Electron Spectroscopy.

Auger Electron Spectroscopy (AES) Applied to Wear Analysis

of Dental Alloys

Subtask 4 of Task 12135

J. M. McKinney, R. E. Dehl , W. H. Grant

In vi tro accelerated wear measurements on several dental alloys

have been characteri zed by low initial wear rates followed by higher

131 maasmamam
steady state rates of wear. We have attributed this behavior to the

formation of a passive oxide surface layer, with higher wear resistance

than the bulk material, that is reformed during periods of mechanical

i nactivity.

We have initiated examination of these surface layers by AES.

Following a period to develop familiarity with the instrumentation

(Surface Science Division, Center for Thermodynamics and Molecular

Science) and confidence in the technique, measurements have been made on

an amalgam, on three crown and bridge alloys, and on nickel as a standard.

Preliminary measurements by argon ion sputtering of the surfaces to a depth of 10 nm has indicated distinct changes in composition as a function

of depth into the surface layer. It is planned to generate AES depth

profiles on a number of dental alloys with a goal of correlating surface

layer analysis to the i_n vitro wear and finally to _i_n vi vo durability.

Analysis of wearing surface layers may prove important for long-term

biocompatibility consideration including toxicity, chemical irritation,

sensitization, and ginginal inflammation from plaque.

Porcelain Fused to Base Metal Alloys

Subtask 5 of Task 12135

J. A. Tesk, R. W. Hinman 1

, E. E. Parry 1

, A. Holmes

Research Associate, U. S. Navy

This investigation is designed to develop knowledge of the physical,

mechanical, and chemical properties of porcelain veneering alloys and

their associated bonding porcelains relative to their use in cast crown

and fixed partial dentures; to determine the effects of fabrication

techniques on clinical serviceability of the restoration; to investigate

factors affecting the bonding of porcelain to new dental alloys; and to

determine potential methods for modification of fabrication techniques

which may lead to improved clinical service. The chemical, physical,

and mechanical properties of new, non-precious alloys are so different

from those of the gold alloys that the application of the same fabrication

techniques for porcelain bonding could be expected to be unsuccessful.

This has proven to be the case, and not enough is yet known to render

non-precious metal porcelain restorations as trouble free as gold porcelain

restorations.

It is suspected that a major cause of porcelain metal failure

resides in the residual stress which develops upon cooling of fired

porcelain restorations. To address this problem, a multi tiered approach

has been taken: (a) development of precise knowledge of the thermal

expansion behavior and other mechanical and physical properties of

porcelain and alloys after being subjected to dental laboratory firing

conditions; (b) the fabrication, according to dental laboratory fabrication

procedures, of split ring composites of porcelain (opaque plus body)

veneered to alloys and determination of the accompanying change in gap;

(c) the development of finite element model and elasticity analysis to

examine the residual stress states and accompanying gap changes; and
(d) examination of porcelain and alloy for microstructural characteristics

as well as examination of the microstructure of the porcelain alloy

composite for stress induced (or other) flaws. Ultimately, the data

developed in (a) and (b) will be used in the theoretical program in (c) to

determine the "macroscopic" residual stress states developed in the

split ring. The analyses may further be developed with the knowledge

developed in d), which may involve the superposition of microscopic

stresses on the macroscopic stresses.

Results obtained thus far have shown that significant differences

exist in expansion of porcelains which have received comparable levels

of firing according to manufacturers' instructions. Differences exist

between manufacturers' porcelains, and some develop significantly different

expansions with repeated firing. Large differences in the amount of

residual stress are fired into different porcelains, as indicated by the

amount of stress relief which occurs.

As compatibility depends not only on the stresses set up by differences

in thermal contraction, but on geometrical shape and the thermal (or

other) relief of stress, a split ring was conceived as presenting a reasonably close approximation to a clinical crown while providing a technique to assess the development of residual stress. Experimental

and theoretical results of studies of gap and shape changes indicate

that a previously derived mathematical expression is not sufficient to

describe the complex interactions which exist and that discrepancies

between theoretical and experimental results indicate stress relief at

temperatures lower than T . These effects will be evaluated with refinements

to finite element model and in view of the differences in crystallinity

which have been shown to exist by Raman laser spectroscopic observations

of the porcelains.

Dental Casting Alloys

Subtask 6 of Task 12135

J. A. Tesk, R. M. Waterstrat 1

, R. W. Hinman2

, E. E. Parry2

Research Associate, American Dental Association

2 Research Associate, U. S. Navy

The commercial alloys now available for dental castings contain

significant amounts of gold, silver, palladium, cobalt, nickel, and

chromium. These metals formerly were abundantly available, but in

recent years there have been sharp fluctuations in the price of these

materials. It appears that the market for these metals will continue to

be increasingly unstable, since there are no viable domestic sources of

the ores, and the United States must import these metals from foreign

countries which are susceptible to political or economic upheavals. The

cost of these alloys is an important factor in dentistry; and in order

to avoid future problems, it is prudent to plan some strategies to meet

unexpected shortages or sharp increases in price. This can be accomplished

by developing alternate alloys, and particularly those whose ores are available domestically. Titanium is an example of one such alternate.

183
We have demonstrated that it is possible to produce precision dental

castings based on titanium, but it is necessary to define the basic

properties of these alloys before any laboratory castings can be produced

for clinical use. During the past year, biocompatibility studies were

completed on a titanium-13 percent copper alloy in cooperation with

Dr. Frank Young at the Medical College of South Carolina. The results

indicate that the alloy is very well tolerated in soft tissues. This is an important step toward eventual clinical trials in humans.

The ease with which a molten alloy fills the refractory mold cavity

during the casting process is another problem that has been associated

with the use of non-precious alloys. In an effort to ascertain the

magnitude of this problem, an objective procedure for measuring the

“castabi 1 i ty" of dental alloys was developed as an early phase of this

project and identified in a previous report. Early data resulting from

this test method were plagued by unacceptably high variability. More

recently, a modification of the pattern sprue has been tested, which

results in much improved data. Using this procedural modification,

extensive study has been undertaken to illustrate the differences in

castabi lity for various alloys when following the manufacturer's casting

instructions. This work suggests that some non-precious alloys are relatively easy to manage in the laboratory. Early subjective clinical

laboratory results appear to correlate quite well with measured values

gathered in this project. The development of an objective technique to assess the correlation with margins on clinical crowns is desirable and

will be pursued.

Dental Ceramics

Subtask 7 of Task 12135

C. P. Mabie 1

, D. L. Menis 1, R. L. Trout 1

Research Associate, American Dental Association

Work continues on the formulation of lower fusing dental porcelain

frits prepared by the gel route. Frits have been made by the gel route

which mature in a 12 minute air fire at 822 °C. These appear suitable

for metal ceramic applications and have a thermal expansion greater than

12 x 10 6 /°C between 23 and 400 °C. A high expansion rate is desirable

to match those of some metals. The fusion or maturation temperature is

125 °C lower than the current lowest fusing commercial metal ceramic

porcelain. Solubility of the low fusing porcelain is in the range of

current commercial products. Deformation temperature under applied load

is about 650 °C, the same as many other metal ceramic body porcelains.

Other porcelain frits have been formulated which fuse at lower_than

900 °C. Some of these have thermal expansions greater than 14 x 10 S /°C

when measured between 23 and 400 °C. Solubilities tend to be high, but

they are still within the commercial range. Many of these have very low

deformation temperatures , i.e., the lowest temperature where stress

between metal and ceramic may be relieved. Work continues on lowering

the solubilities of these porcelains.

184
At least two dental companies have decided to experiment with gel

route prepared frits. The gel route has potential for facilitating the

introduction of nonradioactive phosphors to replace uranium in teeth.

Irradiation Effects From Neutron Activated Dental Materials

Subtask 8 of Task 12135

J. A. Tesk

A potential source of radiation exposure which has not received

direct attention involves secondary radiation from dental restorations

activated by primary exposure to neutrons. This could present an additional

hazard for the civilian and military personnel surviving exposure to a neutron bomb, for reactor operators and experimentalists suffering

accidental exposure, for cancer patients receiving intense localized

neutron radiation therapy, and others occupationally exposed to neutron

radiation. Accordingly, calculations were made to estimate the additional

dose of radiation (p + y) delivered to local oral tissues by neutron

activated gold crowns. A primary 50 REM exposure was used as the baseline

neutron exposure, as this clearly appears to be a complete survival dose

for whole body exposure. For calculation purposes, a single gold crown

of 2 grams was simulated by a disc 0.5 cm in radius and 0.14 cm thick

located entirely on the buccal or lingual sides of a tooth to provide

close approximation to soft tissue. We have concluded that secondary

radiation doses from gold crowns activated by sublethal neutron fluences

are comparable to the original dose from the neutrons. Results indicate

that a 50 REM neutron dose would subsequently be accompanied by ~ 30 REM.

Higher primary neutron doses are followed by higher secondary doses (a

high survival, whole body neutron dose of 200 REM is followed by ^ 120 REM).

Dental or implant materials with major constituents behaving similarly

to gold nuclei and irradiated by neutrons during cancer therapy will

generate secondary doses comparable to the primary and must be duly

considered. Long-range effects of partial irradiation of an organ are

not well known. For the levels presented, concern appears warranted for

minimizing exposure. This research has been summarized in an article to

be submitted to Medical Physics.

Clinical and Laboratory Investigation of Dental Amalgams

Subtask 9 of Task 12135

N. W. Rupp 1

, G. C. Paffenbarger 1

, R. M. Waterstrat 1, R. Busby 1

Research Associate, American Dental Association

The reason for the progressive deterioration of amalgam restorations

is a subject of intense interest although the theoretical understanding

of this behavior is not well developed. Creep and corrosion are generally

recognized as being important factors, but there is considerable controversy

about the relative importance of these two factors, and it is possible

that other significant factors have been overlooked.
Amalgam is a composite mixture of about six major constituents or “phases." The chemical and physical properties of such a mixture will

depend on the properties of the individual phases, the percentage of

each phase in the mixture, the size and shape of the crystals, and the

properties of the interfaces between each phase. Thus, it is important

to study the microstructures of each phase and to identify the tendencies

for a chemical element to occur preferentially in certain regions of the

microstructure. Elements such as tin, copper, manganese, and zinc are known to exhibit such behavior, and they produce important effects on the properties of the amalgam. These effects are being identified in a variety of experimental and commercial amalgams. An effort is then made

to determine the relationships between the observed microstructure and

the clinical behavior of the amalgams.

Currently, we are concentrating on the laboratory phase of the

project. Dimensional changes are being observed for unrestricted specimens

which have been stored in air at various temperatures for over three

years. Seven pairs of alloys (zinc-containing paired with non-zinccontaining alloys of the same brand) have been under observation. All

of the zinc-containing alloys made amalgams that continued to expand for

the three years. The zinc-free amalgams all contracted. When one percent of powdered zinc was added to one of the non-zinc alloys, the

change in dimension increased from -5 pm/cm for the non-zinc to +273 pm/cm.

Thus, it would seem that zinc plays a role in the diffusion of mercury

in hardened amalgam. This new knowledge of the role of zinc in the

alloy may contribute to formula changes which could further improve the

durability of amalgam restorations.

Dental Enamel Chemistry and Preventive Dental Treatments

Subtask 10 of Task 12135

W. E. Brown 1

, L. C. Chow 1, M. Mathew 1, G. L. Vogel 1

, M. Tung 1

, S. Takagi 1

, T. Gregory 1

, H. Heaton 1

, P. Patel 1

Research Associate, American Dental Association

The objective of this project is to develop and apply fundamental

information on the solubility and crystal lographic structure of biolcgicall

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 physicochemical models

of the caries process to include insight into the mechanisms by which

impurities and defects are incorporated into 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.

The structure of the following highly hydrated compounds has been

determined: MgNaP0 4 -9H 2 0 and Ca4 Al Si (S0 4 )F 13 • 1 2H 2 0. These studies on some of the first known examples in which the phosphate ions are completely

surrounded with water molecules provide a new structural basis for

understanding chemical properties of the physiologically important

phosphate ion in aqueous solutions.

186
For clinical application of fluoride in the past we have used a two-step process in which the tooth was first treated with CaHPQ 4 *2H 2 0-

forming solution, and then the CaHP0 4 *2H2 0 was converted to fluorapatite

by a conventional fluoride solution. This procedure was shown to greatly

increase the incorporation of permanently bound fluoride into enamel.

We now have promising data for a new single step procedure which involves

formation of CaHP0 4 *2H2 0 in the enamel. In vitro results showed that

this procedure should be much more acceptable for clinical practice than

a two-step procedure.

The use of relatively frequent mouth rinses with solutions containing

low amounts of fluoride appears to be coming into favor over the use of

infrequent treatments with concentrated solutions. We have made two i

n

vitro studies in which a CaHP0 4 *2H 2 0- forming step is incorporated into

the fluoride rinse procedure. The results from these studies showed

that the permanent fluoride uptake by the enamel was significantly

increased over a method currently used.

A new dental cement system comprising primarily calcium phosphate

has been developed. At present, the cement has a compressive strength

only about one-half that of ZnO cement and requires a setting time of

about 15 minutes. Both the strength and setting time are expected to

improve as the materials and procedures are modified. This cement has

many potential applications in dentistry.

Progress in utilizing ultra-micro techniques to simulate and study

the decay process has been made in several areas. This technique has

produced, for the first time, information on calcium, phosphate, chloride

concentration changes, and the change in pH within enamel when the tooth

specimen is undergoing a carious-like demineralization. This information

provides important new insights into the mechanism of caries formation

and has application to enamel remineralization processes as well.

Adhesion and Surface Coverage of Synthetic Polymers on Solid

Substrates

Subtask 11 of Task 12135

R. E. Dehl , W. H. Grant

Two aspects of the adhesion of polymers to surfaces are of great

importance in their many commercial applications as protective coatings:

namely, (1) the energy of adsorption of individual polymer molecules on the surface, which determines the adhesive strength of the film, and (2)

the extent of surface coverage by the polymer, which determines the

effectiveness of the adherent film in protecting the underlying substrate

from chemical attack. We are presently investigating both aspects of

this important problem by the use of radiolabelled polymers to study the

adherence of the film and by Auger Electron Spectroscopy to study the

uniformity of surface coverage by the polymer.

One measure of the energy of attachment or adhesive strength of

polymers adsorbed on solid surfaces is the rate at which they Qeccme

detached when the polymer-coated substrate is placed in contact with a

187

.yuuuBi.uimMiiiM.ni—iiwmiHnininHnHimuiiunmt
suitable solvent. The desorption rate is affected both by the free

energy of attachment of each segment of the polymer molecule with the

surface and by the number of attached segments per molecule. The results

of previous NBS studies, using radiolabelled polystyrene to detect the

amount 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. Further experiments are in progress

to quantitate these observations by systematically varying the amount of

polymer initially adsorbed, followed by a careful study of the amount

remaining after selected intervals of desorption. In this way, we expect to learn whether the polymer molecules which first arrive at the

surface have a higher adsorption energy than the later arrivals, and

whether such variables as the solvent used to deposit the film and the

time spent in depositing a given amount of polymer on the surface significantly affect the adhesive strength of the film.

Auger Electron Spectroscopy (AES) is a technique for determining

the elemental composition of the topmost 5-10 nm of a solid surface.

The AES probe samples an area of about 20-80 pm2 and can be used to

determine variations in the surface chemical composition, given this

lateral resolution. Preliminary AES experiments indicate that we can detect changes in the average thickness of a polymer film on a metal

substrate as we scan across the sample. We expect to use the AES

technique to study the uniformity of polymer film thickness as it is

affected by the molecular weight of the polymer, the mass of polymer

adsorbed per unit area, the time required to adsorb a given mass of

polymer, and the molecular volume of the polymer molecules in solution

prior to their adsorption. By studying the effect of each of these

variables, we expect to gain insight into the optimum parameters for

applying uniform polymer coatings to solid surfaces.

Characterization of Porosity of Porous Implant Materials

Subtask 12 of Task 12135

R. E. Dehl , W. H. Grant, A. Bur, J. M. Cassel

The use of porous synthetic implant materials to serve as a scaffolding

for the ingrowth of natural hard or soft tissue is a procedure utilized

to stabilize selected medical implants. Characterization of the porosity

of these materials is very important since the porosity governs their

successful utilization. In cooperation with the Bureau of Medical

Devices, Food and Drug Administration, a project has been initiated to

survey published information and current commercial material specifications,

perform void volume measurements on selected polymeric and composite

materials by several alternative methods, and measure pore size distribution

by optical intercept and mercury porosimeter techniques. In addition,

the applicability of an experimental microparticle sieving technique,

heretofore not applied to such systems, will be explored.

The accomplishments of this project's objectives will be of significance to the medical device industry, medical implant standards development,

and ultimately, the users of porous implant materials.

188
Dental and Medical Materials Standards

Subtask 13 of Task 12135

J. M. Cassel , G. M. Brauer, J. A. Tesk, N. W. Rupp 1

^Research Associate, American Dental Association

Active participation, from Task Force level to the role of Subcommittee

Chairman, occurs in development of dental standards through ANSI MD 156,

Dental Materials, Instruments, and Equipment, and ISO TC 106, Dental

Materials and Services. Development of medical implant standards is

assisted by serving in roles of Polymeric Materials Chairman and Task

Force leadership in the efforts of ASTM F-4, Medical and Surgical Materials

and Devices, and as Chairman, USA TAG ISO TC 150, Surgical Implants.

Investigation of Epitaxy Relationships Between Ca^(P0 4 )^0H and

Other Calcium Ortho-Phosphates

Subtask 14 of Task 12135

B. Dickens, L. W. Schroeder1

1 Guest worker, Food and Drug Administration

The purpose of this investigation was to examine possible epitaxies

between Ca 5 (P0 4 ) 3 0H (hydroxyapatite) and other calcium ortho-phosphates.

These epitactical relationships are of interest for the following reasons:

(i) Ca5 (P0 4 ) 3 0H may be considered as an idealization of the major inorganic

phase in the human body, and its crystal chemistry obviously influences

the properties of hard tissues, and (ii) epitactical relationships have

been suggested to be important in explaining the apparent nonstoichiometry

of Ca 5 (P0 4 ) 3 0H and in the growth of biomineral j_n vivo .

Similarity in chemical content and periodicity of the chemical

pattern between two planes in the component structures is an important

requirement for epitaxy to occur under mildly forcing conditions. From

the purely metric point of view, periodicity may be treated in terms of

matching nets, one in each of the two components. In general, the

metric fit of such nets will not be perfect, and the resultant misfit

will be accomodated by lattice strain near the epitactical layer and/or

by dislocations.

For the chemical aspects of epitaxy, structural features such as layers and corrugated sheets are prime candidates for the interfaces.

Many structures contain layers in which the intra- layer bonds are strong

and the interlayer bonds are weak. Especially in the case of inorganic

salts, the atomic confi gurations in such layers will be relatively

stable and, hence, can be expected to be found in more than one structure.

The chemical pattern itself should not have a large motif, because this

would have many structural details, and the probability of finding a similar motif in another compound would necessarily be low. From the

above considerations, it follows that the most likely candidates for

epi taxy-formi ng layers will be planes of low Miller indices of the form

(100), (110), or (210), etc.

139

unu

n
A filtering procedure for generating and quantitatively comparing

possible cases of epitaxy and twinning in ionic compounds has been

devised to provide quantitative criteria to evaluate the probability of

epitaxy between compounds for which the crystal structures are known.

The two cornerstones of this procedure are:

(i) Generate and examine in a systematic , quick manner all possible

cases of epitaxy and twinning that may occur.

(ii) Establish a relative probability of occurrence among the

possible cases to delineate those requiring further study.

Our approach is completely general in that it can be applied to any

substance that forms a crystalline phase. Generation of possible cases

of epitaxy or twinning which are specified in terms of contact planes

requires only unit cell dimensions. Further evaluation of these cases

in terms of atomic correspondences requires atomic positions. The

procedure was used to evaluate the possibility of epitaxy between

Ca 5 (P0 4 ) 30 H and other calcium orthophosphates. For any two given lattices,

pairs of nets which match dimensionally within prescribed limits are found and sorted in order of increasing mismatch. The crystal structural

parameters are used to generate and match atomic patterns corresponding

to each pair of nets. Pattern matching is done by comparing magnitudes

of vectors describing the immediate environment of representative atoms

in the two patterns. Atomic charges related by each vector are also

considered. Use of the vector sets introduces the limitation that

twinning involving reorientation in a contact plane cannot be distinguished

from no reorientation. The procedure is general in nature and has been

applied to the study of possible epitaxies between Ca 5 (P0 4 ) 3 0H and

Ca 8 H 2 (P0 4 ) 6 *5H2 Q, Ca 4 0(P0 4 ) 2 , CaHP0 4 , CaHP0 4 -2H 2 0, Ca(H2 P0 4 ) 2 -H 2 0

p-Ca3 (P0 4 ) 2 , and Ca 5 (P0 4 ) 2 Si0 4.

The highest probabilities for epitaxy are between Ca 5 (P0 4 ) 3 0H and

Ca 8 (P0 4 ) 6 *5H2 0 , Ca 5 (P0 4 ) 3 0H and Ca4 0(P0 4 ) 2 , and Ca 5 (P0 4 ) 3 0H and

Ca 5 (P0 4 ) 2 Si0 4

. Of these, the first is the most likely and is probably

unavoidable under conditions where Ca 8 H 2 (P0 4 ) 6 *5H 2 0 is stable, and the last

is the least likely. Possible epitaxies between Ca 5 (P0 4 ) 3 0H and CaHP0 4 or p-Ca3 (P0 4 ) 2 are less likely than epitaxy between Ca 5 (P0 4 ) 3 0H and

Ca 4 0(P04 ) 2.

Although CaHP0 4 -2H 2 0 and Ca(H2 P0 4 ) 2 -H 2 0 had been suggested to be

important in tooth mineralization, evaluation of the probability of

epitaxy in these cases suggests that any deposition of these phases on one another forms incoherent films which then mechanically block access

of the surrounding solution to the interior and that epi tactical growth

is not important. Therefore, among those cases considered, only the

epitaxies Ca 5 (P0 4 ) 3 0H/Ca8 H 2 (P0 4 ) 6

• 5H 2 0 and Ca 5 (P0 4 )0H/Ca4 0(P0 4 ) 2 appear

likely to occur in practice.

190
Development of Improved Field Dental Composite Restorative Materials

for Military Dentistry

Subtask 15 of Task 12135

G. M. Brauer, N. Rupp 1

, K. Dermann2, J. Stansbury, J. Cassel

Research Associate, American Dental Association

2 Guest worker, Free University of Berlin

Current thrust of this continuing project is to provide guidelines

to the Army regarding materials and techniques for addressing the problem

of poor marginal adaptation that frequently occurs with composite restorative

materials. Resultant marginal staining and leakage compromises the

aesthetic advantages of these restorations and can reduce their service

life.

The role of polymerization shrinkage, coefficient of thermal expansion,

nature of filler, and properties of diluent monomers are being investigated.

Efforts are being made to establish optimum minimum levels of viscositymodifying diluent monomers that will produce adequate working characteristics

and physical properties, while at the same time reducing the polymerization

shrinkage that occurs on hardening. Radiotracer techniques are employed

to ascertain leakage around class V restorations placed in extracted

caries-free teeth.

191

MECHANICAL DURABILITY OF PLASTICS FOR DESIGN AND USE

Task 12136

Current trends are to use polymeric materials in applications where

long-term mechanical reliability is critically important. Examples in areas of national concern include the increasing use of plastics and

composites in transportation, in energy production, storage and distribution,

and in medical implant devices. The lack of adequate test methods and

data for evaluating long-term mechanical performance not only restricts

applications, but also leads to overdesign which results in more expensive

items and limits potential weight savings. 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. A joint program with the National

Heart, Lung, and Blood Institute is aimed at developing accelerated test

methodologies for evaluation of candidate biocompatible elastomers for

use as bladders in circulatory assist devices. The Bureau of Medical

Devices of the Food and Drug Administration supports an investigation of

the relationships between the fine structure morphology of ultra high

molecular weight polyethylene and the long-term mechanical properties of

this material when used in medical implant devices. The mechanical

performance of elastomeric seals in geothermal energy wells is of concern

to the Department of Energy, and a joint effort is aimed at developing

tests to estimate accurately the long-time behavior of seals in any

condition of interest. In all of the above applications, there exists a need for test methods and standards to ascertain the physical limits of

polymeric materials in various use environments. An outgrowth of a recent project with the Department of Transportation on the mechanical

durability of plastic shipping containers has been the development of a new test for environmental stress cracking. This test has been reported

to ASTM for evaluation as an improved standard method for stress-crack

resi stance.

Evaluation and control of materials parameters which affect long-term

performance should lead to more durable materials and, hence, reliable

performance for the intended service life. Task objectives are to

identify and analyze principal failure mechanisms in polyethylene and

elastomers under mechanical stress in the use environment. An integral

part of these objectives is to determine the effects of chemical structure

and mechanisms and fine structure morphology on mechanical properties.

Activities in nuclear magnetic resonance, vibrational spectroscopy

,

electron and optical microscopy, as well as x-ray diffraction, are directed toward elucidating these effects.

Mechanical Durability of Polyethylene

Subtask 1 of Task 12136

J. M. Crissman, L. J. Zapas , G. M. Martin

In previous work done for the U.S. Department of Transportati on

,

Office of Hazardous Materials Research, a failure mechanism was identified

which is highly sensitive to the presence of a stress-cracking agent.

193
This mechanism is associated with the region of small deformations. In an effort to obtain a better understanding of this mechanism, experiments

have been carried out on prestretched specimens. In the case of equal

biaxial deformations under inflation, the interesting result is that

this mechanism is highly influenced by the magnitude of the prestretch

history and in such a way that the material becomes more stress-crack

resistant. For example, a tenfold increase in lifetime was observed for

specimens which were prestretched in air by twenty- five percent, were

then left to relax, and subsequently were reloaded in the presence of

stress-cracki ng agent. The eventual failure occurred at strains of

twelve percent or less. After prestretching, the permanent set in the

specimen was of the order of five percent or less. In all cases where

the amount of prestretch was higher than the strain at failure, a significant

increase in lifetime was observed. Further investigation is needed in

order to understand this interesting behavior. In the case of uniaxial

strain histories, the results of similar experiments were inconclusive.

In other work related to mechanical durability studies, we have

shown that the phenomenon of neck formation, which occurs for uniaxial

deformation histories, can be described by a mechanism leading to instability.

Two different theoretical models (phenomenological) have been derived

which lead to such an instability. To test the validity of either

model, we have chosen for study two types of linear polyethylene having

widely different molecular weights. One sample, having a molecular

weight (Mw) of 192,000, exhibits necking at room temperature. The other

polymer, an ultra high molecular weight material (Mw > 2 x 10 6

) does not

show necking at room temperature, but extends homogeneously until fracture

occurs. In both theories one should be able to predict from single step

stress-relaxation experiments, carried out at different levels of strain

in uniaxial extension, whether or not an instability occurs. Measurements

made at very small deformations indicate that the behavior of the two

polyethyl enes is very similar. However, at deformations above eight

percent, deviations in behavior occur which are consistent with both

theories. Data have also been obtained for specimens of highly crosslinked polyethylene which have a density very close to that of the ultra

high molecular weight linear polyethylene. The cross-linked material

does show the phenomenon of necking. Therefore, experiments other than

mechanical will be required in order to elucidate the differences between

the two polymers and may lead to a better understanding of the phenomenon

of neck formation from the molecular point of view. We know from previous

experience that the incipient point of instability for linear polyethyl enes occurs about a factor of two in time earlier than the time for which the

neck becomes visible. One of the continuum theories predicts that the

incipient point of instability will occur when the instantaneous jump

modulus goes to zero. If the model is valid, then it should be possible

to devise tests for nondestructive evaluation.

Stress-Cracki nq Test for ASTM

Subtask 2 of Task 12136

J. M. Crissman, L. J. Zapas, G. M. Martin

This project concerns the development of an improved test method

for the determination of the stress-crack resistance of ethylene plastics.

•wMwmaanMi immw

mmm 194
Upon its completion, a description of the test method, as well as the

appropriate statistical data will be submitted to ASTM Committee D-20.10

for their consideration. A preliminary report on the test method was presented to the ASTM Committee D-20.10 at their February meeting in

San Diego, California. The test involves the use of a bent strip geometry,

but differs from the current ASTM bent strip test in two important ways:

the specimen is subjected to a constant applied stress and in the region

of the bend, all specimens are maintained in the same geometry.

The failure time can be controlled to some extent by changing one

or more of four parameters: the specimen thickness, the magnitude of

the applied stress, the diameter of a metal cylinder (which determines

the severity of the bend), and the temperature. In order to optimize

these parameters, we are currently in the process of examining three

different types of polyethylene which have widely different stress-crack

behavior. Specimens of each polymer are being tested at two stress

levels, two different cylinder radii, two different thicknesses, and at

two or more temperatures. To determine the repeatability of the measurements,

ten or more specimens are being tested for each set of parameters.

Preliminary results indicate that two advantages of this test over the

current ASTM bent strip test are improved repeatability and shortened

testing time.

Ductile and Brittle Behavior of Polyethylene

Subtask 3 of Task 12136

A. Peter! in

Creep experiments on isotropic linear polyethyl enes by Crissman and

Zapas have shown that failure occurs by brittle fracture at both very

small and very large loads. At intermediate loads, the materials are ductile and after necking may deform to a very large draw ratio before

they break at a substantially higher tensile stress.

The lifetime, t^, at both very small and very large loads may be

described as a sum of the microcrack nucleation time, t , and the microcrack ’ n

’ growth time, t^, in the brittle range and the shear band growth time,

t , after which the sample necks and deforms drastically. It turns out

that the nucleus of the microcrack formed under the tensile load may

produce a craze perpendicul ar to the local stress and a shear band at

about 45 °C to this stress. The craze growth time is an exponential

function of the negative stress, while the shear band formation time is

proportional to the inverse stress. If the curves representing the

lifetimes of the two deformation modes as a function of the applied

stress intersect, then the intersections separate the brittle from the

ductile regime of the sample under tensile load. As a rule, with increasing

temperature the shear band formation curve moves more rapidly to lower

lifetimes than the microcrack growth curve. This expands the ductile

region at the expense of the brittle region. A decreasing temperature

acts in the opposite direction so that eventually the two curves ao noz intersect at all, and the material becomes brittle in the whole lead

regi on.
In this consideration, one has completely neglected the highest

load range where the deformation is so rapid that the material becomes

substantially heated by the deformation work, and hence, tends to fail

like a liquid.

Spectroscopic Investigation of Failure Mechanisms in Polyethylene

Subtask 4 of Task 12136

B. M. Fanconi , J. P. Colson, K. L. DeVries

University of Utah

The spectroscopic techniques of electron spin resonance and infrared

spectroscopy are used to elucidate molecular mechanisms in polyethylene

associated with exposure to y-irradiation and with mechanical deformation

and fracture. The irradiation studies, which have now been completed,

not only gave information on the relationships between the number of new chemical species formed and the level of irradiation, but also provided

a means of evaluating our experimental methods on samples in which the

polymer molecules were not oriented during the exposure process.

Knowledge of molecular mechanisms associated with deformation and

fracture in polymers is the main objective of the present work. Such

information provides the basis' for predicting long term performance from

short time tests as well as insights into how the molecular composition

may be changed to improve performance.

Summary of Result on Irradiated Polyethylene : Measurements of the

concentrations of free radicals by electron spin resonance and of new chemical species by Fourier transform infrared (FTIR) were carried out

on polyethylene specimens exposed to y-irradiation at dosages from three

to fifty Mrads, both in the presence and absence of oxygen. The improved

si gnal -to-noise capability of the FTIR method permitted a direct comparison

of the free radical concentration and the resultant concentration of new chemical groups. It was found that approximately ten carbonyl groups

and two carbon-carbon double bonds were formed per free radical. These

results are comparable with previous estimates and form the basis for an investigation of chemical species formed during mechanical deformation

and fracture.

Chemical Changes Accompanying Mechanical Deformation and Fracture : The molecular mechanisms associated with mechanical deformation and

fracture in polyethylene are elucidated through comparisons between FTIR

spectra of undeformed and fractured specimens. Small variations in the

concentrations of carbon-carbon double bonds, methyl groups, and carbonyl

groups result from rupture of carbon-carbon backbone bonds and subsequent

free radical reactions. These concentrations can be detected in difference

spectra obtained through subtraction of the digital FTIR data. The

ability to detect small concentration variations is enhanced by the

superior sensitivity of the FTIR method over conventional dispersive

infrared spectroscopy. The number and type of chemical groups formed

are correlated with ESR measurements of the number of secondary radicals

accompanying mechanical deformation and fracture.

196

0
Our results can be divided into two regimes associated with the

rate of mechanical deformation. In one set of experiments, the polyethylene

specimens in the shape of dumbbells were rapidly pulled in a tensile

tester until ruptured, while in the other set specimens were allowed to

deform under dead load conditions. In both cases, the deformed or fractured specimens were subsequently heated and pressed into thin

sheets suitable for infrared analysis. In this manner, the difficulties

inherent in comparing spectra of unoriented (undrawn) and oriented

polyethylene which had plagued previous infrared studies of deformed and

fractured polymers have been circumvented.

For the rapidly deformed specimens, we observed that the number of

ketone groups decreases when compared to the reference polymer. This

result is contrary to previous findings and suggests that bond rupture

occurs preferentially near the ketone group and that subsequent reactions

produce low molecular weight ketones which are volatilized during preparation

of the specimens for infrared studies. Assuming that the ketone groups

are preferentially located in the inter! amellar regions, our findings

support the notion that fracture occurs at lamellar interfaces.

When polyethylene specimens are slowly deformed, we observe the

number of carbonyl and vinyl groups to increase, which is consistent

with previously published reports. Experiments are in progress to

substantiate these results on drawn polyethyl enes to determine whether a relationship exists between the level of deformation and the concentration

of each group.

Fracture Mechanics of Polymers

Subtask 5 of Task 12136

E. Passaglia

In April of this year, a new project on the fracture mechanics of

polymers was begun. A complete review of the literature, concentrating

on the effects of plasticity and viscoelasticity, is well along. A

review paper in these areas is contemplated.

Technical work has concerned itself with the viscoelastic nature of

the craze material at the tip of a slowly moving crack. Published

results by Ward and his co-workers [1,2,3] and by Weidmann and Doll [4]

show that the shape of the crazed region is quite accurately represented

by the Dugdale model [5], which was developed for plastic yielding in

metals. In this model, the stress in the yielded zone (which corresponds

to the crazed region) is a constant and equal to the yield stress, with

the length of the zone increasing as the applied stress intensity factor

is increased. In the polymer case, however, it has been shown [4] that

the stress in the crazed region is proportional to the applied stress

intensity, with the length of the crazed region remaining constant.

Moreover, other experiments [6,7] indicate that the craze material is

viscoelastic and not plastic. We, therefore, have the unusual result of

a theory developed for an elastic-plastic material accounting well for

observations on a viscoelastic material.

197

mill'ill
This can, in principle, be explained if the relaxation of stress in

the craze in the growing crack is compensated for by the elongation

provided as the crack grows, in just such a manner as to produce a constant stress within the craze. Since the shape of the craze region

is known from these results, it is, in principle, possible to determine

the relaxation function for the craze material. For the linear viscoelastic

case (which is probably too simple for this situation), this determination

involves calculating the Laplace transform of the crack displacement,

calculating from this the Laplace transform of the relaxation function,

and then inverting this transform. The last step is known to be a delicate mathematical operation, so that while mathematical difficulties

have been encountered, preliminary results show that the method is

feasible.

References:

[1] A. R. Brown and I. M. Ward, Polymer, 14, 469 (1973).

[2] G. P. Morgan and I. M. Ward, Polymer, 1_8, 87 (1977).

[3] G. L. Pitman and I. M. Ward, Polymer, 20, 895 (1979).

[4] G. W. Weidmann and W. Doll, Non-Crystalline Solids, 606 (1977).

[5] D. S. Dugdale, J. Mech. Phys. Solids, 8, 100 (I960).

[6] D. Hull and J. Hoare, Phil. Mag., 26, 443 (1972).

[7] R. P. Kambour and R. W. Kopp, J. Poly. Sci., Ser. A2, 7, 183 (1969).

Physical Testing of Polymers for Use in Circulatory Assist Devices

Subtask 6 of Task 12136 ~ —

R. W. Penn, G. B. McKenna, F. A. Khoury, G. W. Bullman

This project is directed to the development of accelerated physical

testing procedures and to the evaluation of candidate elastomers for use

in circulatory assist devices. The project is supported by the National

Heart, Lung, and Blood Institute of the National Institutes of Health

under contract #Y01 -HV-8-0003. Three candidate materials are under

study along with a standard butyl rubber. The three candidate materials

are a polyolefin rubber, a urethane-silicone copolymer, and a segmented

polyurethane elastomer. During this year, all of these materials have

become, or are becoming, available in adequate supply.

We have obtained results from both uniaxial and biaxial testing

with both static and dynamic stress histories. Our results show that in

static uniaxial loading the butyl rubber is superior to the polyolefin

at short times (high stresses) but that this behavior reverses at long

times (low stresses). Under dynamic (fatigue) loading, the failure

times decrease with increasing test frequency but not rapidly enough to

say that the samples fail after a constant number of cycles. Statistical

analysis of the failure data shows that there is greater variability in

the failure times for the polyolefin rubber than for the butyl rubber in

all tests in which a comparison can be made.

133
Biaxial fatigue test results show that the urethane-silicone copolymer

lasts longer than the polyolefin rubber, which lasts longer than the

butyl rubber when they are compared at the same reduced pressures. For

both the polyolefin rubber and the butyl rubber, the dependence of

lifetime on stress is the same in static and fatigue loading. The butyl

rubber in both cases shows a higher stress dependence. In the case of

both rubbers, the variability in the failure times is greater in static

testing than in dynamic testing. Data for the butyl rubber and preliminary

results for the urethane silicone copolymer from biaxial fatigue tests

at 23 and 37 °C reflect activation energies for the failure process of

22 kcal and 25 kcal , respectively.

Creep data under uniaxial loading have been obtained for all four

elastomers. Creep rates range from 1.7 percent per decade of time for

the segmented polyurethane elastomer to four percent per decade for the

polyolefin rubber.

Examination of the urethane-silicone copolymer by optical microscopy

shows heterogeneities on a coarser scale than has been previously reported.

These structures consist of flattened spheroids with their short axes perpendicular to the plane of the sheet. Their sizes parallel to the

plane of the sheet vary from a few micrometers up to about 30 pm.

Response of Carbon Black Filled Rubber to Cyclic Loading

Subtask 7 of Task 12136

G. B. McKenna, L. J. Zapas

We have been examining the deformation behavior of a carbon black

filled butyl rubber in view of the Bernstein-Kearsl ey-Zapas (BKZ) constitutive equation. Failure behavior has been studied within the context

of cyclic creep and a cycle shifted failure envelope.

For materials which follow BKZ type behavior, the single step

stress relaxation response is a lower bound on the cyclic stress relaxation

behavior, and the single step creep response is an upper bound on the

deformations obtained in cyclic creep. In the responses observed for

the carbon black filled rubber, we found that upon cycling the material,

the creep and stress relaxation responses were outside these bounds.

(See, for example, figure 1). We also found that the softening was more

emphatic in cyclic creep than in cyclic stress relaxation. Further work

needs to be done in order to understand these results for materials

which are nearly elastic in constant stress or strain histories. We

have also found that the material creep response in constant load experiments

is stiffer than that predicted from the BKZ constitutive equation. It

is suggested that an adequate description of the material behavior might

be obtained by developing a theory similar to the BKZ theory which

includes competing effects of stiffening in creep and softening under

load-unload cycling.

In studying the cyclic creep behavior of the butyl rubber, we found

that the creep rate is dependent upon the waveform and frequency of the

test. Also, unlike the case of static creep, the creep rate under the
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200 IHBHB
cyclic loading is a function of the stress level. An interesting point

which arises in examining the cyclic creep data is that the square

waveform load-unload cycle which had a test frequency of 0.02 Hz showed

nearly the same behavior as the sinusoidal load-unload cycle at 0.01 Hz.

This would indicate that stress softening occurs due to cycling but is

independent of the rate of load application. The amount of stress

softening depends upon both time and cycles. This can be seen from the

fact that the amount of stress softening per cycle increases with decreasing

frequency, and the stress softening per unit time increases with increasing

frequency.

The lifetime of carbon black filled rubber in cyclic loading depends

upon the test frequency and the waveform of the loading cycle (e.g. , square wave vs sine wave). We have been able to use cyclic creep data

combined with the notion of a shifted failure envelope to account for

the frequency and wave form dependence of the fatigue lifetime of carbon

black filled butyl rubber.

In simple loading histories, failure of rubbers is readily described

by a failure envelope for which the locus of stress at break vs strain

at break can be represented as a unique curve independent of stress

history. In general, however, the failure envelope can be dependent

upon the loading history. In addition, the amount of change may depend

upon the stress. Since in our cyclic creep experiments we found that

the amount of stress softening was relatively independent of waveform,

and all of our tests were conducted at the same peak stress (5.5 MPa),

we can express the change in the failure envelope due to cyclic loading

by a shift factor a . Then

a

£

bc

aa£

bo ( 1 )

where is the strain at break under cyclic loading, a^ is a shift

factor, which may depend on the level of stress, and £

bo

is the failure

strain (at the same stress) in a simple deformation history (i.e.

,

creep, stress relaxation, constant rate of deformation). With this

assumption, the same shift factor should permit prediction of all of our cyclic failure data by extrapolation of the cyclic creep strain data to

the s bc

determined from eq. (1) and one set of the failure data. The

results are shown in figure 2 in a plot of the predicted number of

cycles to failure vs the observed number of cycles to failure. The

points show the data, and their distance from the dashed line gives the

deviation from the predictions. Given the limited number of data, the

agreement is good. The observed deviations could arise from variability

in the cyclic creep data, a possible history dependence (which we have

ignored) of the amount which the failure envelope shifts, as well as the

normal amount of variability in the number of cycles to failure in

fatigue type testing.

Work is continuing in our study of the effects of cyclic loading on creep and failure of carbon black filled rubbers. An effort is being

made to find an appropriate constitutive law to include the effects of

stiffening in creep and softing due to cycling of these materials.

HUBUH
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202

Observed
Experiments are being conducted to assist in this development. Experimental

work is also continuing to explore in more detail the applicability of

the cycle shifted failure envelope to the description of fatigue lifetime

of filled rubbers.

Relationship Between Morphology and Mechanical Properties of Ultra

High Molecular Weight Polyethylene

Subtask 8 of Task 12136

G. B. McKenna, F. A. Khoury, J. M. Crissman

The starting material used in the manufacture of the polymeric

components of orthopedic prostheses is ultra high molecular weight

polyethylene (UHMWPE) in its nascent state (i.e., as polymerized). The

devices made from UHMWPE are fabricated in one of two ways: a) they are machined from rods or blocks prepared from the raw polymer (usually by

compression molding) or b) they are molded directly from the nascent

polymer powder into the desired shape. In clinical use, the long-term

performance of implants made from UHMWPE is determined by time dependent

phenomena such as creep, fatigue, and wear. The manner in which these

phenomena depend upon the thermal history and resultant morphology is

not well understood.

Under contract with the Food and Drug Administration (FDA) Bureau of

Medical Devices, we are studying the relationship between morphology and

the mechanical properties of UHMWPE. Our work has three specific goals:

(1) To determine the influence of polymer morphology on the time

dependent mechanical properties of UHMWPE and to identify

thereby the fine structural parameters which significantly

affect long-term performance.

(2) To generate data in the areas of compressive creep, stress

relaxation, and time dependent failure behavior which will be

useful as a basis for evaluating the future and current devices

made from UHMWPE.

(3) To devise measurement technigues which will be relevant to the

development of standard test methods for characterizi ng the

time dependent mechanical properties of implants fabricated

from UHMWPE.

During this first year of the project, we have focused our efforts

in three areas: (a) developing the molding capabilities and techniques

to fabricate samples of UHMWPE in a reproducible manner; (b) characterization

of the morphology of the UHMWPE polymer as received after molding and

after deformation and failure; and (c) characterization of the time

dependent mechanical behavior of UHMWPE.

We have developed a technique for fabricating sheets of UHMWPE

using a vacuum mold. These sheets are used for uniaxial and eouibiaxial

test specimens. We are currently developing a technique for fabricating

cylindrical specimens for compression testing.

203
Morphological characteristics of the UHMWPE raw polymer and of the

fabricated sheets are being characterized using scanning electron microscopy,

wide, and small angle x-ray diffraction, optical microscopy, and differential

scanning calorimetry. Initial work has shown that the raw polymer has a grain- like structure which is carried over into the molded sheets.

Also, the melting point of the raw polymer is significantly higher than

that of the molded sheets, which indicates a higher degree of crystallinity

in the raw polymer. X-ray diffraction patterns from samples which have

been drawn to failure and then released show that there is considerable

permanent orientation. Small angle x-ray diffraction shows changes

occurring in the lamellar texture due to the deformation process.

The uniaxial creep and failure behavior of the UHMWPE is being

characterized. Room temperature testing gives the interesting result

that UHMWPE does not neck, but rather deforms and draws homogeneously to

failure. This is unlike the behavior of lower molecular weight polyethylene.

Our test results to date indicate that the time to failure in uniaxial

testing is shorter for continuous loading than it is for zero-tension

cyclic (fatigue) loading at 0.002 Hz. Further testing needs to be

performed to substantiate this result and to determine effects of test

frequency on lifetime.

The Crystallization, Morphology, Deformation, and Orientation of

Polymers

Subtask 9 of Task 12136

F. A. Khoury, L. H. Bolz

Investigations of the morphology of crystalline polymers during the

past year have been mainly in the two areas outlined below.

The Habits of Polyethylene Crystals Grown From Solution at High

Temperatures : The objective of this investigation is to determine the

effects of crystallization temperature, molecular weight, and polymer

concentration on the morphology of chain-folded polyethylene crystals

grown from solution at temperatures which approach and overlap the

temperature range 118-130 °C) in which the polymer crystallizes isothermally in the form of axial ites or spherulites upon cooling from the

molten state.

In an earlier experimental study, polyethylene fractions (molecular

weights 11,400-100,500) and unfractionated ultra high molecular weight

polyethylene (molecular weight ^ 4.5 x 10 6

) were crystallized from

0.01 percent solutions in various solvents in the temperature range 95 to

115 °C. Distinct trends in the effects of molecular weight and undercooling

on the lateral growth habits of the crystals were observed. During the

past year we have attempted to grow crystals from solutions of the same polymer concentration (0.01 percent) at even higher temperatures. This

has been achieved with a fraction of molecular weight 28,900, crystals

of which were grown at temperatures up to 120 °C using docecanol as a solvent.

204
In an attempt to deduce the nature of the conformation (e.g.

,

tent-like or variously curved) of the various species of polyethylene

crystals we have grown between 95 and 120 °C, a study is under way in

which scanning transmission electron microscopy and small -area (diameter

~ 0.4 pm) electron diffraction are being used to determine the details of

the inclination of the chain stems relative to the surface of the lamellae.

Of particular interest in this connection are crystals which, earlier

results indicated, have asymmetric (apparently S-like) cross-sectional

shapes when viewed along the b-axis direction. Our present aim is to

determine how widespread and varied is the manifestation of this feature

among the various types of polyethylene crystals we have grown. We

believe that such cyrstals will serve as useful models for the constituent

twisted lamellae in polyethylene spherulites grown from the melt at high

undercoolings. It has recently been reported in the literature that the

constituent lamellae in such spherulites, which lamellae are oriented

with their b-axis parallel to the spherulite radius, exhibit S-shaped

cross-sections when viewed along that direction [R. H. Olley, A. M. Hodge,

and D. C. Bassett, J. Poly. Sci., Poly. Phys. Ed., 1_7, 627 (1979)].

•)« The Morphology of Compression Molded Ultra High Molecular Weight

Polyethylene : Aspects of the morphology of compression molded ultra

high molecular weight polyethylene (UHMWPE, molecular weight ^ 4.5 x 10 6

),

and the fine structural changes induced in molded sheets of this material

as a result of uniaxial deformation have been examined. This work is

part of a new project which is sponsored by the FDA, and whose objectives

are to characterize the mechanical properties of UHMWPE (G. B. McKenna

and J. M. Crissman) and to examine the relationships between these

properties and the morphology of the polymer. These relationships,

which bear importantly on the durability of products made from UHMWPE,

are of particular interest to the FDA because numerous components of

artificial orthopedic implants (e.g., hip cups, tibia! plateaux) are made from this polymer.

Sheets of UHMWPE which were compression molded at temperatures in

the range 190 to 230 °C and were subsequently cooled slowly to room temperature,

all exhibited a memory of the grain-like character of the as-polymerized

raw polymer powder which is the usual starting material from which the

implant components are manufactured. The density of the sheets was

0.936 gm/cm3. Examination under the optical microscope, with cross

polarizers, of thin cross-sections cut from the sheets revealed a heterogeneous distribution of birefringent structures of varying sizes. In some

regions the sections had a very fine granular appearance. In others,

larger structures were seen, the largest of which were distinctly spherulitic. Small angle x-ray diffraction patterns obtained from the sheets

did not exhibit any distinguishable diffraction ring. This is either

because the thickness of the lamellae was greater than the largest spacing

("- 300 A), which can be resolved in the present instrument, or because

there is a large distribution in the thickness of the lamellae due to

the fact that the polymer was not crystallized i sothermal ly.

Oumbbell shaped samples cut from sheets molded at 200 °C were

subjected to uniaxial extension at 1 mm/mi n at 23 °C, 37 °C, and 70 °C.

In contrast with lower molecular weight linear polyethylene (e.g.,

205
molecular weight < 200,000) the samples deformed uniformly and did not

exhibit any necking even up to the breaking point. Current experiments

are aimed at determining the recovery of samples from deformation at

23 °C, 37 °C, and 70 °C to various strains below the breaking strain.

Low angle and wide angle x-ray diffraction and scanning electron microscopy

are being used in an attempt to determine the nature of the permanent

and recoverable changes in orientation and fine structure resulting from

deformation to various strain levels. Structural changes resulting from

stress relaxation will also be examined.

Polymeric Sealants for Geothermal Energy

Subtask 10 of Task 12136

E. A. Kearsley

The Department of Energy (DOE) envisions that within a matter of decades

the exploitation of geothermal energy resources will be making a substantial

contribution to our national energy needs. However, in order for this

to be accomplished, it is necessary to stimulate several associated

technologies. The Division of Geothermal Energy of DOE has accordingly

requested help in developing tests of polymeric materials to screen

likely candidates for use as geothermal sealants. Since there are many

forms of seals used in the drilling and production of geothermal wells,

and down-hole environments vary considerably among the different well

locations, it is not possible to specify reasonable requirements for

geothermal sealants in general. The most interesting and energetically

important wells are potentially those with ambient down-hole temperatures

greater than 260 °C and with strongly corrosive reducing (rather than

oxidizing) atmospheres. The sealant materials should perform (frequently

this means maintaining large elastic stresses for fixed deformations)

under these demanding conditions for time periods ranging from hours for

well-drilling sealants to months or years for production seals. Current

technology for such seals is largely based on developments for the

petroleum industry and is, consequently, adapted to lower temperatures

and less corrosive conditions.

At present, various ad hoc lifetime tests are used by designers of

geothermal equipment to test specific seals under conditions simulating

the intended use. Such tests are very specialized and inconvenient.

Failures of the seals are observed to occur either because the sealant

hardens and eventually cracks or because the sealant softens and flows.

The program on geothermal sealants in the Polymer Science and Standards

Division aims at a more fundamental test which gets at the causes of

this behavior so that the results can be used to design seals for whatever

configuration or geothermal environment is needed. This is to be achieved

by measuring the rates of formation and of breaking of bonds (cross-links

or equivalent) affecting the elastic properties of sealant materials

aging under controlled conditions. With information on how these rates

depend on the parameters of the down-hole atmosphere, it should be

possible to estimate accurately the long-time behavior of seals of any

geometry (e.g. , packer seals, o-rings, chevron seals, etc.) in any

conditions of interest.

206
The customary way of measuring rates of cross-link breaking and

forming is that developed by Tobolsky et al., to study oxidative degradation

of rubber. In that method, two sets of measurements are required:

(1) the stress relaxation of material aging while deformed and 2) the

change in elastic modulus of material aging in an undeformed configuration.

The latter data can be collected rather routinely, but stress relaxation

is an inconvenient experiment, particularly under conditions corresponding

to geothermal down-well atmospheres. Consequently, we have worked out

the theory of a method to substitute permanent-set data for the stress

relaxation data needed for the Tobolsky method. The theoretical work

for this is completed, but there remains the task of establishing the

most practical experimental methods of making the measurements.

Currently, the technique is being evaluated using simulating temperatures

but not simulated geothermal fluids. The test samples are sealed in

evacuated glass tubes during aging (at 260 °C) to avoid oxidation, since

geothermal atmospheres are normally reducing rather than oxidizing. The

conditions necessary to simulate complete relaxation prior to the measurement

of permanent-set are still not completely known. Concurrently, an apparatus is being constructed to age samples in more realistic conditions,

that is, in water compressed up to pressure of 5000 psi at temperatures

up to 350 °C. Such conditions may induce hydrolysis of the sealant

materials, thus affecting bond stability.

Characterization of Polymeric Solids by 13 C NMR

Subtask 11 of Task 12136

D. L. VanderHart, S. J. Kryder

High resolution 13 C NMR of solid samples has been greatly aided by

the recent development of magic angle sample spinning (MASS) together

with the technique of high-power proton decoupling. With MASS, 13 C NMR

lines in solids appear at their isotropic chemical shift positions, just

as they do in liquids, thereby enabling one to separate resonances

corresponding to chemically different carbons. In the absence of MASS,

13 C lineshapes are much broader, and different 13 C resonances are likely

to show a modest to severe overlap. Nevertheless, these lineshapes in

chemically simple materials, e.g. , polyethylene (PE), contain interesting

orientational information, and as discussed below, we have made use of

such measurements to follow the orientational behavior of noncrystall i ne

PE chains during annealing. For the last two years MASS capability has

also been available on a spectrometer with a magnetic field of 1.4 T. This past year, however, a 4.7 T superconducting-solenoid spectrometer

was installed as an NML facility. This spectrometer, although principally

equipped for liquid-state NMR, also has MASS capability in conjunction

with 13 C NMR in solids, and this facility is expected to become a more

significant instrument for our program because of its higher sensitivity.

Studies of Orientation in the Mon-Crystalline Regions of Drawn

Polymers : It has been demonstrated here that it is possible to separate

io C signals in polyethylene (PE) arising from chains having preferential ly

high mobility relative to crystalline chains. Furthermore, it is possible
to analyze the distribution of orientations. These studies are being

extended to include ultra high molecular weight drawn PE whose macroscopic

drawing characteristics (maximum draw ratio, lack of necking) are quite

distinct from the lower molecular weight samples. Further, if samples

can be obtained, it would be of interest to examine Penni ngs-type solutionshear-aligned PE fibers because the morphology is established by crystallization in shear flow rather than by deformation. Thus, one might expect

more extended chain material but perhaps a reduction of entanglement-related

connectivity. There is current effort to extend this method for measuring

non-crystalline orientation to polyethylene terephthal ate (PET), which

is a commonly used commercial fiber. In PET, preliminary experiments

have shown promise that the CH2 resonance can be used to determine

orientation in the non-crystalline region. But PET is more complicated

than PE in that the ratio of relaxation times (molecular mobilities)

between the crystalline and non-crystalline phases is expected to be

smaller than in PE; furthermore, there is some argument about whether

crystallinity means organized molecular packing or merely all-trans

chains. Further work on these substances will also involve correlations

with mechanical properties as well as the acquisition of a non-spinning

probe for the 4.7 T NML spectrometer to take advantage of its higher

sensitivity. Use of non-spinning 13 C NMR as a comparative tool in

monitoring orientation in glassy polymers below Tg should also be investigated.

Resolution in 13 C MASS Spectra in Polymers : This work is aimed at

evaluating the capabilities of the 13 C MASS technique for (1) studying

relaxation of individual carbon sites, (2) studying tacticity and/or

conformation in the solid state, (3) using the method as an analytical

tool, and (4) using linewidths as a source of information about molecular

motion or molecular packing.

We are currently in the final stages of preparing an extensive

manuscript on the subject of resolution in the 13 C NMR of hydrocarbons

using MASS. One result of this study is that molecular motion in the

mid-kilohertz region produces overwhelming broadening for protonated

carbon resonances. Thus, if one wishes to perform analytical measurements

on a sample and needs best-available resolution, the ability to vary

temperature and move to a region where motions do not create inordinate

broadening is highly desirable. Another outgrowth of looking into the

resolution question is the recognition that solid polymers often exhibit

chemical shift dispersions and discrete magnetic inequivalences which

are unique to the solid and which are averaged in solution. Chemical

shift dispersions can arise from variation in the packing of chains.

This is a difficult problem to address theoretical ly because of the

complex nature of the chemical shift expressions. This problem was addressed experimentally by looking at changes in resonance positions of

the interior methylene resonances in the alkanes as a function of crystal

structure. The n-alkanes are found to have four crystal habits, and

correspond!' ng resonances were found to range over 1.3 ppm. Thus, it was concluded that packing variations, particularly in glassy polymers, can account for chemical shift dispersions of the order of 1-2 ppm and that

no conformational variations need be invoked to explain such dispersions.

This is an important perspective to have gained.

208
With respect to discrete magnetic inequivalencies, consider crystalline

isotactic polystyrene which shows six distinct aromatic carbon resonances,

whereas only four are observed in solution. Variable temperature studies

of the collapse of such inequivalences in the solid would give very

specific information about the frequency and nature of molecular motion,

e.g. , initial collapse from six to four resonances in polystyrene would

correspond to rotation of the ring about the aromatic-aliphatic C-C bond

direction at a frequency closely related to the splitting. Therefore,

one of the badly needed instrumental modifications required is to design

and build a variable-temperature MASS probe. It is not a simple matter

to design such a probe without sacrificing sensitivity. Nevertheless,

it is a high priority item to equip both the high and low field instruments

with such a probe, in order to:

(1) move away from undesirable temperatures to get improved resolution,

(2) study temperature dependent motions in polymers,

(3) improve quantitation (will be discussed) for analytical applications, and

(4) study conformational equilibria.

Quantitation in 13 C NMR Spectra of Solids : If a broad-band pulse

is applied to 13 C spins having equilibrium Boltzmann populations, resulting

NMR spectra are quantitative in the sense that each 13 C nucleus appears

to make an equal contribution to the total signal. Because 13 C signals

are inherently weak and because many carbons have no directly bonded

protons (thereby making their relaxation times long), the method just

described is seldom used to generate 13 C signals. Rather, cross-pol ari zation

techniques are usually used in which 13 C magnetization is transferred

from protons to carbons. While this method generally enhances the 13 C

signals over the first experiment by a factor of 3 to 4, and further,

allows one to repeat scans in a time determined by the proton rather

than slowest carbon relaxation, the quantitativeness of the resulting

spectra is no longer assured. On theoretical grounds, distortions of

true intensities can be expected both when molecular motions are in the

mid-kilohertz range and when molecules are isotropically tumbling and

translating. This general area deserves more attention in polymers,

particularly in blends, copolymers, or multiphase polymers. Such distortions

are observed in the spectra of PE, as well as polycarbonate and polyethylene

oxide. For exploring the problem of quantitation, temperature is an essential variable. A particular area where quantitation problems are likely to be severe is analysis of extent of curing, e.g., in dental

compos i tes.

Impact and Use of the High Field NMR : There is no doubt that

sensitivity per scan is higher at high field, but relaxation times for

slowly moving molecules may increase tenfold with respect to the lower

field, thereby making relative sensitivities comparable. A perspective

must be developed. Resolution using MASS at high versus low field is
still an open question. It is only a rare case where resolution dramatically

improves; nevertheless, a more complete perspective must be developed

here in order to optimize spectral information.

Acoustic Emission of Crazing Polymers

Subtask 12 of Task 12136

A. Peterlin, R. E. Green 1

, B. B. Djordjevic 1

, R. C. Murphy 1

1 Johns Hopkins University

After repeated attempts to observe acoustic emission in strained

poly(methyl methacrylate) (PMMA), we have concluded that the emission

occurs in the millisecond range where the noise background of the stretching

machine completely masks the acoustic emission. Therefore, a statically

bent PMMA specimen was observed with a reflected laser beam during the

wetting of the bent surface by a droplet of benzene. The formation of crazes and vertical displacements of the surface of the bent slab of

PMMA were observed. Indeed, the duration of the pulse, detected by the

vertical motion of the polymer surfaces reflecting the laser beam,

turned out to be in the millisecond range. Time extension of the pulse

has shown a fine structure which is mainly caused by the interference of

the primary signal with the waves reflected at the fixed ends of the

bent slab. The reflections distort the acoustic emission signal to such

an extent that its time dependence cannot be determined.

The optical method has definitively shown that the craze forms

relatively slowly in about 1 ms and that it forms in a great many single

steps of almost equal amplitude. Concurrently, the bent slab assumes a more bent position as a consequence of the elongation of the convex bent

surface by the newly formed craze. Since the new position is obtained

by damped oscillations which displace the reflecting surface of the bent

slab vertically, the laser signal also records this movement which has

no direct connection to the acoustic emission of the craze.

Non-Linear Elastic Behavior of Polymeric Materials

Subtask 13 of Task 12136

E. A. Kearsley, G. B. McKenna, L. J. Zapas

The theory of finite deformations of an elastic medium is often

used with the added restriction of incompressibility of the medium.

This restriction makes possible the solution of several classes of

problems in terms of an unspecified strai n-energy potential; however, it

excludes the possibility that the elastic material properties depend on pressure. To make possible the use of these solutions in cases where

material properties are pressure dependent, we have derived a different

form of the theory. Through a Legendre transformation , the equations of

finite elasticity of a compressible medium were formulated in terms of

an elastic potential whose independent variables are pressure and shear

rather than the usual deformation invariants. This elastic potential

nas no explicit dependence on volume change. Rather, the two derivatives

210
of the potential are equal to the stress deviator and the volume change.

The form of the resulting elasticity equations makes clear the mechanical

effects of introducing a large ratio of bulk modulus to shear modulus

into elasticity theory and leads to a theory of an (almost) incompressible

medium for which the shear modulus depends upon the isotropic part of

the stress. Through the elastic potential, some specific relations

among the pressure coefficients of the mechanical moduli and the change

of volume with deformation can be derived. These relations are accessible

to experiment, and they suggest an interesting method of elucidating the

effects of pressure on the mechanical behavior of natural rubber.

Our recent work with the theory of rubber elasticity has shown that

the strain-energy function for elastomers (which determines the non-linear

elastic behavior) may be measurable from experiments simpler than hitherto

thought possible. However, the method depends upon the strain-energy

relation having a special form (the Val ani s-Landel form). Although some data already in the literature support this requirement, there are also

some published data which raise questions about its validity. The point

needs clarification. Experiments are under way to test the validity of

the Valani s-Landel form through an experiment on simultaneous extension

and torsion of cylinders of elastomers.

Non-Linear Viscoelastic Behavior of Poly(methyl methacrylate)

Subtask 14 of Task 12136

G. B. McKenna, L. J. Zapas

We have conducted single step stress relaxation experiments on cylinders of poly(methyl methacrylate) (PMMA) where we measured torque

and normal force responses as functions of time and angle of twist. By

assuming that torsion is an isochoric motion and that volume effects are separable, we obtained [1] isochronal values for the derivatives of the

strain potential function, 8W/8I! and 3W/8I 2

. Our results showed that

3W/3I-L is negative, while 3W/3I 2 is positive and greater in magnitude

than 3W/3I-L. These findings provided the possibility of explaining the

phenomenon observed by Sternstein and Ho [2] that the single step stress

relaxation responses of PMMA are different in torsion and in simple

extension. Specifically, the time rate of decay of stress is significantly

higher in torsion than in extension. This phenomenon was observed at

small strains where the stress responses in torsion and extension were

linear in the appropriate strain measures.

Using a form of the viscoelastic strain potential function similar

to the Valani s-Landel [3] form of the strain energy function for elastic

materials, we calculated the response in simple extension from our torsion-normal force determined values of 3W/8I! and 8W/8I 2

. Although

we obtained good agreement between our calculated and our observed

extensional behaviors, we could not account fully for the observations

of Sternstein and Ho [2].

Table 1 shows some isochronal data for 3W/3I 1 (t) = W x (t) and

3W/3l 2 (t) = W2 (t) for measurements made on PMMA in the form of both

annealed rod and unconditioned tube. We remark on three things about

211
these data. First, Wx (t) is negative while W2 (t) is positive and of

greater magnitude than Wx (t). This is different from the behavior

usually observed in rubbers and polymer melts, where W x is usually

positive and larger than W2

. Another observation we can make is that

W x (t) and W2 (t) exhibit different time dependences.

Also, the time dependence of the modulus, 2(W 1 +W2 ), is different

from that of either W x (t) or W2 (t). (At the limit of small strains,

i.e. , in the linear range, the modulus G(t) = 2[WX

( t) + W2 (t)]). Finally,

the magnitude of W x (t) + W2 (t) is different for the two different PMMA's.

This is not attributable to the geometry difference but may be due to

the differences in both source and thermal histories of the materials.

Table 1

Some Isochronal Values of Wx (t) + W2 (t), W^t) and W2 (t) for PMMA

Annealed Rod

W i+W2 Wi W2 W : +W2 Wi W2

YR GPa GPa GPa GPa GPa GPa

1.64s 0.00252 0.63 -2.19 2.82 1678s 0.488 -1.94 2.43

0.00946 0.59 -1.98 2.57 0.456 -1.39 1.84

0.0126 0.58 -1.82 2.40 0.442 -1.15 1.60

0.0252 0.53 -1.10 1.63 0.379 -0.616 0.995

Uncondi ti oned Tube

1.64s 0.0095 0.48 -1.24 1.72 1678s 0.36 -0.79 1.15

0.012 0.46 -1.24 1.70 0.35 -0.76 1.11

0.016 0.45 -1.14 1.59 0.33 -0.65 0.98

0.0208 0.44 -0.96 1.40 0.31 -0.47 0.78

From these data we determined isochrones for the viscoelastic

function w

1 (A.) for both the rods and tubes. From the we th

calculated alx (t) - cr 22 (t) for simple extension. The agreement between

the calculations and the experiments was within the uncertainty for our values of w'(\,t). (This uncertainty in the small strain region is

approximately ± 15 percent due to the large uncertainties in the normal

stress measurements in this region.) Of greater interest is the comparison

of the relaxation rates in extension and torsion.

Table 2 summarizes our results and those of Sternstein and Ho [2].

The relaxation rates given in table 2 are calculated from the slopes of

log (stress) vs log (time) plots. There are several things about these

data which need to be discussed. First, Sternstein and Ho obtain

greatly different rates of relaxation in extension and torsion (-0.0195

vs -0.0329) at strains of e = 0.005 and y = 0.01, respectively. Our

data in torsion show a slightly higher relaxation rate than theirs for

Y = 0.01 which increases as y increases. Also, our data indicate that

there is little difference in relaxation rates in extension and torsion

212
at strains less than e = 0.02 and y = 0.04. But at strains of e = 0.02

and y = 0.04 and higher, we find that there is a more rapid torsional

relaxation rate than extensions! relaxation rate (-0.058 vs. -0.047).

We are currently planning experiments to further elucidate these differences

and perhaps account for the differences between our data and those of

Sternstein and Ho.

Table 2

Relaxation Rates for PMMA for Different States of Deformation

Strai n Relaxation Rate 1

Tension Simple

Predicted Observed Torsion 2 Shear3

Data of Sternstein & Ho 1

: s = 0.005; y = 0-01 -0.0195 -0.0329 “ —

Unconditioned Tubes:

e = 0.01; y = 0.02

£ - 0.02; y = 0.04

-0.0397

-0.051

-0.0384

-0.047

-0.0377

-0.0581

-0.0450

-0.0634

Annealed Rods:

£ = 0.005; y = 0.01

£ = 0.0075; y = 0.015

-0.0370

-0.0371

-0.0319

-0.0335

-0.0345

-0.0360

-0.0395

-0.0420

Calculated from the slope of log (stress) vs. log (strain) plots.

Rate is per decade of time.

2 0bserved experimentally, y is the maximum strain in the tube or rod.

Calculated from values of Wx and W2 obtained from torsion-normal

force measurements, y is the shear strain.

References

[1] G. B. McKenna and L. J. Zapas , "Determination of the Time Dependent

Strain Potential Function in Poly(methyl methacrylate)," paper

presented at the 49th Annual Meeting of the Society of Rheology,

Houston, Texas, October 1978.

[2] S. S. Sternstein and T. C. Ho, "Biaxial Stress Relaxation in Glassy

Polymers: Poly(methyl methacrylate)," J. Appl. Phys. , 43, 4370

(1972).

[3] K. C. Valanis and R. F. Landel , "The Strain Energy Function of a Hyperelastic Material in Terms of Extension Ratios," J. Appl.

Phys. , 38, 2997 (1967).
Retractive Forces in Drawn Low Density Polyethylene During Annealing

Subtask 15 of Task 12136

A. Peter! in, R. Russo 1

, F. DeCandia 1

, V. Vittoria1

laboratory for the Technology of Polymers and Rheology, CNR Naples,

Italy

The retractive forces in drawn low density polyethylene depend on temperature and time. At room temperature, the material looks fairly

stable. Above 70 °C, the drawn sample starts to shrink. The shrinkage

forces can be observed on a material with fixed ends. At a given temperature,

they first increase to a maximum and then drop to a relatively high

limiting value. The maximum force and the asymptotic value have a maximum at about 90 °C.

If the sample is heated at a sufficiently slow rate, the restoring

force reaches a maximum at about 90 °C and subsequently drops almost to zero near the melting point of the material. The molecular explanation

of the observed effects is based on the mobilization of taut tie molecules

and on their relaxation at the high temperature of the annealing which

permits a pulling of chain sections from the crystal blocks in which the

taut tie molecules are fixed. During cooling, the restoring forces are substantially lower than during heating as a consequence of the relaxation

of the taut tie molecules by the annealing effect of the previous heating.

Permeation Performance of Polyethylene Used in Containers for

Hazardous Materials Transportation

Subtask 16 of Task 12136

J. C. Phillips

The initial phase of this work involved the development of test

methods for the permeation performance of polyethylene shipping containers

to be used by the Department of Transportation. These experiments

consisted of weight loss determinations for an n-alkane series, n-alcohol

series, and n-carboxyl ic ester series. The loss rate, Q^, results were correlated with an effective carbon atom number, n , for each compound.

Due to limited chain lengths (N^ < 8), the shorter members of the alcohol

and ester series showed deviations from linear behavior of log versus

The final phase of this work was concerned with loss rate measurements

at t = 50 °C for permeants of the n-alcohol and n-carboxyl ic ester

series in which chain lengths were extended to = 16. For the permeants

studied and the polyethylene (PE) bottles used (p ~ 0.92 g/cm3 and

p ~ 0.94 g/cm3), the effective carbon atom number was reasonably correlated

with the loss rate ( i . e . , log Q. versus n was linear and parallel for

each density bottle). 3y using loss rate measurements from the low

— 1 214
density bottle for a group of miscellaneous compounds (1 ,2-dichloroethane,

acetone, methyl ethyl ketone, acetonitrile), the loss rate for the high

density bottle was adequately predicted for these compounds.

This study has verified, at least for the permeants and PE bottles

used, that the effective carbon atom number is a convenient parameter

for transferring the results of permeation measurements among shipping

containers made from various PE resins and, thereby, simplifies the

prediction of transmission performance.

Durability of Paper

Subtask 17 of Task 12136

J. C. Smith, E. E. Toth, E. L. Graminski

Paper used to make currency should have a good balance between

durability and cost, as the replacement of worn out currency is an expensive operation. Because of this, the Bureau of Engraving and

Printing supports work at NBS to identify and characterize those aspects

of the morphology of paper networks which affect durability. The research

results are expected to contribute to the development of durable paper

made from blended wood pulps instead of the more expensive cotton and

linen pulps presently used.

To achieve these objectives, it is necessary to have an improved

understanding of the relationship between the structure of paper, the

morphology of the fibers, the processing conditions, and the mechanical

and physical properties of the paper and its components. Over the past

several years, studies at the National Bureau of Standards on the bondability

of the pulp fibers and on the cellulose-water interaction in rag and

wood pulps have helped to provide some of this background information.

Parameters for characterizing interfiber bond strength can be

obtained from tensile tests on a low density open-web handsheet prepared

from the pulp co be evaluated. The force-elongation curve from a specimen

of this handsheet contains numerous force drops, each drop caused by the

breakage of a bond between fibers constituting the handsheet network.

The relative number of bonds per unit area can be character!’ zed by the

average elongation between bond breaks. The bond strength can be characterized by an average of the force-drop magnitudes, or by an average of

the energy losses resulting from the force drops. The average of the

force levels obtained in a series of tests can also be used to characterize

bond strength. The above parameters, however, are not very precise

because of fluctuations in the uniformity of the test specimens.

Recent work has shown that the force elongation curve of a low

density open-web test specimen has the form

F = A[exp(x/x

c

) - 1],

where F is the force, and x is the elongation. The two parameters, A ana x , are sensitive to the number of fibers per unit area in Lhe

215
specimen tested. Moreover, during a test, A and x

c vary in value as the

test proceeds, reflecting damage to the specimen and changes in the

location of bond breaks. This possibility of characterizing the state

of a specimen at various stages of a test may enable the measurement of

bonding parameters with improved precision. Knowledge of the forceelongation curve parameters will also make possible the comparison of

bonding parameters obtained from tests on samples of different densities.

Morphologies of the handsheets and constituent pulp fibers are being examined by scanning electron microscopy. Results of these investigations suggest that bonding in currency pulps may be due to the presence

of a large fraction of fines which act as a "glue." These fines are not

present in the wood pulps, and bonding between wood fibers depends on the ability of their surfaces to conform and establish intimate contacts

at the junctions.

During the preparation process, pulp is subjected to mechanical

action „such as beating or refining. This treatment causes fibers to

imbibe’water and become more flexible, thereby facilitating interfiber

conformation. However, the microstructure of the prepared pulp is

influenced by the way in which water is bound to the fibers, and this

varies with the kind of pulp material. This is being studied by measuring

the proportions of bound and free water in different pulp samples.

The water imbibed by a pulp specimen is measured by solute exclusion.

A dextran pulp specimen is added to a solution of dextran in water, and

the excess water in the specimen dilutes the solution. The amount of

the dilution is measured by polarimetry, and the imbibed water, or fiber

saturation point, of the specimen is calculated. Part of the imbibed

water is tightly bound to the cellulose and does not freeze at temperatures

down to 223 K. This bound water fraction is measured by differential

scanning calorimetry.

It is found that beating causes increasing amounts of water to be

imbibed by both cotton and wood pulp fibers. However, beating causes an increasing fraction of the water imbibed to be bound in cotton. This

does not happen to as great an extent in wood pulp. It is believed that

free water promotes flexibility and that bound water is attributed to

breakdown of the crystalline structure. Thus, beating of wood pulp

produces flexible conformable wood pulp fibers, but causes fibrillation

and fines formation in cotton fibers.

216
MIGRATION AND THE DURABILITY OF POLYMERS IN USE

Task 12138

Polymeric materials now find their principal markets in construction, appliances, transportation, and electrical systems where long-term

durability is critical to their competitive performance. Reliable

short-term tests are therefore needed for the selection of durable

polymers and knowledge of polymer degradation mechanisms is needed to

guide the development of protective methods and to improve performance.

Technical work this year has emphasized the determination of the mechanism of degradation and stabilization of polyurethanes, the use of

thermogravimetric measurements for lifetime prediction, and the development of chemiluminescence methods for the detection of photoinitiated

oxidation in polymers.

The most general phenomenon related to the durability of polymers

is the effect of protective additives. Almost all commercial plastics

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 increased vulnerability to degradation and failure. This is a major

failure mode of polymers , and programs concerned with polymer durability

must explicitly consider the possiblities of additive migration. A

second consequence of migration is that the migrating substance becomes

a contaminant of the environment or, in the case of plastic packaging

materials, a contaminant of the material being contained. This raises

questions about the toxicological consequences of such migration.

Contamination of food from food packaging materials is regulated by the

Federal Government through the Food and Drug Admi nstrati on , and the

control of migrating substances presents an enormous challenge to the

scientific basis of regulations.

The number of commercially usable polymer-additive combinations is

too large to be considered efficiently on a case by case basis, either

for selection of materials of optimum durability or for regulation of

food and environmental contamination. General material models capable

of predicting migration under a variety of service conditions are needed

to organize polymer-additive combinations into classes for consideration.

The development of these material models is the overall objective of

work done in this task.

Technical activities on additive migration that contribute to this

task include (1) the experimental measurement of additive migration by

several methods, (2) the compilation of critically evaluated data from

this laboratory and the literature, (3) mathematical modeling and empirical

correlation of diffusion data for analysis of data and rapid estimation

of migration, and (4) fundamental theoretical studies of polymer behavior

that can provide truly general predictive models.
Hydrolytic Degradation of Polyester Polyurethane Elastomers

Subtask 1 of Task 12138

^ TM ~ “

D. W. Brown, R. E. Lowry, L. E. Smith

Polyester based polyurethanes degrade in moist air because of the

acid catalyzed hydrolysis of the ester linkages [1]. With soluble

polymers, acid content, A, and number average molecular weight, M, vary

with time, t, according to [2]:

A = A0 e kt

and M” 1 = Mq’ 1 + A0 (e

kt - 1)

Here the subscripts indicate initial values, and k is the fractional

rate of increase in acid content.

These findings were applied to the study of insoluble urethane

foams used in the fuel cells of military aircraft [3]. Foam samples

were aged until soluble. Subsequent agings then enabled us to calculate

k, which permitted prediction of the remaining foam life. A test using

swelling in dimethyl formamide was developed that permits one to judge

very quickly the condition of foam in existing installations.

Polyester polyurethanes are sometimes stabilized against hydrolysis

by the incorporation of carbodi imides [4]. These compounds destroy acid

by the reaction:

( 1 )

We have measured k‘ for reaction of a mono- and of a polycarbodi imide in

polyesterdiol s , in a polyester polyurethane, and in tetrahydrofuran

solutions of a polyester-diol [4]. Except for the reaction of the

polycarbodi imide in the polyurethane, the kinetics of reaction [1] were

second order overall. Values of k' cover a relatively small range

considering the enormous range of bulk viscosities.

Attempts were made to predict the behavior of polyesters undergoing

wet aging using only k and k

1 . The predicted stabilization is much

greater than observed. Reasonably good prediction can be made if a third reaction, one for disappearance of carbodiimide by a zero order

process, is introduced into the mechanism. This reaction could be due

to uncatalyzed hydrolysis or to hydrolysis catalyzed by a material not

reactive with carbodiimide; present evidence favors the latter hypothesis.

If confirmed, better stabilization might be achieved by destroying this

catalyst. Work in this area is continuing.

Polyester polyurethanes containing carbodi imides have been aged for

periods approaching one year at temperatures of 85, 55, and 35 °C at 100

percent relative humidity. Acid content, molecular weight, and carbodiimide

content are all being followed. At 85 °C, lifetimes of polyester polyurethanes

.

, 0

k II -N=C=N- + -C0 2 H -> -N-C-N1

I H 0=0

218
with three weight percent carbodi imide are about threefold longer than

those of unprotected samples. For unknown reasons, the same carbodi imide

content in polyesters gives tenfold greater lifetimes. This study is

also being continued.

References

[1] C. S. Schollenberger and F. D. Stewart, J. El astopl astics , 3, 28

0971).

[2] D. W. Brown, R. E. Lowry, and L. E. Smith, Macromolecules, 13, 248

(1980).

[3] D. W. Brown, R. E. Lowry, and L. E. Smith, "Hydrolytic Degradation

of Polyester Polyurethane Foams," communication to be sent to

Wright Patterson Air Force Base.

[4] D. W. Brown, R. E. Lowry, and L. E. Smith, "Kinetics of the Reaction

Between Polyester Acid and Carbodi imide in Dry Polyester Diols and

in a Polyester Polyurethane," manuscript in review, to be submitted

to Macromolecules.

Thermoqravimetry Studies of Polymer Degradation

Subtask 2 of Task 12138

B. Dickens

Thermogravimetry is important because several of the constant

heating rate and isothermal techniques are easy to apply, because excellent

commercial apparatus is readily available, and because it can be used to

study any condensed phase, soluble or insoluble.

The scientific literature contains many articles on the determination

of the kinetic parameters of polymer degradation using thermogravimetry

,

but there is little or no agreement between the published values of the

parameters. Various estimates differ by as much as 100 percent. Therefore,

we are currently investigating the nature of the rate-determi ni ng weight-loss

process and the use of thermogravimetry to provide realistic estimates

of meaningful kinetic parameters involved in the thermal degradation of

polymers

.

To this end, the technique of factor-jump thermogravimetry was developed in our laboratory and has been used to study the degradation

of several vinyl polymers in vacuum and in nitrogen. The apparatus is

more highly automated and more flexible than commercially available

apparatus. The technique has several distinct advantages:

(1) it is able to determine activation energy using only one sample so that problems arising from differing thermal histories

of two or more samples are avoided,

(2) several activation energies are determined in each experimental

run so that changes in sample behavior can be discerned,

219
(3) because the activation energies are determined from locally

extrapolated rates, no knowledge of the initial and final

sample weights is necessary, and

(4) automatic feedback adjusts the experimental conditions for

changing sample behavior. Points 3 and 4 allow the method to

treat multi-stage degradations successfully.

The results of thermogravi metric experiments conducted on several

polymers under vacuum conditions were fairly erratic and difficult to

interpret. Although it is generally difficult to determine whether the

instability results from the apparatus or the method, it has now been

shown convincingly that a large part of the variation is in the thermal

history of the sample. Only in the cases of polymers degrading with

very long zip lengths to produce mainly monomer could results of chemical

rather than physical significance be obtained in vacuum. The most

fiducial results for all polymers studied so far have been in slowly

flowing N 2 , but even there the experimental conditions play a surprisingly

large role. For isotactic polypropylene, the apparent activation energy

for thermal degradation in vacuum was determined to be 61.5 ± 0.8 kcal/mole;

for linear polyethylene it was 65.4 ± 0.5 kcal/mole. In slowly flowing

N 2 , the apparent activation energy is 54 ± 1 kcal/mole for isotactic

polypropylene and 51.5 ± 0.5 kcal/mole for atactic polypropylene. For

linear polyethylene, the value is 61 ± 1 kcal/mole. These values are significantly different from the vacuum values and from most of the

published values. In the case of polypropylene, a reasonably careful

study carried out elsewhere assigns 56 ± 5 kcal/mole to atactic polypropylene

and 51 ±5 kcal/mole to isotactic polypropylene. Those results are 5-10

times more imprecise than the results from factor-jump thermogravimetry.

We will continue to use the factor- jump thermogravimetry technique to

study the effects of experimental conditions, molecular weight, and

branching on the activation energy of thermal degradation of polypropylene,

polyethylene, and several other polymers.

Computer programs have been written to drive the apparatus and to

conduct various statistical tests to provide estimates of the precision

of the results and to reduce as much as is feasible the effect of aberrant

values. These programs and procedures have been documented in a User's

Gui de.

Variable Heating Rate Thermoqravimetry

Subtask 3 of Task 12138

J. H. Flynn

The prediction of the lifetime of a polymer by extrapolation from

weight- loss data requires a thorough analysis of the degradation kinetics

over a wide temperature range. Techniques have been developed in which

entire kinetic spectra are compared among experiments performed at

heating rates from 6 deg/mi n to 9 deg/day. Simple methods of plotting

data from these techniques have been used for diagnosing shifts in

reaction mechanism, uncoupling of competing processes, ana testing the

validity of kinetic models.

990
Weight-loss studies are continuing on polystyrene, poly(methyl

methacrylate), and polyurethanes in vacuum and in atmospheres containing

nitrogen, air, and water vapor. Subtle changes in mechanism have been

exposed for several of these cases under the milder conditions of the

above techniques. It now appears that rapid conventional thermogravimetric

techniques at high temperatures are inappropriate for the prediction of

service lifetime of these polymers.

Chemiluminescence From Oxidizing Polymers

Subtask 4 of Task 12138

R. E. Florin, B. Dickens

Polymers emit light weakly during oxidation. This effect has

aroused recent interest as a means of monitoring oxidative deterioration

of polymers. A widely accepted theory of the effect is that the light

is emitted during the termination step of the oxidation chain reaction.

Although the quantum yield of light emission is estimated to be only one photon per 10 9 terminations, this inefficiency can be overcome by the

technqiue of counting individual photons, which leads to an extremely

sensitive method, potentially capable of detecting oxidation at temperatures

only a little above those of normal service. In contrast, more accelerated

aging methods require a long extrapolation from high test temperatures

to service temperatures, and the mechanism of degradation probably

changes.

The general objective is to obtain a representati ve data base for

correlating chemiluminescence emission rates with overall oxidation

rates for polymers of differing physical and chemical character!' sti cs

.

The appropriate kinetic parameters are the rates of initiation, propagation,

and termination. We have devised a method for measuring one of the

individual rate constants of the process, that of termination. A prototype

photon counting apparatus has been constructed. Ultraviolet light

activates a photoinitiator solute which then attacks the solvent which

may be polymer, rubber, or liquid. The light can be cut off suddenly,

and decay in the oxidation rate followed to give estimates of the rate

constants of the termination reaction. Oxidations initiated thermally,

without irradiation by light, give estimates of the rate of initiation

of polymer oxidation itself, i.e., the rate of transfer from the initiator

to the polymer. This is because under these conditions the polymer

oxidation is a chain reaction operating in the steady state, and the

rate of initiation is equal to the rate of termination.

Evaluation of transfer of radicals from the photo-initiator to the

polymer provides essential information on the dispersion of the initiator

in the polymer and also allows us to study the influence of the "cage

effect" on the initiation process. Evaluation of the termination rate

constant under various conditions allows us to study the influence of

the cage effect on the termination process. One example of the cage

effect is when two radicals, newly produced adjacent to one another by a bond-breaking process, are held in close proximity to each other by the

matrix and react with one another without attacking their environment.
If a radical escapes from the cage, it continues the polymer oxidation

process until it reacts with either another similar radical or an added

radical -trapping molecule. Effects of cages bring severe complications

in the understanding of oxidation and are poorly characterized.

The chemiluminescence will also be used to study initiation by

sensitive groups on the polymer, such as the ROOH groups produced during

oxidation under normal conditions. Other parameters needed to complete

the characterization of the oxidative chain reaction are the kinetic

chain length and the total amount of oxidation. These can, in principle,

be determined with techniques already described in the literature.

However, to achieve sensitivity useful at the low levels of oxidation at

which the chemiluminescence photon counting method gives useful information,

these literature techniques will need further development.

The extreme sensitivity and very low levels of light emission bring

their own problems. Extreme care was necessary to produce a sample

enclosure with a level of luminescence low enough for the sample to be

"seen." There are problems in dissolving enough photoinitiator in

polymers without precipitating it as a second phase. Also, careful

measurements have shown that oxidation phenomena are not as simple as they are usually thought to be.

The procedure described here is now highly automated, the apparatus

being controlled by a laboratory computer. The existence of spikes of

high counts (cause unknown) and of zero or very low counts from occasional

non-opening of the shutters required the writing of a trimmed-mean

estimating program. Other programs provide needed processing of data

and continuously update the level of photoinitiator left in the sample.

Currently, the optimum technique is being developed, and calibrating

runs are being carried out on simple organic compounds for which the

termination rate constants are known. The procedure and programs developed

up to now are being documented in a User's Guide.

Migration of Oligomers and Antioxidants From Polyolefins

Subtask 5 of Task 12138

S. S. Chang, W. J. Pummer, J. R. Maurey, L. E. Smith

During the last two years, a rather thorough experimental investigation

of the kinetic behavior of the migration of oligomers and antioxidants

from polyolefins into food and food-simulating solvents has been carried

out. This program is under the sponsorship from the Food and Drug

Administration (FDA). Extractions of migrants by actual foods are being

carried out by a separate FDA contract at Arthur D. Little, Inc. The

only food used in the program here is the corn oil, for the purpose of

finding some solvents that simulate the extracting action of food oils.

A large number of experimental variables have been investigated.

These variables are (1) polymers-- 1 i near polyethylene, branched polyethylene

and isotactic polypropylene; (2) mi grants--n-C ls H 38 , n-C 32 H 63 , and 3HT
(3) solvents--com oil, tributyrin, trioctanoin, ethanol, ethanol -water

mixtures, water, n-heptane, and n-octadecane; (4) temperature--30 and

60 °C. Furthermore, the initial concentrations of the migrants in the

polymers and the thickness of the sample plaques have also been varied.

Besides the kinetic studies, equilibrium properties such as solubilities

and partition coefficients have also been studied. The migrants_used

are labeled with radioactive 14 C, to yield a detectibi 1 ity of 10 10

g if

needed. The extraction experiments generally require a few weeks to a few months to complete; however, some experiments are completed within a few days, while some may last longer than a year.

There are about two hundred extraction experiments scheduled. Most

of these experiments are now completed. The diffusion coefficients

observed vary from near 10 6 cm2 s

1 to less than 10 15 cm2

s

1

. Some of

the experiments indicate an ideal Fickian behavior, especially for

pre-swollen polymer in one extreme and for non-swelling solvents in the

other extreme. For the intermediate cases, the diffusion coefficient

may increase from an initial value and then level off at a higher value

or may increase drastically, such that the migrant is exhausted before

seeing the leveling off of the diffusion coefficient at a higher value.

From these results, certain generalizations and correlations can be

drawn for the migration of oligomers and antioxidants from polyolefins.

These findings may form a basis for the estimation or prediction of the

diffusion coefficients in situations not mentioned above.

If all other parameters are held constant, then it seems that the

ranking of importance for the parameters on the diffusion coefficient of

migrants from polyolefin is as follows: solvent, temperature, additivetype, polymer type, additive concentration. The first three parameters

are far more important than the remaining two. There are overlapping

cases of the ranking at the extremes of these parameters.

Effect of Solvent : Solvent is the single most important parameter

in the correlation scheme. For moderate solubilities, e.g., above one percent, one may make correlation of the diffusion coefficients only to

the solvents irrespective of other variables such as polymers, additives,

additive concentrations, and temperatures. Figure 1 shows the correlations

of diffusion coefficients in several solvents versus that in ethanol,

while other variables are kept identical. Although by changing solvents

the diffusion coefficients may change by a factor of more than 2000, the

simple correlations indicated in figure 1 can reduce the variation down

to a factor of 3 or less. The two correlations shown are for n-heptane,

and for the combination of corn oil, tributyrin, and trioctanoin.

The diffusion coefficients in corn oil, tributyrin, and trioctanoin

are nearly identical to that in ethanol within a factor of three. The

ratios of diffusion coefficients among the two pure triglycerides and

the corn oil are in general less than 1.5. Therefore, either ethanol,

tributyrin, or trioctanoin can be used to simulate the extractive action

of corn oil in a great variety of conditions involving different additives,

polyolefins, and temperatures.

223
The accelerated action of n-heptane over that of the corn oil or

its equivalents is clearly demonstrated in Figure 1. The diffusion

coefficient is only 10 to 20 times higher in the case of high diffusion

coefficients, such as in the case of highly loaded n-C 18 H 3 3 in branched

polyethylene at 60 °C. However, the disparity increases as the diffusion

coefficient is decreased, as may be seen in other correlations with

temperature, etc. Thus, for the case of extracting higher molecular

weight oligomers, n-C 32 H66 , from linear polyethylene at 30 °C, the

diffusion coefficient in n-heptane is about 1000 times higher than that

in corn oil or its equivalents.

Combining the effects of the accelerating action and the greater

solubility of n-heptane over that of ethanol for polyolefin oligomers,

the extract of the whole polymer by n-heptane contains a large amount of

higher molecular weight oligomers that may be barely present or absent

in the ethanol extract under the same conditions.

When the solubility is low, e.g. , in the cases of using ethanol -water

mixtures or water as solvents, it is difficult to make simple correlations

as a function of solvent without taking other variables, such as polymers,

additives, partition coefficients, and temperatures, into account.

Effect of Temperature : Similarly, diffusion coefficients for

additive migration at 30 °C may be correlated to the diffusion coefficients

at 60 °C by a single relationship to a factor within 5, irrespective of

all other variables. Again, the effect is minimized at higher diffusion

coefficients and increased at lower diffusion coefficients. Better

correlations can be made by separating other variables such as additives

and polymers. The activation energies observed range from 20 kJmol 1 to

200 kJmol 1

.

Effect of Additive : Changing of additives while keeping all other

variables the same also changes the diffusion coefficients drastically.

It is not possible to construct a simple correlation with respect only

to the additives but irrespective of all other variables. Reasonable

correlations may be made for additive-polymer combinations. Even then,

definitive structures in the correlations due to solvent or temperature

are observed.

Effect of Polymer : For all cases studied, the diffusion coefficient

changes, at maximum, by a factor of less than 50 due to the changes from

low crystallinity branched polyethylene to high crystallinity linear

polyethylene and isotactic polypropylene. Fine correlation requires

other variables such as additive ana temperature to be kept constant.

Effect of Additive Concentration : If the additive, such as 3HT, is

insoluble in the polymer or does not act as a plasticizer, no significant

effect on diffusion coefficients due to the change in additive concentrati on has been observed. Changing the concentration of n-C 18 H 38 from one percent to 0.01 or ten percent may produce a change in the diffusion

coefficient by a factor of 40 in the cases studied. Correlations as a function of concentration for a particular additive but irrespective of

other variables are possible.

224
Q Q O
Concl usion : From the above observations, one can make a reasonable

order of magnitude estimate of the diffusion coefficient if any of the

variables such as solvent, temperature, polymer, and additive concentration

is changed, while the estimation of the effect of changing of additives

without specifying other conditions would be rather difficult.

A Critical Compilation of Data on the Diffusion of Additives in

Polymers

Subtask 6 of Task 12138

J. H. Flynn

The compilation of kinetic constants for the diffusion of organic

compounds in polymeric materials will result in a reliable data base

which may be utilized both to evolve theoretical models for diffusion

mechanisms and to establish empirical relationships for the prediction

of the migration of chemicals and additives in polymers used in the food

packaging, chemical container, and transportation industries. With

support from the Office of Standard Reference Data, a comprehensive

collection of kinetic data on the diffusion of organic compounds in

polyolefins has been completed and prepared for publication.

The tables for low density polyethylene, high density polyethylene,

polyisobutylene, polypropylene, hydrogenated polybutadiene, poly(4-methyl

pentene-1), ethylene-propylene copolymers, and self-diffusion of polyolefins

contain over 250 polymer-migrant entries. Diffusion constants at temperatures

from -30 to 190 °C, activation energies and preexponential factors for

the diffusion process and parameters for the concentration dependence of

the diffusion constant are included.

A special feature of this compilation is an extensive section of

annotated references. These include: (1) as complete a characterization

of each polymer and migrant as is possible, (2) a description of the

experimental methods used to determine the diffusion constants, and (3)

the assumptions made, equations utilized, and calculations performed to

obtain the data in the tables. The justification for this lengthy

section is twofold. The large effects of structure and conditioning of

the polymer substrate on the diffusion process require a detailed description

of the characterization and pretreatment of the polymers if the data are

to be compared and their differences interpreted. Secondly, since

diffusion constants are a function of time, concentration, and distance,

a knowledge of the experimental conditions, methods of measurement, and

theoretical models evoked for the calculations are also essential for an understanding of the data.

The tables exhibit

variations in diffusion

mechanical, and solvent

useful correlations may

remarkable consistencies, considering the great

constants which can be brought about by thermal,

action. These consistencies lend hope that

be developed from these data.

226

I
Work has begun on a similar compilation of kinetic data for the

diffusion of organic migrants in polystyrene—a polymer of commercial

and theoretical importance--which in contradistinction to the polyolefins,

is in a physical state below its glass transition temperature at normal

service temperatures where most of the diffusion data on it have been

obtai ned.

Measurement of Migration in Polymers by Inverse Gas Chromatography

Subtask 7 of Task 12138

G. A. Senich

Inverse gas chromatography (IGC) is being evaluated as a method for

studying the thermodynamic and kinetic interactions of volatile compounds

or probes with polymers. The experimental procedure is similar to

conventional gas chromatography with the exception that a solid or molten polymer replaces the usual liquid stationary phase. Low carrier

gas flow rates insure that the probe retention time is sufficiently long

for a steady-state distribution between the vaoor and polymer phases to

be established. The specific retention volume Vg, a measure of the

thermodynamic interaction between the probe and polymer, is then determined

from the total amount of carrier gas necessary to elute the probe from

the column. Experiments with alkanes and well characterized NBS polyethylene

samples have been performed both above and below the polymer melting

temperature. The Vg values determined above the melting temperature

agree with results in the literature derived for similar systems. An

error analysis has been effected to establish the precision which can be

expected for such experiments. Since the amorphous fraction is the sole

contributor to bulk sorption of the probe molecules below the melting

temperature, the accuracy to which the percent crystallinity is known

limits the reliability of determinations in this temperature region.

The polymer-probe interaction parameter has been calculated from Vg by

applying relations derived from the equation of state based polymer

solution theories of Flory and of Sanchez and Lacombe, both yielding

similar results. This parameter can be used to predict a limiting value

of the partition coefficient, which describes the distribution of the

probe between a polymer and a non-swelling liquid in contact with it,

provided that the solubility of the probe in the liquid is known to be

smal 1

.

The migration kinetics of a probe in the polymer phase can be

related to the degree of broadening of the eluted probe pulse over its

initial injection distribution. At high carrier gas flow rates, there

is insufficient time for the probe to reach a steady-state distribution

between vapor and polymer phases. The degree of peak spreading is

related to the rate of mass transfer occurring in the column, provided

that contributing instrumental factors, such as dead volume, are negligible.

The magnitudes of various gas phase mass transfer processes have been

estimated and their effects minimized in a series of studies on diffusion

of octadecane in polyethylene. The diffusion coefficient has been

determined for this system and found to be extremely sensitive to the

227
geometry of the polymer film present on the spherical support particles.

Knowledge of the film thickness distribution, in addition to its average

value, is critical to the experimental determination of reliable diffusion

coefficients by IGC. Future work will include studies of diffusion in

polymer systems with clearly defined geometry. IGC experiments on diffusive processes in glassy polymers will also begin.

Diffusion Coefficient of Medium Size Molecules in Semicrystal 1 ine

Polymers

Subtask 8 of Task 12138

A. Peterlin, F. L. McCrackin

An empirical correlation of the diffusion coefficient of a number

of molecules with sizes between N 2 and SF 6 in natural rubber and in

polyethyl enes of increasing crystallinity can be given by

D' = KDm

where K and m depend on the polymer but not on the penetrant. The

diffusion coefficients are given by this expression within a relative

error of 4.7 percent. This expression may be interpreted in terms of

the fractional free volume, f, concept of the material transport.

According to this model, the diffusion coefficient is given by

D = A exp(-B/f)

where B depends on the size and shape of the penetrant molecule while f

and, to some extent A, depend exclusively on the polymer. By introducing

this expression for D and D

1

, one obtains m = f/f 1

, which permits the

calculation of the ratio of the fractional free volume in the polymers

investigated. For the cases investigated, f of the amorphous component,

which is responsible for practically all the material transport, depends

substantially on the crystallinity. At the highest observed crystallinity

of 0.77, the fractional free volume seems to be only 67 percent of the

fractional free volume in polymer with the low crystallinity of 0.29.

The situation is still more extreme if one includes natural rubber which

does not contain any crystals. Polyethyl enes with crystallinity 0.77,

0.43, and 0.29 have a fractional free volume which is 0.58, 0.76, and

0.86, respectively, of the fractional free volume of the purely amorphous

natural rubber.

Measurement of Antioxidant Migration by Fluorimetry

Subtask 9 of Task 12138

F. W. Wang

The migration of antioxidants from polymer films is being studied

by extraction experiments. In an extraction experiment, a plane sheet

of polymer with uniform concentration of an antioxidant is immersed in a limited amount of well-stirred solvent. Then, the amount of the antioxidant

extracted by the solvent is determined at various times by fluorimetry.

228
Experiments were performed to measure the extraction on N ,

N

1 -diphenylp-phenylene-diamine (DPPD) by heptane at 22.0 °C from 0.27 mm thick

low-density polyethylene films containing 8.4 x 10 3 percent DPPD. The

results showed that all the DPPD had been extracted out of the films

within four hours and that the plots of the weight of DPPD extracted

against the square root of time were sigmoidal and non-Fickian. These

results and others to be collected will be compared with the predictions

of a theory being developed by Dr. F. L. McCrackin.

Excimer Fluorescence Technique for the Study of Polymer-Segment

Mobi 1 ity

Subtask 10 of Task 12138

F. W. Wang, R. E. Lowry

The study of polymer-segment mobility is of practical as well as scientific interest. Such a study will on the one hand contribute to

the design of polymeric reagents and on the other hand, shed some light

on "internal viscosity," an idea introduced by Kuhn some 35 years ago

and yet still argued about [1,2]. Therefore, we initiated a program to

measure polymer-segment mobility by a novel technique based on excimer

fl uorescence.

An excimer is formed by the association of an excited molecule with

another molecule in its ground state. Such an excimer is characterized

by a broad structureless fluorescence which is shifted to longer wavelengths

with respect to the fluorescence spectrum of the isolated molecule.

Similarly, excimer formation may take place by i ntramol ecul ar processes

in polymers carrying excimer- formi ng groups. Thus, excimer fluorescence

has been observed in dilute solutions of polymers such as polystyrene,

polyvi nyl naphthalene , and poly(l-naphthyl methacrylate).

We synthesized a random copolymer of methyl methacrylate and 1-pyrenylmethyl methacrylate as well as a random copolymer of methyl acrylate and

1 -pyrenylmethyl acrylate, the mole fractions of pyrene- 1 abel ed monomers

being 0.05 and 0.03, respectively. We then measured the fluorescence

spectra for dilute degassed solutions of these polymers at 22.0 °C in

ethyl acetate and in mixtures of ethyl acetate and glycerol tripropionate,

which have the same chemical nature but different viscosity.

For a given polymer, the value of I^/I^, The ratio of the fluorescence

flux emitted by pyrenyl excimers to that by isolated pyrenyl groups,

depends on polymer conformation as well as the rate constant k for the

diffusion-controlled association of an excited pyrenyl group and a ground-state pyrenyl group to form a pyrenyl excimer. However, by using

mixtures of solvents of the same chemical nature but different visocisty,

we were able to study the effects of solvent viscosity on 1^/1^ without

modifying the polymer conformation to any significant extent. Thus, at

the low enough temperature of our investigation, the ratio I^/I^ at

photostationary conditions was proportional to k [3]. Since k in turn

229

iwififinnuwffi
depends on the polymer-segment mobility, measurements of 1^/1^ as function of solvent viscosity allowed us to determine the effects of

solvent viscosity on the polymer-segment mobility.

We found that the experimental curves of the reciprocal of I^/I^

(or equivalently the reciprocal of k ) against the solvent viscosity

were concave downward. This finding agrees with Cerf's proposal [4]

that the highly diversified segmental motions of linear polymer chains

belong mainly to two classes which follow diffusional and non-di f fusional

behavior, respectfully, and which may coexist, the former having the

reciprocal of the characteri sti c rate constant proportional to the

solvent viscosity and the latter having the reciprocal of the characteristic

rate constant a linear function in the solvent viscosity with a non-zero constant attributed to "internal viscosity."

Additional experiments will be performed to study the variation of

polymer-segment mobility with polymer structure, solvation of polymer,

and polymer-polymer stereocomplex association.

References

[1] H. Ott, R. Cerf, B. Michels, and P. Lemarechal , Chemical Physics

Letters, 24, 323 (1974).

[2] W. H. Stockmayer, Pure Appl. Chem. Supplement, 8, 379 (1973).

[3] H.-J. Galla and E. Sachmann, Biochim. Biophys. Acta, 339, 103

(1974).

[4]

R. Cerf, Chemical Physics Letters, 22, 613 (1973).

Assessment of Transport Mechanisms for Radon in and Through Building

Material

Subtask 11 of Task 12138

R. J. Rubin

Accumulation of radioactive radon gas in buildings poses a health

hazard. High levels of radon are encountered in certain "hot" geological

areas where it emanates naturally from the ground. Certain building

materials, such as gypsum board, also contain higher than average amounts

of radon. Under an interagency agreement with the EPA, NBS has very

recently undertaken the task of studying radon transport in building

materials. It involves a cooperative effort between three NBS Centers:

Radiation Research, Building Technology, and Materials Science. The

initial phase of this project is to critically assess the current state

of knowledge of radon transport through or emanation from building

materials. The Polymer Science and Standards Division's role is to assess current transport mechanisms and models.

230
DIELECTRIC PLASTICS DESIGN AND PERFORMANCE

Task 12139

Trends in dielectric application of polymers include use of higher

working voltages in electrical apparatus and transmission lines to

conserve materials, save space, and reduce weight. This work provides

manufacturers (polymer manufacturers, film fabricators, transducer

manufacturers), trade associations (EPRI), and Government agencies (DOE,

DOD) with data, measurement methods, and concepts which identify limitations

in polymer performance traceable to manufacturing practices. For example,

steam curing of extruded polyethylene insulated cables results in lifetime

limiting voids and inclusions. With a trend toward increased use of

underground transmission of electric power, improved insulation performance

is required. Data and recommendations from this work go directly to

cable manufacturers and funding organizations (i.e., EPRI, DOE) who are able to specify and require manufacturing changes leading to improved

products.

Other trends are new, rapidly growing applications of polarized

polymers as pyro- and piezoelectric transducers. Transducer manufacturers

as well as private and Government transducer users (DOD, EPA, HHS) need

reliable information connecting polymer structure and polymer performance

to the design of improved transducers. This work will help transducer

material and device manufacturers design and develop commercial polymer

transducers for use in health and safety applications (pulse monitors,

therapeutic and diagnostic sound measurements, auto crash sensors,

prosthetic fitting devices, nontoxic anti fouling coatings, mine disaster

warning devices) and in the areas of national security (microphones,

hydrophones, intrusion detectors, ultrasonic and infrared imaging devices,

fusing devices, etc.). Important scientific opportunities of this work

include breakthroughs in understanding the basic factors in electrical

failure of polymers and discovery of novel measurement methods which are becoming possible with newly developed polymers. For example, this work

attempts to show how polymers interact with electronic and ionic charges

and how structure can be modified to optimize piezoelectric and semiconducting properties.

Polymer Insulation for Superconducting AC Power Transmission Cables

Subtask 1 of Task 12139

F. A. Khoury, F. I. Mopsik, S. J. Kryder, L. H. Bolz

This project, sponsored by and carried out in collaboration with

Brookhaven National Laboratory (BNL) with DOE funds, is part of a program

for evaluating the suitability of various types of polymer films for use

(in tape form) as the electrical insulation in high power superconducting

a.c. transmission cables operated at 6-8 K. Such cables, in which the

superconductor is Nb 3 Sn, are currently under development at BNL. Among

the guidelines used for selecting the insulation for such cables is that

the dielectric constant (s) should be 2.5 or less_and that the dielectric

loss (tan 6) should preferably not exceed 20 x 10 6 at the cable operating

temperature range and 60 Hz.

231
This subtask is primarily concerned with the measurement of the

dielectric properties (s, tan 5) of polymer films at cryogenic temperatures.

These measurements, for which NBS has a unique instrumental facility,

are coupled with studies of aspects of the fine structure of the films

in an effort to determine the influence of various structural parameters

(e.g. , crystallinity, molecular orientation, voids) on the dielectric

properties of the films. In addition to determining whether specific

types of commercially available films meet the established criteria for

dielectric properties, these studies are aimed at providing data relevant

to the design and production of films exhibiting optimum dielectric

properties for the intended end use. In a less extensive effort, the

compressibility of the polymer films is measured. This latter feature

is relevant to the determination of the optimum conditions (e.g., tape

tension) necessary for winding the films (sliced into tapes) around the

cable core, so as to yield a cable exhibiting appropriate flexibility

for winding onto storage drums 10 feet in diameter.

In FY80, this project was mainly concerned with studying laminates

made from two layers of a new, ^ 50 pm thick polypropylene bound together

by a polyurethane layer. Measurements made last year indicated that

these laminates had substantially lower loss than ones made from older,

thinner (25 pm) pojypropyl enes and could meet the requirement that tan 6

not exceed 20 x 10 6 at 6-8 K, which the older ones could not.

Dielectric loss studies were made on two series of laminates. The

two series had different yellow dye concentrations (0.7 percent and one percent) in order to see if the presence of dye affected the dielectric

loss. The dye is added for visual monitoring of tapes made from the

laminates as they are wound_to form the cable insulation. In both

cases, tan 6 was 12-15 x 10 6 at 6-8 K, indicating that the added dye

did not affect the loss and that the loss criterion could be met.

Another series of measurements was made on laminates of nominal 80,

100, and 120 pm thickness from polypropylenes of 40 and 60 pm thickness.

In addition, the 60 pm polypropylene film was measured separately.

These graded thicknesses for the laminates will be used in a cable made

for voltage testing to better distribute the voltage stresses across the

insulation. The results showed that the loss at 6-8 K decreased with

increasing thickness showing that the polyurethane layer, which had a constant thickness in all the laminates, contributed significantly to

the loss. The_values for tan 6 were 18-20 x 10 6 for the 80 pm laminate

and 10-12 x 10 6 for the 120 pm laminate. The loss for the polypropylene

alone was 6-7 x 10 6

, one of the lowest values seen for any polypropylene.

These data were then combined to show that the suitably low loss of the

present laminate as compared to the older, less satisfactory, laminates

was due both to the intrinsically lower loss of the polypropylene itself

and to the reduction in the amount of polyurethane present, since only

one bonding layer was needed.

In other dielectric measurements, an epoxy composite that was intended for use in bushings was measured for dielectric loss.

232
All the laminates measured dielectrically were also measured for

compressibility when stacked in layers. These data are necessary for

predicting cable bendability. The series of graded laminates was also

examined microscopically. There was a considerable reduction in void

content in the polyurethane layer compared to earlier laminates. This

indicates better control over the laminating process and a reduction in

possible breakdown problems under voltage stress.

Successful improvement of these materials is traceable in large

part to the measurements and analysis from this work which is fed back

to the manufacturers to guide processing changes.

Polymer Tape Insulation for Oil Impregnated AC Power Transmission

Cables

Subtask 2 of Task 12139

F. A. Khoury, F. I. Mopsik, S. J. Kryder, L. H. Bolz

Oil impregnated paper (cellulose) tape has been, for many years,

one of the most commonly used types of electric insulation in high power

ac transmission cables. The current and projected needs for more efficient

power transmission systems have elicited considerable interest in the

development of oil impregnated or oil filled cables operated at 700-1000 KV,

in which polymer tape insulation will be used instead of the conventional

paper tape which is unsuitable because of its large dielectric loss.

In a project sponsored by Brookhaven National Laboratory with DOE

funds, a program has been initiated in the Polymer Science and Standards

Division for evaluating the suitability of various types of impregnated

ac transmission cables. The goals of this study are: (a) the measurement

of the dielectric constant and dielectric loss of candidate films between

273 K and 423 K; (b) the determination of the dependence of the dielectric

loss on the fine structural character!' si tics of the films; and (c) the

specification of the dielectrically most suitable type of film for the

intended end use.

The dielectric measurements carried out this past year have focused

on a series of drawn polyethylene tapes prepared for Brookhaven by

Battel le Institute. Three different base polymers were used under two

different rolling conditions. The conditions were a roll temperature of

298/303 K with a thickness reduction ratio of 5-7, and a roll temperature

of 348 K with a thickness reduction ratio of 8.3. All the samples were

measured under standard temperature cycling to check the effects of

thermal cycling.

The three different polyethyl enes showed quite different loss

characteristics. One of them exhibited a low level of loss (tan 6 less

than 30 x 10 6

) that did not change much on thermal cycling. The other

two had an initial tan 6 at 303 K of 80 x 10 6 and 50 x 10 6 all at

100 Hz. The latter two showed substantial reductions in loss at 303 K with thermal cycling to 353 K, 373 K, and 383 K in three successive sets

of measurements. All the specimens showed substantial changes in dimensions as reflected in the measured capacitance. The reason for these

233
loss differences as well as the changes in loss with thermal cycling is

unknown. One possibility may be differences in the raw polymer (cleanliness

and additive content). There were some hints that relatively volatile

materials did contribute to the loss. No correlation was found with

sample density.

The density, wide angle x-ray diffraction, and small angle x-ray

diffraction of the samples were measured both before and after thermal

cycling. The most notable effects were found in the density. The tapes

rolled at 298/303 K had an increase in density correspond!' ng to an increase in crystallinity from ~ 66 percent to ~ 75 percent, while those

rolled at 348 K had an increase of crystallinity of ^ 72 percent to ^ 77 percent. Some samples of one of the tapes rolled at 298/303 K were thermally cycled as in the dielectric measurements and forwarded to

Brookhaven for measurement of thermal conductivity changes induced by

the thermal cycling. These data are important for predicting the dissipation of heat generated during power transmission.

The results summarized above, coupled with earlier measurements on the effect of thermal cycling on the dielectric properties of the experimental

polyethylene tapes made by Battel le Institute, have emphasized the need

for modifying processing conditions in order to produce tapes which are dimensionally and dielectrically stable to thermal treatments in the

range 273-383 K. It is expected that the normal operating temperature

of the cables will be 355-365 K.

Structure and Performance of Piezoelectric Polymers

Subtask 3 of Task 12139

G. T. Davis, 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. The interest in the use of polymeric

transducers continues to increase as evidenced by the requests from

other Government agencies, by the large number of requests for information

by mail, phone, and personal visits, and by the 20 papers presented at

the American Physical Society meeting in March 1980.

During the past year, considerable effort was expended in the

preparation and character]' zation of gamma phase PVDF in order to investigate

its poling character!' sti cs . A surfactant, si 1 oxane-oxyal kyl ene block

copolymer (L-520) produced by Union Carbide was deposited from ethanol

234
solution onto PVDF powder so as to comprise two weight percent additive.

The alpha phase which forms upon cooling from the melt is transformed to

gamma phase when heated in the presence of the surfactant at l°/min to

176 °C. Films without the additive, subjected to the same thermal

treatment, melt and recrystallize in the alpha form when cooled. X-ray

diffraction is the most convenient means of distinguishing between the

two crystal phases. (IR and DSC are less definitive.) Films of alpha

and gamma phases were subjected to the same poling conditions, and the

piezoelectric and pyroelectric responses were measured. The much larger

response from gamma phase for all electric fields less than 1.25 MV/cm

confirms that this is a polar crystal phase. The value of 1.3 nC/cm2 K for pyroelectric coefficient after poling for 10 3 seconds at 80° and

1 MV/cm is almost the same as that reported for unoriented beta phase

obtained by pressure quenching and poled at the same field for one hour

at 23 °C. For values of electric field 750 kV/cm and greater, the alpha

phase undergoes the electric field induced phase transition to a polar

form, so that at 1.25 MV/cm the responses from alpha and gamma phase

films are comparable. It has not been possible to pole at fields greater

than 1.25 MV/cm because of electrical breakdown. In the course of this

investigation we discovered that simply orienting the polymer film

reduces electrical conductivity by more than a factor of 100. An improvement

in electrical breakdown strength is indicated but not fully quantified

at this time. Because of the field-induced phase transition of alpha

phase, there seems to be no practical advantage for promoting the formation

of gamma phase unless one must be confined to low poling fields. A

detailed report on these results in in preparation.

We have also poled PVDF as it undergoes the alpha to gamma phase

transition in the vicinity of 176 °C for the purpose of studying the

stability of the resultant piezoelectric film. Unfortunately, the

breakdown strength at these temperatures is about 400 kV/cm so that only

low activity is achieved, and the response resulting from these low

poling fields decays with time even at room temperature.

We have recently succeeded in increasing the piezoelectric and

pyroelectric charge response (as opposed to voltage response) of PVDF by

improving the coupling between the polar crystals and the external

electrodes. A 0.1 M solution of tetrabutyl ammonium bromide in dichl oroethane

was diffused into a poled film which greatly increases the conductivity

of the film. The initial pyroelectric activity of 2.4 nC/cm2 K increased

to 3.3 nC/cm2 K. (Solvent without the electrolyte has no effect.) As

the volatile solvent is removed, the response returns to its initial

value but can be increased again by the sorption of dichl oroethane from

the vapor phase. A more highly poled sample subjected to similar treatment

increased from an initial value of 3.3 nC/cm2 K to a maximum value of

4.4 nC/cm2

K. When the exposure time to the electrolyte solution was increased from 1 day to 3 days at 23 °C, the activity as we measure it was greatly reduced, presumably because the impedance of the polymer

film becomes comparable to or less than that of the measuring circuit.

Preliminary experiments using the same salt in the much less volatile

1 ,6-dichl orohexane have shown similar enhancements without loss of the

enchanced activity with subsequent storage time at ambient conditions.

These investigations are continuing.

235
In the past year we published a summary of a cooperative six-site

model for ferroelectric switching in p-phase PVDF. This model predicts

the essential features of polarization and IR transmission hysteresis

curves and data on crystal plane reorientation with applied field.

These data all apply to changes that occur well below the order-disorder

(or Curie) transition implicit in the model and occurring in PVDF well

above the melting point. This past year, Dr. Furukawa published data on

a copolymer of PVDF and trifl uoroethylene which showed a Curie temperature

at 70 °C. It was possible then to extend the model calculations to the

transition region. The experimental observation that the critical

switching field decreased with increasing temperature and vanishes at

70 °C is consistent with the model, as is the anomalously high dielectric

constant which has a maximum of about 70 at 70 °C. Using structural

information, this dielectric constant anomaly was calculated for the

six-site model. As expected, the calculated dielectric constant for the

crystal phase was considerably larger than that for the semi crystal 1 ine

sample. This occurs in any composite since the lower dielectric constant

component reduces the electric field in the higher dielectric constant

component. Because the particle shapes and orientations are so important

in composite dielectrics, we are not able to calculate exactly what the

semi crystal! ine sample dielectric constant is, even if we know the

dielectric constants of the components. However, it looks as if there

are some significant trends in the data not predicted by the model. A

complete publication of the calculations to date is in preparation.

Automated Dielectric Measurement

Subtask 4 of Task 12139

F. I. Mopsik, S. J. Kryder, S. C. Roth

The automated dielectric spectrometer is nearing completion. This

instrument will record the transient response of a dielectric sample in

real time and using numerical transforms will automatically determine

the dielectric constant and loss of the sample over the frequency range

of 10_kHz to 0.001 Hz or below. The instrument should have a resolution

of 10 5

, which is an order of magnitude improvement over most designs.

This will allow determination of the dielectric properties of low loss

polymers with much greater speed than previously possible.

Work done in FY80 includes completion of the charge detector. This

detector can resolve 0.1 pC with a 10 ps rise time and for time up to

100 s. A major challenge that was overcome was the design of a reset

circuit so that the output could be zeroed with negligible charge transfer

or drift. In addition, the final interface boards have been acquired.

Currently, the computer interconnections are being made prior to testing

as a complete unit.

In addition, some of the programming for data treatment has been

tested by its use with the thermal pulse experiment. In particular, the

idea of data selection and interpolation for optimal computation has

been successfully incorporated in the thermal pulse experiment and will

236
be used in the spectrometer. This allows the actual data sampling to be

done in an experimentally convenient manner with a sufficient excess of

points to obtain significant noise reduction.

ASTM Activities

Subtask 5 of Task 12139

W. P. Harris

Mr. Harris chaired the final meeting of his six-year chairmanship

of ASTM Committee D-9, Electrical Insulating Materials, at Dearborn in

October 1979. There he received an award of appreciation for his excellent

service. He attended the March 1980 ASTM meeting in Dallas and continues

to serve as a member of the executive committee. Current activity in

D-9 consists of revising D-150, which is one of the Committee's most

widely used and cited testing documents.

Polymer Sensors for NDE

Subtask 6 of Task 12139

50 S. Edelman, S. C. Roth

The 1980 NDE work of the Electrical Properties Group consisted of

the use of polymer sensors to measure dynamic elastic moduli and to

detect wear in airplane control cables.

Making use of the sensitivity, low density, and flexibility of

piezoelectric polymer strain gauges, we have worked out a non-resonant

method for measuring both the real and imaginary parts of both the

dynamic Young's modulus and the dynamic shear modulus of structural

materials in the form of long, thin rods. All four quantities can be

obtained as continuous functions of both frequency and static load. The

frequency can be varied over a wide range, and the static load can be

varied from a large compressive value through zero to a large tensile

val ue.

The method can be used to study the basic dynamic properties of

materials. It should be especially useful in studying composite materials

and polymers, materials whose dynamic properties are likely to vary with

static load. In the case of composite materials, variation of damping

character!' sti cs with static load can be expected to be a sensitive test

of the quality of the bonding between components. The method can be

used to provide basic engineering data needed for designing structures

which are to be subjected to dynamic stresses or for which particular

levels of internal damping must be obtained.

Since all measurements are made on a single specimen under identical

conditions (except for the type of excitation) any deductions about the

internal structure are free of the uncertainties introduced where measurements

at different frequencies require different specimens and where measurements

of the different moduli require different apparatus. The method can be

used for nondestructive evaluation of structural elements either for

237
compliance with design specifications or for monitoring a change in

properties during service. A paper describing the method was presented

at the April 1980 meeting of the Acoustical Society of America. Support

for a laboratory installation to apply the method is being sought.

The study of airplane control cables is being performed on an apparatus in which the cable, under tension, is pulled around a small

pulley by a cam which converts the rotation of an electric motor to

reciprocating motion. A polymer sensor, attached to the cable near the

pulley, detects the noise of the motion of the strands as they deform on the pulley. The sensor can be removed from the cable and reattached

readily so that the same sensor can be used to compare different cables

or different conditions. An elaborate mechanical filter eliminates

motor noise from the signal. A spectrum analyzer operates on the sensor

signal, and changes in the spectrum are monitored to detect the effects

of fatigue and wear.

Polymer Stress Gauge For Intaglio Printing Press

Subtask 7 of Task 12139

M. G. Broadhurst, S. C. Roth, S. J. Kryder, A. S. DeReggi , S. Edelman

This work, which is supported by the Bureau of Engraving and Printing,

U.S. Department of Treasury, involves the development of a gauge to

measure the dynamic pressure at critical points in the presses used to

print money. The first phase of the work was completed last year. The

accomplishments of the first phase included measurement of the width of

the area of contact between the two cylinders of the press, the duration

of contact of a point on the upper cylinder with the lower cylinder, and

a qualitative (uncalibrated) determination of the change of the pressure

with time during contact.

This year work began on the second phase which is to provide calibrated

pressure measurements. Specifications for telemetry have been written

and equipment ordered. Dedicated data processing equipment has also

been ordered. Preliminary design and construction of polymer gauges is

well along. A start has been made on design of a field calibrator for

checking the calibration of pressure gauges after installation.

Ultrasonic Hydrophone

Subtask 8 of Task 12139

A. S. DeReggi, S. C. Roth, J. M. Kenney, S. Edelman

This project is partly sponsored by the Bureau of Radiological

Health, which is contributing the services of a guest worker. One

objective of the project is to develop a piezoelectric polymer hydrophone

for characterizing, point-by-point, the acoustic field beamed by ultrasonic

transducers, such as those used in biomedical equipment. Accurate

knowledge of the details of the acoustic field is not otherwise obtainable.

The knowledge can be used to ensure both the safety and adequacy of

ultrasonic dosage and for research in ultrasonic treatment.

238
During this year, the performance of several prototype hydrophone

probes has been investigated thoroughly, with regard to both frequency

response and performance stability at room temperature. The sensitivity,

the broadband responsivity , the non-perturbing properties, and the

long-term stability have been judged good enough for the Bureau of

Radiological Health to adopt the probe as a standard probing hydrophone.

A paper is currently under review for publication in the Journal of the

Acoustical Society of America. In addition, a patent is being sought.

Several prototype annular arrays have been constructed and tested.

These arrays consist of concentric ri ng-detectors formed as common parts

of a tensioned polymer membrane. They are being used in ultrasonic

research to verify ideas in the theoretical modeling of disc-shaped

ultrasonic projectors. The geometry of the polymeric arrays allows the

measurement with unprecedented precision of the relative contribution of

the ring diffraction term and the piston plane wave term of the projected

acoustic beam. This work is the subject of the Ph.D. dissertation of our guest worker, Gerald Harris of the Bureau of Radiological Health,

who is also a part-time student at Catholic University. A preliminary

account of this work has been submitted for presentation at the 25th

Annual Meeting of the Institute of Ultrasound in Medicine in New Orleans

on September 15-19, 1980, and for publication in the Proceedings of that

Conference.

Durability of Piezoelectric and Pyroelectric Activity in PVDF

Subtask 9 of Task 12139

J. M. Kenney, M. G. Broadhurst

This work was initiated with the Naval Undersea Systems Command

because of their interest in widespread use of polymer hydrophones by

the U.S. Navy. Since good durability of activity is crucial for this

application and since long time testing makes it difficult to judge the

effects of structural or processing modifications on durability, we have

developed a short time test procedure which will give a rapid measure of

relative durabilities of different samples. The test consists of continuously

recording pyroelectric activity while the temperature is being increased

linearly to the melting point of the sample. Samples show a broad

maximum in activity vs. temperature. We use the temperature at which

the activity falls as a measure of durabi 1 i ty--the higher the temperature

the more durable the sample.

Dramatic differences were seen between samples of PVDF and a copolymer

of PVDF with tetraf 1 uoroethyl ene. The temperature at which the activity

falls to zero is 100 °C for the copolymer and 170 °C for the PVDF.

While this short time test will be useful for comparing effects of

different structures and treatments, it must be calibrated with longer

time aging studies. This year we made measurements of 38 PVDF samples

which had been stored at room temperature for 15 months. It was found

that the activity of the specimens as a fraction of the initial activity

was 0.91 ± 0.05. The magnitude is similar to that measured at two D0D

laboratories in previous studies.

239
The mechanism of loss of activity of PVDF has not yet been established,

and these measurements should provide valuable data for the development

of a suitable aging model.

Space Charge Studies

Subtask 10 of Task 12139

A. S. DeReggi , F. I. Mopsik, M. G. Broadhurst

The static and kinetic effects of space charge in polymers subjected

to electric fields continues to be of interest as different groups in

the USA and outside are developing new methods to measure these effects.

In the poling of piezo- and pyroelectric polymers where near-breakdown

fields are applied temporarily and in the standing-off of high potentials

by polymeric electrical insulation where moderate fields are sustained

for extended periods of time, space charge is either initially present

as an ionic impurity, is produced through field-enhanced degradation, or

is injected across the el ectrode-polymer interface. The space charge

typically distorts the applied electric field and gives rise to regions

of field concentration. In the case of insulation, there is a resultant

acceleration of the aging process leading to premature breakdown. In

the case of piezoelectric polymers, there is a resultant non-uniform

distribution of polarization which in combination with a small but

finite conductivity gives rise to unusual transduction phenomena.

Until recently, only qualitative information was obtained about the

space charge and polarization distributions because of the preliminary

stage of development of the methods used to measure these distributions.

For example, using the thermal pulse method we were able to show that in

PVF subjected to a poling voltage, polarization tends to reside near the

negative poling electrode for a wide range of poling voltages and poling

times and furthermore, that a threshold mean field of ~ 150 Wpm must be

exceeded in order for significant remnant polarization to be found.

Extremely weak remnant polarization was measured for mean fields as low

as 24 V/pm. We suppose that positive space charge plays an important

role in producing a distribution of electric fields in the sample and

hence a distribution of applied poling fields. These observations are markedly different from those made on PVDF where polarization tends to

reside near the positive poling electrode (presumably due to negative

space charge) and where there is a more gradual increase in remnant

polarization as a function of the mean applied field. A paper discussing

the role of space charge on the poling behavior of PVF has been written

with a recent guest worker, Professor Sidney Lang of the Ben Gurion

University (Israel), and has been submitted for publication in Ferroel ectrics.

We have recently been able to acquire the transient charge response

from the thermal pulse experiment in digital form, and the computer

programming for data analysis has been completed and tested. From the

data, one extracts the coefficients of a Fourier series representing the

polarization distribution in the film. When data can be obtained by

illuminating first one side of the film and then the other, the sum and

difference of the two signals yield only even or only odd Fourier coefficients

240
This separation of terms facilitates a good determination of the thermal

time constant i for the sample. An important feature of the program is

that data are not chosen at equal increments of time but are taken at

times chosen to yield the most information about the relaxation time of

the nth term which varies as x/n 2

. When data are available by pulsing

alternate sides of the film, as many as ten Fourier coefficients can be

determined. This means, very roughly, that the "resolution" is about

one-tenth of the film thickness. This amount of detail in the charge

and/or polarization distribution is expected to be of great value in

directing the development of models for non-uniform field distribution

during the early stages of poling.

Piezoelectric Polymer Fuzing

Subtask 11 of Task 12139

S. C. Roth, A. S. DeReggi , S. Edelman

This project is sponsored by the U.S. Army Armament Research and

Development Command. It is developed from previous work by NBS in

cooperation with Frankford Arsenal reported in NBSIR 75-724 (R). NBS is

to assist ARRADCOM to determine the feasibility of using pi ezoel ectric

polymer film in impact sensors for fuzing applications in several particular

geometries.

An equation was developed describing the performance of piezoelectric

polymer in fuzing. When reasonable values, supported by the results of

impact studies, were used in the equation, it was predicted that sufficient

energy would be released to detonate a 105 mm high energy antitank

round.

A technique using heat, vacuum, and pressure was developed for

shaping piezoelectric polymer to the inside of an ogive (forward part of

a munitions casing). An ogive instrumented in this way was delivered to

ARRADCOM for testing.

A draft of the final report has been sent to ARRADCOM for comment

and approved by them.

Development of Piezoelectric Polymer Stress Gauges for Rock Studies

Subtask 12 of Task 12139

S. C. Roth, S. Edelman

This work, funded by the Denver Mining Research Center of the

Bureau of Mines, is a continuation of work described in the report for

last year to measure noise from grinding together of rock specimens.

Most of a series of polymer gauges for measuring rock noises were developed at NBS and delivered last fiscal year. The remaining gauges

have been constructed and will be delivered this fiscal year. The

gauges have been effective in detecting and measuring the acoustic

emission from rock samples under stress. Also, they have been found to

241
survive collapse and crushing of the rock specimens unless a crack

develops directly across the active area. Future work on rock and soil

transducers is expected to result from tests on these transducers.

Thick Electrode Transducers

Subtask 13 of Task 12139

A. J. Bur, M. G. Broadhurst

The fabrication of transducer specimens of PVF 2 with thick, well

adhering electrodes was attempted. The objective was to study the

influence of the mechanical properties of the electrodes on the PVF 2 transducer behavior. It is expected that the hydrostatic response will

be enhanced by a factor of two to three if the electrodes maintain their

own integrity and exert a stress on the polymer film during temperature

and/or pressure changes. Transducers previously fabricated in our laboratory have had very thin evaporated electrodes, several hundred

angstroms thickness. Because the electrode is so thin, the mechanical

properties of the polymer substrate dominate.

»

' Metals such as Ni , Au, Ag, and Cu have elastic moduli which are 30 to

40 times larger than that of PVF 2

. A metal electrode of 0.4 pm

thickness will have the same rigidity as 12 pm of PVF 2

. A metal electrode

of 4 pm thickness will have 10 times the rigidity of the polymer.

Relative to the polymer, a thick electrode can be considered rigid so that when the polymer contracts, a stress between electrode and polymer

develops. The predicted effect of this stress is to enhance the change

in the thickness of the polymer film by a factor of two or three relative

to the change with thin electrodes.

Previous attempts to detect a significant electrode thickness

effect have been unsuccessful, presumably due to poor adhesion between

polymer and metal. This year we have made measurements on a series of

specimens furnished by Bell Telephone Laboratories which showed a systematic

dependence of piezoelectric response due to stretching in the plane of

the film with different thicknesses of gold making up the electrodes.

As in previous studies, we have yet to find a large difference (more

than 10-20 percent) in pyroelectric response or hydrostatic piezoelectric

response before and after the gold electrodes are removed. The differences

we see in the activity of these specimens with electrode thickness seem

to be due in part to differences in sample polarization.

We suspect that stiff electrodes inhibit polarization of these

films by restricting the local strains needed to accommodate changes in

crystal phase and orientation which occur as part of the poling process.

We are presently conducting experiments to measure this polarization for

specimens with differing electrode stiffness to characterize this effect.

We are making sure that the polarization measurements made during poling

agree with those made while the specimens are depoled (melted) and will

then depole the Bell Lab specimens to determine their state of polarization.

242
As a final attempt to measure thick electrode effects, we have

arranged to obtain samples from EMI with well attached electrodes of

differing thickness. If these do not show the expected effects, we will

be forced to conclude that the effect does not exist, though no explanation

for its absence has yet been found.

Fabrication of Piezoelectric Polymer Film

Subtask 14 of Task 12139

A. J. Bur, M. G. Broadhurst

The Department of the Navy is supporting a project to fabricate

piezoel ectrical ly active PVDF specimens with thicknesses of 0.79 mm

(31 mil). A thick transducer is desired because it will have a lower

capacitance than the thin film PVDF transducers which we have routinely

prepared and a correspond!' ngly higher voltage response for a given

strain.

The problems with making thick polymer transducers are the large

stresses needed to stretch thick samples and the large voltages needed

to apply a polarizing field to them. Large Instron machines were used

to stretch our materials while the high voltage group at NBS assisted in

poling them. Initial failures at poling thick samples were due to low

breakdown strength which we suspected was an inherent disadvantage of

thicker, more defect prone samples. Further investigation, however,

showed that there was a large difference between oriented and unoriented

material. The oriented material is able to withstand poling fields of

1 MV/cm so that acceptable transducer activity can be achieved. We have

not established the quantitative difference in breakdown strength between

unoriented and oriented PVDF, but qualitatively it can be concluded from

these observations that such a difference exists.

To better understand this dependence of breakdown strength on stretching, we measured the resistivity of stretched and unstretched

PVDF from several sources. The data distinctly show that the resistivities

for unoriented PVDF are lower than those for the oriented material by at

least an' order of magnitude. While we have not established a relationship

between resistivity and breakdown strength, we conclude that the state

of orientation is an important factor which affects the electrical

properties of PVDF.

Molecular orientation is extremely important to making successful

thick polymer hydrophones. These thick hydrophones are equal to, and

may exceed, the performance of present state-of-the-art ceramic hydrophones.

The use of this effect to study the basic nature of conduction is equally

important scientifically.

243
Diffraction From Nonperiodic Structures: The Molecular Conformation

of Polytetrafl uoroethylene (Phase II)

Subtask 15 of Task 12139

E. S. Clark1

, J. J. Weeks, R. K. Eby

University of Tennessee

The crystal structure of polytetrafl uoroethyl ene has been a subject

of discussion among spectroscopi sts , crystal 1 ographers , and others.

However, the determination of structure in synthetic polymers is made

difficult by the lack of resolution in the diffraction data. The diffuseness of the reflections observed in most x-ray fiber patterns results

from the small size, misorientation, and imperfect lattice nature of the

crystallites. This lack of resolution leads to poor accuracy in measurement

of peak position and makes determination of layer line heights difficult

with a corresponding loss of significant figures in evaluation of the

repeat distance for the molecular conformation. In helical conformations,

the repeat distance may be of considerable length or indeterminate and,

in effect, nonperiodic. Remarkable electron diffraction patterns of the

low temperature form of polytetrafl uoroethyl ene have been obtained which

exhibit layer lines sharply resolved to the 26th order. These patterns

permit accurate measurements of the layer line heights. Equations have

been developed to relate these heights to a molecular conformation

defined in terms of an incommensurable helix of ratio, r = u/t, defining

a conformation of u motifs regularly spaced along t turns of the helix.

The electron diffraction data yield a molecular conformation of r = u/t = 2.1

with the molecule slightly untwisted from the previously assigned

conformation of r = 13/6 = 2.167. The newly determined conformation

corresponds within the limits of error to r = 948/439. However, the

practice of expressing a helical conformation in terms of some commen- surable ratio, u*/t*, is questionable. If the helical conformation is

not expressed accurately in terms of simple smalnumbers, it is preferable

to define the conformation in terms of the ratio, r, limited to the

number of significant figures. This point is made tellingly in the

present case where a change of one standard deviation in r. changes u*/t*

from 948/439 to 54/25. Furthermore, the error limits admit 82 other

possibilities for t* < 500.

Order-Di sorder Transitions in Polytetrafl uoroethyl ene Subtask 16 of Task 12139

J. J. Weeks, I. C. Sanchez, C. I. Poser 1

, R. K. Eby

1 Guest worker, University of Massachusetts

The phase diagram of polytetrafl uoroethylene has been enlarged by

differential scanning calorimetry to include the concentration of hexafluoropropylene comonomer units. The two transitions near 292 and 303 K in

the homopolymer move to lower temperatures with increasing concentration

and apparently become one at a small concentration. Analysis of the

data for this single transition yields 295 K for the temperature and

244

S
13.2 J/g for the heat of transition of an infinitely large homopolymer

crystal. The heat of transition associated with the formation of a crystal defect is 0.021 eV. The qualitative features of the transitions

can be accounted for by a mean-field model which involves two order

parameters corresponding to planar units and helix reversals. This

model yields two transitions which move closer together and to lower

temperatures with increasing comonomer concentration. Decreasing lamellar

thickness will have a qualitatively similar effect.

245

Other Activities of the

Polymer Science and Standards Division

Invited Tal ks

Experiments on Non-Linear Elasticity

Short Course on Continuum Mechanics, NBS, Gaithersburg, Maryland

E. A. Kearsley

July, 1979

Dental Material s--Their Selection and Handling Techniques in

1979-80

Travis Air Force Base, Solano, California

N. W. Rupp

September 5, 1979

Crystal Disorders in Copolymers of Tetrafl uoroethyl ene and Hexafl uoropropylene

American Chemical Society, Washington, D.C.

R. K. Eby, E. S. Clark, and J. J. Weeks

September 12, 1979

Dental Material s--Thei r Selection and Handling Techniques in

1979-80

Scott Air Force Base, Saint Clair, Illinois

N. W. Rupp

September 12, 1979

Molecular Interpretation of the Load-Elongation Curve of Crystalline Polymers

ACS Symposium on Stress-Cracking of Plastics, Washington, D.C.

A. Peterlin

September 14, 1979

Transport Phenomena and Polymer Morphology

IUPAC Symposium on Polymers, Mainz, West Germany

A. Peterlin

September 18, 1979

Seminar on Clinical Research

University of Minnesota, Minneapolis, Minnesota

N. W. Rupp

September 18, 1979

Raman Frequencies and Intensities of Longitudinal Acoustic Modes

of Polymers

University of Massachusetts, Amherst, Massachusetts

B. M. Fanconi

September 21 , 1 979

Operating Techniques With Recently Introduced Dental Materials

University of West Virginia, Morgantown, West Virginia

N. W. Rupp

September 21 , 1 979

i 247
Application of Varied Heating Rate Methods to Polymer Degradation

Reactions

Ninth North American Thermal Analysis Society Conference, Chicago,

Illinois

J. H. Flynn

September 25, 1979

Polymer Morphology and Chain Transport Mechanisms

Boris Kidric Institute of Nuclear Sciences VINCA, Belgrad,

Yugoslavia

D. H. Reneker

September 25, 1979

Recent Developments in Dental Materials and Their Handling

Techniques

Lackland Air Force Base, San Antonio, Texas

N. W. Rupp

September 27, 1979

Properties of Polymers Including Chain Transport and Piezoelectric

Effects

Josef Stefan Institute, Ljubljana, Yugoslavia

D. H. Reneker

September 28, 1979

The Diversity in the Habits Exhibited by Polymer Crystals Grown

From Solution

Leeds University, Leeds, England

F. A. Khoury

October 2, 1979

Dynamic Scattering From Polymer Solutions

University of Michigan, Ann Arbor, Michigan

C. C. Han

October 5, 1979

Non-Linear Behavior of Viscoelastic Rubbers

Firestone Research Laboratories , Akron, Ohio

L. J. Zapas

October 12, 1979

Type II Diffusion in Glassy Polymers

Laboratory Technology of Polymers and Rheology, Naples, Italy

A. Peterlin

October 19, 1979

Order-Di sorder Transitions in Polytetraf 1 uoroethyl ene: Experiment

and Theory

Institute of Basic Technical Problems, Warsaw, Poland

R. K. Eby

October 22, 1979

248
Impregnation and Void Filling of Porous Polymer Tape With Dielectric Oil

Conference on Electrical Insul ationand Dielectric Phenomena,

White Haven, Pennsylvania

A. J. Bur

October 23, 1979

Transport Phenomena and Polymer Morphology

Laboratory Technology of Polymers and Rheology, Naples, Italy

A. Peterlin

October 23, 1979

Ferroelectric Polarization in Polymers

Conference on Electrical Insulation and Dielectric Phenomena,

White Haven, Pennsylvania

M. G. Broadhurst and G. T. Davis

October 24, 1979

The Structure and Transitions in Copolymers of Tetraf 1 uoroethyl ene

and Hexafl uoropropyl ene Polish Academy of Sciences, Lodz, Poland

R. K. Eby

October 24, 1979

Crystal Disorders in Copolymers of Tetraf 1 uoroethyl ene and Hexafl uoro- propylene

Institute of Polymer Chemistry, Zabrze, Poland

R. K. Eby

October 26, 1979

Elastic Modulus and Strength of Highly Drawn Polymers

Dutch Staatsmi jnen , Geelen, Holland

A. Peterlin

October 26, 1979

Non-Linear Viscoelastic Behavior of PMMA in Torsion

Bell Telephone Laboratories , Murray Hill, New Jersey

G. B. McKenna

October 26, 1979

A History of the Society of Rheology

Fiftieth Anniversary Meeting of the Society of Rheology, Boston,

Massachusetts

R. S. Marvin

October 29, 1979

Polymers as Piezoelectric Elements

Plastics Institute of America, Hoboken, New Jersey

M. G. Broadhurst

November 1 , 1 979

249
Statistical Mechanical Models of Polymers and Their Solutions

Massachusetts Institute of Technology, Cambridge, Massachusetts

I. C. Sanchez

November 7, 1979

Diffusion and Determination of Chain Structure in Polymers

Georgetown University, Washington, D.C.

L. E. Smith

November 7, 1979

Overview of Investigations in the Polymers Division on "The Structure

and Dielectric Properties of Polymer Tape Insulation for High Power

Transmission Cables"

Battel le Laboratories, Columbus, Ohio

F. A. Khoury

December 6, 1979

Phase Equilibrium Behavior of Polymer Blends

University of Akron, Akron, Ohio

I. C. Sanchez

December 6, 1979

Application of Solid State 13 C NMR in Semi crystal 1 i ne Polymers

Firestone Tire & Rubber Co., Akron, Ohio

D. L. VanderHart

December 20, 1979

Piezoelectric and Pyroelectric Properties of Polymers With Applicati ons International Business Machines, Binghamton, New York

M. G. Broadhurst

January 28, 1980

Piezoelectric and Pyroelectric Polymers--Mechani sms and Applications

University of Virginia, Chari ottsvi 1 1 e , Virginia

G. T. Davis

January 28, 1980

Concentration Dependence of Polymer Chain Dimensions

Johns Hopkins University, Baltimore, Maryland

D. J. Lohse

January 30, 1980

Phase Diagrams of Polymer Blends

Great Lakes Polymer Conference, Wayne State University, Detroit,

Michigan

I. C. Sanchez

February 14, 1980

Theory of Polymer Interfacial Tension

E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware

I. C. Sanchez

February 14, 1980

250
Molecular Weight and Temperature Dependence of Polymer Dimensions

and Intrinsic Viscosity

University of Massachusetts, Amherst, Massachusetts

C. C. Han

February 15, 1980

Statistical Mechanical Models of Polymers and Their Solutions

Michigan Molecular Institute, Midland, Michigan

I. C. Sanchez

February 15, 1980

Dependence of Chain Dimensions on Concentration

E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware

D. J. Lohse

February 18, 1980

The Development of Test Methods for the Environmental Stress-Crack

Resistance of Ethylene Plastics

ASTM Subcommittee D- 20 . 10. 14, San Diego, California

J. M. Crissman

February 19, 1980

Statistical Mechanical Models of Interacting Polymer Chains

NBS Colloquium on Mathematical Modeling in Science and Engineering,

Gaithersburg, Maryland

I. C. Sanchez

February 20, 1980

Diversity in the Lateral Growth Habits and Non-Planar Character of

Polyethylene Crystals

Bell Telephone Laboratories , Murray Hill, New Jersey

F. A. Khoury

February 21 , 1 980

Dependence of Polymer Chain Dimensions on Concentration

Hercules Corporation, Wilmington, Delaware

D. J. Lohse

February 21 , 1 980

Methods for Testing the Validity of Kinetic Models Using Data From

Varied Heating Rate and Jump Techniques

American Chemical Society, Seton Hall Univ. , South Orange, New Jersey

J. H. Flynn

February 25, 1980

Polymer Coil Instability in Laminar Flow

American Chemical Society, Carnegie-Mel 1 on University, Pittsburgh,

Pennsyl vani

a

A. Peterlin

February 28, 1980

251
Statistical Thermodynamics of Polymer Solutions

Johns Hopkins University, Baltimore, Maryland

I. C. Sanchez

March 5, 1980

13 C Linewidths in Solid Polymers Using High-Power Proton Decoupling

and Magic Angle Sample Spinning

21st Experimental NMR Conference, Tallahassee, Florida

D. L. VanderHart

March 17, 1980

Interfacial Tension Theory of Polymer Solutions

University of Washington, Seattle, Washington

I. C. Sanchez

March 18, 1980

Phase Diagrams of Polymer Alloys

Washington State University, Pullman, Washington

I. C. Sanchez

March 19, 1980

Piezoelectric and Pyroelectric Applications of Plastics

American Chemical Society, Houston, Texas

M. G. Broadhurst

March 24, 1980

Poling Behavior of PVDF

American Physical Society, New York, New York

M. G. Broadhurst and G. T. Davis

March 24, 1980

Piezo- and Pyroelectric Response From PVDF in Form III (y)

American Physical Society, New York, New York

G. T. Davis and M. G. Broadhurst

March 24, 1980

Non-Uniform Polarization and Space Charge in Ferroel ectri c Polymers

American Physical Society, New York, New York

A. S. DeReggi and M. G. Broadhurst

March 24, 1980

Temperature Dependence of the Pyroelectric Response and Thermal

Depoling of Vinylidene Fluoride Polymer

American Physical Society, New York, New York

A. S. DeReggi, G. T. Davis, and M. G. Broadhurst

March 24, 1980

Ferroel ectri c Polarization in Polymers

American Physical Society, New York, New York

M. G. Broadhurst and G. T. Davis

March 27, 1980

252
Acoustic Emission of Polymers During Crazing

American Physical Society, New York, New York

A. Peter! in

March 27, 1980

Overview of NBS and the Polymers Division

E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware

R. K. Eby

April 2, 1980

Dependence of Polymer Chain Dimensions on Concentration

Kansas State University, Manhattan, Kansas

D. J. Lohse

April 4, 1980

Statistical Mechanics of Polymer Solutions

Exxon Chemical Co., Linden, New Jersey

D. J. Lohse

April 8, 1980

Re-Evaluation of the Safety of Plastics

North Carolina State University, Raleigh, North Carolina

L. E. Smith

April 9, 1980

Mechanical Durability and Failure of Polymeric Materials

Free University, Amsterdam, Netherlands

G. B. McKenna

April 14, 1980

A Mean Field Theory of Polymer Solutions

Polytechnic Institute of New York, Brooklyn, New York

D. J. Lohse

April 15, 1980

Time Dependent Failure in PMMA and Polyethylene

University of Manchester Institute of Science and Technology,

Manchester, England

G. B. McKenna

April 16, 1980

Time Dependent Deformation and Failure Behavior of Poly(Methyl

Methacrylate) and Polyethylene

University of Leeds, Leeds, England

G. B. McKenna

April 17, 1980

Response of Carbon Black Filled Rubber to Cyclic Loading

Malaysian Rubber Products Research Association, Bri ckendonberry

,

Engl and

G. B. McKenna

April 18, 1980

253
Measurement of Dynamic Elastic Moduli

99th Acoustical Society, Atlanta, Georgia

S. Edelman

April 22, 1980

Piezoelectric and Pyroelectric Polymers: Mechanisms and Applications

Mechanics and Materials Colloquia, Rutgers University, New Brunswick,

New Jersey

G. T. Davis

April 24, 1980

Statistical Mechanics of Dilute and Semi -Dilute Polymer Solutions

Carnegie-Mel Ion University, Pittsburgh, Pennsylvania

I. C. Sanchez

May 2, 1980

Transport Phenomena in Drawn Semi crystal 1 i ne Polymers I Laboratory Technology of Polymers and Rheology, Naples, Italy

A. Peterlin

May 7, 1980

Cyclic Creep and Failure of Carbon Black Filled Rubber

IBM Research Laboratories , San Jose, California

G. B. McKenna

May 9, 1980

Transport Phenomena in Drawn Semi crystal 1 i ne Polymers II Laboratory Technology of Polymers and Rheology, Naples, Italy

A. Peterlin

May 12, 1980

Tensile Failure of Semi crystal 1 i ne Polymers

U.S. -Japan Meeting on Crazing, Flow, and Forming of Polymers, Rutgers

University, New Brunswick, New Jersey

A. Peterlin

May 21 , 1980

Perspectives on Resolution for 13 C NMR in Solid Hydrocarbons Using

Magic Angle Spinning

University of Delaware, Newark, Delaware

D. L. VanderHart

May 22, 1980

Research and the Saving of Teeth

Tokyo Medical and Dental University, Tokyo, Japan

G. C. Paffenbarger

May 30, 1980

Dental Alloy and Ceramic Compatibility

International Precious Metals Institute, Toronto, Canada

J. A. Tesk

June 2, 1980

254
The Accelerative and Adhesive Bonding Capabilities of Surface Active

Accel erators

International Association for Dental Research, Osaka, Japan

J. M. Antonucci

June 6, 1980

Derivatives of p-N,N-Dial kyl ami nophenyl al kanoic Acid:

tors for Dental Composites

International Association for Dental Research, Osaka,

G. M. Brauer

June 6, 1980

New Accel eraJapan

Ferroelectric Polarization in Polymers

International Symposium on the Statistical Mechanics of Phase Transi

tions in Polymers, Case Western Reserve University, Cleveland, Ohio

M. G. Broadhurst

June 13, 1980

Piezoelectric Polymer Research at NBS

Piezoelectric Polymer Workshop, Naval Research Laboratory, Orlando,

FI ori da

G. T. Davis

June 13, 1980

Research and the Saving of Teeth

Taiwan University of Dentistry, Taipei

G. C. Paffenbarger

June 13, 1980

Taiwan

Recent Developments With Piezoelectric Polymers

Polymer Chapter of the 3M Company Technical Forum, St. Paul,

Mi nnesota

M. G. Broadhurst

June 16, 1980

Enhancing Fluoride Incorporation into Enamel

School of Dentistry, National Taiwan University, Taipei, Taiwan

W. E. Brown

June 16, 1980

An Equilibrium Thermodynamic Approach is Taken to Describe the

Morphology and Stress Change During Crystallization or Melting

Gordon Research Conference on Polymer Physics, New London, New

Hampshi re W.-L. Wu

June 25, 1980

Lifetime Prediction of Polymer Stabilization

Institute of Polymer Science and Technology, University of New York,

New Paltz, New York

J. H. Flynn

June 27, 1980

255
High Resolution Solid State 13 C NMR of Semi crystal 1 i ne Polymers

Gordon Conference on Fiber Science, New London, New Hampshire

D. L. VanderHart

June 30, 1980

Methods for Testing the Validity of Kinetic Models Using Data From

Varied Heating Rate and Jump Techniques

Sixth International Conference on Thermal Analysis, Bayreuth, West

Germany

J. H. Flynn

July 8, 1980

High Resolution Solid State 13 C NMR Techniques for Studying Orientation and Molecular Motion in Polymers

Gordon Conference on Polymers, New London, New Hampshire

D. L. VanderHart

July 8, 1980

Non-Equilibrium Thermodynamics of Perfect Elastic Fluids

Seminar on Thermodynamic Inequalities, NBS, Gaithersburg, Maryland

E. A. Kearsley

July 17, 1980

Polarization and Molecular Hysteresis in Polyvi nyl idene Fluoride

Gordon Conference on Dielectric Phenomena, New London, New Hampshire

M. G. Broadhurst

July 19, 1980

Scanning Transmission Electron Microscopy of Polyethylene Crystals

Electron Microscopy Society of America, Reno, Nevada

F. A. Khoury

August 4, 1980

The Strai n-Energy Function for Rubber-Like Materials

IUTAM Symposium on Finite Elasticity, Lehigh University, Bethlehem,

Pennsyl vani

L. J. Zapas

August 11, 1 980

Polymers in the Future

American Society for Mechanical Engineers Emerging Technology

Conference

San Francisco, California

R. K. Eby

August 15, 1980

Equation of State Theories of Polymer Blends

International Symposium on Polymer Compatibility and Incompatibility,

Michigan Molecular Institute, Midland, Michigan

I. C. Sanchez

August 18, 1980

256
Spectral Resolution in Solid Hydrocarbons Using Magic Angle Sample

Spinning 13 C NMR

NATO Advanced Study Institute, Cagliari, Italy

D. L. VanderHart

September 3, 1980

Solid State 13 C NMR in Polymers

NATO Advanced Study Institute, Cagliari, Italy

D. L. VanderHart

September 4, 1980

Concentration Effect on Polymer Chain Dimensions

Joint U.S. -France Conference on Small Angle Scattering, Strasbourg,

France

C. C. Han

September 17, 1980

Piezoelectric Polymers

Office of Naval Research Meeting on Electroactive Polymers,

Washington, D.C.

M. G. Broadhurst

September 29, 1980

Technical and Professional Committee Participation and Leadership

American Association of Dental Research/International Association of

Dental Research

G. M. Brauer

Session Chairman

W. E. Brown

Member: Mineralized Tissue Group, Chairman

Biological Mineralization Award Committee

J. M. Cassel

Washington Section Delegate

American Chemical Society

G. M. Brauer

Member: Meetings and Expositions Committee

Special Events Committee, Chairman

American Dental Association Acceptance Program

J. A. Tesk

Member: Porcelain Metal Alloys

American Institute of Physics

R. K. Eby

Section Editor, 1 981 Physics Handbook

E. A. Kearsley

Member: Committee for Public Policy

257
American National Standards Institute

MD156: Dental Materials and Devices

J. A. Tesk, Chairman

Member: Base Metal Alloys

R. L. Bowen

Member: Toxicity Tests, Secretary

G. M. Brauer

Member: Denture Resins, Chairman

J. M. Cassel

Member: C054: Medical Devices Standards Management

Board

C092: US TAG for ISO/TC150, Implants for

Surgery, Chairman

N. W. Rupp

Member: Restorative Materials, Chairman

Alloy for Dental Amalgams, Chairman

Mercury for Amalgams, Chairman

Amalgamators for Dental Amalgams, Chairman

Dispensers for Mercury and Alloys for Dental

Amalgams, Chairman

American Physical Society

Division of High Polymer Physics

F. A. Khoury

Member: Executive Committee

Committee on History of DMPP

Committee on Short Courses

American Society for Testing and Materials

D02: Petroleum Products and Lubricants

L. J. Zapas

Member: D02.07: Flow Properties

D02.07A: Newtonian Viscometry

D09: Electrical Insulating Materials

W. P. Harris

Member: D09.05

D09. 12

D09. 16

D09. 17

D09.90

D09.93

D09.94

D09.95:

Ceramic Products

Electrical Tests

Hookup Wire Insulation

Thermal Capabilities

Executive Committee

Education, Research, and Symposia

Nomenclature, Significance, and

Stati sti cs

Li ai son

258
Dll: Rubber and Rubber-Like Materials

E. A. Kearsley

Member

G. B. McKenna

Member

D20: Plastics

R. K. Eby, Chairman

Member: D20.01: Executive Subcommittee

J. D. Barnes

Member: D20.12

D20. 19

D20.70

Olefin Plastics

Sheeti ng

Analytical Methods

WG.07: Gas Permeability

D. H. Reneker

Member

J. C. Smith

Member

H. L. Wagner

Member: D20.70: Analytical Methods

WG.04: Liquid Size Exclusion

Chromatography

WG.05: Molecular Weight

Parameters, Chairman

D27: Electrical Insulating Liquids and Gases

W. P. Harris

Member

E09: Fatigue

G. B. McKenna

Member

R. W. Penn

Member

E37: 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

E45: Geothermal Energy and Resources

E. A. Kearsley

Member: E45.02: Materials
F02: Flexible Barrier Materials

J. D. Barnes

Member: F02.30: Test Methods, Chairman

F02.93: Statistical Matters, Chairman

D. H. Reneker

Member

F04: Medical and Surgical Materials and Devices

G. M. Brauer

Member: F04.20: Resources

WG.01: Polymeric Materials,

Chai rman

J. M. Cassel

Member: F04.20: Resources

R. K. Eby

Member

G. B. McKenna

Member

Case Western Reserve University Materials Research Laboratory

Advisory Board

R. K. Eby

Member

Chemical Society of Washington

G. M. Brauer

Chairman, Membership Activities

International Confederation for Thermal Analysis

J. H. Flynn

Member: Nomenclature Committee

Working Party on Symbols

International Electrotechnical Commission

TC046: Cables, Wires and Waveguides for Telecommunication

Equipment

L. J. Zapas

Member: WG.03: Measuring Methods of Polyethylene

International Standards Organization

TC106: Dental Materials and Dveices

G. M. Brauer

Member: Task Force on Color Stability

N. W. Rupp

Member: Restorative Materials

260
National Bureau of Standards Advisory Panel for Tariffs on Electron

Microscopes Under Florence Agreement

F. A. Khoury

Member

National Center for Small Angle Scattering

Users Committee

C. C. Han

Member

National Research Council Panel on Polymer Science and Engineering

R. K. Eby

Member

North American Thermal Analysis Society

J. H. Flynn

Member: Executive Committee

Publications Committee, Chairman

Polymer Degradation and Stability (Journal)

J. H. Flynn

Editorial Board Member

Sixth International Conference on Thermal Analysis

J. H. Flynn

Session Chairman

Society of Plastics Engineers

G. B. McKenna

Member: Technical Publications Committee

Society of Rheology

E. A. Kearsley

Member: Executive Committee

G. B. McKenna

Member: Committee on Education

Local Arrangements 1981 Spring Meeting, Chairman

University of Massachusetts Advisory Board on Polymer Research

R. K. Eby

Member

261
Publ i cati ons

Optimizing Creep and Corrosion Properties in a Dispersant Amalgam

Using Manganese

R. M. Waterstrat

J. Dent. Res. , 57, 873 (1978)

New Initiator Systems for Dental Resins Based on Ascorbic Acid

J. M. Antonucci , C. L. Grams, and D. J. Termini

J. Dent. Res. , 58, 1887 (1979)

Compatibility of Various Materials With Oral Tissues.

I: The Components in Composite Restorations

R. L. Bowen

J. Dent. Res. Special Issue, 58, 1493 (1979)

New Amine Accelerators for Composite Restorative Resins

G. M. Brauer, D. M. Dulik, J. M. Antonucci, D. J. Termini, and

H. Argentar

J. Dent. Res. , 58, 1994 (1979)

Bonding of Acrylic Resins to Dentin With 2-Cyanoacrylate Esters

G. M. Brauer, J. A. Jackson, and D. J. Termini

J. Dent. Res. , 58, 1900 (1979)

Durability of the Bond Between Bone and Various 2-Cyanoacrylates

in an Aqueous Environment

G. M. Brauer, J. W. Kumpula, D. J. Termini, and K. M. Davidson

J. Biomed. Mater. Res., 13, 593 (1979)

Storage Stability of Dental Composites

G. M. Brauer, N. Petrianyk, and D. J. Termini

J. Dent. Res. , 58, 1791 (1979)

Polyvi nyl idene Fluoride Viewed as a Polycrystalline Ferroel ectri

Material

M. G. Broadhurst

Charge Storage , Charge Transport and Electrostatics Wi th Thei

Appl ications , Y. Wada, M. M. Perlman, and H. Kokado, Eds. , p. 143 (1979)

General Comments, Session V, Third International Symposium on Tooth

Enamel

W. E. Brown

J. Dent. Res. Special Issue B, p. 857 (1979)

Two Types of Pyroel ectri ci ty in a Copolymer of Vi nyl idene Fluoride

as Tetraf 1 uoroethyl ene

R. E. Collins, M. G. Broadhurst, G. T. Davis, and A. S. DeReggi

Charge Storage , Charge Transport , and Electrostatics Wi th Thei

Appl i cati ons , Y. Wada, M. M. Perlman, and H. Kokado, Eds., p. 170 (1979)

262
Performance of Plastic Packaging for Hazardous Materials Transportation, Part V, Mechanical Properties

J. M. Crissman, L. J. Zapas, and G. M. Martin

NBSIR 79-1938 (1979)

Physical and Chemical Properties and Wear

G. R. Dickson

J. Dent. Res. Special Issue, 58, 1535 (1979)

Fit of Porcelain Fused-to-Metal Crown and Bridge Castings

G. T. Eden, 0. M. Franklin, J. M. Powell, Y. Ohta, and G. Dickson

J. Dent. Res. , 58, 2360 (1979)

Electron Spin Resonance Spectra of Polymers During FI uori nation

R. E. Florin

J. Fluorine Chemistry, J_4, 253 (1979)

Molecular Weight and Temperature Dependence of Intrinsic Viscosity

of Polymer Solutions

C. C. Han

Polymer, 20, 1083 (1979)

Some Non-Linear Effects in Polymer Testing

E. A. Kearsley

Proceedings of ASTM Meeting on Geothermal Seals (1979)

Room Temperature Poling of Poly(Vi nyl idene Fluoride) With Deposited

Metal Electrodes

J. M. Kenney and S. C. Roth

J. Res. Nat. Bur. Stds. , 84, 447 (1979)

Simulation of the Relaxation of Random-Coil Polymer Chains by Lattice

Models With Excluded Volume: The Effect of Bead Movement Rules

D. E. Kranbuehl and P. H. Verdier

J. Chem. Phys. , 7±, 2622 (1979)

Raman Spectra of n-Alkanes: I. Raman Intensities of Longitudinal

Acoustic Modes

J. Mazur and B. Fanconi

J. Chem. Phys. , 71_, 5069 (1979)

Measurement of Polydi spersi ty of Narrow Fractions and Column

Spreading Parameters by Recycle Liquid Size Exclusion Chromatography

F. L. McCrackin and H. L. Wagner

Macromolecules, 21, 685 (1979)

Isoionic Isotope Exchange With Hydroxyl apatite and the Dilution

Effect

D. N. Misra

J. Res. Nat. Bur. Stds., 84, 395 (1979)

263
Reaction of Anthranilic Acid With Cupric Ion-Containing Hydroxyapatite

Surface

D. N. Misra and R. L. Bowen

Surface Contamination, Vol. 2, K. L. Mittal, Ed., Plenum Pub. Corp.

p. 983 (1979)

Fifty Years of Cooperative Research Between the American Dental

Association and the National Bureau of Standards, A Historical

Perspective 1928-1978

G. C. Paffenbarger

J. Dent. Res. Special Issue, 58, 1486 (1979)

Dental Materials

G. C. Paffenbarger and N. W. Rupp

Ki rk-Othmer : Encycl opedi a of Chemical Technology , Vol. 7,

3rd Edition

John Wiley & Sons, Inc. (1979)

Linear Dimensional Change of Copper-Rich Dental Amalgam

G. C. Paffenbarger , N. W. Rupp, and P. R. Patal

J. Amer. Dent. Assoc. , 99, 468 (1979)

Diffusion With Discontinuous Swelling. V. Type II Diffusion Into

Sheets and Spheres

A. Peterlin

J. Poly. Sci., Poly. Phys. Ed., 17, 1741 (1979)

The Lowest LASER-Raman Active Accordion (ALR) Type Oscillations

in Crystalline Polymers

A. Peterlin

J. Mater. Sci. , 14, 2994 (1979)

Transport Phenomena and Polymer Morphology

A. Peterlin

Makromol. Chera. Suppl., 3, 215 (1979)

Clinical Placement and Performance of Composite Resin Restorations

N. W. Rupp

J. Dent. Res. Special Issue, 58, 1551 (1979)

Phase Transition Behavior of the Isolated Polymer Chain

I. C. Sanchez

Macromolecules, J_2 , 980 (1979)

A Dynamic Mechanical Study of Phase Segregation in Toluene Di isocyanate Block Polyurethanes

G. A. Senich and W. J. MacKnight

Multi phase Polymers , S. L. Cooper and G. M. Estes, Eds., ACS Symposium

Series 176, p. 97 (1979)

264
A Dynamic Mechanical Study of the Curing Reaction of Two Epoxy

Resi ns

G. A. Senich, W. J. MacKnight, and N. S. Schneider

Poly. Eng. Sci. , 19, 313 (1979)

Models for the Migration of Additives in Polyolefins

L. E. Smith, I. C. Sanchez, S. S. Chang, F. L. McCrackin, and

G. A. Senich

NBSIR 79-1779 (1979)

Compatibility of Various Materials With Oral Tissues. II: Pulp

Responses to Composite Ingredients

H. R. Stanley, R. L. Bowen, and J. Folio

J. Dent. Res. Special Issue, 58, 1507 (1979)

Annealing Induced Changes in Orientation and Mobility in the Noncrystalline Region of Drawn Linear Polyethylene: A

13 C NMR Study

D. L. VanderHart

Macromolecules, 1_2, 1232 (1979)

13 C NMR Rotating Frame Relaxation in a Solid With Strongly Coupled

Protons: Polyethylene

D. L. VanderHart and A. N. Garroway

J. Chem. Phys. , 71_, 2773 (1979)

A Specification Method for Ultra High Molecular Weight Polyethylene

for Implant Use

H. L. Wagner and J. G. Dillon, Jr.

J. Bio. Mater. Res., 13, 821 (1979)

Nb-Si A15 Compounds Produced by Liquid Quenching

R. M. Waterstrat, F. Haenssler, and J. Muller

J. Appl . Phys. , 50, 4763 (1979)

Theory of the Instability and Failure of Viscoelastic Materials

in Tension

L. J. Zapas and B. D. Coleman

J. Poly. Sci., Poly. Phys. Ed., 17, 2215 (1979)

Measurement of Single Chain Neutron Scattering in Concentrated

Polymer Solutions

A. Z. Akcasu, G. C. Summerfield, S. N. Jahshan, Charles C. Han,

C. Y. Kim, and H. Yu

J. Poly. Sci., Poly. Phys. Ed., 18, 863 (1980)

Isocyanato Urethane Methacrylates Derived From Hydroxyethyl Methacryl ate

J. M. Antonucci , G. M. Brauer, and D. J. Termini

J. Dent. Res. , 59, 35 (1980)

265

l ilUUMU imnmwinriinmMMiiiiuiniii
A Theory of the Effects of Pressure on Finite Elastic Shear

B. Bernstein and E. A. Kearsley

Proceedings of the VIII International Congress on Rheology,

(in press) (1980)

Adhesive Bonding of Various Materials to Hard Tooth Tissues.

XXII. The Effects of a Cleanser, Mordant, and PolySAC on Adhesion

Between a Composite Resin and Dentin

R. L. Bowen

J. Dent. Res. , 59, 809 (1980)

Piezoelectric and Pyroelectric Properties

M. G. Broadhurst and G. T. Davis

Topics in Applied Physics, Vol. 33, Electrets (1980)

Piezoelectricity and Pyroelectricity in Poly(Vinyl idene Fluoride)

M. G. Broadhurst and G. T. Davis

NML 1979 Technical Highlights, p. 89 (1980)

Piezoelectric and Pyroelectric Applications of Plastics

M. G. Broadhurst, S. Edelman, and G. T. Davis

Organic Coatings and Plastics Chemistry, 42, 241 (1980)

Kinetics of Hydrolytic Aging of Polyester Urethane Elastomers

D. W. Brown, R. E. Lowry, and L. E. Smith

Macromolecules, 1_3, 248 (1980)

Diffraction From Nonperiodic Structures: The Molecular Conformation

of Polytetrafl uoroethyl ene (Phase II)

E. S. Clark, J. J. Weeks, and R. K. Eby

ACS Symposium Series on Diffraction Methods for Structural Determination

of Fibrous Polymers,

(in press) (1980)

Free Radicals and New End Groups Resulting From Chain Scission.

I. y-Irradiation of Polyethylene

K. L. DeVries, R. H. Smith, and B. M. Fanconi

Polymer, In Press (1980)

Investigation of Epitaxy Relationships Between Ca 5 (P0 4 ) 3 0H and

Other Calcium Ortho-Phosphates

B. Dickens

J. Res. Nat. Bur. Stds. , 54, 000 (1980)

User's Manual for Factor-Jump Thermogravimetry Apparatus and

Associated Computer Programs, Including a General Plotting Program

B. Dickens

NBSIR 80-2102 (1980)

High Resolution, Magic Angle Sample Spinning 13 C NMR of Solid

Cellulose I W. L. Earl and D. L. VanderHart

J. Am. Chem. Soc. , 102 , 3251 (1980)

266
Polymer Science and Standards

R. K. Eby

Dimensions, 64, No. 4 (1980)

Molecular Vibrations of Polymers

B. Fanconi

Ann. Rev. Phys. Chem. , 3J_ , 265 (1980)

Degradation Kinetics Applied to Lifetime Prediction of Polymers

J. H. Flynn

Poly. Eng. Sci. , 20, 675 (1980)

The Effect of Heating Rate Upon the Coupling of Complex Reactions.

I. Independent and Competitive Reactions

J. H. Flynn

Thermochim. Acta. , 37, 225 (1980)

Methods for Testing the Validity of Kinetic Models Using Data

From Varied Heating Rate and Jump Techniques

J. H. Flynn

Proceedings of the Sixth International Conference on Thermal

Analysi s

,

(in press) (1980)

The Niobium (Col umbi um)-Pal 1 adi urn Constitution Diagram

B. C. Giessen, N. J. Grant, D. P. Parker, R. C. Manuszewski , and

R. M. Waterstrat

Metal. Trans. A, TTA, 709 (1980)

The Effect of pH History on the Stability of Paper

E. L. Graminski and E. J. Parks

J. Res. Nat. Bur. Stds. , In Press (1980)

Use of Solid-State 13 C NMR in Structural Studies of Humic Acids

and Humin From Holocene Sediments

P. G. Hatcher, D. L. VanderHart, and W. L. Earl

Organic Geochemistry, 2, 87 (1980)

Determining an Elastic Strai n-Energy Function From Torsion and

Simple Extension

E. A. Kearsley

J. Appl . Phys., In Press (1980)

Some Methods of Measurement of an Elastic Strain Energy of the

Val ani s-Landel Type

E. A. Kearsley and L. J. Zapas

J. Rheology, In Press (1980)

Scanning Transmission Electron Microscopy of Polyethylene Crystals

F. Khoury and L. H. Bolz

38th Annual Proceedings Electron Microscopy Society of America,

p. 242 (1980)

267
Chain Distribution Functions and Segment Density Function of Polymer

Chains Confined by Absorbing or Reflecting Barriers

D. J. Lohse, R. J. Gaylord, and M. J. Paisner

J. Macromol ecul ar Sci. Phys. , B2Q , 000 (1980)

Measurement of Polydispersity of Narrow Fractions and Column Spreading

Parameters by Recycle Liquid Size Exclusion Chromatography

F. McCrackin and H. Wagner

Macromolecules, 1_3, 685 (1980)

Mechanical Properties of Some Fiber Reinforced Polymer Composites

as Fracture Fixation Plates

G. B. McKenna, G. W. Bradley, H. K. Dunn, and W. 0. Statton

Biomaterials, In Press (1980)

Mechanical Durability of Candidate Elastomers for Blood Pump Applicati ons

G. B. McKenna and R. W. Penn

Proceedings of the First World Biomaterials Congress,

(in press) (1980)

Time Dependent Failure in Poly(Methyl Methacrylate) and Polyethylene

G. B. McKenna and R. W. Penn

Polymer, 21_, 213 (1980)

Time Dependent Failure of a Polyolefin Rubber Candidate Material

for Blood Pump Applications

G. B. McKenna and R. W. Penn

J. Bio. Mater. Res., In Press (1980)

The Normal Stress Response in Non-Linear Viscoelastic Materials:

Some Experimental Findings

G. B. McKenna and L. J. Zapas

J. Rheology, In Press (1980)

Viscoelastic Behavior of Poly(Methyl Methacrylate): Prediction

of Extensional Response From Torsional Data

G. B. McKenna and L. J. Zapas

Proceedings of the VIII International Congress on Rheology, In Press

(1980)

Plasma Poling of Poly(Vi nyl idene Fluoride): Piezo- and Pyroelectric

Response

J. E. McKinney, G. T. Davis, and M. G. Broadhurst

J. Appl . Phys. , 51, 1676 (1980)

Important Accomplishments in Dentistry, 1930-1980: A Personal

Apprai sal

G. C. Paffenbarger

New York Journal of Dentistry, 50, 190 (1980)

268
Physical Testing of Polymers for Use in Circulatory Assist Devices

R. W. Penn, G. B. McKenna, and F. A. Khoury

NBSIR 80-2008 (1980)

An Empirical Relationship Between Hydrocarbon Polymers and its

Interpretation by Fraction Free Volume

A. Peterlin and F. McCrackin

J. Poly. Phys. , In Press (1980)

Diffusion With Discontinuous Swelling. IV. Type II Diffusion

Into Spherical Particles

A. Peterlin

Poly. Eng. Sci. , 20, 238 (1980)

The Transient of the Intrinsic Bi refri ngence and Light Scattering

of a Suspension of Rigid Spheroids in the Linear Laminar Jet Flow

A. Peterlin

J. Phys. Chem. , 84, 1650 (1980)

Performance of Plastic Packaging for Hazardous Materials Transportation, Part VI: Mass Loss and Effective Carbon Atom Number Measurement

J. C. Phillips

NBSIR, In Press (1980)

An Apparatus for the Infrared Measurement of Sorption/Desorption in

Strained Polymeric Films

J. C. Phillips and A. Peterlin

J. Poly. Sci., Poly. Phys. Ed., In Press (1980)

Non-Linear Behavior of Polyesobutyl ene Solutions as a Function of

Concentration

J. C. Phillips and L. J. Zapas

Trans. Rheology, In Press (1980)

Analysis of Mathematical Models of Integrating Monitoring Devices

R. J. Rubin

NBSIR 80-1975 (1980)

Energy Flow and Thermal Conductivity in One-Dimensional, Harmonic,

Isotopically Disordered Crystals

R. J. Rubin

M. S. Greem Memorial Volume, Perspectives in Statistical Mechanics,

(in press) (1980)

Effect of Residual Mercury Content on Creep in Dental Amalgams

N. W. Rupp, G. C. Paffenbarger , and P. R. Patel

J. Amer. Dent. Assoc., 1_00, 52 (1980)

Adhesive Bonding of Various Materials to Hard Tooth Tissues.

XX. Cal ci um-to-Cal ci urn Distances in Hydroxyapatite

L. W. Schroeder, R. L. Bowen, and J. S. Ferris

J. Bio. Mater. Res., 14, 83 (1980)
Fourier Transform Infrared Thermal Analysis of a Segmented Polyurethane

G. A. Senich and W. J. MacKnight

Macromolecules, J_3, 106 (1980)

Models for the Migration of Additives in Polyolefins

L. E. Smith, S. S. Chang, F. L. McCrackin, I. C. Sanchez, and

G. A. Senich

NBSIR 80-1999 (1980)

Phosphate Ion With Three "Symmetric" Hydrogen Bonds: The Structure

of Ca2 (NH 4 H 7 (P0 4 ) 4 -2H 2 0

S. Takagi , N. Mathew, and W. E. Brown

Acta Cryst. , B36, 766 (1980)

Mi rcoanalytical Techniques With Inverted Solid State Ion-Selective

Electrodes. I. Nanoliter Volumes

G. L. Vogel , L. C. Chow, and W. E. Brown

Anal. Chem. , 52, 375 (1980)

Microanalytical Techniques With Inverted Solid State Ion-Selective

Electrodes. II. Microliter Volumes

G. L. Vogel and W. E. Brown

Anal. Chem. , 52, 377 (1980)

Novel Cell for Light Scattering From Solutions

F. W. Wang and B. H. Zimm

Biopolymers, In Press (1980)

Order-Di sorder Transitions in Polytetraf 1 uoroethyl ene

J. J. Weeks, I. C. Sanchez, R. K. Eby, and C. I. Poser

Polymer, 21_, 325 (1980)

Internal Configurations of Span-Constrained Random Walks

G. H. Weiss and R. J. Rubin

J. Stat. Physics, 22, 97 (1980)

270
Division Seminars

Morphological Studies of Power Cable Insulation

Paul Phillips

University of Utah, Salt Lake City, Utah

September 10, 1979

Structure of Nafion Polymers

Michel Pineri

Centre d

1 Etudes Nucleaires, Grenoble, France

September 12, 1979

Polymeric Structures in Fibers of Polyterephthal ate Esters

I. H. Hall

University of Manchester, Manchester, England

September 13, 1979

Surface and Bulk Properties of Polymers by Inverse Gas Chromatography

Derek G. Gray

McGill University, Montreal, Canada

September 14, 1979

Dielectric Relaxations in Polymer Blends

William J. MacKnight

University of Massachusetts, Amherst, Massachusetts

September 28, 1979

Thermodynamics of Polymer Blend Compatibility

Frank Karasz

University of Massachusetts, Amherst, Massachusetts

October 5, 1979

Practical Application of the Thermal Pulsing Technique for Measuring

Charge Polarization Distributions in Insulators

R. E. Collins

New South Wales Institute of Technology, Sydney, Australia

October 18, 1979

Determination of DNA Molecular Weight by Viscoelasticity

Brian C. Bowen

Princeton University, Princeton, New Jersey

October 29, 1979

Electropolymerization on Graphite Fibers

T. S. Subramanian

Washington State University, Pullman, Washington

October 29, 1979

Charge Transport in Lossy Dielectrics

Andrew K. Jonscher

Chelsea College, University of London, London, England

November 6, 1979

271
Modeling Mechanical Behavior of Materials

Douglas MacDonald

National Bureau of Standards, Washington, D.C.

November 27, 1979

High Pressure Raman Spectroscopy of Ordered Liquid Phase of

n-Alkanes and Polyethylene

Stephanie L. Wunder

Naval Research Laboratory, Washington, D.C.

November 30, 1979

The Development and Uses of Hydroxyapatite as Scientific Substrates

and Potential Hard Tissue Implant Materials

Michael Jarcho

Carbomedics, Inc., San Diego, California

December 7, 1979

Ferroelectric Behaviors in the Copolymers of Vinylidene Fluoride

and Trif 1 uoroethyl ene Takeo Furukawa

Bell Telephone Laboratories, Murray Hill, New Jersey

December 10, 1979

Alkai Ion and Proton Conductivity in Alumina

Gregory C. Farrington

University of Pennsylvania, Philadelphia, Pennsylvania

December 12, 1979

Applications of Porous Metals to Skeletal Reconstruction

William Rostoker

University of Illinois, Chicago, Illinois

December 14, 1979

Weathering of Plastics

Field H. Winslow

Bell Telephone Laboratories , Murray Hill, New Jersey

December 14, 1979

The Crystal Structure of Polytetrafl uoroethyl ene ("Teflon")

(1) Low Temperature; (2) High Pressure

Edward S. Clark

University of Tennessee, Knoxville, Tennessee

December 19, 1979

Laser Beam Detection of Ultrasonic and Acoustic Emission Signals

B. B. Djordjevic

Johns Hopkins University, Baltimore, Maryland

December 19, 1979

272
Spacecraft Charging Investigation Studies of Polymer Response to

Kilovolt Charge Particles Fluxes

Carolyn K. Purvis

NASA-Lewis Research Center, Cleveland, Ohio

January 2, 1980

Biomedical Applications of Ion Thruster Technology

Bruce Banks

NASA-Lewis Research Center, Cleveland, Ohio

January 10, 1980

Structural Rearrangements in Constrained Macromolecules: Histones

and DNA in the Nucleosome

Henryk Eisenberg

Weizmann Institute of Science, Rehovoth, Israel

January 17, 1980

Photo-Oxidation of Polymers

Charles Rogers

Case Western Reserve University, Cleveland, Ohio

January 29, 1980

Current Status of Oral Implants, Emphasis on the Subperiosteal

Implant

Paul Mentag

Practicing Dentist, Southland, Michigan

February 1, 1980

Small Angle Neutron Scattering of Crystalline Polyethylene

Shi h- Jung Bai

University of Michigan, Ann Arbor, Michigan

February 7, 1980

Concepts in Polymer Processing

Costel Denson

University of Delaware, Newark, Delaware

February 7, 1980

Computer Studies of Model Polymers

Marvin Bishop

Fordham University, Manhattan, New York

February 19, 1980

Oscillatory Flow Birefringence of Dilute Polymer Solutions

Timothy P. Lodge

University of Wisconsin, Madison, Wisconsin

February 19, 1980

The Structure and Properties of Ultra High Modulus Polyolefins

Ian M. Ward

University of Leeds, Leeds, England

March 3, 1980

273
Polyoxymethyl ene Whiskers, Their Growth, Structure, and Properties

Masatoshi Iguchi

Research Institute for Polymers and Textiles, Tsukuba, Japan

March 5, 1980

Equilibrium and Non-Equilibrium Properties of Poly(01 ef i nsul fone)s

in Solution

Keizo Matsuo

Dartmouth College, Hanover, New Hampshire

March 5, 1980

Mechanical Properties and Fracture Behavior of Epoxies and Rubber

Toughened Epoxies

D. L. Hunston

Naval Research Laboratory, Washington, D.C.

March 19, 1980

Deuteron NMR in Solids and Solid Polymers

Hans W. Spiess

Johannes-Gutenberg University, Mainz, West Germany

March 26, 1980

Charge Transport in Plasma Polymerized Polysiloxane Films

Yvan Segui

University of Toulouse, Toulouse, France

March 28, 1980

Photo-Oxidation of Poly(Vinyl Chloride) and Acrylic Coatings

Christian Decker

Ecole Nationale Superieure de Chimie de Mulhouse, Mulhouse, France

March 31 , 1980

Recent Results in Spectroscopy of Disordered Polymers

G. Zerbi

Institute of Macromolecular Chemistry, Milan, Italy

April 4, 1980

The Status of Chain Folding: Report on the Cambridge Meeting

J. D. Hoffman, C. M. Guttman, and E. A. DiMarzio

National Bureau of Standards, Washington, D.C.

April 15, 1980

Raman Studies of Thin Polymer Films and Organic Monolayers by

Integrated Optical Technique

J. D. Swalen

IBM Research Laboratori es , San Jose, California

May 8, 1980

Improvements in an Underwater Acoustic Camera Using Polyvi nyl i dene

Fluoride Sensors

Lynn Holt and John McGrath

EMI, London, England

June 6, 1980

274
High Strength Polyethylene Filaments

Pieter J. Lemstra

Central Laboratory DSM, Geleen, Netherlands

June 11 , 1980

Investigation of Orientation and Crystallization Processes in

Polyethyl eneterephthal ate by Means of Different Methods Including

Synchrotron Radiation

Gerhard Zachmann

Institut fur Anorganische und Angewandte Chemie, Hamburg, West

Germany

June 17, 1980

NMR Magic Angle Spinning as a New Method for Investigation of

Permanent and Temporary Netpoints in Polymers

Gerhard Zachmann

Institut fur Anorganische und Angewandte Chemie, Hamburg, West

Germany

June 18, 1980

The Study of Textile Fibers With the Help of Paramagnetic Probes

Bernard Catoire

Institut Textile de France, Paris, France

June 20, 1980

Polymer Dynamics in Semi dilute Regions

Michel Delsanti

Laboratoire Leon Billouin, Yvette, France

June 30, 1980

Flow-Rate Dependent Degradation of High Molecular Weight Polymers in

GPC

Klaus Lederer

Institute for Chemistry and Physics, Leoben, Austria

July 3, 1980

Neutron Scattering Studies of Polyethylene

D. M. Sadler

University of Bristol, Bristol, England

July 9, 1980

China--A Nation Struggling to Recover From War

Charles Proffer Saylor

National Bureau of Standards, Washington, D.C.

July 9, 1980

Flow in Porous Membranes

F. W. Wiegel

Twente University, Enschede, Netherlands

July 17, 1980

275
Effects of Molecular Orientation in the Crystallization of Polymers

Andrzej Ziabicki

Polish Academy of Science, Warsaw, Poland

July 21 , 1980

Results of Fundamental Research on Interfacial Phenomena in Polymer

Blends

Werner Berger

Technische Universitat Dresden, Dresden, East Germany

July 21, 1980

Cationic Degradation of Hetero-Polymers

Eric Goethals

University of Ghent, Ghent, Belgium

July 22, 1980

Studies of Polymer Conformations in Solid Polymers by Small and

Wide Angle Neutron Scattering

Jakob Schelten

Institut fur Festkorperforschung , Julich, West Germany

August 13, 1980

External Recognition

Award of Appreciation

American Standards for Testing and Materials

October 1979

W. P. Harris

Charles Gordon Service Award

Washington Section

American Chemical Society

December 1979

G. M. Brauer

Silver Certificate

American Society for Metals

April 1980

J. A. Tesk

1980 Biological Mineralization Research Award

International Association of Dental Research

June 1980

W. E. Brown

Award of Appreciation

American Standards for Testing and Materials

June 1980

R. K. Eby

276
Honorary Member

Japanese Division

International Association of Dental Research

June 1980

G. C. Paffenbarger

1980 Mettler Award in Thermal Analysis

North American Thermal Analysis Society

July 1980

J. H. Flynn

Special Report

Organizations Engaged in Preparing Standards for Dental Materials

and Therapeutic Agents With a List of Standards

G. C. Paffenbarger , N. W. Rupp, and M. M. Malmstedt

NBS Special Publication 571 (1980)

Standard Reference Materials

Isoprene Isobutyl Butyl Rubber

Mooney Viscosity Standard 388(k)

G. B. McKenna and G. W. Bullman

November 1979

Patents

Acoustically Transparent Hydrophone Probe

A. S. DeReggi and G. R. Harris

Filed April 1980

ARC Furnace Modification for the Production of Small Investment

Casti ngs

R. M. Waterstrat

Filed August 1980

Workshops

Current Aspects of the Technology of Large Plastic Shipping Containers

Packaging Institute, National Bureau of Standards, Gaithersburg,

Maryl and

J. M. Crissman

September 1979

Interl aboratory Evaluations

American Standards for Testing and Materials, San Diego, California

J. D. Barnes

February 1980

277



METALLURGY DIVISION (564)

Robert Mehrabian, Chief

Anna C. Fraker, Deputy Chief

D. M. G. Summers, Secretary

The mission of the Metallurgy Division is to provide data, measurement

methods, standards and reference materials, concepts, 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 program of the Division involves studies of metals and alloys

in order to foster their safe, efficient, and economical utilization to

meet our national needs within the larger framework of the materials

cycle. Competences are developed and maintained in the general areas of

chemical metallurgy with special emphasis on phase diagrams and phase

stability; process metallurgy; quantitative microstructural character!’ zati on including nondestructive evaluation; 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,

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 to provide critically evaluated phase diagrams

to the metallurgical community. 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 of scarce or unavailable elemental constituents.

The detailed, programmatic content of the Division that follows is

described in the four general task areas:

12142,51105

12143

12144

12145

ALLOY STRUCTURE, PROPERTIES, AND STANDARDS FOR QUALITY

CONTROL, and SYNCHROTRON RADIATION RESEARCH FOR

MATERIALS SCIENCE

METALLURGICAL PROCESSING FOR ALLOY DURABILITY

ALLOY DURABILITY FOR WEAR APPLICATIONS

CHEMICAL METALLURGY FOR DURABILITY
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 materials are being produced for electron

microscope calibration, electron microprobe analysis, and electrical

conductivity. Contributions are made to NBS programs in nondestructive

evaluation, recycled oil and materials, and artificial implants.

Productive interactions with other groups at NBS exist in areas

such as surface analysis, wear, microstructural characterization, acoustic

emission, and phase diagrams. Computer graphics methods incorporating

phase diagram predictive techniques and thermodynamic data are being

developed in collaboration with the Applied Mathematics Division of the

National Engineering Laboratory.

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 Chairman of the B-6 Committee

and Post Chairman of Committee E-42, Vice Chairman of Committee G-2, and

Chairman of several subcommittees. The technical staff have organized

and chaired two international conferences on Rapid Solidification Processing,

an international conference on Implant Retrieval: Material and Biological

Analysis, and each year organizes and conducts two conferences on the

prevention of mechanical failures, and is organizing the 1981 International

Conference on Wear. The Metallurgy Division's staff serve on over sixty

other national professional and technical committees.

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 Project Agency, the Department of Energy, the

Naval Ship Research and Development Center, the U.S. Army Materials and

Mechanics Research Center, and the U.S. Army Mobility Equipment Research

and Development Command.

280
The available competences in the Division have recently been

strengthened and expanded by (1) a successful budget initiative in the area of metallic wear; (2) a new competence initiative within the National

Bureau of Standards to develop research programs at the Synchrotron

Light Source at Brookhaven National Laboratory with the main materials

expertise to reside within the Metallurgy Division; (3) the addition of

twelve new scientific staff members in the past twelve months; and (4)

the development of new programs aimed at promoting technical innovation

and improving our national productivity in the field of metals processing.

281

ALLOY STRUCTURE, PROPERTIES AND STANDARDS FOR QUALITY CONTROL

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 require a range of microstructural character!' zation and

nondestructive evaluation methods. The objectives of this task are to

address this challenge by 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, positron annihilation, acoustic emission, and ultrasonic methods.

A new competence program in Synchrotron Radiation was initiated

this past year (FY80) as a part of this task. The availability of

intense tunable well-collimated radiation at synchrotron radiation

facilities will permit radical gains in all areas of descriptive materials science, where the effects caused by the violation of translational invariance become increasingly important. As a joint NBS/NRL

effort, we aim to establish an x-ray instrumentation complex at the

National Synchrotron Light Source and to use it to perform frontier

experiments in transformations in materials, kinetics 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 Brookhaven and apply this to topographic analysis

of cracks in a stressed metal alloy and to glass-crystal metal alloy

transitions.

Other programmatic goals of this task are to evaluate quantitatively

acoustic emission in steels and aluminum alloys and compare with theory,

and to develop ultrasonic spectroscopy to the point that it can be used

in microstructure characterization and quality control for defects

during processing and use of structural alloys. Other efforts are aimed

at developing new nondestructive evaluation (NDE) methods such as positron

annihilation and in placing established techniques such as the magnetic

particle method on a more quantitative and reproducible basis. New

aluminum alloy eddy current standards were developed, calibrated, and

issued under this task. Finally, the NML-SEM facility is located in

this task. This facility not only serves various on-going research

efforts, but also is used in the development of Standard Reference

Materials for SEM.

The task is divided into subtasks whose activities and accomplishments over the past year are described next.

283
Synchrotron Radiation Research for Materials Science

Task 51105, and

Application of Synchrotron Radiation to Materials Science

Subtask 1 of Task 12142

M. Kuriyama, W. J. Boettinger, G. G. Cohen, R. D. Spal , H. E. Burdette

As the CMS part of the NBS program participating in the development

of research programs at the Brookhaven National Synchrotron Light Source

(NSLS), we have continued efforts on establishing beam lines on one of

the two ports assigned to NBS and the Naval Research Laboratory (NRL) on the storage ring at NSLS. The beam lines of our concern will use hard

radiation and will provide facilities for real time topography, small

angle scattering, interface spectroscopy, and crystal! ography. Hard

radiation down to as short as 0.5A will be produced from accelerated

orbiting electrons in a storage ring operated at 2.5 GeV. Synchrotron

radiation produces a spectrum of photons that is highly collimated, very

intense, continuous in energy, and linearly polarized. These unique

properties offer tremendous opportunities for advancing materials science

with the following three major advantages over laboratory x-ray sources:

(1) the approximately ten-fold increase in photon flux permits, for the

first time, real-time i_n situ studies on materials transformations , (2)

the tunability of available radiation for a desired energy permits

determination of the phases of crystallographic reflections, thereby

resolving important structural ambiguities. It also permits, via the

elemental tunability, the study of materials whose structure deviates

greatly from the periodicity locally, and (3) inelastic scattering could

be employed for the first time as a practical tool to study materials

properties and phase transitions via electronic properties of individual

atoms and molecules in condensed matter. Among many problems aiming at

the ultimate goal in materials science, which would be the formulation

and verification of discrete atomistic theory for rates of phase transformations and structure stability, we have placed an emphasis at the

initial phase on the development of dynamic i_n si tu measurement capability

to obtain an advanced knowledge in kinetics of mi crostructural transformations.

Under the new competence program started this past year (FY80), we

have added Dr. Gabriel le G. Cohen and Dr. Richard D. Spal to our permanent

professional staff. Also, Dr. Simon C. Moss, Professor of Physics,

University of Houston, and Dr. Robert E. Green, Professor and Chairman

of Materials Science Department, the Johns Hopkins University, have

joined our group as consultants. Also, we have started experiments at

NBS with Professor Haydn Chen, University of Illinois, Mr. Kee Chang

Yoo, Brown University, Mr. Allan Goldman, State University of New York

(Stony Brook) and Professor Ronald W. Armstrong, University of Maryland,

as guest workers. We have established close relations with Professor

Barton Roessler, Brown University, and Dean John Billelo, State University

of New York (Stony Brook) to perform experiments at NSLS. Through the

NSF international program, our group has established a cooperative

program of materials science with CNRS in France, which aims at the

collaboration of experiments using synchrotron radiation. This year as

284
a start, we participated as a U.S. representati ve in a U.S. -France

seminar on Applications of X-Ray Topography to Materials Science in

Paris, France, and assisted in establishing a policy between the U.S.

and French scientific activities in this area. We have been in close

contact with Professor H. J. Queisser and Dr. W. Hartmann, Max-Planck

Institut fur Festkorperforschung, Stuttgart, Germany, on the development

of real time imaging in x-ray topography.

We are now in possession of a 12 kw rotating anode x-ray generator.

This will assist us to develop many preliminary experiments before they

will be brought to NSLS and Cornell High Energy Synchrotron Source

(CHESS).

Technical activities can be summarized as follows. More detailed

descriptions of significant technical activities will be mentioned

separately after this summary.

Real Time Topography : A portable and completely remote-controll ed

topographic system has been constructed, based on the concepts of asymmetri

1 2

crystal topography and x-ray magnifiers . This prototype system was carried to the CHESS at Cornell University for a preliminary test. We

obtained an extremely parallel 1 arc/s) and wide (1.5 cm x 2.0 cm)

monochromatic (8.0 keV) beam. This experiment requires alignment of as many as five perfect Si crystals and a sample crystal. Using this beam, we obtained a topograph from a single crystal of nickel with oxide

deposits. Also, topographic images were recorded on a tape using an x-ray image intensifier video camera while the sample crystal was in

motion. This provides a preliminary test for the real time capability

of the system. Because of the extremely limited beam time available to

us, the relationship between the brightness of the diffracted beam and

the alignment of a collimating crystal has not been studied carefully.

However, our trip to CHESS was quite successful, particularly considering

the fact that this was the first wide beam multi crystal topography

experiment using synchrotron radiation.

Specifications of a sample chamber for fracture experiments have

been studied in collaboration with R. C. Dobbyn, Fracture and Deformation

Division.

Small Angle Scattering : The specifications of beam characteristics and

detector systems required for small angle scattering experiments for

polymers, metals, and alloys have been studied in close collaboration

with Drs. B. Dickens, F. A. Khoury, W. L. Wu, and G. T. Davis, Polymers

Division. New concepts have been developed to improve the angular

resolution (Aq) and the closeness of q=o. An experiment has just started

using ordinary laboratory x-ray sources to prove the validity of this

concept, as described in a separate abstract following this summary.

Interface Spectroscopy : A focusing tunable x-ray monochromator system

3 has been constructed for EXAFS experiments and fluorescence fine structure

experiments. This will be the prototype mechanism for a synchrotron

radiation beam line for measurements dealing with interface and surface

285
4 problems. Focusing elements and mini-detectors have been tested . Design specifications for sample environmental chambers have been studied

in collaboration with Dr. J. Kruger, Chemical Stability and Corrosion

Division, for oxidation problems.

We are now establishing direct contact with material scientists at

NRL in these three areas as well as in crystallography. Significant

achievements have been made in the characterization of hardness testing

in metals and the development of a new high-resolution x-ray diffractometer/

spectrometer, as described in the following separate abstracts.

Reflection X-Ray Topography of Hardness Indentations in

Copper and Nickel Single Crystals by K. C. Yoo, R. W. Armstrong, and M. Kuriyama

The plastic deformation zones surrounding microhardness indentations

put into the (110) surfaces of relatively soft copper and nickel single

crystals have been studied by the asymmetrical crystal topography (ACT)

method. The method gives valuable information about the importance of

workhardening to determining the level of the microhardness pressure and

to determining the magnitude of its anisotropy for different directions

of the indenter axes for Knoop or diamond pyramid indentations. This is

demonstrated especially for copper crystals by the very pronounced

appearance of the strain patterns for diffraction contrast obtained at

either type of hardness impression. Both the cumulative dislocation

displacements (for extinction contract) and their lattice rotations (for

misorientation contrast) are employed in the analysis of the topographic

strain patterns (see figure 1).

A New High-Resolution X-ray Pi f f ractometer/Spectrometer Using Asymmetric

Crystal

by Haydn Chen and Masao Kuriyama

We have developed an x-ray diffraction system which is capable of

producing and detecting x-rays with an angular resolution better than

two seconds of arc. This system utilizes a pair of asymmetrically cut

silicon single crystals in order to replace the conventional mechanical

slits as well as a twocircle single crystal goniometer needed for necessary

angular movements. These two crystals, having surface normals which

deviate from the [111] direction by 13.5°, can be arranged either in an energy dispersive configuration (figure 2a) which yields a high-resolution

(energy) spectrometer, or in a non-di spersi ve mode (figure 2b) which is

ideal for high-resolution (momentum) wide angle/small angle diffraction

work.

The diffraction principle responsible for this new development is

the fact that the exit beam divergence coming from an asymmetrically cut

crystal (ACC) is reduced from the rocking curve width of a symmetrically

cut crystal (uu s

) as represented by the following formula

A0 , = uj / m out s y

in which m (=si n0

Qu1

./si n©^ n = d ^./d. ) is the magnification (or asymmetry)

factor. Therefore, by using an ACC in its magnifying mode (i.e., m > 1),

286
(13 1 03 -t-J (13 3 O) 3 C

4-> OJ c. o 3 C •r— o r-o 3 (13 > 3 03 C

C

T3 03 -1—0 C 4- +J O +j •!-

•r— o 4— LO (U+Ji- 3 U 03 03 a (13 4- OJ r— •I- -f- o (13 -M O o £ 1.0 S. Ul

ra 0) 4-) 4- >, ^ v u_ sz r— O) 4-4- o s_ 1— (13 -O *0 -r- 3 ln 3 U 4J CTJ X 03 •r- 3 3 —

40

4->

O

O r— •(-

a

OL (13 s. s o 03 o ra •(- 4-3 3 r— "1“ JO 3 3

•r— r— -o >> a. c 3 s > 4- a o c. s

(a 4- •!— 03 >, TJ O) (13 C 034-1 03

OJ JO 4-> •>- o 3 <a <a

•t— +J 03 3 4J 3 4- >1 4- o -T- >,-a

•r* c 4-

O -C 4- J3 3 C o 3 a. 44 i

03 3 03 T3(—

fO 03 3 JO 3 T- 3 (13 s: cn c—

4 oa > u c 03 t— 3 • •r— c 03 0 3 " >3 • •r" 4-> •<— 03 3 o=

r— s_ 03 c • (a JO 3 d.

(13 3 3 4_

O O' <a

O) E 4- 03 4- 4-J •!— 3

4- O! 3 3 03 03O 03 3 c Q. 4-44 CO o

03 o CL 3. 3 3 O

U

•r— •r—

O 3 -r- JO t- 3 3

Li_ -M

u 4- Q.+-> 4J) 4J 4-) *

ii1* A

227
SLIT

X-RAY DISPERSIVE MODE

(a)

DETECTOR

X-RAY

NONDISPERSIVE MODE

(b)

®?ometrlcal arrangements a asymmetrically cut crystals: a) Ene^t disp e rsi ve configuration; b) NondisDei

u The crystal

S ?s

beam i- a 5

3 Way that the Tncomi

angled

S aCC8pred onl ^ W1'^in a very srr

283
we can, for a given wavelength, produce a parallel beam of x-rays with a theoretical angular divergence less than one sec of arc (e.g. , w

s =

6"

for Si (111) reflection, with m = 38 and Cu Ka radiation, A0

^ = 0.97").

At the detector end, we use another ACC in its demagni fyi ngmode (i.e.,

m < 1) such that a one second of arc acceptance angle is achieved. As a result, an extremely high-coll imation x-ray facility is obtained.

When the system is used in its non-dispersive configuration

(figure 2b), the measured line width diffracting off the second ACC under

a perfect alignment conditon should correspond to the exit beam divergence

from the first ACC or the acceptance angle of the second ACC, whichever

is larger. We have measured this line width and a value of 2.8 seconds

of arc (tilt) was obtained (figure 3). This observed value differs from

the theoretical value of 0.97 sec of arc mainly because we were unable

to manually adjust the goniometer arcs with sufficient precision. High

precision rotations are possible using, for example, piezoelectric

crystal tweakers and microstepping motors.

When a specimen is placed in between the two ACC's and the second

ACC is rotated with respect to the specimen, a high-resolution di ffractometer

is obtained. A diffractometer of this type can be used for (elastic)

small-angle scattering measurements. First, one has the angular resolution

of 2 seconds of arc of scattering angle, regardless of a small spread of

energy (e.g., Ka-, and Ka 2 )> correspond!' ng to Ak = 8 x 10 5 A

1

. Second,

one also can make measurements withi n the di rect beam at the extremely

close vicinity of the direct beam direction (6=0°), without being hindered

by the direct beam. This is possible, because the second ACC, acting as an ideal receiving slit, only receives photons coming within 2 seconds

of arc of the desired scattering angle, even though the direct beam (0 =

0°) strikes the second ACC completely. The smallest k (=4nsin0/A) that

one can reach with this facility i s 8 x 1 0

5 A1 usi ng Cu K radiation.

This unique feature of defining a scattering angle regardless of photon

energies enables one to circumvent the measurement difficulty associated

with the blurring and overlapping effect in scattering patterns due to,

say, individual polymer grains normally created by the finite (relatively

large) size of mechanical slits in small angle scattering experiments.

This system can also be used for wide-angle diffraction studies necessitating

high angular resolution and the advantageous feature of parallel beams.

Some examples in this category are residual stress measurements free of

sample position effect, fine splitting of Bragg peak during phase transformation, thermal diffuse scattering in the vicinity of Bragg reflection,

corrosion and oxidation on single crystal surfaces, etc.

One of the main concerns of this double crystal arrangement is the

lack of photon flux. We, however, have measured the reflectivity of the

second ACC with respect to the first ACC. A nearly perfect total reflectivity, better than 95 percent, was confirmed. This fact guarantees the

highest flux consistent with the resolution obtained for the use of

multiple ACC arrangements.
CfTV) A1ISN31NI

coQ2O

UJ

CO

ofI CD3 0)

0)u

-o 3 c 3 o -a O T-

_ <u > — </i a> (O' a

O) 00 "Z’ .-3 3

oo +> "O >,o

-3 o<

-a

<d o 3 2

•r- +->

.-a +> <+- -3 O O

-M E 3 3 0J S- E

4_j 0) u cn

a> c

a. ro

CO ss_ < 3

0) • >

CO •<-oo

<u iS_ 0) 31 oo" o > 3 3

•T- S- ol, +J — ~ I <oO 3

s_ s- >1 o 3 0)r

a.

a

oi

—1 U oo C oO >

<3 -3

-P H- 35c

00 >1 - 3 i— S' 3 c 01

2-3-1

"3 ul

U

fjl

2S0
References

(1) W.Jr.

J. Boettinger, H.

, Rev. Sci. Inst.

E. Burdette, M. Kuriyama, and

47 906911 (1976).

R. E. Green,

(2) W.50

J. Boettinger, H. 2630 (1979).E. Burdette, and M. Kuriyama, Rev. Sci. Inst.

(3) G.Sci

G. Cohen, D. A. Fischer, J. Colbert, and N. J.

. Inst. 51 273277 (1980).

Shevchi k, Rev.

(4) D. A. Fischer, G. G. Cohen, and N. J. Shevchik, J. Phys. F: Metal

Physics 20 L139L142 (1980).

X-ray Residual Stress Evaluation in the Interior of Industrial Materials

Subtask 2 of Task 12142

M. Kuriyama, W. J. Boettinger, C. J. Bechtoldt

This project is part of the Metallurgy Division's participation in

the NBS NDE Program. The objective is to develop a nondestructive

method of mapping the distribution of residual stresses within industrial

materials of considerable thickness. This has been carried out in

collaboration with Robert Placious, Radiation Physics Division, Center

for Radiation Research.

One of the nondestructive methods currently used for measurements

of residual stresses in industrial materials involves the application of

x-ray analysis for stress measurement. X-ray diffraction phenomena are used to determine macroscopic residual stresses in engineering components.

The methodology of analysis and its basic principles are well known.

Briefly, when materials are under stress, x-rays are diffracted with a Bragg angle which is slightly different from the Bragg angle expected in

unstressed materials. The change in the Bragg angle is related to the

alteration of atomic interplanar spacings when the crystal lattice of

the materials is strained. As a measurement system, the essential part

of this x-ray technique is the accurate measurement of lattice constants

(or their changes) in materials by use of well-refined Bragg di f f ractometry

.

The surface residual stress can be evaluated from the strains measured

by x-ray di ffractometry using a set of assumptions regarding material

elasticity and homogeneity. Although the accuracy obtained by this

technique is, in principle, superior to any other method, an obvious

shortcoming lies in its incapability of detecting strains (or stresses)

in the interior of bulk materials.

Improved quality control of industrial materials and early detection

of flaws in these components require quantitative information concerning

the stress distribution near cracks and residual stress distributions

after different types of cold working and heat treating or under various

conditions of load. These demands naturally lead to the necessity of

measuring residual strains i_n the i nteri or of materials. Among many

nondestructive techniques for the measurement of residual stresses, the

x-ray diffraction technique, called Bragg di ffractometry , excels in its

291
accuracy. Yet this technique is incapable of detecting stresses in the

interior of bulk materials. Last year we proved^ that the desired

resolution and detectability was possible if the energy dispersive

diffraction method was employed with good x-ray optical conditions,

using ordinary laboratory x-ray sources and thin materials. This year,

we have used an industrial radiographic x-ray source with radiation up

to 200 keV and commercial steel and aluminum plates up to 1 cm and 3 cm thick, respectively, to test if the methodology previously established

is feasible outside the laboratory.

More than two years ago, we proposed^ an entirely different approach

to the x-ray evaluation of residual strains (or stresses) although it uses the principles of x-ray diffraction. This approach uses energy

dispersive spectroscopy, where an energy dispersive solid state detector

is employed within a wel 1-coll imated high energy beam of photons. Last

2

year (NDE Annual Report 1979, p. 66) we proved using ordinary laboratory

x-ray sources and thin materials, that the desired resolution and detectability can be achieved for the determination of residual stresses if

this technique is employed simultaneously with the curve fitting technique.

The objective of this year's activity is to demonstrate this capability

using an industrial radiographic x-ray source with radiation up to 200 keV

and commercial steel and aluminum plates up to 1 cm (or a half inch)

and 3 cm (or one and one-half inch) thick, respectively. If the feasibility of this technique is proved for use outside the laboratory, the

mapping of a residual stress distribution inside an industrial material

can be performed with relative ease on site.

To achieve this methodology, the following three major principles

are involved:

(a) Well-defined diffraction energy peaks should be obtained at an energy range of about 100 keV. These high energy photons can penetrate

through a quite thick material, so that the diffraction peaks obtained

by these high energy photons guarantee to deliver the stress information

within a bulk material.

(b) These diffraction energy peaks should have a Gaussian profile so that the curve fitting technique can be used for the determination of

the centroid (or peak) positions.

(c) The measurement accuracy of lattice constants or their variations

(hence, residual stresses) should be increased by a factor of 100,

compared with the resolution limit of solid state detectors, by use of curve fitting. The relationship between the improvement factor (that

is, the accuracy of determined strains) and counting statistics should

be investigated.

All of these principles have been confirmed with thin materials

using low energy photons. The use of high energy photons creates scattering

problems and background problems which directly affect the accuracy of our measurements. We have succeeded in controlling these problems. The

results are shown in the following.

292
(a) As shown in figure 1, diffraction energy peaks are clearly

separated with significant intensities. This spectrum was obtained from

a commercial steel plate (AISIC1015SAE1015) 3/8 inch thick. In this

case, the scattering angle was set at 2 0 = 5.7° with the incident

divergence 3 m rad (0.17° = 10 min) and the receiving divergence much

less than 3 m rad, so that the diffraction peaks can be obtained through

the entire thickness of the sample at a given point of the sample surface.

The spatial size of the beam on the sample is less than 1.5 x 1.5 mm2

. The diffraction peaks are indexed as shown in figure 1. Note that the

well-defined (211), (220), and (310) appears in the energy range between

90 kev and 150 kev in this transmission geometry. This result indicates

that the previously mentioned principle (a) is completely satisfied.

(b) Figure 2 shows an example of the observed spectral profile, say

(110), which has been fitted by a Gaussian curve with a linear background.

A perfect Gaussian fitting demonstrated here certainly indicates a great

promise in the precision determination of centroid (or peak) positions

for each observed energy peak. Hence, principle (b) has also been

confirmed experimentally for high energy photons.

(c) We are now in the process of proving principle (c). And further,

efforts are being made to increase the scattering angle without loss of

resultant intensities in peaks, so that one can really determine stresses

within small volumes inside materials.

References

(1) M. Kuriyama, W. J. Boettinger, and H. E. Burdette, ASNT National

Fall Conference, October 1979, Denver, CO, p. 49 (1978).

(2) M. Kuriyama, W. J. Boettinger, H. E. Burdette, Proceeding of Symposium

on Accuracy in Powder Diffraction, NBS Special Publ. 567, p. 579

(1980).

Acoustic Emission for NDE

Subtask 3 of Task 12142

J. A. Simmons, R. B. Clough

Acoustic emission (AE) is a relatively new nondestructive testing

technique relying on the detection of stress waves emitted during the

motion of flaws or from other mi crostructural changes in a highly stressed

region of a structure. This technique has been applied to aerospace,

petrochemical, bridge, and power plant structures to monitor structural

integrity. It has also been used to detect faulty welds in production

lines. In addition, AE has been used for materials research studies on microstructure related properties such as deformation mechanisms, phase

transformations, and fracture.

Highlights in the AE area in the Metallurgy Division during the

past year are (1) development of indentation techniques for the experimental

production of AE signals from material defects; (2) experiment design for

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multichannel AE source characterization; (3) progress on acoustic emission

theory and signal processing techniques; and (4) guest workers and interlaboratory collaboration with AERE, Harwell.

(1) Indentation techniques have been highly developed for use with

ceramics materials for studying crack growth under controlled loading.

We have therefore begun to adapt the technique to use with metals as a new type of controllable acoustic emission source. Besides the control

possible on the growth of defects, this method also ensures that the source location is fixed, an essential feature for AE signal analysis

and microstructure correlation. Such a technique provides, under the

proper conditions, a means of generating reproducible AE signals from

known types of sources having predictable signatures. This allows one

to actively control AE and thus constitutes an advance in the technique

from its present mode of merely passive listening.

We have been developing the indentation method in metals and alloys

so far using three new types of methods: (a) indentation brittle fracture;

(b) indentation fatigue; and (c) indentation stress corrosion cracking.

The brittle fracture method has been successful on steels which

have been hardened by heat treatment. It has been found that if the

surface is hardened to greater than 45 ± 5 on the Rockwell C scale,

indentation by a diamond pyramid will produce subsurface penny-shaped

median plane cracks generally less than a millometer in size. By controlled

loading it is possible to produce identical repetitive signatures,

typically on the order of 10 but sometimes over 100. Comparison with

SEM micrographs suggests that these signals are produced by incremental

crack growth along carbides and martensitic platelets. This idea has

been exploited in the design of a portable "acoustic embrittlement

detector" which can detect locally embrittled areas of structures such

as in the heat affected zones of welds or on critically stressed areas.

This technique has also been studied as a means of producing localized

fatigue cracks in 2024 and 7075 aluminum where, after sufficient load

cycling, reproducible signals are emitted. Comparison of AE signals and

SEM micrographs shows characteristic differences in signals in these

alloys which are explainable in terms of the defect microstructure.

Finally, fatigue cracks can be generated and after removal of the indentor

a drop of corrosive medium is placed over the indentation. The residual

stress is sufficient to generate numerous stress corrosion signals which

are also being studied in relation to microstructure.

Interactive experiments with Dr. Wadley of AERE, Harwell, have also

begun using a plate indented with a bias stress to give further control

on the defect morphology. There are in fact a number of interesting

experiments suggested by this newly available research tool which cannot

be summarized now but appear quite fruitful.

(2) A high speed interface has been designed and is being constructed

for monitoring up to 16 AE channels using 20 MHA transient A to D recorders

with variable timescale for synchronization, up to 100 dB dynamic range,

and less than 100 millisecond dead time to dump all channels. This
interface will be connected to our new microcomputer and will be operated

remotely in the laboratory under computer control. Monitoring of experimental

parameters will also be under computer control. A loading machine

capable of producing bias stresses in large metal plates is being designed

to permit creating defects under variable but controlled conditions.

This instrumentation will permit us to simultaneously monitor at several

transducer sites AE from defect sources produced on a plate by indentation

or other directed energy loading. Using the theory developed at NBS we

will then be able to calculate the stress drop history characterizing

the source. Knowledge of the stress drop history gives information on the defect orientation and geometry, then dynamics of the emission

process, and the local stress conditions. This information will be used

interactively with metallurgical examination and defect mechanism modeling

to enhance our understanding of defect dynamics and to develop critical

AE indicators to signal critical feature events.

(3) The theory of acoustic emission from defect sources has been

extended to include inhomogeneities such as martensitic transformations

and microcracks. In addition, an extensive series of computations of

waveforms to be expected in steel and glass plates have been carried

out. These calculations have graphically demonstrated the great directionality of acoustic emission signals as well as pointing the potential

new signal processing techniques. The plute code is currently under

revision to allow more accurate Fourier transforms of the plate solutions

to be computed, thus permitting more reliable inversion methods. Finally,

the theory of noise propagation has been carefully studied using quadroutic

noise statistics and criteria have been developed for optimal noise

filtering to use in conjunction with deconvolution techniques.

(4) Dr. M. Rosen of Technion, Israel, will be with us for the near

future, opening a new series of AE studies. Dr. Rosen's knowledge of

materials science will add considerable breadth to our program and will

provide additional opportunities to make use of the quantitative AE

techniques we are developing.

Dr. Haydn Wadley of AERE, Harwell, has also joined the Metallurgy

Division as a guest worker for one year with the Structure Characterization

Group. He will work primarily on acoustic emission studies of materials

in our Division. Dr. Wadley is well known in the acoustic emission

community for his innovative experimental studies of materials by quantitative

acoustic emission.

Dr. Wadley is joined with Dr. James E. Sinclair of Harwell for

three months who will be helping to implement the plate theory in AE

signal analysis.

These visits have resulted from informal cooperation between the

Harwell group and the NDE program at NBS. Both groups are working on the development of a new type of acoustic emission methodology which

will permit reconstruction of the emission source. To achieve this, a series of critical experiments will be performed using the combined

expertise of both groups. If successful, the new multichannel method

297
will provide information unobtainable by other known methods on crack

growth, metallurgical phase changes, and other dynamic materials effects.

Besides basic materials studies, the method has great potential for

quality control in industrial processes such as welding and for in-service

surveillance of aircraft structures and nuclear pressure vessels.

The first phase of the NBS/EPRI AE program has been completed and

an extensive two volume report has been submitted. ASTM interaction

continues strongly with the Vice-Chairman of ASTM Subcommittee E7.04

coming from this Division.

There has been substantial interaction with the NDE community,

particularly in the nuclear industry, with one of our members having

been Session Chairman, a member of the Organizing Committee, and who now

has been selected to be the General Chairman of the Fifth International

Conference on NDE in the Nuclear Industry, to be held in 1982 and sponsored

by ASM, ASNT, and ANS.

Ultrasonic Materials Characterization

Subtask 4 of Task 12142

R. Mehrabian, S. Fick, R. B. Clough, J. A. Simmons

This is a new activity using ultrasonic techniques for nondestructively

measuring microstructural material parameters. Ultrasonics as commonly

used in pulse echo or imaging systems detects macroscopic discontinuities

such as flaws or interfaces in material structures. However, the measurement

of ultrasonic attenuation and velocity changes or the study of the

absorption and transmission spectra of scattered ultrasonic waves provides

a wealth of detail on the mean microstructural properties of metallic

materials. These techniques have great potential for measuring texture,

porosity, and multiphase distributions, as well as for studying the

kinetics of phase transformations both by observing and inducing such

transformations.

Work in cooperation with Prof. R. Green of Johns Hopkins University

has been initiated on ultrasonic characteri zation for "soft spots" in

aluminum alloys. Detailed description of the overall program in this area is given under subtask 3 of Task 12145. The first priority of the

effort in this task is to develop a reliable alternate NDE method for

detection of these "soft spots." Velocity, attenuation, and ultrasonic

scattering techniques are being employed and their reliability assessed.

Longer-term studies are contemplated of the kinetics of the aging process

itself leading to better specifications for such alloys in the future.

Currently, the relative merits of various developmental techniques

for measuring ultrasonic attenuation and velocity are being experimentally

investigated. Since ultrasonic parameters are extremely sensitive to

measurement techniques, considerable effort has been devoted to the

optimization of procedural and equipment design. Methodologies under

investigation include the use of test fixtures incorporating design

features allowing transducer-to-specimen alignment independent of dimensional

variations in the specimen. Test fixtures employing long path and direct

298
transducer-to-specimen contact in liquid coupling media have been designed

and constructed. Transducers capable of high efficiency operation at

the high frequencies necessary for adequate sensitivity to precipitate

development in a selected alloy have been designed and fabricated. The

use of conventional transducer designs at higher than normal frequencies

has also been investigated. Results obtained thus far indicate that

further developmental effort is necessary and justified. Longer-term

studies are contemplated of the kinetics of the aging process itself

leading to better specifications for such alloys in the future.

Doppler-Broadened Positron Annihilation Lineshape for Detection of Defects

in Materials

Subtask 5 of Task 12142

R. C. Reno, L. J. Swartzendruber

Positrons that annihilate in a metal produce gamma rays whose

energy distributions can be explained in terms of a Doppler shift caused

by motion of electrons. When defects are present in the metal, they

attract and trap positrons, and alter the Doppler shifts. A measurement

of doppler-broadened annihilation lineshapes thus gives information on the defect nature of materials. Both the annihilation process and the

method of detection leave the sample intact, so the technique is extremely

useful for the nondestructive evaluation of materials.

Doppler-broadened lineshape measurements are performed by placing a positron source in contact with the sample to be studied (see figure 1).

Positrons enter the sample, slow down to thermal energies, and then

annihilate with electrons. Each annihilation produces two gamma rays

with a total energy equal to the rest mass energy of the positron-electron

pair (1022 keV). The distribution of energy between the two gamma rays

depends upon the electronic and defect structure of the sample, and is

measured with a high resolution solid state detector-multichannel analyser

system. A lineshape parameter, S, is defined which is a measure of the

inverse width of the distribution.

The addition of a small number of defects to a metal will cause a significant change in the lineshape parameter, and it is this sensitivity

that is used to observe changes in defect concentration and type. We

have used this technique to study defects in cold worked titanium and, more recently, have begun to study precipitation hardening in aluminum

alloys. In the latter study, some results of which are shown in figure 2, we observe significant changes in S parameter as microprecipiates form

during aging.

Magnetic Measurements

Subtask 6 of Task 12142

L. Swartzendruber

One of the most extensively used techniques in magnetic NDE is the

magnetic particle method. The application of this method is currently

guided by empirical rules for the amount of magnetization required to
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independently testing magnetic inks. The first steps in placing magnetic

particle inspection on a more quantitative and reproducible basis are an understanding of how the leakage field from a defect is influenced by

the defect geometry and level of magnetization reached by the material,

and a detailed description of the influence of the leakage field on the

formation of an indication by the magentic ink.

We have previously investigated the leakage fields from a steel

ring with artificial defects introduced by drilling a series of small

holes at varying depths below the sample surface. The ring geometry

used was the same as specified in MIL-E-6868E and in the new ASTM recommended

practice for magnetic particle inspection. It was found that all residual

and active leakage fields could be closely approximated using a linear

dipole model provided that an apparent depth, less than the actual depth

of the defect below the surface, and an equivalent dipole strength,

greater than that predicted by the linear theory, were used. One of the

disadvantages of the ring geometry was that the magnetization level

actually achieved in the steel ring varied with the defect depth and

could not be monitored. It was also found that the artificial defects

specified for the ring were too close together in that the leakage field

from one defect was distorted by its neighboring defects.

To overcome these difficulties a sample containing artificial

defects with the geometry shown in figure 1 was constructed. Using the

pickup coil shown, the level of magnetization in the material can be

monitored while the leakage fields from the artificial defects are being

measured. A Hall effect probe was used to measure the tangential and

perpendicular components of the leakage field at five different points

on the hysterisis curve of the sample. These leakage fields were least

squares fitted to a linear dipole model. Typical data and fits are illustrated in figure 2. As for the case of the ring geometry, it was found that the residual and active leakage fields could be closely

approximated using a linear dipole model with an apparent depth and an equivalent dipole strength. Both the equivalent depths and the equivalent

dipole strengths were roughly the same as those found for the tool steel

ring. An interesting feature of the results on the sample of figure 1 is that the magnitude of the leakage field increases almost linearly

with the applied magnetic field even after the material is driven into

saturation. Further studies are planned on other defect geometries

including very narrow cracks and slots of various depths in a sample

similar to that of figure 1. Using these results it should be possible

to devise more valid tests for the quality of magnetic inks and to

specify more precisely the level of magnetization required to detect

defects of a given geometry.

Eddy Current Standards

Subtask 7 of Task 12142

L. H. Bennett, J. R. Cuthill, L. J. Swartzendruber

The specifications for a set of aluminum conductivity standards were established. Four alloys were chosen to cover the conductivity

range of 30 to 60 percent IACS; 2024-T351 for a standard with nominal

302
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are data points and the dashed line is a least squares fit to a linear dipole model.

303
conductivity of 30 percent IACS, 6061-T6 for a standard with nominal

conductivity 40 percent IACS, 2024-0 for a standard with nominal conductivity 50 percent IACS, and i 1 00- F for a standard with a nominal conductivity of 60 percent IACS. These alloys are to be milled into coupons

44.5mm x 44.5 mm x 9.5 mm from a plate 12.7 mm thick. The surface

finish on both sides is specified to be better than 1 pm RMS and each

alloy is to be anodized in a distinctive color. A set of 100 of each of

these standards has been ordered and received and turned over to the

Electrical Measurements and Standards Division for calibration. Work

has been initiated on finding a suitable alloy and specifications to

cover conductivity standards in the range of 1 percent IACS which are required for use with titanium alloys, and to determine what standards

would be desirable for use with eddy current measurements on steel.

Scanning Electron Microscope

Subtask 8 of Task 12142

D. B. Ballard

The NML-SEM facility consisting of two scanning electron microscopes

(SEM) and associated equipment have provided over 1,200 hours support to

other research activities at NBS. Two approaches are used; one is the

particular scientist operates the SEM in the examination of his samples.

The other arrangement is that the SEM services and analyses are provided

by the SEM laboratory. Some examples are as follows.

Discovery by an outside aircraft manufacturer of very low tensile

strength aluminum alloy thick plate stock produced by Reynolds Metals

initiated a request by NASA that NBS review the relationships between

NDE, mechanical properties, and microstructures. Detailed description

of the overall program in this area is given in subtask 3 of Task 12145.

A series of SEM photomicrographs taken in the magnification range of 50

to 5,000 X of sections from as-cast ingots and subsequent different heat

treatments showed macrosegregation, recrystall ization, grain growth,

formation of inclusions, and precipitation of "0" phase. This information

was complemented with optical and TEM microscopy to illustrate the

effect of fabrication process variables on microstructure.

Part of the Recycled Oil Program includes the characterization

analysis of mechanical wear tests. Twenty-one sets of 52100 steel ring-andblock combinations tested at different loads with different ASTM lubricants

have been examined with the SEM for wear scar surface topography.

Studies of entrance, center, and exit areas are being correlated with

data of friction and temperature data in an effort to develop understanding

of wear mechanisms involved. The goal is to develop a data base of wear

observations on mechanical parts for evaluation of lubrication systems

usi ng reref i ned oi 1

Work on three different SRM's concerned with the SEM was conducted.

One was the production of 150 units of Resolution Test Sample SRM-469,

formerly designated RM-100 Aluminum-Tungsten dendrites. This sample is one of four available; however, it can be used from magnifications of

304
2,000 X to 100,000 X. The second activity was the accurate measurement

of four crack widths that varied from 0.2 to 2p on a prototype SRM to be

issued for the evaluation and calibration of crack detection using the

NDE method of liquid penetrant or visual optical techniques. This

measurement technique was made possible by use of SRM-484 (Magnification

Calibration of Sample for the SEM). The number of SRM-484 units sold to

date is 346. An additional 100 units have been calibrated and will be

available for issue. Thus far it is the only sample that has traceability

to NBS national standards.

Draft #5 of the "Standard Practice for Calibrating the Magnification

of an SEM Using NBS-SRM-484" has been approved by E-4 of the ASTM.

Final approval by the ASTM Society is expected in 1981.

305
1
METALLURGICAL PROCESSING FOR ALLOY DURABILITY

Task 12143

Metals processing research plays a central role in the Division's

activities and is the controlling factor in the interplay between the

other three tasks. 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.

As part of the new emphasis on materials processing technology in

the Center for Materials Science, projects have recently been initiated

on rapid solidification and on the kinetics of grain boundary diffusion

and migration. Guidelines for producing more homogeneous alloys and

rules governing the formation of non-equilibrium alloy compositions,

metastable crystalline phases and metallic glass structures are being

developed by application of solidification theory to rapid solidification

conditions. Surface modifications introduced by diffusion-induced grain

boundary migration and by electron beam melting of surfaces with subsequent

rapid solidification are being investigated.

The emphasis in this work is on development of predictive techniques,

based on quantitative measurement and testing of predictive models. For

example, calculations which include surface tension effects and deviations

from equilibrium at the sol id- liquid interface show that in many alloys

plane front solidification will be obtained not only at slow solidification

velocities but also when sufficiently fast cooling rates are applied.

At these rates the usual dendritic mi crostructure will disappear and

much improved alloy homogeneity can be obtained. As a second example,

an apparatus especially designed to provide rapid controlled directional

solidification was used to show that metallic glasses are formed in

Pd-Si-Cu eutectic alloys when the solidification velocity is greater

than 0.2 cm/s. This result is consistent with theories which emphasize

the importance of eutectic crystallization rate rather than nucleation

rate in controlling metallic glass formation.

Significant success also was achieved in measuring convection

effects during directional solidification, in providing improved methods

of measuring liquid-vapor surface tension, and in developing ultrasonic

techniques for real-time measurement of solidification velocity. Changes

in alloy segregation resulting from solutal convection were used to

estimate the decrease in convection from applying magnetic fields during

solidification and by solidifying downward (liquid below solid). Experimental results in Pb-Sn off-eutectic alloys showed that magnetic fields up

307
to 0. 1 T had no measurable effect on alloy segregation arising from

convection but downward solidification greatly reduced this segregation.

Tests with a pulse-echo ultrasonic system on tin specimens show that

alloy solidification velocities up to at least 4 mm/mi n can be accurately

measured from either the solid or liquid side of the interface.

Diffusion- induced grain boundary migration is. an unexpected new phenomenon that produces greatly enhanced diffusion at low temperatures.

In recent experiments done as part of this task, appreciable alloying of

copper by zinc was found to occur at temperatures which are much too low

to allow measurable lattice diffusion. Since grain boundaries provide

easy diffusion paths, zinc atoms in these experiments are presumed to

enter the copper specimens by diffusion along grain boundaries. In

order to accommodate these additional atoms, the grain boundaries then

migrate and leave behind a zinc-alloyed region. Eventually the grain

boundaries can migrate across entire grains, thus producing in effect a large increase in volume diffusion. This effect can yield significant

alloying or surface degradation at surprisingly low temperatures. An

intriguing aspect of this process is that a small amount of actual

lattice diffusion apparently will prevent the effect from occurring.

In diffusion data work, compilations were prepared and evaluations

were made of kinetic parameters involving diffusion and reaction rates

in metal hydrides, proposed for use as hydrogen storage materials, and

of mass transport data in copper alloys and stainless steels. In order

to handle the diffusion data information efficiently, an effort has been

undertake'n to computerize the classification and bibliographic data for

documents in the Diffusion in Metals Data Center.

Task members were active in organizing a major international conference

on Rap i d Sol idi fi cation Processing: Pri ncipl es and Technologies held in

March 1980 and co-sponsored by Department of Defense agencies and NBS.

Also, task members serve on advisory committees for the 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.

Rapid Solidification

Subtask 1 of Task 12143

W. J. Boettinger, S. R. Coriell, R. J. Schaefer, J. W. Cahn

This project is focused on an increased 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 quantative experiments

are difficult to perform due to the high cooling rates and small specimen

sizes. This project is currently directed toward three areas: (a)

microsegregation as influenced by the shape stability of the freezing

interface, (b) thermodynamics, and (c) glass formation by rapid cooling of

308
eutectic alloys. In these areas, new theoretical predictions are being

examined experimentally but also experiments are being performed to

direct theoretical efforts in proper directions. Brief summaries of

progress in these areas are reported below.

Microsegregation and Stability at the Solidification Interface: The

phenomenon of sol id- liquid interface stability during directional solidification of a binary alloy was reexamined with special emphasis on very

rapid solidification rates ["Interface Stability During Rapid Solidification," S. R. Coriell and R. F. Sekerka, Rapid Solidification Processing : Pri nciples and Technologies , Volume 2]. For ordinary solidification

rates, the predictions of the perturbation theory of morphological

stability lead to results that are similar to those implied by constitutional supercooling; however, at very rapid solidification rates, the

perturbation theory predicts a vast increase in stabilization in comparison

to constitutional supercooling. There appear to be two dominant effects.

The first effect can occur even if there is local equilibrium at the

sol id- liquid interface; it is known as absolute stability and arises

because only short wavelength perturbations are important at high velocities and these are stabilized by surface energy. Numerical calculations

for aluminum with various concentrations of copper and a liquid temperature gradient of 2 (10 4

) K/m show that absolute stability is important

for solidification velocities_above about 0.01 m/s; in fact, for copper

concentrations less than 6x10 3 wt. percent, the interface is stable at

any solidification rate. The second effect is caused by departure from

local equilibrium at the solid-liquid interface. Although the exact

forms of such departures, let alone their magnitude, are not well known,

the perturbation theory can be modified to include their salient features.

Most departures from local equilibrium lead to increased stability. For

example, all constitutional effects will vanish as the distribution

coefficient approaches unity. Finally, other factors were examined with

an aim toward the identification of a realm where experimental test of

the theory would be meaningful, e.g. , solidification of a thin liquid

layer and growth into supercooled melts.

Experimental study of morphological stability during rapid solidification has been initiated, using dilute alloys of silver in aluminum.

In this system the concentration at which instability is predicted to

start falls within a range which is useful for experiments (0.1 to 1 percent Ag). At these compositions, instability can occur at solidification velocities greater than a critical value which is typically about

10 4 to 10 3 cm/sec, or less than a second critical value which is

typically about 1 to 10 cm/sec. The objective of the experiments is to

measure the stability to instability transition at the higher velocities,

which are not attainable by conventional unidirectional solidification

methods and which will therefore be achieved by electron beam surface

mel ti ng.

Preliminary experiments in which the electron beam was scanned

across the surface of aluminum and stainless steel samples demonstrated

the need for improved control and stability of the electron beam, and

these improvements are now nearing completion. In the experiments as carried out on the upgraded apparatus, the electron beam will be rastered

309
very rapidly over a small area of the metal surface to produce effectively

uniform surface heating with one-dimensional heat flow within this area. Calculations comparing heating by repetitive pulses to heating by a continuous source have been carried out to determine the rastering

frequency required to simulate the continuous heat source. Solidification

velocities are computed from a one-dimensional heat flow model. The

desired velocities are obtained by the use of heating times ranging from

4x10 3 sec to 10 1 sec and power densities from 5 x 10 7 to 5 x 10 8 W/m2

.

Thermodynamics : One of the current approaches to treating deviations

from local equilibrium (interface kinetics) during solidification is to

presume that while local equilibrium is not established at the liquid-solid

interface, it is established within each phase itself. This permits the

use of thermodynamic free energies of individual phases to draw conclusions

that restrict the realm of possible processes that occur during rapid

solidification. In a recently submitted paper ["Rapid Solidification",

J. W. Cahn, S. R. Coriell, and W. J. Boettinger, Proceedings of Symposium

on Laser and Electron Beam Processing of Materials, Materials Research

Society] such an analysis was used to place a bound on the maximum

extended solubility possible by rapid solidification for systems with

retrograde solidi. Predictions of this analysis are consistent with

experiments at other laboratories on the maximum solubilities of dopants

in laser melted Si. Other work in this area concerns metastable reaction

sequences and is presented in a recently submitted paper ["Thermodynamics

of Metastable Equilibria," J. W. Cahn, Rapid Sol idifi cation Processi nq : Principles and Technologies , Volume 2]. Thermodynamic principles rank

phase equilibria but not phases in a hierarchy of increasing stability.

Thermodynamics imposes precursor rules in multicomponent systems in

which a prior reaction is required before a phase can appear. A given

hierarchy persists over a domain on the phase diagram bounded by surfaces

on which the ranking of two equilibria changes. Multicomponent phases

per se do not form a hierarchy because a given phase can disappear and

reappear in a sequence of spontaneous processes. Processing for producing

metastable phases must place the system within a domain in which the

desired phases can form spontaneously from the available phases.

Glass Formation by Rapid Cooling of Eutectic Alloys : The relationship

between eutectic solidification and the ease of formation of metallic

glasses is being investigated. For many systems, crystallization,

including partitionless crystallization, of alloys into a single phase

solid is impossible over a wide range of composition near stable or metastable eutectics. This fact forces alloys to crystallize into

two-phase solids. Because of the need for diffusional sorting of the

components and creation of solid-solid surfaces, the kinetics of eutectic

crystallization are relatively slow and may be closely related to the ease of glass formation of these alloys.

Experiments have been reported ["Eutectic Solidification and the

Formation of Metallic Glasses," W. J. Boettinger, F. S. Bi ancani el 1 o

,

G. M. Kalonji, and J. W. Cahn, Rapi d Sol idifi cation Processi ng : Pri nciples

and Technol oqi es , Volume 2] on the directional solidification of Pd-6

at. % Cu-17 at. % Si alloys which show the evolution of microstructure as

310
a function of interface velocity. A structure of dendrites and interdendritic eutectic at low velocity (< 0.25 mm/s) becomes a fine eutecticlike structure at intermediate velocities (~ 1 mm/s) and finally the

alloy forms glass when crystallization is attempted at velocities greater

than 2.5 mm/s. Of particular interest is the observation and characterization of sharp interfaces which occur in these latter samples between

two-phase crystalline material and the glassy alloy.

Alloy Solidification: Solutal Convection

Subtask 2 of Task 12143

S. R. Coriell, W. J. Boettinger, R. J. Schaefer, F. S. Biancaniello

This research is directed toward an understanding of solutal convection caused by the simultaneous concentration and temperature gradients

present during the directional solidification of alloys. Included in

this study is investigation of the effects of convection on the microstructure and chemical homogeneity of directionally solidified alloys

and of the conditions under which undesirable effects can be eliminated.

The chemical uniformity and distribution of phases produced during the

solidification of alloys controls essential properties and performance

such as fracture and corrosion.

In a recently published article ["Convective and Interfacial Instabilities During Unidirectional Solidification of a Binary Alloy,"

S. R. Coriell, M. R. Cordes, W. J. Boettinger, and R. F. Sekerka, J. Crystal Growth 49, 13 (1980)], the onset of coupled convective and

interfacial instabilities during the directional solidification of a single phase binary alloy at constant velocity vertically upwards was treated by a linear stability analysis. The critical solute concentrations above which convection occurs and the spatial wavelength at the

onset of instability were calculated as a function of growth conditions

for lead-tin alloys. Very small solute concentrations can give rise to

convection, e.g. , for an interface velocity of 1 pm/s and a temperature

gradient in the liquid of 200 K/cm, tin concentrations greater than 3.2

(10 4

) wt. % cause convection. At present, the theoretical effort of

this task is directed at developing mathematical models of the fluid

flow and resultant solute segregation for conditions for which the

linear stability analysis predicts instability. This research is being

carried out in collaboration with Dr. R. G. Rehm of the Applied Mathematics

Division. Macrosegregation during solidification is commonly treated

through use of a stagnant boundary layer thickness 6. However, for

directional solidification in a container, there is no theoretical means

of calculating 6, and 5 is essentially a parameter used to fit experimental

data. By solving the relevant partial differential equations numerically,

we can predict fluid flow and solute distribution (and hence 6) during

directional solidification. Development of numerical algorithms for

these calculations is in progress.

Experimental research on the occurrence and suppression of solutal

convection in off-eutectic alloys and its effects on the microstructure

and macrosegregation has recently been concluded. The results are

311
described in a recently submitted article ["Solutal Convection Induced

Macrosegregation and the Dendrite to Composite Transition in Off-Eutectic

Alloys," W. J. Boettinger, F. S. Biancaniello, and S. R. Coriell, Met.

Trans A]. During upward solidification, liquid composition gradients

required to sustain plane front composite growth of off-eutectic alloys

provide liquid density gradients which cause convection for alloys with

compositions rich in the more dense component. This convection disrupts

the normal diffusion controlled growth of the composite and produces

undesirable macrosegregation and dendritic structures in solidified

samples. The effect of solidification velocity and alloy composition on the extent of macrosegregation was investigated. Experiments were also

conducted to determine if these undesirable effects could be eliminated.

Static magnetic fields of 0.1 T (1 kilogauss), which have previously

been successful in eliminating time dependent convection in liquid

metals, do not affect solutal convection and do not reduce macrosegregation.

Solidification downward (liquid below solid) virtually eliminates macro- segregation but is technically difficult and may be ineffective for

large diameter samples (> 3 mm) because of the long-range density gradient

induced by temperature.

Additionally, experimental study of convection during unidirectional

solidification is directed toward a confirmation of the predicted conditions

for the onset of convective flow. Because there are presently no methods

for measuring small-scale convective flows in opaque materials, the

experiments are carried out with a transparent material in which fluid

flow can be observed directly. After evaluating several measurement

methods, including laser doppler velocimetry, it was concluded that the

most information could be obtained by the photographic tracking of small

neutrally buoyant particles.

Experiments with particle tracking using 25 pm diameter latex

spheres (density 1.05 g/cm3

) showed good tracking of convective flow

patterns but gradual settling out of the particles. Therefore particles

with smaller diameters (2.0 pm) and lower density (1.02 g/cm3

) have been

obtained. The density of the convecting fluid is 0.98 to 0.99 g/cm3

.

The material used in these experiments is succi nonitri 1 e , an organic

substance which has been used extensively for analog studies of metallic

solidification. Most of the important physical properties of this

material have therefore been measured with considerable precision. The

experiments require the addition of a solute which is lower in density

than the succi noni tri 1 e , and ethanol has been chosen on the basis of its

similar molecular structure. The experiments require as a first step

the measurement of some of the properties of this binary system, and

these measurements are in progress. Measurements at low concentrations

of ethanol must be made under vacuum because air constitutes a significant

contaminant, but preparation of samples of known concentration under vacuum is difficult because of the widely different vapor pressures of

succi nonitri 1 e and ethanol. Procedures for preparing such samples have

now been developed.

312
Ultrasonic Measurement of Solid/Liquid Interface Position

Subtask 3 of Task 12143

R. L. Parker

Recent tests performed in the NBS Metallurgy Division, using a pulse-echo ultrasonic flaw detector to measure the position of the

interface in a melting or freezing tin specimen, indicate that this

method offers the possibility of precise, j_n situ , real-time, nondestructive and remote- readi ng measurement of solidification or crystal growth

in opaque substances such as metals or semiconductors.

In order to estimate the amount of reflected sound to be expected

from the solid/liquid interface of a metal, one must determine the

acoustic impedance Z = pc for each phase (solid and liquid) where p is

the density and c is the velocity of sound for longitudinal (compress! onal

)

waves. For a number of metals the velocity of sound is about 10 percent

less in the liquid than for the solid, and the density is 3 to 5 percent

less. Thus the acoustic impedance is 13 to 15 percent less for liquid

than for the solid, and from a simple formula for reflection at normal

incidence one can calculate that about 10 percent of the pressure of the

incident wave is reflected in the case of solid/liquid tin.

The tests were made on 99.9 Sn at 5 MHz. The transducer contacts

the cold end of a 8 mm diam. x 200 mm long specimen in a graphite mold

in a Bridgman gradient furnace (unidi rectional melting/solidification).

Sharp echos easily locate the interface position, to ± 1 mm, over the

range of velocities tested to ^ 4 mm/mi n). Some tests were also made

at 2.25 MHz from the liquid side, in larger specimens, with similar

results.

Further NBS work will attempt to identify measurement factors

inherent in use of the method for measurement, feedback, or control in

either industrial or laboratory solidification applications such as continuous casting of metals or the solidification of solar photovoltaic

materials. Such factors may include signal generation and detection,

frequency effects and attenuation, interface modeling effects, and

spectrum analysis and correlation techniques. Appropriate signal processing

techniques should make it possible to improve signal/noise ratios and to

isolate the characteri sties of the solid/liquid interface from such

factors as the transducer response or attenuation in the adjacent material.

Surface Tensions and Their Variations with Temperature and Impurities

Subtask 4 of Task 12143

S. C. Hardy

The surface

melting point to

The measurements

of hydrogen with

materi al s , i . e.

,

The cup material

tension of liquid gallium has been measured from the

over 600 °C using a contained sessile drop technique,

have been performed in high vacuum and in atmospheres

the drops resting in cups of a variety of different

pyrex glass, quartz, alumina, boron nitride, and graphite,

has proved to be critical in these measurements because

313
reaction with the liquid gallium or diffusion of impurities from the cup

leads to contamination of the sessile drop. This is seen as a surface

tension depression at low temperatures due to surface adsorption of

these impurities. Consistent and reproducible surface tension values were obtained only with cups of ultra high purity graphite which had

been baked at 900 °C for several days in high vacuum before forming the

sessile drop under flowing nitrogen. The same surface tension variation

with temperature was measured in high vacuum and static reducing atmospheres

of hydrogen for these cups. A non-linear least squares analysis of the

data showed that the surface tension could be described as follows:

y = 709.9 + 0.0016 (T-29.87) - 0.0000923 (T-29.87) 2

where the surface tension y is expressed in units of mJ/m2 and the

temperature T in °C. The surface tension of gallium measured with

quartz cups in hydrogen closely followed the above function also. With

quartz cups in vacuum, however, the measurements indicated surface

adsorption at low temperatures. The impurity is probably an oxide which

is effectively reduced in hydrogen but not by heating in vacuum. The

results described by the above relationship are in excellent agreement

with two previous measurements when inaccuracies in the density data

used in those works are taken into account.

In addition to the surface tension measurements, we have made

extensive observations of liquid gallium surfaces in an Auger spectrometer

in collaboration with Dr. Joseph Fine of the Surface Sciences Division.

Oxygen and carbon have been found to be the major impurities on the

gallium surfaces. After heating, these impurities are segregated into

thin patches which float on the surface. Argon sputtering of the liquid

results in a complex fluid flow which brings the impurity islands into

the ion beam where they are sputtered away. In this way it has been

possible to produce gallium surfaces which are free of impurities and

remain so within our measurement capabilities for many hours. Although

the configuration of the Auger spectrometer is not ideal for sessile

drop measurements, several such measurements made at the melting point

for sputtered clean surfaces gave values near the result cited previously,

i.e., about 702 mJ/m2. An Auger spectrometer designed for simultaneous

surface tension measurements is nearing completion and will be used to

study segregation of various species at the surfaces of pure liquid

metals and alloys of low vapor pressure.

Diffusion Kinetics

Subtask 5 of Task 12143

J. R. Manning, D. B. Butrymowicz, J. W. Cahn

Because of crystal defects, diffusion of atoms in alloys often occurs by very non-random processes. A striking example of a non-random

diffusion process is the surprisingly fast diffusion of zinc into a-brass

at low temperatures found in recent experiments done at NBS. This large

unexpected effect can be shown to result from diffusion-induced grain

boundary migration, a newly-discovered phenomenon in which the introduction

314
or depletion of impurity atoms by diffusion along grain boundaries makes

the boundaries themselves move. Other non-random diffusion effects are provided by flows of vacancies and interstitials through metals. As

part of the current work, equations have been developed for the effect

that these flows can have on the segregation produced in alloys undergoing

irradiation in nuclear reactors. Relations between the actual and

effective (random) number of atom jumps as influenced by the defect

gradients in these alloys have been developed. Some of the results are similar to those for interdiffusion in alloy coatings. It is found that

driving forces arising from these gradients can strongly influence the

diffusion equations.

In the diffusion-induced grain boundary migration experiments,

copper polycrystall ine specimens were exposed at 200 °C to 400 °C to

zinc vapor produced from a-brass chips. These temperatures are much too

low to allow any significant lattice diffusion. Nevertheless, a rather

uniform addition of zinc in the interior of the grains was observed to occur. The explanation proposed for this process is that alloying

elements move along grain boundaries and penetrate much more deeply

there into the base material than elsewhere. That diffusion then makes

the boundaries themselves migrate, leaving alloying elements behind in

the region the boundary has traversed. Experimentally this grain boundary

migration is found to occur only in the grain boundary diffusion zone

and under conditions where a sharp concentration gradient is maintained

across the moving grain boundary. Thus, it is expected that the effect

will be important at temperatures low enough so that lattice diffusion

is negligible but high enough so that grain boundary diffusion still occurs. Grain boundary migration also has been found to accompany rapid

de-zincing of a-brass at these low temperatures. Since this process

produces an effectively greatly enhanced volume diffusion, it has major

implications for surface alloying and coatings, leaching and degradation

of surface properties, thin film technology, metal contact integrity,

and cellular precipitation. Aspects of this effect that are being

investigated include the temperature and composition ranges in which

this effect is significant and relations between the diffusion rates,

grain boundary migration velocities, and magnitudes of the concentration

steps at the grain boundaries.

The effect of defect fluxes in making actual atom jump frequencies

differs from those expected under random conditions has been analyzed in

terms of the independent atom displacements. These independent displacements

are not the individual atom jumps but instead involve a complete series

of jumps involving an atom and a particular defect, either vacancy or interstitial. Even though the effective random jump frequencies differ

greatly from the actual jump frequencies, it can be demonstrated that

the difference between the number of effective jumps in directions with

and against the force provided by a defect gradient exactly equals the

difference between the actual jumps. Irradiation produces defects in

the interiors of alloys and thus produces such gradients. The atom

fluxes which give rise to segregation effects are determined, of course,

by the differences between the actual atom jumps with and against the

315
defect gradients. The current work provides a prescription for describing

this difference in terms of four driving forces which influence the

effective jump frequencies in irradiated alloys. Large segregation

effects are predicted.

Diffusion in Metals Data Center

Subtask 6 of Task 12143

D. B. Butrymowicz, J. R. Manning, M. E. Read

Many metallurgical processes, such as heat treatment, use of protective

coatings, sintering, welding, and gas/metal interactions, depend on an understanding of quantitative data for diffusion. The NBS Diffusion in

Metals Data Center provides a unique central source where data from the

technical literature involving diffusion and related kinetic reactions

are collected, analyzed, and compared. Critical reviews are published

and inquiries from the technical community for data on particular alloy

systems are serviced. More than 23,000 papers reporting diffusion data

now are on file. To allow ready retrieval, these references are classified

according to the alloys on which they contain data.

In order to handle this information efficiently, an effort has been

undertaken to computerize the bibliographic and classification data in

these files. New computer hardware has made it possible to record

locally, in machine-readable form, information concerning technical

documents. Further steps are being developed to capture bibliographic

records from on-line data bases and through local editing capability to

add our specific indexing information. A complete file of ternary alloy

systems for which diffusion data are available, over 2000 in number, has

been input locally onto floppy disks, which are searchable and updatable

locally also. The ternary files may now be searched and sorted in

various ways not possible previously when purely manual techniques were

used.

A compilation and critical evaluation of thirty- three candidate

hydrogen-storage materials for eighteen different physical and chemical

properties, including reaction rates, diffusion coefficients, and other

kinetic properties has been completed. This project carried out jointly

with personnel from the NBS Alloy Data Center resulted in 660 data

sheets being prepared. This information will be disseminated by Lawrence

Livermore Laboratory, where an on-line data base for these materials is

being established.

Further funding was received from the International Copper Research

Association (INCRA) for compilation and critical evaluation of diffusion

data in selected copper alloy systems. This project is part of a continuing

program with the copper industry's trade association to provide it with

handbook data pertinent to transport processes and relevent to research

and development activities of this industry.

Cooperative efforts with Argonne National Laboratory were initiated

to bring about the collection and evaluation of transport data in stainless

steels employed in reactor systems. The Data Center has already within

316
its files a large fraction of the world's literature pertaining to these

critical alloys and efforts are being made to integrate our evaluation

activities with the experimental activities, leading to a recommended

set of diffusion rate values for substitutional stainless systems.

Metals Processing Laboratory

Subtask 7 of Task 12143

W. J. Boettinger, F. S. Biancaniello, J. C. Orbock, S. D. Ridder,

R. J. Schaefer, R. D. Shull

The primary research endeavor of this laboratory is new and innovative

metals processing technology. Some of these processes include electron

beam surface melting which produces rapidly solidified surface layers.

These layers are used both for the study of the effects of rapid solidification on microstructure and for wear and abrasion studies. Also, a vacuum melt spinning device is being constructed to produce rapidly

solidified ribbons for the study of the morphology and structure of bulk

metallic glasses and metastable crystalline compounds. Another new area includes the design and construction of a device for the measurement of

convection and segregation during semi-continuous castings of low temperature alloys under axi -symmetric heat flow conditions.

A program conducted in the Metals Processing Laboratory during the

past year is concerned with the metallurgical processing of aluminum

alloys. This task simulated industrial casting and thermomechanical

processing practices in the production of 2219 aluminum alloy. Such

alloys have been the subject of concern in the aerospace industry. The

objective of this research was to elucidate the relationships between

macrosegregation, microstructure, and mechanical properties.

This investigation involved special casting geometry to simulate

industrial macrosegregation characteristics and subsequent examination

of these cast ingots to determine the effect of chemistry variations on properties. Thermomechanical processing of as-received 2219 plates was performed to obtain data necessary for determination of Time-TemperatureTransformation diagrams and C-curves. Also an ingot of directionally

solidified 0 phase (Al 2 Cu) was prepared for microprobe studies.

A major effort has been the modernization of the entire laboratory.

A data acquisition system has been ordered to simplify data collection,

manipulation, and experimental control. The entire heat-treating part

of the laboratory is being consolidated and temperature control modernized.

A summary of the past year's activities supporting other programs

fol 1 ows:

o Prepared Pd 77 Cu 6 Si 17 and related alloys for rapid solidification

studies and for phase identification of the resulting microstructures. Silver-copper eutectic was prepared in conjunction

with this research.

317
0

0

0

0

0

0

0

0

0

Prepared a series of dilute Al-Ag alloys for determining

planar vs cellular growth at high velocities obtained by

rapidly scanning in electron beam.

Prepared Cu 15 w/0 Ag, Cu 3.5 w/o A1 and Cu 7 w/o A1 alloys

for sliding wear test materials for studies on microstructures

relating to the friction and sliding wear behavior of metals.

Prepared 1020 steel for abrasive wear tests.

Prepared 0-2 tool steel and pure copper for pin on disk wear

tests.

Prepared Ti-Al alloys (with and without Mo and Nb) in conjunction

with an effort to determine the Ti-Al phase diagram and the

effects of adding p-stabil izing elements.

Prepared Cu-Ga-Ge alloys as part of an investigation to determine

whether massive transformations require nucleation at grain

boundaries.

Prepared directionally solidified Auln2 and zone refined AuA 1 2 boules for use in superconductive devices for temperature

fixed points.

Prepared Ni-Al alloys and Ni 8 w/o A1 single crystal for

neutron diffraction studies.

Prepared ultra thin foils and various heat treatments on metals and alloys in support of other Division activities.

318
ALLOY DURABILITY FOR WEAR APPLICATIONS

Task 12144

The activities in this task are directed toward the measurement of

the properties and performance of alloys that are used (1) in service

under wearing conditions and (2) in applications as synthetic implants

in humans. Primary emphasis in both areas is directed toward improved

methods of properties measurement and testing of alloy performance under

appropriate conditions. Further, considerable emphasis is directed

toward the need for better fundamental knowledge and accurate, useful

data on the mechanisms and processes of wear, fatigue, corrosion, and

fracture of metals as they apply to these uses.

The impact of the wear processes on U.S. technology in terms of

lost productivity, loss of critical materials, safety and general economic

costs has been estimated to be in excess of $30B to $50B per year.

While wear is an extremely complex phenomenon, frequently involving

several interacting mechanical and chemical processes, it is generally

agreed that an improved understanding of the materials science aspect of

the problem should offer the best opportunity to control wear costs.

Efforts in this task are selected with this consideration in mind. An

increased effort in this task has resulted from the FY80 Durability

initiative, permitting the addition of three technical staff members.

New projects have been initiated in the areas of galling wear, fatigue

wear, and abrasive wear of composite materals. Task personnel hold

leadership positions in the ASTM Committee G-2 on Erosion and Wear in

order to ensure the effectiveness of our contributions in measurements

and standards to industry. One of our staff holds a patent on a newlydeveloped wear resistant alloy. Another staff member is Program Chairman

for the Third International Wear of Materials Conference scheduled for

early 1981 at which over 125 research papers on various aspects of wear

are scheduled for presentation.

In the area of synthetic implant materials science, task members

organized and carried forward at NBS an International Conference on Implant Retrieval this spring. At this meeting, leading research scientists

and physicians described the current state of understanding of implant

failure and success in service. The emphasis in our research program on fatigue, corrosion, and compatabi 1 i ty characteri sti cs of implant alloys

is completely consistant with the emphasis presented at this Conference

and the Workshop that followed it. In this area also, task members

provide significant leadership on the ASTM-F4 Committee on Medical and

Dental Materials and Devices to insure effective contribution to the

needs of the industry and the public.

The task is divided into four subtasks whose activities and accomplishments over the past year will be described next. These subtasks are:

Mechanisms of Metallic Wear, Lubricated Wear, Wear Standardization and

NDE, and Metallic Biological Implants.

319
Mechanisms of Metallic Wear

Subtask 1 of Task 12144

A. W. Ruff, L. K. Ives, P. Blau, K. J. Bhansali, F. Matanzo

Several projects in this subtask are studying the mechanisms of

wear under different conditions of dry sliding and abrasion. It is

necessary to carefully design these experiments in order to avoid complications due to multiple wear modes acting and possible environmental

complications. One project is examining the effect of mechanical properties

changes in several steels and copper alloys on the plastic deformation

mode of wear. A computer controlled block/ring wear test machine is

used. The alloy specimen is maintained in an argon atmosphere during

wear to control environmetal interactions. Wear tests are carried out

at fixed load and speed for total sliding distances up to 700 meters.

Both friction force and wear displacement are continually recorded and

stored as digital data. This permits subsequent data smoothing and

correlation analysis. Wear debris is recovered from these experiments

for examination along with studies of the worn surface and subsurface

microstructure. Results have been obtained so far on three different

steels (a tool steel, low carbon steel, and dual-phase steel) and on copper and two copper-aluminum alloys. Mechanical properties measurements

of the work hardening characteri sties of the steels have also been made

for comparison with the wear data. Results indicate that when plastic

deformation processes are the dominant mode of wear, the tendency for an alloy to accommodate larger amounts of plastic strain at a given stress

level is reflected in a lower wear rate. A wear debris formation mechanism

has been identified that involves the repeated deformation and eventual

ductile failure of surface protrusions. The dual phase steel alloy

appears capable of accommodating greater amounts of wear deformation

before metal is detached to form wear debris. A talk describing these

results was presented at Cornell University this spring. Future plans

include studies of several other steels exhibiting extended ductility

under multiaxial loading conditions. Electron microscope methods will

be applied to measure the depth of wear damage and the effect of microstructure such as grain size and orientation on the distribution of

subsurface damage.

Abrasive wear mechanism studies are being carried out on steel and

on surface modified alloy specimens. Low carbon steel specimens have

been heat treated to produce different microstructures so that the

influence of phase type and distribution can be examined. The effect of

small amounts of water (400 ppm and less) on the abrasive wear of steel

is being studied. A cooperative study with the Naval Research Laboratory

of the abrasive wear process in surface modified alloys is underway.

Laser surface melting of aluminum, nickel-based, and titanium alloys is

carried out and particles of tungsten carbide and titanium carbide are injected into the melted surface before it is rapidly solidified. This

process forms a composite surface layer having a hard phase particle

concentration up to 50 percent by volume. The abrasive wear resistance

is increased up to 50 times. Studies of the effect of particle size,

spacing, type, and alloy composition and structure will be carried out

to better understand the abrasive wear mechanism in these composite

surface layers.

320
Another phase of this work deals with the role of microstructure in

determining the wear-in behavior of metal surfaces. A computer controlled,

stroke-by-stroke wear and friction tester was built to study the manner

in which microscopic changes at and beneath sliding surfaces affect the

rate and severity of surface deterioration. Computer graDhics methods

are used in the analysis of a time record of friction changes at selected

locations on the sample surfaces. Effects of test environment, microstructure and material composition were seen to strongly influence wear-in

behavior of copper, aluminum, bronze, and several steels. Continuing

studies for the coming year will address crack initiation and propagation

in worn surfaces during the wear-in period.

A new project is cocerned with the mechanisms of scuffing and

galling wear. These wear processes frequently render parts of components

of mechanical systems inoperative even thougn very small amounts of

material have been removed. Under lubricated conditions, failure of the

lubricant and associated scuffing causes localized wear which often

causes total breakdown of the lubricant. Very little is known aDout the

influence of basic materials properties on scuffing and galling wear.

In the past, selection of materials for a wear couple has proceeded

mainly on an experimental basis. Such a selection process invariably

leads to overdesigned systems as well as specification of expensive

alloys which use critical strategic metals, e.g., cobalt base alloys.

This project will examine the detailed mechanisms of scuffing and galling.

Particular attention will be focused on the influence of intrinsic

properties such as stacking fault energy and on the microstructure of

the alloys. A simple test unit capable of loading engineering and

special alloys up to their yield strengths during sliding is be'ng

designed and built. The worn specimens and the wear deoris will be

characterized by means of scanning and transmission electron microscopy.

Attempts will be made to correlate the surface topography, subsurface

microstructural changes, and mechanical deformation to intrinsic metallurgical properties of the alloys.

Another new project supported by the U.S. Army Materials and Mechanics

Research Center concerns the use of metal matrix composite materials.

The interest here is in lightweight composite aluminum alloys for use as structural materials in wearing applications. Aluminum alloys generally

offer a low and unacceptable wear resistance. Composites of aluminum

alloys with hard particles such as alumina and silicon carbide are expected to offer considerably improved wear resistance in combi nation

with high strength-to-weight ratios. This project is aimed at understanding

the wear modes in composites to help select optimum process parameters

as well as compositions for maximum benefits.

Lubricated Wear

Subtask 2 of Task 12144

L. K. Ives, A. W. Ruff, M. Peterson, H. C. Burnett

One project in this subtask is directed toward the development ana evolution of bench wear tests for the characterization o

T

‘ "ere 1

’''' ~ec engine oi's. The project is supported by the NBS Recycled Oil Program

321
which was established in response to the Energy Policy and Conservation

Act of 1975. That Act directs the NBS to develop tests to establish the

substantial equivalency of recycled oils to virgin base oils. During

the past year this project has been concerned primarily with the evaluation

and development of tests employing the standard ring and block specimen

configuration. Existing ASTM test methods have been examined as have

several variants of these methods. Test conditions are carefully controlled

and the friction and thermal response of each oil under investigation is

monitored and recorded. An important component of the evaluation procedure

involves the examination of worn metal surfaces by means of scanning

electron microscopy. These studies are aimed at relating metallurgical

and surface morphological characteristics to the wear test response of

different oils. Some initial results of this work were presented in an invited paper at the 1979 conference sponsored by the Recycled Oil

Program, ASTM Technical Division P, and the Mechanical Failures Prevention

Group. Current studies indicate that one test method, the Suntech

Timken Method, is especially promising with respect to the characterization

of the wear response of engine oils. Through application to a series of

HID engine sequence test reference oils, it has been found that the

Suntech Timken test is capable of discriminating among these oils and

ranking them in agreement with their known performance. Moreover, these

results are of particular significance because they can serve as the

basis for the construction of a reference scale to which the behavior of

oils having unknown performance may be compared. Based on this approach

studies are currently underway to determine the extent to which additive

response of selected recycled base oils may be determined for different

metallurgical combinations. In a related activitiy, personnel from the

Postal Service Research Laboratory have visited our laboratory to examine

the test methods developed here for lubricated wear studies in connection

with a serious wear and failure problem experienced in their operations.

A second project, supported by the Office of Naval Research, concerns

the study of the friction and wear properties of an experimental solid

lubricant, SbSbS 4

. This compound has an amorphous structure and is

obtained in the form of a finely divided powder. When applied as a grease additive SbSbS 4 has been reported to confer outstanding anti-wear

and anti -seizure capacity—much in excess of that achieved with MoS 2 and

most organic additives —in four-ball and pin and V-block tests. These

results have been confirmed in our own studies. Our work seeks to

understand the mechanism by which SbSbS 4 functions as a lubricant, the

extent to which the compound may serve as a lubricant for various metals

in contact including stainless steels, and the range of contact conditions

of load, speed, and temperature over which it is effective. Preliminary

differential scanning calorimetry examination and thermal decomposition

studies suggests that the availability of active sulfur to react with

the metal surface plays an important role in the function of SbSbS 4

. In

typical wear tests conducted with the pin and V-block and four-ball test

machines, contact temperatures are characteristically high and SbSbS 4 as

a grease additive is very effective in reducing friction and wear. When

a ring compression friction test was used, however, SbSbS 4 was found to

be relatively ineffective as a 1 ubricant--far less so than MoS 2 , for

example. In the ring compression test relatively high stresses are

322
achieved at the metal -metal contact without an accomcany: ng '''se in

temDerature. To extend these studies of the friction and wear characteristics of SbSbS 4 to cover a wider range of contact conditions, a pin-on-disk

test machine capable of elevated temperature operation, low si 'ding

speeds and high loads has been designed and constructed Additiona'

studies utilizing electron microscopy a^e underway to investigate t~e

structure of SbSbS 4 before and after exposure to sliding contact.

Electron microscopy studies of the composition arc structure o f wormetal surfaces are also planned. The mechanism of «ear anc "rcton

reduction by this comDOund on di~~erent a'loy su^-aces should ce deter-* nec through these various approaches.

Task memDe'rs provide leadership to tr.e ’*tecnan' ca' r = ''-’'es ^reve-t* zr Group which stimulates voluntary cocoeration among a" segments of re

national scientific and engineering communities i- efforts to T'ec-ce the

incidence of mechanical failures and to ceveloo methods to predict

mechanical failures. During FY80 the M FPG was invo'ved in two conferences;

a joint conference on Measurements and Standards *cr Recyc'ec 3i 1/Systems

Performance and Durability, and a conference on Failure Prevention in

Ground Transoortation Systems. Both Conferences were he : d at N3S ard

were well attended. They provided gooc oDcortunity ^or technics' d' scissions in these important areas. During FY81 two technical conferences a^e

planned. These involve the subjects of: 'Detection, Diagnosis, and

Prognosis: Contributions to the Energy Challenge,' 7-9 Cctober '980,

Los Angeles, California, and "Aircraft Maintenance ~ecbnologv. 2' -23 Apr"'

1981, NBS, Gaithersburg.

wear Standardization ana NCE

Subtask 3 of Task 12144

A. W. Ruff, L. K. Ives, P. J. Blau

One project is concerned with tne development of -eta' standard

reference wear test specimens for an abrasive -ear test, that is w'dely

used in industry. Abrasive wear is one of the most frequently encou~terec

forms of wear. In industry it has been estimated that teases 50 ce-'ce-t

of all wear can be traced to this source. Excavating, mining, anc agricultural machinery as well as a variety of equipment -sec *- processing

and handling abrasive materia' must ce designee to -i-'-ize abrasi.e

wear whi 7 e maintaining the structura' integrity associated with, ore''

functions. Accurate data and accrccr-'ace test crocedunes are necessar. both for eauioment design purcoses and to assist i~ t~e development of

mo^e economica' and/or imoroved materia' s. ~*e dry ss~g rubber tree'

abrasive wear test is found to yield results that correlate wel ' «'C"

service behavior when the stresses imposed on abrasi.e oartie'es are relatively small, i.e.

,

appreciable fracture and crushing o* the aoras'.e

do not occur—and when the abrasive particles are not *, igia'y sucoortec.

Fol ' owi ng nearly five years of e^'ort, the ASTM Cc -- ' ttee 3-2 c~ E*'Osion

and wear has developed an approved sta'carc method for t~e dr*, sane --cce"

wheel abrasive wear test. Project sta~* -er'ce”S nave ~aoe s'i"'~'ca~t

contributions to that effort cot" 'n writing t~e standard and through

participation in several '’ound-rob'n test series.
Development of suitable reference specimens for this test method is now underway at NBS. This effort involves the selection and preparation

of appropriate materials and the demonstration of good repeatability in

the test results. As a prerequisite to realizing these goals it has been

necessary to carry out a detailed evaluation of the test procedure and

to determine the influence of several test variables on measured wear

rates. On the basis of our own studies and the recommendations of

other G-2 Committee members employing the dry sand/rubber wheel test,

two materials, D-2 tool steel and 1020 carbon steel, have been selected

for development as SRM's. Tentative arrangements have been made for the

manufacture of one thousand D-2 tool steel specimens which will be sold

as abrasive wear reference specimens by NBS. It is anticipated that

similar arrangements can be made for the preparation of 1020 steel

reference specimens in the near future. Plans for next year also include

a new effort to evaluate abrasive particle characteristics (as well as metal wear debris particles) using quantitative metal 1 ographic methods.

Future development of reference abrasives for uniformity in wear testing

methods will be explored.

Another project is concerned with the nondestructive monitoring of

wearing systems and is supported through the NDE office. Two approaches

are used in this work: (1) a study of wear debris particles in order to

identify the type and severity of wear taking place in an operating

system, and (2) the application of acoustic emission detection techniques

to monitor fatigue or delamination wear modes in metals. An instrumentation

system has been assembled this year to apply acoustic emission methods

to a block/ring wear tester. The system involves a broad-band AE transducer,

a variable gain amplifier and filter system (up to 100 db gain), and a modified video tape recorder. Specimens containing preexisting cracks

in the wear-affected zone will be studied. Noise and emission spectra

will be recorded and then played back through the Division's AE signal

processing equipment to identify and quantify relevant signals. Spectral

analysis and fourier transform methods will be applied.

Metallic Biological Implants

Subtask 4 of Task 12144

A. C. Fraker, A. W. Ruff, G. J. Mattamal , J. S. Harris, A. C. Van Orden,

G. A. Danko

Recent times have seen considerably increased use of metals as surgical implants. Research efforts and clinical studies have been

applied to produce improved performance implant materials. This is

evidenced in the increased use of titanium alloys and improved cobaltchromium-molybdenum alloys (hot i sostatical ly pressed; forged). The

purpose of this subtask is to study metals currently used or considered

for use as surgical implants. Mechanical properties and chemical reactivity

are investigated to obtain data on corrosion behavior, corrosion-fatigue

life, wear, fretting, and metal -protei n interactions. Variations in

heat treatment and in some cases, the application of surface coatings

are used in an effort to improve implant materials. Drs. Pei Sung and

M. Ashraf Imam participate in this project as guest workers from the FDA

324
and George Washington University, respectively. The collaboration with

Dr. Imam deals with mechanical property and corrosion fatigue studies

and how these are affected by changes in the microstructure. One investigation with Dr. Sung was completed recently and this dealt with coupling

of dissimilar metals to utilize the best properties of each for the

implant. From the standpoint of corrosion behavior, it was determined

that the designated implant alloys of cobalt-chromium-molybdenum, cobaltnickel, and titanium-6 aluminum-4 vanadium probably would be acceptable

as coupled materials. Continuing research with Dr. Sung will deal with

repassivation of individual metals and with effects of surface ion

implantation of carbon, nitrogen and boron. Techniques employed in this

work include potentiostatic polarization, transmission and scanning

electron microscopy, ultra filtration of proteins, atomic absorption,

calorimetry measurements, and torsion fatigue testing.

Studies on the relatively new titanium T

i -4A1 - 1 . 5Mo-l . 5 Cr alloy

which is being considered for implant use, have been carried out in

three areas: microprobe analysis, microstructural study using transmission

electron microscopy, and corrosion behavior study. The purpose is to

determine the extent of alloy i nhomogeniety and to identify the phase

structures and distribution. Microprobe analysis was performed on samples after three different heat treatments. The exact chemical

composition of the phases was determined. The analysis showed the

matrix composition of the two phase samples to be lower in Ti and A1 and

higher in Mo and Cr. Samples of four different heat treatments of the

material were examined using transmission electron microscopy which

allows detailed microstructural study of the material including electron

diffraction. Anodic polarization measurements have been conducted to

study the behavior of the alloys in simulated body saline solutions.

Specimens of several different heat treatments of the material have been

studied. More anodic polarization tests are planned including tests to

determine the effect of Mo and Cr in the alloy on the corrosion behavior

in a solution containing the amino acid, cysteine, which has a sulfur

containing ion. A pitting corrosion test for an ASTM round-robin test

was also carried out on a 316 stainless steel alloy. Future plans

include the study of several cobalt-based alloys using these techniques.

We will also explore the possibility for a reference material to be

provided by NBS for use in a standard method for crevice or pitting

corrosion being developed by ASTM.

A major accomplishment this year involved setting up a torsional

corrosion-fatigue machine for studying the fatigue life of implant

metals. Tests are being conducted under fully reversed torsion at a constant shear strain amplitude and frequency of 1 Hz in a flowing

physiological saline solution at 37 °C and pH of 7.4. The effects on fatigue strength of changing the alloy microstructure through heat

treating and quenching are being determined. The Ti-4.5Al-l.5Mo-l.5Cr

alloy and the improved cobalt-chromium alloy in the forged high strength

and micrograin conditions are being studied at George Washington University

and at NBS. This is a cooperative program involving Dr. M. A. Imam of

the George Washington University. A scanning electron microscopy study

of the fatigued specimens has been initiated to give an insight to the

325
complex relationship between environment, loading mode, and microstructure.

Emphasis is being placed on the failure mechanisms and identification of

crack initiation sites. A transmission electron microscopy study is

being conducted to determine if transformations in the microstructure

occur under the cyclic loading condition. Results from the fatigue

tests were published in the Proceedings of the 4th International Conference

of Titanium in May, 1980, in Kyoto, Japan.

An investigation is underway to study the binding of metal ions to

proteins in human blood albumin (HBA) in connnection with the general

problem of implant alloy compatiblity with the human system. Measurements

are being made of the concentrations of bound nickel ions in HBA.

Methods of ul traf i 1 tration and atomic absorption spectroscopy are being

used. Microcalorimetry techniques are also being applied to the determinati

of the bond energy involved. Preliminary results have been obtained for

the heats of reaction involving both a 3 percent HBA protein solution

and a 3 percent amino acid solution with solutions containing from 10 to

100 ppm Ni. Potentiometric titration studies are planned for next year

to supplement the data from these other methods.

A second study of metal -organic reactions has been undertaken in

which we are concerned with potentiostatic corrosion of 316 L stainless

steel in a human serum albumin (protein) solution. The amount of chromium

and other ions released into solution from the alloy are quantified

through the use of atomic absorption spectrophotometry to determine the

efficiency of the reactivity of implant materials i_n vi vo and their

relationships to human metal ion sensitivity and failure modes such as corrosion fatigue.

Fretting wear studies of implant alloys are being planned for the near future. Two different apparatus have been designed, constructed,

and tested for exposing implant alloy specimens to simultaneous fretting

wear and potentiostatically controlled corrosion. Both apparatus simulate

the geometry and conditions present at a screw-screw hole interface such

as is found in many fracture fixation devices. In one system a rotating

fretting motion is applied; in the other system, a rocking fretting

motion is applied. It is possible to control the loads and amplitudes

of the fretting wear motion as well as the solution chemistry and electropotential. The wear debris produced during the experiments can be

recovered and studied along with the worn surfaces. Since fretting

processes are characteristically slow under actual conditions, experiments

will be carried out for long terms of several hundred hours. Current

efforts involve the design and construction of a digitally controlled,

computer interfaced potentiostatic system for the fretting experiments.

The system would permit continuous monitoring of the experiments and

alteration of test conditions as appropriate.

326
CHEMICAL METALLURGY FOR DURABILITY

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.

A joint effort mandated by agreement between the Directors of the

National Bureau of Standards and the American Society of Metals (ASM) has

been undertaken 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). ASM continues to support a Research Associate at NBS for this project. A semi-annual Bulletin of

Alloy Phase Diagrams is also published under this program.

The phase diagram of the Ti-Al system is being studied experimentally

with a number of different techniques as a part of a Navy program to

improve titanium processing technology. In addition, phase diagram data

are being exploited in the solution of problems in areas of critical

national need; for instance, materials are selected for study as electrocatalysts in hot phosphoric acid on the basis of available phase constitution

data; here, surface phase stability is of utmost importance. In fair

measure, the task members' established scientific competences are challenged

and stimulated in the course of this work; for example, studies of

alloying led to fundamental inquiry into the definition of electronegativity

concepts; catalysis research on non-noble alloys required better understanding

of the electronic structure of refractory hard metals and of the definition

of charge transfer in these materials; modeling of thermodynamic functions,

necessary for phase diagram prediction and an aid in critical evaluation,

led to development of a method for applying d-electron energy band

parameters to prediction of heats of formation of transition metal

alloys. Mossbauer techniques have been used to quantitatively identify

phases in several materials. New results have been obtained in a DOE-DOD

fuel cell catalyst program. We are working on the NASA soft A1 project

focusing on the understanding of both stable and metastable phases

produced by processing, and devising methods for nondestructi vely detecting

them by hardness, eddy current, and positron annihilation measurements.

New work on the latter completed this year is described under "Alloy

Properties Science for Structure Characterization. " The new initiative

on materials processing includes proposed phase diagram work. Task

workers are strongly involved in committee work including Chairmanship

of the Committee on Alloy Phases of the Metallurgical Society of AIME.

328
Our work is described in more detail in the following three sections:

Alloy Phase Stability, Alloys for Fuel Cells and Catalysis, and Nondestructive Evaluation of Nonuniformities in 2219 Aluminum Alloy Plate Relationship

to Processing.

Alloy Phase Stability

Subtask 1 of Task 12145

L. H. Bennett, J. R. Cuthill, J. L. Murray, L. J. Swartzendruber

,

R. Shull

We are pursuing a program of three interconnected parts: critical

data evaluation and compilation of phase diagrams; experimental phase

diagram work on systems selected to support the evaluation program; and

the theory of alloy phase stability, this year stressing application of

energy band theory to the prediction of the heat of formation of alloys.

The Alloy Data Center has established a collaborative alloy phase

diagram critical evaluation program with the ASM. This joint effort has

two key aspects: (1) development of an on-line indexed bibliographic

system starting with the current ASM automated system for the METADEX

data base; and (2) the organization and preparation of critical compendia

for binary and multicomponent alloy phase diagrams. On the first aspect,

significant improvements have been made in the METADEX system, including

more thorough scanning of literature sources and more extensive indexing,

and a contract has been let to provide separate, quicker access to the

subset of alloy phase diagram data. To achieve the second aspect of

this joint program, an International Council of distinguished experts

has been established to advise on various aspects of the critical evaluation

effort, and panels formed to deal separately with binary and higher

order systems. In the binary effort, Joanne Murray has been appointed

Category Editor for Ti. A first set of ten evaluated systems should be

ready for publication by October. These systems include Ti-Sc, V, Cr,

Y, Zr, Nb, Mo, Hf, Ta, and W. A bulletin, Alloy Phase Diagrams, will be

published; the first number is in proof, and the second in preparation.

During the current year, considerable progress has been made in the

development of software for on-line graphic display of phase diagram

data through application of spline fitting techniques to published phase

diagram data. The program now available plots camera ready, publication

quality phase diagrams, and has a user oriented input procedure. An

invited talk describing our progress in phase diagram graphics was presented at the 1980 CALPHAD meeting. Several groups expressed strong

interest in obtaining our program or in visiting NBS to make use of our graphics facilities. A database management program for the graphics

files is now under development. A Research Associate supported by ASM

has spent another summer with us, editing materials amassed under the

auspices of OSRD and other agencies for a comprehensive, complete revision

of the Hansen phase diagram compilation.

Of course, we are not attempting to evaluate all systems ourselves

at NBS. Evaluations will be carried out throughout the world at institutions recommended by the International Council. Priorities will determine

which important classes of systems are evaluated first. At NBS, we are

329
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Other experiments of fundamental significance to phase stability

are underway. Dr. David Goodman, a Postdoctoral Research Associate, is

investigating the thermodynamic properties of Ti-Al alloys using a solid

electrolyte electrochemical technique. Dr. R. C. Reno is spending a sabbatical year with us, and will be working on the application of the

positron annihilation technique to phase boundary determination in Ti

and Ti-Al alloys. An earlier collaborative study with Dr. Reno of

defects in Ti by the positron annihilation method was published this

year. Preliminary differential scanning calorimeter studies on Ti-Al,

directed at determination of the a/a - a 2 phase boundary, have been

carried out. Metallic glasses and metastable crystalline compounds are another class of material of great interest. They have often been found

to possess certain more desirable properties (e.g., corrosion resistance,

strength, hardness, and ductility) than their equilibrium counterparts.

In pursuit of this interest, a vacuum melt spinner is being constructed,

wherein the molten alloy is solidified very quickly by impinging the

liquid onto a copper wheel rotating at speeds around 10,000 rpm. By

this process, quenching rates on the order of 10 5 degrees/s are

typi cal

The major thrust of our theoretical studies in the current year has

been the use of electron band theoretical parameters in the prediction

of the heat of formation of binary alloys. The predictive scheme,

devised in collaboration with Dr. R. E. Watson, was described in a paper

published in Physical Review Letters this year. Two invited papers

describing this work were presented at the 1980 CALPHAD meeting. In

one, a database of enthalpies of formation for 60 of the 276 possible

binary pairs of transition elements was presented. In a second paper,

the experimental data were used for a constrained least squares adjustment

of the theoretical band parameters. Discrepancies between the resulting

predictions and the experimental data, where such data exists, are less

than the uncertainties in the data. The Proceedings of the Theory of

Alloy Formation organized and held at the New Orleans AIME meeting was

publ ished this year.

Prof. T. B. Massalski is visiting us this year. He serves as Chairman of the International Council's Panel on Binary Alloys, and

participates actively in our program. He has recently been elected to

the Polish National Academy of Sciences.

J. R. Cuthill has recently been made a Fellow both of the ASM and

the ASTM.

Our activity in ASTM continues. Task workers participate in ASTM

Committees D32 on Catalysis, E42 on Surface Analysis, El 3 on Molecular

Spectroscopy , B5 on Cu and Cu Alloys, and E7 on Nondestructive Evaluation.

L. H. Bennett serves as Chairman of the Committee on Alloy Phases of the

Metallurgical Society of AIME. L. H. Bennett and J. R. Cuthill are the

official NBS representati ves on the Joint ASTM-SAE Committee on the

Unified Numbering System in Metals and Alloys.

331
Alloys for Catalysis and Fuel Cells

Subtask 2 of Task 12145

A. J. McAlister

Development of successful fuel cells will significantly increase

the efficiency of fuel utilization and markedly reduce our national

dependence on foreign energy sources. For low temperature acid fuel

cells, a number of problems are performance limiting. Scarce and expensive

Pt, now used as both fuel and air catalysts should be replaced or more

efficiently used, and air catalyst supports more resistant to corrosion

at cathodic potentials are needed. Despite these difficulties, many

practical advances are being made. The DOD has successfully employed

small cells of a few kilowatt capacity in transportation and portable

power source applications, while in the area of power generation, DOE

and EPRI have sponsored a 4.8 megawatt, naptha fed assembly which is

scheduled for operation on the New York City power net this year.

Many challenging scientific problems are encountered in the area of

fuel cell research. In the past, we have focused our expertise in the

electronic and physical properties of refractory hard metals, compounds

of transition metals with light metalloids, on a search for acid stable,

hydrogen oxidation catalysts to substitute for Pt as the fuel electrocatalyst

in low temperature acid fuel cells. We observed, for the first time in our laboratory, some measure of activity and voltage stability in Re

metal, W0. 5 Ti 0. 5 C, and WP, and strong activity in the ternary MOi W C

(1 - x = 0.7, 0.8) which is i sostructural with the known strong, CO

poison-resistant fuel electrocatalyst WC.

Comparative studies of the Mo-rich ternary and WC have been completed.

We showed these alloys to be equally corrosion resistant, catalytical ly

active for H 2 oxidation, and CO tolerant. In addition, we demonstrated

that proton discharge is rate limiting on these carbides, in contrast to

Pt where chemisorptive dissociation is the slow step. This work has

been described in a paper accepted for publication in El ectrochemica

Acta, and in an invited talk at the symposium "Surface Properties of

Refractory Metals and Compounds," at the Annual AIME meeting.

Current activity focuses on anode catalysts of Pt dispersed on WC.

Pt, like chemically similar Co and Ni , is predicted to surface segregate

on WC, perhaps wetting it as well. Surface phases may form, and provide

not only more efficient use of Pt, but desirable catalytic properties

intermediate to those of highly active but CO sensitive Pt, and less

active but CO tolerant WC. We have prepared light loadings (nominal

partial monolayers) of Pt on WC. Studies in dilute H 3 P0 4 at 23°C show

these preparations to be about a tenth as active as similar loadings of

Pt on carbon supports in pure H 2 , but ten times as active as Pt sheet in

H 2 containing 2.9 percent CO. Triangular wave voltammetry and charging

curve measurements indicate very high dispersions; surface phase formation

is strongly indicated. This work was reported in an invited talk at the

1980 National Fuel Cell Seminar. Electrochemical and thermal stability

of these alloys are being investigated via polarization studies in

concentrated acid at high temperatures.

332
In our earlier survey studies of the refractory hard metals, we observed several materials, most notably TaN and TaB, to remain passivated

at potentials well beyond the 0 2 reduction equilibrium potential. We

are testing them for performance as non-corroding Pt cathode catalyst

supports.

Two experiments aimed at more thorough understanding of H 2 oxidation

on non-noble fuel electrocatalysts via el udi cation of the geometry of

the active sites are underway. In one, studies of H 2 oxidation on the

cubic W-Ti-C alloys as a function of metal content are being pursued, to

compare the mechanism of the hydrogen reaction with that on hexagonal

WC. (Pure TiC is inactive.)

In the other, Raman spectroscopy, which is capable of yielding

microscopic information on catalyst surfaces i_n si tu , is being pursued.

A Raman cell was completed and tested for chemical and optical performance.

Results of direct studies of WC in dilute H 3 P0 4 at 23 °C were negative.

Impurity modes may be observable on Pt/WC catalysts; several strongly

Raman active hydrocarbons are adsorbed on WC and may prove useful in

surface titration studies. These possibilities are being pursued.

A. J. McAlister is a member of ASTM Committees E42 on Surface

Analysis and D32 on Catalysis.

Nondestructive Evaluation of Nonuniformities in 2219 Aluminum Alloy Plate -- Relationship to Processing

Subtask 3 of Task 12145

L. J. Swartzendruber , L. K. Ives, W. J. Boettinger, S. R. Coriell, D. B. Ballard, D. E. Laughlin, R. B. Clough, F. S. Biancaniello, P. J. Blau,

J. W. Cahn, R. Mehrabian

This work was initiated at the National Bureau of Standards at the

request of the National Aeronautics and Space Administration. It was motivated by serious Government and aerospace industry concerns on the

possibility that substrength aluminum alloys may have been used in

aircraft and space vehicle structures. These concerns originated from

the discovery of "soft" spots in an anodized 2024-T851 aluminum alloy

machined part in June 1979. The part was machined from a ~ 14 cm (5.5 in.)

thick plate of the alloy produced at a particular manufacturing plant.

It was postulated that the "soft" spots were due to improper processing

of the plate. Furthermore, it was established that the same plant was producing a variety of other aluminum alloy plates including the 2219

aluminum alloy which was the subject of this investigation.

The aim of this work was to develop specific relationships between

processing variables used during ingot casting, working, and heat treatment

of the alloy, and the resulting microstructures, properties, and NDE

responses. This detailed blend of metallurgical examination of the

alloy with its NDE response is necessary not only to attack the specific

problem at hand but also to gain a fundamental knowledge of the features

of metallurgical mi crostructures which cause changes in NDE parameters.

333
We have focused primarily on eddy current testing (conductivity) for the

present but initial explorations into the use of ultrasonic measurements

(wave speed; attenuation) have also been conducted. Work in this program

is divided into five areas:

(1) Studies on as-received plate of 2219 aluminum alloy. This is

motivated by the realization that the properties vary across plate

thickness. These variations can have different effects on various NDE

techniques.

(2) Sol idification-Segergation Studies. Part of the variation in

properties across finished alloy plate is caused by segregation of the

alloy components (Cu, Mn) during ingot casting.

(3) Determination of time- temperature transformation diagrams

(C-curves) and the relationship between mechanical properties and conductivity.

Samples produced during various thermomechanical treatment have a wide

range of mechanical properties (hardness, yield strength, tensile strength)

and conductivity.

(4) Electron microscopy studies done on the wide range of metallurgical

microstructures produced. Extremely fine scale (~ 100 A) particles are responsible for the strength of aluminum alloys and contribute to associated

changes in conductivity.

(5) Predictions of heat flow conditions during malfunctions of the

commercial process, namely slow quenching from the solutionizing temperature;

and predictions using experimentally determined C-curves of the resultant

mechanical property degradations.

Conclusions reached in the study are listed below:

(1 ) As-received Plate

o Moderate variations in composition, hardness, electrical conductivity,

and mechanical properties were noted across the thickness of a 12.7 cm

(5 in.) thick 2219 aluminum alloy plate. Composition variations,

which influence measured conductivities, can be traced to the

original ingot. The variations in hardness and tensile properties

are mainly due to changes in cooling rate across the plate during

the quench and are probably influenced by inhomogeneous mechanical

deformation during processing.

(2) Solidification Segregation Studies

o Macrosegregation of copper in Direct Chill (DC) cast ingots of 2219

aluminum alloy cannot be completely eliminated by chill face scalping

and subsequent thermomechanical treatment. Macrosegregation does

remain in the finished plate product. However, good scalping

practice should limit copper content to above the solid solubility

limit with no deterioration in mechanical properties.

334
0 Elements with equilibrium partition coefficients less than unity

exhibit macrosegregation similar to copper while those with coefficients

greater than unity are opposite to copper. The magnitude of deviations

from the nominal are related to the deviation of the coefficient

from unity.

o The major phases present in cast 2219 aluminum alloy in this study

have been determined by electron microprobe analysis and electron

diffraction. They are a-aluminum solid solution, 0CuA 1 2 and Cu2 FeAl 7

. These phases are also present in the heat treated finished plate

product.

o Predictable macrosegregation has been obtained in laboratory ingots

of 2219 aluminum alloy. Both positive and negative segregation

similar to DC cast ingots are observed and are caused by the flow

of segregated interdendritic liquid, (figure 1)

o Electrical conductivity determined by eddy current measurements of

cast 2219 aluminum alloy is inversely related to copper content.

This fact complicates the relationship of conductivity to mechanical

properties used for nondestructive evaluation of the finished plate

product, (figure 1)

o Surface hardness and eddy current measurements may be very sensitive

to scalping depth in their ability to evaluate the condition of

finished alloy plate.

o Hardness, yield strength, and ultimate tensile strength of heat

treated 2219 aluminum alloys decrease significantly when the average

copper content drops below approximately 5.5 wt. %.

(3) C-Curve Determination and Relationship between Mechanical Properties

o No significant difference in either strength or hardness was detected

between alloys stretched between 5 and 7 percent permanent strain

during the thermomechanical processing of 2219 aluminum alloy.

o The functional form developed by Cahn and used previously by Staley

for 7075T6 and 6061T6 aluminum alloy was found to give an adequate

representation of the C-curves for 2219T87* if the form was modified

to include a minimum value for each property in question. Some

deficiency in this form at the highest and lowest temperatures was

noted.

o An efficient computer program was developed for using time-temperature

and property measurement data to establish C-curve parameters.

o For each heat treatment sequence, C-curves were determined for

hardness, yield strength, tensile strength, and electrical conductivity.

These C-curves can be used to determine the correlations between

335
. %

COPPER

(

Figure 1

.

Average copper content and electrical conductivity versus distance from

the bottom chill, in a unidirectionally solidified reduced cross section

laboratory ingot of 2219 aluminum alloy.

CONDUCTIVITY.

%

IACS

(-
these properties. C-curves could not be developed for elongation,

probably because this property is more sensitive to grain size and

other factors.

A small but significant difference was found between the C-curves

for sequence A (direct transfer to salt bath) and sequence B (water

quench and reheat in salt bath) type quenches. For a given salt

bath time and temperature, sequence B quenches resulted in a greater

degradation of mechanical properties.

The scatter in hardness and conductivity was found to be large.

This scatter can be expected to complicate NDE measurements and

should be properly taken into account when establishing NDE procedures

and specifications (see figures 2 and 3).

There is a great need for standardizing conductivity measurements

in order to bring about better i nterl aboratory agreement.

2219 aluminum alloy is, not as quench sensitive as some of the other

high strength aluminum alloys such as 7050.

(4) Electron Microscopy Studies

The agehardening response of 2219T87* and T851 is determined principally

by the formation of 0‘ precipitates with some contribution by 0"

precipitates.

An abnormal quench treatment which results in dwell times significant

with respect to the C-curves leads to the heterogeneous nucleation

and rapid growth of 0 and 0‘ precipitates.

The nucleation and growth behavior of the 0 and 0' precipitates

formed during an abnormal quench depend on the preexisting microstructural state of the material and on the thermal "path."

The large incoherent 0 and 0‘ precipitates formed during an abnormal

quench consume copper available from the matrix and thereby reduce

the concentration of 0‘ and 0" precipitates that contribute to

precipitation hardening during subsequent aging.

The C-curves are a measure of the concentration of large 0 and 0‘

precipitates formed during the quench treatment.

(5) Heat Flow Cal cul ations-~Property Predictions

Calculated plate properties, e.g., yield strength and hardness,

decrease monotonically with increasing distance from surface to

centerline of a plate for fixed heat transfer conditions.

For symmetric cooling and sequence (a) C-curves, the calculated

minimum yield strength (at the center of the plate) is 54.9, 53.7,

and 51.8 ksi for 2.54, 7.62, and 12.7 cm (1, 3, and 5 in.) thick

plates, respectively.

337
HARDNESS

US

CONDUCTIUITY

-

2219-T87*

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CROSSES CIRCLES

-1 _l

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VI

OJ *o

aj »— a

.s c

*-» *a •»- a> A3

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•*“ 3 O 3 *0

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+> .= a> "3

(C h >

*a a <u 5 -*“> i/> CJ

0) U o

> C -S

*-»O

3

> _

s- aj 3 ^3 +-> ^ •+« <+3 -a o c

c o o

o sj o t- o .r: +-> M fl

• LO iort >>0 *a > -3 3

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uo a) 3 +J "3 w

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J- T3 J3 3

a qj = u s. cr

CO o on

<4- +J O 00 4-> +J — 3 oO = 003

O oO OJ

i/> +-> r-

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S- !— -= 3

3 0) c. s- E

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O O s- 3

CO U 3 <4-

CM

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x<ro:ozujcnco zccm

338
ULTIMATE

TENSILE

STRENGTH

US

HIACS -

2219-T87*

i- -a 2 a

ia v) M <T3

—

<g *a f— -y "3 3 -C

a> > -m >>— i» ^*--3 > a • u -M +J (/I £•!• u a ii <4- 3 > *a T3 i. -r- (J o u u C 4-1 8

<0 • *a

<41

O rg > -= LO 3 _

+» ci c

ti >>

C5 W> Cl-Q -—- (U — s. c -c -a ,-a s- U> C 3

4-> 4-) ,-g cr

W)

J

J

W

T—

ai -3 i_ 4-> <— i> a wi •i— i. 4-> .-g lo a. a» w flr- J (rt U

+»

C <41 !3 o <+- **- 3) £ 0 4->^o

<C 4-* i.

C <4- o u a>

s_ ”ac

(41 •!— 3. CJ o = a c 4-» O _3 •*“ o

-5 «-> «— o

i-i_8

CO

aii.3

Cl

>~»z: ari-Ld hujz^«-*ju

339
o For asymmetric cooling and sequence (A) C-curves, the calculated

minimum yield strength (at the bottom surface of the plate) is 54.4,

50.7, 45.9 ksi for 2.54, 7.62, 12.7 cm (1, 3, and 5 in.) thick plates,

respecti vely.

o For plate thicknesses greater than 2.54 cm, sequence (b) C-curves

yield lower properties values than sequence (A) C-curves. For example,

for asymmetric cooling and sequence (B) C-curves the calculated minimum

yield strength is 54.6, 48.0, 41.5 ksi for 2.54, 7.62, and 12.7 cm

(1, 3, and 5 in.) thick plates, respectively.

o Interrupted (abnormal) cooling, in which the heat transfer coefficient

at the bottom surface changes from the same value as at the top surface

to a zero value, can result in lower property values than found for

asymmetric cooling. For example, for a 12.7 cm (5 in.) thick plate

and sequence (B) C-curves interrupted cooling yields a minimum yield

strength of 39.0 ksi compared with 41.5 ksi for asymmetric cooling.

Work in this program will continue in three general areas. A round

robin of conductivity measurements at various laboratories has been conducted

on NBS-prepared 2219 aluminum alloys in various heat-treated conditions.

This work may lead to a set of aluminum alloy conductivity standards.

Second, controlled ultrasonic measurements are being planned for pure Al-Cu

precipitation hardened alloys. Thirdly, a program has been initiated to

investigate the relationship of processing to NDE response of 2024 aluminum

alloy. This alloy appears to be more sensitive to heat-treating practice

than 2219 aluminum alloy.

Other Activities of the

Metallurgy Division

Invited Tal ks

The Signal -to-Noi se Criterion and Its Implementation as a Generalization

of the SVD

International Symposium on 111 Posed Problems: Theory & Practice

University of Delaware, Newark, Delaware

J. A. Simmons and D. F. O'Leary

October 2, 1979

Solid Particle Erosion Mechanisms in Metals

University of Delaware, Newark, Delaware

A. W. Ruff

October 4, 1979

Pin and V-Block and B1 ock-on-Ri ng Bench Wear Tests for Engine Oil

Eval uation

NBS Conference on Measurement Standards for Recycled Oil/Systems

Performance and Durability, Washington, DC

L. K. Ives

October 23, 1979

Diffusion and Mass Transport Phenomena in Copper and Copper Alloys

Allegmeine Elektricitats-Gesel 1 schaft, Frankfurt, West Germany

D. B. Butrymowicz

November 12, 1979

Data Evaluation in the NBS Diffusion in Metals Data Center

Academy of Sciences of the USSR, Moscow, USSR

D. B. Butrymowicz

November 14, 1980

Grain Boundary Diffusion

Academy of Sciences of the USSR, Moscow, USSR

D. B. Butrymowicz

November 15, 1979

Diffusion - Induced Grain Boundary Migration

Academy of Sciences of the USSR, Moscow, USSR

D. B. Butrymowicz

November 16, 1979

The NBS Diffusion in Metals Data Center

Academy of Sciences of the USSR, Moscow, USSR

D. B. Butrymowicz

November 20, 1979

Diffusion in Grain Boundaries in Metals

Academy of Sciences of USSR, Kharkov, USSR

D. B. Butrymowicz

November 22, 1979

342
The NBS Diffusion in Metals Data Center

Academy of Sciences of USSR, Kharkov, USSR

D. B. Butrymowicz

November 23, 1979

Diffusion-Induced Migration of Grain Boundaries in Metals

Academy of Sciences of the USSR, Kharkov, USSR

D. B. Butrymowicz

November 23, 1979

Data Evaluation in the NBS Diffusion in Metals Data Center

Academy of Sciences of the USSR, Kharkov, USSR

D. B. Butrymowicz

November 26, 1979

Numerical Data Evaluation Procedures in the NBS Diffusion in Metals

Data Center

Academy of Sciences of the USSR, Kiev, USSR

D. B. Butrymowicz

November 28, 1979

Grain Boundary Diffusion in Metals

Academy of Sciences of the USSR, Kiev, USSR

D. B. Butrymowicz

November 29, 1979

Diffusion- Induced Grain Boundary Migration in Metals

Academy of Sciences of the USSR, Kiev, USSR

D. B. Butrymowicz

November 30, 1979

The NBS Diffusion in Metals Data Center

Academy of Sciences of the USSR, Kiev, USSR

D. B. Butrymowicz

November 30, 1980

Models and Analytic Mechanisms for the Testing of Diffusion Data

Trans Tech SA, Aedermannsdor , Switzerland

D. B. Butrymowicz

December 6, 1979

Corrosion and Fatigue of Surgical Implant Metals

The Johns Hopkin*s University, Baltimore, Maryland

Anna C. Fraker

February 12, 1980

Reproducible Acoustic Emission by Indentation in Steels

Third International Conference on NDE in the Nuclear Industry,

Salt Lake City, Utah

R. B. Clough and J. A. Simmons

February 13, 1980

343
Hydrogen Oxidation on Mo-W Carbide Alloy Catalysts

Annual AIME Meeting, Las Vegas, Nevada

A. J. McAlister and L. H. Bennett

February 25, 1980

Solutal Convection Effects

Marshall Space Flight Center, Huntsville, Alabama

W. J. Boettinger

March 5, 1980

Reflection Topography of Subgrain Misorientation

U.S. -France Cooperative Science Program, Paris, France

M. Kuriyama

March 12, 1980

Czochralski Growth of Ni Single Crystals

U.S. -France Cooperative Science Program, Paris, France

M. Kuriyama

March 13, 1980

Oblique Magnetic Domain Walls in Nickel

U.S. -France Cooperative Science Program, Paris, France

M. Kuriyama

March 14, 1980

Surface Tension Measurements of Gallium

Marshall Space Flight Center, Huntsville, Alabama

S. C. Hardy

March 20, 1980

X-Ray Topography: Dynamical Diffraction for Imperfect Crystals

Universitat Dortmund, Dortmund, Germany

M. Kuriyama

March 21, 1980

Interface Stability During Rapid Solidification

Second International Conference on Rapid Solidification Processing,

Res ton, Virginia

S. R. Coriell

March 24, 1980

Rapid Solidification Processi ng--An Outlook

Second International Conference on Rapid Solidification Processing,

Reston, Virginia

R. Mehrabian

March 24, 1980

Mechanisms of Solid Particle Erosion

Engineering Foundation Meeting, Asilomar, California

A. W. Ruff

March 24, 1980

344
Microstructural Studies of Copper Alloys and Steels After Sliding Wear

Cornell University, Ithaca, New York

A. W. Ruff

April 8, 1980

Materials Processing—A Solidification Processing Perspective of

the Field

1980 Burgess Memorial Lecture, ASM, Washington, DC

R. Mehrabian

April 14, 1980

Theory and Experiments in Acoustic Emission

Stanford University, Palo Alto, California

J. A. Simmons

April 15, 1980

Acoustic Emission: Theory and Experiments

Lawrence Livermore Laboratory, Livermore, California

J. A. Simmons

April 17, 1980

Focusing Arrangements and Crystals for Laboratory EXAFS

University of Washington, Seattle, Washington

G. G. Cohen

April 28, 1980

Gating Practice in Die Casting

American Die Casting Institute, Chicago, Illinois

R. Mehrabian

April 31, 1980

Hard Surfacing for Valve Applications

University of Wisconsin, Madison, Wisconsin

K. J. Bhansali

May 20, 1980

A Database for Enthalpies of Formation of Binary Transition Metal Alloys

CALPHAD Conference, Montreal, Canada

L. H. Bennett and R. E. Watson

May 26, 1980

Optimized Predictions for Heats of Formation of Transition Metal Alloys

CALPHAD Conference, Montreal, Canada

R. E. Watson and L. H. Bennett

May 27, 1980

Interactive Computer Graphics for Storing Phase Diagrams

CALPHAD Conference, Montreal, Canada

J. L. Murray and D. J. Orser

May 28, 1980

345
A New Technique for Calculating Near Field Elastic Wave Propagation in

a Plate National Meeting of the Society for Industrial and Applied

Mathematics

,

Alexandria, Virginia

J. A. Simmons and J. R. Willis

June 5, 1980

Convective and Interfacial Instabilities During Directional Solidification

Twenty-Third COSPAR Conference, Budapest, Hungary

S. R. Coriell

June 9, 1980

Influence of Nickel on Galling Resistance of Cobalt Base Alloys

Gordon Research Conference, New London, New Hampshire

K. J. Bhansali

June 9, 1980

Solid Particle Erosion of Metals and Ceramics:

Wear Deformation Processes on Steels

Gordon Conference on Friction, Lubrication and

New Hampshire

A. W. Ruff

June 10, 1980

Origin and Characterization of Acoustic Emission in Metals

DARPA Materials Research Council, La Jolla, California

H. Wadley

July 11, 1980

Theory and Experiments on Acoustic Emission

DARPA Materials Research Council, La Jolla, California

J. A. Simmons

July 11, 1980

Theory of Acoustic Emission

DARPA/AFML Review of Progress in Quantitative NDE, La Jolla, California

J. A. Simmons and R. B. Clough

July 14, 1980

Ternary Alloys of Tungsten Carbide for Fuel Catalysts in Acid Fuel Cells

National Fuel Cell Seminar, San Diego, California

A. J. McAlister, L. H. Bennett and M. I. Cohen

July 15, 1980

Low Temperature Heat Capacity of Metallic Glasses

Reactor Radiation Division Meeting, National Bureau of Standards,

Washington, DC

R. D. Shull

July 24, 1980

Convective and Interfacial Instabilities During Unidirectional

Solidification of a Binary Alloy

Engineering Foundation Conference, Rindge, New Hampshire

S. Coriell

August 7, 1980

Observations of Sliding

Wear, New London,

346
Technical and Professional Committee Participation and Leadership

American Association for Crystal Growth

R. L. Parker, Executive Committee

j American Foundrymen's Society

R. Mehrabian, Member

American Institute of Metallurgical Engineers

Solidification Committee of the Metal lurgical Society

W. J. Boettinger, Chairman

S. R. Coriell, Secretary

R. Mehrabian, Member

R. J. Schaefer, Member

Electronic Materials Committee of the Metallurgical Society

R. L. Parker, Member

I Alloy Phases Committee of the Metallurgical Society

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, Executive Committee, Washington Chapter

A. C. Fraker, Chairperson, Washington Chapter

A. W. Ruff, Program Committee, Washington Chapter

R. Mehrabian, Member, Washington, Chapter

Mass Transport Activity

J. R. Manning, Member '

Process Modeling Activity

J. R. Manning and R. Mehrabian, Members

American Society for Metals/American Institute of Metallurgical Engine

Composite Committee

R. Mehrabian, Member

International Council for the ASM/NBS Program for Alloy Phase

Diagrams

L. H. Bennett and J. R. Cuthill, Members

Handbook Committee on Definitions

J. R. Cuthill, Member

American Society of Mechanical Engineers

Research Committee on Lubrication (Hardfacing and Coatings)

K. J. Bhansali, Member

American Society of Mechanical Engineers/American Society for Metals

Wear of Materials Conference Committee, 1981

A. W. Ruff, Program Chairman

347
American Society for Testing and Materials

Al: Steel, Stainless Steel, Related Alloys; Castings

R. L. Parker, Member

B5: Copper and Copper Alloys; Methods of Test

L. J. Swartzendruber , Member

B6: Die-Cast Metals and Alloys

R. Mehrabian, Chairman

B7: Light Metals and Alloys; Aluminum Alloy Ingots and Castings

W. J. Boettinger, Member

D32: Catalysts

A. J. McAlister, Member

E4: Metallography

L. J. Swartzendruber and P. J. Blau, Members

E42: Surface Analysis

J. R. Cuthill, Chairman

A. J. McAlister, Member

E4. 11.07: Metallography; Electron Metallography;

Scanning Electron Microscopy

D. B. Ballard, Task Group Leader

E7: Nondestructive Testing

L. H. Bennett and L. J. Swartzendruber , Members

E7.04: Acoustic Emission

J. A. Simmons and R. B. Clough, Members

E7.04: Joint Task Group on Acoustic Emission; Sensitivity

Cal ibration

J. A. Simmons, Chairman

F4: Medical and Surgical Materials and Devices

A. C. Fraker, Member

F4/G1: Joint Section on Corrosion of Implants

A. C. Fraker, Co-Chairperson

G2: Erosion and Wear

A. W. Ruff, Vice Chairman

G2.2: Solid Particle Erosion

A. W. Ruff, Task Group Leader

K. J. Bhansali, Member

348
American Society for Testing and Materials

A1 : Steel, Stainless Steel, Related Alloys; Castings

R. L. Parker, Member

B5: Copper and Copper Alloys; Methods of Test

L. J. Swartzendruber, Member

B6: Die-Cast Metals and Alloys

R. Mehrabian, Chairman

B7: Light Metals and Alloys; Aluminum Alloy Ingots and Castings

W. J. Boettinger, Member

D32: Catalysts

A. J. McAlister, Member

E4: Metallography

L. J. Swartzendruber and P. J. Blau, Members

E42: Surface Analysis

J. R. Cuthill, Chairman

A. J. McAlister, Member

E4. 11.07: Metallography; Electron Metallography;

Scanning Electron Microscopy

D. B. Ballard, Task Group Leader

E7: Nondestructive Testing

L. H. Bennett and L. J. Swartzendruber , Members

E7.04: Acoustic Emission

J. A. Simmons and R. B. Clough, Members

E7.04: Joint Task Group on Acoustic Emission; Sensitivity

Cal ibration

J. A. Simmons, Chairman

F4: Medical and Surgical Materials and Devices

A. C. Fraker, Member

F4/G1: Joint Section on Corrosion of Implants

A. C. Fraker, Co-Chairperson

G2: Erosion and Wear

A. W. Ruff, Vice Chairman

G2.2: Solid Particle Erosion

A. W. Ruff, Task Group Leader

K. J. Bhansali, Member

349
G2.91: Terminology and Definitions

L. K. Ives, Chairman

P. J. Blau, Vice Chairman

Applied Mechanics Reviews

R. B. Clough, Member, Review Staff

Society for Biomaterials Standards Committee

A. C. Fraker, Chairperson

US-USSR Joint Committee on Electrometal 1 urgy

R. L. Parker, Member

US-USSR Technology Exchange Agreement, Sub-committee on Electro-Slag

Remel ti ng

R. Mehrabian, Member

Florence Review Committee, Review of Scanning Electron Microscopes

D. B. Ballard, Chairman

International Council on Alloy Phase Diagrams

R. Mehrabian, Member

International Journal of Crystal Growth

R. L. Parker, Deputy Principal Editor, Editorial Board

International Organization of Crystal Growth

R. L. Parker, Council Member

International Journal of Diffusion and Defect Data

D. B. Butrymowicz, Advisory Board Member

International Conference on Rapid Solidification Processing, 1980

R. Mehrabian, Chairman

International Council of Science Unions, Committee on Space Research (COSPAR)

R. L. Parker, Member

Maryland Institute of Metals

W. J. Boettinger, Executive Board Member

Materials Processing Center, Massachusetts Institute of Technology

R. Mehrabian, Member Advisory Board

Visiting Committee of Metallurgy and Materials Science Department of

Carnegie-Mel 1 on 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. Coriel 1, Member

350
National Aeronautics and Space Administration Steering Committee,

Materials Processing in Space Panel, Supporting Research and

Technology Subcommittee

J. R. Manning, Member

National Aeronautics and Space Administration, Universities Space

Research Association

R. Mehrabian, Member

National Conservation Advisory Council

H. C. Burnett, Member

Third International Conference on NDE in the Nuclear Industry

R. B. Clough, Organizing Member and Acoustic Emission Session Chairman

Fifth International Conference on NDE in the Nuclear Industry

R. B. Clough, General Chairman

National Materials Advisory Board, Committee on Aluminum Powder Alloys

J. R. Manning, Member

National Materials Advisory Board, Committee on Superalloy Powder Alloys

R. Mehrabian, Member

National Materials Advisory Board, Committee on Amorphous and

Metastable Materials

R. Mehrabian, Member

National Materials Advisory Board, Committee on Materials Substitution

Methodology

R. Mehrabian, Liaison Member

National Science Foundation, Facilities Subcommittee of the Materials

Research Advisory Committee

G. G. Cohen, Member

Society of Automotive Engineers/American Society of Testing and Materials

Unified Numbering System for Metals and Alloys

J. R. Cuthill, Alternate Representative

L. H. Bennett, Member

Society of Rheology

R. Mehrabian, Member i

i

351
Publ i cations

Rapid Solidification

J. W. Cahn, S. R. Coriel 1, and W. J. Boettinger

Proceedings of the Laser and Electron Beam Processing of Materials

Conference, Materials Research Society (1979)

Consolidation of Plasma-Sprayed Coatings by Laser Remelting

J. D. Ayers and R. J. Schaefer

SPIE , 198, 57-64 (1979)

Heats of Formation of Transition Metal Alloys

R. E. Watson and L. H. Bennett

Phy. Rev. Letters, 43, 1130 (1979)

Positron Annihilation Study of Defects in Titanium

R. C. Reno, L. J. Swartzendruber , and L. H. Bennett

NDT International, 224, (1979)

A Study of Deformation and Fracture Processes in a Low-Alloy Steel by

Acoustic Emission of Transient Analysis

H. N. G. Wadley and C. B. Scruby

Acta Met., 27, 613-625, (1979)

Eddy-Currents in a Conducting Cylinder with a Crack

R. D. Spal and A. H. Kahn

J. Appl . Phys. , 50, 6135 (1979)

Superconductivity in Hg 3 AsF6

: Absence of Surface Mercury

R. D. Spal, C. -E. Chen, A. Denenstein, A. R. McGhie, A. J. Heeger,

and A. G. MacDiarmid

Solid State Commun. , 32, 641 (1979)

X-ray Scattering Study of One-Dimensional Lattice Dynamics in Hg 3 AsF 6

R. D. Spal, C. -E. Chen, and A. J. Heeger

Phys. Rev. B, 2]_, 3110 (1979)

Absence of Localization in a Quasi-One-Dimensional Metal:

Magnetoresistance of Hg 3 AsF6

D. P. Chakraborty, R. D. Spal, A. M. Denestein, K. -B. Lee, A. J. Heeger,

and M. Ya. Azbel

Phys. Rev. Letter, 43, 1832 (1979)

Pin and V-Block and B1 ock-on-Ri ng Bench Wear Test for Engine Oil

Eval uation

L. K. Ives and P. A. Boyer

Proceedings of the Joint Conference on Measurement Standards for

Recycled Oil/Systems Performance and Durability (1979)
Corrosion Fatigue of 3 1 6 L Stainless Steel, Co-Cr-Mo Alloy and ELI

Ti-6A1-4V

M. A. Imam, A. C. Fraker, and C. M. Gilmore

ASTM Spec. Tech. Pub. 684, 128-143 (1979)

Thixoforging of Aluminum Alloys

C. Y. Chen, J. A. Sekhar, D. G. Backman, and R. Mehrabian

Materials Science and Engineering, 40, No. 2, 265-272 (1979)

The Interface Phase in Al-Mg/Al 2 0 3 Composites

A. Munitz, M. Metzger, and R. Mehrabian

Metallurgical Transactions A, 10A , 1491 (1979)

Convective and Interfacial Instabilities During Directional Solidification

S. R. Coriell, M. R. Cordes, W. J. Boettinger, and R. F. Sekerka

Proc. of Twenty-Third COSPAR (Committee on Space Research) Plenary Meeting,

Budapest, Hungary (1980)

Laser Surface Melting with Carbide Particle Injection

R. J. Schaefer, T. R. Tucker, and J. D. Ayers

in Laser and Electron Beam Processing of Materials edited by

C. W. White and P. S. Peercy, Academic Press, 754-759 (1980)

Consolidation of Metal Coatings by Electron Beam Melting

T. R. Tucker, J. D. Ayers, and R. J. Schaefer

in Laser and Electron Beam Processing of Materials edited by

C. W. White and P. S. Peercy, Academic Press, 760-765 (1980)

The Generation of Clean Liquid Gallium Surfaces

J. Fine, S. C. Hardy, and T. D. Andreadis

Symposium on the Physics of Ionized Gases, Dubrovnik, Yugoslavia (1980)

Basic Mechanisms of Atomic Redistribution in Alloys Undergoing

Irradi ati on

J. R. Manning

Proc. of Symposium on Irradiation Phase Stability (1980)

Mossbauer Spectroscopy of Polycrystalline Steel Fibers

D. S. Lashmore, L. J. Swartzendruber , and L. H. Bennett

Applied Physics Letters, 36, 39 (1980)

Parameters in Semi-empirical Theories of Alloy Phase Formation

L. H. Bennett and R. E. Watson

in Theory of Alloy Phase Formation edited by L. H. Bennett

(The Metallurgical Society of AIME, New York) 390 (1980)

353
What's Special About Transition Metals in Alloys?

R. E. Watson and L. H. Bennett

in Theory of Alloy Phase Formation edited by L. H. Bennett

(The Metallurgical Society of AIME, New York) 425 (1980)

Tunable Laboratory EXAFS System

G. G. Cohen, D. A. Fischer, J. Colbert, and N. J. Shevchik

Rev. Sci. Inst., 5J_ , 273-277 (1980)

EXAFS Investigation of Oxidation Processes in Metallic Cu

D. A. Fischer, G. G. Cohen, and N. J. Shevchik

J. Phys. F: Metal Phys. , 10, L139-L142 (1980)

X-ray Residual Stress Evaluation by an Energy Dispersive System

M. Kuriyama, W. J. Boettinger, and H. E. Burdette

Proc. of Symposium on Accuracy in Powder Diffraction,

NBS Spec. Pub. 567, 479-487 (1980)

Energy Dispersive XRF Composition Profiling Using Crystal Collimated

Incident Radiation

W. J. Boettinger, H. E. Burdette, and M. Kuriyama

Advances in X-ray Analysis, 23, 209-217 (1980)

Crystal Subgrain Misorientations Observed by X-ray Topography in

Ref 1 ecti on

R. W. Armstrong, W. J. Boettinger, and M. Kuriyama

J. Appl . Phys., 13, 223-230 (1980)

Degradation of Solar Coatings Observed by Scanning Electron Microscopy

M. A. Post and D. Ballard

J. Coatings Technology, 52, 55-62 (1980)

Thickness of Gold Coatings Measured with a Calibrated SEM

F. Ogburn and D. Ballard

Platings and Surface Finishing, 49-53 (1980)

Electroforming a Micrometer Scale of 50 pm (2 mil) Overall Length

J. Young, F. Ogburn and D. Ballard

Metal Finishing (1980)

Debris Analysis of Erosive and Abrasive Wear

A. W. Ruff

Proc. of the International Conference of Fundamentals of Tribology (1980)

354
Low Cobalt Base Hardfacing Alloys

K. J. Bhansali, A. J. Hickl, and W. L. Silence

Welding Design and Fabrication (1980)

Corrosion and Corrosion-Fatigue Behavior of Ti-4.5Al~5Mo-l.5Cr

(Corona 5) and Ti-6A1-4V

M. A. Imam, A. C. Fraker, K. M. Speck, and C. M. Gilmore

Proc. of Fourth International Conference on Titanium, Kyoto, Japan (1980)

Use of a Two Diagonal Measurement Method for Reducing Scatter in Knoop

Microhardness Testing

P. J. Blau

Scripta Met., 14, 719-724 (1980)

Heat Flow in Atomized Metal Droplets

C. G. Levi and R. Mehrabian

Met. Trans. B, TJB, 21 (1980)

Rapid Melting and Solidification of a Surface Due to a Stationary

Heat Flux

S. C. Hsu, S. Kou, and R. Mehrabian

Met. Trans. B, TJB, 29 (1980)

Heat Flow Limitations in Rapid Solidification

R. Mehrabian, S. C. Hsu, S. Kou, and C. G. Levi

in Recent Advances in Metals Processing , edited by R. Mehrabian,

J. J. Burke and V. Weiss

Plenum Publishing Corp. , New York (1980)

Unifying Aspects of Metals Processing

M. C. Flemings and R. Mehrabian

in Recent Advances in Metals Processing , edited by R. Mehrabian,

J. J. Burke, and V. Weiss

Plenum Publishing Corp., New York (1980)

Electrohydrodynamic Techniques in Metals Processing

J. Perel , J. F. Mahoney, B. E. Kalensher, K. E. Vickers and R. Mehrabian

in Recent Advances in Metals Processing , edited by R. Mehrabian,

J. J. Burke, and V. Weiss

Plenum Publishing Corp., New York (1980)

Solidification-Segregation Modeling in ESR Ingots

D. R. Poirier, M. C. Flemings, R. Mehrabian, and H. J. Klein

in Recent Advances in Metals Processing , edited by R. Mehrabian,

J. J. Burke, and V. Weiss

Plenum Publishing Corp., New York (1980)

355
Bulletin of Alloy Phase Diagrams

L. H. Bennett, Editor

American Society for Metals, Metals Park, 1_, No. 1 (1980)

Rapid Solidification Processi ng--An Outlook

M. Cohen, B. H. Kear, and R. Mehrabian

in Rapid Solidification Processing: Principles and Technologies II , (to be publ ished)

Interface Stability During Rapid Solidification

S. R. Coriell and R. F. Sekerka

in Rapid Solidification Processing: Principles and Technologies II (to be published)

Eutectic Solidification and the Formation of Metallic Glasses

W. J. Boettinger, F. S. Biancaniello, G. M. Kalonji and J. W. Cahn

in Rapid Solidification Processing: Principles and Technologies II , (to be publ i shed)

:\ - Solutal Convection Induced Macrosegregation and the Dendrite to Composite

Transition in Off-Eutectic Alloys

W. J. Boettinger, F. S. Biancaniello, and S. R. Coriell

Met. Transactions A, (to be published)

Convective and Interfacial Instabilities During Unidirectional

Solidification of a Binary Alloy

S. R. Coriell, M. R. Cordes, W. J. Boettinger, and R. F. Sekerka

Journal of Crystal Growth, (to be published)

Electro-Oxidation of Hydrogen on Mo-W Carbide Alloy Catalysts in

Acid Electrolytes

A. J. McAlister and M. I. Cohen

El ectrochimica Acta, (to be published)

Acoustic Emission for the Physical Examination of Metals

H. N. G. Wadley, C. B. Scruby, and J. H. Speake

International Metals Review, (to be published)

Crystals and Focusing Arrangements for Laboratory EXAFS

G. G. Cohen and R. Deslattes

Proceedings of Workshop on Laboratory EXAFS Facilities, (to be published)

Reproducible Acoustic Emission by Indentation in Steels

R. B. Clough and J. A. Simmons

Materials Evaluation Research Supplement, (to be published)

356
A DC Method of Measuring the Magnetoconductivity Tensor in Anisotropic

Crystal

s

R. D. Spal

J. Appl. Phys. , (to be published)

A Bi di agonal ization-Regularization Procedure for Large Scale Discretizati

of Ill-Posed Problems

D. P. O'Leary and J. A. Simmons

SIAM Journal of Computing, (to be published)

Wear Coefficients for Hardfacing Alloys

K. J. Bhansali

Wear Control Handbook, ASME, (to be published)

Anodic Polarization Behavior of Ti-Ni and Ti-6A1-4V in Simulated

Physiological Solutions

K. M. Speck and A. C. Fraker

Journal of Dental Research, (to be published)

Emerging Concepts Explain Wear Metal 1 urgical ly

P. J. Blau

Materials Engineering, (to be published)

Rapid Melting and Solidification of a Surface Due to a Moving Heat Flux

S. Kou, S. C. Hsu, and R. Mehrabian

Met. Trans., (to be published)

A New Method for Fabrication of Aluminum - Alumina Composites

B. F. Quigley, G. J. Abbaschian, R. Wunderlin, and R. Mehrabian

Met. Trans., (to be published)

Wear Resisting Surfaces by Carbide Particle Injection

J. D. Ayers, T. R. Tucker, and R. J. Schaefer

in Rapid Solidification Processing: Principles and Technologies II , (to be published)

357
Division Seminars

The Role of Electron Band Theory in the Prediction of Phase Diagrams

R. E. Watson

Brookhaven National Laboratory, Upton, New York

October 24, 1979

Challenges and Opportunities for Nondestructive Inspection Technology

in the High Volume Consumer Goods Industries

E. P. Papadakis

Ford Motor Company, Detroit, Michigan

November 19, 1979

A Comparison of Experiment and Theory of Continuous Ordering

H. Chen

University of Illinois at Urbana-Champaign, Urbana, Illinois

December 14, 1979

Comparison of Electron and Laser Surface Melting in the Preparation

of Tool Steels

P. Strutt

University of Connecticut, Storrs, Connecticut

January 15, 1980

Effect of Microstructure on Properties of a + p Ti Alloys

J. C. Williams

Carnegie-Mel Ion University, Pittsburgh, Pennsylvania

January 17, 1980

Hydrogen Related Fracture Mechanisms

H. K. Birnbaum

University of Illinois at Urbana-Champaign, Urbana, Illinois

January 23, 1980

Sealing Laws in Solidification

M. E. Glicksman

Rensselaer Polytechnic Institute, Troy, New York

March 7, 1980

Vacancies

K. Lucke

Insti tute

March 10,

and Kinetics of Ordering Processes in Alloys

fur Allgemune Metal lkunde and Metal! physik, Aachen, West Germany

1980

Design and Wear Testing of a Continuous Fiber/Particulate Composite

Total Surface Hip Replacement

J. Roberts

Rensselaer Polytechnic Institute, Troy, New York

March 18, 1980

358
Recent Developments in the State Variable Description of

Nonelastic Deformation

M. Jackson

Cornell University, Ithaca, New York

March 19, 1980

VAR—The Vacuum Arc and Metal Transfer

F. J. Zanner

Sandia National Laboratories , Albuquerque, New Mexico

March 21 , 1980

Development of Superplastic Microstructures and Microstructure-Property

Relations

0. D. Sherby

Stanford University, Stanford, California

March 28, 1980

Analysis of Instability Phenomena During the RF Heating and

Melting of Ceramics

R. F. Sekerka

Carnegi e-Mellon University, Pittsburgh, Pennsylvania

April 18, 1980

Digital Image Processing, A Personal Account, from SEM to RPV

M. Oron

Stanford University, Stanford, California

April 29, 1980

New Results and Open Mathematical Questions in Modeling the

Interactions of Pores and Grain Boundaries in Metals

R. L. Coble

Massachusetts Institute of Technology, Cambridge, Massachusetts

May 21, 1980

Ultrasonic Measurement of Solid/Liquid Interface Position

R. L. Parker

National Bureau of Standards, Washington, DC

May 27, 1980

Ultrasonic Studies of Defects in Irradiated Metals

K. Holtman

University of Illinois, Urbana, Illinois

June 19, 1980

The Use of Positron Annihilation in Metal Physics

S. Berko

Brandeis University, Waltham, Massachusetts

June 17, 1980

359
Aluminum Rapid Solidification Alloy Processes

W. S. Cebulak

Alcoa Laboratories, Alcoa Center, Pennsylvania

June 19, 1980

A Variational Approach for Waves in Random Composites

J . Wi 11 i

s

Atomic Energy Research Establishment, Harwell, United Kingdom

July 1, 1980

Dual Phase Steels

M. S. Rashid

General Motors Technical Center, Warren, Michigan

July 29, 1980

External Recognition

IR-100 Award on X-ray Magnifiers

1979

W. J. Boettinger, H. C. Burdette, and M. Kuriyama

NBS EEO Annual Individual Award

November 1979

G. J. Mattamal (joint with R. B. Johnson)

Johns Hopkins University Citation

Student Coop Program with NBS

June 1980

G. J. Mattamal

Books

Theory of Alloy Phase Formation

Edited by L. H. Bennett

The Metallurgical Society of AIME, New York

1980

Rapid Solidification Processing: Principles and Technologies II

Edited by R. Mehrabian, B. H. Kear and M. Cohen

Claitor's Publishing Division, Baton Rouge, Louisiana

1 980

Special Reports

NBS: Materials Measurement

J. R. Manning

NBSIR 80-2082

Analysis of Erosion-rel ated Failure Information from Coal Gasification

Systems

A. W. Ruff

NBS Report 80-2045

360
Studies of Microscopic Aspects of Wear Processes in Metals

A. W. Ruff and P. J. Blau

NBS Report 80-2058

Nondestructive Evaluation of Nonuniformities in Aluminum Alloy Plate

L. J. Swartzendruber, L. K. Ives, W. J. Boettinger, R. B. Clough,

S. R. Coriell, P. J. Blau, J. W. Cahn, and R. Mehrabian

NBS Special Report to NASA (1980)

Nondestructive Evaluation of Nonuniformities in 2219 Aluminum Alloy

Plate—Relationship to Processing

L. J. Swartzendruber , L. K. Ives, W. J. Boettinger, S. R. Coriell,

D. B. Ballard, D. E. Laughlin, R. B. Clough, F. S. Biancaniel 1 o

,

P. J. Blau, J. W. Cahn, and R. Mehrabian

Technical Report to National Aeronautics and Space Administration,

Washington, DC (1980)

Standard Reference Materials

Supplied Office of Standard Reference Materials with 150 units of

SRM-469 and issued 54 units of SRM-484.

An electron microprobe standard reference material (Fe-Cr-Ni alloy)

was produced by F. S. Biancaniel lo, P. A. Boyer, and A. W. Ruff of the

Metallurgy Division cooperatively with the Center for Analytical

Chemistry. This SRM represents a composition standard used on the

micrometer scale of homogeneity in many analytical laboratories in

the U.S. and abroad. The first production lot of this SRM was sold

out requiring the production and certification of a second lot of

materi al

.

Patents

Acoustic Embrittlement Detector

R. B. Clough and R. Fields

NBS Cast No. 1845

August 5, 1980

Nickel Base Wear Resistant Alloy

K. J. Bhansali

January 1, 1980

U.S. Patent 4,181 ,523

Sponsored Conferences

Measurement and Standards for Recycled Oil/Systems Performance and

Durabi 1 ity

NBS, Gaithersburg, Maryland

October 23-26, 1979

A. W. Ruff, Co-Chairman

361
Second International Conference on Rapid Solidification Processing:

Principles and Technologies

Reston, Virginia

March 23-26, 1980

R. Mehrabian, Chairman

Failure Prevention in Ground Transportation System

NBS, Gaithersburg, Maryland

April 22-24, 1980

A. W. Ruff, Organizing Committee

Implant Retrieval: Material and Biological Analysis

NBS, Gaithersburg, Maryland

May 1-3, 1980

A. W. Ruff, Co-Chairman

A. C. Fraker, Organizing Committee

362

iniiiimiiiiiiiii ii i miiiiiiii miiii m

_

If

I

,

E

9

i

00 70

—I >

CERAMICS, GLASS, AND SOLID STATE SCIENCE DIVISION (565)

Hans P. R. Frederikse, Chief

Stanley Block, Deputy Chief

B. A. Hyde, Secretary

M. A. Clevinger, Secretary

J. Bartl ett, Secretary

E. R. Smith, Secretary

K. R. Morgan, Secretary

This Division is devoted to research that emphasizes several categories

of technologically important materials: ceramics, glass, and optical

materials. It employs a number of broad disciplines: crystallography,

solid state chemistry, and solid state physics. The nature of the work

is both applied and fundamental. The results of this work are new measurement techniques, reference data, and standard reference materials

as well as improved understanding of the structure and properties of

solids. The output is widely used in the ceramic, glass, and optical

industries both in processing, design, and lifetime assessment of devices,

components, and structures.

I The present activities of the Division are organized in four Tasks:

12151 STRUCTURAL CHEMISTRY FOR CERAMIC PROCESSING AND DURABILITY

12153 STRUCTURAL METHODS FOR PROCESSING, MANUFACTURING, AND

DURABILITY

12154 PROPERTIES, STRUCTURE AND STANDARDS FOR GLASS AND OPTICAL

MATERIALS

12155 DURABILITY OF CERAMICS AND GLASS IN SERVICE ENVIRONMENTS

Another way to explain the various aspects of the Division's work

is depicted in the diagram of figure 1. Basically the Division consists

of four groups with several overlapping and cooperative activities. The

collaboration extends to many other Divisions, research teams, and

individual scientists inside and outside NBS.

I The Division sees three major trends governing the direction of the

science and technology during the next few years, and consequently the

program is shaped accordingly. These three trends are:

1. Higher Temperatures and Pressures

An example of a technological development in this area is the

work of the Division on fluidic capillary pyrometers for the measurement

of temperatures (and oxygen partial pressures) in extreme environments.

This work is performed together with the Harry Diamond Laboratories

(U.S. Army) and the Trans Tech Corporation (Gaithersburg, MD), a cooperative

effort that has produced considerable interest from several large and

small industrial companies.

1

1

S'

i’l

363
Figure 1

.

CERAMICS, GLASS, AND SOLID STATE SCIENCE DIVISION

HIGH PRESSURE

Pressure Scale

Transformations

LI CRYSTAL STRUCTURE

Identification

Powders

High Intensity

Phase Equilibria^

Sensors

MHD

3 OPTICAL MATERIALS

DATA CENTERS

Phase Diagrams

Crystal Data

Materials for Fossil

Energy

| 2 CERAMICS 1

Refractive Index

Raman

NDE ^

THIN FILMS /

Optical Coatings

.Integr. Optics

(Stress) Corrosion

[4 GLASS PROPERTIES ~j

Vapor Pressure

Viscosity

Liquid Temperature

SRM

WASTE (Resource Recovery)

Recycled Glass

Flyash

NUCLEAR WASTE

364
Development of and research with the diamond anvil pressure

cell is one of the most important projects in the Division aimed both at

scientific and technological applications. NBS receives nearly daily

requests for information about the high pressure technique and research

results from researchers in the U.S. and abroad.

2. Small Dimensions

There is an ever-increasing interest in thin films, small

particles, and crystalline grains with dimensions of 1 nm to 1 pm. The

emphasis is on measurement techniques for the determination of composition

and properties of these small-dimension materials both for technical

applications (communication, optics, corrosion and protection, powder

processing, and manufacturing, etc.), and for scientific understanding

(differences and similarities of films or particles and bulk material).

A little more than a year ago the Division initiated a project

concerned with the production and characterization of glassy thin films.

This thin film facility, consisting of a deposition and a characterization

chamber has been in operation since early 1980. Glassy thin films to be

used as antireflection coatings for large glass lasers have been produced.

Other work is concerned with oxide layers formed on metals and with the

mechanism of cracking under stress.

3. Automation and Computerization of Data Acquisition, Storage

and Retrieval

Both the Crystal Data and Powder Diffraction projects have put

considerable emphasis on the automation of data acquisition through

minicomputer control and on the development of programs for data analysis,

evaluation, and dissemination.

Other activities that have benefited from equipment automation

and computerized data handling are the Raman project, Scanning Electron

Microscopy, the Fossil Energy Materials Data Center, the Thin Film Facility,

the High Pressure Research, the Phase Diagram for Ceramists Program, and

the acquisition of electrochemical materials data.

During this year the Division has been involved in the planning of

a number of programs for possible future implementation. In this context

we should mention the programs on Powder Processing for High Performance

Ceramics and on Glass Ceramics. Together with other Divisions of CMS,

plans were also developed in the areas of Mass and Charge Transport and

work on high pressure research on lubricants was suggested in the framework

of the Tribology program.

Other possible programs in the early planning stage including those

in the areas of Thin Films, Amorphous Materials, and Tribology.

365
The Optical Materials Projects of the Division received considerable

visibility through the organization of a Topical Conference on Basic

Optical Properties of Materials held at NBS, May 5-7, 1980.

The Division will benefit much from the training received by

Dr. R. S. Roth who spent three months at Arizona State University

familiarizing himself with the high resolution electron microscope and

performing some highly interesting research on lattice imaging of

several ceramic compounds.
STRUCTURAL CHEMISTRY FOR CERAMIC PROCESSING AND DURABILITY

Task 12151

The major goals of this task are:

to provide methods and obtain data for the construction and evaluation

of phase diagrams of systems containing oxides, sulfides, oxynitrides, etc.

Attention will be focused on silicates with additions of one to six other

oxides, which form the basis of the very important (coal) slags;

to study the composition, phases, and properties of various oxide

systems with either random or ordered defects or partly-ordered (modulated)

structures and to unravel the relation between the charge transport and

nonstoichiometry of these compounds; and

to assess the potential of ceramics and related materials for use in

energy conversion devices, for catalyzing chemical processes, and for

storing both beneficial and harmful elements and compounds.

As these goals are very broad it is necessary to be more specific in

the subtasks under investigation. The materials actually examined in the course of this study can be divided into two groups. The first group

consists of the seven most abundant oxides in the earth's crust which make

up the composition of coal slag and of most high volume refractory ceramic

materials (Na2 0, K2 0, CaO, MgO, FeO , A1 2 0 3 , Si0 2 ). The second group consists

of materials of interest in high technology ceramics, for electronics,

electrodes, catalysts, ionic conductors, dielectrics, etc.

The experimental determination of complex phase equilibria in a multicomponent system is a very laborious and time-consuming effort.

Therefore, we are seriously examining existing computer programs for

prediction of phase equilibria from thermochemical data. We hope eventually

to be able to modify such programs to be useful for the prediction of

solid-solid and solid-liquid equilibria in complex systems of interest

to the ceramic industry.

During the last several years and especially since July 1974, as a response to the national need, much of the work has been directed to the area of materials research for energy conversion. Most staff members in

the task are now working directly on materials problems in several energyrelated disciplines, for example ceramics for magnetohydrodynamic (MHD),

gas turbines, batteries, and fuel cells. At the request of DOE, members

of the task have begun several new projects, one on ceramics for high

temperature structural use in gas turbines, etc., such as Si 3 N 4 and SiC

based materials and another program on the possible use of ceramics as hosts for nuclear waste storage.

R. S. Roth spent three months at Arizona State University, collaborating

with the staff members of that facility's Center for Solid State Science on the use of high resolution electron microscope lattice images to elucidate

the nature of chemical reactions in specimens previously prepared at NBS, and

as a learning process to make it possible for 12151 task personnel to utilize

the new STEM facility now being set up in the Center for Materials Science.

367
Phase Diagrams for Ceramists

Subtask 1 of Task 12151

L. P. Cook, T. Negas, R. S. Roth (M. A. McKenna and J. T. Fitzgerald)

Within the last year it has become necessary, because of the size

of the final publication, to prepare as two volumes the 1980 supplement

to "Phase Diagrams for Ceramists." Numbering of these volumes will be

such that the 1964, 1969, and 1975 editions are treated as Volumes 1-3

and so these new supplements will be Volumes 4 and 5. It is anticipated

that they will be roughly the size of the previous volumes. Volume 4

will contain figures 5000-5590 (metal -oxygen , metal oxides, and oxygencontaining radicals). Due to the fact that many figure numbers actually

represent more than one diagram, Volume 4 will actually contain 748 phase

diagrams of oxide systems and 90 diagrams involving oxygen-containing

radicals or 838 diagrams in all. Volume 5 will contain figures 5591-6345

(molten salts, sulfides, oxycarbides, and oxynitrides, aqueous systems,

and ceramic/gas systems), with a total of 987 diagrams, as well as the

cumulative indexes, provided size limitations are not exceeded. The

American Ceramic Society has decided to publish this volume with in-house

computer assisted typesetting. Proofs of the diagrams and many of the

commentaries have already been received and Volume 4 is scheduled to

be published in late 1980. Volume 5 will probably be published in 1981.

The use of computer methods is continuing to increase in the preparation

of the compilation. Chemical arrangement of the book and preparation of

contents, chemical indexes, and author indexes is now done with a computer.

With the aid of a summer student and a computer scientist these procedures

as well as the editing procedures are being streamlined.

In addition, under a new program for central i zation of OSRD-sponsored

activities, the Phase Diagrams for Ceramists Data Center is collaborating

with the other NBS data centers in the development of common data formats

to allow the data centers to interact more efficiently and to allow the

development of generalized software for NBS data base management. It is

hoped in the future that all aspects of the compilation preparation will

make use of, insofar as possible, computerized file management. Although

the amount of time required initially for conversion to this type of

system is substantial, the outcome should allow more efficient use of the

limited number of personnel available for the Phase Diagrams for Ceramists

project.

An attempt is currently being made to evaluate published methods of

calculating phase equilibria diagrams and to find appropriate models to

obtain better fit between calculation and experimental data. Development

of the quasichemical silicate melt polymerization model begun last year

continued. The effect of varying oxygen partial pressure on the predicted

high temperature two liquid field in the system K2 0-Ca0-Mg0-Fe0

x -Al 2 0 3 -Si0 2 was examined by successive calculation of free energy mixing curves for

Fe

+3 /Fe

tot

of from 0.05 to 0.30. A rather dramatic effect was observed--

368
the predicted tendency for unmixing is almost negligible under reducing

conditions but becomes very great under oxidizing conditions. These

predictions will be tested experimentally.

Further development of the quasichemical model to the point where liquidus

surfaces can be reasonably well predicted for a range of multicomponent

melts is being attempted in the system K2 0-Ca0-Al 2 0 3 -Si0 2

. This is a system where a variety of melt structures might be expected, yet there are sufficient thermochemical data and phase equilibrium data such that a detailed analysis of melting curves can be carried out in order to

test polymerization theories. In practice this is done by comparison with

ideal solution curves. The greatest difficulty comes in explaining the

effect of A1 2 0 3 and it may be that the quasi chemical model will have to

be appreciably modified to accommodate alumina-rich compositions.

Ceramic Ion Conductors and Capacitors

Subtask 2 of Task 12151

}! R. S. Roth, H. S. Parker, T. Negas (L. C. Martel and M. C. Austin)

The following ongoing projects are being conducted in

col laboration with scientists of other organizations and other Divisions

at NBS, on the phase equilibria and crystal chemistry of ceramics of

interest for their ordered defect structures, "tunnels," layers, or threedimensional continuous defect arrays with possible applications for

oxygen, Li-, Na-transport , in batteries, etc.

Scheel ite-Related Phases —Several systems containing rare earths

and niobium or tantalum oxide were studied in previous years in an attempt

to elucidate the crystal chemistry of oxygen excess structures related to

CeTa0 4 and CeNb0 4

. During the course of the present year the phase

equilibrium diagrams of the systems LaNb0 4 -ThNb04 #

5

and LaNb0 4 -LaW0 4 >5 were completed (figure 1). Several manuscripts were prepared by R. J. Cava, now with Bell Telephone Laboratories, and members of this group.

A group of compositions from these two systems were carried to Arizona

State University for study by high resolution electron microscopy. In a collaborative study with Dr. A. Olsen of Arizona State University the

incommensurate nature of these materials was clearly demonstrated. A

material can be said to have an incommensurate structure when the diffraction

pattern cannot be explained on the basis of a small whole number superstructure

but instead has an irrational value to the multiple diffraction effects.

The electron diffraction patterns and their corresponding high resolution

lattice images demonstrated that these phases were incommensurate (figure 2).

A manuscript has been prepared by A. Olsen and R. S. Roth on the incommensurate

superstructures in these systems.

Neutron diffraction total profile analyses have been conducted on the

monoclinic CeNb0 4 , CeTa0 4 , and NdTa0 4 structures as well as the high

temperature orthorhombic LaTa0 4 phase. New mathematical treatments are currently being devised by A. Santoro of the Reactor Division in an attempt

to treat the structures of the incommensurate modulated phases of

369
Figure 1

1800

1600

1400 J .

"S'

I !

• • • • •

(b)

1200 .

1000

LaNbO,

20 40 60 80

LaWO,'4.5

Phase equilibria diagrams of the systems:

(a) LaNb0 4 -ThNb0 4>5 (b) LaNb0u-LaW0 4 e

5

.

370
Figure 2a. Bright field lattice image of La >9 Th ^bOi* 05

Figure 2b. Electron diffraction pattern of La P7 Th ^NbO u

371
Figure 2 c. Electron diffraction pattern of La.55Th.45NbO4.225-

372
CeTa0

4+x

and CeNb0

4+x

. These structures are currently being examined

on specimens supplied by NBS, using single crystal x-ray diffraction

techniques, by Dr. M. Marezio of the University of Grenoble, France.

Titanates--The phase equilibria and crystal chemistry of a portion

of the system Ba0-Nd2 0 3 -Ti0 2 is currently being studied in a collaborative

project with Dr. D. Kolar of Josef Stefan Institute, Ljubljana, Yugoslavia,

as part of a joint U. S. -Yugosl av agreement. Several compositions in

this system are being used in Yugoslavia in electronic components for

their property of high dielectric constant with low temperature coefficient

of the dielectric constant. Small single crystals of three new compounds

were prepared at NBS during the course of the phase equilibria study. A paper authored jointly by Yugoslav and NBS scientists has been submitted

for publication. It contains indexed powder patterns and unit cell

dimensions of the three phases, BaNd2 Ti 3 0 10 (1:1:3), BaNd2 Ti 5 0 14 (1:1:5),

and Nd4 Ti 9 0 24 (4:9).

Several compositions from this ternary system prepared at NBS were carried to Arizona State University for examination by electron diffraction

and high resolution lattice images. It was not too difficult for

Dr. A. Olsen of Arizona State to arrive at trial structures for the

1:1:5 and 1:1:3 compounds. A manuscript has been prepared by A. Olsen

and R. S. Roth on a crystal structure model of BaNd2 Ti 3 0 lo from high

resolution microscopy. Electron diffraction shows that the true unit

cell of this phase is monoclinic rather than orthorhombic. Calculated

lattice images correspond well with the observed images when using the

proposed structure based on neodymium titanate perovskite units three

octahedra wide separated by layers of Ba

+2 ions. The lattice image of

the 1:1:5 phase cannot be uniquely interpreted without high resolution

data which can be obtained on the new JEOL 200 CX instrument being

installed at Arizona State. Similar studies could probably be made

with the Phillips 400 microscope recently purchased by NBS, CMS.

Li 2 0-Containing Phases--In an ongoing collaborative study with

Dr. A. Santoro of the Reactor Division several phases are being examined

to determine the role of lithium in oxide structures, especially in those

of possible interest as lithium ion conductors. We have so far examined

and published results of studies of L i N

b

3 0 s and M-LiTa3 0 8 as well as Ta2 W0 8 (with all Li position vacant). The structure of H-LiTa3 0 8 has been

studied in collaboration with M. Marezio at Grenoble. The structure of the

ramsdellite form of lithium titanate with a composition about 1:3 to 6:17

L

i

2 0 : T i

0

2 has also been studied in collaboration with Dr. J. Mikkelsen of

Xerox Corp. using specimens prepared at NBS and at Xerox.

In an effort to obtain a better understanding of the nature of the

difficulty in locating Li + ions in oxide structures, several new series

of phases are being prepared for study by total profile neutron diffraction

powder analyses. The other compounds in the Li 2 0-Ta2 0 5 system are being

prepared as well as the phases in the systems Li 2 0-Zr0 2 and Li 2 0-Sn0 2 and nonstoichiometric solid solutions between them and the lithium

tantalates. Another phase under study is the nonstoichiometric lithiumlanthanum molybdate with scheelite structure.

atumtiaamm
A new collaborative study has begun with Drs. R. J. Cava and

D. Murphy of Bell Telephone Laboratories , Dr. A. Santoro of the Reactor

Division, and R. S. Roth of this Division. Dr. Cava is currently an official guest worker jointly with the Ceramics, Glass, and Solid State

Science Division and the Reactor Division. This study involves neutron

diffraction total profile analyses of Li -intercalated compounds. This

study differs from all the other compounds prepared for this program at

NBS by utilizing a unqiue room temperature preparative technique instead

of high temperature techniques. The resulting materials are thus non- equilibrium phases and are apparently greatly stressed, complicating the

structural analyses. The intercalated compounds currently under study

include Li 2 Re0 3 , LiRe0 3 , Li 2 V 2 0 5 , and LiV2 0 5

. The structures of the

rhenium compounds are essentially solved but the vanadium compounds are more difficult and the structure of V2 0 5 itself will be refined first to

obtain a greater insight into the problems.

Crystal Growth, Synthesis and Characterization

Subtask 3 of Task 12151

H. S. Parker, W. S. Brower, L. P. Cook, T. Negas (C. D. Olson)

The synthesis and crystal growth of phases in support of NBS materials

research programs and collaborative programs with other research laboratories on a national and international scale has continued. Where

necessary and appropriate, limited phase equilibrium studies were conducted

to aid in the delineation of stability fields and compositional limits.

In addition to supportive work for other programs in this task, crystals

of Agl have been grown by a solution technique for ionic conductivity

studies in collaboration with R. J. Cava of the Bell Telephone Laboratories.

Currently the same technique is being used in an attempt to grow crystals

of Cul for similar measurements.

A project on corrosive reactions in oxides has been terminated

during this year. The objectives of this study, conducted by H. S. Parker

and C. D. Olson, with NASA support, were to examine the nature and

extent of sample-container reaction up to and including liquidus temperatures and to provide phase equilibria data of interest in the study of

slag-electrode reactions in MHD systems. A further objective was to

consider alternate techniques for containerless processing.

The initial work on the KFe0 2 -Fe 2 0 3 portion of the study was extended

to include selected compositions in the K2 0-Fe0-Fe2 0 3 -Si0 2 system,

studied at controlled partial pressures of oxygen. In contrast to the

earlier work with compositions containing Fe 2 0 3 where chemical corrosion

of platinum was found to be minimal at temperatures as high as 1600 °C, severe reaction with platinum was found as the amount of Fe

+2

in the

specimens increased. The volatility of potassium in this system remains

a problem during heating at high temperatures.

The possibility of electromagnetic positioning of selected ceramic

oxides having good electrical conductivity at low temperatures (100 0 to

300 °C) during low gravity experiments in space was explored with NASA

and other NASA contractors. The collaborative effort with NASA Marshall

374
Space Flight Center indicated that although suitable for low gravity

experiments in space, acoustic levitation and positioning could not be

achieved at useful temperatures in a one-gravity environment.

The scanning electron microscope remains an essential piece of

equipment for phase equil ibrium-related activities. Examples from the

past year include: detection and compositional determination of invariant

melts in the system K2 0-Ca0-Al 2 0 3 -Si0 2 for comparison with theory; the

study of interfacial ly controlled phenomena in the system K2 C0 3 -KA10 2 , including the detection of possible mesomorphic behavior and the imaging

of what may be long-period crystalline structures; the study of K2 C0 3 , K2 S0 4 /steel interaction in MHD downstream corrosion simulation experiments;

the study of S

i

3 N 4 sintering and reaction.

In cooperation with the surface microanalysis group at NBS, currently

available software for data reduction on energy dispersive x-ray spectra

is being adapted to the system. This will allow spectrum stripping and

peak deconvolution for easier identification of spectral features and

quantitative analysis, including the light element data collected with

the windowless system.

Materials for Fluidic Capillary Pyrometer Temperature Sensors

Subtask 4 of Task 12151

T. Negas , H. S. Parker, W. S. Brower (L. P. Domingues)

This subtask in collaboration with Harry Diamond Laboratory (HDL),

has been concerned, with developing new techniques of measuring temperature

and oxygen partial pressure simultaneously in extreme environments under

actual industrial use conditions. In principle, a fluidic capillary

pyrometer (FCP) is analogous to an electronic resistance thermometer.

The fluid resistance of a capillary is directly proportional to viscosity

which, in turn, is a function of temperature. Laminar fluidic pressure

amplifiers are utilized to amplify small pressure signals to usable

outputs which may be detected by a pressure gauge or transducer. Having

constructed some "first-generation" fluidic temperature measurement

circuitry, HDL researchers turned their attention to the actual contact

temperature sensor or capillary probe. It soon became clear to this

group that they needed expert advice with respect to the materials

problems related to the high temperature development of such a sensor.

In July 1979 the HDL group contacted T. Negas at NBS and discussed with

him the various requirements and possible solutions. This association

developed into close collaboration when a hybrid fluidic temperatureoxygen concentration sensor was developed jointly by NBS and HDL groups

(A Hybrid Fluidic Temperature-Oxygen Sensor , Fall Meeting Electronics

Division, American Ceramic Society, Williamsburg, Virginia, October

1979). Subsequently, funding from and cooperation with HDL researchers

has increased progressi vely

.

Initially, the HDL group requested ceramic oxide-based sensors of

specific design: a double-bore rod (0.25 in. dia. each bore) with a capillary 1-1.5 in. length, 0.030 in. dia.) connecting the two channels

at one closed end. In cooperation with Trans Tech., a small specialty

375

MOM) iiiiHuiii imimfinm
ceramics company (represented by L. P. Domingues, now an official guest

worker with the Ceramics, Glass, and Solid State Science Division),

research culminated in the production of these sensors constructed from

alumina, zi rconia:

Y

2 0 3 , and spinel (MgAl 2 0 4

). The zi rconia-based

sensors are transformation toughened materials. Probes up to 24" in

length were provided. Several of these sensors were installed in U.S.

Army forging furnaces at Scranton, Pennsylvania. These continue to

function (~ 6 months) and are destined to be interfaced with existing

furnace controls.

More recently, work at NBS has expanded to (a) develop new designs

for FCP sensors, (b) develop and/or select construction materials for FCP sensors for specific applicatons, (c) fabricate FCP sensors in cooperation

with private industry, (d) provide calibration (not certified) of sensors

in the 1000° to 2400 °C range, and (e) test durability of sensors within

environments simulating specific applications.

Ceramic, oxide-based sensors having unique, monolithic construction

were designed and fabricated. Alumina sensors (24" length) were fabricated

to include four internal bores (0.25" dia.), one pair being linked by a capillary while the other pair terminates within the region of the

capillary at the closed, sensing portion of the probe. Other improvements

in sensor design are under investigation to enhance response time and to

simplify processing.

Oxide coated metals and carbides are obvious candidate materials for

FCP sensors for certain applications. Their high thermal conductivity

ensures rapid response of the probe and contributes to high resistance

to thermal stress. As this task has focused on materials for applications

well above 1200 °C in various environments, only the refractory metals

(e.g., Mo, W, Ta, Zr) and graphite have been considered.

Graphite sensors were designed and fabricated from commercial, high

purity, and high density materials. A unique design was established at

NBS and successfully tested to 2400 °C. Rather than using a capillary,

a porous, permeable graphite plug was used as the fluid resistor within

the sensor. Argon was used as the working fluid.

Ceramic coated molybdenum sensors also were constructed to operate

within oxidizing or reducing environments. Emphasis was placed on long

duration (~ 6-8 hrs) temperature measurements within molten iron and/or

steel in the presence of RF and/or high electric fields. Molybdenum sensors were protected against oxidation by several coatings using combinations of

cermets and oxides. In cooperation with another private company, APS

Materials, these coatings were applied by arc plasma spray (APS) methods.

Preliminary testing at NBS and at the General Motors Research Labs,

Warren, Michigan, demonstrated that the coated Mo-sensors will survive

the thermal shock associated with rapid immersion into molten iron at

1200 and at 1500 °C. One probe operated nearly six hours in molten iron

with cycling between 1200 to 1500 °C (note that conventional practice is

to use disposable thermocouples, ^ 15 s lifetime). Failure of the

protective oxide-based coatings on Mo, in all cases, is at the molten

376
iron-air-slag interface especially at temperatures above ^ 1400 °C.

Recent experiments (1500 °C, 7 hrs) indicate that corrosion at this

interface can be controlled by sacrificial materials (e.g. , castables)

around the sensor to extend the lifetime of the oxide-based coatings.

Four-bore alumina FCP temperature sensors were installed within a periodic kiln at a private ceramic firm for the purpose of measuring

firing temperatures up to ^ 1600 °C in air. The fluidic measurement

circuitry (not the FCP sensor) became unstable due to rapid ambient room temperature fluctuations resulting from large cooling fans. NBS determined

that the cause could be attributed to pressure fluctuations which propagate

through the system at sound velocity and HDL improved the circuitry and

insulated the copper tubing which transports air to and from the sensor

to solve the problem.

During this year, HDL and NBS demonstrated that temperature can be

measured accurately by fluidics technology combined with appropriate

materials and design for a FCP sensor. This technology is competitive

with other temperature measurement methods when costs are compared. For

example, the protective sheath for a Pt/Rh- and/or W/Re-based thermocouple

can obtain the same measurement without the expensive wire. In some applications, the FCP sensor may be the only means by which an accurate

contact temperature measurement can be performed. The following

laboratories have expressed active interest in utilizing some form of the

new sensors: Dupont, General Motors, Kaiser Corp. , Electro-nite, Inc.,

Union Carbide, APS Materials, Argonne National Laboratory, Oak Ridge

National Laboratory, U.S. Steel, Acurex Corp., Sandia Labs., Kennecott Corp.

In cooperation with three private firms, highly efficient sprayable

powders of al umi na-chromi a solid solutions are also under development.

Coatings of chrome oxide (Cr 2 0 3 ) and aluminum oxide (A1 2 0 3 ) by arc plasma

spray (APS) are used extensively in the chemical processing and textile

industries due to their hardness and resistance to corrosion. Available

alumina powders deposit on substrates as metastable (y, 6, etc.) forms.

Utilization of Cr2 0 3 coatings for resistance to corrosion above ~ 700 to

800 °C results in extensive fissuring due to undetermined factors. Pure

alumina coatings fail because of volume changes associated with transition

of metastable forms to a-alumina above 1400 °C. Alumina powders, containing

ten and twenty weight percent chromia in solid solutions, were processed

and efficiently (>> 80 percent) sprayed by APS. For both compositions, a nearly equal mixture of metastable aluminas and a-alumina solid solution

products were deposited. To our knowledge this is the first time that

a-alumina has been deposited by APS. Coatings are dense (> 90 percent of

theoretical) and do not fissure or spall up to 1200 °C on rolled steel.

In contrast, pure alumina coatings delaminate under similar conditions.

Future work will include testing of these coatings above 1200 °C using

Mo-metal substrates.

377
Nuclear Waste Management

Subtask 5 of Task 12151

T. Negas, R. S. Roth

This project is part of a recently initiated DOE program on waste

forms of ceramics and glass. It will include waste forms, measurement

techniques, "standard materials," and leaching studies. During 1979-1980,

the following visits and conferences were attended by T. Negas to obtain

technical insights for the NBS program proposed to DOE: (1) Oak Ridge

National Laboratory; (2) Savannah River Laboratories; (3) Idaho Falls

National Laboratory; (4) Nuclear Regulatory Commission review of the

Department of Energy nuclear waste management program (February 1980),

and (5) "Scientific Basis for Nuclear Waste Management," Materials

Research Society, Boston, Massachusetts, November 1979.

Additionally, numerous internal technical and administrative

meetings were attended to help formulate the NBS policy and program

for nuclear waste management through DOE. A significant part of Chapter II,

Technical Issues (Nuclear Waste Management document from NBS to DOE), was written. Several meetings were attended as an observer to NBS-EPA

negotiations regarding research for problems related to infiltration of

radon in the environment.

378
STRUCTURAL METHODS FOR PROCESSING, MANUFACTURING, AND DURABILITY

Task 12153

The program of the Crystal lography Group is applied both to this

task and to Task 12155, Durability of Ceramics and Glass in Service

Environments. The latter portion of the program is reported in Task

12155. The objectives of the program are to: provide x-ray and thermal

expansion SRM materials; compile and disseminate Crystal Data ; prepare

and publish standard x-ray patterns with JCPDS--Internati onal Centre for

Diffraction Data ; develop a new high pressure x-ray method for radial

distribution of liquids and amorphous materials, correlate with and

extend range of our viscosity measurements; determine the PT behavior of

semiconductors by optical, x-ray and/or electrical measurements; determine structures of compounds of interest to industry and government

(FDA); develop measurement methods for selected area diffraction and

compound analysis; and improve measurement methods by x-ray diffraction

of spacings and intensities using automation and computer analysis.

New programs initiated this past year include the characterization

of fly ash from various fuels and power plants for the Office of Recycled

Materials and DOE, nuclear solid wastes for DOE, determination of the

partial structure factor of glassy metals as a function of pressure for

DOD and, in cooperation with NRL, the design and construction of a crystallographic line for the synchrotron source at Brookhaven. The relationship

with the JCPDS — International Centre for Diffraction Data has been

strengthened by hiring a senior scientist for the associateship. Information

for ongoing and new programs such as the preparation, characterization,

and certification of silicon dioxide polymorph SRM for NIOSH is presented

below.

Crystal Structure Analysis and Materials Characterization

Subtask 1 of Task 12153

A. D. Mighell, C. R. Hubbard, J. K. Stalick, V. L. Himes

The combination of single crystal and powder diffraction methods

with the Crystal Data and Powder Data Files and with recent developments

in lattice theory (collaboration with A. Santoro) represents a unique

capability for structure work and materials characterization. Consequently,

many collaborative projects with other groups at NBS and with university

and industrial scientists have taken place during the year. One student,

R. M. Doherty, who has carried out three structure determinations with us,

will receive her Ph.D. from the University of Maryland in August 1980;

a second student, M. J. Lynch, who has completed one structure with us will

complete his thesis (University of Maryland) in the fall; and a third

student, V. L. Himes, an NBS-Catholic University COOP student, who has

completed structures and theoretical work with us, is well along toward

completion of her work toward her Ph.D. degree. Several structures in

collaboration with the FDA (S. M. Page and W. H. DeCamp, guest workers from

FDA) have been carried out and a structure with Allen Siedle of the 3M

Company has been determined.

379
To improve our facility we are: (a) adding an up-graded module to

the Syntex diffractometer which will allow more control over data collection, (b) linking the Crystal Data File to the Syntex diffractometer

for characterization, and (c) implementing improved methods to characterize

lattices. Specifically, J. K. Stalick has devised an elegant procedure

that will allow one to interactively reduce cells and calculate powder

patterns for a rapid characterization and evaluation of materials;

V. L. Himes has worked out and applied a method for symmetry determination

that has a number of advantages over existing procedures (see below);

and C. R. Hubbard and J. K. Stalick have greatly augmented the AIDS program

which is especially useful in materials characteri zation.

During the year, a number of structures have been solved and materials characterized. Below we give examples of structure work carried

out: (a) the structure of a corrosion inhibitor, (b) the structure of an electron-donor-acceptor complex, and (c) typical FDA structures. Also we give a brief summary of work carried out on lattice theory and the

application of lattice theory to materials characterization.

Lattice Theory : (Collaborative work with A. Santoro) During the

year considerable work has been carried out in the areas of 1 attice/formul

a

registration and symmetry determination. This work has many applications

with respect to materials characterization and to the understanding of

materials properties that are lattice dependent.

Regi strati on : Data files containing diffraction information on solid state materials are rapidly expanding. Consequently, it has become

necessary to develop computer techniques to register materials entering

large data bases of solid state materials. Registration based on lattice

parameters and empirical formulae is especially effective. In our present registration procedure, the lattice is uniquely represented by

the reduced cell and the elements in the formula are uniquely specified

by prime numbers. Such a method has been applied for several years to

register new materials entering the Cambridge Crystallographic Data File

and is currently being adapted to register materials entering the NBS

Crystal Data File. The Cambridge File contains data on over 25,000

carbon containing compounds. For these materials, we have found that

lattice/formula registration is extremely effective. In fact, our experience shows that it would be highly desirable if organic materials

were routinely characterized by cell parameters in addition to traditional chemical analyses. A solid-state registry number which would

allow one to identify the same compound in different data bases could

also be based on lattice/formula and allow one to distinguish polymorphs.

Registration procedures will be greatly expanded by matrix techniques

(Santoro, Mighell, and Rodgers, Acta Cryst. , in press) which will allow one

to establish many types of lattice relationships. For example, by using

these techniques, derivative lattice relationships can be immediately

established. The registration program, with minor modifications, can be

converted into an identification program that can be used in conjunction

with the Crystal Data File for materials characterization and identification. A general program is being written in RATFOR (rational FORTRAN)

by John Rodgers (of the Unversity of Adelaide) that is designed to be

transportabl e (i.e., machine independent).

380
Symmetry : In a paper published this year (Acta Cryst. A36, 321) it was shown, based on an analysis of the data in the Crystal Data File,

that there is a close correlation of metric (size and shape of the unit

cell) with crystal symmetry. Clearly, in the experimental determination

of crystal symmetry, one should first determine the metric symmetry.

For example, one can quickly prove that a crystal is tri clinic from the

metric symmetry alone. In the analysis of the cells with our crystal

data evaluation program (AIDS), symmetry is determined via reduction

techniques. Although reduction procedures are perhaps the most reliable

for symmetry determination, there are several non-trivial problems with

this method when used automatically without any human interaction.

First, experimental errors cause problems in treating the inequalities

inherent in the special conditions for reduction. In some cases, it is

difficult to establish a single "correct" reduced cell for the lattice.

Second, in using reduction procedures, one must transform an experimentally

determined cell to the reduced cell. Third, it is difficult to establish

pseudo-symmetries. Consequently an alternative method to determine

symmetry is being developed.

In a recent paper (Santoro, Mighell, and Rodgers, Acta Cryst., in

press), it has been shown that the lattice relationships can best be

understood by determining matrices that relate cells in the same or different lattices. An algorithm (B-matrix) to determine such matrices

was presented. As part of her thesis work, V. L. Himes has developed a routine analytical technique (based on a modified B-matrix algorithm) to

determine lattice symmetry. In using this technique, one finds all the

transformation matrices with integral coefficients (range 0-20) that

relate the cell to itself. One then determines the symmetry from the

set of matrices obtained. The method is superior to reduction in a number of ways. With this technique, one can simply determine the

lattice symmetry from whatever cell has been determined without transformation of the cell to a standard or reduced cell. The most important

features of this method are that one can determine the highest possible

metric symmetry within whatever tolerance one specifies, that pseudosymmetries are immediately transparent, and that the method is inherently

simpler and safer than reduction as one does not need to worry about the

inequalities inherent in reduction theory. The technique has been

successfully applied to a series of experimental problems in our laboratory.

Corrosion inhibitor for copper : (V. L. Himes, thesis work) Benzotriazole (BTA) is a widely used corrosion inhibitor for copper. To help

elucidate the nature of the protective film formed by benzotri azol e on copper, we have solved the structure of a coordination complex between

the anion BTA and copper. The structure solution revealed a new and

novel bonding mode for BTA in which three contiguous nitrogen atoms in

the same ligand are coordinated to three different copper atoms.

The complex (C 56 H 60 Cu 5 N 22 ) crystallizes in the tetragonal crystal

system, space group P42 x c, unit cell parameters a = 1 3^836(4) A and c = 16.686(4) A, Z = 2, d , = 1.41 and d , = 1.413 g cm 3

. There are two

obs calc a neutral complex molecules in the unit cell, one at the origin and one at

381
the center of the cell. A view of the complex down the c-axis is shown

in figure 1 (for clarity only three nitrogen atoms of the two benzotriazole

ligands coordinated along the c-axis are shown and the entire molecule

at the orgin has been omitted). The large neutral complex has 4 symmetry

with a central Cu+2 atom in octahedral coordination to six BTA ligands.

These same ligands bridge the central Cu+2 ion to four Cu+1 ions each of

which is tetrahedral ly coordinated to three BTA ligands and one t-butyl

Figure 1. Copper Benzotriazole Complex (C 56 H 60 Cu 5 N22 )

382
El ectron-donor-acceptor (EDA complex) (R. M. Doherty thesis work) A

molecular complex between two molecules may be defined as an association

of definite stoichiometry that is stronger than a van der Waals attraction.

Complexes involving pyrene fall into the class of molecular complexes

known as electron-donor-acceptor (EDA) complexes. Such complexes involve

an association between a donor molecule of low-ionziation potential and

an acceptor molecule of high electron affinity. In the compound in this

study, the donor is pyrene and the acceptor is a substituted cyclopentenedione.

The crystal structure analysis was carried out to determine the

molecular parameters of this complex. The complex crystallizes in the

trie! ini c space group PI with* two donor and two acceptor molecules in

the unit cell. The two acceptor molecules are centrosymmetrical ly

related to one another. However, each pyrene lies on a center of

symmetry, so that the two pyrenes are crystal! ographically independent

of one another. The packing consists of stacks of alternating donor and

acceptor molecules (figure 2a) along the body diagonal of the reduced

cell (in a similar potential charge transfer complex) (V. L. Himes, thesis

work), the stacks were found to be along the shortest unit cell dimensions

(figure 2b). The least-squares planes of the molecules are not quite

parallel to one another. Such non-parallelism of the molecules in

other EDA complexes has been cited as evidence of specific localized

interactions, presumably of the charge transfer type, between donor and

acceptor.

Figure 2a Figure 2b

FDA Structure Work : The FDA structure program has been stabilized

with respect to funding and materials to be studied. Samples are being

prepared by several groups at FDA. In this work special emphasis is

383
placed on: (a) the correlation of drug stereochemistry with its biological activity, (b) polymorphism in drugs, and (c) molecular structure of

toxi ns.

From stereochemical data, one can establish the basis for rationally

designed drugs for the treatment of such diseases as cancer. This year

a paper was published on 4-phenyl cyclophosphamide, a compound that is

closely related to cyclophosphamide (CP) which is a well known drug for

the treatment of a broad spectrum of human cancers, (figure 3)

Figure 3. 4-phenyl cyclophosphamide

From data on polymorphism, one can establish correct dosages of

drugs. It is essential that drug preparation and crystallization

procedures be carefully monitored to assure that one obtains the desired

polymorphic form. During the year we have solved the structure of one polymorph of Carbamazepi ne , an important commercial drug, and we are starting to work on a second form. We plan to relate the two forms and

to study the conditions under which they form.

Figure 4. Carbamazepi ne

384
From data on molecular shape, one can attempt to understand the

mechanism of a toxin. The structure of xanthomegnin (C 3O H 2 20i2)> a toxic metabolite of a pathogenic fungi, was solved and found to be

significantly different from what the chemist thought. The molecule

crystallizes in a tetragonal space group and is shown in figure 5.

Figure 5. Xanthomegnin

385
Crystal Data

Subtask 2 of Task 12153

A. D. Mighell, J. K. Stalick, R. J. Boreni

The recent emphasis of the Crystal Data project has been on the

conversion and expansion of all phases of the data operation (input,

evaluation, and dissemination) to computer-based procedures. A major

effort has been made to establish the best format for a master data file

that will serve the internal operations of the project as well as the

needs of the scientific community. This effort has been aided by the

completion of the analysis of a questionnaire sent to users of Crystal

Data products. To date over 3500 volumes of Crystal Data have been

sold.

Automation of NBS Data Centers : A principal objective of the Office

of Standard Reference Data (OSRD) is to increase the automation of the

various data center operations. The increasing size of the data bases

requires computerization for efficient editing, evaluation, and dissemination of the data. The Crystal Data project was selected as a prototype for complete conversion to a computer-based operation, particularly

with respect to the creation of a master data file that can be used for

on-line searches, product generation, and research analyses. The project is to develop convenient methods to build a master data file and

assist the durability data centers, as well as other OSRD data centers,

in file design and manipulation. Cooperation in the design of file

formats is essential; it permits compatible on-line dissemination of the

various data bases, allows for a common assignment of chemical registry

numbers, permits the writing of efficient typesetting software, and

greatly simplifies software problems in that common editing and data

base management routines can be used.

Construction of the Master Data File : The input procedures,

content, and format of the master data file have been completed during

the year in collaboration with C. R. Hubbard of NBS and with the Cambridge

Crystallographic Data Centre, the Joint Committee on Powder Diffraction

Studies (JCPDS)--International Centre for Diffraction Data, and the Metals

Data Center (Ottawa). The NBS Crystal Data File and the JCPDS Powder

Diffraction File have been designed with a common format to permit common

input and data manipulation procedures, joint data evaluation routines,

and common data dissemination and publication techniques. Moreover, common evaluation of single crystal data and powder data enhances the

quality of both data bases.

(1) Format : The content and format specifications for the master

data file have been completed, and preliminary documentation

has been written.

(2) Data Input : Computer programs have been written to allow for

data input via computer terminals. A computer "form" is used

to input data base entries and record them on magnetic tape

cartridges, and a preprocessor program (C. R. Hubbard) has been

386
written to convert the data to the proper format. A program

has also been written for interactive on-line data input for

research analysis runs.

(3) Evaluation and Data Base Building : The computer programs AIDS

has been extensively rewritten in collaboration with C. R. Hubbard.

The program evaluates the data, checks for consistency, transforms the data to standard settings, and builds a data base

entry. Evaluation routines include transformation of the

original unit cell to the Crystal Data cell and the reduced

cell, assignment of a quality index to cell parameters,

transformation of space group and assignment of space group

number, and flagging of unusual values. The chemical formula

is analyzed for legal element symbols, and an empirical

formula, molecular weight, and density are calculated; the

calculated density is then compared with the authors' measured

and calculated densities. Journal references are checked for

legal CODEN 1 s, and journal abbreviations are printed. The

reduced form and reduced form number are determined, and the

metric symmetry is compared with the reported crystal symmetry.

Powder pattern analysis includes calculation of d-spacings,

indexing of lines, comparison of observed and calculated

powder lines, and calculation of figures of merit.

Data Registration and Identification Procedures : Registration

procedures are used to find out if the same entry, or a related entry,

is already in the data base so that evaluation can be carried out with

respect to the set of known data. The registration software based on the crystal lattice and chemical formula is being written in collaboration with J. M. Rodgers, University of Adelaide, and the procedure will be

publ i shed.

Crystal Data Identification File : A high priority has been set on the preparation of a distribution file with four lines per entry for the

rapid identification and characterization of unknown materials. The

file is being prepared in collaboration with the Cambridge data center

and OSRD with a target completion date of late 1980. It contains the

reduced cell, space group and space group number, cell volume, density,

chemical name and formula, literature reference, and reference to Crystal

Data Determinative Tables for approximately 60,000 substances. The

Chemical Abstracts registry number will also be appended to the file.

The names and formulas of inorganic substances have been extensively

revised so that the nomenclature follows consistent rules, thus permitting

computer searching and typesetting. A simplified version of the file

has been used during the year to identify substances for the FDA and the

JCPDS, and the procedure has been quite successful.

The initial mode of file dissemination

Chemical Information System (CIS). The CIS

is now working on a limited test version of

modes of dissemination are being explored,

be distributed to national data centers for

will be on-line through the

interactive search software

the file. Other potential

The identification file can

use within the country; one

387
such center in Germany has already requested lease of the file, and it

is likely that other data centers affiliated with the Cambridge data

center will also be interested in leasing the file. One manufacturer of

automated di ffractometers is considering incorporating the file, with

appropriate search software, into their instrument so that a cell can be

determined and the substance identified automatically. The file could

also be made available on tape for private use, and publication of a printed version is also under consideration.

The use of the file for identification of substances was presented

at a special session on crystallographic data bases at the American

Chemical Society meeting in Washington, D.C., in the fall of 1979. Other

types of research applications are possible. For example, a systematic

density analysis was carried out on similar data in the Cambridge file

by a scientist at Lawrence Livermore Laboratory. Also, we have found

through analysis of the file that the crystal symmetry can almost always

be deduced from the unit cell parameters alone; a paper on this subject

entitled "Lattice Symmetry Determination" was well received, and should

lead to rapid and more accurate symmetry determinations on a routine

basis.

Research Applications of AIDS : The evaluation routines in the

computer program AIDS should also be of value to the general scientific

community. Evaluation of data prior to publication will lead to better

data in the literature. We are preparing a version of AIDS for public

release. The programming is near completion, and a preliminary documentation has been prepared. Standard ASCII FORTRAN has been used to

permit use on a wide variety of computers, and the program has been

modified to accept input from computer terminals or punched cards. The

availability of the program and its research applications was presented

in August of 1980 at the American Crystallographic Association meeting

in Calgary and at the Denver X-ray Conference.

Computer Manipulation of Data : During the year considerable com- puter time has been made available from the Director to the Crystal Data

project. This has allowed us to change our mode of operation from a batch to an on-line mode, and the on-line editing has proved to be much

more practical and efficient than batch methods. The additional com- puter time, moreover, has allowed us to develop and to test procedures

for the management of large data files. The handling of large files on the UNIVAC has proved to be much easier than expected and clearly

demonstrates that a large computer with adequate software is to be

preferred for large data files.

Analysis of Questionnaire Response : The analysis of the response

to the questionnaire on Crystal Data was completed and published as NBS

Technical Note 1112. The results indicate a high frequency of use of

Crystal Data , with particular application to materials analysis and

design. The survey suggests a need for the development of a rapid and

inexpensive method of unit-cell determination as well as education of

the scientific community in the use of the single-crystal method for

identification of unknown materials. More complete coverage and con388
soli dati on of entries are also suggested. The necessity for computerbased methods of data base dissemination is indicated, with particular

importance for research applications.

Powder Diffraction

Subtask 3 of Task 12153

C. R. Hubbard, S. J. Carmel

Automation : Two powder diffractometers are now operating under

control of the Interdata 7/16 minicomputer. The control program AUTO,

written by R. L. Snyder (Alfred University), C. R. Hubbard and

N. C. Panagiotopoulos (JCPDS), is an interrupt-driven executive which

permits execution of various sub-algorithms (pattern collection, data

collections, quantitative analysis, file transfers, counting, stepping,

termination, etc). For quantitative analysis the time spent counting

the background and peak regions can be optimized within the constraint

of a preselected total time or preselected statistical error. The

actual data collection parameters are prestored on a run file produced

either on the mini or the Uni vac 1108. The output data file contains a complete definition of the instrument, the run paramaters, and the

experimental data. Because of limitations of memory and operating

system all data will be transferred to the Univac 1108 for analysis.

Currently this is achieved by means of floppy disks. In the near future

it should be possible to access the NBS net and transfer any ASCII file

between the mini and the U 1 1 08 at 9600 baud.

Computer Analysis of Powder Patterns : A digitally recorded powder

pattern is processed on the Univac 1108 using a set of programs developed

at Alfred University by Dr. C. Mallory and Professor R. L. Snyder. These

programs use second derivative peak finding algorithms and allow a 2 stripping, data smoothing, and background subtraction. A coordinated

set of graphic programs has also been implemented to produce plots on a Tektronics 4012 terminal (purchased by the JCPDS) for examination by the

experimentor. This capability has been found to be essential as it

maintains input from the di ff racti oni st in the interpretation of the

digital data. Analysis of overlapping profiles will be added to the

analysis capability early in FY81 . Profile analysis will significantly

improve the quality of d-spacing and intensity measurements of over- lapping lines. Extensive enhancement of the plotting capability is also

planned. This includes the potential to direct the plots to other

plotting devices and to permit user interaction at the Tektronix terminal.

A program for 29 calibration using an internal standard, such as SRM 640

Si powder, has been written. The program allows for precorrecti on for

known systematic errors and then fits a polynomial through the correction

based on the internal standard lines. The lines of the unknown are then

corrected and the corrected 20's and ct(29)‘s are output. The program

will be expanded to allow for external calibration and for choosing the

order of the polynomial based on a goodness-of-f i t criteria.

Quantitative Analysis : A program P0WDER*QUANT which can be used

for three methods of quantitative analysis by x-ray powder diffraction

has been written by Professor R. L. Snyder (Alfred University) and

389
C. R. Hubbard. The program allows for analysis by the internal standard

method (see SRM's below), the known chemical composition method and the

spiking method. The automation system discussed above is programmed to

intelligently collect the appropriate data for each method.

The algorithm allows for overlapping lines as well as imposition of

flexible external constraints such as I x. = 1 and/or chemical analysis.

The program uses the L. E. Copeland and R. H. Bragg procedure for over- lapping lines as generalized by C. R. Hubbard to incorporate the Refer- ence Intensity Ratio (I/Ic) and relative intensities. The program

PQWDER*QUANT can also be used to determine relative intensities and

the Reference Intensity Ratio. X-ray powder diffraction analysis is

being extended in an attempt to analyze for the percent amorphous phase

in a sample. The procedure involves integrating the area under the

amorphous hump in the diffraction intensity. Both the internal standard

and the spiking analysis methods will be tested to determine sensitivity.

If successful this technique will be used in analysis of glass content

in fly ash samples and the percent crystallinity in quartz, cristobalite

and tridymite candidate SRM samples.

Standard Reference Materials : The certification of a-Al 2 0 3 , Ti

0

2 Rutile, ZnO, Cr2 0 3 , and Ce0 2 for powder diffraction intensity standards

has been completed. The cell parameters, the relative intensities, and

the Reference Intensity Ratios (RIR) are given in order that the materials

may be used as an internal standard in quantitative analysis by x-ray

powder diffraction. Procedures and pitfalls of calculating and

measuring the Reference Intensity Ratio were previously reported. This

information coupled with these SRM's simplify the task of performing a quantitative analysis. The resultant accuracy is limited by sample

preparation (a serious problem) and the standards. The accuracy of the

re 1 RIR and I values are between ± 2 percent and ± 5 percent depending on the

phase. The relative intensities for each phase were measured for samples

prepared in a variety of methods including side drifting, spray drying,

and coating with krylon. Both stationary and rotating samples were

employed. The calculated and average relative intensities generally

agree within ±1 or ± 2 on the relative intensity scale (I = 100)

except for a-Al 2 0 3 where the differences have been ascri bec3 a £o the use

of a spherical approximation for the electron density about the atoms.

The Reference Intensity Ratios were determined from measurements on all

possible binary mixtures, each prepared at two or three different weight

fraction ratios. The internal consistency and the agreement with calculated

values was better than 5 percent.

Candidate materials for a large d-spacing SRM have been selected

(wet ground muscovite mica and f 1 uorophl ogopi te synthetic mica). Each

of these materials exhibit 00£ preferred orientation when pressed which

reduces interference with sample lines. Another candidate, thallous

hydrogen phthalate, can be used to calibrate sample lines below 30° 20

but not above 30° due to its increasingly complex pattern. Bulk samples

will be ordered by September 30th and certification completed early

in FY81.

390
Future SRM projects include certification of quartz, cristobal ite , and tridymite powders for percent crystallinity, lattice parameters,

relative intensities, and Reference Intensity Ratio. This project will

be performed in collaboration with Dr. R. L. McKenzie (553-Gas and Particulate Science) with support from NIOSH and OSRM. The OSRM is also

supporting development of a crystallite size standard in collaboration

with Dr. A. L. Dragoo (561-Chemical Stability and Corrosion). The proposed

phase is MgO which can be crystallized in the 100 to 2000 range by

precipitation-decomposition methods as well as by condensing a smoke

onto a cold surface. The latter method may yield individual crystallites

whose dimensions can be measured by electron microscopy. Such measurements will be valuable as a primary reference method for checking and/or

calibrating the Fourier line broadening analysis.

Standard Patterns : Six associates of the JCPDS--International

Centre for Diffraction Data (M. C. Morris, Director; H. F. McMurdie,

Consultant; E. H. Evans, B. Paretzkin; N. Panagiotopoul os ; and C. Wingo)

along with S. J. Carmel and C. R. Hubbard continue to produce high

quality x-ray diffraction patterns as well as evaluate and edit data

from the literature. Section 17 of NBS Monograph 25 will be published

in September 1980. This is the 26th of the series of "Standard X-ray

Diffraction Patterns". Section 17 will include approximately 60 experimental patterns as well as a review of methods used at NBS for

obtaining the patterns.

Each year the JCPDS publishes a supplement to the powder data file

(PDF). The complete file, recognized as the standard reference source

for powder diffraction analysis, consists of 29 sets of data for nearly

33,000 crystalline phases. Due to the continuous growth of the PDF, a major effort of the JCPDS is to produce subfiles for selected fields.

Subfiles currently available are: (1) Frequently Encountered Phases

(FEP)/Common Phases (CP), (2) Minerals, (3) Metals and Alloys, and (4)

NBS Patterns. M. C. Morris, Chairperson of the FEP/CP subcommittee con- tinues to review and improve that subfile. Under her direction the

Associateship is adding to the PDF new patterns and replacing poor

patterns with high quality data. Approximately 90 percent of the patterns,

both organic and inorganic, to be published in Section 17 of the Monograph have been designated for the FEP/CP subfile. For FY81 the group

expects to submit approximately the same percentage. The remaining ten

percent of the patterns are of less common phases of minerals, alloys,

forensic, or ceramic materials for which samples were available and

the pattern was absent or not well represented in the file.

The Associateship continues to work on methods and procedures that

are useful to the diffraction community. For instance, a considerable

amount of time is being spent on finding means of obtaining reliable

intensities. During FY80, the group began reporting a reproduci bi 1 i ty

factor for the measurement of relative intensities. This factor enables

a user of the data to evaluate the accuracy of the intensity data. Also,

in accordance with the recommendation from the American Crystallographic

Association, the Associateship now includes in its publication of data a figure of merit (FM). This FM enables one to assess the quality of the

experimental spacing measurements.

391
JCPDS Activities : NBS staff members (S. Block, C. R. Hubbard, and

A. D. Mighell) continue to participate in activities of the JCPDS. Of

particular importance has been a thorough review of the JCPDS-NBS

Research Associateship. Following this review, the RA has shifted its

emphasis to producing more high quality experimental patterns and fewer

calculated patterns. To stay abreast with the developments in automation and digital pattern analysis, Dr. N. Panagiotopoul os was hired for

the joint NBS-JCPDS diffractometer automation and data analysis project

(discussed above). To assist in the preparation, purification, and

crystallization of needed phases H. S. Parker will join the RA on a parttime basis in FY81 . The two-year goal is to increase the output and

data quality of the RA.

The Education Subcommittee (C. R. Hubbard, Chairman) has completed

a major revision of the PDF Workbook which is used at tutorials on use

of the Powder Diffraction File. This tutorial course has been presented

to about 200 di ffractioni sts at the Denver X-Ray Conference, SUNYA X-ray

Clinic, and Pennsylvania State University. The Workbook is coordinated

with the JCPDS-NBS book of high quality reference patterns.

The JCPDS Data Base Task Group (including C. R. Hubbard, Chairman,

and A. D. Mighell of NBS) has recommended to the JCPDS that they adopt

the program NBS*AIDS80 and the HP2645 CRT formatting terminal for data

entry. Both NBS*AIDS80 and the input forms for the terminal (with some assistance from the JCPDS) have been developed at NBS as a common data

input and evaluation system for Crystal Data and the JCPDS. The proposal was approved and implementation is beginning. The Metals Data

Center (NRCC-Canada) and the Cambridge Data Centre are considering

adoption of part or all of this system. The program is also being made

available to researchers and journal editors in an attempt to improve

the quality of powder diffraction patterns and unit cell data in the

primary literature. Such a program was envisioned by a subcommittee of

the American Crystallographic Association, which drafted guidelines for

publication of powder patterns.* C. R. Hubbard was one of the members

of this subcommittee.

A critical part of the JCPDS' s conversion to use of NBS*AIDS80 is

to merge and reformat their ~ 33,000 data base entries into the new data

base structure. To begin on this task the various computer readable

tapes containing portions of PDF data have been converted to a common

format, merged, and then transformed into NBS*AIDS80 input format. We

are beginning to process these through AIDS80, creating data base

entries for each PDF card. This task has been performed by E. G. Speert

a summer employee of the JCPDS under the supervision of C. R. Hubbard.

Other activities include the CIS task group (A. D. Mighell and

C. R. Hubbard), Methods and Practices Subcommittee (C. R. Hubbard),

Crystal Data Subcommittee (A. D. Mighell), and the Board of Directors

(C. R. Hubbard).

*The subcommittee's final report was presented at the IUCr-NRCC-NBS

meeting Accuracy in Powder Diffraction (June 1979).

392
Diffraction Instrumentation

Subtask 4 of Task 12153

F. A. Mauer

Equipment : During the past year, two instruments have been

installed that provide NBS with new capability for obtaining powder

diffraction data from very small amounts of material, or from a selected

area of larger samples. The Gandolfi camera, which is suitable for

examining isolated partic]es consisting of a few crystals with a total

volume of the order of 10 3 mm3

, will be used in characterizing particulates from environmental samples related to fossil fuel technology.

The Rigaku microdi ffractometer , on the other hand, is used when the

material to be examined cannot be separated from its matrix. Inclusions

in an MHD electrode or material recovered from the diamond anvil pressure cell (which cannot be separated from the gasket) would be typical

of the samples examined with this instrument. These instruments supplement the existing x-ray diffraction and SEM capabilities for analysis by

furnishing information about compound formation in minor phases or

i ncl usi ons.

Synchrotron Radiation Facilities : Scientists from NBS and from the

Naval Research Laboratory have formed a "Participating Research Team

(PRT)" for the purpose of carrying out the design and instrumentation of

two beam lines at the National Synchrotron Light Source under construction at Brookhaven National Laboratory. The facility, which is scheduled

to begin operation late in 1981, will provide an intense source ( 1

0

4 - 1

0

s higher than conventional sources) of highly collimated, polarized x-rays

in the approximate range from 6 to 25 keV (2 to 0.5A). Use of monochromators

to select appropriate wavelengths from this continuum will enable the

experimenter to utilize anomalous dispersion effects for specific elements

in order to obtain phasing information in single crystal structure

determinations or pair correlation functions in the case of glassy

materials including thin films. The intensity of the source can also be

used to reduce the time required for certain experiments that would not

be feasible with conventional sources. NBS is cooperating with scientists

at the Naval Research Laboratory in designing a monochomator system and

a general purpose goniometer that will be suitable for a number of

different types of experiments. Special detection equipment will also

be required to handle the extremely high peak counting rates encountered

in research with a synchrotron source. A decision has not yet been made

about developing a position sensitive detector system on the one hand, versus a single channel detector on the other. Meanwhile, experiments

are being planned that will exploit the unique tuneable wavelength, high

intensity features characteristic of synchrotron radiation.

A rotating anode x-ray generator, purchased in cooperation with

Division 564, has recently been installed at NBS. It has an x-ray

output ten to fifteen times greater than that of conventional x-ray

generators and will be very useful in testing and aligning experimental

apparatus for later use at the synchrotron. It will enable us to obtain

data with the diamond cell at ten times the present rate or at substantially

higher resolution.

393
Powder Materials Characterization and Analysis

Subtask 5 of Task 12153

C. R. Robbins

Refractories for Coal Gasifiers : Work with the Fracture and Deformation Division (S. M. Wiederhorn, E. R. Fuller, Jr.) in the form of

phase analysis of candidate refractories and cements for coal gasification reactor linings has been completed. Analysis was by conventional

x-ray methods on materials previously exposed to simulated gasification

environments. A final report has been prepared for the Department of

Energy. (See Task 12155)

Structural Ceramics : At the conclusion of the refractories study,

work was initiated on Si 3 N 4 , SiC, and sialons by F. A. Mauer and

C. R. Robbins. This work is now in progress. It is a continuation of

the collaborative effort with the Fracture and Deformation Division

(E. R. Fuller, Jr., R. J. Fields), and is sponsored in part by the Department of Energy. (See Task 12155). The goal is to improve the operation

of gas turbine blades and heat exchangers fabricated from these silicon

compounds

.

Characterization of Prehistoric Ceramics : A collaborative study

with the Smithsonian Institution (V. P. Steponaitis, Predoctoral Fellow in

Anthropology) of prehistoric pottery from Moundville, Alabama, has been

completed. Moundville is the second largest Mi ssi ssippian site in

eastern North America and was occupied between A.D. 900 and A.D. 1600

by Indian tribes. Quantitative phase analysis by optical and x-ray

methods has identified the raw materials used, and the range of firing

temperatures reached in making the pottery. A detailed report on the

mineralogy of the materials is planned.

Characterization of Power Plant Ash : This is a highly variable

material. Its chemical composition and physical properties are primarily

functions of fuel feedstock, variances in plant equipment, burning

methods, station loading, aging, and collection, separation, and storage

methods. Whether the ash is to be regarded and managed as a large

volume mineral resource or as a hazardous waste remains to be seen. There is an urgent need for chemical and physical characterization of

these materials.

A program to study power plant ash, sponsored by the NBS Office of

Recycled Materials, was initiated in 1979. The study will involve

development of quantitative methods of phase analysis by x-ray powder

di ffractometry and will be complemented by several instrumental methods

of chemical analysis. The work will produce a body of information on the behavior of a broad spectrum of fuel feedstocks, burned in a variety

of plants under known operating conditions. This systems approach has

not been explored before. The study will provide data needed for ash

management techniques and for a better understanding of leaching mechanisms.

It could lead to improvements in precipitator and scrubber designs, and

to better utilization of coal by-products.

394
Emphasis and resources of this project have initially been directed

toward the development of quantitative x-ray powder di ffractometry

methods. This has been possible because of a collaborative effort

between Professor R. L. Snyder of Alfred University and Dr. C. R. Hubbard

of the NBS Crystallography Group in modifying existing software in

order to utilize new, automated NBS x-ray equipment. Ancillary equipment for x-ray sample preparation is being constructed in NBS shops. It

is anticipated that the quantitative x-ray powder capability will be

available in August 1980.

Several suites of carefully selected and documented samples have

been received from interested groups for analysis. The samples span a broad spectrum of feedstock, and have been characterized by preliminary

qualitative methods.

Fossil Fuel Technology Waste Sampling and Characterization Program , Physical and Chemical Character!

- zation : In May 1980 a new program under

the sponsorship of the Department of Energy, and the technical management of the Laramie Energy Technology Center was established at NBS.

The program involves several groups at NBS and one of its objectives is

to establish the behavior of fossil fuel wastes subjected to a variety

of leaching procedures. The program will involve interaction with the

Analytical Chemistry Division. The Ceramics, Glass, and Solid State

Science Division is responsible for the physical and chemical characterization of the specimens, both before and after leaching. Receipt

of the first samples for analysis is expected in August 1980.

Emerging Technologies : On the order of forty specimens of refuse

derived fuels (RDF) have been received from the Chemical Thermodynamics

Division for x-ray analysis. This is a cooperative effort intended to

complement their calorimetric work on these alternate fuels, and to

contribute to the formulation of ASTM test procedures for these new material s.

High Pressure Research

Subtask 6 of Task 12153

S. Block, G. J. Piermarini, R. G. Munro

Activity during the last year has concentrated on three areas of

research: (1) development of a low temperature capability for the diamond

anvil pressure cell; (2) the continued search for pressure transmitting

media which will produce hydrostatic conditions at higher pressures; and

(3) the continued study of the pressure-temperature phase behavior and

electrical properties of several semiconductor materials, some of which

have potentially useful applications as high temperature superconductors

and others which are ideally suited as fixed points on the pressure scale

Low Temperature Capabilities in the Diamond Cell : To extend the

versatility and usefulness of the diamond anvil cell we have developed a new low temperature capability which permits optical and electrical

395
measurements to be made involve pressures in the 200 kbar range down to

below -160 °C without sacrificing any of its room temperature advantages.

The cooling system is relatively simple and consists of a cooling element

attached to the cell which is surrounded by a very simple insulating

box. Liquid N 2 and or cooled gaseous N 2 is passed through the cooling

element under controlled flow and temperature conditions. The temperature

is monitored continuously and to facilitate the computation and recording

of the data a microprocessor has been added to the system. The cell can

be cooled very rapidly, as fast as 15°/min. At the desired temperature

only a small flow rate is required to maintain the temperature to about

± 3 °C. Desired temperatures have been sustained for as many as four

hours without difficulty while measurements were being made. This

development represents a new and important addition to the capabilities

of the diamond cell.

Search for Pressure Transmitting Media to Extend the hydrostatic

1 imit : In our continued efforts to extend the hydrostatic limit to

improve the quality of measurements at higher pressures, we are studying

the hydrostatic properties of rare gas solids Xe and Kr by the ruby line

broadening method. In recent months much interest has been shown in

this prospect because the rare gases form very soft solids at room temperature and a few kilobars pressure. This property makes them

attractive candidates as possible hydrostatic pressure transmitting

media.

We have developed procedures which permit us to use our low- temperature system for loading rare gases in the diamond cell. The procedures

have been refined to where loading condensed gases krypton and xenon in

a diamond cell at low temperatures is now routine. Our study of Kr was interesting because a new hydrostatic limit of 158 kbar was established

(room temperature). Xenon's behavior was quite different. Low-level

nonhydrostatic effects were measured at all pressures in this material.

But an interesting observation was that the magnitude of the effect

seems to sharply decrease and then gradually build up again repeatedly

with increasing pressure. This suggests that the material is undergoing

relaxation of shear stress through plastic flow. The method offers interesting possibilities in determining the shear strength of the material. The

phase diagram of Xe was studied visually between 150° and -150° and up

to 130 kbar. No additional polymorphism appears to exist in this region

of pressure and temperature other than the solid-liquid phase boundary.

At room temperature the freezing pressure is about 8 kbar.

The low temperature system has also been used to measure the temperature dependence of the hydrostatic limit in 4:1 methanol : ethanol

.

The data show slight curvature as the glass transition pressure decreases

from 104 kbar at 24 °C to 50 Kbar at -50 °C. This latter value is con- sistent with the temperature dependence of the glass transition in alcohols.

Semiconductors : The temperature dependence of the semi conductor-tometal pressure transition in CdS was studied by our new low temperature

system down to -150 °C by both optical and electrical resistance methods.

396
The transition pressure appears to be nearly temperature independent

over this temperature range. The values obtained by electrical resistance measurements were consistently less by 5 or 6 kbar than the pressures obtained by the optical method.

Energy dispersive x-ray measurements were made on several samples

of CdS. All ultimately transformed to an electrically conducting NaCl

phase which, at least initially, was opaque. The transition pressure was found to be variable. The reasons for this effect are being investigated.

The transition pressures for the semiconductor-to-metal transformation in ZnS and GaP were determined visually in a krypton environment. The transition pressure for ZnS was found to be the same (150 kbar)

as determined in 4:1 methanol : ethanol . However, the GaP transition

pressure (235 kbar) is about 10 kbar higher than found in 4:1 methanol : ethanol

.

This effect possibly indicates that the GaP transition is lowered by the

greater stress or pressure distribution in the alcohol mixture.

Boron was investigated as allpossible fixed point standard in the

400 kbar range. However, the results with the same sample on different

runs were variable—ranging from approximately 300 to 400 kbar. Similar

results were found in another laboratory using a supported anvil press.

A possible explanation is that the transition in boron is highly susceptible

to different stress patterns. At the moment it is not a promising fixed

point. Preliminary plans are being made under the auspices of the

International Union of Crystal 1 ography , Commission on Crystal 1 ography , at

controlled temperature and pressure to carry out another round-robin

similar to that on ZnS. A candidate material is GaAs.

Theory

Subtask 7 of Task 12153

R. G. Munro

Two projects, which might be called reliability studies, are nearing completion. The projects concern the statistical reliability of

the interpretation of experimental data. One of those problems is the

reliability of binary and tertiary partial structure factors of amorphous

systems which are determined by either of two x-ray anomalous dispersion

techniques. The "direct" technique uses directly the change in the

scattering of x-rays which occurs near an atomic absorption edge. The

recently proposed "derivative" technique involves a frequency modulation

of the incident x-ray beam, which is assumed to have a tunable source

such as a synchrotron, and the slope of the atomic scattering factor.

Beginning from an ideal .system of partial structure factors, a pseudo-random number generator is used to simulate experimental error. The response to this input error is then computed. A typical example

for a binary system AB is shown in figure 6. The logarithmic axis

gives an estimate of the relative parameter error (derived from a general error matrix) for each of the three partial structure factors.

These estimates are shown as a function of the relative change in the

397
Relative

Error

of

Partial

Structure

Factor

T T

1 !

Binan/ Systm AB

Comparable Scattering Strengths

Input Error = 1%

10

!

C . ra

I ! ! ! !

.1 ,2 ,3 ,4 ,5

Relative Change of Atonic Scattering Factor

:nn
atomic scattering factors, x, under the anomalous dispersion conditions.

The experimentally accessible range of x is about OF x F° 3

. The case

shown is for two comparably good scatterers and for a net experimental

error of about 1 percent. Even under the best of conditions, the figure

shows that the direct technique cannot be expected to yield an error lower

than about 30 percent. Linder the same conditions the derivative technique

yields about 6 percent error which indicates that the experimental

development of the derivative technique is highly desirable.

The second project growing from the viscosity-glass transition problem

examines the very common problem of evaluating the parameters and A2 in the simple model y

= exp(A x + A2 x) where x is an independent variable.

The parameters are usually evaluated by means of a linearized least

squared error method. However, it is not widely known that the fitting

procedure that is used should be selected on the basis of the objective

of the least squares fit and the type of error contained in the Gata.

This work determines criteria for choosing the best least squares

fitting technique.

There are two distinguishable objectives: Obtain the best smooth

curve through the data, and obtain the best values of the parameters.

The latter case is the more complex of the two and does not have a unique solution. Consequently, criteria are obtained statistically and

with these it is possible to determine the mean RMS relative parameter

error as a function of the range and density of data. An example of

this is given in figure 7 for a simulated experimental error of 10 percent.

The numbers beside the curves give the number of decades of data.

The general conclusions that can be drawn from this investigation

are as follows: (1) The best smooth curve through the given data is

almost always given by the well known technique of using a modified

weight factor. (2) The best values of and A2 frequently do not

correspond to the smallest standard error. (3) The range of data and

the type of error determine a statistically best method for evaluating

and A2 . (4) Increasing the range of data is generally more effective

for improving the parameter values than is increasing the density of

data. (5) The use of a modified weight factor does not significantly

affect the value of the covariance matrix.

Thermal Expansion and Nuclear Solid Waste

Subtask 8 of Task 12153

T. A. Hahn

During this year, Mr. Hahn was assigned for six months to the

Office of Measurements for Nuclear Technology as technical coorainator

of a study group developing a program for DOE. The program, wnich is

described in the group's report "Measurements and Standards for Nuclear

Waste Management," will be funded in 1980 and will become an important

activity of the Center for Materials Science.

399
MEAN

RMS

RELATIVE

PARAMETER

ERROR

(p)

1,0

MODEL = EXP (Ai + A 2 x)

RANDOM INPUT ERROR = 10%

NUMBER p

2 = ( <5 A1/A1

)

2 + (6A2/A2) 2

DECADES

, 001 .

Figure 7.

2 4 6 8 10

NUMBER OF POINTS PER DECADE

400
Despite manpower limitations, measurements are being completed on a new stock of copper for SRM 736. The original material was sold out a few years sooner than had been anticipated showing the good sales of

these important SRM materials.

Initial plans were developed for hosting the International Thermal

Expansion Symposium at NBS in June of 1981. This Symposium will be held

in coordination with the International Conference on Thermal Conductivity

and the Symposium on Thermophysical Properties.

A paper, in collaboration with R. W. Armstrong (University of

Maryland) titled "Analysis of Thermally Generated Microstresses in

Polycrystalline Be Due to BeO Inclusions" was delivered at the Thermal

Expansion Symposium and will be published in the proceedings of the

Symposium. This paper resulted from the concern for the long-term

stability of beryllium used in gyroscopes where BeO is a naturally

occuring impurity. Because of the mismatch in thermal expansion,

cooling of only 200 °C could develop mi crostresses around a BeO

inclusion in a Be matrix that are equal to the yield stress of the Be

matrix and cooling over about 400 °C would be sufficient to generate

microstresses of the magnitude of the fracture stress. Also, the

plastic zone around a BeO inclusion is expected to be as large as ten

times the radius of the inclusion. These results have very important

implications on the mechanical stability and physical properties of Be

containing BeO inclusions.

Consultations continue to be offered to people trying to resolve

measurement problems or needing information on thermal expansion.

Support of ASTM activities in thermal expansion is also provided.

401

PROPERTIES, STRUCTURE, AND STANDARDS FOR GLASS AND OPTICAL MATERIALS

Task 12154

The objective of this work is to develop techniques for synthesizing

glasses and crystalline solids of special compositions, shapes, structures,

and properties; to propose and improve methods for the measurement of

chemical and physical properties of glasses and crystals in bulk and in

thin film form (e.g. , solubility in and evaporation of certain elements from

solid and liquid glasses; homogeneity and purity of amorphous films); to

study relationships between properties, structure, and constitution; to

assist the glass, and optics industries; to provide standard reference

materials of use to glass-related and other industries; to characterize

glass and crystalline materials for use as optical components and solid

state electrodes; in particular, to measure refractive index and its

change with temperature and pressure, to use Raman spectroscopy for the

analysis of crystals and thin films, and to apply light scattering and

microwave loss techniques to the detection of surface imperfections.

Vaporization from Glass Melts

Subtask 1 of Task 12154

D. M. Sanders, J. T. Wenzel, W. K. Haller

The stirrable high temperature transpirator continues to be an important tool in the study of vapor pressures over glass melts. It was developed at NBS several years ago and is the only existing apparatus

of its kind. It allows the measurement of vapor densities under true

equilibrium conditions in inert and reactive atmospheres. It can be

used with i ncongruently evaporating melts under stirred and non-stirred

conditions. Other techniques used in the project are mass-spectrometric

analysis of species from non-stirred melts, weight loss studies on non- stirred melts, and analyses of surface composition profiles. These techniques are necessary to supplement the information from the stirrable

transpirator. They also accelerate the data flow in this project which

is slow because of the nature of transpiration techniques which require

chemical analysis of high temperature condensates over long periods of times.

This year we worked principally on three different tasks. One

was the study of a boron containing system, the other was the study of

the influence of sulfur upon glass evaporation. In addition, we just

started work on the alkaline earth/alkali silicate system.

Boron Containing System . The vaporization behavior of sodium

borosilicate glass is of technological importance because both boron

and sodium have substantial vapor pressures under industrial conditions.

These vapors are corrosive to tank refractories and in addition boron

loss is of concern because of its increasing scarcity. The addition

of small amounts of boron to soda-lime-silica glass is being considered

in spite of these potential problems because it lowers the melting and

fining temperatures without changing the vi scosi ty-temperature characteristics in the glass-forming range. This could lead to substantial

403
savings in energy. 3oron is also added as a component of glasses having

superior chemical durability such as those used for medical fluid containers,

glass fibers, thermal insulation, chemical lines, and laboratory instruments.

During the last year the results of an extensive study of the

vaporization of molten boric oxide and sodium borosilicate glass in the

presence of water vapor were analyzed. It was found that in the

B2 03/H2 0 system for low partial pressures water vapor a plot of the

log of the boron pressure vs the log of the water vapor pressure was nearly linear with a slope of 1 /2 , while for higher water pressures the

slope was 3/2. This finding was consistent with a model which predicts that

HB0 2 is the predominant vapor species at low water vapor pressures

and H3 BO3 at high water vapor pressures. In contrast, no water vapor

pressure dependence was observed for a sodium borosilicate glass melt

being equimolar in sodium and boron. This suggests that a vapor species

containing sodium and boron but not hydrogen is stable in the atmosphere

above that melt. This observation is further substantiated by thermochemical calculations. A complete analysis of the vaporization behavior

in both systems was submitted for publication to the Journal of the

American Ceramic Society.

The Influence of Sulfur Upon Glass Evaporation . Another area

of continuing study was the complex interaction of sulfur and water

vapor on the vaporization behavior of soda-lime-silica glass. This study

was carried out because all these substances are introduced during

commercial production of window and bottle glass. The sulfur originates

either as a by-product of combustion of sulfur-containing fuels or is added

intentionally as a fining agent. Water vapor is a combustion product of

the flames used to melt glass.

Thermodynamic calculations and experiments were carried out in

collaboration with Dr. J. W. Hastie and Dr. D. W. Bonnell of the Chemical

Stability and Corrosion Division (561) on pure sodium sulfate liquid under

various atmospheres in a range of temperature from 1000° to 2000 °C. In

the presence of water vapor, sodium hydroxide was the predominant sodium species

Two experimental programs were carried out to determine the

accuracy of these predictions. In the first, the stirrable transpiration

apparatus (STA) was used to determine the influence of water vapor pressure

on the sodium vapor density over pure sodium sulfate liquid at 1200 °C.

The thermodynamic calculations predict an eight-fold increase in the

sodium pressure as the water vapor pressure increases from zero to 21 Torr.

This increase was not observed experimentally. A second experiment was carried out with the transpi rati on mass spectrometer (TMS). In this case

an attempt was made to observe directly the vapor species present over

a sodium sulfate liquid under the dry and wet conditions used for the STA

experiment. Again no dependence was found for the sodium vapor pressure

as a function of the water vapor pressure. Also, no sodium hydroxide gas

was observed.

In order to shed some light on this problem, an attempt was made

to find an intermediate reaction species which would lead to the calculated

water vapor dependence for the vapor pressure of sodium. It was found

404
that small amounts of sodium hydroxide added to the sodium sulfate provided

such an intermediate causing the sodium sulfate to vaporize much more rapidly and to show an increase in vaporization rate with an increase in

water vapor pressure. This small amount of added sodium hydroxide was not

depleted during the vaporization process, but rather served to convert the

sodium sulfate to sodium hydroxide vapor. This observation was verified

using the TMS, where sodium hydroxide vapor was observed until the complete

depletion of all of the sodium sulfate sample. We conclude from these

results that a kinetic barrier exists for the formation of sodium hydroxide

vapor from the reaction of sodium sulfate with water vapor. This barrier

may not exist, however, under the complex conditions found in commercial

glass-melting operations. The results of these investigations have been

submitted for publication in the Journal of the American Ceramic Society.

The Strontium-Potassium-Silicate System . Future studies in glass

vaporization are planned for the strontium-potassium-silicate system.

This system is of theoretical importance in the verification of a recently

developed multi-component diffusion theory. In collaboration with Dr. A. Cooper

at Case Western Reserve University, an attempt will be made to measure

activity data in this system. The actual experimental work will be done

by one of Dr. Cooper's students under the supervision of Dr. J. T. Wenzel

or Dr. D. M. Sanders.

Other Chemical and Physical Properties of Glass

Subtask 2 of Task 12154

D. J. Cronin, W. K. Haller, D. H. Blackbrun, J. T. Wenzel,

D. A. Kauffman

Nucleation Kinetics in Lithium Silicate Glasses . Nucieation processes

are of interest in glass because it is the absence of nucieation and/or

inhibited crystal growth which allows glass formation. Furthermore,

glass-ceramic materials require controlled nucieation and crystal

growth for their synthesis. A study of the nucieation kinetics of

lithium di silicate glass as a function of platinum concentration has

been started to help elucidate the heterogeneous nucieation mechanisms

in glass in general and specifically to investigate the apparent anomalous

nucieation behavior when using platinum as a catalyst. Information in the

literature shows there is one concentration of platinum which is most

effective in bringing about volume crystallization. Such an effect would

not be expected from nucieation theory.

Lithium disilicate glass is being studied since it is a wellcharacterized system and it has some practical interest as it forms

the basis for several families of glass ceramics. The project is

being carried out as time permits and with the partial assistance

of a student during the summer (D. L. Swerdlow).

Cooling Induced Luminescence of Rare-Earth Phosphate Glass . In

the process of producing a terbium phosphate glass it was observed that

on casting the melt into a metal mold an intense green emission was produced. Subsequent spectroscopic measurements showed a similar effect

405
in europium phosphate glasses though the emission is in the red portion

of the spectrum thus making visual detection difficult because of the

background from blackbody radiation.

An investigation has been carried out to determine the nature

of the excitation mechanism. Spectra of the terbium emission show lines

characteristic of terbium fluorescence. An obvious possible excitation

mechanism involves excitation by the UV component of the blackbody radiation

since it is observed that emission can be excited, weakly, in a room temperature sample by blackbody radiation from the furnace. However, other

data suggest that this mechanism cannot account for the observed emissions.

The emissions are observed only on rapid cooling of the sample never in

a steady state situation.

The emissions are not sensitive to minor changes in terbium

concentration; however, additions of other ions, such as cerium (but

not magnesium) quench the emission on cooling but do not effect fluorescence

under uv radiation at room temperature. The sensitivity to variabl e-val ence

ions suggests the possibility of a temperature dependent valency to excite

the fluorescence spectra of the terbium.

Data analysis is continuing in an attempt to determine the

excitation mechanism. Figure 1 shows the luminescent spectrum of the

terbium phosphate melt at successive stages of thermal quenching.

Viscosity in the Mg0-CaQ-Al ?0 3

- Si0 ? System . This work is being

carried out in collaboration with Dr. C. M. Scarfe of the Geophysical

Laboratory of the Carnegie Institution of Washington and the University

of Alberta. The system is of interest for a variety of reasons. It is

important to geologists because it represents mixtures of two of the

three minerals that form the basis of basalts. The system is also with

study from the viewpoint of glass technology since it is alkali-free

and stable glasses can be produced within the system. These glasses are expected to have several desirable properties such as good chemical

durability and high elastic modulus and could be of commercial interest

to fiber glass reinforcement of plastics, concrete, and metal. Certain

glasses in the systems, those requiring low processing temperatures,

might also be of interest in nuclear waste applications in the future.

Accurate viscosity data are needed for future processing considerations, to allow accurate modeling of geologic systems, and to aid

analysis of melt structure studies. Results of the experiments

have shown that published viscosity data on this system are considerably

in error as had been suggested in the recent literature.

The viscosity data also indicate the possibility of significant

structure changes occurring in the melt as MgO is replaced by A1 2 0 3

. Work is continuing to clarify this point.

Dynamic Synchrotron SAXS Investigation of L/L Phase-Separation . Metastable liquid/liquid phase-separations have been the subject

of many studies in the past year. Due to the high viscosity of undercooled

406
Figure 1. Luminescence Spectrum of Terbium

Phosphate Glass at Successive Stages of

Thermal Quenching.

A1ISN3Q Wild 3AI1V13EI

625

585

545

488

436

412

WAVELENGTH

(nm)
melts, the phase separation proceeds relatively slowly and can be frozen

in at various stages of the process. Thus, glasses have become popular

experimental models for phase separation in condensed systems in general.

Although the use of such glass systems has greatly contributed to

the understanding of phase separation, there remain several theoretical

questions concerning the very early stages of phase separation. Techniques which yield detailed morphological information (Transmission

Electron Microscopy) have, in the past, been applied only to quenched

samples. Dynamic observation of xray scattering patterns during cooling

into a miscibility gap have so far been hampered by the need for long

exposure during which devitrification interferes. Such observation

would give information about the decomposition process in a regime

where theoretical predictions are simplest and reflect the underlying

fundamental thermodynamics in the clearest manner.

The recent availability of very high xray intensities at synchrotron

ring facilities, promises reductions in exposure time for small angle

xray scatter analysis. In a collaborative effort with G. B. Stephenson

and A. I. Bienstock of the Stanford Synchrotron Laboratory, we plan to

investigate early stages of phase separation in the Na2 0-B 2 0 3 -Si0 2 system. If necessary, other systems will also be investigated. Preliminary experiments with phase separation and quenched samples were undertaken. It appears that with the present position sensitive scintillation

detector array features around 100 A will be detectable in a minimum

counting time of one second. For features smaller than 100 A, the scatter

intensity was too low for efficient counting and background resolution.

Figure 2 shows a plot of count rate versus detector position for a glass

sample with a characteristic phase-separation domain dimension of 350 A.

Work in the near future will consist of the construction of our on-line sample furnace (platinum strip type) and in improvements in the

counting system.

Glassy Multicomponent Films

Subtask 3 of Task 12154

0. M. Sanders, E. N. Farabaugh, M. E. Wilke (S. A. Hurwitz,

R. Rodriquez)

In this fiscal year we have continued to construct a facility for

the vapor deposition and i_n situ analysis of films. The system has

several unique features. It has the ability to codeposit films from

several atomic beams with independently variable beam intensities.

After deposition, the films can be transferred, i_n vacuo , into an analysis chamber and subjected to a wide variety of instrumental analysis

techni ques

.

The system was specifically created to produce noncrystalline films over a wide spectrum of compositions. It furthermore allows the production

of films with composition gradients. It is planned to be used in general

with studies of the glass structure and in investigations of thin films

408
SAMPLE

F

-

BACKGROUND

<S5 O <S

<S3 © G3

10 Q LO

SINn03

Figure 2. Synchrotron SAXS of Microphase Separated Glass of 330

Characteristic Dimension

200

300

400

POSITION

ALONG

DETECTOR
in application where the absence of crystalline grain boundaries promises

to have particular advantages. A schematic of the system is shown in

figure 3. In the past year, the facility has been made operational,

although several parts of it still have to be acquired.

Non-Crystalline Optical Coatings . One area of our glassy film work

deals with the synthesis of optical films which are free of grain boundaries found in the usual optical coatings. It is hoped that such films

will show improved superior resistance to intense laser radiation. This

work is carried out in cooperation with Lawrence Livermore Laboratories.

Results of this work will also be important to optical waveguide technology.

Homogeneous films of MgO and Mg0-Si0 2 composition were produced by

codeposition from separate MgO and Si0 2 molecular beams. The source materials were electronbeam heated. The deposition rates were monitored

by individual quartz crystal thickness monitors.

Using xray diffraction techniques, it was shown that the degree of

crystallinity of the MgO films was dependent on substrate temperature

and also on the amount of a glass-forming constitutent (Si0 2 ). Polycrystalline MgO films could be made amorphous by the addition of as little as 25 percent Si0 2 during film deposition. Proceeding forward

at the same time is the study of different substrate cleaning techniques

which are essential if high quality films are to be produced.

BK-7 glass substrates were subjected to various cleaning procedures

before loading into the deposition chamber loadlock. Once in the

loadlock they were cleaned by a glow discharge, moved to the deposition

position, and heated to the desired temperature prior to deposition.

Substrates were characterized by Electron Spectroscopy for Chemical

Analysis (ESCA) after every stage of the preparation procedure, in

order to evaluate the ability of these cleaning steps to remove surface

contamination. Characterization by ESCA demonstrated that the hydrocarbon

residue was removed from substrates by cleaning with a glow discharge

for one and one-half hours.

Thin Film Stress Corrosion . During the last year an attempt has

been made to identify the stressrel ated reactions leading to delayed

fracture phenomena in ceramic materials. In this study ceramic films

are prepared by physical vapor deposition in an ultrahigh vacuum environments, subjected to varying levels of stress by deflecting their substrates, exposed to well-defined amounts of corrosive atmospheres such

as water vapor, and analyzed for resulting reactions using the surface

analysis techniques available in the thin film facility. These include

Electron Spectroscopy for Chemical Analysis, Secondary Ion Mass Spectroscopy, Ion Scattering Spectroscopy, and Auger Electron Spectroscopy . It

is hoped that in this program the stress-enhanced reactions which lead

to delayed fracture in ceramic materials can be identified.

In order to determine which ceramic system-analytical technique

combinations have the highest probability for observing stress-enhanced

chemical reactions, single crystals of wide variety of ceramic materials

410
DEPOSITION

CHAMBER

ANALYTICAL

CHAMBER

411

I

igure

3.

Schematic

of

Glassy

Film

Synthesis

and

Analysis

System.
i

will be scratched and analyzed under ultrahigh vacuum conditions to

characterize the unreacted surface. The pristine surfaces produced by

the scratching procedure can then be reacted in a well defined manner

using a doser developed at the National Bureau of Standards by the

Surface Analysis Division. The ceramic composition, analysis technique

combinations which show the greatest promise will then be prepared in

the thin film form for the stressrel ated reaction studies described in

the last paragraph. This work is being carred out in conjunction with

the Fracture and Deformation Division (562).

Protective Films on Metals . Most non-noble metals, when exposed to

the atmosphere, acquire a film of metal oxides or hydroxides. In some metals such as aluminum or stainless steel, such films protect the

metals from further corrosion by water or the atmosphere. It has been

found that most of the good passivating films are amorphous in nature

and it was speculated that it is the absence of grain boundary diffusion

which makes these films superior to polycrystall i ne films.

While it is useful for a film to have an amorphous structure, it

is not necessarily sufficient. For example, the silicon dioxide films

formed by thermal oxidation of silicon form effective diffusion barriers

while films of silicon dioxide prepared by physical vapor deposition do

not appear to be effective in inhibiting corrosion. It has been suggested

that the existence of strong short-range-order in the former case may

explain this difference in protective behavior.

An alternative explanation involves a difference in the density of

a passive film compared to its non-passive counterpart. Other factors

could be the anisotropic compressive stresses produced by "stuffing" new atoms into the surface structure and the presence of chemically combined

water normally found in the passive film structures.

In order to shed some light on this problem we propose to deposit

iron-chromium alloy films in the range from 0 to 24 mass percent Cr on iron substrates using our deposition system. By codeposition, we can vary the film concentration over this range in small increments and

analyze the resulting metallic films in the Surface Analysis Facility

prior to exposure to oxidizing conditions. We then plan to oxidize

these films with varying amounts of water vapor to determine the influence

of water vapor content on the passivation nature of these films. The

variation of oxide film composition as well as the presence of water

vapor are parameters which have potential effect both on the structure

and the passivation characteristics of the films. We can also oxidize

the films electro- chemically and compare those films with the ones formed by straightforward thermal oxidation.

The resulting films can then be characterized using the Surface

Analysis Facility for the nature of the bonding in the passive films,

the composition of those films (including hydrogen content), and the

change in that composition as a function of distance from the surface

of the film. We plan to determine the degree of ordering of the films

using electron diffraction by depositing the films on el ectrochemically

thinned substrates.

412
Finally, the films will be characterized as to their ability to

protect the highly reactive iron substrate using electrochemical techniques.

A correlation will be made between the film structures produced by

different methods of preparation and the ability of the films to protect

the substrate.

These experiments can then be repeated by directly depositing

oxide compositions (for instance, iron and chromium oxides) using electron

beam coevaporation. We can then correlate the structures of the resulting

films with the ability of these films to protect the substrate. As

before, we will have a series of films prepared in different ways, with

presumably different structures which can be correlated with their

passivation characteri sties.

From these studies we hope to determine those characteristics

which are critical in the formation of passive films and, in addition,

identify possible alloying agents which increase the effectiveness of

passive films. If, for instance, we find amorphous films having strong

local ordering to be character!* stical ly more effective passivation

agents than their polycrystalline counterparts, we would find alloying

agents which can be added to the metal in small quantities to produce

such superior amorphous passivation films.

The above described project has recently been initiated. Prel i mi nary

to the production of actual films, we are presently practicing the

evaluation of protective films by electrochemical means on metal pieces

having the configuration of the future film targets. This project will

be carried out in cooperation with the Chemical Stability and Corrosion

Division (561).

Standard Reference Materials for the Glass Industry

Subtask 4 of Task 12154

M. J. Cellarosi, D. J. Cronin, W. K. Haller

Glass Liquidus Temperature SRM . The certificate for this SRM was published this year, and the soda-lime-silica glass representing the

standard (SRM 773) is now on sale. This standard was developed in the

past years and a full description of its nature and uses can be found in

previous reports.

This SRM is especially important to the glass industry for checking

test methods and to calibrate equipment for the determination of the

Liquidus Temperature of Glass by the ASTM C829 Gradient Furnace Methods.

SRM 773 will also aid industry in research and for development of new

glasses. This is because devitrification is a chief factor which limits

the composition range of glasses. Importantly, this standard will help

energy conservation efforts through optimization of furnace, working,

and annealing temperature systems.

Viscosity SRM . The viscosity of a is routinely determined in

commercial production facilities as a reliable process control indicator.

It is also frequently measured in the research laboratory as a parameter

413
to be correlated with other chemical and physical properties of glasses.

Viscometers are generally calibrated using standard reference glasses.

Due to the wide variety of glasses used in industry, standards covering

a wide range of viscosity values are included in the NBS SRM catalog.

The SRM's are in most cases used once and discarded, thus requiring

restocking periodically.

In the near future it will be necessary to restock one of the more popular SRM's, 710. As part of this effort a new precision melt viscometer

is being constructed to assure the best possible calibrations. In fiscal

year 1979, design of the viscometer was completed and equipment received

was found to be satisfactory. In fiscal year 1980, the major elements

of the instruments were constructed and preliminary calibration runs were performed. Silicone liquids were obtained, and the viscosity

determined by Dr. J. Phillips of NBS. The liquids are to be used in the

final calibration of the instrument. The furnace and temperature control

part of the equipment will be built during the next fiscal year; thereafter

the glass procurement process can be started.

Dielectric Constant SRM . This project was initiated on recommendation of ASTM Committee C-14.04 (Physical and Mechanical Properties of Glass).

This SRM activity is needed to upgrade, standardize, and calibrate the

measuring systems for dielectric constant of glass employed by both producers and users of glass. This need was documented by a survey conducted

by NBS on behalf of ASTM.

Glass, in general, as an insulating material is used extensively in

electrical /electronics applications in two distinct ways:

(1) Glass is used to support and insulate components of an electrical/electronic network from each other and from

ground. Examples of such applications are: envelopes

for devices, substrates, windows for electromagnetic

waves, encapsulation, insulation, etc.

(2) Glass is used to function as a dielectric of a capacitor.

For the first use, it is generally desirable to have the capacitance

of the support as small as possible. For the second use, a high dielectric

constant value is preferred so that the capacitor may be physically as small

as possible.

NBS heads an ASTM task force of industrial laboratories for interlaboratory comparisons activities, for studies on techniques that increase

test precision, and to develop standard methods.

During FY 1979, sets of measurements were carried out with glass

SRM 711 samples, and procedures proposed and distributed by NBS. This

activity is now in progress with more laboratories expected to gear up for

participation. Thus far, the agreement in the reported data is excellent

with a maximum spread in the data of less than three percent.

414
NBS measuring techniques utilize guarded electrodes (i.e., threeterminal configuration). A new test cell/fixture was designed for this

purpose to minimize errors due to inductance/resi stance and stray capacitances. These techniques were accepted by ASTM for further evaluation.

SRM-Liai son . The Glass Group maintains effective relations, with

the glass industry, R&D organizations, and academia concerning the

progress of science and technology in the field of glass. Active participation is extended to various ASTM committees and other standards

bodies.

Plans for Future SRM's . Melt Resistivity . Accurate melt resistivity

data are necessary for the design and equipment specification for electric

melting furnaces. With the prospect of oil and gas shortages and increasingly stringent air quality regulations electric furnaces are receiving

more attention than in the past. This attention has also generated an interest in more accurate measurements of melt resistivity and hence, a consideration of an SRM for this property. In FY79, NBS conducted an ASTM round robin testing program on glass resistivity versus temperature

in the molten range. NBS distributed samples of SRM 710, procedures,

and performed data analyses. The results of this round robin were encouraging but not without concern, especially in the very high temperature range. Therefore, further research on procedures and methods is

warranted in this area.

Melt Density . There is some interest in the glass industry in

having an SRM certified for melt density. Melt density is of importance

to those designing and modeling glass-melting furnaces. Melt density

information, along with an assumed or measured temperature distribution,

allows estimation of the nature of convection flow patterns in the tank.

Thermal Expansion Coefficient . There has been an interest expressed

by members of the glass industry and university laboratories in a glass

SRM having a thermal expansion coefficient in the range of 90 to 100 x

10 7 /°C, the range of the majority of commercial glasses.

Analytical Glass Standard Reference Materials

Subtask 5 of Task 12154

D. H. Blackburn, D. A. Kauffman

A large number of complex glasses were synthesized for analytical

reference material purposes. These were either in the shape of blocks,

fibers, or spheres, or they were cast into source blocks used for producing

thin films by sputtering. The synthesis and shaping of these glasses

requires extensive experience in glassforming systems and in glass

technology. Glasses have become the mainstay of the NBS SRM program for

analytical instrumental analysis. The following types of standard

reference materials were prepared in the last year.

Glass SRM's for Small Particle Analysis . This work has had considerable impact in the development of quantitative analysis methods for

electron probe microanalysis and secondary ion mass spectrometry . Past

415
work has resulted in the issuing of Research Material for Microchemical

Analysis No. 30 which consists of ten glasses in bulk form and Research

Material for Microchemical Analysis No. 31 which are the same glass

compositions in the form of fibers in the four to ten micron diameter

range. Work is nearing completion in the issuance of 15 glasses as Standard Reference Materials for Microchemical Analysis that have a certified chemical analysis. New glasses have been developed with

different matrices which contain up to 20 different elements. Stable

halogen-containing glasses have also been prepared. In continuation of

work which led to the development of Mineral Glasses for Microanalysis

SRM 470, asbestos mineral glass analogs have been produced for the

minerals anthophyl 1 i te and crocidolite. The most ideal shaped particle

for microprobe analysis standards is a sphere. In the past year, new

and more efficient equipment has been constructed to produce spheres

from less than a micron to 50 microns diameter. Glasses, in the future,

will be available in the form of cubes, fibers, or spheres. Further

expansion of this work will require glasses that contain moderate amounts

of uranium and thorium oxide. Due to toxicity and radiation hazards, a separate facility is to be built with an absolute filter incorporated in

the ventilation system. This facility is in the planning stage and will

require new glass-melting facilities as well as associated equipment

needed for glass batch handling and sphere and f i ber-formi ng apparatus.

This work was done in cooperation with several groups in the Center for

Analytical Chemistry.

Thin Glass Film Standards for Calibration of X-ray Fluorescence

Spectrometers . One of the most promising techniques for preparing thin

film calibration standards for x-ray fluorescence spectrometry has been

by sputtering glass, using a focused ion beam device. Considerable

work has been done using this procedure and has been described in

detail in NBS/EPA Energy/Environment Reports, the latest of which is

entitled: "The Development of Potential Thin Standards for Calibration

of Xray Fluorescence Spectrometry. " The films can be deposited on practically any desirable clean substrate such as polycarbonate, and

exhibit great adherence to the substrate obviating the need for over- coating the film to ensure integrity. The ion sputtering device requires

a seven-inch diameter glass disc for the target. Special glasses have

been developed containing the appropriate elements of analytical interest.

(See table 1.) This requires a considerable amount of experimental

glass preparation since the glass must be stable and durable and contain

the elements of interest in sufficient quantities for adequate fluorescence

and yet not contain elements which will give interfering and overlapping

lines in the x-ray spectrum.

416
Table 1. Composition of Six Thin Glass

Fluorescence Standards

Films to be Used as X-ray

Wt Percent

Si 0 2 40 36 36 45 40 39

A1 2 O 3 10 13.5 8

CaO 10 18 18

Fe 3 0 4 10 13.5

Na2 0 5 35

PbO 20 26 20

Mn0 2 10 2

V2O5 5 2 k2 o 10 10

ZnO 20 10 8

MgO 9 12

Na^SO* 20

T i 0 2 10 5 NaP0 3 30

A1(P0 3 ) 3 70

CO 2 O 3 2

CoO 2

Glass Target (SRM 477) for Calibration of Semiconductor Energy

Dispersive X-ray Spectrometers . Work has been completed on this project.

A glass designated as SRM 477 will soon be available as an NBS Standard

Reference Material. The glass will be issued in the form of 25 mm diameter discs which are 3 mm thick. Three hundred and fifty of these

discs were prepared and delivered to the Office of Standard Reference

Materials for issue. This glass target in conjunction with an annular

source of 55 Fe and positioning apparatus (see figure 4) makes it possible

to measure window absorbtion and other losses in semiconductor x-ray

spectrometers. A publication in progress entitled "A Standard Technique

for Measuring Window Absorbtion and Other Efficiency Losses in Semiconductor

Energy Dispersive X-ray Spectrometry" will explain the procedure in

detail. The test procedure is also available from the Nuclear Instruments

and Detector Committee of the IEEE Nuclear Science Society, entitled

Standard Test Procedures-Semi conductor X-ray Energy. The procedure is

to become an ANSI/IEEE Standard and an International Electrotechnical

Commission Standard. This work was coordinated at NBS by Louis Costrell

for IEEE.

Thin Glass Film Standards for Analytical Electron Microscope . For the calibration of the x-ray fluorescence and energy loss modes

in analytical electron microscopy, a special glass containing Si0 2 , P 2 O 5 , CaO, AI 2 O 3 , MgO, and six transition element oxides was prepared in

the form of a seven-inch diameter target for large scale focused-ion beam

sputtering. The sputtered films will be approximately 0.5 microns thick

and will be supported by a carbon film on a standard electron microscope

grid. A large number of these standards can be prepared in a single

sputtering cycle when using a seven-inch target thus assuring uniformity

among the standard films and eliminating reproduci bi 1 i ty problems which

would be created if a number of cycles were necessary.

417
Standard Glass, NBS SRM-477

(

Figure 4. Apparatus for Window Thickness Measurements

with a Glass Fluorescent Source.
Isotopic Glass Standards for Micro Mass Analyzers . Various

sophisticated analytical instruments are capable of isotopic analysis.

Instruments such as the ion microprobe analyzer and new instruments

such as the Leybold Laser Microprobe Mass Analyzer and Camera Ion

Microscope are all designed for mass analysis. Isotopic standards are needed for these instruments. Preliminary work has been done in the

preparation of isotopic lead-silicate glass spheres. Since isotopic

lead is quite expensive only gram quantities of glass will be prepared.

This required a new apparatus which has been designed and constructed

to produce and recover spheres from small amounts of glass. The apparatus

operated successfully and spheres in the 1 to 30 micron range were produced from a lead-silicate glass prepared from natural lead oxide.

Special Glasses (Laser Glasses)

Subtask 6 of Task 12154

D. H. Blackburn, D. A. Kauffman

In continued collaboration with laser research projects at

Lawrence Livermore Laboratory, glasses were prepared for the study of

the fluorescence behavior of ions in a wide variety of amorphous host

environments. Approximately 50 successful glasses were prepared. The

glasses involved the introduction of rare earth and transition metals,

in varying concentration, into different glass matrices (e.g., silicate,

borate, phosphate, and telluride).

Resource Recovery and Utilization

Subtask 7 of Task 12154

M. J. Cellarosi

This project is being 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 for materials recovered from wastes.

In the area of glass, the Glass Group is carrying out cooperative

activities with ASTM Committee E-38 on Resource Recovery, the glass

industry, and reclamation facilities, to write test procedures, methods,

and specifications for recovered glass. These activities are primarily

directed toward the reuse of reclaimed glass in container manufacturing.

Container glass manufacturers use cullet (broken glass) as a percent

of the charge to their furnaces. This long-established practice promotes

the melting of raw materials and permits the reduction of furnace

temperatures. Most of this cullet is scrap glass from the manufacturing

plant itself.

A potential new source of cullet for container manufacture is the

glass contained in the municipal solid waste stream. The amount of glass

in this stream is estimated to be 10 to 12 percent. Most of this glass is

soda-lime glass, which is the same type used for bottles and jars.

Glass recovered from municipal waste is considered to offer the potentials

419
for increasing the amount of cullet charged to the glass furnaces. The

resulting benefits of such practice, would translate mainly into energy

savings and extension of furnace linings life.

As of this date, several large-scale reclamation facilities have

been built. Others are being constructed now, and more are planned.

These facilities will separate the various components in the municipal

solid waste stream. Current projections are that these plants will

reclaim high quality glass, and place it in the marketplace at prices

competitive with the raw materials it replaces.

During the year, NBS, ASTM, industry, and resource recovery interests

have cooperated in finalizing two standards. These apply to waste glass

as a raw material for the manufacture of glass containers. The standards

are identified as: ASTM E708-79 (Specifications) and ASTM E688-79 (Test

Methods).

Both designations refer to mixed color glass recovered by froth

flotation techniques. They provide the means for determining whether

the waste glass is suitable for use in manufacturing. These standards

are a first step in promoting significant participation by all interested

parties, especially the intended users.

The test methods combine visual examinations as well as sophisticated

chemical and physical tests. These cover moisture contents, particle

size, magnetic/nonmagnetic contamination, off-color glass, organic and

inorganic contamination, and melt evaluations.

In FY 1979, our laboratory carried out several tests and melts on initial samples from two resource recovery plants. Results showed unacceptable

quality in terms of magnetic, nonmagnetic, and inorganic contaminations.

However, these results are not indicative of future production as the

plants are in start-up phases and modifications are taking place to reduce

contaminant levels. Especially important in this respect are efforts to

reduce contamination by non-glass particles or refractori es . Refractories

in certain size ranges will not melt in the glass furnace. Such particles

are the source of stones in the glassware and the product must be rejected

for aesthetic reasons or structural weakness. The latter is an important

consideration in minimizing safety hazards, especially for carbonated

beverages containers.

NBS is currently cooperating in ASTM activities to develop specifications

and test methods for color separated glass. The new $80 million recovery

plant at Hempstead, New York, employs modules that separate glass by colors

(i.e., flint, amber, and green). This is an important project as color

has been identified a major barrier to recycling. The plant is projected

to produce 500 to 600 tons per week of color separated glass. Oxides of

iron and chromium are the main coloring agents used in glass container

manufacture. For example, concentrations of Cr 2 0 3 by weight percent

are: 0.0015 (flint), 0.025 (amber), and 0.27 (green). Therefore, only

minute quantities of amber or green colored glass can be accepted in flint.

420
Other NBS activities involve participation in correlation studies

with actual production processes. This project was started this year,

and involves a glass container manufacturing plant in Dayville, Connecticut, and the glass recovered at the Hempstead Resource Recovery

facility. This work is very important in establishing firm specifications for a material which the glass industry has no prior experience

with. So far, this effort has not progressed very well, mainly because

of labor, technical, and environmental difficulties at the Hempstead

Plant.

Optical Properties of Materials

Subtask 8 of Task 12154

A. Feldman, M. I. Bell, R. M. Waxier, M. J. Dodge

Piezo-Optics : During the past year the infrared dispersion of

stress-induced birefri ngence has been studied in CaF 2 , SrF 2 , and BaF 2

. We have observed, for the first time, the strain-induced splitting of

the infrared-active transverse optic-phonon (IR-TO) mode of an ionic

material in which the mode is Raman- forbidden. In fluorite structure

materials, there exist two triply degenerate transverse-optic (TO)

modes, an infrared active (IR) mode which is Raman-forbidden, and a Raman-active mode which is IR- forbidden. (This is in contrast to the

zinc-blende structure in which there is a single, triply degenerate, TO

mode, which is both IR- and Raman-active.) The effect of a stress on these modes is to lift the degeneracy of the modes. Until now, workers

have been able to measure only the stress-induced splitting of the Raman

mode but have been unable to obtain the splitting of the IR mode.

A year ago, we reported on preliminary measurements that had shown

a large dispersion in the coefficients for stress-induced bi refri ngence.

This past year, we have obtained sufficient data to perform a least

squares fit of the data to a strain-dependent oscillator model associated

with the IR-TO phonon. In figure 5, we show the experimental data

obtained, denoted by the data points, and the least squares fits, denoted

by the solid curves. The fit is quite good. Notice the large dispersion.

In fact, the coefficient K 44 of CaF 2 and SrF 2 reverses sign at the

longest wavelengths.

The principal conclusions of this work are:

1. The alkaline-earth fluorides CaF 2 , SrF 2 , and BaF 2 show a large

infrared dispersion in the stress- i nduced bi ref ri ngence.

2. The data can be fitted to a strain-dependent oscillator model

associated with the infrared active TOphonon.

3. The shear deformation potentials which give the splitting of the

IR-TO mode per unit strain, have been obtained.

4. The strai n- i nduced oscillator strength anisotropy appears to be

negl igible.
2 6 10 WAVELENGTH (jim)

Figure 5. Photoelastic constants of CaF 2 , SrF 2 , and BaF 2 derived from piezo-bi refri ngence

data. The curves are least-squares fits of the data points denoted by pulses for k 1: -k 12

and squares for k 4 u, to a stressed-osci 1 1 ator equation. The circles and triangles represent

our data that were not used in the fit. The x's and diamonds are data derived f rom the work

of others with a sign reversal on the k 44 data to provide better agreement with our data.

422
5. The splittings due to [100] stress and [111] stress are of opposite

signs and make contributions of opposite sign to the bi refringence.

6. Comparison of the IR-TO deformation potentials with the Raman

deformation potentials shows certain significant differences.

NML Topical Conference on Basic Optical Properties of Materials : A topical conference on Basic Optical Properties of Materials

sponsored by the National Measurement Laboratory of NBS in cooperation

with the Optical Society of America was held May 5-7, 1980. There

were 122 registrants from universities, Government, and industrial

research laboratories throughout the United States and more than a dozen

participants from foreign countries. The purpose of the conference was

to discuss the state-of-the-art in the measurement and theory of optical

properties of materials of importance to advanced optical technology;

that is, the conference emphasized the science of optical materials in

bulk, thin film, and fiber form rather than optical devices as such.

The response of the participants to both the content and organization

of the Conference was highly enthusiastic. The topical areas covered,

as listed in the program were: nonlinear optical properties, ultraviolet properties, infrared properties, graded index materials, inhomogeneous materials, thin films, optical fibers, planar optical waveguides,

and external influences including piezo-optics, thermo-optics, and

magneto-optics. Papers dealt with many aspects of optical absorption,

reflection or refraction caused by electronic and phonon transitions in

different regions of the optical spectrum and how these processes are affected by external influences. A significant aspect of the Conference

was the ever-i ncreasi ng variety of measurement methods for characterizi ng

optical properties. For example, new techniques, such as integratedoptics, guided-wave methods and vacuum calorimetry, and highly refined

older techniques, such as spectroscopic ellipsometry and differential

reflectometry , demonstrated the large advances in characterizing dielectric

and metallic thin films and surfaces. The results of optical materials

research will be important for many technological applications such as communications, signal processing, solar energy conversion, laser fusion,

chemical spectroscopy , and optical displays.

NBS Special Publication 574 contains summaries of 62 papers presented

at the Conference.

Refractive Index : Precision refractive index (RI) measurements have

been made for NBS and industrial users. The final analysis of the RI data

obtained for the Vee-block prisms, reported in 1979, was completed. The

data were then used to calculate the tables which are necessary for the

Vee-blocks to be incorporated into Vee-block refractometers used for

precision ref ractometry . Measurements on SRM 1823, "Refractive IndexGlass," were completed and the data were turned over to OSRM for analysis

and completion of the certificate. Measurements have been made on eight

sucrose solutions, four samples of iso-octane, and four samples of

toluene. These liquids will all be used for some type of SRM other than

RI , but the RI at various temperatures and wavelengths has to be known.

423
Other work on refractometer test plates has been performed as necessary.

A paper entitled, "Refractive Properties of Magnesium Fluoride," by

Marilyn J. Dodge, was presented at the annual meeting of the Optical

Society of America in Rochester, New York, October 1979.

Raman Scattering : The gradual automation of the NML Raman Spectroscopy

Facility has continued, with hardware being added to the computer system

as rapidly as supporting software could be developed. This year's major

addition, a digital plotter, called attention to a serious weakness in

the system: it's low speed in manipulating large data arrays when

programmed in BASIC. Rather than give up the flexibility and ease of

programming inherent in this language, we have developed a package of

machine (assembler) language routines which can be invoked from BASIC

and which provide capabilities for high-speed manipulation of large

arrays. With these routines, many of the operations required in displaying and manipulating spectra (e.g., scaling, smoothing, background

subtraction, finding sums, differences, or ratios) can be done at speeds

limited only by the display hardware. These programs have aroused

considerable interest among other NBS users of the Interdata 7/16

computer, and will soon be available for general distribution.

Our studies of ion implantation and anneal i ng of semiconductors

have continued in collaboration with R. A. Forman, D. R. Myers, and

D. Horowitz of the Electron Devices Division. We have found that

previous studies in which measurements of the local mode produced by the

impurity were used to estimate the degree of electrical activation of

born ions implanted into silicon were seriously compromised by failure

to take into account the presence of a combination band due to the host

lattice. This band coincides almost exactly with the local mode of the

1:L B isotope, and its observation can lead to the impression that annealing

has been successful when this is not the case. This problem was clearly

demonstrated by comparison of the spectra of unimplanted waters with

those of well-annealed samples containing 13-B and 10 B. A note describing

these measurements has been prepared for submission to the Journal of

Applied Physics. Another series of measurements was made in order to

compare the results of laser annealing with those obtained by thermal

annealing. Although the quantitative analysis of these data is not yet

finished, an important qualitative result is that with proper selection

of annealing conditions laser and thermal methods can yield samples with

identical Raman spectra. All previous work known to us has indicated

significant differences for which only tentative explanations could be

offered. Examination of the annealing conditions necessary to achieve

this result, correlation of the spectroscopic effects of laser annealing

with the resulting surface morphology, and possible implications for

semiconductor processing technology will be discussed in future publicati ons

.

In connection with studies of implantation damage, annealing, and

expitaxial growth, it is important to understand the effects of strai

n

and temperature on the 1 atti ce modes of semi conductors and on the local

modes due to impurities. As a first step, a model for the anharmonic

lattice dynamics of di amond-structure crystals due to Keating (with

refinements by Martin, Fuller, and Bell) has been extended to include

the effects of ionicity (charge transfer) which occur in the zinc-blende

424
structure or when a donor or acceptor impurity is introduced. The model

accounts well for the strain dependence of the transverse optical frequencies

in all semiconductors for which experimental data are available, and

these results were presented at the VUth International Conference on Raman Spectroscopy, Ottawa, August 4-9, 1980. It appears that a very

similar model can be applied to crystals having the fluorite structure,

and calculations are in progress with the aim of providing a unified

explanation of the results of Raman scattering measurements and those

obtained by Feldman and Waxier using infrared piezo-birefri ngence.

A brief series of measurements was carried out in collaboration

with G. Birnbaum and H. G. Sutter (Office of Nondestructive Evaluation) and

M. Zoppi (University of Florence) to examine col 1 ision-i nduced scatteri nq

i n sul fur hexafl uoride at high density. In order to obtain the densities

required, a system was constructed which permits operation above the

critical temperature of 45.6 °C. An optical chopper and appropriate

software were added to permit automatic background subtraction, and with

this equipment excellent depolarized spectra were obtained in runs of 12 to

60 hours. Data were obtained over the density range of one-tenth to

three times the critical density, and analysis of the density dependence

of various spectral features is now in progress. An important preliminary

result is that scattering in the region from 100 to 140 cm 1 which had

previously been regarded as evidence of a failure of the first-order

dipole-induced-dipole (DID) scattering model is in fact due to the

presence of at least two hot bands in this region. Careful analysis

will be required to eliminate the effects of these bands and provide a reliable test of the DID model.

Properties of Pyroelectrics (in cooperation with A. Shaulov,

G. M. Loiacono, and W. A. Smith of Philips Laboratories): Interfacing

of the mi croprocessor system for control of the dynamic pyroelectric

response measurement system is now completed except for minor changes

which may be necessary during final de-bugging of the software. An

improved measurement technique designed to provide simultaneous determinations of the pyroelectric coefficient, dielectric constant, and

specific heat has been devised. Preliminary tests of the method using

analogue methods were only partially successful, but the approach still

appears promising since a fully digital system can be expected not to

suffer from problems of the type encountered in these tests.

Crystal-growth efforts at Philips Laboratories have not yet produced

samples of metal -hal ogen boracites suitable for dielectric or Raman

scattering measurements, but specific heat data have been obtained.

These results exhibit an effect which we noted previously in pyroelectric

coefficient and specific heat measurements in other ferroel ectri cs

,

i.e., rather than a single peak in the property of interest at the phase

transition temperature, we find multiple peaks within a small temperature

range in the immediate vicinity of the transition temperature. We have

found strong evidence linking this behavior to inhomogeneous internal

strain distributions in our samples, and demonstrated that the effect

can be controlled to great extent by deliberately introducing non- uniform strains or removing them by annealing. Review of existing data,

425
together with some new measurements, clearly showed that this behavior is

most pronounced in crystals which are strongly ferroel astic , either

because the phase transition is intrinsically ferroelastic or because the

primary order parameter is strongly coupled to an elastic distortion. A report of these findings has been accepted for publication in Ferroelectrics .

Nondestructive Evaluation

Subtask 9 of Task 12154

A. Feldman, A. H. Kahn, G. S. White

Theoretical Modeling in Eddy Current NDE : We have examined methods for

solving inversion problems by the analysis of eddy current experimental

data. If we limit the investigation to simple geometries, such as a slab or a cylinder, it should be possible to use impedance measurement

as a function of frequency to construct a resistivity profile of the

material by examination. This inversion can be performed by a method of

integral equations (known as the Gel fand-Levitan and Marchenko methods

in quantum theory) and by another method of direct Fourier analysis.

Both methods are now being explored for computational practicability.

In the problem of crack diagnosis by eddy current methods, there

have been reports of wide variability in the signals from real and

artificially produced crack or other defect specimens. Part of this

variability may arise from the zone of plastic deformation in the

vicinity of the crack. This plastic zone may vary in dimensions and in

material parameters, according to its method of production. Initial

calculations show that expected resistivity variations in the plastic

zone have little effect on eddy current signals, but that possible

variations in magnetic permeability, as in stainless steels, could

produce a significant effect. A computational approach, based on the

finite element method, is being prepared for finding the eddy current

distribution in the vicinity of a crack with allowance for the variation

of material parameters in the plastic zone.

Optical Nondestructive Evaluation : Optical scattering from defects

is an area of importance in nondestructive evaluation. It is the purpose

of our research to determine whether quantitative data, such as defect

dimensions, obtainable from optical scattering data. For this purpose

we have been performing both measurements and model calculations of

radiation scattered from well-defined shallow grooves in metallic

surfaces and have compared theory with experiment.

In the experiments, chopped 10.6 pm radiation from a 3 watt C0 2 “laser

was incident normal to a specimen containing a shallow rectangular groove.

The specimens were prepared by scribing of grooves into an aluminum coating

that had been evaporated onto glass optical flats. Two sets of specimens

were used: one set of specimens was used as scribed; in the other set,

the specimens were overcoated with an additional thin layer of aluminum.

The groove dimensions in both specimen sets were nominally 10, 20, and

50 pm wide by 0.5 pm deep. Figure 6 shows the measured profile of a 50 pm

uncoated groove.

426
Figure 6. Upper, middle and lower cross sections of uncoated 50 cm groove measured

by diamond stylus orofi 1 ometer

.

I

1

i

i

427
The use of 10.6 pm radiation has several advantages: the effect on scattering of surface microirregularities is minimized; the fabrication of

well-defined grooves of dimensions comparable to the wavelength is facilitated;

the far field approximation in the model calculations can be used.

A schematic diagram of the measurement apparatus is shown in figure 7. Scattered radiation was measured by a pyroelectric detector that was swung

about the specimen in a plane that contained the incident beam and that was perpendicular to the groove in the specimen surface. Careful attention was paid to system alignment because certain alignment errors were shown to cause severe distortion of expected scattering patterns.

Model calculations of the expected scattering were performed on the

basis of Fraunhofer diffraction theory. The following assumptions were

made: the incident beam had a Gaussian intensity distribution; the beam

width was significantly larger than the groove width; scattering was due

to specular reflection from the specimen surface and the groove bottom

but not from the groove walls. The resultant scattering function obtained

was the diffraction pattern of a uniformly illuminated slit with the

intensity uniformly modulated by a factor dependent on the depth of the

groove. Figure 8 shows a comparison between experimentally determined

scattering and an empirical fit to the data of a single slit diffraction

pattern. The points denote the measured scattering intensity of a nominal 50 pm wide uncoated groove as a function of scattering angle. The

solid curve is the diffraction pattern of a 52 pm wide slit. Agreement

appears to be quite good. Comparable results have been obtained with some

of the other grooves; however, with certain grooves, large discrepancies

were observed which are attributed to groove irregularities.

Further work is planned to compare scattering from deep grooves with

theory and also to study the effect of polarization on the scattering

function.

Energy States in Silicon

Subtask 10 of Task 12154

A. H. Kahn (in collaboration with J. R. Lowney and H. S. Bennett

of the Electron Devices Division)

In the design for fabrication and operation of semiconducting

devices, it is necessary to know the density of electronic states of the

bands and of the impurities. At high doping levels, screening effects

should cause a disappearance of the bound states, and this information

should be included in models for device operation and fabrication. To

provide this information, we have studied the disappearance of impurity

levels in silicon and germanium due to free-carrier screening of the

Coulomb field of the impurity ions. The ground state eigenfunctions and

eigenvalues have been calculated for electrons described by an ellipsoidal

effective-mass Hamiltonian. A two-dimensional finite element analysis

was used_to obtain the solutions. _0nly moderate carrier densities

( 1

0

1

9

cm 3 for silicon and 10 18 cm 3 for germanium) are needed to cause

the impurity levels to disappear into the conduction band, the result at

high doping densities being simply a degenerate semiconductor.

428
Target

Figure 7. Schematic diagram of scattering

apparatus

.
(sj|uf| AjBJijqjv) (Ajjsuejui) 6o"|

Figure 3. Logarithm of observed scattering (triangles) from uncoated

50 urn wide specimen superimposed on the calculated logarithm

of a Csolid) ideal single slit diffraction pattern from a 52 urn side slit.

430
In figure 9 we show a typical example of the silicon impurity wave

function as calculated by the finite element method. Because of the

anisotropic mass, cylindrical coordinates are used. For this case,

screening has reduced the binding energy to 11 percent of its unscreened

value. By extrapolation from similar computations, we obtained the

critical screening radius at which the bound level disappears.

SILICON DONOR MODULATION FUNCTION

SCREENING RADIUS = 50a

o< E = -2.37 * 10'4

R'

I F(p’. z

)

Figure 9. Display of the finite element wave' function F (p

1 ,

z

1 ) for a bound donor electron in silicon with screening radius r so= 50 a (a

Q = 0.529 x 10 8 cm). With this degree of screening, the

binding energy is reduced to 11 percent of the unscreened value.

El ectrocatalysi

s

Subtask 11 of Task 12154

M. I. Cohen

These efforts are directed at the need for measurement of the

electrochemical characteristics of materials. The primary effort is

toward the development of automated instrumentation for both laboratory

and field acquisition of data to be used for the determination of these

characteristics. This program is being funded by three other agencies

(DOT, EPRI, and DOE). Although each agency has a particular objective,

the three are complementary, enabling a single comprehensive design for

instrument construction.

The three programs consist of:

1. Federal Highway Administration - Measurement of Corrosion

of Reinforcing Bars in Concrete

2. Electric Power Research Institute - Corrosion of Concentric

Neutral Cable for Power Distribution

431
3. Department of Energy - Measurements of El ectrocatalytic

Characteristics of Fuel Cell Materials

All three programs are joint efforts of this Division with the

Chemical Stability and Corrosion Division (561), and they will be

discussed as a unit.

The instruments being developed are a direct outgrowth of the one designed previously for use with the ongoing program in electrocatalysis

for fuel cells. The design has been upgraded by going to a higher

performance processor (6809) which is compatible with the earlier

version (6800). This change enables an improvement in speed and flexibility

with minimal effects on the hardware and software already operating.

This original unit, as modified, is serving not only as an operating

device, but as a development system for the other systems being built.

Two are under constructi on , one a laboratory system and the other a field unit.

The field unit (being built for DOT) is a smaller version of the

lab system and is intended as a prototype for the Highway Administration.

If they deem the system effective, it will be adapted to weather extremes

and then duplicated and issued to various State highway departments.

The laboratory system is capable of operation identically the same

as the field unit, but can also perform other operations. Software is

interchangeable between the two versions. Since the hardware in each is

identical, new techniques can be tested on the lab system and when

perfected, transferred to the field unit.

The primary technique used at the moment in these instruments is a variation of that used in the original DOE instrument. The interfacing

to the measurement board is the same, but we are doing a gal vanostatic

determination instead of a potenti ostatic. In this technique, we measure

the potential difference between the working electrode and a reference

electrode due to a current impressed between the working electrode and

the counter electrode. By suitable timing choices, the corrosion potential

can be measured (when the polarizing current is off) at the appropriate

point on the waveform to eliminate the effects of the resistivity of the

surrounding electrolyte (concrete or soil depending upon which of the

other programs is involved).

The education program on microprocessors in instrumentation started

last year has continued. The Center for Materials Science funded another

session of the basic course in the fall of 1979. A third session is

being planned as is an advanced course.

The Advisory and Consultive services we have been providing are expanding. Many of the staff in the Center have taken advantage of

these services, and we expect further growth. An effort is underway to

organize our data files in a better fashion so that we can institute a more efficient electronic data library for Center use.

432
Plans

1) Delivery of field system to Federal Highway Administration at

the end of the Fiscal year (October 1).

2) Completion of extended laboratory system in first quarter.

3) Hardware implementation of other techniques and associated

programmi ng.

4) Impedance techniques for fuel cell measurements, and others,

will be developed.

5) Investigation of noise measurement techniques as a tool for

field determination of corrosion will be implemented.

433

DURABILITY OF CERAMICS AND GLASS IN SERVICE ENVIRONMENTS

Task 12155

The objective of this task is to develop test methodology and collect

critical data for the assessment of high temperature materials in MHD, coal

gasification and gas turbine environments. The Division's activities in

these areas are part of two programs that cover several Divisions of the

Center for Materials Science: Data Center for Fossil Energy Materials,

Materials for Coal Gasification, Structural Ceramics, and MHD Materials.

All four programs are supported by the Department of Energy augmented

by some NBS contributions. The work of each project is closely related

to and based on the expertise of Tasks 1-4.

Data Centers for Materials and Components for Fossil Energy

Appl i cations

Subtask 1 of Task 12155

H. M. Ondik, A. Perloff, W. S. Brower with R. C. Dobbyn, W. A. Willard,

I. J. Feinberg, (562)

The Fossil Energy Information System consists of two Data Centers

operating cooperati vely to provide a central data base of 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 MHD

power generation. This Center is largely staffed by personnel from the

Ceramics, Glass, and Solid State Science Division, Ondik, Brower and

Perloff with Feinberg (562). The major source of the data is the

Center's library of DOE materials research contractors' reports. There

are between 45 and 50 DOE-funded projects generating materials properties and performance data for coal conversion and utilization and MHD

powder generation. As time allows, other information sources are sought to expand the data base. Computer storage of the materials

properties data base and access to it will be controlled using a com- mercially available data base management system so that, in time, users may have direct on-line access to search the data.

The other segment of the information system is the Failure Information

Center largely staffed by members of the Fracture and Deformation Division,

Dobbyn and Willard with Brower (565). The source of 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. One goal of the

Center is to develop the file of operating experiences and correlate them

so that trends will be observed indicating primary causes of plant failures

for the guidance of designers and operators of coal conversion plants.

A major aim of the total information effort is to access all of the

data through one Data Base Management System (DBMS). The nature and

structure of the data sets of the two Centers are too different to

permit storage and search of the data in one file, but the same DBMS

435
can be utilized to control two data files so that they can be searched

consecutively using the same search terms. The user can then obtain the

results on a given material or performance characteristic provided both

by reseach and testing programs and by in-service experience. Procurement of the DBMS and a commercial computer vendor's services has occupied

a large portion of the staff efforts of the Materials Properties Data

Center. After completing the technical evaluation of the written proposals

submitted in response to our request for proposals, it was necessary to

prepare and keyboard some 80 data sets (5,000 lines of data) and transfer

these to magnetic tape for testing use of the competing vendors. A

series of technical explanations to the vendors were also necessary

because our data are much more complicated than the material with which

most commercial vendors deal. A double series of benchmark tests were performed by each vendor, testing their handling of the data and the

capabilities of their systems. A contract has been awarded and training

in the design and use of the DBMS for the personnel of the two Data

Centers is beginning.

The existing computer file of the Failure Information Data base

contains some 500 reported failures. Although fewer pilot plants are now operating, resulting in a very slow rate of increase of the data

file, there is continuing interest on the part of the user community.

Some 1100 reports and about 30 data tables and abstracts summarizing inservice materials and components performance were sent out in response

to over two dozen requests. An interpretive report, analyzing erosive

wear failures has been published as an NBS Internal Report. Information

is regularly supplied for the Failure Experiences feature of the DOE

Material s and Components Newsletter , published by Battel! e-Col umbus.

The major effort of the two Data Centers for the past year has been

the preparation of a publication, Construct!’ on Material s for Coal

Gasi f ication--Performance and Properties Data , currently submitted to

DOE for approval. This book contains information gained in practical

plant experience and also the results of materials research and 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 contruction. A separate

section of the Handbook includes extended data for the chemical, physical,

and mechanical properties of the candidate materials. The book will

consist of loose-leaf pages so that increasing and revising the data can

be done readily on a regular basis.

Chemical Degradation of Ceramics: Reactions and Transformations

Subtask 2 of Task 12155

F. A. Mauer, C. R. Robbins

The investigation of castable refractories for coal gasification

applications in support of flexural strength measurements (see Task

12122) has been completed. Both conventional and j_n si tu powder diffraction analysis methods were used to determine the chemical response

of test specimens to environments intended to simulate initial start up

436
and operation of a gasification reactor. Some results of an optical

microscopy, SEM, and powder diffraction analysis of approximately forty

core samples from the refractory lining of the Conoco Lignite Gasification Pilot Plant in Rapid City, SD, were also included in an attempt

to correlate short term Jjn si tu test data with the effects of much longer

exposure (3/4 year) under actual service conditions (0.9 MPa and 843 °C).

The following two paragraphs are from the summary of the final report

(NBSIR 80-2064).

"The i_n si tu x-ray studies have shown that, in the presence of

steam and with changes in temperature, a high purity castable refractory

is subjected to frequent changes in bonding phases and to intervals in

which the main bonding phase is in a- state of transition. These changes

are undesirable and should be minimized by avoiding exposure of the

refractories to steam below 750 °C, or preferably 900 °C. Reaction of

the high purity refractory with steam containing alkalis and silica from

impurities in the coal should be expected to occur at the working face

with formation of various silicates. These may alter the course of

hydrati on/dehydration reactions and the formation of bonding phases.

"The CaO-Al 2 03 -Si 0 2 refractory has been shown (Task 12122) to

increase markedly in flexural strength with exposure to either simulated

or pilot plant gasification atmospheres. The increase in strength is

attributed to the formation of CAS 2 and A3

S 2

. Once formed, these

compounds are not subject to hydration/dehydration and are stable in

steam over a large temperature range. Leaching of silica and other

components from this type of refractory has been observed, but may not

pose a serious problem during the service life of the material."

Slag Viscosity

Subtask 3 of Task 12155

W. S. Brower, J. L. Waring

Viscosity measurements have been made on two synthetic slag com- positions over a range of elevated temperatures at steam pressures up

to ~ 100 psi. The compositions of the two synthetic slags were quite

different in respect to their alkali content, one was high, ~ 20 wt %,

the other much lower ^ 5 wt %. These slags were modeled to represent

a high alkali western coal residue and lower alkali eastern coal residue.

The high alkali composition exhibited an increase in viscosity with

increasing steam pressure, whereas the lower alkali composition exhibited

a decrease in viscosity with increasing steam pressure. The viscosity

behavior of the high alkali slag was unexpected, the low alkali slag

behaved in manner more consistent with conventional glass technology.

A summary report has been prepared and submitted for publication.
High-Temperature Applications of Structural Ceramics: Kinetics

of Oxidation

Subtask 4 of Task 12155

F. A. Mauer, C. R. Robbins, T. A. Hahn

Under an interagency agreement with the Department of Energy signed

in January 1980 research is being conducted by NBS under four projects

(see Task 12122). A principal factor affecting the mechanical performance

of silicon carbide, silicon nitride, sialon, and other structural

ceramics in high temperature applications is their ability to remain

stable in atmospheres having a wide range of oxygen partial pressures.

The objective of this subtask is to identify the crystalline phases

formed under well-defined oxidation conditions in the interior and in

the surface of various structural ceramics and to determine the factors

that effect oxidation kinetics. The information will be used in

explaining the degradation of mechanical properties at elevated temperatures. The method involves x-ray analysis of specimens before and

after high temperature fracture tests and crack growth tests (Task

12122), as well as specimens exposed in a laboratory furnace in con- trolled atmospheres. To date, the pre-test analysis of a set of nine

sialon specimens of compositions represented by Si 6 -^ Al^ 0^ N 8 -^ (where Z = 1, 1.3, 2.3, and 3) has been completed. The samples which

will be used for fracture and crack growth tests were prepared by

Kazuo Kobayashi of the National Industrial Research Institute of Kyushu,

Japan. Another group of twenty-three specimens prepared in the Laboratory

of Professor Tien at the University of Michigan is now being analyzed.

These specimens, which will be used in notched bend fracture tests, have

a refractory garnet grain boundary phase intended to reduce the high

temperature creep characteristic of materials with a glassy intergranual

phase.

Thermochemical Data for Structural Ceramics

Subtask 5 of Task 12155

J. L. Waring, R. S. Roth, H. S. Parker (M. C. Austin)

This project is part of a Center-wide program funded by DOE on structural ceramics ( S

i

3 N 4 , SiC) for gas-turbines. The purpose of this work

is to improve the understanding of the mechanical behavior of structural

ceramics and to provide essential data on refractory materials used in

fossil energy systems. As part of the program, a study (ongoing for about

six months) is being conducted to determine the relationship between

thermodynamic, thermochemical properties, microstructure, and mechanical

properties of silicon nitride and silicon carbide based materials. In

addition studies are being conducted to improve the properties of these

materials by controlling compound formation, melting, decomposition, and

phase changes during use.

In the past the work of this group has been concerned primarily

with oxygen-based systems. The increasing emphasis on nitrogen-based

ceramics has necessitated considerable modification of existing equipment

438
and installation of new equipment to provide heating and characterization

of specimens under controlled conditions of atmosphere, temperature, and

pressure. Equipment now in use can provide for heating of bulk samples

at temperatures as high as 2400 °C, pressures to 300 psi , and partial

pressures of oxygen as low as 10 24 atmosphere. Characterization by

high temperature x-ray, in controlled atmosphere, to temperatures in excess of 1600 °C is also possible.

The thermodynamics of the so-called a <-»• |3 transition in Si 3 N 4 was investigated in the high temperature x-ray furnace. The hexagonal c-axis

of p - S

i

3 N 4 varied from about 2.911 A at room temperature to about 2.924 A

at 1410 C and the a-axis varied from about 7.616 A at room temperature to

7.644 A at 1410 C. The dissociation temperature of Si 3 N 4 in small sealed

Mo tubes appears to occur between 1925 °C and 1950 °C. This is the

temperature at which the dissociation of Si 3 N 4 into N 2 gas and Si liquid

has become so rapid that the experiments can no longer be continued in a sealed tube for a practical length of time.

The formation of the x 4 phase along the join Si 3 N4 : 2S i

0

2

: 3A1 2 0 3

(mullite) has been reported to cause the loss of mechanical strength

in structural Si 3 N 4 bodies. X-ray diffraction patterns of all the

specimens prepared showed primarily x x with a trace of mullite and

(a and p)-Si 3 N 4

. Single phase x 4 was not obtained and more work is

needed to properly characterize the x 4 phase.

Several attempts were made to grow single crystals of the p-Si 3 N 4

phase in a horizontal resistance furnace. High purity (99.99 percent)

silicon was heated in purified argon atmosphere to ^ 1450 °C. At this

point, forming gas (95 percent N 2 /5 percent H 2 ) was admitted to the growth

chamber with a 10:1 mass flow ratio A/N, maintained for 24 hours and cooled

in pure argon. Many small prismatic crystals of p - S

i

3 N 4 (up to 0.5 mm

in length) had formed on the surface of the silicon with some glass and

SiC crystals. Further experiments to eliminate glass and carbide formation

are in progress.

Thermochemistry of Slag

Subtask 6 of Task 12155

L. P. Cook

Phase equilibrium investigations into the high temperature behavior

of potassium-bearing coal slag, similar to that which is found in MHO

systems, were resumed. This work has been directed along two lines:

(1) determination of the major chemical distinctions between seven- component slags produced by combustion of "eastern" and "western" coals;

and (2) a more in-depth study of the phase equilibrium properties of the

potassium-rich part of the system K 2 0-Ca0-Al 2 0 3 -Si0 2

.

A paper presented at the 7th international MHD conference held

June 1980 at MIT described the first series of results of multicomponent modeling of synthetic K2 0-bearing slags. Relatively small

differences in bulk chemistry (particularly CaQ/FeO ) were shown to

439
have dramatic effects on the phase equilibrium behavior of such slags.

Oxidation effects were shown to be particularly important from a theoretical point of view, especially in determining type and degree

of melt polymerization. Further research in the seven component

K2 0-Ca0-Mg0-Fe0 -Al 2 0 3 -Si02 system will focus on determining the nature

(P-T-X properties) of the high temperature two-liquid field observed

in the "eastern" slag. An attempt will be made to develop solution

models —probably based on melt polymerization theory—which adequately

describe this behavior. Separation of an iron-rich liquid in such

slags under MHD conditions could conceivably affect generator performance.

Phase equilibria in the sytem K2 0-Ca0-Al 2 0 3 -Si0 2 , a simplified model

system for "western" MHD slags, have proved to be more complex than thought

Research in this system has brought to light features of potential significance for K2 C0 3 seed recovery, in particular: (1) The difficulty with

which C0 2 is removed from K2 Si0 3 and KA10 2 -rich compositions, and (2) the

tendency for anomalous melting in the subsystem K2 C0 3 -KA102

. Experimental

results suggest that a substantial amount of K2 C0 3 may be held dissolved

in slag solutions rather than forming a well-defined, readily separable

carbonate phase. In the system K2 C0 3 -KA10 2 , compositions with a high

percentage of K2 C0 3 may be held for 400 °C above the fusion temperature of

K2 C0 3 and yet show no sign of melting. Such potassium carbonate/al umi nate

mixtures are thought possibly to form partially ordered liquids (mesomorphi

phases), thus leading to unusually high viscosity resembling that of a solid. A paper describing these results was presented at the Conference

on Ceramic Interfaces held at Berkeley in July 1980. Other experiments

in K2 0-Ca0-Al 2 0 3 -Si02 have pointed to the existence of what may be new quaternary phases. These experiments have also reaffirmed the relatively

high stability of the Ca0-KA10 2 -Si0 2 subsystem, a major chemical divide

within the quaternary system, on opposite sides of which lie melts

with markedly different properties. As these phase equilibrium studies

progress, correlation with the potassium vapor pressure measurements

completed in Division 561 is done through a collaborative effort at

modeling liquid/solid/vapor equilibrium relations. New data have so far

reaffirmed the tendency for additions of CaO to reduce the activity of

K2 0 to a degree well beyond the proportions involved.

Electrical Conductivity and Polarization Effects in Coal Slag

Subtask 7 of Task 12155

W. R. Hosier

The most abundant material likely to be found in the duct wall of an MHD generator is coal slag and this must pass all the generated current in

the transverse direction. The electrical conductivity of this complex

substance is not well understood. While electrode and insulator materials

have been studied also, the main emphasis is to obtain a thorough understanding of the slag conductivity process. These studies include the

relationships of the charge transport mechanism to temperature, oxygen

partial pressure, slag elemental components and chemistry, and previous

treatment with respect to temperature. All these conditions are inter440
related and affect the conductivity. Because the physical properties

of slag are unusual, special measurement techniques must be developed to

insure adequate control over the measurement conditions.

A four probe dc measurement technique has been developed which

eliminates or minimizes many of the difficulties usually encountered

in slag conductivity measurements. The slag is held in a cylindrical

crucible made of dense aluminum oxide. The electrodes are attached

by a special process after the crucible is filled with the slag specimen

to be studied. This approach eliminates the errors which usually ensue

when an open boat is used, i.e., (a) slag surface oxidation or reduction

effects, and (b) sample size and shape variation during the course of

the measurement, particularly when going through a liquid-solid transition.

Careful measurements as a function of temperature and oxygen pressure

are taken of voltages between all probe sets. Extensive measurements have

been made on an Eastern slag from a Bow, NewHampshi re , steam generating plant.

This slag is typical of a high iron content slag where the conductivity

originally was thought to be due in large part to a semi-conductive exchange

of electrons between Fe

+2 and Fe+3 ions in the slag. Present measurements

indicate that at high temperatures (above 1385 °C) the conductivity is

due primarily to the movement of iron ions while at low temperatures

(below 1000 °C) the conductivity is probably due to a crystalline bridging

in a noncrystalline matrix. The amount of crystalline material depends

on the slag composition as well as the temperature and time from which

it was cooled from the liquid to solid state. The conductivity above

1385 °C depends on the iron and not the potassium content or on the

ambient oxygen pressure. Furthermore, at high temperatures the conductivity appears to be governed by the Walden Rule, i.e., cr-q = constant

where a is the conductivity and q is the viscosity since the conductivity

more than doubles when the iron content is doubled. Iron additions

lower the viscosity of the melt.

441
* i
Other Activities of the

Ceramics, Glass, and Solid State Science Division

Invited Talks

Thermodynamics of Selected (K2 0, CaO)-rich Aluminosilicate Melts

82nd Annual Meeting of the American Ceramic Society,

Chicago, Illinois

L. P. Cook

April 30, 1980

Quasichemical Melt Polymerization Model of Seed/Slag Interaction

7th International Conference on Electrical Power Generation,

MIT, Cambridge, Massachusetts

L. P. Cook

June 16, 1980

Interfacial ly Controlled Phenomena in the System K2 C0 3 -KA10 2 Proceedings on Surfaces and Interfaces in Ceramic and CeramicMetal Systems, Berkeley, California

L. P. Cook

July 29, 1980

High Temperature Melting Point Determinations at High Pressure

Department of the Army, Ballistic Missile Defense, Advanced

Technology Center, Huntsville, Alabama

G. J. Piermarini

October 1979

Analysis of Thermally Generated Microstresses in Polycrystalline

Beryllium Due to Beryllium Oxide Inclusions, 7th Inti. Symposium

on Thermal Expansion, ITT Research Institute, Chicago, Illinois

T. A. Hahn and R. W. Armstrong

November 1979

AB 4 Compounds

Gordon Research Conference

Santa Barbara, California

S. Block

January 1980

X-ray Diffraction of Single Crystals Under High Pressure

Crystallography at High Pressures (Workshop), Max Planck

Institute for Solid State Research, Stuttgart, West Germany

G. J. Piermarini

May 1980

X-ray Diffraction of Polycrystall i ne Materials Under High Pressure

Crystallography at High Pressures (Workshop), Max Planck Institute

for Solid State Research, Stuttgart, West Germany

G. J. Piermarini

May 1980

443
Low Temperature Studies with the Diamond Anvil Pressure Cell

Gordon Research Conference

Meriden, New Hampshire

R. G. Munro

June 1980

Computer Evaluation of Crystallographic Data

Denver X-ray Conference, Denver, Colorado

C. R. Hubbard , J. K. Stalick, and A. D. Mighell

August 1980

Computer Evaluation of Crystallographic Data

American Crystal lographic Association Summer Meeting

University of Calgary, Calgary, Alberta, Canada

J. K. Stalick , A. D. Mighell, and C. R. Hubbard

August 1980

Restricted Diffusion of Biopolymer Molecules in Right Porous Matrices

Columbia University, New York, New York

W. K. Haller

November 28, 1979

Preparation and Properties of FI uorophosphate Glasses

Glass Through Chemical Processing, Rutgers University

New Brunswick, New Jersey

J. T. Wenzel, D. H. Blackburn, and W. K. Haller

March 20, 1980

Amorphous Thin Films by Codeposition

Glass Division Meeting, American Ceramic Society

Chicago, Illinois

D. M. Sanders, E. N. Farabaugh, and W. K. Haller

April 30, 1980

Sodium and Boron Vaporization from a Borosilicate Glass Melt

Glass Division Meeting, American Ceramic Society

Chicago, Illinois

J. T. Wenzel and D. M. Sanders

April 30, 1980

The Photoelastic Effect in Optical Materials

Topical Conference on Basic Optical Properties of Materials

National Bureau of Standards, Washington, D.C.

A. Feldman

May 7, 1980

Approaches to Eddy Current Inversion Problems

Workshop on Eddy Current NDE

General Electric Co., Schenectady, New York

A. H. Kahn

February 12, 1980

444
Technical and Professional Committee Participation and Leadership

American Ceramic Society

Committee on Publications of the American Ceramic Society

Subcommittee on "Phase Diagrams for Ceramists"

R. S. Roth, Chairman

American Society for Testing and Materials

C-8: Refractories

W. S. Brower, Member

C- 2 1 : Ceramic Whitewares and Related Products

H. S. Parker, Member

C. R. Robbins

Member: E- 38 : Resource Recovery

C-38.06.03 Fly Ash in Construction Materials

C-9: Concrete and Concrete Aggregates

C-18: Natural Building Stones

C18.0304: Sandstone

JCPDS-International Centre for Diffraction Data

C. R. Hubbard

Member: Technical Committee

Education Subcommittee

Computer Subcommittee

NBS Research Associate Advisory Subcommittee

Data Base (AIDS) Task Group

Chemical Informtion System Task Group

International Commission on Glass

W. K. Haller, U.S. Representative

International Commission on Glass

Subcommittee VIII, Standard Reference Glasses

W. K. Haller, Vice Chairman

International Commission on Glass

Subcommittee A, II-Durability and Analysis

W. K. Haller, Member

American Society for Testing and Materials

C-14 on Glass and Glass Products

M. J. Cellarosi, Vice Chairman

W. K. Haller, Member

D. J. Cronin, Member

C14.01: Nomenclature of Glass and Glass Products

M. J. Cellarosi, Chairman

C14.03: Chemical Properties of Glass

W. K. Haller, Member

445
C14.04: Physical and Mechanical Properties of Glas

M. J. Cellarosi, Member

D. J. Cronin, Member

C14. 08: Flat Glass

M. J. Cellarosi, Member

American Society for Testing and Materials

M. J. Cellarosi

Member: E-38 Resource Recovery

E-44 Solar Heating and Cooling

American National Standards Institute

M. J. Cellarosi

Member: F-l Hybrid Electronics

D. J. Cronin

Member: Z- 26 . 1 Safety Glazing of Motor Vehicles

Z-97 Architectural Safety Glazing

Joint Electron Devices Engineering Councils

M. J. Cellarosi, Member

Electronic Industries Association

Committee on X-ray and Implosion TV Standards

M. J. Cellarosi, Member

Steering Committee, Greater Washington Solid State Physics

Col 1 oqui urn M. I. Bell

Member 1979-1980, Treasurer 1980-1981

ASTM Committee FI, Subcommittee 2 on Lasers

A. Feldman, Editor

Advisory Board of the CRC Handbook Series in Laser Science

and Technology

A. Feldman, Member

Review Panel for DOE MHD Contract at Montana State University

Bozeman, Montana, November 1979

W. R. Hosier, Member

Basic Microprocessor Course

M. I. Cohen (taught another session, Center-funded,

Fall 1979)

446
Publ i cations

Neutron Powder Diffraction Study of Ta2 W0 8 A. Santoro, R. S. Roth, and 0. B. Minor

Acta Cryst. , B35, 1202 (1979)

Magnetic Properties and Hyperfine Interactions in the b" 1 Phase

of Potassium Ferrite

V. P. Romanov, G. A. Candela, R. S. Roth, and L. J. Swartzendruber

J. Appl . Phys., 50 [10] 6455 (1979)

Structure of (3- Chi oro-2-hydroxy-5~ni trophenyl )-(2 ' -chi orophenyl

)

iodonium Hydroxide Inner Salt

S. W. Page, E. P. Mazzola, A. D. Mighell, V. L. Himes, and

C. R. Hubbard

J. Am. Chem. Soc. , J_0]_ , (1979)

The Synthesis and Crystal and Molecular Structure of

((C 7 H 7 ) 3

P 4 Cu 4 W2 S 4 ), a Dimer, of Bis((tri-p-tolylphosphine)copper)

oxotri thi otungsten

R. M. Doherty, C. R. Hubbard, A. D. Mighell, A. R. Siedle, and

J. M. Stewart

Inorg. Chem. J8, 2991 (1979)

ADOBE II: Factors Affecting the Durability of Adobe Structures

P. W. Brown, C. R. Robbins, and J. R. Clifton

Studies in Conservation 24, 23 (1979)

Influence of Pq on Vaporization of Odium Disilicate at 1345 °C

D. M. Sanders and W. K. Haller

J. Amer. Ceram. Soc. , 62 424 (1979)

Survey of Refractive Data on Materials for High Power Ultraviolet

Laser Applications

A. Feldman, R. M. Waxier, and I. H. Malitson

SPIE Proc. , Vol. 204, Physical Properties of Optical Materials,

pp. 95 (1979)

Properties of Crystalline Materials for Optics

A. Feldman and R. M. Waxier

SPIE Proc., Vol. 204, Physical Properties of Optical Materials,

pp. 68 (1979)

Eddy Currents in a Conducting Cylinder with a Crack

R. Spal and A. H. Kahn

J. Appl. Phys. , 50, 6135 (1979)

MHD Materials

S. J. Schneider, T. Negas, and H. P. R. Frederikse

Rev. Int. des Hautes Temp. Refract. , Fr. 1_6, 169 (1979)

447
Interfaci al ly Controlled Phenomena in the System K2 C0 3 -KA102

L. P. Cook

Proceedings on Surfaces and Interfaces in Ceramic and CeramicMetal Systems, Berkeley, California (July 1980)

A Preliminary Industrial Evaluation of the Fluidic Capillary

Pyrometer

R. M. Phillippi and T. Negas

Proceedings of ASME 20th Annual Conference on Fluidics, Chicago,

Illinois

(November 1980)

Fluidic Capillar Temperature Sensors: Materials, Design, and

Fabrication

T. Negas, H. S. Parker, W. S. Brower, R. M. Phillippi,

T. M. Drzewiecki, and L. P. Domingues

Proceedings of ASME 20th Annual Conference on Fluidics, Chicago,

II 1 i noi

s

(November 1980)

Phase Equilibria Research in Portions of the System K2 0-Mg0-Fe2 0 3

- A1 2 0 3 Si

0

2 R. S. Roth

Advances in Chemistry Series #186, Solid State Chemistry: A

Contemporary Overview (November 1980)

Platinum Thiotungsten Compounds. Crystal and Molecular Structure

of Bis(Triethylphosphine)platinum Tetrathiotungsten

A. R. Siedle, C. R. Hubbard, A. D. Mighell, R. M. Doherty, and

J. M. Stewart

Inorg. Chem. Acta 38, 197 (1980)

New Bond-Delocalized Dianions: The Crystal Structure of 1 : 3- B i

s

(dicyanomethyl ene) Cronconate Salt

V. L. Himes, A. D. Mighell, C. R. Hubbard, and A. J. Fatiadi

J. Res. NBS, 85, No. 2, March-April 1980

Synthesis and Antitumor Activity of Cyclophosphamide Analogs.

3. Preparation, Molecular Structure Determination, and Anticancer

Screening of Racemir ci

s

- and trans - Phenyl cyclophosphamide

V. L. Boyd, G. Zon, V. L. Himes, J. K. Stalick, A. D. Mighell,

and H. V. Secto

J. Med. Chem. 23, 372 (1980)

Diaxanthyl urea ( N ,

N

1 -di-9H-Xanthen-9-yl urea)

C. R. Hubbard, A. D. Mighell, and A. J. Fatiadi

J. Res. NBS, 85, No. 3, May-June 1980

Lattice Symmetry Determination

A. D. Mighell and J. R. Rodgers

Acta Cryst. A36, 321 (1980)

448
The Reliability of Powder Indexing Procedures

A. D. Mighell and J. K. Stalick

Proc. of Accuracy in Powder Diffraction, NBS Spec. Pub. 567

February 1980

Standards for the Publication of Powder Patterns: The American

Crystallographic Associations Subcommittee Final Report

L. D. Calvert, J. L. FI ippen-Anderson, C. R. Hubbard, Q. C. Johnson,

P. G. Lenhert, M. C. Nichols, W. Parrish, D. K. Smith, R. L. Snyder,

and R. A. Young

Proc. Accuracy in Powder Diffraction, NBS Spec. Pub. 567

February 1980

Standard Reference Materials for Quantitative Analysis and

d-spacing Measurement

C. R. Hubbard

Proc. Accuracy in Powder Diffraction Symposium, NBS Spec. Pub. 567

February 1980

Radial Distribution Studies Under Highly Constrained Conditions

R. G. Munro

J. Res. NBS 85, 99 (1980)

Les Hautes Pressions

R. G. Munro, S. Block, and G. J. Piermarini

La Recherche 113 , 806 (1980)

Analysis of Thermally Generated Microstresses in Polycrystalline

Be Due to the Presence of BeO Inclusions

T. A. Hahn

Proc. Thermal Expansion Symposium, 1980

Materials Science and Technology for More Efficient Manufacturing

James Mattie, Charles H. Berg, and Mario Cellarosi

in "Materials Aspects of World Energy Needs," pp. 151-154

National Research Council, National Academy of Sciences, 1980

Dielectric, Pyroelectric, and Thermal Properties of Li NH 4 S0 4 and

Li ND 4 S0 4 G. M. Loiacono, M. Delfino, W. A. Smith, M. I. Bell, A. Shaulov,

and Y. H. Tsuo

Ferroelectrics 23, 89 (1980)

Thermal and Dielectric Properties of LiKS0 4 and LiCsS 4 M. Delfino, G. M. Loiacono, W. A. Smith, A. Shaulov, Y.H. Tsuo,

and M. I. Bell

J. Solid State Chem. 3J_ , 131 (1980)

Improper Ferroel ectrics for Pyroelectric Detection of Infrared Radiation

A. Shaulov, W. A. Smith, G. A. Loiacono, M. I. Bell, and Y. H. Tsuo

Ferroel ectrics , 27, 117 (1980)

449
Electroreflectance of PZT Ceramics

S. H. Shin, F. H. Poliak, and M. I. Bell

Ferroel ectrics , 27, 147 (1980)

Strain-Induced Splitting and Oscillator Strength Anisotropy in

Calcium Fluoride, Strontium Fluoride, and Barium Fluoride

A. Feldman and R. M. Waxier

Phys. Rev. Lett. , 45, 126 (1980)

The Photoelastic Effect in Optical Materials

A. Feldman and R. M. Waxier

Basi c Qpti cal Properti es of Materi al s Summari es of Papers , ed.

A. Feldman, NBS Spec. Pub. 574 (USGPO, Washington: 1980), pp. 204

Radiation Damage in MgAl 2 0 4 G. P. Summers, G. S. White, K. H. Lee, and J. H. Crawford, Jr.

Phys. Rev. B 21_, #6, pp. 21, March 1980

Thermally Stimulated Conductivity in q-Irradiated MgAl 2 0 4 Crystals

G. S. White, K. H. Lee, and J. H. Crawford, Jr.

Semiconductors and Insulators, 5, 123 (1980)

Electrical Conductivity Mechanisms in Iron Containing Slags

W. R. Hosier, G. S. White, and T. Negas

7th Int. Conf. on MHD Electrical Powder Generation

Cambridge, Massachusetts (June 1980)

Quasichemical Melt Polymerization Model of Seed/Slag Interaction

L. P. Cook

7th Int. Conf. on MHD Electrical Power Generation

Cambridge, Massachusetts (June 1980)

Materials for Open Cycle MHD Generators

S. J. Schneider, H. P. R. Frederikse, T. Negas, and G. Rudins

in Current Topics in Materials Science , Vol. 4, North Holland

Publ i shi ng Co. , 1 980

Neutron Powder Diffraction Study of the Structures of CeTa0 4 , CeNb0 4 , and NdTa0 4 A. Santoro, M. Marezio, R. S. Roth, and D. B. Minor

J. Solid State Chemistry (in press)

Thermal Stability of Long-range Order in Oxides

R. S. Roth

Progress in Solid State Chemistry (in press)

The Structure of LaTa0 4 at 300 °C by Neutron Powder Profile Analysis

R. J. Cava and R. S. Roth

J. Solid State Chemistry (in press)

450
Ternary Compounds in the Ba0-Nd2 0 3 Ti02 System

D. Kolar, S. Gaberscek, B. Volavsek, H. S. Parker, and R. S. Roth

J. Solid State Chemistry (submitted)

(3-Chloro-2-oxo-5-nitrophenyl )(2~chlorophenyl ) Iodonium, Inner Salt

C. R. Hubbard, V. L. Himes, A. D. Mighell, and S. W. Page

Acta Cryst. (in press)

Registration/Identification of Crystalline Materials Based

on Lattice and Empirical Formula

J. R. Rodgers and A. D. Mighell

J. Chem. Inf. Comp. Sci. (in press)

Determination of the Relationship Between Derivation Lattices

A. Santoro, A. D. Mighell, and J. R. Rodgers

Acta Cryst. (in press)

High Pressure Crystallography (invited paper)

S. Block and G. J. Piermarini

in "History of Crystallography" (submitted to WERB July 1980)

to be published by Am. Cryst. Assn.

Viscosity and Glass Transitions in Liquids at High Pressures

(invited paper)

R. G. Munro, G. J. Piermarini, and S. Block

(submitted to WERB)(to be published in J. Phys. Chem. Japan)

Vaporization in an Unstirred Soda-Lime-Silica Glass Melt

S. Murai , J. T. Wenzel, and D. M. Sanders

Phys. Chem. Glasses (accepted)

The Effect of Striae on the Strength of Glass

W. Capps, H. Schaeffer, and D. J. Cronin

J. Amer. Ceram. Soc. (accepted)

The Role of Water Vapor and Sulfur Compounds on Sodium Vaporization

During Glass Melting

D. M. Sanders, M. E. Wilke, S. A. Hurwitz, and W. K. Haller

J. Amer. Ceram. Soc. (submitted)

A Standard Technique for Measuring Window Absorption and Other

Efficiency Losses in Semiconductor Energy Dispersive X-ray

Spectrometry

R. E. Stone, F. J. Walter, D. H. Blackburn, P. Pella and H. Kraner

J. X-ray Spectrometry (submitted)

Vi scosi ty-Temperature Relationships at One Atmosphere in the

System Diopside-Anorthi te

C. M. Scarfe, D. J. Cronin, J. T. Wenzel, and D. A. Kauffman

1979-1980 Yearbook of the Carnegie Institute, Washington, DC

(submitted to WERB)

451
Effects of Inhomogeneous Strain in Ferroel ectric Crystals Near

Their Phase Transitions

G. M. Loiacono, M. Delfino, A. Shaulov, W. A. Smith, and M. I. Bell

Ferroelectrics (to be published)

Complications in the Use of Raman Spectroscopy to Diagnose Annealing

of Boron-Implanted Silicon

R. A. Forman, M. I. Bell, and D. R. Myers

J. Appl. Phys. (to be submitted)

Effects of Stress on the Raman-Active Modes in Semiconductors

M. I. Bell

Proc. Vllth Int. Conf. on Raman Spectroscopy (to be published)

Electro-oxidation of Hydrogen in Mo-W Carbide Alloy Catalysts in

Acid Electrolyte

A. J. McAlister and M. I. Cohen

El ectrochimica Acta (submitted)

A Boundary Integral Equation Method for Calculating the Eddy

Current Distribution in a Long Cylindrical Bar with a Crack

A. H. Kahn and R. Spal

Proc. Symposium on Eddy Current Characterization

(accepted for publication by ASTM)

Disappearance of Impurity Levels in Silicon and Germanium Due

to Screening

J. R. Lowney, A. H. Kahn, J. L. Lue, and C. L. Wilson

J. Appl. Phys. (submitted)

The National Bureau of Standards Optical Measurement Program

Refractive Index, Thermo-optic Constants and Photoelastic Constants

A. Feldman, M. J. Dodge, D. Horowitz, and R. M. Waxier

Tenth Anniversary Volume, Laser Damage Symposia (accepted)

Temperature Dependence in Air of Fe

2+ Concentration in a Natural

Eastern Coal Slag

G. S. White, W. R. Hosier, and T. J. Castellano

J. Am. Ceram. Soc. (submitted)

Chemical Degradation of Castable Refractories in Coal Gasification

Process Environments

C. R. Robbins and F. A. Mauer

J. Materials for Energy Systems (in press)

Strength, Erosion, and Phase Equilibrium of Refractory Concretes

in Coal Gasification Environments

S. M. Wiederhorn, E. R. Fuller, Jr., and C. R. Robbins

in Properties and Performance of Materials in Coal Gasification

Envi ronment , ASM (in press)

452
Lead Alkali Apatites Without Hexad Anion: The Crystal Structure

of Pb 8 K2 (P0 4 )6

M. Mathew, W. E. Brown, M. A. Austin, and T. Negas

J. Solid State Chemistry (in press)

Piezo-optic Coefficients of Four Neodymium-aoped Laser Glasses

R. M. Waxier and A. Feldman

Appl. Opt. (accepted)

Division Seminars

Dr. Joseph Shamir, Israel Institute of Technology

"Determination of the Optical Constants of a Thin Film"

September 21, 1979

Professor Joel Bernstein, Ben-Gurion University

"Influence of Crystal Forces on Molecular Conformation"

October 18, 1979

Professor Philip Coppens, SUNY, Buffalo

"Experimental Charge Densities in Inorganic Materials"

November 13, 1979

Dr. Tom Soules, General Electric Company

"A Molecular Dynamics Calculation of the Structure of Sodium Silicate

G1 asses"

January 8, 1980

Dr. Sally H. Hunter, Florida International University

"EXAFS Structural Studies of Compound Amorphous Demi conductors"

February 1, 1980

Dr. Ulrich Strom, Naval Research Laboratory

"Spectroscopy of Tunneling Modes in {3-Alumina Fast Ion Conductors"

February 5, 1980

*Dr. Joe Wong, G.E. Corporate Research and Development

"EXAFS Studies of Glassy Solids"

March 4, 1980

Dr. Marcel Pulain, Universite de Rennes

"Zirconium Fluoride Glasses"

March 24, 1980

Dr. Albert Wright, Institut Lane-Lanievi n , France

"Observations of Nucleation in Glass-Ceramics bv SANS"

May 16, 1980

*Joint with Center for Materials Science

453
Dr. R. S. Roth, CMS (NBS)

"Use of High Resolution Electron Microscopy in Ceramic Research"

June 11 , 1980

Professor Robert Snyder, Alfred University

"Rebirth of X-ray Powder Diffraction"

August 1 , 1980

External Recognition

IR 100 Award for development of low non-linear refractive index

laser glass

September 1979

Books

Phase Diagrams for Ceramists

Edited by L. P. Cook, R. S. Roth, T. Negas , and G. W. Cleek

Published by the American Ceramic Society, Columbus, Ohio

Volume 4 (in press)

Accuracy in Powder Diffraction. Proceedings of Accuracy in Powder

Diffraction Symposium, June 1979

S. Block and C. R. Hubbard, eds.

NBS Special Publication 567 , 571 pp. , February 1980

PDF Workbook: Use of X-ray Powder Diffraction File

C. R. Hubbard, G. McCarthy, and C. Foris

(To be published by the JCPDS--International Centre for Diffraction

Data)(in press)

Basic Optical Properties on Materials —Summaries of Papers, May 1980

A. Feldman, ed.

NBS Special Publication 574 , 241 pp. , 1980

Special Reports

Slag Characterization: Viscosity of Synthetic Coal Slag in Stem

W. S. Brower, J. L. Waring, and D. H. Blackburn

NBSIR Report, prepared for DOE, June 1980

A High Temperature Transpi ration Apparatus for the Study of the

Atmosphere Above Viscous, Incongruently Vaporizing Melts

D. M. Sanders and W. K. Haller

Proceedings of the Tenth Materials Research Symposium on Characterization of High Temperature Vapors and Gases

National Bureau of Standards, Gaithersburg, Maryland, September 18-22,

1978

NBS Special Publication 561, Vols. I and II (1979)

454
AUTO, A Real Time Diffractometer Control System for the Interdata

7/16 Computer

R. L. Snyder, C. R. Hubbard, and N. C. Panagiotopoul os

Chemical Degradation of Castable Refractories in Coal Gasification

Process Environments

C. R. Robbins and F. A. Mauer

NBSIR 80-2064, Final Report to the U.S. Department of Energy, May 1980

Measuring the Rate of Corrosion of Reinforcing Steel in Concrete

E. Escalante, S. Ito, and M. I. Cohen

NBSIR 80-2012, For the Federal Highway Administration, March 1980

"User Evaluation of Crystal Data Products and Services: Questionnaire

Analysis and Impact"

NBS Tech. Note 1112, June 1980

J. K. Stalick, A. D. Mighell, and R. J. Boreni

Materials for Fuel Cells

L. H. Bennett, M. I. Cohen, A. L. Dragoo, A. D. Franklin, and

A. J. McAlister

NBS number not assigned, for DOE period covered January-December 1979,

in press

Quarterly Reports to DOE of NBS Contract work on Conductivity

Mechanisms in Coal Slag

W. R. Hosier

Standard Reference Materials

SRM 733 Certi fied--Gradient Furnace Liquidus Standard

Patents

Hybrid Temperature-Oxygen Fugacity Sensor

T. Negas, L. P. Domingues, T. Drzewiecki, and R. M. Phillippi

March 1979 (pending)

Sponsored Conferences

NML Topical Conference on Basic Optical Properties for Materials

NBS/0SA, Gai thersburg , Maryland, May 5-7, 1980

A. Feldman, Chairman, Organizing and Program Committee
‘

1
' p

I

.

1

REACTOR

RADIATION

DIVISION

REACTOR RADIATION DIVISION (566)

Robert S. Carter, Chief

Tawfik M. Raby, Deputy Chief

E. C. Maxwell, Administrative Officer

L. L. Sprecher, Secretary

T. L. Mangum, Secretary

The Reactor Radiation Division (RRD) has the dual functions of operating

the NBS Reactor (NBSR) and using neutron scattering methods for the

study of materials. The first function includes not only the operation

of the reactor, but also providing sample irradiation services for a large number of users. The second function includes, in addition to

Division materials research programs, serving as a focal point of neutron

scattering expertise for many other programs within and without the

Bureau.

A major part of the overall Reactor Division 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 FY80 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.

Table 1. Collaborative Interactions

No. of Personnel

FY 80

RRD Permanent Scientists 12

Non-RRD Participants

Other NBS 21

Other Agency 39

University 30

Industrial 1

0

Total Non-RRD 100

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.

457
Table 2. Independent Programs

No. of Personnel

FY 80

Other NBS 35

Other Agencies 20

Universities 18

Total 73

These tables demonstrate the extensive utilization of the NB.S reactor by scientists and engineers from outside the Division. They

come from 18 NBS Divisions and offices, 18 Federal agencies, and national

laboratories, and more than 25 universities and industrial laboratories.

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 basis. Others regularly spend two or three days a week at the

reactor. Bureau collaborative programs include measurements on ionic

crystals, polymers, simple liquids, surface molecules, hydrogen embrittlement, etc. Major independent (non-col 1 aborati ve) Bureau programs include

trace analysis by a neutron activation analysis, standard neutron fields

for neutron flux calibration and materials dosimetry, and precision

gamma-ray energy measurement.

Many outside organizations use the sample irradiation services

offered by the Division. Major users include the FBI, FDA, U.S. Geological Survey, the Smithsonian Institute, and the University of Maryland.

Programs range from analysis of criminal artifacts to the measurement of

pollutants in the environment.

The reactor modernization is nearing completion. The cooling tower

basin should be completed in September and the new cooling tower installed

shortly thereafter. The completion of the secondary piping modifications

will be completed in the fall.

The Safety Analysis Report in support of our application for a 20 MW

license has been completed and the additional supporting information

required to renew our operating license for another 20 years is being

prepared. Because public hearings are anticipated, the licensing process

is anticipated to take at least a year from date of submittal of the

appl i cation.

The new fuel elements from our new supplier, Texas Instruments, are starting to be delivered and the total order which should last until

about the end of calendar year 1982 should be delivered within the next

year. Unfortunately, once again the fuel element manufacturer has

succumbed to the ever-growing web of NRC regulation and will go out of

458
the fuel element business as soon as their present commitments are met.

They are also suppliers for all the large DOE research reactors and so we are joining with DOE in an attempt to establish a new vendor.

The mechanical problem with the reactor shim arms, reported last

year, has been repaired. All the shim arms and most of the other parts

(bearings, etc.) had to be replaced. The manufacture of replacement

parts and the very complex work of replacement caused a shutdown of

almost seven months. This, of course, severely reduced the reactor

utilization and many users of our irradiation services had to go elsewhere temporarily. The beam hole users had no equivalent place to go

and so were particularly hurt. The reactor was put back on line in

February 1980 and has been operating smoothly ever since.

The large number of independent programs (those that do not involve

scientific collaboration) were curtailed somewhat because of the reactor

shutdown. Nevertheless, a great deal was accomplished and is described

in the "Summary of Activities, July 1979-June 1980," (Preliminary copies

can be made available to interested groups. These programs include the

characterization of standard reference materials, environmental pollutants,

food and drugs, criminal artifacts, solar cell materials, etc., through

the use of neutron activation analysis to determine the level of trace

elements. The Center for Radiation Research continues to develop neutron

field measurement systems and to provide filtered beams for neutron

dosimetry calibration and development. New methods of analysis are being developed such as neutron methods for determining the concentration

of trace elements as a function of depth from the surface (depth profiling).

Renewed interest has been expressed by NIH in the production of fluorine-18

for use in brain research. The Quantum Metrology Group continues to

extend their work in the absolute measurement of y-ray wavelength and

the joint NBS-Uni versi ty of Maryland program in prompt y-ray trace

analysis continues to expand its area of applicability.

The scientific work of the Reactor Radiation Division and its

col laborators are summarized later in this report and details are given

in the "Summary of Activities" mentioned earlier. A few highlights will

be given here to indicate the current direction and accomplishments of

the Division.

During the past year there has been considerable research and

instrumentation development associated with our Division's competence

initiative in advanced neutron methods. Detailed design of the stateof-the art NBS small angle scattering facility has been completed, major

construction items have been completed or are under construction, the

first (25 x 25 cm) area detector has been tested successfully, and a major fraction of the data acquisition network, data analysis software,

and graphics system has been completed. SANS cooperative research

activities have been initiated with the Navy labs, SUNY, and the NBS

Metallurgy Division on metallurgical applications, and with the industrial labs and the University of Illinois on studies of magnetic correlations in spin glasses and amorphous magnets. A second full-time staff

member has been hired and two IPA Fellows have been brought in to enhance

research activities on polymers and alloy mi crostructure.

459
Other significant developments include the completion of a new,

high-intensity neutron analyzer and its successful application in the

first neutron study of a chemisorbed hydrocarbon monolayer on an industrial catalyst. We have also achieved the first observation of the

interaction of tunneling molecular impurities in with phonons in a solid. Neutron studies have been initiated on structure, critical

behavior, and spin interactions in a new class of amorphous alloys

showing a transition from ferromagnetic order at high temperature to

spin glass behavior at lower temperatures. In our neutron diffraction

and radiography task, we have continued our efforts to advance powder

diffraction and profile refinement techniques by introducing improved

lineshape analysis methods and evaluation of these techniques for

determining magnetic moments in mul ti subl attice compounds. There has

been a further expansion of our applications of high-resolution neutron

diffraction to high-technology materials, involving, e.g. , new cooperative research efforts with industrial guest workers. In our radiographic

standards and NDE projects we have completed a cooperative project with

private labs using radiographic reference methods to nondestructi vely

observe chemical mobility associated with the rundown of cardiac pacemakers and determined the optimum ratio of 6 Li/ZnS for use in high-speed

imaging systems.

During the coming year we, of course, anticipate final testing and

operation of the NBS SANS Facility and an associated increase in cooperative measurement, research, and NDE activities, most specifically in the area of polymer science, advanced magnetic materials, and in the studies

related to durability, performance, and processing of metals and alloys.

Our Division will also be engaged in the development of neutron irradiation and materials characterization techniques for use in the new NBS

program on nuclear waste. Expanded research is also anticipated in the

study of chemical processes on catalytic surfaces and on new applications

of neutron scattering methods for atomic scale studies of hydrogen in

defected and corroded alloys.

The Division's activities are organized into four primary tasks:

12161

12162

REACTOR OPERATION AND SERVICES

NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR

12163

ADVANCED TECHNOLOGIES

NEUTRON DIFFRACTION AND RADIOGRAPHIC METHODS FOR MATERIALS

51102

UTILITY AND DURABILITY

ADVANCED NEUTRON METHODS

The following sections describe these in more detail.

460
REACTOR OPERATIONS AND SERVICES

Task 12161

Shortly after the beginning of this reporting year, a mechanical problem

which developed with one of the shim arms forced an extended reactor shutdown

of nearly seven months. The problem was finally traced to a swelling of the

cadmium blade which necessitated replacement of all four blades. The replacement process which had never been done before proved to be both difficult and

complex because everything had to be done remotely due to the highly radioactive components and environment involved. In addition, a great deal of

preparation had to be made including preparation of methods and procedures,

design and construction of heavy shield cask, design and fabrication of tools

and equipment, and fabrication of critical replacement parts.

The old shim arms were the original installed in the reactor during

construction more than 12 years before. They had already lasted significantly

longer than expected due to a very effective fuel management program. The

blades had approximately two more years lifetime and were scheduled for

replacement in 1981 during the conversion to 20 MW. The shim arm replacement operations were performed entirely in-house. They were carried out

smoothly and efficiently and with absolute safety. There was little or

no exposure to personnel.

During this period several other major tasks were undertaken. They

included inspection of the reactor internal piping and overhaul of the fuel

transfer system. A new fuel element design was installed in the reactor

that will provide even greater fuel utilization efficiency, already one

of the best in the country. Significant progress was made toward reactor

modernization including procurement of a new cooling tower and design of

all new or modified systems.

The reactor returned to routine operation at the end of February. The

last four months saw probably the heaviest utilization in its history. At

present, 18 NBS Divisions and offices, 18 other Government agencies and

national laboratories, and 15 universities and industrial labs involving

more than 200 scientists and engineers use more than 23 simultaneously

operable reactor facilities. This is probably the widest and most diversified

use of any reactor in the U.S.

Reactor Operations

Subtask 1 of Task 12161

T. M. Raby, J. F. Torrence

Reactor operating schedule was curtailed last year due to the replacement of the shim arms. Most of the effort of operations and engineering

personnel was directed toward returning the reactor to normal as quickly

as possible. A summary of overall statistics is presented in the following

table for the period July 1, 1979 to June 30, 1980.

461
NBSR OPERATING SUMMARY FY 80

Number of days at 10 MW 122

33%

50%

1160

1600

1.4

On-line time at 10 MW

Average U- 235 burnup

Number of Irradiations

Hours of Irradiations

Hours per Irradiation

Irradiation Services

Subtask 2 of Task 12161

N. A. Bickford, J. H. Ring

During the short period the reactor operated last year there was perhaps

the heaviest use of irradiation facilities in the history of the reactor.

Activation Analysis continued on a large scale. Among these are analyses

of foods, drugs, environmental samples, forensic investigation, development

of energy resources and raw materials, and the production of important

standard reference materials.

Among new programs that have been initiated are the establishment of

a National Environmental Sample Bank and ultraprecise analysis of atmospheric

samples from all over the world. Discussions are also underway with NIH,

the National Naval Medical Center, and Johns Hopkins for the production of

fluorine-18 in a pioneering program for direct study of functions of vital

organs and human cells.

Engineering Services

Subtask 3 of Task 12161

J. H. Nicklas, R. S. Conway

Aside from the engineering support provided to reactor operations and

experimenters, engineering services were heavily involved in three major

areas. These are the successful resolution of the shim arm problem and

subsequent replacement, reactor modernization, and procurement and inspection

of new fuel elements for future reactor use.

The shim arm problem was probably one of the most demanding ever encountered in the operating history of the NBSR. Extensive engineering,

design, fabrication, machining, and procurement were required. Engineering

services personnel were also involved in several aspects of the actual

replacement and installation of components, all performed remotely underwater. The careful planning and conduct of all operations resulted in the

smooth and efficient reassembly and reinsertion of the new assemblies into

the reactor. These were perhaps the most crucial and potentially damaging

operations of the entire project.

Production of the new fuel element design was started this year and

the first batch of elements were inspected, accepted, and delivered in time

for use in the reactor.

462
Significant progress was made toward the reactor modernization. The

new cooling tower design was completed and a contract was awarded for con- struction in the summer of 1980. Similarly the cooling tower basin design

was finalized and construction has already started. Design of the extensive

secondary piping, relocation of pumps, and a new chemical treatment center

were also completed. A portion of the new secondary system is already in

place with the balance to be completed once the new cooling tower is

installed. All electrical connections design and specifications were

also finalized. A comprehensive design plan of new nuclear, process,

and monitoring instrumentation has been prepared. Most of the components

and equipment have been specified and obtained. These will be assembled,

tested, and installed periodically whenever reactor shutdown permits.

463
~

!
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 molecular solids. The neutron inelastic, quasielastic, and magnetic scattering techniques applied provide unique

information, e.g., on phase transformations, interatom bonds, electronic

structure, sublattice magnetization, hydrogen binding 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-control 1 ed network of 11 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, Naval Research

Laboratory, Naval Surface Weapons Center, and the University of Maryland

on materials for improved microwave transmission and sonar and advanced

explosive formulations; cooperative research with industrial scientists

(Allied Chem. , G.E., IBM) on new classes of materials with potential

applications for advanced power transformers , computers, and energy

storage; and research on hydrogen in metals and prototype phase transformations in solids with other national laboratories (Argonne National

Laboratory, Brookhaven National Laboratory) and universities (University

of Illinois, University of Houston, University of Saarlande, 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) corrosion in aluminum alloys.

Plans for the coming year include: (1) expansion of our measurements of the atomic scale behavior of low level concentrations of hydrogen

in metals and alloys, including isotope effects and the study of tunneling

states of impurity-trapped hydrogen; (2) initiation of a systematic

study of the structure and magnetic properties of new transi ti on-metal - metalloid glasses; and (3) exploration with the Chemical Stability and

Corrosion Division of the application of neutron techniques to the study

of stress corrosion products in alloys.

465
Microscopic Properties of Hydrogen in Metals and Molecular Materials

Subtask 1 of 12162

J. M. Rowe, J. J. Rush, S. F. Trevino 1

, A. Magerl 2

x Guest Worker, AMRAD

2 Guest Worker, University of Munich

Examples of activities and accomplishments during the past year:

o Completed construction, installation, and testing of a new highintensity filter-analyzer for highly sensitive neutron scattering

investigations of hydrogen in metals and molecular reactions

products on catalytic surfaces.

o Completed first measurements of hydrogen dynamics in the presence

of interstitial and substitutional traps in refractory metals.

o Studied the chemisorption of ethylene on Raney nickel as a function

of temperature using neutron vibrational analysis and initiated a test of neutron scattering for i_n si tu determination of impurity

levels on industrial catalysts.

o Completed first direct measurement of the interaction of tunneling

levels of molecular impurities with phonons in an inorganic crystal

(KBr(CN ) o 0003)-

0 Completed computer simulation of the crystal dynamics of (3-phase

NbD^ to explain the character of anomalous, low-energy hydrogen

modes in this system.

0 Achieved molecular dynamic simulation of an order-disorder transformation in a diatomic molecular crystal as part of an effort to

investigate the mechanisms of redistribution of chemical reaction

energies in condensed matter.

0 Set up tripartite research program with scientists from Belgium and

West Germany, partly supported by NATO, for expanded fundamental

research on single particle dynamics and phase transitions in

metal-hydrogen systems.

466
Microscopic Properties of Magnetic and Amorphous Materials

Subtask 2 of Task 12162

J. J. Rhyne, R. C. Casella, J. Lynn 1

, H. Alperin2

N. Koon 3

, K. Hardman

1 Guest Worker, University of Maryland

2 Guest Worker, Naval Surface Weapons Center

3 Guest Worker, Naval Research Laboratory

Examples of activities and accomplishments during the past year:

o Initiated neutron studies of a new class of amorphous alloys which

show ferromagnetic order at higher temperature and spin glass

behavior at low temperature, including an examination of both the

critical properties and the spin dynamics through the transition

from ferromagnetic to spin glass order.

o Completed detailed structure study of several hydrides of Th 6 Mn 2 3

and Y 6 Mn 23 to investigate the unique changes in magnetic properties

of these compounds on hydrogenation.

o Initiated evaluation of the use of neutron profile refinement

techniques in determining magnetic moments in mul ti sub! attice

magnetic compounds.

o Developed a Greens function random phase approximation (RPA)

computer model including both exchange and crystal field contributions and applied it to explain the anomalous finite temperature

excitations of ErFe 2 and ErCo2 and the ground state spin waves in

HoCo2

.

o Expanded measurements of the crystal fields and magnetic order in a number of compounds which show coexistent phenomena of superconductivity and magnetism.

o Completed a study of spin waves in Rb MnCl 3 , a ferromagnet with

alternating strong and weak exchange couplings, and used a linear

spin wave model used to analyze the results.

o The subtask leader was a member of a nine-member delegation from

the U.S. invited to India to participate in a binational conference

on rare earth materials.

467

NEUTRON DIFFRACTION AND RADIOGRAPHIC METHODS FOR MATERIALS UTILIZATION

AND DURABILITY

Task 12163

This task utilizes the unique role of neutrons (due, e.g., to their

deep penetration, sensitivity to light atoms, and well-defined lineshapes

for precise structure analysis) in the structural analysis and non- destructive testing of materials. Task members have competences at the

forefront of measurement and analysis of materials structure, including

concentrated efforts in neutron powder diffraction and profile analysis

methods, broad expertise in radiographic measurement technology, and

state-of-the art computer controlled diffraction facilities. This

expertise is used to develop advanced neutron diffraction and radiographic methods to provide: (1) preci se structure analysi

s

essential

for effective use of materials (e.g., in batteries and chemical catalysis);

(2) nondestructive reference methods for defects, precipations , and

texture affecting metal product performance, for improved quality assurance,

e.g., in pacemaker batteries, composites, and nuclear waste containment,

and for microstructure analysis of materials in extreme environments;

and (3) neutron radi ography and beam standards for more accurate and

reliable plant and field inspections (e.g., corrosion in aircraft).

Current research and measurement activities include cooperative projects

with the Center for Radiation Research (NDE), Center for Thermodynamics

and Surface Science (properties of fluids and surfaces), and with four

CMS Divisions (materials structure and durability). This task also

directly serves the Offices of Nondestructive Evaluation and Nuclear

Safeguards. Outside interactions and cooperative research with groups

needing advanced neutron methods include NIH, NRL, Army Materials, Navy,

FDA, aviation industries, Smithsonian, Allied Chemical Co., Bell Labs,

Army, and universities on projects ranging from corrosion detection to

the structure of proteins.

Plans for the coming year include: (1) installation, testing, and

operation of the NBS small angle scattering spectrometer; (2) development

with other CMS Divisions of expanded neutron diffraction and SANS applications in alloy solidification processes and durability, and in microstructure analysis of nuclear wasteforms; and (3) further work on improved

methods for measuring and interpreting modulated structures in inorganic

materials.

Neutron Diffraction Methods and Applications

Subtask 1 of Task 12163

E. Prince, A. Santoro, B. Mozer, H. Prask 1

, C. Choi 1

, A. Wlodawer

1 Guest Worker, AMRAD

Examples of activities and accomplishments during the past year:

o Established cooperative research efforts with Bell Labs and Metronic,

Inc., on the application of high-resolution neutron diffraction to

provide critical structure information on prototype Li compounds

for electronic applications.

469
0 In our continuing efforts to advance powder diffraction and neutron

profile refinement methods, we have introduced generalized variable

lineshape refinement procedures to provide more reliable structural

analysis in many cases where strain and particle size effects

provide non-Gaussian diffraction profiles.

o Completed the first neutron diffraction data set on the enzyme

ribonuclease using the NBS-NIH flat-cone diffractometer and utilized improved x-ray and neutron data reduction and refinement

procedures to establish the configuration of the histadine sidechain critical to understanding the biochemical activity of this

enzyme.

o Completed structure refinements of model metal-oxide compounds and

ceramics as part of a continuing study of the microscopic properties

of electronic ceramics and storage battery materials in cooperation

with the Ceramics, Glass, and Solid State Science Division and NRL.

o Used neutron diffraction to determine atomic arrangements and

particle sizes in graphite-intercalation compounds.

Radiographic Methods and Standards

Subtask 2 of Task 12163

D. A. Garrett, Y. T. Cheng, M. Ganozcy, W. L. Parker 1

1 Guest Scientist

Examples of activities and accomplishments during the past year:

o Completed the cardiac pacemaker study using neutron and x-ray power

system techniques to explain the chemical kinetics of the battery

components as a function of rundown. This work was performed in

cooperation with engineers in the private sector.

o Completed the study of the validity of results obtained utilizing

the Aerotest Operations method of measuring the L/D ratio parameter

for neutron radiographic facilities.

o Completed a study to determine the feasibility of utilizing nuclear

reactors in the Washington, D.C., area for the attribution and authentication of valuable paintings. This technique utilized the

neutron- induced autoradiography method for the painting characterizati on.

o Completed the editing of the ASTM Special Publication, "Proceedings

of the NBS Symposium on Real-Time Radiologic Imaging: Medical and

Industrial Applications."

o Completed the evaluation of non-reactor based neutron radiography

facilities for the Department of the Navy.

470
o Developed a mathematical procedure to address the matrix problems

associated with nuclear waste quantification.

o Determined the optimum ratio of 6 Li/ZnS for use in high-speed

neutron imaging systems.

471
I

i
o Developed a mathematical procedure to address the matrix problems

associated with nuclear waste quantification.

o Determined the optimum ratio of 6 Li/ZnS for use in high-speed

neutron imaging systems.

471

ADVANCED NEUTRON METHODS

Task 51102

C. Glinka, N. Berk, J. M. Rowe, J. LaRock, S. Singhal 1

1 IPA Fellow

The Reactor Radiation Division was granted support starting in

FY79 under the NBS Competence Building Program to develop new and

advanced instrumentation and scientific applications in neutron scattering from materials. The initial focus of this long-range competence

building activity is small -angle neutron scattering (SANS) and its

potential for unique applications in the polymer and biological sciences,

solid state physics and magnetism, metallurgy and materials science, and

in the microscopic nondestructive testing of bulk materials. Future

activities will include the development of improved measurement capability to exploit new scientific opportunities in high-resolution, variable

wave-vector neutron spectroscopy.

Some activities and accomplishments during the past year include:

o Completion of the detailed design of the entire SANS facility

(excluding the multiple-sample control and alignment system). All

collimating shielding and evacuated flight path components are completed or under construction. Installation has begun and is

expected to be completed this coming winter.

o Successful testing of the first area detector for the SANS facility.

The second, larger (65 x 65 cm) detector is expected to be delivered

by October this year.

o Completion of a major fraction of the data-acquisition system and

interactive on-line data analysis network including technicolor

graphics capability.

o Establishment of cooperative research activities on metallurgical

applications with the Navy, State University of New York (SUNY),

BNL, and the NBS Metallurgy Division.

o Support of expanded SANS research on polymers by the NBS Polymer

Science and Standards Division and their university and industrial

col 1 aborators.

o Application of SANS combined with low-energy, inelastic scattering

to studies of and magnetic correlations and interactions in spin

glasses and magnetic superconductors.

o Initiated applications of SANS to study the kinetics of microstructural development in nickel-based superalloys which are used

routinely in aircraft turbine-blade applications.

473
.

.
ADVANCED NEUTRON METHODS

Task 51102

C. Glinka, N. Berk, J. M. Rowe, J. LaRock, S. Singhal 1

X IPA Fellow

The Reactor Radiation Division was granted support starting in

FY79 under the NBS Competence Building Program to develop new and

advanced instrumentation and scientific applications in neutron scattering from materials. The initial focus of this long-range competence

building activity is small -angle neutron scattering (SANS) and its

potential for unique applications in the polymer and biological sciences,

solid state physics and magnetism, metallurgy and materials science, and

in the microscopic nondestructive testing of bulk materials. Future

activities will include the development of improved measurement capability to exploit new scientific opportunities in high-resolution, variable

wave-vector neutron spectroscopy.

Some activities and accomplishments during the past year include:

o Completion of the detailed design of the entire SANS facility

(excluding the multiple-sample control and alignment system). All

collimating shielding and evacuated flight path components are completed or under construction. Installation has begun and is

expected to be completed this coming winter.

o Successful testing of the first area detector for the SANS facility.

The second, larger (65 x 65 cm) detector is expected to be delivered

by October this year.

o Completion of a major fraction of the data-acquisition system and

interactive on-line data analysis network including technicolor

graphics capability.

o Establishment of cooperative research activities on metallurgical

applications with the Navy, State University of New York (SUNY),

BNL, and the NBS Metallurgy Division.

o Support of expanded SANS research on polymers by the NBS Polymer

Science and Standards Division and their university and industrial

col laborators.

o Application of SANS combined with low-energy, inelastic scattering

to studies of and magnetic correlations and interactions in spin

glasses and magnetic superconductors.

o Initiated applications of SANS to study the kinetics of microstructural development in nickel-based superalloys which are used

routinely in aircraft turbine-blade applications.

473

Other Activities of the

Reactor Radiation Division

Invi ted Tal ks

Neutron Sources for Field Neutron Radiographic Applications

Conference of the American Society for Nondestructive Testing,

St. Louis, Missouri

D. A. Garrett

October 1979

Neutron Scattering Instruments Equipped With Position-Sensitive

Detectors

National Institutes of Health Instrumentation Symposium, Bethesda,

Maryland

A. Wlodawer

October 4, 1979

Application of Derivative Lattices to the Indexing of Powder

Patterns from Modulated Structures

Washington Crystal Colloquium, Geophysical Lab, Washington, D.C.

A. Santoro

October 26, 1980

Crystal Field Effects in Magnetic Superconductors

International Conference on Crystalline Electric Fields and

Structural Effects in f-Electron Systems, Philadelphia, Pennsylvania

J. W. Lynn

November 12, 1979

Exchange and Crystal Field Excitations in RFe 2 and RCo 2 Compounds

International Conference on Crystalline Electric Fields and Structural

Effects in f-Electron Systems, Philadelphia, Pennsylvania

N. C. Koon and J. J. Rhyne

November 13, 1979

Diffraction Studies of Propellant Ingredients

U.S. Army Armament R and D Command, Dover, New Jersey

H. J. Prask

December 1979

Spin Waves and Crystal Field Excitation in Rare Earth Laves-Phase

Compounds

University of Rhode Island, Physics Department Colloquium, Kingston,

Rhode Island

J. J. Rhyne

December 14, 1979

Diffraction Patterns from Modulated Structures

Centre National de la Reserche Scienti f ique , Laboratoire de Crista! lographic, Grenoble, France

A. Santoro

January 8, 1980

475
Neutron Scattering Studies of Rotation-Translation Coupling in

Orientational ly Disordered Ionic Crystals

Gordon Research Conference on Orientational Disorder in Crystals,

Santa Barbara, California

J. J. Rush

January 16, 1980

Preferential Atomic Ordering and Magnetism in R 6 (Fe 1 _ Mn ) 2 3

Compounds

University of Pittsburgh, Chemistry Department, Pittsburgh, Pennsylvania

K. Hardman

January 17, 1980

Theory of Diffusion-Mediated Excitonic Processes in Molecular

Crystals: Magnetic Field Dependence of Fluorescence and EPR

Statistical Physics Seminar, National Bureau of Standards, Gai thersburg,

Maryl and

N. Berk

January 24, 1980

Why Least-Squares . . . and Why Not?

Washington Crystal Colloquium, Washington, D.C.

E. Prince

February 1980

Methyl Reorientation and Quantum Mechanical Tunneling in Solid

Ni tromethane

Westinghouse Research Corporation, Pittsburgh, Pennsylvania

S. F. Trevino

February 7, 1980

Exchange and Crystal Field Effects in RFe 2 and RCo 2 Compounds

Solid State Colloquium, University of Maryland, College Park,

Maryl and

J. J. Rhyne

February 13, 1980

On the Existence of an "Orientational Glass" State in Mixed Crystals

of (KCN)

x (KBr) 1 _ x National Bureau of Standards, Thermophysics Division, Gai thersburg

,

Maryl and

J. M. Rowe

February 14, 1980

Phonons in Metal Hydrogen Systems

Solid State Physics Seminar, University of Illinois, Urbana, Illinois

A. Magerl

March 1980

476
Magnetic Inelastic Neutron Scattering Studies of Rare Earth Metals

and Laves-Phase Compounds

Indo-U.S. Conference on the Science and Technology of Rare Earth

Materials, Cochin, India

J. J. Rhyne

March 3, 1980

Magnetism in Amorphous Rare Earth Alloys

Indo-U.S. Conference on the Science and Technology of Rare Earth

Materials, Cochin, India

J. J. Rhyne

March 4, 1980

High Resolution Neutron Powder Diffraction and Small Angle Neutron

Scattering at the National Bureau of Standards

Winter Meeting of the American Crystal 1 ographic Association, Eufala,

Alabama

E. Prince, A. Santoro, and C. J. Glinka

March 19, 1980

Theory and Design of Instrumentation for Bridge Inspection

NBS - Mechanical Failure Prevention Group, Gai thersburg , Maryland

D. A. Bracher, D. A. Garrett, and C. Heller

April 1980

Instrumentation and Procedures for Rapid Data Collection in Neutron

Crystal 1 ography

Argonne National Laboratory, Argonne, Illinois

A. Wlodawer

April 16, 1980

Structure of Ribonucl ease-A Studied by X-ray and Neutron Diffraction

University of Chicago, Department of Theoretical Biology, Chicago,

Illinois

A. Wlodawer

April 17, 1980

Neutron Radiography of Antiquities

Joint NBS Smithsonian Series, NBS, Gaithersburg, Maryland

D. A. Garrett

May 1980

Combined X-ray and Neutron Diffraction Studies on Ribonucl ease-A

Washington Crystal Colloquium, Geophysical Lab, Washington, D.C.

A. Wlodawer

May 2, 1980

Spin Wave Scattering from RbMnCl 3 University of Rhode Island, Physics Department, Kingston, Rhode

Island

H. A. Alperin

May 2, 1980

477
Neutron Scattering Research on Hydrogen in Metals

Belgium Atomic Energy Commission, Mol, Belgium

J. M. Rowe

June 10, 1980

The Use of Neutron Scattering Technique to Study Hydrogen in Metals

National Bureau of Standards, Chemical Stability and Corrosion

Division, Gaithersburg, Maryland

K. Hardman

June 23, 1980

Neutron Diffraction Analysis of Ribonuclease

Birkbeck College, London, England

A. Wlodawer

June 27, 1980

Neutron Diffraction Analysis of Ribonuclease

Institut Laue-Langevin, Grenoble, France

A. Wlodawer

July 3, 1980

Neutron Scattering Studies of Translation-Rotation Coupling Crystals

Institut Laue-Langevin, Grenoble, France

J. M. Rowe

July 3, 1980

Neutron Diffraction and Small-Angle Scattering as Nondestructive

Probes of the Microstructure of Materials

Conference on the Mechanics of Nondestructive Testing, Virginia

Polytechnic Institute, Blacksburg, Virginia

C . J . Glinka

September 11, 1980

478
Technical and Professional Committee Participation and Leadership

American Crystallographic Association

Apparatus and Standards Committee, E. Prince, Member

American National Standards Committee, N-17

R. S. Carter, Secretary

American Society for Nondestructive Testing

Penetrating Radiation Committee, D. A. Garrett, Voting Member

Research Committee, D. A. Garrett, Voting Member

Personnel Qualifications Committee, D. A. Garrett, Voting

Member

Spring Conference, D. A. Garrett, Chairman

American Society for Testing and Materials

E-7.05: Nondestructive Testing - Neutron Radiography, D. A. Garrett, Secretary

ANS-15 Standards for Research Reactors

T. M. Raby

Argonne National Laboratory

Program Review Committee for the Intense Pulsed Neutron Source,

J. M. Rowe, Chairman

Argonne National Laboratory and Department of Energy

Facilities Review Panel on Intense Pulsed Neutron Sources,

J. M. Rowe, Chairman

Conference on Magnetism and Magnetic Materials

Advisory Committee, J. J. Rhyne, Member

Department of Energy

Neutron Scattering Review Panel, J. J. Rush, Member

Panel to Review U. S. Pulsed Neutron Scattering Research

Facilities, J. J. Rush,

Member

Fourteenth Rare Earth Research Conference

Spedding Award Committee, J. J. Rhyne, Member

Gordon Conference on Orientational Disorder in Crystals

Reorientation Phenomena in Crystals Session, J. M. Rowe,

Discussion Leader

International Conference on Crystalline Electric Fields and Structural

Effects in f-Electron Systems

Lattice Effects I Session, J. J. Rhyne, Session Chairman

479
International Conference on Ternary Superconductors

Program Advisory Committee, J. W. Lynn, Member

Magnetism Letters

Editorial Board, J. J. Rhyne, Member

March Meeting of the American Physical Society

Molecular Dynamics of Simple Liquids Session, J. M. Rowe,

Session Chairman

Oak Ridge National Laboratory

National Center for Small Angle X-ray and Neutron Scattering

Program Review Committee, J. J. Rhyne, Member

National Bureau of Standards

Radiation Safety Task Force Review Panel, J. J. Rush, Member

Research Advisory Committee, J. J. Rush, Chairman

*.

480
Publ i cations

A Robust/Resistant Technique for Crystal Structure Refinement

W. L. Nicholson and E. Prince

Acta Cryst. A (submitted)

Texture, Nondestructive Characterization

H. J. Prask and C. S. Choi

Ency. Matls. Sci. and Eng. (submitted)

Comparison of Profile and Integrated Intensity Methods in Powder

Refi nement

E. Prince

J. Appl. Cryst. (submitted)

Use of Derivative Lattices in the Indexing of Powder Patterns

A. Santoro

Acta Cryst. (submitted)

Preliminary Investigation of a New X-ray Film

S. Abrahamsson, 0. Lindqvist, L. Sjolin, and Alexander Wlodawer

J. Appl. Cryst. (submitted)

Molybdoarsinate Heteropoly Complexes. The Structure of the Hydrogentetramolybdodimethyl arsi nate (2-) Anion by X-ray and Neutron

Di f fraction

K. M. Barkigia, L. M. Rajkovic-Blazer, M. T. Pope, E. Prince, and

C. 0. Quicksall

Inorganic Chemistry (in press)

Phase Transitions in Ammonium Nitrate

C. S. Choi, H. J. Prask, and E. Prince

J. Appl. Cryst. (in press)

Refinement of Di para-anthracene

C. S. Choi and P. L. Marinkas

Acta Cryst. (in press)

Powder Neutron Diffraction Study of Chemically Prepared p-Pb0 2 Peter D' Antonio and A. Santoro

Acta Cryst. (in press)

Neutron Diffraction and Small-Angle Scattering as Nondestructive

Probes of the Microstructure of Materials

C. J. Glinka, H. J. Prask, and C. S. Choi

Proceedings of the Conference on Mechanics of Nondestructive Testing

(to be published by Plenum Press)

Preferential Ordering of Mn and Fe Atoms in Y 6 (Fe 1 _^Mn ) 2 3

K. Hardman, W. J. James, and W. B. Yelon

Journal of Physics and Chemical Solids (in press)

481
Structural Investigation of Th 6 Mn 23 D 16 by Neutron Diffraction

K. Hardman, J. J. Rhyne, K. Smith, and W. E. Wallace

Journal of the Less Common Metals (in press)

Neutron Inelastic Scattering Study of C 2 H 4 Adsorbed on Raney Nickel

R. D. Kelley, R. R. Cavanagh, J. J. Rush, and T. E. Madey

Surface Science (in press)

On the Observation of Low Energy Excitations in NbD - A Simple

Lattice Dynamical Model

A. Magerl , J. M. Rowe, and D. Richter

Phys. Rev. 3 (in press)

On the Existence of an Orientational Glass State in (KCN) (KBr)-,

Mixed Crystals

K. H. Michel and J. M. Rowe

Phys. Rev. B (in press)

Nondestructive Testing of Armament-System Components by Means of

Neutron Diffraction

H. J. Prask, C. S. Choi, and S. F. Trevino

Proc. of the Army Science Conference (1980) (in press)

Magnetic Inelastic Neutron Scattering Studies of Rare Earth Metals

and Laves-Phase Compounds

J. J. Rhyne

Proc. of the Science and Technology of Rare Earth Materials (in

press)

Magnetic Materials

J. J. Rhyne

Article for the Encyclopedia of Physics, ed. by R. G. Lerner and

G. L. Trigg, Addison-Wesl ey Publishing, Reading, MA (in press)

Coherent Neutron Scattering Study of the Vibrations of Interstitial

Deuterium in a-VD 0 7 J. J. Rush, J. M. Rowe, C. J. Glinka, N. Vagelatos, and H. E. Flotow

Phys. Rev. (in press)

Neutron Scattering Study of Hydrogen Vibrations in Polycrystal and

Glassy TiCuH

J. J. Rush, J. M. Rowe, and A. J. Maeland

Journal of Physics F (in press)

Determination of the Relationship Between Derivative Lattices

A. Santoro, A. D. Mighell, and J. R. Rodgers

Acta Cryst. (in press)

Lattice Relationships: The Determination of Matrices That Will

Relate Any Given Pair of Lattices

A. Santoro, A. Mighell, and J. Rodgers

Acta Cryst. (in press)

482
Neutron Powder Diffraction Study of the Structure of CeTa0 4 , CeNb0 4 , and NdTa0 4 A. Santoro, M. Maregie, R. S. Roth, and D. Minor

Journal of Solid State Chemistry (in press)

Refinement of the Structure of Solid Nitromethane

S. F. Trevino, E. Prince, and C. R. Hubbard

J. Chem. Phys. (in press)

A Study of Methyl Reorientation in Solid Nitromethane by Neutron

Scatteri ng

S. F. Trevino and W. H. Rymes

J. Chem. Phys. (in press)

Studies of Ribonuclease-A by X-ray and Neutron Diffraction

Alexander Wlodawer

Acta Cryst. B (in press)

Non-destructive Investigation of Texture bv Neutron Diffraction

C. S. Choi, H. J. Prask, and S. F. Trevino

J. Appl . Cryst. 12, 327-331 (1979)

Production of Ultra-Cold Neutrons Using Doppler-Shifted Bragg

Scattering and Intense Pulsed Neutron Spallation Source

T. W. Dombeck, J. W. Lynn, S. A. Werner, T. Burn, J. Carpenter,

V. Krohn, and R. Ringo

Nuc. Instr. and Meth. 1 65 , 139 (1979)

Spin Glass and Magnetic Blocking Transitions in Amorphous YFe 2 “ A

Concentrated Spin Glass

D. W. Forester, N. C. Koon, J. H. Schelleng, and J. J. Rhyne

J. Appl. Phys. 50, 7336-41 (1979).

Neutron Crystal-field Spectroscopy of CeD 2 i2

C. J. Glinka, J. M. Rowe, G. G. Libowitz, and A. Maeland

Journal of Physics: C ] 2 , 4229 (1979)

Vibrational Spectroscopy of Adsorbed Species on Nickel by Neutron

Inelastic Scattering

R. D. Kelley, J. J. Rush, and T. E. Madey

Chemical Physics Letters 66, 159-164 (1979)

Magnetic Properties of the Superconducting Alloy System (Ce 4 Ho

c )R

A Neutron Scattering Study

J. W. Lynn and C. J. Glinka

J. of Magnetism and Magnetic Materials 1_4, 179 (1979)

Amorphous Magnetic Materials - Chapter 16

J. J. Rhyne

Handbook on the Physics and Chemistry of Rare Earths, ed. by

K. A. Gschneider and L. Eyring, North Holland Publishing, Amsterdam

(1979)

483
Ground State Excitations in HoCo 2 J. J. Rhyne, N. C. Koon, and B. N. Das

Inti. J. of Magnetism and Magnetic Materials ]_4, 273 (1979)

Neutron Scattering Study of the Dynamics of KCN 5 KBr 5 J. M. Rowe, J. J. Rush, D. G. Hinks, and S. Susman

Phys. Rev. Lett. 43, 1158-61 (1979)

Neutron Powder Diffraction Study of Ta2 W0 8 A. Santoro, R. S. Roth, and D. Minor

Acta Cryst. B35, 1202-5 (1979)

An Observation of One-Dimensional Reorientation and Tunnel Splitting

of the Ground and First Excited State in a Low Barrier System:

Solid Nitromethane

S. F. Trevino

J. Chem. Phys. (Letter to the Editor) 7T_, 1973-4 (1979)

High Density Lipoprotein Recombinants: Evidence for a Bicycle

Tire Micelle Structure Obtained by Neutron Scattering and Electron

Microscopy

A. Wlodawer, J. P. Segrest, B. H. Chang, R. Chiouette, and J. N. Weinstein

FEBS Letters 104, 231-235 (1979)

Theory and Design of Instrumentation for Bridge Investigations

D. A. Bracher, D. A. Garrett, and C. Heller

Proceedings of the Mechanical Failures Prevention Group (1980)

Exchange and Crystal Field Excitations in Rare Earth Iron and Rare

Earth Cobalt Laves-Phase Compounds

N. C. Koon and J. J. Rhyne

Crystalline Electric Fields and Structural Effects in f-Electron

Systems, edited by J. E. Crow, R. P. Guertin, and T. W. Mihalisin,

Plenum Publishing, New York, p. 125 (1980).

Crystal Field Effects in Magnetic Superconductors

J. W. Lynn

Crystalline Electric Fields and Structural Effects in f-Electron

Systems, edited by J. E. Crow, R. P. Guertin, and T. W. Mihalisin,

Plenum Publishing, New York, p. 547 (1980)

Magnetic Correlations and Crystal Field Levels in the Superconductor

(Ce 73 Ho 2 7 ) Ru 2 J. W. Lynn, D. E. Moncton, L. Passell , and W. Thomlinson

Phys. Rev. B21., 70 (1980)

RPA Theory of Magnetic Excitations in Rare Earth-Transition Metal

Compounds: Application of ErCo 2 and ErFe 2 J. J. Rhyne and N. C. Koon

Int'l. J. of Magnetism and Magnetic Materials ]_5, 349 (1980)

484
Magnetoelasticity and Moment Rotation in Amorphous Rare Earth-Iron

A1 1 oys

J. Cullen, H. Alperin, M. Melamud, K. Hathaway, and J. J. Rhyne

Int'l. J. of Magnetism and Magnetic Materials 1_5, 593 (1980)

Neutron Scattering Studies of Magnetic Superconductors

J. W. Lynn and R. N. Shelton

Int'l. J. of Magnetism and Magnetic Materials ]_8, 1577 (1980)

Magnetic Excitations in TbFe2 J. J. Rhyne, N. C. Koon, and H. A. Alperin

Rare Earths in Modern Science and Technology II, Plenum Publishers,

New York, p. 313 (1980)

Neutron Scattering Studies of Hydrides of the Laves-Phase Rare

Earth Compounds RFe 2 G. E. Fish, J. J. Rhyne, T. Brun, P. J. Viccaro, D. Niarchos,

B. D. Dunlap, G. K. Shenoy, S. G. Sankar, and W. E. Wallace

Rare Earths in Modern Science and Technology II, Plenum Publishers,

New York, p. 569 (1980)

Neutron Diffuse Scattering Intensities in Niobium

J. M. Rowe and A. Magerl

Phys. Rev. B 21_, 1706-7 (1980)

Neutron Scattering Studies of (CN) Defects in KBr

J. M. Rowe, J. J. Rush, S. M. Shapiro, D. G. Hinks, and S. Susman

Phys. Rev. B2J_ , 4863-4868 (1980)

Absorption Correction for Weissenberg Diffractometers

A. Santoro and Alexander Wlodawer

Acta Cryst. A36, 442-450 (1980)

485

lb
Division Seminars

Recent Developments in Neutron Instrumentation at the Institut

Laue-Langevi

n

T. Springer

Institut Laue-Langevi n , Grenoble, France

October 4, 1979

Neutron Scattering on Magnetic Moments in Intermetallic Compounds

M. Loewenhaupt

Institut fur Festkorperforschung, KFA Julich, West Germany

November 16, 1979

Rotational Tunnelling in Solids

A. Huller

Kernforschungsanlage Julich, West Germany

January 22, 1980

Theory of Strain Dipoles and Orientational Ordering

K. H. Michel

University of Antwerp, Antwerp, Belgium

January 22, 1980

The Magnetic Structure of Neodymium—A Hard Case to Solve

B. Lebech

Risd National Laboratory, Denmark

February 5, 1980

Single Chain Structure Factor from Combined Small Angle Neutron and

Small Angle X-ray Scattering

S. J. Bai

University of Michigan, Ann Arbor, Michigan

February 8, 1980

Light Scattering Studies of KH 2 P0 4 Near the Ferroel ectric Transition

in An Applied Field

R. Gammon

Institute for Physical Science and Technology, University of Maryland,

College Park, Maryland

February 12, 1980

Competing Interactions and Order-Di sorder Phenomena in Ammonium

Hal i des

C. Garland

Massachusetts Institute of Technology, Cambridge, Massachusetts

March 10, 1980

Hydrogen Diffusion in Metals

H. Wipf

Technical University of Munich, Munich, West Germany

April 18, 1980

486
Computer Simulation of Elastic Crystal Phases

M. Klein

National Research Council, Ottawa, Canada

April 30, 1980

Neutron Scattering Study on Benzene and Toluene Adsorbed on Graphite

Basal Planes

M. Monkenbusch

Institut fUr Festkorperforschung, Julich, West Germany

June 2, 1980

SANS Study of Hot Stretched Polystyrene

Francois Boue

Laboratoire Leon Brillouin, France

July 1980

Diagnostics of Neutron Beams

D. Alger

University of Missouri, Columbia, Missouri

July 1980

Some Recent Developments in Neutron Scattering Sources and Research

in West Germany

W. Schmatz

Kernforschungsanl age , Karlsruhe, West Germany

July 9, 1980

Three-axis Neutron Spectrometers at the ILL

R. Pynn

Institut Laue-Langevin , Grenoble, France, and Brookhaven National

Laboratory, Upton, New York

August 1, 1980

Neutron Scattering at Julich

D. Richter

Kernforschungsanlage Julich, West Germany

August 18, 1980

Books

The Rare Earths in Modern Science

Edited by G. J. McCarthy, J. J. Rhyne, and H. Silber

Plenum Publishers, New York, 647 pages (1980)

Proceedings of the Fourteenth Conference on Rare Earth Research,

Fargo, North Dakota, June 25-28, 1979

487
Special Reports

Report of the Facilities Review Panel to the Department of Energy

on Intense Pulsed Neutron Sources

R. R. Neal, J. J. Rush, coauthor

Report to the Assistant Secretary for Research of the Department of

Energy (July 1980)

Summary Report on Some Areas of Scientific Opportunity for the

National Bureau of Standards

J. J. Rush and members of the Research Advisory Committee

Research Advisory Committee Report to the Director (December 1979)

488

t
439
490

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MBS-114A irev. 9-78)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 80-2108L; AecBMio* No.

.VV-.v; «:v- - 'Y .<-••>* Ai ...

,3* Redptesf$ Accession Nc~

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4. TITLE AND SUBTITLE

Center for Materials Science Technical Activities 1980

5. Publication Date

iVPerfonfHOtOrganrzatioA Code

7. AUTHOR(S)

John B. Wachtman, Jr., John D. Hoffman

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

Tfl* PnjjorS/Task/Sor* Unit K&,

|R; -Y >-t; ~ Y

*"

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADORESS (Street, city. State, ZIP) 13. Type of Report & Period Covered

14» Sponsoring Agency Tide

15. SUPPLEMENTARY NOTES

| j Document describes a computer program; SF-185, FIPS' Software Summary, is attached.

16. ABSTRACT (A 200-word or leaa factual summary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.) The Center for Materials Science is part of the National Measurement Laboratory,

one of the principal laboratories comprising the National Bureau of Standards. The

Center is organized in six Divisions, each having responsibility in different areas

of materials science appropriate to the major classes of materials — metals,

polymers, and ceramics and glass. These Divisions vary in their balance between

theory and experiments, between direct standards work and research, and in their

orientation toward industrial and Government needs and the needs of other components

of the scientific and technical community. This volume summarizes the technical

research activities and accomplishments of the six Divisions of the Center for

Materials Science for Fiscal Year 1980.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the lirat letter ol the first key word unleaa a proper name;

separated by semicolons) Center for Materials Science; Ceramics Glass and Solid State Science

Division; Chemical Stability and Corrosion Division; Fracture and Deformation Division; FY80 Technical Activities; Metallurgy Division; Polymers Science and

Standards Division; Reactor Division

18. AVAILABILITY i ^Unlimited

For Official Distribution. Do Not Release to NT1S

Order From Suo. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

Order From National Technical Information Service iNTIS), Springfield, VA. 22161

19. SECURITY CLASS 21. NG. OF

(THIS REPORT; PRINTED PAGES

UNCLASSIFIED 455

20. SECURITY CLASS 22. P-ice (THIS PAGE)

$33.50

UNCLASSIFIED
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