NBSIR 80-1 996 /S

Technical Activities 1979

John D. Hoffman, Director

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

John B. Wachtman, Jr., Director

Center for Materials Science

National Bureau of Standards

U.S. Department of Commerce

Issued March 1 980

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 80-1996

TECHNICAL ACTIVITIES 1979

John D. Hoffman, Director

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

John B. Wachtman, Jr., Director

Center for Materials Science

National Bureau of Standards

U.S. Department of Commerce

Issued March 1 980

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

Luther H. Hodges, Jr., Deputy Secretary

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

In this volume we summarize the FY79 technical activities of the

Center for Materials Science. The purpose of this report is to provide

current information to the materials science community about the present

directions of the NBS efforts in materials science. Requests for reprints

of individual papers cited in this report should be addressed to the

authors.

TABLE OF CONTENTS

Page

I. INTRODUCTION 3

II. TECHNICAL ACTIVITIES 11

CENTER FOR MATERIALS SCIENCE OFFICE,

John B. Wachtman, Jr, Director 15

Signal Processing, Imaging, 16

Fracture Theory 17

Theoretical Materials Stability 18

Other Center Activities 20

CHEMICAL STABILITY AND CORROSION DIVISION,

Thomas D. Coyle, Chief 31

Corrosion and Chemical Stability of Materials in

Service Environments 32

High Temperature Chemical Stability of Materials

for Processing and Service 54

Other Division Activities 68

FRACTURE AND DEFORMATION DIVISION,

Richard P. Reed, Acting Chief 92

Fracture Mechanisms and Analyses 95

Durability of Ceramics and Composites 99

Elastic-Plastic Fracture Mechanics 110

Other Division Activities 118

POLYMER SCIENCE AND STANDARDS DIVISION,

Ronald K. Eby, Chief 143

Dielectric Plastics Design and Performance 147

Polymer Standards for Control and Equity 164

Chemical Durability of Polymers in Use 185

Migration and Durability of Plastics in Use 191

Mechanical Durability of Plastics for Design and Use . . 200

Tests, Standards, and Characterization for Manufacturing

and Durability of Dental and Medical Materials 218

Other Division Activities 229

v

METAL SCIENCE AND STANDARDS DIVISION,

Robert Mehrabian, Acting Chief 257

Metallurgical Processing for Alloy Durability 260

Alloy Properties Science for Structure Characterization . 268

Alloy Durability for Wear and Implant Applications .... 282

Metallurgical Chemistry for Durability 290

Other Division Activities 298

CERAMICS, GLASS, AND SOLID STATE SCIENCE DIVISION,

H. P. R. Frederik.se, Chief 314

Structural Chemistry for Ceramic Processing and

Durability 318

Structural Methods for Processing, Manufacturing,

and Durability 327

Properties, Structure, and Standards for Glass and

Optical Materials 343

Durability of Ceramics and Glass in Service Environments 369

Other Division Activities 375

REACTOR RADIATION DIVISION,

Robert S. Carter, Chief 394

Reactor Operations and Services 397

Neutron Scattering Characterization of Materials

for Advanced Technologies 399

Neutron Diffraction and Radiographic Methods for

Materials Utilization and Durability 402

Other Division Activities 405

vi

CENTER FOR MATERIALS SCIENCE

1

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 327 staff members; ~ 72 percent are professionals, of

which 68 percent hold Ph.D. degrees. The operating budget of the

Center for FY 1979 amounted to ~ $18. 8M.

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

support the private sector and other Government agencies in the most

effective application and utilization of materials — metals, polymers,

and inorganic materials. Center activities currently focus on those

aspects of materials research involving processing science, structure/

property science, and durability science. More specifically the Center

0 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 ocher essential areas in the materials

science discipline.

0 Provides government, industry, universities, and consumers with

essential standards, measurement methods, data, concepts, and

information concerning metals, polymers, and inorganic materials.

0 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.

0 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.

0 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 resoonsibilities in different areas of materials science. 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 technological community. The research activities of the Divisions are structured according to a task system; each task has specific goals.

3
objectives, and milestones which support the overall goals of the Center.

The following listing tabulates the tasks for each Division. Detailed

description of FY79 technical activities encompassed by the various

tasks is given in section II of this report.

Task Numbers, Titles, and Leaders

Center Office

12101 Materials Measurement Services

Chemical Stability and Corrosion Division

J. B. Wachtman, J

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 Science and Standards Division

12142 Alloy Structure, Properties, and

Standards for Quantitative Characterizati on

J. A. Simmons

12143 High Temperature Processes for

Durabi 1 ity

J. R. Manning

12144 Alloy Durability for Wear and

Implant App 1 i cations

A. W. Ruff

12145 Metallurgical Chemistry for

Durabi 1 i ty

L. H. Bennett

4
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

12163 Neutron Diffraction and Radiographic

Methods for Materials Utility and

Durability

J. J. Rush

5

7
OFFICE OF THE DIRECTOR

NATIONAL MEASUREMENT LABORATORY

Associate Director

for Planning

Senior Executive Officer

Associate Director

for Measurement

Services

Office of Domestic and

International Measurement

Standards

Office of Weights and Measures

Office of Measurement

Services

Office of

Advanced Scientific

Research

Deputy Director

for Programs

Deputy Director

for Resources

and Operations

Office of Nondestructive

Evaluation

Office of Environmental Measurements

Office of Standard Reference

Materials

Office of Standard Reference Data

Office of Measurements for Nuclear Safeguards

Office of Recycled Materials

Center for Absolute Physical

Quantities

Center for Radiation Research

Center for Thermodynamics and

Molecular Science

Electrical Measurements and

Standards Division

Atomic and Plasma

Radiation Division Surface Science

Division

Temperature Measurements and

Standards Division

Nuclear Radiation

Oivision Chemical Kinetics

Oivision

Length and Mass

Measurements and

Standards Division

Radiation Physics

Division

Chemical

Thermodynamics

Division

Time and Frequency Radiometric Thermophysics

Division Physics Division Division

Quantum Physics Radiation Source Molecular

> Division and Instrumentation Spectroscopy

Division Oivision

Center for Analytical

Chemistry

Inorganic

Analytical Research

Division

Organic Analytical

Research Division

Gas and

Particulate Science

Division

Center for Materials Science

Chemical Stability

and

Corrosion Division

Fracture and

Deformation

Division

Polymer Science

and Standards

Division

Metal Science and Standards Division

Ceramics, Glass,

and Solid State Science Divisioni I _

Reactor Radiation | Division

ll
DIRECTOR

Deputy Director

ASSOCIATE DIRECTOR FOR

PROGRAMS, BUDGET & FINANCE

Program Office

Budget Office

Office of the Comptroller

Planning Office

EEO PROGRAM

COORDINATOR

DIRECTOR OF ADMINISTRATIVE &

INFORMATION SYSTEMS

Center for Information Systems

Center for Facilities Management

Public Information Division

Personnel Division

Management & Organization Division

NATIONAL ENGINEERING

LABORATORY

Center for Applied Mathematics

Center for Electronics & Electrical Engineering

Center for Mechanical Engineering &

Process Technology

'Center for Building Technology

Center for Fire Research

Center for Consumer Product Technology

. Center for Field Methods -

OFFICE OF THE DIRECTOR

NBS/BOULDER LABORATORIES

NATIONAL MEASUREMENT

LABORATORY

Center for Absolute Physical Quantities

Center for Radiation Research

Center for Thermodynamics & Molecular

Science i Center for Analytical Chemistry

Center for Materials Science

INSTITUTE FOR COMPUTER

SCIENCES & TECHNOLOGY

Systems & Software Division

Computer Systems Engineering Division
I

Jl
II. TECHNICAL ACTIVITIES OF THE CENTER FOR MATERIALS SCIENCE

n

OFFICE OF THE CENTER FOR MATERIALS SCIENCE

13

OFFICE OF THE CENTER FOR MATERIALS SCIENCE

John B. Wachtman, Jr., Director

Elio Passaglia, Deputy Director

Samuel J. Schneider, Special Assistant for Programs

Bruce W. Steiner, Special Assistant for Planning and Programming

Melvin Linzer, Leader, Signal Processing and Imaging Group

Robb M. Thomson, Center Scientist

John W. Cahn, Center Scientist

Marge M. Barbosa, Secretary

Delores J. Covey, Secretary

Ellen T. King, Secretary

M. Jocelyn Castle, Senior Administrative Officer

Ebbie C. Maxwell, Administrative Officer

Jean M. Simon, Administrative Assistant

Marian L. Slusser, Administrative Assistant

Patricia H. Perkins, Administrative Aid

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 are of particular interest:

0 The Center's program on Materials Durability will be significantly

enhanced in FY 1980 through increased activities in the areas of

corrosion, fracture, and additive migration in polymers.

° The formal long-range plan (five year) was up-dated by the revision

of specific elements. Commensurate with this, the Center developed

detailed plans for possible programs on 1) the Durability of Structural

Composites, and 2) Materials Transformation Science for improved

materials processing.

0 In an effort to expand Center competences, work was started this

past year on the development of facilities and research on small

angle neutron scattering (SANS) at the NBS Reactor. Work on the

facility is in the Reactor Radiation Division with the first

research to be performed by that Division and the Polymers

Division. In FY 1980 the Center for Materials Science and the

Center for Absolute Physical Quantities will undertake work to

utilize the Brookhaven Synchrotron high intensity x-ray source.

Measurement Services

Although most of the program planning and

the Center takes place in the six Divisions, a Services, in the Center Office takes a general

science. This task assures adequate attention

and opportunities, particularly those that may

laboratory activity in

single task, Measurement

view of American materials

to major new challenges

affect two or more Divisions.

15
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.

Technical Activity

Center staff have participated in the senior management activity of

a number of professional societies, the National Academy of Engineering,

the American Ceramic Society, the American Society for Metals, the

American Society for Testing and Materials, the Federation of Materials

Societies, the National Research Council, the Optical Society of America,

and the Society for Photooptical Instrumentation Engineers. The staff

also participated in the National Materials Advisory Board Conference on Materials for Energy Conversion, and formal and informal Congressional

hearings on materials durability and Federal materials policy.

The staff have worked closely with other agencies to develop specific

programs including materials programs for the Department of Transportation

and the Department of Energy. Center scientists have worked particularly

closely with the American Physical Society including the Solid State

Division and a special group studying the prospects and status for

photovoltaic, low energy conversion.

Signal Processing, Imaging

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

Postdoctoral Research Associate

In the past year emphasis was placed on the development of

computer-based imaging methodology. Two papers were published on convolution/backprojection methods for producing ul trahigh-resol ution reflectivity images using enclosing and partially-enclosing apertures. Both

circular arrays for 2-D imaging and spherical (as well as hemispherical)

arrays for 3-D imaging were analyzed. Narrowband, wideband, and optimum

transmit waveforms were considered and detailed computer simulations

were carried out for a variety of potential experimental situations. A

method was developed for tomographic reconstruction from restricted

projections using iterative revisions in image and transformed spaces.

A preliminary investigation was made of methods for correcting velocity,

attenuation, and reflectivity images for ray refraction and of algorithms

for frequency-dependent time gain compensation. These studies are

expected to result in images with greatly improved resolution and accuracy.

Construction was initiated on a stepper-motor-control 1 ed scanner for

testing the various imaging methods.

The sensitivity of our expanding-aperture annular array system

was improved by over 20 dB and the device was successfully demonstrated

in a clinical environment. The Sonochromascope , a quantitative ultrasonic

device developed by the Signal Processing and Imaging Group and now

16
installed at the NIH Clinical Center, was shown to be capable of diagnosing cystic fibrosis and other diffuse pancreatic diseases. This is

the first time that such pathology has been detected by ultrasonic

techniques. A wideband analysis of annular array focusing was completed.

A paper was completed on the use of an optical i nterferometer to reconstruct three-dimensional ultrasound fields generated by a wideband

transducer.

A new journal, Ultrasonic Imaging (Academic Press) was inaugurated,

with Dr. Linzer as its Editor-in-Chief.

Fracture Theory

R. M. Thomson

Dr. Thomson's technical activities are focused on the problems

of fracture and in particular on atomic processes occurring at crack

tips. Most of this work has been in collaboration with Dr. E. R. Fuller,

Jr., in the Fracture and Deformation Division. The mathematical part of

this work is based on various analytical treatments of discrete lattices

in one and two dimensions in which trapping occurs. A general theory of

chemical reactivity at the tips of cracks has been developed which

incorporates the chemistry within the purely mechanical aspects of crack

growth. This work distinguishes two broad classes of chemical action:

1) that wherein molecular interactions occur ’directly between gaseous

species and the atoms at the tip, and 2) that wherein vacancy formation

in the adsorbed layer ax the crack tip is required. One feature of this

work shows how the thermodynamic limit can be obtained from the statistical mechanical treatment, and leads to the Griffith result in its full

thermodynamic generality. Another feature is to point out the strong

chemical specificity in chemically assisted fracture. We are led from

this to consider what classes of chemical species will assist fracture,

and which will strengthen the material. Thermodynamic considerations

show that a prime effect is simply the modified surface energy caused by

chemical adsorbtion, but kinetic considerations also point to the importance of bridging and other types of chemical reactions.

During the year, work with one-dimensional models has been

aole to develop predictions for how the activation energy varies with

stress, and yields a form for the stress dependence of the velocity.

Finally, we can apparently now understand the results of Wiederhorn on crack growth of glass in vacuum in terms of the variation of the radius

of the stretching to bending force laws in the atomic bonds.

Our approach to ductile fracture has borne fruit during the

past year in terms of a spate of approaches taken by other workers using

various aspects of our previous models of ductile fracture. This field

now requires experimental effort to disentangle the various theories now

extant. If our proposal with Hockey (Fracture and Deformation Division)

for studies of fracture in partially ductile materials is approved, we

will be able to pursue a joint theoretical and experimental approach to

this problem.

17
Finally, we have given some thought to the problem of fatigue,

and the role of crack closure. A model is being developed of how this

leads to harmonic generation of ultrasonic waves.

A major concern for the future is to attempt to understand how

electrochemical effects modify our results to date on atmospherically

assisted fracture; also to pursue (possibly with others at.NBS and

elsewhere) the Question of chemical specificity at crack tips.

Associated activities. During the year, I participated as a member of an American Physical Society study group to evaluate the

technical and scientific potential of photovol taics as a possible major

source of electrical power. The major conclusion was that solar photo - voltaic power is a long- term possibility, but that for it to be ultimately

viable, major scientific developments would be necessary. Scientific

opportunities exist in materials aspects of interfaces, in materials

synthesis, and in the development of photochemical fuel making processes.

Recommendations were made to the President's Office of Science and

Technology and to the Department of Energy which were important in the

design of the national R&D programs in photovoltaic power development.

Theoretical Materials Stability

John W. Cahn and John W. Christian

This work addressed fundamental factors in the stability of

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

past year they 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 reexamined. There are indications that

phase growth may be determined by the velocity necessary to overcome

disjoining pressure, which will be small. Critical experiments have

been proposed to verify the analysis: variation in pressure and ternary

additions. Perfect wetting should occur close to the critical temperature.

18
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-pai rwi se) 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.

19
**** *

Other Center Activity

Sponsored Conferences

Interamerican Conference on Materials Technology

Sao Paulo, Brazil

November 1978

International Materials Congress: Materials Aspects of World

Energy Needs

Reston, Virginia

March 1979

Diffusion-induced Grain Boundary Migration

NBS

May 1979

Fourth International Symposium on Ultrasonic Imaging and Tissue

Characterization

NBS

June 1979

IUPAC Conference on Oxides for Energy Applications

Toronto, -Canada

July 1979

Fourth Annual Conference on Materials for Coal Conversion

and Utilization

MBS

October 1979

Invited Talks

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Refractories Division, American Ceramic Society, Bedford Springs,

Pennsyl vani

a

John B. Wachtman, Jr.

October 1978

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Lehigh Valley Section, American Ceramic Society, Quakertown,

Pennsylvania

John B. Wachtman, Jr.

October 1978

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Glass Division, American Ceramic Society, Bedford Sorings,

Pennsylvania

John B. Wachtman, Jr.

October 1978

20
The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Hudson-Mohawk Valley Section, American Ceramic Society, Albany,

New York

John B. Wachtman, Jr.

October 1978

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Pacific Northwest Section, American Ceramic Society, Seattle,

Washington

John B. Wachtman, Jr.

October 1978

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Eastern Washington Section, American Ceramic Society, Richland,

Was hi ngton

John B. Wachtman, Jr.

October 1978

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

American Ceramic Society, Oakland, California

John B. Wachtman, Jr.

October 1978

The Future of Ceramics and the Ceramic Research Program of

the National Bureau of Standards

Ceramic-Metal Systems Division, American Ceramic Society,

Merritt Island, Florida

John B. Wachtman, Jr.

January 1979

Trends in Ceramic Research and the Program of the National

Bureau of Standards

Symposium on R&D Needs of Canadian Glass, Ceramic, and Allied

Industries in the Eighties, Canada Centre for Mineral and Energy

Technology, Department of Energy, Mines, and Resources, Ottawa,

and Ontario Research Foundation, Ottawa, Ontario, Canada

John B. Wachtman, Jr.

March 1979

An Overview of Materials Science Today in Relation to the Materials

Worl d

Carnegi e-Mel 1 on Institute, Washington, D.C.

John B. Wachtman, Jr.

June 1979

Trends in Ceramic Research and the Program of the National

Bureau of Standards

Western New York Section, American Ceramic Society, Buffalo,

New York

John B. Wachtman, Jr.

June 1979

21
Computerized Ultrasonic Tomography

Symposium on Ultrasonic Tissue Characterization, American Physical

Society, New York, New York

Melvin Linzer

February 1979

Improved Sensitivity Ultrasonic Inspection

Seminar on Railroad Nondestructive Evaluation

NBS

Melvin Linzer

May 1979

Tomographic Reconstruction of Reflectivity Images

2nd Meeting of the World Federation for Ultrasound in Medicine

and Biology, Miyazaki, Japan

Melvin Linzer

July 1979

Physical Aspects of the Fracture of Materials

Physics Department, Pennsylvania State University

University Park, Pennsylvania

Robb M. Thomson

February 1979

Brittle Fracture in a Partially Ductile Material

Materials Science Center, Pennsylvania State University,

University Park, Pennsylvania

Robb M. Thomson

February 1979

Understanding Materials Reliability - The Mechanisms of Fracture

NDE Conference, La Jolla, California

Robb M. Thomson

July 1979

The Economic Effects of Corrosion

Congressional Meeting on Corrosion

Washington, D.C.

E. Passaglia

1979

The Economic Effects of Corrosion

ACS Conference on Corrosion and Wear

Washington, D.C.

E. Passaglia

1979

The National Cost of Corrosion

Conference on Materials Solution to a National Problem

Washington, D.C.

September 1979

22
The Program of the Center for Materials Science

Department of Energy

Germantown, Maryland

E. Passaglia

September 1979

Long-range Planning at NBS

Committee on Research and Technical Planning

ASTM, Philadelphia, Pennsylvania

E. Passaglia

November 1978

Standards Activities at NBS

Committee on Research and Technical Planning

ASTM, Philadelphia, Pennsylvania

E. Passaglia

July 1979

Publ i cations

An Overview of Materials Science Today in Relation to the

Materials World

John B. Wachtman, Jr.

Proceedings of National Symposium on Wear and Corrosion, American

Chemical Society, Washington, D.C., June 1979

Wideband Annular Array Response

D. R. Dietz, S. J. Norton, and M. Linzer

1978 IEEE Ultrasonic Symposium, pp. 206-221, IEEE

Cat. #78 CH 1344-1 SU (1978)

Expandi ng-Aperture Annular Array

D. R. Dietz, S. I. Parks, and M. Linzer

Ultrasonic Imaging 1, 56-75 (1979)

A Comprehensive Ultrasonic Tissue Analysis System

M. Linzer, S. I. Parks, S. J. Norton, F. P. Higgins, D. R. Dietz,

R. S. Shideler, T. H. Shawker, and J. L. Doppman

Ultrasonic Tissue Characterization II , M. Linzer, Ed.,

pp. 255-265, NBS Special Publication 525 (1979)

The SonoChromascope

M. Linzer and S. I. Parks

Proceedi ngs of the IFIP TC-4 Worki nq Conference on Computer

Aided Tomography and Ultrasonics in Medicine , P. J. Raviv,

J. F. Greenleaf, and G. T. Herman, Eds., pp. 73-76, North

Holland Publishing Co., Amsterdam, The Netherlands (1979)

Ultrasonic Reflectivity Tomography: Reconstruction with

Circular Arrays

S. J. Norton and M. Linzer

Ultrasonic Imaging 1, 154-184 (1979)

23
Engineering Aspects of Medical Ultrasonic Imaging: A Few

New Directions (in Japanese)

T. Sato and M. Linzer

Japanese J. Clin. Med. (special issue on "Body Imaging"),

37, 148 (1979)

Ultrasonic Reflectivity Imaging in Three Dimensions: Reconstruction with Spherical Arrays

S. J. Norton and M. Linzer

Ultrasonic Imaging 1, 210-231 (1979)

Internal Friction and Sodium Transport in Beta Alumina

J. H. Simmons, A. D. Franklin, K. F. Young, and M. Linzer

J. Amer. Ceram. Soc., 62, (December 1979)

Optical Interferometric Visualization and Computerized Reconstruction of Ultrasonic Fields

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

J. Acoust. Soc. Amer. (submitted)

Tomographic Image Reconstruction from Restricted Projections

Using Iterative Revisions in Image and Transformed Species

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

Appl. Optics (submitted)

Array Imaging System with Data Selection Processing

T. Sato, M. Linzer, 0. Ikeda, and M. Hirama

J. Acoust. Soc. Amer. (submitted)

Further Development and Clinical Evaluation of the ExpandingAperture Annular Array System

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

Ultrasonic Imaging (submitted)

Numerical Analysis of the B-Scan Image: A Clinical Evaluation

of the Pancreas

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

and V. S. Hubbard

J. Clin. Ultrasound (submitted)

U1 trasoni c Tissue Character!' zati on 1

1

M. Linzer, Ed., NBS Special Publication 525 (1979)

Thermochemical Equilibrium of Multiphase Solids Under Stress

F. Larche and John W. Cahn

Acta Met., 26, 1579 (1978)

Thermodynamics of Solid and Fluid Surfaces

John W. Cahn

Segregation to Interfaces , ASM Seminar Series (1978), p. 3-23

Monotectic Composite Growth

John W. Cahn

Met. Trans. 10A 119 (1979)

24
A Microscopic Theory for Antiphase Boundary Motion and Its

Application to Antiphase Domain Coarsening

S. M. Allen and J. W. Cahn

Acta Met., 27, 1085 (1979)

On Diffusional Mass Transport in Polycrystal Containing Stationary

or Migrating Grain Boundaries

J. W. Cahn and R. W. Ball uffi

Scripta Met., ]3_ , 499 (1979)

Diffusion Induced Grain Boundary Migration

J. W. Cahn, J. D. Pan, and R. W. Balluffi

Scripta Met., 1_3, 503 (1979)

Ground State of FCC Alloys with Multi atomic Interactions

J. W. Cahn and R. Kikuchi

Acta Met. , 27, 1329 (1979)

Theory of Interphase and Antiphase Boundaries in FCC Alloys

R. Kikuchi and J. W. Cahn

Acta Met. , 27, 1337 (1979)

Interpretation of Elastic Wave Scattering by Flaws in Materials

R. M. Thomson, J. A. Krumhansl, and J. E. Gubernatis

J. Appl . Phys., 50, 3338 (1979)

Theory of Chemically Assisted Fracture

R. M. Thomson

International Conference on Mechanical Properties of Materials,

IV, Cambridge University (1979)

Solar Photovoltaic Energy Conversion

R. M. Thomson

J. Amer. Phys. Soc. (submitted)

MHD Materials, Topics in Materials Science

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

North Holland Publishing Co. (in press)

Thermodynamics and Kinetics of Martensite

J. W. Christian

Proceedings of ICOMAT Conference, MIT, Cambridge, Massachusetts

June 1979

Martensitic Transformations in Iron-Ni ckel -Carbon Alloys

J. W. Christian

Proceedings of ICOMAT Conference, MIT, Cambridge, Massachusetts

June 1979

The National Cost of Metallic Corrosion in U.S.

E. Passaglia

Proc. Tri-Services Conference on Corrosion, 1979

25
The Economic Effects of Corrosion

E. Passaglia

Proc . Congressional Conf. on Corrosion

In press

Corrosion: The Silent Scourge

E. Passaglia

Proc. ACS Conf. on Corrosion and Wear

In press

Materials Problems in Intermediate Temperature Solar Energy Systems

A. Bement and E. Passaglia

Workshop report in Proc. of Conf. on Materials Problems in Solar

Energy Systems

Materials Problems in Building and Housing

L. W. Masters and E. Passaglia

Proc. of International Conf. on Materials, 1979

In press

The Economic Effects of Corrosion Research

E. Passaglia

Editorial in Corrosion, 35_ (3) 1979

Special Reports

Development of High-sensitivity Ultrasonic Techniques for In-service

Inspection of Nuclear Reactors

M. Linzer, S. I. Parks, D. R. Dietz, and S. J. Norton

NRC Annual Report, October 1977-September 1978, Contract No. B-5680.

Books Written and/or Edited

Ultrasonic Materials Character!' zati on

H. Berger and M. Linzer, Eds., American Society for Nondestructive

Testing, 1979

Bispectral Analysis of Random Signals and Its Applications

T. Sato, M. Linzer, A. C. Kak, and K. Sasaki

In preparation

Technical and Professional Committee Participation and Leadership

American Ceramic Society

John B. Wachtman, Jr.

Past-President, and member of Executive Board

American Physical Society

John B. Wachtman, Jr.

Committee on Applications of Physics

26
PAGE

NO(SW

MISSING

CHEMICAL STABILITY AND CORROSION DIVISION

29

CHEMICAL STABILITY AND CORROSION DIVISION

Thomas D. Coyle, Chief

C. J. Lamb, Administrative Aide

M. L. Seebode, Clerk Typist

L. L. Ware, Administrative Aide

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 fiscal year 1979 are described

in the following pages. A number of these are of particular interest:

(1) Experimental studies of electrochemical "corrosion noise" have

shown that the amplitude and frequency dependence of these minute fluctuations of potential or current from a corroding metal are a sensitive

measure of the presence or absence of pitting corrosion. These observations suggest the possibility of new approaches to detection and measurement of localized corrosion.

(2) At the request of the Dutch and German governments, Division

staff members have participated in cooperative studies using NBS-devel oped

methodology for investigations of heavy-metal pollution in the Rhine

River.

(3) New techniques have been developed and validated to measure

chemical equilibria and concentrati ons of active species in hightemperature reactions of refractories with aggressive atmospheres.

These methods provide both a means for evaluating materials stability in

these conditions and an important new measurement tool for high temperature

sci ence.

(4) Research on charge transport in high-temperature solid electrolytes has resulted in the development of electrical measurement techniques

with potential for probing the nature of grain boundaries in ceramics.

The Division's 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. The other focuses on chemical

processes affecting materials durability and processing at high temperatures. A third area of activity, new in fiscal year 1979, includes

work on the chemical properties and performance of lubricants in support

of the NBS Recycled Oil Program.

31
****** rt

CORROSION AND CHEMICAL STABILITY OF MATERIALS IN SERVICE ENVIRONMENTS

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 under this task are carried out by two

groups, one emphasizing metallic corrosion and protective coatings, and

the other focusing on chemical and biological degradation processes

affecting several classes of materials:

Technical Activity

Corrosion and Electrodeposition

J. Kruger, U. Bertocci , C. F. Derr, E. Escalante, J. L. Fink, W. F. Gerhold, W. P. Iverson, C. E. Johnson, D. R. Kelley, J. L. Mullen,

F. Ogburn, B. T. Sanderson, J. Smit, J. P. Young, S. I to 1

, D. S. Lashmore 1

, and S. Wolynec2

Research Associate

2 Guest Worker

Technical activity in this area is carried out in several specific

project areas ranging from test method development through field and

laboratory studies of corrosion resistance of materials, to more basic

investigations of corrosion mechanisms, el ectrochemi stry , and coatings.

Activities in the individual projects are summarized below:

Test Methods for Corrosion

J. Kruger, J. J. Ritter, S. Ito, U. Bertocci, E. Escalante,

J. L. Mullen, and S. Wolynec

This project 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 el ectrochemi stry , surface physics, and

chemistry to a study of corrosion processes and eventually develop from

these studies simpler techniques that can be applied by testing laboratories

(1) A successful test of the validity and usefulness of the

electrochemical noise technique was accomplished. It was demonstrated

uhat this measurement technique, which analyzes small fluctuations of

potential or current associated with el ectrochemical or corrosion

32
processes taking place on a metal in an electrolyte, can detect significant

differences between pitting and non-pitting systems. As Fig. 1 shows,

noise currents of almost two orders of magnitude and a substantial

different spectrum was observed for an aluminum surface exposed to a pitting regime as compared to the same surface exposed to non-pitting

conditions. A beginning has been made on applying the electrochemical

noise technique to study the electrochemical behavior of amorphous

alloys.

(2) A new approach toward making impedance measurements for

corrosion studies has been developed. Ordinarily, in making impedance

measurements, potentials of the order of a few millivolts have to be

applied to a corroding surface. Potentials of this magnitude, which can cause a possible change in the corrosion conditions at a metal surface

have had to be applied because the currents that must be determined in

impedance measurements, resulting from the application of lower potentials,

are so low that they are swamped out by electronic noise. This is

especially true for metals with highly protective (passive) films such

as aluminum and stainless steels where high potentials have been necessary

to make impedance measurements. By coupling a newly developed low noise

potentiostat, originally developed for the electrochemical noise measurements described in (1) above, with a frequency spectrum analyser, it is

now possible to make impedance measurements by applying potentials as low as 10 6 to 10 4 volts (depending on frequency) and thereby cause

less disturbance of a corrosion process by the measurement of impedance.

Such impedance measurements are important in determining the ability of

metals and alloys to withstand exposure to environments of practical

i nterest.

In addition to the development of this new approach to impedance

measurements, improvements have been introduced that promise to enhance

data handling. The ac signals to be processed have been put in digital

form and transmitted to a computer for analysis. This method allows the

processing of a wider range of frequencies than possible with the equipment

used so far extending its application to more corrosi on-resi stant materials.

(3) In order to provide a basis for the development of measuring

techniques for the corrosion processes of steel in concrete, a systematic

study has been carried ouc in aqueous (Ca(0H) 2 , and in a sand media with

variables of dissolved oxygen, pH, and chlorine content.

A number of important results have been obtained. For example,

the onset of corrosion occurs between a pH of 11.5 to 12.5, depending

upon chloride content. The amount of dissolved oxygen governs the

corrosion rate after initiation. For a better simulation to the steel

rebar in concrete, an environment with less than 3 ppm 0 2 , more than

1 mole/1 Cl and saturated Ca(CH) 2 is being used in this study.

Electrochemical studies have also been initiated using a potentiostatic and a gal vanostatic pulse signal applied to a mortarcovered steel electrode in chloride solution. Thus far extremely low

33
NOISE

CURRENT

DENSITY,

A/cm 2

/Hz

FREQUENCY, Hz

Fig. 1. Electrochemical noise spectra for A1 in boric acid-sodium

tetraborate solution with and without chloride ion addition.

The upper spectrum was obtained for A1 under pitting conditions

(with chloride present and at a potential above the'cri tical

potential for pitting). The lower spectra are those obtained

un er conditions where pitting does not occur.

34
corrosion rates have been observed for rebars in mortar containing 0.1-1

moles/1 Cl for periods of exposure as long as 1.4 months.

(4) Work concerned with studying the factors that effect

electrochemical polarization corrosion rate measurements has been completed.

This work was carried out in cooperation with Instituto de Pesquisas

Tecnologicas of Brazil, which sent a guest worker to NBS (S. Wolynec). A

new method for obtaining polarization data was derived from chronoamnerometric investigations. This method is similar to the potentiostatic

one with two differences: (i) the polarization potential is switched

off for some minutes between two consecutive steps so as to allow the

corroding system to recover, at least partially, the conditions observed

initially; (ii) the current is determined by extrapolating the data of

the current decay curves to infinite time. It was observed that in

those curves the current holds a logarithmic relationship to the inverse

of the square root of time. The data generated by this method is in

good agreement with weight-loss and corrosion potential measurements not

only in terms of corrosion rate but also in terms of Tafel slopes. The

approach developed promises to improve the accuracy of electrochemical

corrosion rate measurements.

Localized Corrosion

J. J. Ritter and J. Kruger

This work, which is partially supported by the Office of

Naval Research, is concerned wi th 'devel opi ng techniques that will

determine the susceptibility of alloys to various forms of localized

corrosion. The emphasis in this project is on the role repassivation

plays in localized corrosion, on corrosion mechanisms under organic

coatings, and on how the initial stages of hydrogen entry are affected

by alloy structure and composition.

(1) Repassivation rate studies of current vs. time on 304

stainless steel in IN NaCl were conducted with an improved tri boel 1 ipsometric apparatus which permits observation of repassivation processes on

a time scale of the order of a millisecond. Repassivation rates for

unsensitized material were found to be essentially independent of

applied potential between -0.124 and -0.025V SCE. With sensitized 304,

the repassivation rates became significantly slower as the applied

potentials were made more positive within this same range. Repassivation

rate for unsensitized 310 stainless steel was similarily found to be

independent of potential in IN NaCl between -0.10 and +0.10V SCE.

However, sensitized 310 showed a significantly hi qher repassivation rate

than unsensitized 310 within this potential range. These data indicate

that repassivation rate studies may not be generally applicable to the

detection of sensitization in stainless steels.

(2) Studies have been initiated for making simultaneous

el 1 ipsometric and specific ion measurements on active substrates protected by transparent organic coatings while immersed in adverse media.

These studies have as their objective the elucidation of corrosion

35
mechanisms under paints. Initial experiments designed to evaluate the

effects of immersion media on optically clear acrylic and cellulose

nitrate coatings were made using gold as an inert substrate. Both

coating materials were found to give minimal ellipsometric changes in

0.05N NaCl while in a borate buffer medium they suffered swelling and

delamination. Experiments with iron coated with cellulose nitrate and

immersed in 0.05N NaCl are characterized by a gradual rise (over one

to two days) in pH under the coating accompanied by ellipsometric

changes which signify the buildup of a film at the iron-coating interface. This is followed over the next few days by a significant decrease

in pH and an ellipsometric response indicating the thinning of the film

at the iron-coating interface and possibly the onset of corrosion.

Future experiments will examine the effects of inhibitors

(e.g. Cr0 4

"

2

) either incorporated into the coatings or placed in the

immersion media. Attempts will be made to effectively characterize the

sub-coating environment and perform triboel 1 ipsometric repassivation

rate studies in a simulated sub-coating environment.

(3) In work carried out cooperatively with the Surface

Science Division concerned with the mechanism of localized corrosive

attack by hydrogen the following results were obtained using field ion

microscopy:

(a) Niobium, although suffering surface damage from

hydrogen does not seem to undergo crystal 1 ographically selective deep

damage as found for Ti and Zr subjected to similiar conditions.

(b) Significant but not deep surface defects occur

when A1 is exposed to hydrogen and tensile stress.

(c) Cathodic polarization of an Fe-24 percent Cr alloy

results in a broad array of surface effects including film formation and

surface damage.

Metal Corrosion--Sl ow Strain Rate Test

C. E. Johnson and J. Kruger

In order for the engineers responsible for the design of new coal conversion systems to select alloys resistant to stress

corrosion cracking (SCC), a reliable but rapid non-real time test is

needed to evaluate susceptibility to this failure mode for the alloys

chosen. Therefore, the objective of this task is to develop and

evaluate testing techniques that determine susceptibility to SCC in

environments of relevance to coal conversion technology. The emphasis

of this project sponsored by DoE is on technique development and not on the selection and development of candidate materials. The approach

taken to accomplish this task was to adapt and evaluate the slow strain

rate test developed by R. N. Parkins of Newcastle upon Tyne University

to coal conversion alloys and environments. With the completion of

36
testing seven coal gasification candidate materials and the discovery

that four of the seven failed by a brittle cracking mechanism, the slow

strain rate test has been shown to be a viable technique for the testing

of susceptibility to failure of alloys in simulated coal gasification

environments at a temperature of 600 °C.

Owing to a shift in sponsor priorities and reassignment of

personnel to other tasks, the project was terminated at the end of FY 78.

During the last quarter of FY 78, Type 309 SS (similiar in composition

and properties to Type 310 SS) was tested in helium and simulated coal

gasification environments at 600 °C at a strain rate of 10 6 /s. The

Type 309 SS remained ductile with no cracking; whereas, the Type 310 SS

was one of the alloys that cracked with loss of ductility when tested at

the same conditions. Photomicrographs of the microstructure of Type 309

SS revealed islands of ferrite in the austenitic structure which could

contribute to the higher ductility than was seen in Type 310 SS where no ferrite was found. Type 310 SS was obtained from another supplier and

was tested at 600 °C in helium at a strain rate of 10 6 /s. Specimens of

Type 310 SS from this supplier cracked with low ductility much the same

as the Type 310 SS specimens did that were obtained from the first

supplier. These tests seem to rule out the possibility that the first

set of Type 310 SS specimens were from a bad lot. It appears that only

the slow strain rate test can detect the cracking in Type 310 SS since

other researchers using other techniques, such as creep rupture and

standard tensile tests, have not detected cracking, but it must be

considered that each of these incorporates a different mechanistic

approach and cannot be compared directly.

The final report of this project's work has been completed.

Metal Coati ngs--El ectrodeposition

F. Ogburn, J. P. Young, and C. E. Johnson

(1) Standard Reference Material producti on--coati ng thickness

calibration standards are produced on a routine basis. This is a continuing project that produces about 3000 items each year which are ultimately sold to the metal finishing industry and its suppliers.

(2) SRM research--Each year some investigations are conducted

as a backup for the SRM production. During the past year the development

of improved techniques of preparing our primary calibration standards

was completed and a number of new calibration standards were prepared

for x-ray measurements. A new coating thickness gauge was evaluated and

set-up for routine use in the SRM program. Another investigation has

led to a reliable method of measuring the thickness of gold coatings by

using the Scanning Electron Microscope to measure the cross section of

the coating. Plans call for evaluating a new x-ray spectrometer for

measuring coating thickness and for investigating the magnetic properties

of nickel coatings as they relate to the coating process and to the

response of coating thickness gauges.

37
(3) Penetrant crack panel s--This work is concerned with the

development of dye penetrant sensitivity crack panels by electrodeposition

techniques. Such crack panels are used to evaluate an important NDE

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

measured and turned over to private and government labs for evaluation.

A new method of determining crack depth shows that the depth is 30 to 50

times crack width. This depth is beyond the critical point for affecting

dye performance according to information received from users of the dyepenetrant systems. Microscopic examinations and measurements show the

electroformed crack panels to be quite uniform and reproducible. Several

hundred crack panels may be produced from one 9 x S" nickel -copper layered

electroform. Development work is in progress to improve the adhesion of

the plastic mounting material to the nickel -copper crack panel to reduce

dye indications at the juncture.

(4) Black Coatings--A simple chemical immersion technique has

been developed which produces ultra-black surfaces on electroless

nickel -phosphorus coatings. The blackness is associated with a unique

surface morphology consisting of a dense array of microscopic conical

pores perpendicular to the surface. This structure is produced by a selective etch with nitric acid. This extremely high light-absorbing

surface can be applied to a variety of substrates, such as metals,

ceramics, glass, and plastics.

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 350 to 2100 nanometers (see Fig. 2). This

capability of the ultra-black surface of this coating may offer potential

for applications to optical devices, flat plate solar collectors, low

temperature calorimetry studies, and because of the large surface area,

as a catalyst.

Plating on Aluminum

D. S. Lashmore 1

Research Associate

The applications for plated aluminum have greatly increased

in recent years' due to the demand for a material with a high strength to

weight ratio to replace steel, not only for decorative applications but

also in cases where a material with a low inertial moment and high wear

and abrasion resistance is required. Because there is little scientific

understanding of the deposition process on aluminum, a Research Associateship was established at NBS (in FY 1977) by private industries interested

in aluminum plating. The objective of this program was the investigation

of some of the more fundamental aspects of the process.

The research effort during the past year was in the area of

anodic and immersion pretreatments for plating onto aluminum. It was

found that in all common immersion pretreatments that the dissolution of

38
o

o

o

o

o>

o

o

r**

O

o

in

o

o

CO

o

O

O

o

d

o

o

O

O

m

Figure 2. Spectral reflectance vs. wavelength of light for two samples

of the ultra-black chemically etched aeoosits of electroless nickel.

Curve referenced to BaSOu.

39

WAVELENGTH

, (

NM)
the substrate was a structure sensitive property, that is, certain

crystallographic planes dissolved at a faster rate than others in the

presence of the sodium hydroxide common to all these electrolytes. The

morphology of the deposits is also a structure sensitive property,

indeed in the case of zincated aluminum (perhaps the most common pretreatment) the deposit was found to be epitaxial on all the aluminum

principal planes and this epitaxy was characterized as, Zn: (0001)

< 1 01 0> // Al: (0001) <01 0> Zn: (0001) <1 1 20> // A1 : (110) <111> and

Zn: (0001) < 1 1 20> // Al: (111) <110>. The morphology of the deposits

was also found to be sensitive to the alloy type even though the epitaxial

relationships were not affected. The aluminum dissolution and zinc

deposition reactions were not affected by alloy type. Small additions

of ferric chloride and Rochelle salt, however, had a drastic effect on a number of process and deposit property variables such as adhesion,

morphology of deposit, enhanced aluminum dissolution, and decreased zinc

deposition. The rate of the deposition dissolution reaction, however,

was drastically affected by alloy type. It was found that a zinc iron

alloy remained on the surface following an immersion of a zinc coated

specimen in 50 percent nitric acid. The above information has aided the

development of a new aluminum plating process.

Anodic films on two high strength aluminum alloys were characterized with regard to pore size, pore density and adhesion.

Underground Corrosion of Power Lines

U. Bertocci , E. Escalante, J. L. Mullen, and J. Kruger

The use of underground cables for the transmission of electric

power has brought new corrosion problems to the electric power industry.

One of the more elusive and serious of these is the underground corrosion

of concentric neutral wires. This project is aimed at the development

of methods for the detection of dangerous corrosion conditions in these

buried concentric neutral wires.

Work on the problem of corrosion of underground power transmission lines continued during the past year, both on laboratory samples

and on actual cables buried at a special NBS site. The partial sponsorship of this work by DoE ended this year, but the project is continuing

in cooperation with the Electric Power Research Institute.

(1) The question of the effect of a.c. leakage from cables to

ground, which is believed to be an important contributory factor in

enhancing corrosion, has been attacked both at the theoretical and at

the experimental level. Last year the equation relating current to

voltage for an electrode under charge-transfer control was solved for a modulation of the electrode potential. The solution, expressed in terms

of the modified Bessel function, allows one to calculate the rectified

current as well as the other harmonic components of the faradaic current.

The results show that shifts in the d.c. electrode potential as well as enhanced corrosion might occur as a consequence of the a.c. modulation.

40
The predictions of the mathematical model have been tested and shown to

hold for electrodes under charge-transfer control. Instrumentation for

the use of FFT methods to obtain electrochemical data is being implemented.

(2) In our program to develop techniques and equipment to

measure the corrosion rate of electric cables in service, four 15 m sections of cable were buried on the corrosion test site on the NBS

grounds. An alternating current (60 Hz) was applied to two of these

cables to better simulate in service conditions. During this year

electrochemical measurements and associated equipment have been developed

to the degree that measurements are being made on a regular basis.

These measurements indicated that the cables with an imposed

a.c. were corroding at a signficantly higher rate than those without a.c.

In addition, an intentional local modification of the soil environment

made to increase the corrosion rate on a section of the cable was having

little effect on corrosion as indicated by these measurements. Prior to

removal of the cables, the imposed a.c. was turned off. Within a few

days, the corrosion rate of the cables that had the a.c. began to decrease.

After removal, all cables were cleaned and inspected and revealed that, in

fact, the cables with a.c. had suffered extensive damage compared to the

cables without a.c. and that the section of the cable in the modified

soil had undergone little additional corrosion compared to other sections

of the same cable as the electrochemical measurements had predicted.

Weight loss measurements revealed that the weight loss predicted by the

electrochemical polarization measurements were low by less than 30

percent, an acceptable error under the varying conditions in the field.

Preliminary polarization corrosion rate measurements carried

out on cables in-service and owned by the Prince William Electric

Cooperative, Manassas, Virginia, indicate that the corrosion measurements can be made under operating cable conditions.

Future studies include continued corrosion rate measurements

on the new cables with and without a.c., evaluation of current distribution

during polarization, and improving the equipment for use on in-service

cables.

In an effort to substantiate results and improve the measurement

techniques, four new sections of cable 50 m in length have been buried.

Initial data in the absence of a.c. show that the corrosion rate of

these cables is low and comparable to the first set of cables.

Corrosion Protection of Shielding Materials for Di rect-Burial

Cable in Underground Soil Environments

W. F. Gerhold

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

41
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 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 dollar 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. The performance of Type 304 stainless

steel was excellent in all of the soils. Good protection was afforded

in all of the soils by systems i ncorporati ng 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 is in preparation.

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 NBS 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 first set of "plant housings" exposed

for one year has been completed at five of the six soil sites. Exposure

of additional samples, representative of advanced technology in materials

fabrication has been initiated.

Corrosion Evaluation of Stainless Steel Alloys for Underground

Appl i cati ons

W. F. Gerhold, E. Escalante, and B. T. Sanderson

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 initated with partial

support from the American Iron and Steel Institute at six NBS 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

42
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 is currently in preparation.

Corrosion of Piling in the Sea

E. Escalante, B. T. Sanderson, and W. P. Iverson

The increased use of offshore structures in the search for

energy from the sea has led to a greater awareness of the corrosion of

steel in this environment. In 1976, for example, over a quarter of a million tons of steel were put into use for new offshore structures.

The corrosion protection of these structures intended for long-term use

is imperative.

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 lie

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.

Originally there were 93 steel piles in the study. In 1973,

26 piles were removed for physical study. This removal resulted in NBS

Monograph 158, a progress report on the information up to that time.

This winter, a final removal is being planned which will result in a final report on this long-term corrosion and corrosion protection study

of steel in sea water.

Corrosion of Oownstream Components in MHD Power Generation

Systems

J. Smit

The objectives of this program are: 1) to develop a test

method for assessing the relative corrosion resistance of alleys in

downstream components of MHD systems such as steam cooled tubes; 2) to

screen alloys for corrosion resistance under some simulated downstream

conditions; 3) to evaluate the materials subjected to the tests in 2 to

determine the conditions under which screened alloys may be suitable

candidates for i ncorporati on in the design of downstream components.

Using the simple test rig using a propane burner, specimens

of AISI 1015 steel, 310, 316, and 446 stainless steel were evaluated

after being exposed to a hot gas stream (1330 °C) containing K2 S0 4 for

four hours. The specimens were maintained at 550 °C by internal air

43
cooling. Incipient corrosion was observed in all cases sometimes as quasi -uni form wastage and sometimes as pitting. EDX analysis showed Ni

Cr, Fe, and K in pit.

Following the completion of these studies on the extant simple

test rig, extensive changes were made to upgrade the rig. The changes

were made to provide more control over test parameters and to extend the

testing capabilities of the rig to a longer term (> 100 hrs.). To

provide this control and to extend operating times, automatic equipment

was installed, and a gas handling and storage unit was constructed.

The rebuilt rig is composed of: 1) a gas handling and storage

unit for oxygen and propane, 2) an instrument unit containing a two gas

blender-controller, a mass flow controller, a thermocouple amplifier

unit and digital volt meter, 3) a vertical test chamber which houses in

descending order: a salt reservoir, burner, combustion chamber, specimen

support, and an exhaust duct.

The hot zone temperature of the rebuilt rig is now controlled

by a modified two gas bl ender-controll er located between the gas supply

and the burner in the oxygen and propane supply lines. This unit, which

permits control of both the total flow rate and the oxygen-propane

ratio, is interfaced with a thermocouple output amplifier. The specimen

temperature is controlled, again automatically, by a mass flow con- troller located in the cooling air line between the test specimen and

the air source. The gas storage and handling unit has the capacity to

hold six 1-a 220 cu. ft. oxygen cylinders and two 100 lb. propane

cylinders. At anticipated flow rates, it is expected that this capacity

will be sufficient to allow about seventy-two hours of operation. However,

provisions have been made that permit runs of unlimited duration. One

of the test parameters added to this program is the oxygen partial

pressure near the specimen surface. A Nernst probe is being prepared to

make these measurements.

In the coming year the evaluation of materials for short

(4-hour) and long (100-hour) exposure periods will continue. Test

conditions for these periods will be varied and will include oxygen

partial pressure, specimen temperature and hot gas stream additives.

Corrosion of Steel in Concrete

E. Escalante and S. Ito

The deteriorati on of bridge decks as a result of the corrosion

of steel rebars in concrete is becoming an increasingly serious problem

in those areas of the nation where deicing salts are used. This destructive action is not evident until damage is so extensive that it

makes itself visible in the form of cracks and spalls.
The objective of this program is to develop a test method for

measuring the corrosion of steel in concrete. By being able to evaluate

this corrosion action, new protective systems can be evaluated or corrective measures taken.

During this year, the first task of this study has been

completed and a second has been initiated.

The first task involved compiling a bibliography of the

literature on the corrosion of steel in concrete (NBS Special Publication

550). The search revealed 394 entries from 1964 through 1978 which are

listed by subject index in the first section and alphabetically by

author in the second section. The subject index shows those areas of

the problem where work has been performed in the past which serves as a guide for future work.

In addition, this task included a critical review of destructive

and nondestructive techniques available for measuring the corrosion rate

of steel in concrete. On the basis of this effort, several techniques

have been chosen as having possible application to corrosion studies in

concrete. The first technique is the direct measurement of weight loss

which will serve as the standard by which other methods are evaluated.

Other techniques are Stern and Geary's linear polarization, Mansfeld's

polarization resistance, Barnartt's three point method, Schwerdtfeger 1 s break in the curve, and a.c. impedance. Each has its advantages and

disadvantages which are discussed in the review.

The second task is the application of the techniques to

measure the corrosion of steel in concrete. In this portion of the

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

bars have been cast. After curing, one of the slabs was immersed in a 3.5 percent haCl solution for 36 hours to enhance corrosion. Afterwards,

it was placed 10 cm above a pool of the solution with which it is wetted

5 days a week. Because of the high resistivity of concrete, compensation

for IR is necessary during polarization measurements. This high resistivity

has also made it necessary to modify existing equipment previously used

in soil corrosion studies by raising the input impedance of the circuitry.

Preliminary polarization measurements indicate that the IR error can be

successfully compensated, allowing corrosion rate measurements to be

made.

Because d.c. potentials have been used successfully by other

laboratories to remove Cl ions from concrete, a second concrete slab is

being subjected to the opposite effect; that is, a potential that will

force the migration of Cl into the slab is being applied after the

curing process is completed. If successful, it is expected that the

corrosion rate observed on this slab will be significantly higher after

a shorter period of exposure than that found in other slabs of the same

age.

45
Automation of Field and Laboratory Corrosion Measurements

W. G. Eicke and J. E. Sims (Electrical Measurements and

Standards Division, Center for Absolute Physical Quantities)

As a result of reprogramming, W. G. Eicke and J. E. Sims of

the Electrical Measurements and Standards Division were assigned fulltime to collaborate with the Chemical Stability and Corrosion Division

(561) in this new activity. The objectives of the activity are to

improve electrical measurements in the field of corrosion through improved

instrumentation, measurement techniques, automation, and data reduction

via digital computers.

The work currently under way is directed toward assisting the

Division 561 program concerned with i_n situ corrosion rate measuring and

corrosion detection techniques for underground power cables. Primarily,

polarization and corrosion noise measurements are being employed in the

program. It is hoped that this new collaboration will result in a number of long-term benefits such as faster, continuous unattended

monitoring, more data to extract short term effects, and more effective

corrosion field data handling. This activity in support of this 561

program was initiated in the spring of 1979 and has been directed

toward both laboratory and field corrosion measurements.

(1) The activities concerned with laboratory measurements

have been directed toward a) interfacing a digital oscilloscope to an Interdata 7/32; b) establishing a communication link between Bldgs. 220

and 223; and c) developing software to reduce measurement data obtained

via the scope. User oriented software has been successfully developed

to transfer data easily between the oscilloscope and the 7/32. The data

reduction problem is well in hand. In this latter area a reasonably

general purpose user oriented program to accurately determine the

period of waveforms and do a Discrete Fourier Transform is under development

and should be complete in the near future. It is expected that the work

will also benefit corrosion-noise measurements.

(2) The activities directed toward automated field measurements

seek to develop an improved measurement system for taking underground

corrosion data in the field. Several possible approaches have been

reviewed and are still in the very early stages of evaluation. At this

time the most likely approach will be a microprocessor based measurement

system. To facilitate this work a model of an underground system is

being set up in the laboratory so that various measurement techniques

and problems using conventional measurement equipment and the 7/32 can

be investigated.

A review of various approaches to making corrosion measurements

is planned for the future to determine other areas that might benefit

from the new expertise that has been introduced into the corrosion

program from the Electrical Measurements and Standards Division.

46
Chemical and Biodegradation Processes

F. E. Brinckman, W. R. Blair, W. P. Iverson, J. A. Jackson,

K. L. Jewett, R. B. Johannesen, E. J. Parks, and J. M. Bellama 1

1 Guest Worker

The technical activity of this subtask is directed to measurement

and mechanistic characterization of chemical and biological processes

involved in the transformati on and degradation of materials. Currently,

emphasis is on organometall ic substances because of the widespread use

of organometal 1 ic materials in technology as well as the significance of

organic derivatives in the degradation, mobilization, and transport of

metallic elements in the environment. Methods to detect, identify, and

measure individual organometal species at nanogram or pi cogram levels,

urgently needed in order to assess durability, service life, and impact

of use of these materials, are being developed and applied in specific

problem areas. In cooperation with the Division's new Tribochemi stry

Group, efforts have also been initiated to apply these measurement

techniques to characterize hydrocarbon types present in used and re- refined oils and to follow transformations of additives in oil during

oxidation and wear processes. Individual project areas are summarized

below.

Speciation of Organometal 1 ic Compounds

K. L. Jewett, W. R. Blair, J. A. Jackson, E. J. Parks, and

F. E. Brinckman

The primary objectives of this continuing project are to

develop techniques for the detection, speciation, and quantitation of

organometal species at very low levels approaching or equaling concentrations in the environment. Work during the past year has emphasized

crganotin materials because of the growing applications of these as biocides and anti foul ant materials.

The fouling of ships' hulls by marine organisms results in

severe economic loss to the Navy and to the maritime industry. These

losses are due mainly to increased fuel consumption to overcome the

hydrodynamic drag of fouled hulls and to frequent periods of drydocking

required when marine growth becomes excessive. Organotin compounds have

become prominent as potential replacements for the conventional copper

oxide as the active ingredient in these coatings because of their

greater durability and possibly greater environmental compatibility.

The effectiveness of an anti fouling coating is dependent upon

the rate at which the active anti fouling agent leaches out from the

coating. Too low a leach rate does not provide adequate inhibition; too

high a leach rate is wasteful of material and may exert unnecessary

stresses on the life cycles of biota. During the past year, work has

been continued in cooperation with the Office of Naval Research and the

47
Naval Ship Research and Development Center to identify the chemical

species released from organotin antifoulants and develop techniques for

measuring release kinetics. These methods are based on separation of

organotin compounds by high pressure liquid chromatography (HPLC) and

the use of coupled atomic absorption detectors for element-specific

detection and analysis of tin-containing species.

Using these techniques, measurements of the leach rate of the

specific organotin moiety, tri butyl tin (1 +), have been made on commercially available marine paints, and similar measurements are in progress

on a number of Navy polymeric coatings. Typical results on the commercial paints are shown in Fig. 1. Although measurements of total tin

leached from tin-containing coatings have been made in other laboratories, the present NBS work is the first example of measurement of the

leach rate of a particular organotin ion. This provides a powerful

mechanistic tool as well as a meaningful basis for significant bioassays.

During the past year, significant improvements have been made

in the techniques for the separation of trial kyl tin species by liquid

chromatography. Using a strong cation exchange column with a graphitefurnace atomic absorption (GFAA) detector, it has been possible to

effect clean separations in saline media of compounds of the type R 3 SnX,

where R = phenyl, n-butyl , n-propyl , ethyl or methyl, and X is any anion

dissociated in water (as chloride). Some typical results are illustrated in Fig. 2.- Separation of compounds R 2 SnX2 is currently being

pursued.

A significant increase in sensitivity of detection of tin

species, pushing the limits of detection from nanograms down to pi co- grams, has been achieved by modification of a commercial flame photometric detector. An application of this technique will be discussed

below under "Biological Transformations. " .

Similar techniques have been used to characterize concentrated

solutions of polymeric anti foul ant materials of interest for marine

applications. By using high pressure liquid chromatography (HPLC) with

size exclusion and reverse phase bonded chromatographic columns, in

conjunction with refractive index, ultraviolet and graphite furnace

atomic absorption (GFAA) detection systems, some organotin polymer

materials have been separated into at least two tin-containing fractions

of widely different molecular weights. This inhomogeneity appears to be

real and not an artifact of the experiment. It is preferable to have

the organotin residue attached to the higher molecular weight fraction

to provide tin dissolution over a long lifetime. Experiments are in

progress to attempt to correlate the distribution of tin among fractions

of varying molecular weight with conditions of preparation. The ultimate

objective of the work is to assist the Navy by providing a molecular

level basis for development of procurement specifications for these

materials.

48
TBTF

BOTTOM

PAINT

O

CD O

^LUD/

+us£ ng 6 rf

O

CO

Figure 1. Leaching of Bu 3 Sn (.1 + ) from paint samples containing tributyltin

fluoride (TBTF). Painted wooden panels are suspended in water and the

water is analyzed for Bu 3 Sn (1+) at various intervals of time. The

observed concentrations of tin have been converted to amount of

Bu 3 Sn 0 + ) per cm2 of paint.

49

HOURS
RESPONSE

JiV-s

Figure 2. Separation of tri phenyl ti n (.1 + ) and four trialkyltin (.1 + ) ions

from one another on a strong cation exchange column. The vertical bars

give response of the GFAA detector in arbitrary units at one minute

intervals. The mixed tin compounds were injected into the LC system,

then eluted with 0.03 M ammonium acetate at a rate of 1.50 ml min" 1

, changed after 35 minutes to 2.00 ml min”1

. The smooth curve gives the

response of an ultraviolet detector, offset about one minute. The small

dip at 11 minutes arises from (C 6 H 5 ) 3 Sn (1 + ); the alkyltin species do

not ahsorb in the ultraviolet.

50
The technique of using HPLC-GFAA to speciate organometals has

been transferred to a number of other research groups. For example,

facilities based on those developed at NBS have been established at the

U. S. Navy Ship Research and Development Center and the University of

Maryland. This technique for separation and element specific detection

(i.e., speciation) developed here avoids the need for derivatization or destructive modification of the materials to be analyzed.

Our speciation methodology program involves work on several

other elements. Since 1976 this group has worked collaboratively with

the Netherlands government, through the Delft Hydraulics Laboratory and

the Soil Fertility Institute, on the speciation of toxic metals in the

environment. Particular attention has been given to compounds of

mercury, arsenic, and tin because of their actual or potential hazard.

With the demonstration, described last year, that metal-containing

compounds could be collected in the field (specifically, Rotterdam

harbor in the Rhine delta) and concentrated on a pre-column for shipment

to the Bureau for analysis, other governments with frontage on the Rhine

became interested in the Bureau's work on trace metal speciation. This

interest is responsible for an invitation tendered by the University of

Mainz to F. E. Brinckman to spend the summer of 1979 at Mainz as a visiting professor to give a lecture and laboratory course in speciation

of organometals. The Deutsche Forschungsgemei nschaft has indicated its

interest in this work by supporting the chair in Mainz to which Dr.

Brinckman has been invited, and by inviting W. P. Iverson as well to act

as a consultant on bacterial transformation of metals. A three nation

study by Switzerland, Germany, and the Netherlands to measure the introduction and transformations of tin compounds from source to mouth is now

being established, with the Bureau acting as a consultant and participant because of its demonstrated expertise in metal speciation.

NMR Studies on Transmethylation between Aquated Metal Ions

J. A. Jackson, R. B. Johannesen, and F. E. Brinckman

Methylmercury (1+) in aqueous solution is far more toxic than

inorganic mercury (2+) and has been shown to be responsible for major

outbreaks of mercury poisoning, with both crippling and fatal results.

Although methylmercury formation has been shown to be bacterial ly

produced as well as being produced by the methyl ati on of mercury (2+) by

methyl cobal ami n (a Vitamin B-12 derivative), these are not the only

paths for production of this dangerous material. It has been demonstrated in this laboratory that abiotic methyl ati on of mercury can occur

by the action of several other methylated metals, e.g., trimethyltin (1 + ):

(CH 3 ) 3 Sn

+

+ Hg++ - (CH 3 ) 2 Sn++

+ CH 3 Hg

+

. (1)

The environmental implications of this type of reaction can be appreciated. Mercury (2+), in quantities which of themselves pose no health

51
hazard, can be converted to the highly poisonous methyl mercury (1+) by

such relatively innocuous materials as trimethyltin (1+), in aqueous

solution at ordinary temperatures by abiotic means. It therefore,

becomes of great interest to learn how rapidly this transmethylation

reaction proceeds, and how it is affected by variables such as pH, pCl

,

or temperature. Nuclear magnetic resonance (NMR) spectroscopy is ideal

for this purpose. The nuclei of interest (H, Sn, Hg) all have magneti cal ly active isotopes. The kinetics of reaction (1) were measured by

proton NMR, measuring the disappearance of trimethyltin (1+) and the

formation of dimethyltin (2+) and methylmercury (!+)._ The reaction is

second order with a rate of k2 = 12.6 ± 0.58 L mol 1 s

1 at 35 °C, =

22.0 ± 1.3 kcal mol* 1

. It is a particularly fortunate circumstance that

the proton signals of interest are all well separated and can be measured independently. The analogous reaction of transalkylation where

the alkyl is ethyl or any larger group would be almost hopelessly

complex to unravel by proton NMR because of severe overlapping of

spectra. Spectra of tin-119 and mercury-199 do not suffer from this

problem; the several alkylated species will give distinct lines since

the proton signals can be decoupled from the metal spectrum. We have

repeated the kinetic study of reaction (1) above, in collaboration with

Peter Rinaldi at Florida State University, by following the NMR signal

of the tin-119 nucleus. The results were only_sl ightly different than

the proton results, viz: k2 = 13.4 ± 0.7 x 10 3L mol 1 s

1

, E = 22.5

kcal mol 1. Thus, the principle of the method has been validated and we

are prepared to measure transfer of organic groups from one metal to

another, regardless of the complexity of the proton spectrum by following the NMR signal of the metal itself. The method is, of course,

valid in studying reactions that are free of protons, such as transfer

of inorganic radicals from metal to metal (provided the reaction is not

too fast to follow).

Biological Transformations of Tin Compounds

W. P. Iverson, J. A. Jackson, and F. E. Brinckman

As a part of our continuing studies on the environmental

transformations of toxic metals consequent to the use in the materials

cycle, we showed several years ago that a strain of Pseudomonas which is common in the Chesapeake Bay was capable of methylating tin, i.e., of

converting inorganic tin to an organic (methyl) derivative. This was demonstrated directly by mass spectrometry as well as indirectly by

reaction of the biologically produced product with mercury (2+) to form

methylmercury (1+) as described previously.

During the past year, new information has been obtained on this process. We have demonstrated, by using a flame photometric detector

equipped with a narrow-band interference filter which isolates SnH

emission bands, that the organism methylates tin (4+) in its growth

medium to a material which has the same retention time as tetramethyl ti

n

in a gas chromatograph. Proper adjustment of the hydrogen-rich flame to

52
maximize SnH emission allows a minimum of 10 pg (1x10 11

g) (calculated

as tin) of tetramethyl tin to be detected. This sensitivity will allow

either biological or abiotic transformations of metals to be followed at

environmental levels. Such transformations are important, as mentioned

above, because it is becoming increasingly recognized that inorganic

materials which are in themselves innocuous, at the levels which occur,

can be changed into more hazardous substances by reactions which are as yet poorly understood.

NMR Studies of Recycled Oil

R. B. Johannesen

The country's growing dependence on imported oil, together

with localized shortages of petroleum products, makes it desirable to

reuse waste oil materials. Working in cooperation with the Bureau's

Recycled Oil Program and the Division's newly formed Tribochemi stry

Group, we have undertaken a preliminary NMR investigation of used and

re-refined oil. One major objective of the investigation is to evaluate

the application of NMR to characterize the composition of the oil in

terms of hydrocarbon types as a criterion for consistency of used or re- refined oil base stocks. It is also anticipated that the new high field

NMR system will allow study of additives in oils, particularly phosphate

esters, to define the stability, rate, and products of decomposition of

these additives. Preliminary results have been obtained by proton and

carbon-13 NMR. These show that used oil contains a considerable amount

of paramagnetic material (not further identified) both suspended and in

solution. The relative proportions of aromatic/aliphatic carbon and

hydrogen can be estimated; when reliable quantitative data have been

obtained, these ratios can be analyzed to give the polynucl ear/mononuclear aromatic ratio. No NMR spectra of other nuclei have yet been

obtained. Phosphorus-31 spectra are expected to be easy to measure with

the new NMR system to be installed at NBS late in fiscal year 1979 and

will be used to follow reactions of phosphorus-containing additives.

Lead-207 spectra may be obtainable if the lead, known to be present in

used oil, is in true solution rather than suspension. If obtainable,

such spectra will allow us to trace the conversion of lead in the internal combustion engine, and to identify the chemical forms of lead in

used oils.

53
HIGH TEMPERATURE CHEMICAL STABILITY OF MATERIALS FOR PROCESSING AND

SERVICE

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

measurement methodology, test methods, and data required to enhance

chemical durability and related performance of materials in high temperature service environments as well as methodology for prediction of

long-term materials performance in those environments.

Technical activities fall into two areas: those in which durability is governed by heterogeneous processes involving interaction of

materials with an aggressive (usually gaseous) high temperature environment, and those in which durability is governed by transport processes

within the solid.

Technical Activity

High Temperature Processes

J. W. Hastie, D. W. Bonne'll, L. H. Grabner, W. S. Horton,

E. R. Plante, P. K. Schenck, A. B. Sessoms, and K. Zmbov 1

1 Guest Worker

Technical activities in this area in fiscal year 1979 have emphasized both heterogeneous reaction processes and characterizati on of

high- temperature gaseous environments, including flames.

Vaporization and Chemical Transport Under High Temperature

Process Conditions

J. W. Hastie, D. W. Bonnell, W. S. Horton, E. R. Plante,

and K. Zmbov

Objectives of this activity are to develop new or improved

measurement techniques and apply them to the characterization of the

reactions, performance, and durability of slag and ceramic materials in

hi gh-temperature process environments, such as those pertinent to the

operation of coal gasifier and MHD plants. Problems of immediate concern

i ncl ude:

(1) Development of improved methods for identification and

quantitative 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.

54
(4) Obtaining molecular data on the rates and mechanisms of

the release of alkali and other inorganic impurities from coal minerals

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

combustion systems.

Both experimental and theoretical methods are being

developed and applied to these questions. The well-established Knudsen

effusion mass spectrometric (KMS) method has been adapted to the measurement of slag vaporization thermodynamics at low pressure and in the

presence of reactive gases such as H 2 0, H 2 , and 0 2. To deal with slag

and ceramic systems in the presence of high pressure reactive gases, a new transpi ration mass spectrometric (TMS) technique has been developed

and demonstrated. In the NBS-devel oped TMS apparatus, solids on melts

interact in an isothermal high temperature reactor with a flowing stream

of mixed reactive gas at high temperature. Downstream of the reaction

zone, a portion of the gases containing the products of vaporization and

reaction is sampled by expansion through a supersonic nozzle to form a molecular beam. This is mass-analyzed with a quadrupole mass spectrometer

coupled to the reactor-sampler. The design of the reactor and sampling

system is intended to ensure that the chemical equilibria or relative

species concentrations characteristic of the high pressure reaction zone

are unperturbed by the sampling process. Thus, quantitative measurements

of concentrations and equilibria can be made, with direct observation of

the species present in environments approaching in-service conditions.

Test application of the method to the vaporization thermodynamics of

NaCl yielded monomer and dimer vapor pressures in excellent agreement

with conventional techniques (KMS, boiling point, velocity distribution)

these measurements extended the range of temperature dependent data from ~ 1000 K to ~ 1500 K and extended by more than three orders of magnitude

the pressure range over which vapor species have been directly observed

in this system. Subsequent' appl ications of the technique to simple

alkali halide, sulfate, oxide, hydroxide, and several complex slag systems

at total pressures to ca. one atmosphere and 1700 K have yielded vapor

pressures, species concentrations, temperature dependent reaction constants,

and substrate composition dependent activities. To relate the laboratory

data to actual MHD and coal gasifier conditions, computer based thermodynamic models are being developed. Two computer programs are being

used, one being the NASA Gordon and McBride Multicomponent Equilibrium

Free Energy Minimization Program (which computes equilibrium heterogeneous

system concentrations and thermodynamic properties from data base inform

mation under ideal solution assumptions) and the other a more sophisticated

recently acquired program S0LGASMIX (Erikkson [Sweden], similar to the

Gordon and McBride code, but relaxing the ideal solution constraint)

which is applicable to non- ideal solution systems such as slag.

Principal accomplishments during FY 79 include:

(1) Completion of the construction of a new vertical high

pressure sampling mass spectrometer system (VHPMS). A schematic of the

device is shown in Fig. 1. This system is designed to sample from

55
Figure 1. Scale drawing ('to a good approximation), of the Vertical High

Pressure Sampling Mass Spectrometer shown in a flame sampling mode. An

assortment of premixed, diffusion and two phase (gas/ liquid) burner

assemblies may be coupled via a two-axis stage burning upward into the

nozzle. The beam formation, collimation, modulation and detection

process are depicted schematically stage by stage.

56
gaseous and heterogeneous systems at high pressures (ultimately 10-100

atm) and temperatures (to 1800 K) , to operate in a vertical sample flow

configuration, to handle large quantity (ca. 10 3 gm) samples, to have

greater species detection sensitivity than the existing HPMS, and to

handle particulate laden gases (e.g. , smoky flames). The system has

already operated satisfactorily at gas loads equivalent to 10 atm pressure

with 10 ppm sensitivities.

(2) Design and construction of a coupled microwave- transpiration mass spectrometric system for use both with the HPMS and VHPMS

facilities. The object of this work, which is being carried out cooperatively with scientists from the Center for Thermodynamics and Molecular

Sciences, is to develop a method for simultaneous microwave and mass

spectrometric characterization of high- temperature gas and vapor species.

The techniques described above for sampling by supersonic expansion

produce intense beams of high- temperature species in a "spectroscopical ly

cool" form which avoids excessive thermal population of excited rotational

and vibrational states. This will remove a major limitation in spectroscopic studies of the molecular species and provide the data needed for

structural assignments. Coupling to the mass spectrometer will permit

unequivocal identification of the species being examined. Quality

structural information of unambiguously identified gas phase molecules

will provide new statistical thermodynamic functions (necessary data

base information for modeling efforts) for species of importance not

accessible to classical high temperature spectroscopic methods.

(3) Development and application of a new method for determining molecular ionization cross sections for high temperature species

using the TMS approach. Utilizing the transpiration environment, where

applied gas concentrations can be precisely controlled and total system

pressures accurately measured, direct relation of observed ion currents

to external system conditions allows straightforward determination of

pertinent ionization cross sections. When applied in simple systems

under controlled conditions self consistent cross section data can be

derived for a variety of condensible as well as volatile gas species of

high temperature importance. Ionization cross sections are the single

most important factor in converting mass spectral ion intensities to

partial pressures and their determination has often been cited as an important problem in high temperature science.

(4) Vaporization characteristics of both actual and synthetic

slag systems (species identity, relative concentration, vapor pressure,

equilibrium constants, reaction enthalpies, and activity coefficients)

were examined by TMS, and their reactivity in atmospheres of variable

partial pressure of H 2 and H 2 0 determined. Complementary Knudsen effusion

mass spectrometric (KMS) data, but at much lower system pressures, were

also obtained. Both alkali metal and alkali hydroxide species were

significant reaction products. The detailed information obtained indicated

the inapplicability of ideal solution theory to slag systems and suggest

that routine application of equilibrium calculations to these systems

57
may not be adequate expositions of the true conditions in these systems.

The results of these measurements, which have not been available heretofore,

provide an important input to the modeling studies described above.

(5) TMS vaporization thermodynamic data were obtained for the

liquid systems KC1 and KOH and existing literature discrepancies concerning

vapor species and vaporization thermodynamics resolved. The relative

amounts of monomer and dimer as well as the uncertainty in the heat of

vaporization for the dimer molecules were refined. The previous uncertainties in species distribution place severe limitations on even routine

calculation of equilibrium thermodynamic properties of systems containing

these species, even relatively minor errors in the temperature dependence

of monomer/dimer ratios having a profound effect when extrapolated to

the very high temperatures and pressures typical of projected "real

world" processes and corrosion problems. It was also demonstrated that

(KC1) 2 clusters could be formed during the expansion process if the

carrier gas to salt vapor concentration was too low. This ability to

produce clusters should prove useful in future anticipated work on nucleation and condensation phenomena.

(6) The application of the TMS method to simple systems for

demonstration and acquisition of data to elucidate complex vaporization

systems has provided a unique opportunity to probe the characteristics

of the molecular beam sampling process which promises to be a major tool

for research in high temperature science. Evidence for high temperature

cluster formation, unusual fragmentation processes, and small changes in

thermodynamic functions magnified by the large available temperature and

pressure range are providing clues which have the potential of direct

access to data on molecular and electronic structure which at present is

very uncertain.

Characterization Methodology for High Temperature Gaseous

Service Environments

J. W. Hastie, D. W. Bonnell, L. H. Grabner, and P. K. Schenck

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 environments. During

fiscal year 1979 the major thrust has been toward improved combustion -Tv

diagnostic techniques and applying these to elucidating mechanisms of ' combustion modification, including flame retardance and smoke formation.

The development of the Vertical High Pressure Sampling Mass

Spectrometer, described above, provides a capability for sampling diffusion and aerodynami cal ly weak flames, and, because of its additional

pumping capacity, allows use of larger sampling orifices for sampling

parti cul ate- 1 aden environments. Experiments on smoky flames are being

initiated.

58
Major emphasis has been given in the past year to development

of optical characterization methodology for flames and other high temperature gases. A concerted effort has been to compare several approaches,

such as Raman active rotation-vibration population distributions,

OH rotational populations, and the sodium 0- line reversal technique

(electronic), to optical flame temperature measurements. The generally

excellent agreements obtained, with critical evaluation of caveats among

the techniques were presented at the Tenth Materials Research Symposium

on Characterization of High Temperature Vapors and Gases. Observations

were made via the position dependent techniques which indicated the

occurrence of temperature inhomogeneities as well as non-equilibrium

among degrees of freedom in hotter flames in/near the reaction zone.

In conjunction with the Center for Fire Research a laser

induced two line fluorescence apparatus is also being developed for

temporally and spatially resolved temperature measurements in turbulent

flames. This is an important measurement problem as most practical

combustion devices operate under turbulent conditions.

Also in conjunction with CFR, laser fluorescence and particulate

scattering experiments are in progress on smoky diffusion flames. These

experiments are designed to determine the relative role of neutral atoms

versus ions in smoke and particulate formations in an alkali seeded

flame. The increased thermal ionization of laser excited atoms (the

opto-gal vanic effect) is used to alter the neutral/ion ratio. The same

burner will also be physically coupled to the VPHMS system for mass

spectroscopic measurements to correlate with the optical particle scattering experiments.

In support of these experiments, modeling and additional

experiments have been done on the rate of ionization of highly excited

atoms. In these experiments two lasers (or a two photon absorption) is

used to place the atoms within kT of the ionization continuum, resulting

in almost total ionization. Ionization rates, which are important in

the above studies, may be deduced from these experiments. In addition,

the use of multiple laser excitation, has increased the sensitivity of

metal atom detection in flames up to three orders of magnitude (joint

with CAC). Since alkali metals are common contaminants in coal slag and

other metals are added as flame inhibitors in plastics, increased sensitivity is important.

Other accomplishments in FY 79 include measurement of OH and H atom concentrations in representative model flames by optical absorption

and emission methods to provide a needed base for planned work in alkali

seeded flames and analysis of previously obtained Raman spectroscopi

c

data on flame temperatures for HBr inhibited flames.

59
Solid-State Transport and Stability

A. D. Franklin, C. K. Chiang, A. L Dragoo, and J. R. Bethin 1

’Postdoctoral Research Associate

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

conductivity, 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 electrode-electrolyte 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 respect to processes allowing this resistance to rise in service.

At present no good technique exists for separately measuring these

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 both the gross and the atomic-scale structure, and especially

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.

This 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 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 contain 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

60
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.

We are currently studying cerium dioxide, doped with tri valent and

divalent cations, chosen both because of its relation to practical

devices and for theoretical interest as a model high-conductivity ionically

conducting ceramic. Considerable work on preparation of research material

has resulted in ceramic specimens of apparently high purity and homogeneity, and whose porosity is about an order of magnitude lower than

the lowest achieved elsewhere.

Nature of the Charge Transport Process

A. 0. Franklin, C. K. Chiang, and J. R. Bethin

The dispersion of the impedance of polycrystalline 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. Working with Y-doped Ce02 as a model for high-conductivity

ceramics, we have found we can represent the electrical properties in

terms of the equivalent circuit shown in the inset of Fig. 1. The

symbols are as follows: Cg is the geometric capacitance, R„ the lattice

resistance, Z^

b represents a contribution that is presumably the grain

boundary impedance and Z -| the impedance introduced by the interface

with the electrodes. The latter two impedances are quite well represented

with distributed time constants using the Cole-Cole distribution (K. 5.

Cole and R. H. Cole, J. Chem. Phys. 9, 341 [1941]).

The figure displays both the experimental values of impedance,

plotted in the complex plane with frequency as a parameter over the

range from 10 Hz to 1 MHz, and the values derived from a computer fit of

the equivalent circuit to the data. Current work is concerned with

demonstrating that, in dense ceramics, Z

gb

does indeed represent grain

boundary properties, and in using this new measurement tool to study how

materials preparation and treatment influence this part of the transport

behavior.

Our data show that Z , is sensitive to how the material is

gb

prepared, a fact that should allow us to determine at least seme of the

factors influencing the "grain boundary" properties.

The sensitivity of Z^

b

to preparation methods is shown by a comparison between two sets of Y-doped Ce0 2 specimens. Type M materials

were prepared by classical ceramic techniques, mixing the separate

oxides, calcining the mixture, and either pressing and sintering 1550 “C)

61
Ohms

7/25/79 RDF File# ST CH15,713,flu-RuPi

2.50E+0Z

2.00E+02

1 ,50E+02-L-

%

XM

1.00E+02

IfC9

8 •

* a

5.00E+01-4 9

? ^

x %

• - •

1 *« »

*

Figure 1. Plot of the impedance of a Y-doped Ce0 2 ceramic specimen in the

complex plane. The frequency of measurement increases from right to left

from 10 Hz to 1 MHz. The open squares are observed values, and the

asterisks show calculated values from the inset equivalent circuit with

circuit parameters chosen using a non-linear steepest-descent least-squares

computer fit.

62
or hot-pressing O 1340 °C) pellets. The mixed oxides for Type C

materials, on the other hand, were prepared by homogeneous coprecipitation from aqueous solutions of the nitrates. The impedance parameters

at about 236 °C are:

Type Cone.

Density

% Theory p , 1

SQ •

Lattice 1 cm £

"Grain Boundary"?

^qb- 105" C

qb ’ ? F

M 10 79 2.2 26 2.9 17

M 20 85 4.0 32 6.3 16

M 10 94 3.1 33 2.0 225

C 10 81 .26 45 1.6 1.7 x 10 4

C 10 95 .23 45 8.7 1.3 x 10 4

C 10 < 99.5 1.6 35 31. 0.3 x 104

Legend: * The concentration is the percent of cations represented by

t The lattice properties have been reduced to resistivity

* (p) and dielectric constant (a) using specimen geometry,

f The “grain boundary" parameters are those in the ColeCole expression = AZ ^/[l

imaginary w the circular frequency, x time given by x = AZ*Cg

b

and n the distribution parameter

For Type M materials n ~ .5, while for Type C n ~ .9.

( jwx ) ] where j is the

the relaxation

While differences in composition and porosity may be reflected somewnat

in the impedance parameters, the major difference between the two types

lies in the effective grain-boundary capacitances C ^ and is much too

dramatic to be accounted for in this way. Furthermore, the coprecipitated

materials (Type C) exhibit narrow distributions of time constants while

those for the Type M are quite broad. Thus a second major theme in

current wo^k using impedance measurements is to try to understand compositional and structural differences in tne grain boundaries of these two

types of materials to correlate with the differences in electrical

behavior.

A third major topic in the impedance area is currently getting

under way. We will be exploring the use of the impedance technique to

examine the electrochemical reactions at the electrode/electrolyte

interface, especially with respect to mixed electronic/ionic electrode

materials and the influence of the kinetics of ionic motion on the

electrode performance. We will again use Y-aoped Ce0 2 as our model

material, and will use a number of el ectrocnemical techniques to identify

the controlling processes. An important aim of the work, in addition to

delineating the el ectrochemi stry of oxygen ionization on oxide ionconducting solid electrolytes with oxide (e.g., Sn0 2 “doped ln 2 0 3 ) electrodes, will be to see how these processes appear in the impedance

measurements and how the latter may be used to observe and monitor

changes occurring during service.

63
Long Term Stability of Solid Electrolytes

A. 0. Franklin and A. L. Dragoo

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 are about completed and the anneals will be

started in the near future. In addition, by performing some anneals

under steady applied fields we can study ion drift as well. The lowerconcentration clustering is being studied using the electron spin resonance

(esr) of manganese and gadolinium ions serving as dopants in single

crystals. The esr signal reflects the symmetry of the surroundings to

the dopant ions and therefore indicates the arrangements of nearby point

defects (in our case, oxygen vacancies). Because the Mn and Gd esr

signals persist to high temperatures, thermally-activated motions of

the surrounding defects can be followed. We have obtained lightly doped

crystals from Oak Ridge and have detected both Mn

2+ and Gd3+ esr signals.

Partial reduction of the crystal, which introduces oxygen vacancies,

converts some of the Mn

2+ ions in cubic surroundings to trigonal symmetry, indicating the formation of Mn

2+

oxygen vacancy pairs. By

studying the temperature dependence of both the intensity and breadth of

this pair signal, we should be able to learn much about the kinetics of

motion of the oxygen vacancy in the pair and the energetics of formation.

64
DIVISION 561 ACTIVITIES SUPPORTING NBS RECYCLED OIL PROGRAM

During Fiscal Year 1979, the program of the Chemical Stability and

Corrosion Division was augmented by transfer into the Division of a technical group previously assigned to the Bureau's Recycled Oil Program

(ROP). The short-term objective of this Tribochemistry Group is to

provide a technical base of data and measurement methodology to support

the ROP in responding to its mandate, under the Energy Policy and

Conservation Act, to develop test procedures to establish the substantial

equivalency of new and re-refined oils.

Tribochemistry

S. M. Hsu, J. Comeford, R. S. Gates, C. S. Ku, K. N. Hartman,

D. Mathews, and R. G. Crumley 1

1 WAE

Current technical activity is directed mainly toward development

of measurement methods and standards for re-refined petroleum oil used

as automotive crankcase oils. There are four individual project areas:

Chemical and Physical Properties

J. Comeford, S. M. Hsu, and K. N. Hartman

The chemical and physical properties of a lubricating base oil

reflect the chemical composition, and hence, at least in theory, determine

the performance. There are some twenty tests commonly used to characterize basic chemical and physical properties of base oils. Most of

these are ASTM test procedures, such as viscosity, boiling point distribution, sulfur, sul fated ash, water, aniline point, etc. For the purposes

of the NBS Recycled Oil Program, each test must be evaluated for applicability and relevance for use with re-refined base oils. Some tests,

such as ash, total acid number (TAN), and halogen content, will require

modification or new test development.

During the past year, the major effort in this area had been

to establish the laboratory capability to evaluate these tests. To

facilitate development of in-house capabilities, our staff has made

extensive visits to industrial laboratories. Sixteen tests have

been set up in our laboratory. Data are being collected on

re- refined virgin base oils.

Hydrocarbon Type Analysis

S. M. Hsu, C. S. Ku, and R. G. Crumley

Lubricating oil base stocks 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

65
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 infor—

mation 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.

Progress to date in this area has included evaluation of three

analytical procedures and data are being collected on seven re-refined

lubricating base oils. Information of this type will be correlated with

physical and chemical properties and performance.

Oxidation Stability and Deposit Simulation

S. M. Hsu and C. S. Ku

In the area of performance tests for automobile crankcase

oils, the industry-accepted tests include the current engine sequence

tests (IIC, IIIC, VC, L-38), laboratory truck engine tests (1H2, 1G2,

ID, 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); vi scosi ty-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 requi rements. 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 U.S.

and in some foreign countries. Some of these Reference Oils even have

66
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.

A laboratory module has been modified to satisfy the special

safety requirements of these tests. Equipment is being set up to simulate

the engine service conditions in oxidation stability, high temperature

stability, and corrosion.

Friction and Wear

S. M. Hsu and R. S. Gates

The emphasis in this area is on the chemical aspects of friction

and wear. In re-refined base oils derived from many sources of used

oils, potential contamination by cutting oil additives, and metal

forming oils could have significant effect on friction and wear characteristics of the final product.

A laboratory module had been specially equipped to accommodate

three wear test apparatus: ring-on-block, 4-ball, and pin-and-V. Two

additional research grade wear test instruments are on order. These are

commercial apparatus modified by NBS to facilitate the collection and

analysis of wear debris. These machines will allow realistic simulation

of automotive power train wear. Other equipment acquired includes a Ferrograph and a profilometer.

A wear debris analysis procedure has been developed to examine

the chemical composition of debris. The debris is filtered and solvent

extracted into four major fractions: iron, iron oxides, organo-iron

compounds which are soluble in oil, and organo-iron compounds which are soluble in pyridine. Coupling this analysis with information obtained

from Ferrography (particle size distribution), we can monitor the basic

chemical aspects of anti -wear effectiveness of oils. The polar fractions

from the hydrocarbon type analysis area will then be examined in wearing

contacts.

67
*******

t

Other Division Activity

Invited Talks

Corrosion Protection Principles for Organic Coatings

Mobil Chemical Company, Edison, New Jersey

J. Kruger

September 19, 1978

The Effect of Soil Properties on Underground Corrosion

NACE Northeast Corrosion Control Conference, Newport, Rhode Island

E. Escalante

October 2, 1978

The Role on Noncrystalline Films in Passivation and Breakdown of

Passivation

7th International Congress on Metallic Corrosion, Rio de Janeiro,

Brasil

J. Kruger

October 5, 1978

Stress Corrosion Testing at Elevated Temperatures in Simulated Coal

Conversion Gases

7th International Congress on Metallic Corrosion, Rio de Janeiro,

Brasi

1

J. Kruger for C. E. Johnson

October 9, 1978

An Electrochemical Study of an Al-Zn-Mg Alloy

7th International Congress on Metallic Corrosion, Rio de Janeiro,

Brasil

J. Kruger

October 9, 1978

Detection and Analysis of El ectrochemical Noise for Corrosion

Studi es 7th International Congress on Metallic Corrosion, Rio de Janeiro,

Brasil

J. Kruger for U. Bertocci

October 9, 1978

Laser-Induced Chemistry

American Chemical Society, Columbus Section, Columbus, Ohio

T. D. Coyle

November 13, 1978

68
Approaches Toward Designing Corrosion Protective Coatings

Massachusetts Institute of Technology, Cambridge, Massachusetts

J. Kruger

November 30, 1978

Recent Developments in the Bio- and Environmental Chemistry of Tin

34th American Chemical Society Southwest Regional Meeting, Corpus

Christi, Texas

F. E. Brinckman

November 30, 1978

Optical and Electrochemical Studies of Corrosion

Joint Physics and Chemistry Symposium, University of Maine, Orono,

Mai ne

J. Kruger

December 1, 1978

New Corrosion Protection Principles for Organic Coatings

Dwight P. Joyce Research Center, Glidden Coatings and Resins,

Strongsville, Ohio

J. Kruger

January 16, 1979

New Approaches Toward the Design of Corrosion Protective Organic

Coati ngs

Combined meeting of Detroit Sections of Electrochemical Society and

National Association of Corrosion Engineers, Detroit, Michigan

J. Kruger

February 15, 1979

Qualitative Use of Ellipsometry to Study Localized Corrosion Processes

Ford Motor Co. Research Labs, Dearborn, Michigan

J. Kruger

February 15, 1979

The Morphology of Immersion Deposited Zinc on Aluminum

Chemical Stability and Corrosion Division Seminar, NBS

D. S. Lashmore

February 16, 1979

A Field Study on the Corrosion of Concentric Neutral Cables

National Association of Corrosion Engineers, Atlanta, Georgia

E. Escalante

March 1979

Economic Effects of Metallic Corrosion in the U.S.

National Association of Corrosion Engineers, Atlanta, Georgia

J. Kruger

March 1979

59
Underground Corrosion of Metals

National Association of Corrosion Engineers, Atlanta, Georgia

E. Escalante

March 13, 1979

Important Issues in the Breakdown of Passivity

National Association of Corrosion Engineers, Atlanta, Georgia

J. Kruger

March 13, 1979

Corrosion Induced by an Alternating Voltage. A Comparison Between

Theoretical Predictions and Experimental Results

National Association of Corrosion Engineers, Atlanta, Georgia

J. L. Mullen

March 1979

Studies on the Biomethylation of Tin, Arsenic, and Mercury

American Chemical Society, Chemical Society of Japan International

Chemical Congress, Honolulu, Hawaii

F. E. Brinckman

April 4, 1979

Applications of High Vacuum Techniques in Laser Chemistry

Introduction to Chemistry Class, NBS

J. J. Ritter

April 1979

Ultra-Black Coating for High Absorptance of Solar Energy

Institute of Environmental Science, Seattle, Washington

C. E. Johnson

April 1979

Chemical Aspects of Fire Retardancy

American Chemical Society, Western Section, Buffalo, New York

T. D. Coyle

April 17, 1979

Corrosion Enhancement Due to Large Voltage Modulations. Experimental Results for Electrodes Under Charge-Transfer Control

ASTM Meeting, San Francisco, California

U. Bertocci

May 1979

Morphology of Immersion Deposits on Aluminum

American Electroplaters 1 Society, Atlanta, Georgia

D. S. Lashmore

June 25, 1979

7Q
Corrosion in Soil

New England Gas Assoc., Gas Operations School, Boston, Massachusetts

E. Escalante

June 1979

New Developments in the Economics and Science of Corrosion

Washington Chapter-American Society of Metals, Bethesda, Maryland

J. Kruger

June 1979

Abiotic and Biogenic Transformations of Organotins in Aqueous

Media: The Problem of Speciation

Department of Chemistry, University of Noddingham, Noddingham,

England

F. E. Brinckman

July 5, 1979

Corrosion, Sagamore Army Materials

Research Conference, Bolton Landing, New York

J. Kruger

July 1979

Microbial Transformations of Heavy Metals

Xlth International Congress of Biochemistry, Toronto, Canada

W. P. Iverson

July 13, 1979

New Methods for Speciation of Bioactive Organoti nleachates from

Anti fouling Paints and Polymers

6th International Symposium on Controlled Release of Sioactive

Materials, New Orleans, Louisiana

K. L. Jewett

August 7, 1979

El 1 ipsometric Studies of Film Growth Under Organic Coatings on Iron

Fourth International Conference on Ellipsometry, University of

California, Berkeley, California

J. J. Ritter

August 1979

Soils and Underground Corrosion

Liberty Bell Corrosion Course, Philadephia, Pennsylvania

E. Escalante

September 1979

Biological and Abiotic Transformations of Organometal 1 ics in

Aqueous Media

IXth International Conference on Organometal! ic Chemistry,

University of Dijon, Dijon, France

T. D. Coyle

September 1979

71
Important Issues in the Breakdown of Corrosion

National Association of Corrosion Engineers, Canadian Regional

Meeting, Ottawa, Ontario, Canada

J. Kruger

October 1979

Economic Effects of Metallic Corrosion in the U.S.

National Association of Corrosion Engineers, Canadian Regional

Meeting, Ottawa, Ontario, Canada

J. Kruger

October 1979

A Review of Techniques for Measuring the Corrosion of Metals in

Soi 1 ASTM Underground Corrosion Symposium, Williamsburg, Virginia

E. Escalante

November 1979

The Biosphere as a Perturbation of the Cosmic Environment—The

Question of Elemental Availability and Essentiality

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

April 19, 1979

Considerations of Chemical Solubility and Biological Mobilization

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

April 20, 1979

Materials Cycl es--Natural and Anthropogenic

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

April 26, 1979

Heavy Metal Pollution—Scope and Prospect

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

April 27, 1979

What Can We—What Must We—Measure?

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

May 3, 1979

Status Report on Biogeochemical Mobilization of Heavy Metal Species

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

May 4, 1979

72
Synthesis —What Can We Expect for Heavy Metal Pollution?

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

May 10, 1979

Technology to the Rescue—Maybe

Johannes Gutenberg University, Mainz, F.R.G.

F. E. Brinckman

May 11, 1979

Biotransformations and Speciation of Organoarsenical s and Qrganotins

in Aquatic Systems

Swiss Federal Institute for Water Resources and Water Pollution

Control (EAWAG), Zurich, Switzerland

F. E. Brinckman

August 13, 1979

Biotransformations and Speciation of Organoarsenical s and Qrganotins

in Aquatic Systems

University of Stockholm, Stockholm, Sweden

F. E. Brinckman

August 20, 1979

Opto-Gal vanic Spectroscopy: A New Look at Atoms and Molecules

University of Maryland, College Park, Maryland

P. K. Schenck

February 1979

Vapor Pressure Measurements of Potassium Over K2 0-Si02 Solution

by a Knudsen Effusion Mass Spectrometric Method

10th Materials Research Symposium on Character!' zati on of High

Temperature Vapors and Gases, NBS

E. R. Plante

September 18-22, 1978

Optogalvanic Spectroscopy: A New Look at Atoms and Molecules

10th Materials Research Symposium on Characterization of High

Temperature Vapors and Gases, NBS

K. C. Smyth, P. K. Schenck, W. G. Mallard, ard J. C. Travis.

September 18-22, 1978

A Comparison of Optical Flame Temperature Measurements: Na Line

Reversal, Rotational and Vibrational Raman, and OH Absorption

Spectroscopy

10th Materials Research Symposium on Characteri zati on of High

Temperature Vapors and Gases, NBS

M. Drake, L. Grabner, and J. W. Hastie

September 18*22, 1978

73
Transpiration Mass Spectrometry of High Temperature Vapors

10th Materials Research Symposium on Characterization of High

Temperature Vapors and Gases, NBS

0. Bonne! 1 and J. W. Hastie

September 18-22, 1978

Raman Spectroscopy in High Temperature Chemistry

10th Materials Research Symposium on Characterization of High

Temperature Vapors and Gases, NBS

M. C. Drake and G. M. Rosenblatt

September 18-22, 1978

Slag and Metal Oxide Vaporization in Reactive Atmospheres

International Colloquim— Use of Refractory Oxides for High

Temperature Energy Sources, Toronto, Canada

J. W. Hastie

July 15-20, 1979

Molecular Chemistry of Inhibited Combustion Systems

AR0--Engine Combustion Workshop, Madison, Wisconsin

J. W. Hastie

July 22-24, 1979

Synthesis, Structure and Electrical Properties of Doped

Polyacetylene

International Conference on Transport Processes in Macromolecul ar

Systems, Konigstein/Ts. , Germany

C. K. Chiang

September 6, 1978

Doped Polyacetylene: A Semiconducting and Metallic Organic Polymer

American Physics Society, Chicago, Illinois

C. K. Chiang

March 19, 1979

Impedance Measurements in Solid Electrolytes

DOE/EPRI National Fuel Cell Seminar, Bethesda, Maryland

A. D. Franklin

June 26, 1979

Publ i cations

The Role of Noncrystalline Films in Passivation and Breakdown of

Passivation

A. G. Revesz and J. Kruger in Passivity of Metals, R. P. Frankenthal

and J. Kruger, Editors

El ectrochemical Society, Princeton, New Jersey, pp. 137-155 (1978)

74
Photopotentials on Copper and Copper Alloy Electrodes

U. Bertocci

J. Electrochemical Society, 1 25 , 1598 (1978)

The Protection of Steel Piles by Selected Coatings in a Natural Sea

Water Environment

E. Escalante and W. P. Iverson

Proceedings of the Offshore Technology Conference (1978)

The Protection of Steel Piles by Nonmetal lie Coatings in Sea Water

E. Escalante and W. P. Iverson

Materials Performance, 1 7

,

10, pp. 9-15 (October 1978)

Chemistry of Corrosion—New Approaches

J. Kruger, from Materials and National Policy (ACS), Compiled and

Edited by the Dept, of Chemistry and Public Affairs, pp. 75-82

(Fall 1978)

Slow Strain Rate Stress Corrosion Testing of Metals in Gaseous

Atmospheres at Elevated Temperatures

G. M. Ugiansky and C. E. Johnson

Proceedings of ASTM Symposium: Stress Corrosion Cracking—The

Slow Strain Rate Technique, ASTM STP 665 (January 1979)

Slow Strain Rate Stress Corrosion Testing of Aluminum Alloys

G. M. Ugiansky and C. E. Johnson

Proceedings of ASTM Symposium: Stress Corrosion Cracki ng--The

Slow Strain Rate Technique, ASTM STP 665 (January 1979)

Proceedings of the Workshop on Alternatives for Cadmium Electroplating

in Metal Finishing, October 4-6, 1977

Elbert Dage, Edward Dyckman, William Isler, and Fielding Ogburn,

Editors (March 1979)

Ultra Black Coatings for High Absorbance of Solar Energy

C. E. Johnson

Proceedings of Silver Jubilee Meeting, Institute of Environmental

Sciences, pp. 12-13 (April 1979)

Field Ion Microscopy

A. J. Melmed and J. Smit

Journal of Physics and Scientific Instruments, J_2, 335 (1979)

Immersion Plating on Aluminum

D. S. Lashmore

Proceedings of the 66th Annual Technical Conference, AES, p. L2

(June 24, 1979)

Corrosion Induced by an Alternating Voltage. A Comparison Between

Theoretical Predictions and Experimental Results

U. Bertocci and J. L. Mullen

Paper N. 242, NACE Corrosion ‘79, Atlanta, Georgia (1979)

75
Laboratory Corrosion Studies on Tinned Copper Concentric Neutral

Wi res

U. Bertocci and J. L. Mullen

Materials Performance, ]_8, (6) 24 (1979)

AC Induced Corrosion. The Effect of an Alternating Voltage on Electrodes under Charge-Transfer Control

U. Bertocci

Corrosion, 35.» 211 (1979)

Protection of Steel Piles by Selected Coatings in a Natural Sea

Water Environment

E. Escalante and W. P. Iverson

J. of Petroleum Technology, 3J_, p. 1035 (1979)

Fundamentals of Corrosion of Metallic Implants

J. Kruger

ASTM STP

in press

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

£. Escalante, U. Bertocci, and J. L. Mullen

Materials Performance

in press

The Location Effect on the Corrosion 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

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

in press

76
The Role of Noncrystall ine Films in Passivation and Breakdown of

Passivation

A. G. Revesz and J. Kruger

Proceedings of the 7th International Congress on Metallic Corrosion

in press

An Electrochemical Study of an Al-Zn-Mg Alloy

G. M. Ugiansky, J. Kruger and R. W. Staehle

Proceedings of the 7th International Congress on Metallic Corrosion

in press

Thickness of Gold Coatings Measured with a Calibrated SEM

F. Ogburn and D. Ballard

Plating and Surface Finishing of The J. of the Electroplaters'

Society

in press

Mtissbauer Spectroscopy of Polycrystalline Steel Fibers

D. S. Lashmore, L. J. Swartzendruber , and L. H. Bennett

Applied Physics Letters

in press

Corrosion Enhancement Due to Large Voltage Modulations. Frequency

Analysis of the Response of Electrodes Under Charge-Transfer

U. Bertocci and J. L. Mullen

Proceedings of the ASTM Symposium on "Progress in Electrochemical

Corrosion Testing"

in press

Underground Corrosion

E. Escalante

"Corrosion and The Building Industry", National Association of

Corrosion Engineers Publication

in press

Thin Zinc Film on Aluminum

D. S. Lashmore

J. Electrochemical Society

in press

Soils and Underground Corrosion

E. Escalante

Proceedings of Liberty Bell Corrosion Course 1979

in press

The Morphology of Immersion Coatings on A1

D. S. Lashmore

Plating and Surface Finishing

in press

77
Detection and Analysis of Electrochemical Noise for Corrosion Study

U. Bertocci

Proceedings of the 7th International Congress on Metallic Corrosion,

Rio de Janeiro (1978)

in press

Influence of Environmental Parameters on Transmethylation

Between Aquated Metal Ions

K. L. Jewett, F. E. Brinckman, and J. M. Bel lama

ACS Symposium Series, No. 82 in Qrqanometal s and Qrqanometal 1 oids

Occurrence and Fate i n the Envi ronment , paper 11 , 158-187 (1978)

Speciation of Metals in Used Oils: Recent Progress and

Environmental Implications of Organoleads in Used Crankcase Oils

F. E. Brinckman

Proceedings of the Second Conference on Measurements and Standards

for Recycled Oil-II, NBS SP 556, November 29-30, 1977 (1979)

Graphite Furnace Atomic Absorption Spectrophotometers (GFAA) as Automated Element-Specific Detectors for High-Pressure Liquid

Chromatography (HPLC): The Determination of Arseni te, Arsenate,

Methyl arsonic Acid, and Di methyl arsinic Acid

F. E. Brinckman, K. L. Jewett, W. P. Iverson, K. J. Irgolic,

K. C. Ehrhardt, arvd R. A. Stockton

J. Chromatography

in press

Application of a Graphite Furnace Atomic Absorption Detector

Automatically Coupled to HPLC for Speciation of Metal -Contai ni ng

Macromolecules

E. J. Parks, F. E. Brinckman, and W. R. Blair

J. Chromatography

in press

Absorption Spectra of Metal Oxides Using Opto-Gal vanic Spectroscopy

P. K. Schenck, W. G. Mallard, J. C. Travis, and K. C. Smyth

J. Chem. Phys., 69, 5147-5150 (1978)

Trend in Structure and Vibrational Frequencies of MX 2 and MX 2 High Temperature Halide Vapors

M. C. Drake and G. M. Rosenblatt

J. Electrochemical Society, ]_26, 1387 (August 1979)

An Examination of Five Preferred Orientation Functions

W. S. Horton

Carbon, 17, 153-155 (1979)

Effect of Selective Laser Excitation on the Ionization of Atomic

Species in Flames

J. C. Travis, P. K. Schenck, G. C. Turk, and W. G. Mallard

Anal. Chem., 5T_, No. 9, 1516-1520 (1979)

78
Vapor Pressure Measurements of Potassium Over K2 0-Si0 2 Solution

by a Knudsen Effusion Mass Spectrometric Method

E. R. Plante

Proceedings of the 10th Materials Research Symposium on Character!' zation

of High Temperature Vapors and Gases, NBS, September 18-22, 1978

NBS SP 561 (September 1979}

Optogalvanic Spectroscopy: A New Look at Atoms and Molecules

K. C. Smyth* P. K. Schenck, W. G. Mallard, and J. C. Travis

Proceedings of the 10th Materials Research Symposium on Character!' zation

of High Temperature Vapors and Gases, NBS, September 18-22, 1978

NBS SP 561 (September 1979)

A Comparison of Optical Flame Temperature Measurements: Na Line

Reversal, Rotational and Vibrational Raman, and OH Absorption

Spectroscopy

M. Drake, L. Grabner, and J. W. Hastie

Proceedings of the 10th Materials Research Symposium on Characterization

of High Temperature Vapors and Gases, NBS, September 18-22, 1978

NBS SP 561 (September 1979),

Transpi rati on Mass Spectrometry of High Temperature Vapors

D- Bonne! 1 and J. W. Hastie

Proceedings of the 10th Materials Research Symposium on Characteri zati on of High Temperature Vapors and Gases, NBS, September 18-22, 1978

NBS SP 561 (.September 19791

Raman Spectroscopy in High Temperature Chemistry

M. C. Drake and G. M. Rosenblatt

Proceedings of the 10th Materials Research Symposium on Characteri zation

of High Temperature Vapors and Gases, NBS, September 18-22, 1978

NBS SP 561 (September 1979)

Spectroscopy and Photophysics of the CF 2/( B 2 -X System

D. S. King, P. K. Schenck, and J. C. Stephenson

J. Mol. Spec,

in press

Improved Sensitivity for Laser Enhanced Ionization Spectrometry

In Flames Using Stepwise Excitation

G. C. Turk, W. G. Mallard, P. K. Schenck, and K. C. Smyth

Ana! . Chem.

in press

Nondestructive Analysis of Laser Fusion Microsphere Targets Using

Rotational Raman Spectroscopy

M. C. Drake and G. J. Rosasco

J. Applied Physics

in press

79
Spectroscopic Technique for the Measurement of Residual Stress in

Sintered A1 2 0 3

L. H. Grabner

J. Applied Physics

in press

Internal Friction and Sodium Transport in Beta Alumina

J. H. Simmons, A. D. Franklin, K. F. Young, and M. Linzer

J. Amer. Ceramic Soc.

in press

Slow Transient Phenomenon in Y-Doped Ce0 2

C. K. Chiang, A. L. Dragoo, and A. 0. Franklin

Proceedings of International Conference on Fast Ion Transport

in Solids, Lake Geneva, Wisconsin, May 21-25, 1979

in press

Preparation of Pt-Fe Alloy Foils by Electrodeposition

A. D. Franklin and J. Epp

J. Electrochemical Society

in press

Test Procedures for Recycled Oil Used as Burner Fuel

J. J. Comeford

Proceedings of the Second Conference on Measurements and Standards

for Recycled Oil-II, NBS SP 556, November 29-30, 1977 (1979)

Establishing Substantial Equivalency for Motor Oils

J. J. Comeford

Proceedings of the Second Conference on Measurments and Standards

for Recycled Oil-II, NBS SP 556, November 29-30, 1977 (1979)

A Novel Bimetallic Sulfur Cluster. Crystal and Molecular Structure

of a Dimer of Bis[methyldiphenylphosphinesi 1 ver]tetrathiotungsten,

[ (^ 6 ^ 5 ) 2 PCH 3 ] 4 Ag4W2 Ss

J. K. Stalick, A. R. Siedle, A. D. Mighell, and C. R. Hubbard

J. of the American Chemical Society, 2903-2907 (1979)

Transition Metal Derivatives of the Tetracyanoqui nodimethandi ide Ion,

TCNQ 2 A. R. Siedle, G. A. Candela, and T. F. Finnegan

Inorganica Chimica Acta, 35, 125-130 (1979)

Crystal Structure of (Benzotriazol ato)thal 1 i um(I) and Its Relation

With the Mechanism of Corrosion Inhibition by Benzotri azol

e

J. Reedijk, G. Roelofsen, A. R. Siedle. and A. L. Spek

Inorganic Chemistry, 18, No. 7, 1947-1951 (1979)

80
Metals in Oil: Occurrence and Significance for Reuse of Spent

Automotive Lubricating Oils

T. D. Coyle and A. R. Siedle

Proceedings of the Second Conference on Measurements and Standards

for Recycled Oil-II, NBS SP 556, November 29-30, 1977 (1979)

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

W. F. Gerhold, Member

Structures

American Petroleum Institute and American Society for

Materi al

s

Joint Committee on Static Petroleum Measurement,

Group on Water and Sediment

J. J. Comeford, Member

American Society for Testing and Materials

Testing and

Worki ng

A05: Metallic Coated Iron and

W. F. Gerhold, Chairman,

Steel Products

Member:

A05.14

A05.15

A05.16

Sheet Tests

Wire Tests

Hardware Tests

Chai rman

B08: Electrodeposited Metallic

Fi ni shes

F. Ogburn, Member:

B08.01

Coatings and Related

B08. 03:

B08. 04

BOS. 05

B08. 06

B08. 08

B08. 09

B08. 10

B08. 11

Terminology, Editing, Public

Relations and Metrication

WG.05: Metrication, Chairman

Decorative Copper, Nickel, Chromium,

and Nickel -Chromi um Coatings

WG: Electrodeposited and Electroless

Black Coatings for Solar Use

Zinc and Cadmium Coatings

Coatings of Tin, Lead, and Their Alloys

Anodic and Chemical Conversion

Coatings on Aluminum and Magnesium

Al 1 oys

Engineering Coatings

Precious Metal Coatings

General Test Methods

WG.01: Measurement of Coating

Thickness, Chairman

Government SDeci f i cati ons , Chairman

81
C5:

D2:

El 3:

E34:

G01

:

Manufactured Carbon and Graphite Products

W. S. Horton, Member:

C5.02: Nomenclature

C5.05: Nuclear Applications

Petroleum Products and Lubricants

S. M. Hsu, Member

C. Ku, Member

R. Gates, Member

J. J. Comeford, Member:

Advisory Committee

E-I: Burner Fuel Oils

IV: Hydrocarbon Analysis

IV-F: Absorption Spectroscopy Methods

P-Recycled Petroleum Products and Lubricants,

Vi ce-chai rman P-Advisory, Vice-Chairman

P-I: Automotive Lubricants

P— II: Used Oils and Base Stocks

P— III: Fuel Oils, Chairman

P-IV: Industrial and Hydraulic Oils

P-VI: Miscellaneous Products

P- VII : Editorial

Molecular Spectroscopy

R. B. Johannesen, Member:

El 3. 07: Nuclear Magnetic Resonance,

Chai rman

Occupational Health and Safety Aspects of Materials,

Physical and Biological Agents

F. E. Brinckman, Member:

E34.10: Definitions and Nomenclature,

Co-Chai rman

Corrosion of Metals

U. Bertocci , Member:

G01 .11: Electrochemical Measurements in

Corrosion Testing

E. Escalante, Member:

GO 1.10: Corrosion in Soils, Chairman

W. F. Gerhold, Member

G01.01

G01 .04

G01 .05

G01 .06

G01 .98:

Research

Atmospheric Corrosion

Laboratory Corrosion Tests

Stress Corrosion Cracking and

Corrosion Fatigue

Advisory Committee on Exposure

Test Facilities

82
W. P. Iverson, Member:

GO 1.10: Corrosion in Soils

TG: Electrochemical Polarization

Techniques for Measurement of

Corrosion Rates in Soils,

Chai rman

J. Kruger, Member:

G01.02: Nomenclature

G01.90: Executive Committee

GO 1.99: Standing Committee on Liaison, Chairman

Controlled Release Society (International)

Publications Committee

F. E. Brinckman, 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. Bertocci , Member

Technical Affairs Committee

J. Kruger, Member

Federation of Materials Societies

Board of Trustees

J. Kruger, Trustee for Electrochemical Society, Past President

Gordon Research Conferences

Counci 1 J. Kruger, Member

International Standards Organization

TC107: Metallic and Other Non-organic Coatings

F. Ogburn, Delegate:

1: Terminology, Delegate

2: Methods of Inspection and Coordination of

Test Methods, Delegate

3: El ectrodeposi ted Coatings and Related

Finishes, Delegate

7: Corrosion Tests, Delegate

TC156: Corrosion of Metals

J. Kruger, Delegate:

1: Terminology, Delegate
International Union

Commission II: of Pure and Applied Chemistry

Inorganic Chemistry Division

T. D. Coyle, Associate Member:

Commission II— 2: Nomenclature

W. S. Horton, Member

Division Committee

Commission II— 3: High Temperatures

and Refractory

Materials, Associate

Member

Characterization and

Terminology of

Carbon, Vice Chai rman|

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 Society of

Canada

Joint Committee of Atomic and Molecular Physical Data

R. B. Johannesen, Member:

NMR Subcommittee

National Association of Corrosion Engineers

Education Committee

J. Kruger, Member

Publications Committee

J. Kruger, Member:

Subcommittee on New Publications

J. Kruger, Chairman

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

National Research Council

Committee on High Temperature Science and Technology

J. W. Hastie, Member

84
Panel on Small Research Projects in Materials Sciences

A. D. Franklin, Chairman

Committee on Accelerated Corrosion of Copper-Nickel Piping,

National Materials Advisory Board

l). Bertocci , Member

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

U. Bertocci, Consultant

Committee on Recommendations for U. S. Army Basic Scientific

Research

J. Kruger, Member:

Corrosion, Surfaces, and Interfaces Section,

Chai rman

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

Seminar Summary

Current Understanding of Stress Corrosion Cracking

E. N. Pugh

University of Illinois, Urbana, Illinois

June 27, 1978

Microstructure of El ectrodeposi ted Metals

R. Weil

Stevens Institute of Technology, Hoboken, New Jersey

September 26, 1978

Electrodeposition Research in the Communications Industry

D. R. Turner

Bell Telephone Laboratories, Murray Hill, New Jersey

November 1, 1978

35
Cryptate Complexes of Lanthanide(III) Elements

0. Gansow

Michigan State University, Lansing, Michigan

January 25, 1979

Electrochemical Corrosion Research at the Rockwell Science Center

F. Mansfeld

Rockwell International Science Center, Thousand Oaks, California

February 9, 1979

The Morphology of Immersion Deposited Zinc on Aluminum

D. S. Lashmore

NBS Research Associate, Aluminum Association

February 16, 1979

Organotin Chemistry-New Compounds and Applications. The Existence

of the Tin-Tin Double Bond

J. J. Zuckerman

University of Oklahoma, Norman, Oklahoma

February 27, 1979

Electrochemical and Mechanical Aspects of Stress Corrosion Crack

Propagation in Face-Centered Cubic Metals

J. C. Scully

University of Leeds, Leeds, England

March 19, 1979

The Role of H2 S and Sulfide Films on the Hydrogen Entry into

Iron and Steel in Sour Environment

T. Murata

Nippon Steel Company, Japan

March 19, 1979

The IGSCC of Austenitic Stainless Steels in High Temperature Water

Containing 8 ppm 0 2

H. Hanninen

Technical Research Center of Finland

March 20, 1979

Studies of Early European Iron Slags

G. Sperl

Erich Schmid Institute, Loeben, Austria

April 18, 1979

Preparation and Characterization of Thin Oxygen-Ion Conducting Ceramics

A. L. Dragoo

NBS, Division 561

April 27, 1979

86
Conservation Treatment of Oil Paintings and the Detection of

Forgeries

C. H. 01 i

n

Great Falls, Virginia

June 13, 1979

High Resolution NMR of Solids

J. Riemer

California Institute of Technology, Pasadena, California

June 29, 1979

External Recognition

Richard Merton Visiting Professor

Johannes Gutenberg University

Mainz, Federal Republic of Germany

April -May; June- September , 1979

F. E. Brinckman

George Kimball Burgess Memorial Lecture for the year 1979

Washington Chapter

American Society of Metals

June 1979

J. Kruger

Books

Organometals and Qrganometal 1 oi ds: Occurrence and Fate in the

Envi ronment

Edited by F. E. Brinckman and J. M. Bel lama

American Chemical Society Symposium Series No. 82

Washington, D. C. , 448 pages

1978

Passivity of Metals

Edited by R. P. Frankenthal and J. Kruger

Electrochemical Society, Princeton, New Jersey, 1072 pages

1978

Characterization of High Temperature Vapors and Gases

Edited by J. W. Hastie

Proceedings of the 10th Materials Research Symposium, NBS

,

September 18-22, 1979

in press

Special Reports

A Bibliography on the Corrosion and Protection of Steel in Concrete

E. Escalante and S. Ito

NBS Special Publication 550 (August 1979)

87
Stress Corrosion Behavior of 7049-T76510, -T73510, and -T7351]

Aluminum Alloy Extrusions

B. T. Sanderson and W. F. Gerhold

NBSIR 78-1587 (Report to Naval Air Systems Command) (1979)

A Review of Techniques for Measuring the Corrosion of Metals in

Concrete

E. Escalante

NBSIR, (Report to the Federal Highway Administration)

in press

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, (Report to the Office of Naval Research)

in press

Recycled Oil Program: Phase 1—Test Procedures for Recycled Oil

Used as Burner Fuel

D. A. Becker and J. J. Comeford

NBSIR 78-1453 (1979)

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 FY 78, and the same number

were produced during FY 79.

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 carbon13 line positions (eight lines). It is expected that the initial

stock will consist of 200 NMR tubes.

88
Patents

Enrichment of Chlorine Isotopes by Visible Laser Techniques

J. J. Ritter

May 24, 1977

U. S. Patent 4,025,406

Ultra-Black Coating Due to Surface Morphology

C. E. Johnson

NBS Case No. 1760

Filed April 1979

Apparatus for Galvanic Detection of Optical Absorptions

R. B. Green, R. A. Keller, G. G. Luther, P. K. Schenck, and

J. C. Travis

April 10, 1979

U. S. Patent 4,148,586

Sponsored Conferences

Corrosion General Session, Corrosion Division

Electrochemical Society, Boston, Massachusetts

May 8, 1979

J. Kruger

Progress in Electrochemical Corrosion Testing

ASTM, San Francisco, California

May 21-24, 1979

U. Bertocci

Corrosion General Session, Corrosion Division

Electrochemical Society, Pittsburgh, Pennsylvania

October 17, 1979

J. Kruger

Underground Corrosion Symposium

ASTM, Williamsburg, Virginia

November 26-27, 1979

E. Escalante

Early Pyrotechnol ogy

Smithsonian Institution and NBS, Washington, DC

April 19-20, 1979

A. D. Franklin and J. Qlin

89
FRACTURE AND DEFORMATION DIVISION

90
PAGE

NO(S)gjf_

MISSING
PAGE

NO(S)2i

MISSING
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

The Division research emphasizes mechanical property and fracture

mechanics theory and experiment. Fracture and deformation mechanisms

are explored. New test standards are developed and characterized.

Techniques of microscopy and nondestructive inspection are used in

failure analyses and evaluation of fracture mechanisms, deformation,

wear, oxidation, and effects of defects. Research relates predominantly

to metals and alloys, ceramics, and composites.

During this past year, the NBS-Boulder fracture mechanics and

mechanical property group has been integrated into the Fracture and

Deformation Division. The Boulder-based group complements the Division,

since it has specialized in low-temperature mechanical properties and,

recently, in elastic-plastic fracture mechanics. This combination en- compasses most of the NBS mechanical property research and all of the

NBS fracture mechanics activities. Research at both high and low temperature extremes is represented. A core group in fracture mechanics

will provide the means to grow in that area in the near future.

The strengths of the new Division can be generalized by the following categories: deformation and fracture of ceramics, failure analysis,

low-temperature mechanical properties and fracture, development of test

standards, fracture control, and effects of weld defects. Research this

past year related to these five Division specialties is briefly summarized

here. Studies of ceramics include creep rupture at elevated temperatures;

erosive wear and strength degradation from particle impact; high-temperature,

high-pressure compressive strengths of castable refractories ; flexural

and compressive strength characteri zation of geothermal cements; effects

of microstructure on stress-corrosion cracking of aluminum oxide for

prosthetic applications; and electron microscopy studies. Special

failure analysis tasks this past year?have included the second Silver

Memorial Bridge failure (Pt. Pleasant, West Virginia), a seamless welded

steel pressure vessel that ruptured while being filled with natural gas,

and railroad wheel and tank car failures. Low- temperature research

included an assessment of carbon and nitrogen additions to the strength

and toughness of austenitic stainless steels at liquid helium temperatures

(4 K), the tensile, shear, and compressive characterizati on of fiberglass/

epoxy composites at low temperatures , the characterization of the temperature dependence of the flow strength of austenitic stainless steels

from 4 to ICO K, and further development of welding alloys and processes

for the use of stainless steels in cryogenic applications. Research has

progressed on J-integral, precracked Charpy impact, and on assistance to

ASTM in the establishment of standard test procedures and specimen

parameters. Research to establish alternative allowable defect size

92
standards, based on fitness-for-service, previously conducted for the

trans-Alaska oil pipeline, is now progressing for the Alaska Natural Gas

Transportation System and includes pipe and weldment material properties, elastic-plastic-model development and verification, and nondestructive inspection to measure defect length and depth.

Our technical outputs are directed toward a broad range of government and industrial users. The emphasis on fusion, magnetohydrodynamics

(MHD), coal gasification, and geothermal energy by the Department of

Energy has led to 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 magnets used in MHD, characterization of castable refractories

at high temperatures and pressures, the development of an i_n si tu evaluation test to assess metal susceptibility to high-temperature, highpressure environmentally assisted metal cracking, and property characterization of geothermal cements.

Transportation-related research includes the establishment of 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, and numerous structural metal fracture

analyses.

The research for the Department of Defense is diverse with the objectives to assist the Navy in the eventual up-grading of their fracture

control plans, to identify material limitations in ultrasensitive gyroscopes used in inertial guidance systems, study of the applicability of

proof testing to nitride and carbide ceramics that have potential use in

gas turbine engines, to conduct erosion and wear experiments of ceramics

to attempt to reduce machining costs, to examine the low-temperature

material properties related to the use of superconducting motors and

generators for ship propulsion, and to assist the Air Force in using

advanced composites in light-weight superconducting magnet airborne

power packages.

The Division manages as well as conducts research for three programs: (1) Evaluation of Pipeline Girth Welds for the Department of

Transportation, (2) Structural Materials Research at Low Temperatures

for Superconducting Magnets for Fusion Applications for the Department

of Energy, and (3) Cryogenic Materials and Welds for the US/USSR Science

and Technology Program of the National Science Foundation. In these

programs, the col laboration of industries and universities is beneficial, and research subcontracts are issued to contributing laboratories.

Considerable emphasis is placed on technology transfer. We cur- rently have two books in preparation: Materials at Low Temperatures

(containing tutorial chapters on mechanical and physical properties,

materials, and special considerations for use of materials in cryogenic

applications) and a "Summary of Fracture Mechanics Concepts" (by R. deWit

in collaboration with G. R. Irwin, University of Maryland). Workshops

93
on Materials at Cryogenic Temperatures are held annually at Vail,

Colorado, in collaboration with the Department of Energy. This year, in

collaboration with various coordinating groups, four Workshops related

to ceramics were held at NBS-Gaithersburg. The Division plays a major

role in the establishment (1975) and operation of the International

Cryogenic Materials Conference, which holds yearly international conferences, that are growing rapidly. It organized and leads a group of six

other industrial concerns and universities in the US/USSR Science and

Technology Joint Exchange Program on Electrometallurgy. The Failure

Information Center is maintained to provide materials information on failures in coal gasification and conversion plants; we are collaborating with the Department of Energy and Battel le Memorial Institute in

this effort.

Because of the NBS Materials Durability Initiative, in this next

year our Division will have the opportunity to emphasize new research

thrusts. The need for extension of workmanship codes to fitness-forservice alternatives for reduction of repair welds, for assessment of

specific defects in critical structures, for fracture control plans of

critical structures, and for lifetime estimates of structural integrity

has placed increasing emphasis on elastic-plastic fracture mechanics.

Elastic-plastic fracture mechanics models and methodologies are needed,

instead of the more traditional elastic mechanics approach, since es- sentially all structural alloys for critical applications are selected

to ensure against crack instability preceding plastic deformation.

Therefore, research concentrating on test methodologies, model development and verification, effects of defects and subcritical crack growth,

all' related to elastic-plastic or fully plastic conditions, will be

i nitiated.

Secondly, although the Division has studied the high-temperature

aspects of ceramic durability, we have not placed emphasis on high

temperature or time-dependent studies of metals. Such research is

timely, since new energy conversion systems, plasma containment systems,

and nuclear systems all have current serious material selection and

durability problems associated with the understanding and character!* za- tion of 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 insight to assist in high-temperature design and material

selection.

These new directions, plus the addition of the staff from Boulder,

have led our Division to modify and exDand our primary research tasks

for the next year. This past year our two tasks have been:

1 . Fracture and Deformation Science for Durability and Reliability

of Metallic Structures and

2 . Fracture and Deformation Science for Durability and Reliability

of Ceramic Structures

94
To replace these two tasks, we will establish three new tasks for the

Fracture and Deformation Division:

1. Fracture Mechanisms and Analyses

2. Durability of Ceramics and Composites

3. Elastic-Plastic Fracture Mechanics

Research within our Division will be discussed under Subtasks of these

three tasks. It must be considered, however, that these objectives have

been established just recently and that the research for the past year

was directed primarily toward the objectives established for the earlier

tasks. Tasks 1 and 3 will receive greater emphasis from the opportunities under the Materials Durability Initiative; included as part of the

introduction to each task will be a brief discussion of this expected

new research.

FRACTURE MECHANISMS AND ANALYSES

Fundamental understanding of crack-tip processes is vital to an understanding of fracture and to the development of long-term failure

prediction techniques for structural materials. The influences of

atomic structure and chemical reactions at the crack tip are demonstrated from atomistic models of fracture in a solid, but these influences remain to be confirmed quantitatively by experimental studies

of subcritical crack growth and environmental effects. Ductile processes in the high-stress region of the crack tip 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; the influences

of microstructure, impurity content and segregation, processing history,

and environment combine to influence competitive fracture mechanisms,

such as subcritical crack growth, cavity nucleation and growth, and

grain boundary sliding.

Failure analysis studies perform a valuable service for those

government agencies that have no facilities and indicate that research

is required for safe performance of structural materials. By using

modern metal 1 ographic , 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.

Because of the Materials Durability Initiative, there will be increased emphasis on high-temperature fracture processes and mechanisms.

Crack-tip theory coupled with high-temperature tensile, creep, and

fatigue research will be directed toward increasing our understanding of

the fracture of metals under time-dependent conditions.

95
The Fracture Mechanisms and Analyses Task is subdivided into four

subtasks: Fracture Theory, Plastic Deformation of Metals, Failure

Deformation Center, and Failure Avoidance Services. Each of these is

summarized below.

Fracture Theory

E. R. Fuller, R. M. Thomson, and S- W. Freiman

Lattice theories of fracture were extended to include the effect of

corrosive environment for the simple one-dimensional model of a crack.

The solid in which the crack is enclosed consists of two one-dimensional

chains of atoms that form a border for the crack and the projected crack

plane. The two chains are bonded in the projected crack plane by linear

springs; the atoms within each chain are bonded by bendable springs. At

the tip of the crack is a nonlinear spring that can also react with the

corrosive environment, which is composed of diatomic molecules. Predictions of the stress dependence of the activation energy for crack

notion indicate a power law dependence whose exponent varies from 3/2 to

2 depending on the form of the atomic bonds of the solid. General

conclusions are: (1) chemical activity accentuates and extends the

intrinsic slow crack-growth phenomenon because of the surface absorption

activation barrier, and (2) the ''chemical" and "mechanical" contributions to the activation energy for slow crack growth are not separable.

Tensile experiments are now being conducted on silicon to attempt

to correlate chemical activity, mechanical stress, and crack-tip opening.

Optimum selection of environment and temperature is necessary to ensure

chemical absorption yet to prevent crack-tip blunting from dislocation

processes.

Plastic Deformation of Metals

B. W. Christ and R. S. Polvani

Tensile microcreep in various metals and alloys is measured.

Current focus is on instrument-grade beryllium. The overall goal of__

this work is two-fold: (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 is a joint effort of two groups

within N8S and the Draper Laboratory, Cambridge, Massachusetts.

Microcreep testing of instrument grade beryllium has been carried

out at about 63 °C (145 °F), and temperature control is held to ± 0.005 °C

(0 1 01 °F) on a testing system designed to detect strains in the range of

10’ 7

. A major finding is the phenomenon of microcreep exhaustion, i.e.,

loss of the ability for continued microcreep. This phenomenon is attributed to the exhaustion of glide dislocations through an as-yet-tobe-identified microstrain hardening process. The potential of microcreep exhaustion for promoting ultradimensional stability in gyroscope

structural components will be explored.

96
The building of a second testing system designed like the first is

nearing completion. A third testing system designed to detect strains

in the range of 10‘3 has been completed. Testing for zero-appliedstress dimensional stability of instrument-grade beryllium is being

undertaken. A fourth testing system to obtain biaxial microcreep data

is being designed. A review paper surveying the micromechanical properties of beryllium is nearing completion.

Failure Information Center

R. C. Dobbyn and 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, es- pecially failures, of materials and components used in coal conversion

environments. It provides an integrated materials properties data base

for materials of construction to aid the coal conversion industry in the

design, construction, and operation of plants converting coal to alternate energy forms, including MHD power generation. Finally, it collects

and evaluates the appropriate information, maintains suitable computer

files for ready retrieval, and disseminates the data in convenient form

to the 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 OoE voluntary failure reporting program. Informational 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 assisted plant operators in problem solving.

Several draft reports have been assembled and other dissemination

schemes are being explored. One output mechanism that has proved successful is the failure experiences feature in DoE

r s Materials and Components Newsletter , in which NBS and Battel 1 e-Col umbus cooperate.

Requests for additional details are received regularly from Newsletter

readers

.

At present, the Center produces sets of abstracts covering all re- ported incident and sorted according to material, component type,

failure mode, and conversion process, or any combination of these. The

abstracts are intensive summaries constructed from the source document

and contain all reported data.

97
During the past year, the Failure Information Center has completed

a detailed study of the performance of materials used in the Conoco

Lignite Gasification Pilot Plant (C0 2 Acceptor Process). The study is

based on the information contained in plant operating records and is not

limited to reported failures. A complete report is now available. In

addition, the Center responded to 68 requests for information and supplied over 2800 reports and abstracts summarizing the details of

in-service materials performance.

Failure Avoidance Services

B. W. Christ, C. G. Interrante, J. G.. Early, T. R. Shives, and

G. E. Hicho

Failure avoidance services are provided to other government agencies and to other NBS Divisions. Services provided include diagnostic

failure analysis, mechanical testing, metal lographic analysis, and

metallurgical consultation. Sponsoring agencies include the Office of

Pipeline Safety Regulations and other branches of the Department of

Transportation, the National Transportation Safety Board, the Department

of Defense, the Consumer Product Safety Commission, the 3ureau of Engraving and Printing, and the Department of Agriculture. These sponsoring agencies have responsibilities in matters of public safety,

productivity, national defense, and the promotion of effective and

responsive regulations. When structural failures occur or when metallurgical problems arise, NBS responds immediately to help the sponsoring

agency. NBS provides a prompt and objective assessment of the cause of

failure based on metallurgical evaluation and nondestructive examination

of the material and a structural analysis based on mechanical properties

measurements and fracture mechanics concepts.

This past year, 15 reports were issued to sponsoring agencies; they

are listed, later in this report. These are reports of structural failures that occurred in pressure vessels, aircraft components, railroad

tank cars, gas distribution lines, amusement park rides, seat belts,

fuel pumps, printing plates, bicycle parts, and building construction

materials. Highlights are listed below:

A seamless steel pressure vessel in natural gas service ruptured

violently via hydrogen embrittlement arising from 600 ppm H 2 S

impurity in the gas reacting with extremely hard microzones (HRC 40)

in the steel.

A year-old steel gas distribution line rupture was due to stress

corrosi on.

A bicycle crank fracture was due to brittle zones that developed

during improper heat treatment.

98
DURABILITY OF CERAMICS AND COMPOSITES

The durability of ceramic and composite materials is studied to

provide assurance of the reliability of these materials in structural

applications. Ceramic materials are used in many critical applications

where properties, such as chemical resistance to corrosive environments,

mechanical resistance to erosion and wear, and physical resistance to

temperature extremes, are required. Ceramics, such as glasses, refractory concretes, geothermal cements, porcelains, and high density ceramics,

are used in commercial applications, such as containers for nuclear

waste disposal , linings for geothermal wells, components for hightemperature gas turbines and heat exchangers, thread guides and wear

surfaces for paper and clothing manufacture, 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. In many applications resistance to mechanical abuse is crucial

in determining the successful use of ceramic materials. Because they

are brittle, structural ceramics are usually overdesigned to satisfy

engineering requirements or are not used, even though they have other

outstanding properties. By investigating the fracture and deformation

properties of these materials, many difficulties associated with their

brittle behavior may be overcome.

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, light weight, and 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, enhanced productivity, improved product safety, and enhanced

U.S. technological innovative capabilities. The key to effective industrial utilization of composite materials lies in an improvement of

our understanding of wear-out and fracture mechanisms in these materials. By investigating the mechanical strength and fracture behavior

of a variety of composite materials (ceramic/ceramic, ceramic/ metal,

ceramic/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.

The Fracture and Deformation Division program on ceramics and

composites can be divided into the following parts: the development of

basic fracture and fracture mechanics information on structural materials,

development of new engineering data for design purposes, the investigation of processes that result in erosive and abrasive wear of ceramics

and composites, and an investigation of the microstructure of composites

and ceramics through the use of light and electron microscopy. Experimental techniques developed by the Division permit us to conduct mea- surements on the mechanical properties of composites and ceramics over a wide range of experimental conditions: in vacuum at temperatures to

99
2700 °C, in corrosive environments at temperatures that range from room

temperature to 1000 °C, in air at temperatures that range from room

temperature to 1500 °C, and at cryogenic temperatures as low as -259 °C.

This range of experimental capabilities within the Division is unique.

Fundamentals of Fracture

S. W. Freiman, B.. J. Hockey, S. M. Wiederhorn, and E. R. Fuller

The effects of proof testing on the strength of materials were investigated. A theoretical study was conducted to evaluate the effect of

single-region and multi -region crack propagation on strength of components

after the proof test. In this study, two single-region Wei bull -type

strength distributions were studied: one with a slope of m at high

cumulative failure probability levels; the other with a slope of R-2 at

low failure probability levels.* Truncation of the strength distribution always occurs as the result of proof testing; the truncation

strength depends on the rate of unloading. In contrast to these results

for single-region crack propagation, multi-region crack propagation

results in a more complicated strength distribution after proof testing.

Bimodal strength distributions occur as a consequence of region-IItype crack growth (i.e., R-0). Theoretical results confirm experimental

findings that proof tests must be conducted at rapid unloading rates and

with good environmental control to be effective. Experimental investigations are currently underway to check the predictions of this theoretical model of proof testing.

Secondly, a new analytical technique, electron scanning for chemical analysis (ESCA), was applied to analyze the type of chemical re- actions that occur during the stress corrosion of ceramic materials.

This, coupled with other techniques, will enable analysis of chemical

species that form on freshly fractured surfaces that are exposed to

active environments. During the past year, the surface analysis system,

which includes ESCA, SIMS, and Auger spectroscopy, arrived and was put

into operation. The thin-film deposition system, which will be used to

make test specimens, is being attached to the surface analysis system so fresh uncontaminated surfaces of ceramic material can be analyzed when

the equipment is fully operational. To study the effect of stress on the chemical reactions, a specimen holder that can stress the thin film

has been designed and built. The holder is held in a shuttle that goes

between the film deposition chamber and the analysis chamber. A thin

film of ceramic is formed on a substrate, which is then stressed using a micromanipulator, reacted with an environment and transferred into the

analysis chamber for examination. To date, thin films of aluminum oxide

have been deposited on aluminum using an electron beam deposition system

that is part of the apparatus. In the coming year, we hope to use the

*m is the shape factor of the Weibull Strength distribution before

proof testing; R is the exponent of the stress. intensity factor, Kj,

assuming that the crack velocity can be expressed as a power function

of the stress intensity factor: v = AKI

n

.

100
apparatus for chemical analysis of stressed ceramics and glasses. This

project is being conducted jointly between the Fracture and Deformation

Division (S. W. Freiman). and the Ceramics, Glass, and Solid State Science

Division (D. M. Sanders).

New Techniques for Obtaining Fracture and Deformation Information

E. R. Fuller, S. W. Freiman, S. M. Wiederhorn, R. J. Fields, and

N. J. Tighe

Fracture mechanics provides engineers with new design techniques

for estimating the total allowable lifetime under load. Fracture mechanics

techniques can be used in this application 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 elevated temperatures is creep and creep cracking. By

characterizi ng 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 of structural materials.

To improve our ability to collect useful data for lifetime predictions, a new type of loading apparatus was developed for dead-weight

loading of structural ceramic materials. The technique involves the use

of pneumatic loading as a substitute for the dead-weight loading usually

used for constant-load experiments. The pneumatic system has several

advantages over the dead-weight system. It is inexpensive and compact;

a number of them can be used simultaneously for experimental purposes

without requiring a great deal of space for operations. Their advantage

of space efficiency was used in the construction of a high-temperature

fracture mechanics facility, which was designed so that three loading

fixtures were operated within each furnace. A similar facility is now under construction for evaluating the creep resistance of refractory

materials for regenerative heat exchangers in large MHD facilities. The

pneumatic test facilities have the further advantage that when the

static load test has been completed, it is possible to load the specimens pneumatically so the strength can be measured. A pneumatic loading

facility is also being 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 that are intended for use as prosthetic devices.

Often our ability to assess materials in new environments depends

as much on the way we view the engineering information available on a material as it does on the information itself. In the past year, a new 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. The experimentally controllable parameters, I,

and i, are plotted as ordinate and abscissa related by contours of

constant material response, i.e., crack velocity. This sort of map

emphasizes changes in a materials fracture resistance as either the

101
temperature or the stress intensity factor change. In general, the

resistance of a material to slow cracking or fracture depends upon the

temperature and the load level. Any change in mechanism of cracking or fracture will manifest itself as a change in dependence on these two

controlling parameters. On the map, such a change would be indicated by an abrupt change in slope of the constant velocity contour lines. The

loci of such slope changes define boundaries between different mechanisms of slow crack growth or fast fracture. The boundaries may be sharp

or diffuse, but within a set of boundaries exists a region in which one

mechanism of slow crack growth or fracture is dominant. This new type

of map has been applied to high-temperature fracture data on hot-pressed

silicon nitride, providing a clear picture of the regions over which

each mechanism of crack growth is dominant. During the coming year, it

is intended to apply this new mapping procedure to other ceramic and

metal materials to see if mechanisms for crack growth can also be

clearly represented for these materials.

Engineering Evaluation of Ceramics

E- R. Fuller, N. J. Tighe, S. M. Wiederhorn, S. W. Freiman,

D. E. Roberts, C. L. McDaniel, and R. F. Krause, Jr.

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: castable

refractories for coal gasification application, 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.

Work on castable refractories is being conducted because of the intended use of three refractories in coal gasification applications,

where strength must be maintained under severe environmental conditions.

The objectives of the project are to characterize the mechanical properties (strength, erosion resistance, and fracture toughness) that relate

to the structural integrity of refractory concretes intended for use in

coal conversion systems, to correlate these mechanical properties with

microstructural changes that are induced by the reactive environment and

to develop equipment and test procedures to assess the reliability and

durability of castable refractories . Our major accomplishment last year

was the completion of a high-pressure, high-temperature mechanical test

machine that will be capable of measuring strength in gasification

environments at extreme temperatures (100 °C) and pressures (7 MPa,

1000 psi ) for these environments. The unit has been. operated at design

conditions. Initial experiments were conducted in steam at temperatures

as high as 1000 °C on both a low (56%) aluminum oxide refractory and a high (94%) aluminum oxide refractory. Results of these initial experiments are consistent with results from previous experiments in which the

strength was tested after high-temperature, high-pressure exposure.

Results indicate that the lower purity (_and cheaper) 56% aluminum oxide

102
refractory is superior for coal gasification reactor linings. As noted

in- earlier reports on the Department of Energy, this resu.lt should contribute to substantial savings in the construction costs of gasifiers

through the use of the less expensive refractory.

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 will provide 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 the Department of Energy. The program is divided into several tasks

aimed at establishing the physical properties of cements after they have

been exposed to simulated geothermal environments. Physical properties

to be measured include flexural and compressive strengths, strengths of

cement pipe interfaces, and cement permeability at elevated pressures

and temperatures. The equipment for this study has been designed and is

being built. Proposed procedures for these tests have been drafted and

submitted to an American Petroleum Institute Task Group for evaluation.

These procedures have been approved tentatively with a final vote expected in the fall of 1979.

At the request of the Department of Energy, a special series of

screening tests was conducted on geothermal cements to evaluate the

performance of a special group of cements. The structural stability of

the cements was evaluated after exposure to water at temperatures of ^ 200 °C and pressures of a. 20 MPA (% 2800 psi ) for extended intervals of

time. Among the cements that were tested were candidates that had been

proposed for use in a remedial cementing operation of a hot-dry-rock

well at Los Alamos Scientific Laboratory. A series of shear-bond

strength tests was also conducted to examine the influence of thermal

cycling on the interfacial bond between a steel rod and the cement.

because ceramic materials offer the potential for significant

increase in operating temperatures and efficiency for gas turbine

engines, silicon nitride is being considered by the Department of

Defense and the Department of Energy for application in heat engines.

Work at NBS on the subject of proof testing as a method of ensuring the

reliability of this material at high temperatures is being conducted

under the auspices of the Department of Energy. The objective of this

study is to determine if the strength distribution of population of test

specimens can be truncated by proof testing. Earlier studies for the

Department of Defense showed that truncation as a practical technique

was viable at room temperature and for rather large cracks at high

temperatures . In addition, there is an upper limit to the proof test

load that can be used to achieve reliability without destroying too many

specimens. During the past year, this work was extended to include

reaction-sintered silicon nitride and hot-pressed silicon nitride doped

with yttrium oxide. Work on the reaction-bonded silicon nitride indicates that proof testing as a means of ensuring component reliability

will be applicable to this material. Results at room temperature and at

103
1200 °C show that, regardless of test conditions, the strength distribution of the reaction-bonded silicon nitride is truncated by proof

testing. This conclusion is based on several hundred strength tests

conducted on this material after exposure to 1200 °C at load for periods

as long as 1000 hours. We conclude that, when subjected to stress at

1200 °C, the material will either fail upon loading or will support its

load indefinitely at elevated temperatures . This conclusion is consistent with the fact that subcritical crack growth, as determined by

fracture mechanics techniques, does not occur in this material at

1200 °C. At room temperature, subcritical crack growth does occur, but

in a predictable manner, so that the framework of fracture mechanics can

be used to predict lifetime. These conclusions do not seem to be applicable to yttria-doped, hot-pressed silicon nitride, which can fail

unpredictably when subjected to high temperatures (1200 °C) under sustained load conditions. Flaw generation and subcritical crack growth

seem to be a real problem with the hot-pressed material. Work is continuing on this material to determine the causes of failure.

Another new and interesting application of ceramic materials is in

the field of medicine. Certain types of ceramic materials (aluminum

oxide, glass ceramics) are useful as structural components of prosthetic

devices because they are biologically inert to the body environment and

are relatively strong compared with bone. As a consequence, these

materials are being introduced into the body in several applications:

total hip replacements, anchors for artificial teeth, and artificial

knee joints. In these applications, ceramic materials will have to

sustain structural loads for periods that may last for forty years or longer. Given the tendency for ceramic materials to undergo stress

corrosion cracking owing 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

Fracture and Deformation Division has been conducting a study to determine the effect of microstructure on stress-corrosion cracking of

aluminum oxide.

During the past year, one of the major tasks has been to assemble

the test rigs to perform long-term delayed failure studies on biomaterials. This setup has been nearly completed. It consists of 10 pneumatically loaded test rigs. The specimens will be held in tanks through

which the selected liquid environment will flow using a peristaltic

pump. We are in the process of assembling a mi crocomputer system that

will monitor the stresses on the test specimens and from which the

failure times can be determined. Data will be displayed on a video

screen in the laboratory.

Initial data have been obtained in air on 3C to 50 specimens of the

Friedericksfeld A1 2 0 3

. The crack growth parameters calculated from

these data agreed with those obtained at the University of Florida under

the same conditions.

104
Considerable discussions have been carried out with Dr. Larry

Hench of the University of Florida and Dr. Jerry Klawitter of Tulane

University regarding a joint research program with NBS. The result of

discussions with Dr. Klawitter is a proposal summary that has been

submitted to FDA. In this study Tulane University would perform the in_

vivo studies on stressed ceramic specimens. NBS would conduct the

accompanying mechanical property experiments before and after implantation.

Discussions with Dr. Klawitter have also been held regarding the

development of an ASTM standard on the strength and mechanical testing

requirements of A1 2 0 3 for implants. The writing of a draft standard is

planned within the coming year.

A new project for the coming year will evaluate the mechanical

properties of alkali halides to be used as scintillation material for

the NASA Gamma Ray Observatory. Data on mechanical properties are

needed by NASA to aid in the efficient design of the support housings

for the scintillation materials. Materials to be studied include Nal

and Csl, both of which will be used in the Observatory. The type of

information needed includes compressive and flexural strength measurements for the Nal and the Csl, creep measurements for the Csl, and

fracture toughness and static fatigue measurements for the Nal. Equipment is currently being designed and constructed to perform the required

mechanical tests. The work is expected to be completed by the end of

the 1980 fiscal year.

A second new project for the coming year will be directed toward

the development of screening tests to assess the performance and ex- pected lifetime of ceramic capacitors for defense applications. These

studies will be conducted on multilayered ceramic capacitors that are currently being used in a number of critical military applications,

among which is the guidance system for the Trident missile. The need

for reliability in these systems is obvious, so mechanical or electrical

reliability of these capacitors should be ensured to technically achievable levels. Studies on this project will involve the use of ultrasonic

signals combined with sophisticated computer analysis techniques as

a means of deleting delaminations and cracks in capacitor parts. In

support of this screening development, studies will be concluded to

characterize the mi crostructure of ceramic capacitors and to establish

the susceptibility of the ceramic material in the capacitor to strength

degradation resulting from internal stresses and subcritical crack

growth. This research is a joint effort between Divisions 562 and 564

to provide technical assistance to the Navy to improve the reliability

of chip capacitors for defense applications.

The final project on our program of engineering evaluation of

ceramic materials is concerned with refractory materials 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

105
% 1500 °C. Temperatures of this level require the operation of regenerative heaters at temperatures as high as 1650 °C, which requires re- fractory 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 in excess of 1500 °C. Consequently, there is a need to collect such data if regenerative heaters are to operate suc- cessfully in the necessary temperature range. The objective of this

research project is to obtain 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 proposed service temperature of 1400 to 1650 °C. To date, equipment has been designed for multiple creep experiments on candidate

materials at temperatures as high as 1650 °C in air. The equipment uses

the pneumatic loading fixtures described above in this report. When

completed, the test facility will be capable of measuring creep on 12

specimens simultaneously. All components for the test facility are

currently being ordered or constructed at NBS. An existing dead-weight

loading apparatus was modified to obtain preliminary data on candidate

materials and to eliminate any potential problems that might arise in

the course of the study.

Friction and Wear of Ceramics

S. M. Wiederhorn, B. J. Hockey, and H. Johnson

Friction and wear are important phenomena that determine the cost

and reliability of precision-ground ceramic parts. Since machining

often accounts for 90% of the cost of these parts, a considerable re- duction in costs may be achieved through an understanding of 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 the strength

of these materials. To achieve these ends, this project has been initiated to study the friction, wear, and erosion resistance of commercially important ceramic materials.

In an extension of work conducted last year on sharp particles, ' impact data (SiC grains against glass) were collected to evaluate the

effect of impact angle on contact-induced strength degradation. These

studies were conducted to determine if impact at oblique angles leads to

local damage that is greater than that predicted by elastic-plastic

strength degradation theories developed to explain strength degradation

at normal impact. Tf enhancement of damage does not occur, then ex- isting analyses can be used as a conservative basis for design. It was also felt that such a study might throw light on the damage mechanisms

themselves and so add to our understanding of similar angular effects in

erosion phenomena.

106
Strength degradation tests were run on crown glass discs using

150 um SiC particles at a velocity of n, 94 m/s. Various angles of ex- posure were used in the study with at least 10 specimens per angle..

Strength results from ring-on-ring tests indicate an increase of

strength as the impact angle becomes more oblique. However, the

strength increase is less than that predicted from current theories,

assuming that only the normal component of the velocities is effective

in providing the driving force for crack formation. Plastic stresses

arising from the shear component of velocity appear to contribute to

crack formation and thus to strength degradation. However, the degradation appears to be small relative to that occurring at normal impact,

so the elastic-plastic theory of strength degradation proposed earlier

can be applied to obtain a conservative estimate of strength.

The above observations suggest that a shear component of velocity

contributes to strength degradation. These observations are consistent

with earlier observations on the erosive wear of ceramic materials,

which indicate a contribution to erosion is a result of oblique impact

of erosive particles. Shear stresses that occur during oblique impact

apparently enhance the intensity of the plastic zone that results in

crack formation and, therefore, increase the size of the cracks that are

formed at impact.

Our data base for the erosion of brittle materials was expanded by

obtaining erosion data on silicon (room temperature, 500 °C, 1000 °C),

fused silica (room temperature, 500 °C) soda-lime silicate glass

(500 °C and 600 °C) and sapphire (room temperature, 500 °C and 1000 °C).

These data were combined with erosion data on aluminum oxide and hotpressed silicon nitride obtained in earlier studies to show the dominant

effect of fracture toughness (K^) and hardness (H) on the erosion rate.

Resistance to erosion was found to be largest for materials for which

the ratio of the toughness to the hardness, K^/H, was high. Therefore,

K^/H appears to be an important parameter for evaluating the erosion

resistance of ceramic materials. In the year to come, these data will

be used to summarize the effect of material properties, such as K, and

H, on the resistance of materials to erosive wear. Comparisons between

data obtained from these studies and theoretical expressions for the

erosion rate will be made to determine the applicability of the erosion

theories to brittle materials.

Microstructural Analysis of Ceramics

B. J. Hockey and N. J. Tighe

The objective of this subtask is to investigate the relation between structural and mechanical properties of ceramic materials. This

subtask develops and applies techniques of high resolution transmission

and scanning electron microscopy to study deformation and fracture and

wear processes in hard materials.

107
Earlier transmission electron microscopy studies on impact damage

were extended this year by the use of scanning electron microscopy.

This technique was used to evaluate the role of microstructure in determining the extent and type of impact damage that occurs during erosion. Temperature and particle velocity were used as parameters in

studies on glass, silicon, sapphire, 30 ym grain-size alumina, 3 ym

grain-size alumina, and hot-pressed silicon nitride. As indicated by the size of lateral cracks formed during impact, brittle behavior was enhanced as the fracture toughness (K Tr ) decreased. For

it

i example, Si 3 N 4 , which has a fracture toughness of ^ 6 MPa-m , showed

very little chipping or crack formation associated with the damage at

the- contact area. In contrast, glass and silicon, which have relatively

1 12

low values of toughness (-v 0-8 and 0.7 MPa-m , respectively), exhibited

well -developed crack structures, with both lateral and median vents

extending far beyond the immediate impact site. The type and extent of

damage appeared to correlate with erosion rates measured on these materials (discussed below), confirming the importance of high fracture

toughness to good erosion resistance.

Perhaps the most interesting observation made in these microstructural studies was on glass impacted at room temperature with 150 urn SiC

particles at a velocity of n, 94 m/s. Under these conditions, the temperature elevation was so high that pools of molten glass formed at the

impact site. At oblique angles of impact, molten glass attached itself

to the impacting particles and glass fibers were pulled from the surface

of the glass. Simple theoretical estimates indicate glass temperatures

in excess of 900 °C. A more detailed model, which was developed to

explain thermal effects during erosion, confirmed these high-temperature

estimates.

The effect of ambient temperature on erosion damage was investigated by comparing surface damage occurring at room temperature with

that occurring at elevated temperatures (500 °C, 600 °C, and 680 °C for

glass; 500 °C for silicon; 500 °C and 1000 °C for A1 2 0 3 and Si 3 N 4 )

.

Despite the higher ductility of these materials at elevated temperatures, the damage during impact was very similar to that observed at

room temperature. However, qualitative differences between room temperature and elevated-temperature erosion were observed. In glass,

lateral cracks did not extend as far at 500 °C and 600 °C as they did at

room temperature. Furthermore, plastic deformation at the contact site

was enhanced at high temperatures. These differences in appearance

of the contact site account for the observed decrease in the erosion

rate of glass at elevated temperatures . For the crystalline materials

studied (A1 2 0 3 , Si 3 N 4 , Si), differences in appearance of the contact

site occurred, but were not as obvious as those observed for the glass,

which probably accounts for the fact that the erosion rate at elevated

temperatures was virtually identical to that obtained at room temperature.

108
Engineering Evaluation of Composites

M. B. Kasen and R. E. Schramm

This effort began in 1973 with a comprehensive literature review of

the existing state of knowledge on the effect of cryogenic temperatures

on the mechanical and thermal properties of composite materials. An

increasing use of composite materials in high-technology cryogenic areas

had created the need for a reliable data base on low-modulus (glassreinforced) and high-modulus (graphite, boron, Kevlar) polymer-matrix

composite laminates. These reviews, published in Cryogenics , June and

September 1975, provided the background for establishing test programs.

Data available in 1975 indicated that all of these composite types were

viable structural materials for cryogenic use. But the temperature

dependence of the mechanical properties and the values for the properties showed a large scatter. It was apparent that this variability

reflected inadequate test methodology and relatively poorly characterized materials.

The NBS testing programs were initially funded by ARPA as part of a program to acquire data relevant to the construction of superconducting

machinery. A continuation of these studies was funded by the U.S.

Air Force Aero Propulsion Laboratory (AFAPL) , Wright-Patterson AFB,

Ohio. The object of the latter program was to provide composite property data relevant to construction of lightweight, airborne superconducting power packages based on either generator or magnetohydrodynamic

designs.

These studies required development of improved testing techniques

capable of producing valid tensile, compression, and shear data from all

types of composite materials from 295 K to 4 K. Information derived

during this phase was communicated to Committee D -30 of ASTM, which is

primarily responsible for establishing standard methods of composite

testing. M. B. Kasen of the Fracture and Deformation Division is a member of this Committee. Participation was timely, since such standards were almost nonexistent.

Development of test methods proceeded concomitantly with the ac- quisition of systematic data on the cryogenic temperature effect. The

NBS objective was to characterize the major mechanical properties of

state-of-the-art boron-, glass-, graphite- and Kevlar-reinforced epoxy

products from 295 K to 4 K. Twin outputs of the program were the establishment of the first systematic data base reaching to liquid helium

temperature and an assessment of the need to develop special epoxy resin

formulations for cryogenic use.

Key properties are those required for prediction of crossply laminate performance using macromechanical composite theory developed in

the aerospace industry. Required data are longitudinal and transverse

uniaxial strengths, moduli, and Poisson's ratios, plus in-plane shear

109
strength and modulus. These data have been acquired for epoxy-matrix

laminates reinforced with 0.14mm (5. 6-mil). boron, S-glass, Kevlar 49,

and Types AS, HM-S, and GY-70 graphite fibers. A 0.14 mm (5. 6-mil)

boron-reinforced aluminum was also characterized. The data have thus

far failed to define performance regions, therefore the development of

special composite formulations is necessary for cryogenic use. But the

possibility that such a development might be justified under cyclic

loading conditions remains, to be investigated.

A second major direction in the program reflected the need to use large quantities of low-cost, high-pressure industrial laminates as structural support and electrical insulation in large superconducting

magnets for magnetic fusion energy and magnetohydrodynamic power generation in the consumer area. The commercial hi gh-pressure industrial

glass-epoxy laminates produced under NEMA (National Electrical Manufacturer's Association). designations G-10 and G-ll are normally selected

for this application. But such materials display large property variability at cryogenic temperatures. Therefore NBS has cooperated with

NEMA and the U.S. laminating industry to establish a uniform specification for cryogenic grades of such laminates. These products, designated G-10CR and G-11CR, are now in commercial production. Their mechanical, electrical, and thermal properties have been extensively characterized at NBS-Boulder with the participation of the Massachusetts

Institute of Technology, Los Alamos Scientific Laboratory, Westi nghouse,

and General Electric. The performance of these materials under neutron

and gamma radiation at 4 K is under assessment at Oak Ridge National

Laboratory.

The composite program during the past year included characterization of the performance of graphite-epoxy laminates at cryogenic

temperatures . Additionally, we served as a consultant to the USAF on composite materials selection for the prototype advanced-composite

superconducting generators being designed for the Air Force by General

Electric, and the lightweight magnetohydrodynamic power systems being

designed by General Dynamics/Convai r in association with the Magnet

Corporation of America. Characterization of the mechanical properties

of the cryogenic-grade G-10CR and G- 1 ICR materials also continued.

ELASTIC-PLASTIC FRACTURE MECHANICS

Safety and durability are primary considerations in the design and

construction of engineering structures. Sophisticated methods to assess

structural safety and durability have been developed on the basis of

linear elastic fracture mechanics. These analytical methods are applicable to the high-strength alloys used for aerospace vehicles and to

the heavy section steels used for nuclear pressure vessels. Unfortunately, the methods of linear elastic fracture mechanics are not applicable to a wide range of metal structures, including bridges, pressure

110
vessels, ships, offshore structures, and pipelines. In these applications, the materials of construction (steels and aluminum alloys are typical) exhibit substantial plasticity (nonlinear behavior) before

fracture. Consequently, linear elastic methods are not applicable and

the assessments of structural safety and durability are based on em- pirical methods and extensive prior experience. Although current

methods generally 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 consists of five subtasks:

1. J-integral evaluations are used to characterize the fracture

resistance of structural alloys and to determine the driving

force for fracture under elastic-plastic conditions.

Z. Current fracture control procedures are being reviewed and we

are contributing to the development of test standards for

improved procedures.

3.. The significance of defects, particularly in weldments, are being evaluated on the basis of plastic strain cycling tests

and analytical studies.

4. 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 evaluated.

5. Elastic deformation phenomena are being studied to contribute

to our understanding of the fundamental basis of strength.

Fracture Control

H. I. McHenry, R. deWit, D. T. Read, and B. W. Christ

Many engineering practices contribute to the prevention of fracture

in metal structures. Elastic-plastic fracture mechanics is a technology

that can contribute to development of improved practices based on con- sideration of material toughness, operating stress levels, and probable

defect sizes. As discussed elsewhere in this report, work is underway

in the Fracture and Deformation Division relating to improved measures

of material toughness, improved means of fracture mechanics analysis, and

significance of defects. Other fracture control activities are discussed here: a survey of fracture control practices used by American

industry, a tutorial report on fracture mechanics concepts, and participation in the standardization of fracture test methods.

Ill
A survey of fracture control practices used by American industry

was conducted for the U.S. Navy. The specific objectives of the resulting report were: (1) to review the elements of fracture control

and to prepare a detailed summary of industrial practice relative to

each element, and (2) to identify fracture control concepts potentially

transferable to the Navy. Twelve classes of structures were reviewed

including ships, offshore structures, bridges, pressure vessels, aircraft, piping, cryogenic tankage, electrical power generation equipment,

space vehicles, and pipelines.

A tutorial report on fracture mechanics is being prepared in collaboration with Professor G. R. Irwin of the University of Maryland.

This report includes both linear elastic and elastic-plastic fracture

mechanics. Fracture and subcritical crack growth owing to fatigue and

stress corrosion are discussed. A summary of fracture mechanics concepts has been completed.

Minimum toughness requirements are frequently included in material

procurement specifications. Standard test methods are essential to

ensure the buyer and seller of the material that the toughness meets

specified requirements. The Fracture and Deformation Division is contributing to the standardization of test methods for evaluating the

fracture toughness using the J-integral, the J-resistance curve, and the

crack opening displacement methods. Division activities include membership in the responsible ASTM committees and participation in round-robin

testing programs.

J-Inteqral Evaluations

D. T. Read, R. L. Tobler, T. A. Whipple, and H. I. McHenry

The J-integral is a characterization 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^, which is a measure of the plane strain fracture toughness. The Fracture and Deformation Division is conducting research using the J-integral 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-strai n characteri sties on the J-integral value.

During the past year, we have made substantial improvements in our

test facilities, experimental methods, and analytical capabilities. A

1 MN capacity servohydraul ic fatigue test machine has been procured and

installed. It is being used to apply a uniform strain field to tensile

panels with flaws that are small compared with the overall panel size.

A minicomputer has been procured and computer- i nteracti ve J-integral

test procedures have been developed. These advanced test procedures are

now being used to evaluate the fracture toughness of stainless steel

alloys and weldments for cryogenic service. A finite element computer

112
code, for elastic-plastic fracture mechanics analysis, developed by the

Navy, has been obtained and is operational on the NBS computer. The

two-dimensional analysis code features crack-tip-singularity elements

that enable simplified grids for calculating the J-integral and thereby

substantially reduce the computer time requirements for elastic-plastic

analysis. The computer analyses are being used to study the influence

of strain hardening and geometric configuration on the plastic strain

field in tensile panels with through- thickness cracks.

A major new experimental effort has been started to measure directly the J-contour integral on tensile panels under elastic-plastic

loading conditions. Single-edge-notch tensile panels are instrumented

with strain gauges along the vertical boundaries and displacement gauges

along the horizontal boundaries. Gauge signals are recorded by a com- puter and the strain energy density is calculated on the basis of the

stress-strain characteristics of the test material. The rotational

contribution to J is computed from displacement signals from LVDT

transducers mounted along the top and bottom of the specimen. Tests to

date have confirmed the feasibility of the method and have provided a positive check on the finite element analysis predictions. This represents a start on the goal of relating the J-integral to the applied

strain and flaw size for a variety of geometric configurations and

structural alloys. Measurements of this type are being conducted for

the Navy to establish a J-integral design curve and for the Office of

Pipeline Safety Regulation to develop an analytical model for prediction

of critical flaw sizes in pipeline girthwelds.

Significance of Defects

R. deWit, J. H. Smith, D. T. Read, M. B. Kasen, J. G. Early, and

H. I. McHenry

The Fracture and Deformation Division is conducting programs for

the Navy and for the Office of Pipeline Safety Regulation regarding the

significance of defects, particularly in welded structures. Weld

quality standards usually stipulate allowable defect sizes on the basis

of workmanship considerations, i.e. , what level of quality can generally

be achieved by a qualified welder using the proper welding materials and

procedures under reasonable working conditions. These quality levels

may differ significantly from the quality required to ensure structural

integrity.

In the Navy programs, a J-integral design curve is being developed

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 relationship

between the J-integral fracture toughness, the applied strain, and the

defect size.

. Initial tests, currently in progress, involve tensile

panels of ship steel with edge cracks. Future work will progress to

center cracks, surface cracks, and cracks in welds. The influence of

113
residual stress on the design curve will be assessed using wide plate

tests currently being fabricated by the Navy. The program is being

conducted in collaboration with the Naval Ship Research and Development

Center and Professor S. T. Rolfe of the University of Kansas.

The program for the Office of Pipeline Safety Regulation is being

conducted to establish weld quality requirements for the Alaska Natural

Gas Transportation System. Initial studies involve analytical modeling

of the significance of defects using methods comparable to those used

for the trans-Alaska pipeline assessment conducted previously. Future

work will involve J- integral studies comparable to the Navy program and

verification testing on small-scale and full-scale pipe specimens. In

addition to the fracture studies, fatigue tests are being conducted to

evaluate the effect of plastic-strain cycling on nonplanar defects, such

as porosity and slag. Load-controlled fatigue tests are planned to

determine the influence of simulated service loading on the growth of

planar defects, such as lack of fusions and lack of penetration.

Low-Temperature Properties

R. P. Reed, H. I. McHenry, D. T. Read, R. L. Tobler, and R. E. Schramm

The increased use of natural gas, usually shipped and transported

in liquefied form (LNG), has led to materials research on economical

structural alloys and insulation materials. Such research has been

necessary to satisfy regulations based on fracture control plans for LNG

ships and stringent safety requirements for LNG storage sites inspired

by the potentially dangerous consequences of LNG. Our research, sponsored by the Gas Research Institute and the Maritime Administration, now

focuses on development of improved low-temperature LNG ship hull steel

plate, and characterization of the mechanical properties of concrete and

foam insulations used by the LNG industry. To develop economical steel

plate more tolerant to high heat input welding techniques, major ship

plate producers and LNG ship builders were assembled and combined with

NBS in a joint program. Better steels have been identified and characterized for use by the shipbuilding industry.

A major developing technology is the use of superconducti ng magnets

for energy applications. High magnetic fields are required for fusion

plasma and MHD plasma confinement and guidance. Superconducting ma- chinery, under prototype development, provides the potential for better

performance coupled with lighter weight and reduced space requi rements.

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 liquid-helium temperature (4 K) for times up to 20 years.

Such emphasis on liquid helium design and material use has led to

rather large national materials programs, sponsored by DARPA and DoE

and managed by our Division. These programs have produced a lowtemperature materials handbook; mechanical, thermal, electrical, and

114
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,

Teledyne-McKay, Alcoa, Armco, and Bel four-Stulen. Major research em- phasis 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.

Research highlights this past year include the following: Additions of 0.2% nitrogen to an iron-chromium-nickel austenitic stainless

steel (AISI 304) achieve yield strength increases of a factor of five at

liquid-helium temperatures. Since nitrogen alloying is inexpensive and

the preliminary J-integral measurements indicate sufficient toughness,

additional research will proceed to characterize high-nitrogen stainless

steels at 4 K.

The temperature dependence of the flow strength of austenitic

stainless steels has been measured and analytically characterized.

Anomalous regions of decreases of strength with decreasing temperature

have been identified and correlation with the martensitic transformation

is progressing.

A correlation between low-temperature fracture toughness and ferrite concentration in stainless steel weldments has been obtained;

higher ferrite concentrations reduce the low- temperature toughness.

Our Division plays a major role in world-wide low temperature

materials research. It organized the International Cryogenic Materials

Conferences (ICMC), held annually in various countries (average number

of papers = 100), and the ICMC current Board Chairman is from our Division. A series of bound volumes, Cryogenic Materials Series, contains

the proceedings of these conferences. The Division, collaborating with

the Thermophysical Properties Division (NEL) personnel, is in the final

stages of completing a tutorial book, Materials at Low Temperatures.

Division personnel organized and led a group of U.S. scientists (from

Alcoa, Armco, Westinghouse, University of California, University of

Illinois, Rensselaer Polytechnic Institute) collaborating with the USSR

under the US/USSR Science and Technology Exchange Program, Electrometallurgy Working Group. The exchange research emphasizes development

of a ferritic weld metal and processes for use with iron-nickel alloys,

development of a ferrite-free, microfissure-free austenitic filler

metal, and characterization of low-temperature flow strengths of

austenitic Fe-Cr-Ni alloys.

115
Elastic Deformation Phenomena

H. M.. Ledbetter

A solid's elastic constants provide fundamental information 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 elastic-property data, (2) experiment,

and (3) theory.

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. Also identified are suggested areas for further study. From

both university laboratories and industrial 1 aboratori es , we have re- ceived considerable encouragement for more studies of these kinds.

Our experimental studies deal with metals, alloys, composites, and

polymers; with single crystals and with polycrystals. Notable recent

studies include the paramagnetic spin-glass transition in manganese

stainless steels, the omega-phase effects in niobium-titanium alloys,

and precise measurement of the complete set of elastic constants of* a boron-aluminum composite and their reconciliation with theory. Laserinduced bulk and Rayleigh waves have been used to study composite superconducting wires. Because superconducting wires are used in critical

design applications such a magnets, these studies are important, especially in terms of rul e-of-mixture predictions and in the compositional

variation of the wire's physical properties, especially those that are design parameters.

Our theoretical efforts focus on three principal problems: (1) re- lationships between elastic constants and other physical properties,

particularly the Debye characteri stic 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, collaborating with T. Suzuki,

using pseudopotentials, we have recently calculated the elastic con- stants of the alkali metals and related these to their phase-transition

behavior. An exciting new concept for 1 ow-temperature solid-state

nucleation of the new phase is emerging from these calculations. Basically,

the traditional surface-energy-term approach, which fails to predict

reaction rates, is replaced by a 1 attice-deformati on-energy term that

might predict them.

116
Test Methods and Standards

B. W. Christ, J. G. Early, C. G. Interrante, G. E. Hicho, and

J. H. Smith

The development of test methods and standards often follows closely

the- failure analysis tasks carried out for other agencies. In addition,

ASTM and ASME often call on NBS expertise for assistance in formulating

test methods and standards. Staff members of the Fracture and Deformation Division are contributing to the following work.

Hydrogen Embrittlement : This project carries out research to

establish guidelines to be used for developing standard fracture mechanics test methods for hydrogen embrittlement of steel exposed to aqueous

media. Emphasis is on pressure vessel steels and structural steels of

moderate strength. These steels are of commercial significance in the

petrochemical industry and the transportation industry. Ties have been

established with the Pressure Vessel Research Committee of the Welding

Research Council.

ASTM Subcommittee E24. 03-Alternative Fracture Test Methods : Chai rmanship of this Subcommittee involves fostering fracture test

methods which differ from ASTM Standard E399, which is a plane strain

fracture toughness test. Alternative methods apply to high toughness

structural metals and include the Pre-cracked Charpy and Dynamic Tear

Test Methods. Applications of the Equivalent Energy Method of data

analysis are being looked into by this Subcommittee.

ASTM Subcommittee E24.Q5 Fracture Terminology : Chairmanship of

this subcommittee involves developing standard terminology for Fracture

Toughness Testing. Numerous definitions have been developed and balloted already.

ASTM Committee E38-Resource Recovery : Membership on this Committee

involves contributing to the development of standards. Two standards

have been prepared: "Standard Methods of Test for Municipal Ferrous

Scrap," and "Standard Specifications for Municipal Ferrous Scrap." The

data base for the former method was developed in the following technical

paper: "Determination of Combustible Material in Ferrous Scrap Recovered from Refuse," by J. G. Early (to appear in The Journal of

Resource Recovery )

.

ASTM Task Group E28. 04. 03-Verification of Alignment : Chairmanship

of this task group involves developing a standard method for verifying

alignment under tensile loading. This method applies to tensile, stress

rupture, creep, uniaxial fatigue and microstrain testing. A draft

method is ready for subcommittee ballot.

U.S, Coast Guard-Equivalence of Codes and Standards : This task was recently undertaken with the sponsorship of the U.S. Coast Guard-Department of Transportation. The objective is to make recommendations to the

117
sponsor concerning the equivalency to U.S. specifications of structural

materials made to foreign specifications. The German DIN specification

and the Japanese JIS specification are being examined first.

United Nations Specification For Compressed Gas Containers : This

task is being performed for the Materials Transportation Bureau-U.S.

Department of Transportation. An international specification for seamless and welded steel containers has been prepared.

Other Division Activities

Sponsored Conferences

NBS-DoE Workshop on Materials at Low Temperatures

Kiandra/Tal isman Lodge, Vail, Colorado

October 1978

Basic Science Division Meeting of the American Ceramic Society

National Bureau of Standards, Washington, D.C.

November 1978

Science of Ceramic Machining and Surface Finishing, II

National Bureau of Standards, Washington, D.C.

November 1978

Ninth Meeting of Interagency Coordiantion Group for Application of

Ceramics to Heat Engines

National Bureau of Standards, Washington, D.C.

November 1978

ONR Workshop on Erosion of Materials

National Bureau of Standards, Washington, D.C.

June 1979

International Cryogenic Materials Conference (ICMC)

University of Wisconsin, Madison, Wisconsin

August 1979

Invited Talks

Summary of Fracture Mechanics Concepts

Oak Ridge National Laboratories, Oak Ridge, Tennessee

R. deWit

Operational Experiences in Nuclear Power Plants, Regulation and

Research

Panel for Special Symposium on In-Service Data Reporting and Analysis

American Society of Mechanical Engineers, San Francisco, California

R. C. Dobbyn

December 1978

118
The Performance of Materials in Advanced Coal Conversion Pilot

Plants

Oak Ridge National Laboratory, Oak Ridge, Tennessee

R. C. Oobbyn

May 1979

How Should We Handle the Subjective Component of In-Service Data

Reporting and Analysis

Materials and Fabrication Committee, PVP Division

American Society of Mechanical Engineers, San Antonio, Texas

R. C. Dobbyn

August 1979

Some Effects of Geometry on the High Temperature Fracture Notched

Components

Oak Ridge National Laboratory, Oak Ridge, Tennessee

R. J. Fields

October 1978

Investigation of Appropriate Fracture Criteria for Si^N^ at High

Temperatures

American Ceramic Society, 81st Annual Meeting, Cincinnati, Ohio

R. J. Fields

April 1979

Effective Heat Treatment on the Oxidation of Hot-Pressed Si^N, as Determined by Infrared Reflection Analysis

American Ceramic Society Conference on Composites and Advanced

Materials, Cocoa Beach, Florida

S. W. Freiman, J. M. Barrett, L. L. Hench, S. Bernstein, and

D. E. Clark

January 1979

Fracture Mechanics Applied to Ceramics

ASTM Subcommittee E24.02 Meeting, Atlanta, Georgia

S. W. Freiman

February 1979

Effect o.f Crack Velocity on Fracture Morphology in Ceramics

American Ceramic Society, 81st Annual Meeting,- Ci ncinnati , Ohio

S. W. Freiman, J. J. Mecholsky, and A. C. Gonzalez

May 1979

Current Status of Predicting Service Lifetimes for Ceramic Implants

Biomaterials, Gordon Conference, Tilton, New Hampshire

S. W. Freiman

July 1979

Effects of Surface on the Mechanical Properties of Ceramics

Sagamore Conference, Sagamore, New York

S. W. Freiman, J. J. Mecholsky, and P. F. Becher

July 1979

119
Atmospheric Influences on Brittle Crack Propagation

Ceramic Engineering Seminar, University of Illinois, Urba.na, Illinois

E. R. Fuller, Jr.

December 1978

Cementing of Geothermal Well s-Property Verification

API Task Group on Cements for Geothermal Wells, Houston, Texas

E. R. Fuller, Jr.

January 1979

The Ductile-Brittle Character of Fracture

American Physical Society 1979 March Meeting, Chicago, Illinois

E. R. Fuller, Jr.

March 1979

Kinetics of Chemically Assisted Brittle Fracture

American Ceramic Society, 81st Annual Meeting, Cincinnati, Ohio

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

May 1979

Mechanical Property Testing of Refractory Concretes at High Pressure and Temperature

American Ceramic Society, 81st Annual Meeting, Cincinnati, Ohio

E. R. Fuller, Jr., S. M. Wiedernorn, and D. E. Roberts

May 1979

Considerations of the Ductile-Brittle Character of Fracture

American Ceramic Society, 81st Annual Meeting, Cincinnati, Ohio

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

May 1979

Stress Waves from Particle Impact

Office of Naval Research Workshop on the Erosion of Materials, NBS,

Gaithersburg, Maryland

E. R. Fuller, Jr.

June 1979

Computer Assisted Impact Testing

ASTM Symposium on Computer Automation of Materials Testing, ASTM

Committees E-24 and E-28, Philadelphia, Pennsylvania

C. G. Interrante

November 1978

A System for Studies of Crack-Growth Rate in Aggressive Environments

ASTM Symposium on Computer Automation of Materials Testing, ASTM

Committees E-24 and E-28, Philadelphia, Pennsylvania

C. G. Interrante

November 1978

120
Railroad Tank Car Problems .

, Seventh Fracture and Deformation Division Seminar, NBS, Washington, D.C. C. G. Interrante

December 1978 ^

Analysis of Railroad Tank-Car Failures

The American Welding Society, Northeast Tennessee Section,

Oak Ridge, Tennessee

C. G. Interrante-

‘ March 1979

Impact Testing of Metallic Materials with Emphasis on Test Methods,

Instrumentation, and Acquisition and Analysis of Data

Building Composites Group Seminar, NBS, Washington, D.C.

C. G. Interrante

April 1979

Status of DoT Fracture Mechanics Pipeline Welding Research

Pipeline Welding and Inspection Conference, Houston, Texas

M. B. Kasen

February 1979

Significance of Flaws in Girth Welds of Pipelines

Paton Institute of Electrowelding, Kiev, USSR

M. B.. Kasen

June 1979

Practice for Property Testing of Geothermal Cements

Standardization Conference of American Petroleum Institute,

San Diego, California

R. F. Krause, Jr.

June 1979

Proposed Practice for Testing Geothermal Cements

API Task Group on Cements for Geothermal Wells, San Diego, California

R. F. Krause, Jr., and E. R. Fuller, Jr.

June 1979

NBS/DoE Welding Program

NBS/DoE Workshop on Materials at Low Temperatures , Vail, Colorado

H. I. McHenry

October 1978

Ship Steels with Improved Toughness and Wei dab ility

AWS Conference on Welding in Shipbuilding: Productivity and

Economics, San Diego, California

H. I. McHenry

March 1979

Fitness for Purpose Evaluation of Defects in Pipeline Girthwelds

ASME Conference on Structural Integrity, Washington, D.C.

H. I. McHenry

May 1979

121
Structural Alloys for Superconducting Magnets in Fusion Energy

Systems

Fifth International Conference on Structural Mechanics in Reactor

Technology, Berlin, West Germany

H. I. McHenry

August 1979

Mechanical Properties of Austenitic Stainless Steel Base- and

Weld-Metal

NBS/DoE Workshop on Materials at Low Temperatures, Vail, Colorado

R. P. Reed

October 1978

Structures, Insulators, and Conductors for Large Superconducting

Magnets

First Topical Conference on Fusion Reactor Materials, Miami, Florida

R. P. Reed, F. R. Fickett, and E. N. C. Dalder

January 1979

Low Temperature Effects of Defects in Stainless Steel Welds

Patorr Institute of Electrowelding, Kiev, USSR

R. P. Reed

June 1979

The Effect of High Temperature Processes on Predictive Testing

American Ceramic Society, 81st Annual Meeting, Cincinnati, Ohio

N. J. Tighe

May 1979

Analysis of the Refractories from a Coal Gasification Plant (CO^

Acceptor Process)

American Ceramic Society, Bedford Springs, Pennsylvania

S. M. Wiederhorn

October 1978

Erosion of Ceramics

NACE Conference on Erosion/Corrosion of Coal Conversion System

Materials, Berkeley, California

S. M. Wiederhorn

January 1979

High Temperature Fracture of Ceramic Materials

DoE Workshop on Time Dependent Fracture, Germantown, Maryland

S. M. Wiederhorn

February 1979

Effect of Fluid Viscosity on Crack Propagation

American Ceramic Society, 81st Annual Meeting, Cincinnati, Ohio

S. M. Wiederhorn

April 1979

122
Structural Ceramics

DoE Workshop on Coal Conversion Systems, Knoxville, Tennessee

S. M. Wiederhorn

June 1979

H Erosion of Ceramics i Energy Materials Coordinating Committee Conference on Structural

Ceramics, sponsored by DoE, Knoxville, Tennessee

S. M. Wiederhorn i June 1979

Publications

Evaluation of LNG Sampling-Measurement Systems for Custody Transfer

J. M. Arvidson, W. R. Parrish and J. F. LaBrecque

AGA Operating Section Proceedings, 1978

Proceedings of Transmission Conference, Montreal, Quebec, Canada,

May 8-10, 1978, and Distribution Conference, Denver, CO, May 22-24, 1978

American Gas Association, Arlington, Virginia, T-236-42 (1978).

Reactivity and Strength Development of CO^ Activated Non-Hydraul ic

Calcium Silicates

“

J. M. Bukowski and R. L. Berger

Cement and Concrete Res. 9, 57-68 (1979).

Micromechanical Properties of Beryllium and Other Instrument

Material

s

B. W. Christ and R. S. Polvani

NBSIR 78-1569 (1978).

Hydrogen Diffusion in Palladium by Galvanostatic Charging

J. G. Early

Acta Metal 1 . 26, 1215 (1978).

A Metallurgical Analysis of an ASTM A212-B Steel Tank Car Head

Plate

J. G. Early

NBSIR 78-1582 (1978).

Effect of the Phase Transformation on the Fracture Behavior of

BaTiO

S. W. Freiman, R. C. Pohanka, and B. A. Bender

J. Am. Ceram. Soc. 61_ (1-2), 72-75 (1978).

Fracture Mechanics Applied to Structural Ceramics

S. W. Freiman and S. M. Wiederhorn

Fracture Mechanics, N. Perrone, H. Leibowitz, D. Mulville, and

W. P i 1 key , editors

University Press of Virginia, Charlottesville, Virginia (1978),

pp. 299-316.

123
Microstructural Dependence of Fracture Mechanics Parameters in

Ceramics

S. W. Freiman, R. W. Rice, R. C. Pohanka, J. J. Mecholsky, and

C. Cm. Wu

Fract. Mech. Ceram. 4, 849 (1978).

Delayed Failure of CVD ZnSe

S. W. Freiman, K. R. McKinney, and J. J. Mecholsky

J. Am. Ceram. Soc. 52, 7-8 (1979).

Determination of Fracture Mechanics Parameters through Fractographic Analysis of Ceramics

S. W. Freiman and J. J. Mecholsky

ASTM STP 678 (1979).

Effect of Heat Treatment on the Oxidation of Hot Pressed Si~N* as Determined by Infrared Reflection Analysis

S. W. Freiman, J. M. Barrett, L. L. Hench, S. Bernstein, and

D. E. Clark

Proceedings of the Second Annual Conference on Advanced Materials, 1979.

Fracture Mechanics Applied to Brittle Materials

S. W. Freiman, editor

ASTM STP 678 (1979).

Fracture Mechanics of Glass, Chapter 2

S. W. Freiman

Glass: Science and Technology, Vol. 5, Dr. D. R. Uhlmann and

N. J. Kreidl, editors

1979

Lattice Theories of Fracture

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

Fracture Mechanics of Ceramics, Vol. 4: Crack Growth and Microstructure, R. C. Bradt, D. P. H. Hasselman, and F. F. Lange, editors

Plenum Press, New York (1978), pp. 507-548.

Theory of Chemically Assisted Fracture

E. R. Fuller, Jr. and R. M. Thomson - . Proceedings of the Third International Conference on Mechanical

Behavior of Materials, August 20-24, 1979

University of Cambridge, Cambridge, England.

Erosion of Brittle Materials by Solid Particle Impact

B. J. Hockey, S. M. Wiederhorn, and H. Johnson

Fracture Mechanics of Ceramics, Vol. 3, R. C. Bradt, D. P. H. Hasselman,

and F. F. Lange, editors

Plenum Press, New York (1978).

124
Needed: A Fracture Mechanics Vocabulary

C. G. Interrante

ASTM Standardization News 1(4-) (April, 1979).

Standard Terminology Relating to Fracture Testing

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, Chairman

ANSI/ASTM E616-8, Annual Book of ASTM Standards, Part 10

American Society for Testing and Materials, Philadelphia,

Pennsylvania (1979).

Composite Laminate Applications in Magnetic Fusion-Energy Superconducting Magnet Systems

M. B. Kasen

Proceedings of the Second International Conference on Composite

Materials, B. R. Noton, R. A. Signorelli, K. N. Street, and

L. N. Phillips, editors

Metallurgical Society of the AIME, Warrendale, Pennsylvania (1978),

pp. 1493-1507.

Composite Materials for Cryogenic Structures

M. B. Kasen

Advances in Cryogenic Engineering, Vol. 24, Proceedings of Second I CMC,

Boulder, Colorado, August- 3-5, 1977, K. D. Timmerhaus, R. P. Reed, and

A. F. Clark, editors

Plenum Press, New York (1978), pp. 63-73.

A Low-Temperature Materials Research Program for Magnetic Fusion

Energy

M. B. Kasen, F. R. Fickett, H. I. McHenry, and R. P. Reed

Advances in Cryogenic Engineering, Vol. 24, Proceedings of the

Second ICMC, Boulder, Colorado, August 3-5, 1977

K. D. Timmerhaus, R. P. Reed, and A. F. Clark, editors

Plenum Press, New York (1978), pp. 52-62.

Cryogenic Applications of Composite Technology in the U.S.A.

M. B. Kasen

Nonmetal lie Materials and Composites at Low Temperatures

Proceedings of ICMC Symposium, Munich, Germany, July 10-11, 1978,

A. F. Clark, R. P. Reed, and G. Hartwig, editors

Plenum Press, New York (1979), pp. 317-337.

High-Pressure Industrial Laminates for Cryogenic Applications

M. B. Kasen

Composites Technol. Rev. 1 (3), 17 (1979).
Thermodynamics of Vaporization of Molybdenum Pentafluoride

R. F. Krause, Jr.

Proceedings of the Symposium on High Temperature Metal Halide

Chemistry, Vol. 78-1, H. L. Hildenbrand and D. D. Cubicciotti,

editors

The Electrochemical Society, Princeton, New Jersey (1978), pp. 199-209.

Elastic Constants at Low Temperatures: Recent Measurements on Technological Materials at NBS

H. M. Ledbetter

Advances in Cryogenic Engineering, Vol. 24

Proceedings of Second ICMC, Boulder, Colorado, August 3-5, 1977

K. D. Timmerhaus, R. P. Reed, and A. F. Clark, editors

Plenum Press, New York (1978), pp. 161-165.

Dyanmic Elastic Modulus and Internal Friction in Fibrous Composites

H. M. Ledbetter

Nonmetal lie Materials and Composites at Low Temperatures

Proceedings of ICMC Symposium, Munich, Germany, July 10-11, 1978

Plenum Press, New York (1979), pp. 267-281.

Dynamic Elastic Modulus and Internal Friction in G-10CR and G-11CR

Fibergl ass-Cl oth- Epoxy Compos i tes

H. M. Ledbetter

NBSIR 79-1609 (1979).

Laser-Induced Rayleigh Waves in Aluminum

H. M. Ledbetter and J. C. Moulder

J. Acoust. Soc. Am. 65 (3): 840-842 (1979).

Low-Temperature Magnetically Induced Elastic-Constant Anomalies in

Three Manganese Stainless Steels

H. M. Ledbetter and E. W. Collings

Proceedings of the Conference on Metal Science of Stainless Steels

Metallurgical Society of the AIME, New York (1979).

Sound Velocity Anomalies Near the Spin Glass Transition in an Austenitic Stainless Steel Alloy

H. M. Ledbetter and E. W. Collings

Phys. Lett. 72A, 53-55 (1979).

Alkali Ion Exchange Reactions with RbAlSiO.: A New Metastable

Polymorph of KAlSiO.

C. L. McDaniel, D. B. Minor, R. S. Roth, and W. S. Brower

Mater. Res. Bull. 1_3, 575-581 (1978).

Magnetic Susceptibility of Cerium Tantalate Compounds

C. L. McDaniel, G. A. Candela, A. H. Kahn, and T. Negas

The Rare Earths in Modern Science and Technology, G. J. McCarthy

and J. J. Rhyne, editors

Plenum Press, New York (1978), pp. 441-446.

126
Low- Temperature Fracture Properties of a USSR Aluminum-6% Magnesium

Alloy

H. I. McHenry, S. E. Naranjo, D. T. Read, and R. P. Reed

Advances in Cryogenic Engineering, Vol. 24

Proceedings of Second ICMC, Boulder, Colorado, August 3-5, 1977,

K. D. Timmerhaus, R. P. Reed and A. F. Clark, editors

Plenum Press, New York (1978), pp. 519-528.

Note on the Fracture Properties of Fe-49Ni at Cryogenic Temperatures

H. I. McHenry and R. E. Schramm

Advances in Cryogenic Engineering, Vol. 24

Proceedings of Second ICMC, Boulder, Colorado, August 3-5, 1977,

K. D. Timmerhaus, R. P. Reed and A. F. Clark, editors

Plenum Press, New York (1978), pp. 161-165.

Evaluation of Stainless Steel Weld Metals at Cryogenic Temperatures

H. I. McHenry, D. T. Read, and P. A. Steinmeyer

Materials Studies for Magnetic Fusion Energy Applications at Low

Temperatures - II

NBSIR 79-1609 (1979).

Fitness-for-Purpose Evaluation of Defects in Pipeline Girthwelds

H. I. McHenry

Structural Integrity Technology, J. P. Gallagher and T. W. Crooker,

editors

American Society of Mechanical Engineers, New York (1979).

Fracture Mechanics Analysis of Pipeline Girthwelds

H. I. McHenry, D. T. Read, and J. A. Begley

Elastic-Plastic Fracture, J. D. Landes, J. A. Begley, and G. A. Clarke, editors

ASTM STP 668 (1979), pp. 632-642.

Microcreep of Instrument Grade Beryllium

R. S. Polvani and B. W. Christ

Proceedings of the 24th National SAMPE (Society for Advancement of

Material and Process Engineering) Symposium, C. H. Marschall , editor

San Francisco, California, May, 1979

Metallurgical Effects in Niobium-Titanium Alloys

D. T. Read

Cryogenics, 18 (10), 579-584 (1978).

Definitions of Terms for Practical Superconductors. 3. Fabrication, Stabilization, and Transient Losses

D. T. Read, J. W. Ekin, R. L. Powell, and A. F. Clark

Cryogenics ]9 (6), 327-332 (1979).

127
Advances in Cryogenic Engineering, Vol. 24

Proceedings of Second ICMC, Boulder, Colorado, August 2-5, 1977,

R. P. Reed, K. D. Timmerhaus, and A. F. Clark, editors

Plenum Press, New York (1978), 598 pages.

Low Temperature US/USSR Material and Weld Properties for LNG

Applications — Part 1 R. P. Reed and K. A. Yushchenko

Proceedings of the Seventh International Cryogenic Engineering

Conference, London, England, July 4-7, 1978

IPC Science and Technology Press, Guildford, Surrey, England (1978),

pp. 474-486.

Investigations of Steels and Weld Properties According to the

USSR/USA Cooperative Program — Part 2

R. P. Reed and K. A. Yushchenko

Proceedings of the Seventh International Cryogenic Engineering

Conference, London, England, July 4-7, 1978

IPC Science and Technology Press, Guildford, Surrey, England (1978),

pp. 487-493.

A Fracture Mechanics Evaluation of Flaws in Pipeline Girth Welds

R. P. Reed, H. I. McHenry, and M. B. Kasen

Weld. Res. Counc. Bull. 245 (1979), 23 pages.

Materials Studies for Magnetic Fusion Energy Applications at Low

Temperatures — II

R. P. Reed and F. R. Fickett, editors

NBSIR 79-1609 (1979).

Nonmetal lie Materials and Composites at Low Temperatures

Proceedings of ICMC Symposium, Munich, Germany, July 10-11, 1978

R. P. Reed, A. F. Clark, and G. Hartwig, editors

Plenum Press, New York (1979), 456 pages.

Fiberglass-Epoxy in a Conical Superconducting Field Magnet Support

R. E. Schramm and M. B. Kasen

Advances in Cryogenic Engineering, Vol. 24

Proceedings of Second ICMC, Boulder, Colorado, August 3-5, 1977,

K. 0. Timmerhaus, R. P. Reed, and A. F. Clark, editors

Plenum Press, New York (1978), pp. 271-278.

Effect of Strain on Epoxy- Impregnated Superconducting Composites

R. E. Schramm, J. W. Ekin, and A. F. Clark

Nonmetallic Materials and Composites at Low Temperatures

Proceedings of ICMC Sympoisum, Munich, Germany, July 10-11, 1978,

A. F. Clark, R. P. Reed, and G. Hartwig, editors

Plenum Press, New York (1979), pp. 301-308.

128
Examination of Failed Four-Inch Diameter Cast Iron Pipe Natural Gas

Main, Hamden, Connecticut

T. R. Shives

NBSIR 78-1470 (1978).

Examination of Failed One-Inch Diameter Bare Steel Pipe Natural Gas

Service Line, Waynesboro, Virginia, Columbia Gas Company of Virginia,

Inc.

T. R. Shives

NBSIR 78-1572 (1978).

Examination of Components from a Mahler-Weber PJ260 Aircraft

T. R. Shives

NBSIR 79-1597 (1979).

Operating Experiences with Alloy 800 in Coal Conversion Process

Plants

J. H. Smith

Proceedings of International Conference on Alloy 800, 1978

Quantitative Stereological Methods for Analyzing Important Microstructural Features in Fatigue of Metals and Alloys

J. H. Smith

ASTM STP 675 (1979).

Fatigue Crack Growth Resistance of Structural Alloys at Cryogenic

Temperatures

R. L. Tobler and R. P. Reed

Advances in Cryogenic Engineering, Vol. 24, Proceedings of Second

ICMC, Boulder, Colorado, August 3-5, 1977, K. D. Timmerhaus, R. P. Reed, and A. F. Clark, editors

Plenum Press, New York (1978), pp. 82-90.

Fracture Mechanics Parameters for an Iron-1 3% Chromium-1 9% Manganese Stainless Steel and Its Welds at Cryogenic Temperatures

R. L. Tobler, H. I. McHenry, and R. P. Reed

Advances in Cryogenic Engineering, Vol. 24, Proceedings of Second

ICMC, Boulder, Colorado, August 3-5, 1977, K. D. Timmerhaus, R. P. Reed, and A. F. Clark, editors

Plenum Press, New York (1978), pp:' 560-572.

Low Temperature Fracture Behavior of a Ti - 6A1 -4V Alloy and its

Electron Beam Welds

R. L. Tobler

Toughness and Fracture Behavior of Titanium

ASTM STP 651 (1978), pp. 267-294.

129
Cryogenic Effects on the Fracture Mechanics Parameters of Ferritic

Nickel Alloy Steels

R. L. Tobler, R. P. Mikesell, and R. P. Reed

Elastic-Plastic Fracture, J. D. Landes, J. A. Begley, and G. A. Clarke,

editors

ASTM STP 668 (1979).

Tensile and Fracture Behavior of a Nitrogen-Strengthened, ChromiumNickel -Manganese Stainless Steel at Cryogenic Temperatures

R. Tobler and R. P. Reed.

ASTM STP 668 (1979).

Proof Testing of Hot-Pressed Silicon Nitride

S. M. Wiederhorn and N. J. Tighe

J. Mater. Sci. 13, 1781-93 (1978).

Application of Fracture Mechanics Concepts to Structural Ceramics

S. M. Wiederhorn and J. E. Ritter, Jr.

Proceedings of the 11th National Symposium on Fracture Mechanics, Blacksburg, Virginia, June 12-14, 1978

ASTM STP 678 (1979).

Strength Degradation of Glass Impacted with Sharp Particles,

I. Annealed Surfaces

S. M. Wiederhorn and B. R. Lawn

J. Am. Ceram. Soc. 62, 66-70 (1979).

Strength Degradation of Glass Impacted with Sharp Particles,

II. Tempered Surfaces

S. M. Wiederhorn, D. B. Marshall, and B. R. Lawn

J. Am. Ceram. Soc. 62, 71-74 (1979).

Seminars for Staff and Guests

D. J. Barber

Deformation of Dolomite

July 2, 1979

P. Beaumont

Micromechanisms of Fracture "in Fibrous Composites During

Monotonic Loading

June 18, 1979

J. A. Begley

Fracture Mechanics and Corrosion

February 4, 1979

S. J. 3urns

Thermodynamics of Fracture

May 29, 1979

130
A. L. Broz

Projects in the Nondestructive Testing Field

July 23, 1979

G. C. Che 1

1

The Significance of Warm Prestress in Understanding and Interpreting Failure Criteria

January 4, 1979

T.-J. Chuang

A Plane-Strain Elasticity Model for the Diffusive Growth of an Intergranular Creep Crack

August 7, 1979

R. L. Crane

The Nondestructive EvaVuati on/Fracture Mechanics Interface

April 5, 1979

R. L. Crane

Consultation on Nondestructive Evaluation Procedures for Welds in

Gas Transmission Pipelines

May 14, 1979

R. DeWit

The R-Curve in Fracture Mechanics

October 31 , 1978

R. DeWit

The R-Curve in Fracture Mechanics II

January 23, 1979

R. DeWit

A Summary of Fracture Mechanics Concepts

April 3, 1979

J. G. Early

Report on Selected Topics from the Railroad Tank Car and Hydrogen

Embrittlement Programs

December 12, 1978

C. Fortunko

Projects in the Nondestructive Testing Field

July 27, 1979

S. W. Freiman

Fractographic Analysis of Ceramics

October 17, 1978

S. W. Freiman

Fracture Mechanics for Structural Ceramics

October 27, 1978

131
H. Frost

The Application of Physical Acoustics to Nondestructive

Evaluation

March 15, 1979

E. R. Fuller, Jr.

Atomistic Influences on Brittle Crack Propagation

December 1, 1978

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

Theory of Chemically Assisted Fracture: A Progress Report

February 6, 1979

A. H. Heuer

Precipitation in Star Sapphire

June 12, 1979

C. G. Interrante

Railroad Tank Car Problems

December 5, 1978

F. F. Lange

Transformation Toughening of Ceramics

June 1 , 1979

B. R. Lawn

Elastic/Plastic Indentation Fracture in Brittle Solids

April 17, 1979

C. J. McMahon, Jr.

Embrittlement of Steels by Solute Segregation

May 8, 1979

R. S. Polvani

Using Beryllium for Gyroscopes

January 9, 1979

N. J. Tighe

Ceramics for Turbine Engines

March 6, 1979

T. Suzuki

Phonon Dispersion and Martensitic- Transformations

February 21 , 1979

T. Suzuki

Elastic Constants and Structural Phase Transitions

July 2, 1979

S. M. Wiederhorn and B. J. Hockey

Effect of Temperature on the Erosion of Ceramics

October 3, 1978

132
S. M. Wiederhorn

Mechanisms of Erosive Wear in Ceramic Materials

April 4, 1979

R. S. Williams

Nondestructive Evaluation of Fracture Mechanics

May 25, 1979

Special Reports

Micromechanical Properties of Beryllium and Other Instrument

Material

s

B. W. Christ, R. S. Polvani, and R. J. Hocken

Technical Report No. 17

Office of Naval Research, Boston, Massachusetts (October, 1978).

Ballistic Resistance of Police Body Armor

R. C. Dobbyn and N. J. Calvano

NILECJ-STD-01 01-01

U.S. Department of Justice, Law Enforcement Assistance Administration

Washington, D.C. (December, 1978).

Report by the Ad Hoc Committee of the Office of the Assistant

Secretary for Science and Technology, Preliminary Technical Evaluation of a Proposal to Revive the Steel making Industry in

Youngstown, Ohio

J. G. Early, et al

.

(1978).

Compressive, Tensile, Pipe-Bonding Strengths, and Permeability of

Selected Cementing Materials for Hot-Dry-Rock Wells

R. F. Krause, Jr. and E. R. Fuller, Jr.

in Cementing of Geothermal Wells Progress Report No. 10, BNL

Report 50943

Brookhaven National Laboratory, Upton, New York (January, 1979).

Materials for Superconducting Magnets for MHD Power Systems, A

Usage Survey and a Proposed Research Program

R. P. Reed, H. I. McHenry, M. B. Kasen, F. R. Fickett, and

E. N. C. Dalder

Francis Bitter National Magnet Laboratory, MIT (June, 1979).

Examination of Bicycle Cranks

T. R. Shives

NBS Report (1978).

Fuselage Fuel Booster Pump from Lear Aircraft

T. R. Shives

NBS Report (1978).

Hardness Measurements on Flat Springs

T. R. Shives

NBS Report (1978).

133
Hardness Measurements and Metal! ographic Examination of Barbed

Tape Specimens

T. R. Shives

NBS Report (1978).

Product Durability and Life

T. R. Shives and W. A. Willard, editors

Mechanical Failure Prevention Group Proceedings, 1978

NBS Special Publication 514 (1978).

Tensile Force Required to Separate Brazed Joints in Aircraft Seatbelt Anchorage Fittings

T. R. Shives

NBS Report (1978).

Tensile Properties and Hardness of El ectroformed Nickel Printing

Plate

T. R. Shives

NBS Report (1978).

Testing of Floor Panels

T. R. Shives

NBS Report (1978).

Characterization of DeLaRue Plate Material

T. R. Shives

NBS Report (1979).

Detection, Diagnosis, and Prognosis

T. R. Shives and W. A. Willard, editors

Mechanical Failure Prevention Group Proceedings, 1979

NBS Special Publication 547 (July, 1979).

Examination of Failed Lawn Mower Engine Crankshaft

T. R. Shives

NBS Report (1979).

Hardness Measurements on Three Sets of Submitted Beryl 1 ium-Copper

Parts

T. R. Shives

NBS Report (1979).

Hardness Measurements on HDL Test Pieces

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).

134
Tensile Properties, Hardness Measurements, and Metal lographic

Examination of Submitted Electroformed Nickel Printing Plate

T. R. Shives

NBS Report (1979).

Technical and Professional Committee Participation and Leadership

American Association for the Advancement of Science

S. W. Freiman, B. J. Hockey, J. H. Smith

American Ceramic Society

Members: J. M. Bukowski, S. W. Freiman (Secretary of Glass Division), E. R. Fuller, Jr. (Secretary-Treasurer of the

Baltimore-Washington Section), B. J. Hockey, C. L. McDaniel, N. J. Tighe

Committee Participation:

Executive Committee: N. J. Tighe

Forum Committee: N. J. Tighe

Sosman Lecture Committee: N. J. Tighe

American Chemical Society

Members: R. F. Krause, Jr., C. L. McDaniel, S. M. Wiederhorn

Committee Participation:

Editorial Committee Subchairman: S. M. Wiederhorn

American Institute for Mining, Metallurgical and Petroleum

Engineers (AIME)

Metallurgical Society: B. W. Christ, R. deWit (Key Reader),

J. G. Early, R. S. Polvani, J. H. Smith

American Iron and Steel Institute

Task Force on Evaluation of Fracture Criteria for Ship Steels and

Weldments: H. I. McHenry

American National Standards Institute (ANSI)

Materials and Stresses Committee of the Pressure Piping Code, B31:

H. I. McHenry

American Petroleum Institute

Task Group on Cements for Geothermal Wells: E. R. Fuller, Jr.

American Physical Society

R. C. Dobbyn, E. R. Fuller, Jr., R. deWit, E. R. Fuller, B. J. Hockey

135
American Society for Metals (ASM)

Members: B. W. Christ, J. G. Early, G. E. Hicho, C. G. Interrante

(Past Chairman, Washington Chapter), H. I. McHenry,

T. R. Shives, N. J. Tighe

Committee Participation:

Long Range Planning Committee: C. G. Interrante (Chairman)

Metals Information Publications Committee: J. H. Smith

American Society for Testing and Materials (ASTM)

Members: R. deWit, R. C. Dobbyn, B. W. Christ, J. G. Early, S. W.

Freiman, G. E. Hicho, C. G. Interrante, M. B. Kasen,

T. R. Shives, J. H. Smith, R. L. Tobler, S. M. Wiederhorn

Committee Participation:

COT Committee on Terminology of Committee on Standards:

C. G. Interrante

Committee C-21 Ceramic Whitewares: S. M. Wiederhorn

Committee D30 Composite Materials: M. B. Kasen

Subcommittee D30.05 High-Modulus Fibers and Their

Composites: M. B. Kasen

Subcommittee E9.03 Fatigue of Composites: M. B. Kasen

Subcommittee E10.02-D Computer Methods for Analysis of

Charpy Data: C. G. Interrante

Committee E24 Fracture Testing: B. W. Christ (Member

of Executive Committee), E. R. Fuller, Jr., G. E. Hicho,

C. G. Interrante (Member of Executive Committee),

J. H. Smith, R. L. Tobler, S. M. Wiederhorn

Task Group E24.01.09 Elastic Fracture: R. L. Tobler

Subcommittee E24.03 Alternative Test Methods: B. W.

Christ (Chairman)

Task Group E24.03.03 Precracked Charpy Testing Methods:

C. G. Interrante

Subcommittee E24.03 on Terminology: C. G. Interrante

(Chairman), R. deWit (Secretary), J. H. Smith

Subcommittee E24.07: S. W. Freiman (Chairman)

Task Group E28.04.03 Verification of Alignment Under

Tensile Load: B. W. Christ (Chairman)

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: B. W. Christ (Guest

Member representing NBS), R. P. Reed

136
American Society of Mechanical Engineers (ASME)

Members: R. deWit, R. C. Dobbyn, J. H. Smith, N. J. Tighe

Committee Participation:

Ceramics Committee: N. J. Tighe

Gas Turbine Division: N. J. Tighe

Joint Applied Mechanics Division and Materials Division

Committee on Constitutive Equations: R. deWit

Subcommittee 109, Materials and Fabrication, Pressure

Vessel and Piping Division: R. C. Dobbyn (Chairman)

American Welding Society

Members: C. G. Interrante, H. I. McHenry, J. H. Smith

Committee Participation:

Conference Program Advisory Board, Evaluation of Welded

Structures Based on Fitness for Service: H. I. McHenry

(Chairman)

Technical Activities Committee: H. I. McHenry (Memberat- Large)

Ceramic Educational Council

J. M. Bukowski

Compressed Gas Association

Cylinder Specification Subcommittee

B. W. Christ

Department of Energy

Subcommittee on Erosion/Corrosi on of Turbine Materials: B. J. Hockey

Department of Transportation

Technical Pipeline Safety Standards Committee: B. W. Christ

(appointment by Secretary of Transportation)

Interagency Coordination Group for the Application of Ceramics to

Heat Engines

S. M. Wiederhorn

International Commission on Glass

Subcommittee VI A: S. M. Wiederhorn (Chairman)

International Cryogenic Materials Conference Board

R. P. Reed (Chairman)

International Institute of Welding

Commission XV - Fundamentals of Design and Fabrication for Welding:

J. H. Smith

137
International Powder Metallurgy Society (Planseeberichte fgr

Pulvermetallurgie, Austria)

J. G. Early

International Society for Stereo logy

R. deWit

International Standards Organization (ISO)

ISO/TC 164 on- Mechanical Testing: C. G. Interrante

ISO/TC 164/SC4 on Toughness Testing: C. G. Interrante

ISO/TC 164/WG1 on Terms, Symbols, Definitions: C. G. Interrante

Keramos

J. M. Bukowski

Maryland Institute of Metals

R. deWi t

Mechanical Failures Prevention Group

T. R. Shives (Editor), W. A. Willard (Editor)

Metals Properties Council (MPC)

Committee on Materials for the Gasification and Liquefaction of

Coal: J. H. Smith

Technical Advisory Committee: • R. P. Reed

National Academy of Sciences (NAS)

Project Advisory Committee on Investigation of Steels for Im

proved Weldability in Ship Construction: H. I. McHenry (Chairman)

Ship Materials, Fabrication and Inspection Advisory Group of the

Ship Research Committee: H. I. McHenry

National Institute of Ceramic Engineers

J. M. Bukowski (Associate Member)

National Materials Advisory Board (NMAB)

Committee on Reliability of Ceramics for Heat Engine Applications:

S. M. Wiederhorn

National Research Council

Committee on Recommendations for U.S. Army Basic Scientific

Research: S. M. Wiederhorn

New York Academy of Sciences

R. deWit

Office of Energy-Related Inventions

Reviewer of Invention Disclosures: J. G. Early

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, OH: J. G. Early,

J. H. Smith

138
Sigma Xi

B. J. Hockey, J. H. Smith, FL S. Polvani, S. W. Freiman

Society for Natural Philosophy

R. deWit

Standards Committee for Women

N. J. Tighe

U.S. Civil Service Examiners for Metallurgist, Interagency Board

J. G. Early (Chairman)

University of Washington Program on the Nature and Properties of

Ceramic Materials Advisory Committee: S. M. Wiederhorn

Washington Academy of Sciences

R. deWit

Washington Society for Electron Microscopy

B. J. Hockey

Welding Research Council (WRC)

Long Range Planning Committee: H. I. McHenry

Pressure Vessel Research Committee (PVRC): C. G. Interrante,

G. E. Hicho

PVRC Hydrogen Embrittlement Subcommittee: C. G. Interrante,

G. E. Hicho

Subcommittee on Line Pipe Steels: M. B. Kasen, H. I. McHenry

Task Group on Field Welding: M. B. Kasen, H. I. McHenry

Weldability (Metallurgical) Committee: H. I. McHenry

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

Geothermal Well Cementing Advisory Panel

E. R. Fuller

Interagency Coordination Group for the Application of Ceramics to

Heat Engines

S. M. Wiederhorn

National Materials Advisory Board Committee on Ceramics for Heat

Engi nes

S. M. Wiederhorn

139
Ship Materials Fabrication and Inspection Advisory Group of the

Ship Research Committee (National Academy of Sciences)

H. I. McHenry

Welding Research Council Long-range Planning Cooperative Technology

Program

H. I. McHenry

140
POLYMER SCIENCE AND STANDARDS DIVISION

141
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POLYMER SCIENCE AND STANDARDS DIVISION

Ronald K. Eby, Chief

Darrell H. Reneker, Deputy Chief

P. C. Colbert, Secretary

H. E. Kistler, Secretary

In the 70 years since Baekeland introduced the first commercial

plastic produced entirely by the reaction of small molecules, plastics

have left little of our culture and our technology untouched. We have

moved rapidly into an age in which an overwhelming number of the needs

of mankind are served by plastics.

In 1976, the last year for which comprehensive figures are available, over 22 teragrams of synthetic polymer were produced. This

amounts to tens of billions of dollars worth of materials produced in

hundreds of manufacturing plants where hundreds of thousands of workers

are employed. Plastics production is currently growing at a rate of 9%

per year. In addition to the domestic needs served, the polymer industry presently produces a two billion dollar favorable balance of trade.

Important trends in the polymer industry include increased use of

polymers in packaging, in automobiles to reduce weight and improve fuel

economy, in electronic and information handling applications, and in

medical implants. These increasingly sophisticated and demanding

applications have created new needs for concepts, measurements, standards, and data that can be used to insure that plastics perform as intended not only in the use environment, but in processing and other

phases of the materials cycle as well.

Long-range planning activities included visits by the Division

managers to the polymer research laboratories of Proctor and Gamble.

Army Research and Development Command, General Motors, Boeing Commercial Airplane, and Lawrence Livermore Laboratory.

The costs associated with the limited durability of plastics were

estimated by a survey of industrial trade associations and academic

sources. It appears that this survey is the first of this sort ever

attempted for plastics. The uncertainties in our estimates are therefore large because of the sparse data base. Significant economic costs

related to limited durability appear in the following applications of

polymers: Building, Transportation, Energy Transmission, Appliances,

Dental and Medical Applications. Costs associated with limited durability of plastics in all areas appear to be in the range of 6 to 12

billion dollars per year.

A survey of polymer processing science and technology was also

completed. Attention was focused on the processing of polymer blends

and on the biaxial orientation of polymers because of the large growth

potential of these processes. Many contacts with experts in industry

143
and university laboratories were made to gather information about the

future prospects for these areas of polymer processing. The report

also contains information about more conventional polymer processing

methods, including injection molding, extrusion blow molding, thermoforming, structural foam, rotomolding and reaction injection molding.

These planning activities help insure that the future efforts of

the Division will be responsive to the themes outlined by the Director

of NBS in his State of the Bureau address. These are the healthy

growth of industrial productivity, prudent utilization of energy

sources, a reasonable system for the regulation of the effects of

technology and a wise policy of materials utilization.

Major problems now being addressed by Division projects include:

o A cooperative effort with the Bureau of Foods to produce

methods of improved reliability for predicting both the

rates of migration of small molecules from plastic containers

into foodstuffs and the equilibrium concentrations that will

be reached.

o Elucidation of the molecular level processes that are responsible for piezoelectric effects in polymers. Applications of

devices based on piezoelectric polymers led to solutions of

measurement problems ranging from improved control of presses

used to print currency to monitoring the intensity of ultrasonic energy used in medical diagnosis and treatment.

o Evaluation of the fatigue resistance of elastomers needed in

efforts supported by the National Institutes of Health to

develop artificial heart components and improved circulatory

assist devices.

o Improved polymer-based dental restorative materials and ad

hesives to make durable bonds between restorative materials

and tooth tissue. This work involves extensive cooperation

with the American Dental Association and the National Institute for Dental Research.

o Characterization of the elastomers used as seals in equipment used to collect energy from geothermal sources in Department of Energy sponsored projects. More durable elastomeric

seals will allow greater use to be made of this potentially

large and cost effective energy source.

o The mechanical durability and permeation behavior of plastics

used in containers for the safe transport of hazardous materials

needed to insure reasonable regulation of such containers by

the Office of Hazardous Materials of the Department of Transportation.

144
These problems and the others detailed in the following pages lead

the scientists in the Division into productive examination of those

properties of polymers which are (or should be) of concern to people

who design and produce useful objects from plastics. This work helps

society capture, in safe and satisfying ways, the benefits of the

increasingly widespread application of plastics.

The activities of the Division are associated into six Tasks, each

described separately below. The Task titles are:

DIELECTRIC PLASTICS DESIGN AND PERFORMANCE

POLYMER STANDARDS FOR CONTROL AND EQUITY

CHEMICAL DURABILITY OF POLYMERS IN USE

MIGRATION AND THE DURABILITY OF PLASTICS IN USE

MECHANICAL DURABILITY OF PLASTICS FOR DESIGN AND USE

TESTS, STANDARDS, AND CHARACTERIZATION FOR MANUFACTURING AND

DURABILITY OF DENTAL AND MEDICAL MATERIALS

145

DIELECTRIC PLASTICS DESIGN AND PERFORMANCE

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,

HEW) need reliable information connecting polymer structure and polymer

performance for 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, how structure control can be

modified to optimize piezoelectric, pyroelectric, and semi-conducti ng

properties.

Technical Activity

Polymer Insulation for Superconducting AC Power Transmission Cables

F. A. Khoury, F. I. Mopsik, S. J. Kryder, and 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

superconduci ng AC transmission cables operated at 6 K - 9 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

147
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 range and 60 Hz.

This subtask is primarily concerned with the measurement of the

dielectric properties (a, 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 among others, relevant to the determination of

the optimum conditions (e.g., tape tension) necessary for winding the

films (slit in the form of tapes) around the cable core, so as to yield

a cable exhibiting appropriate flexibility for winding onto storage

drums 10 ft. in diameter.

For FY 1979 the main concern was to characterize the dielectric

loss of polyurethane board polypropylene laminates. These laminates

consist of polypropylene tapes bound together with a polyurethane

adhesive. The laminates were made in order to form a tape strong

enough to withstand the necessary winding tensions in making a cable

and also be rigid enough not to wrinkle when the cable is wound onto

the storage drums. Also, usually one of the urethane layers was dyed

so that the tapes could be visually monitored during the winding

process.

Several laminates using three layers of 25 pm polypropylene tape

with different urethane formulations and dyes were studied. In addition tapes were delaminated and put back together so that both dyed and

undyed urethane layers could be measured separately. The results

showed that the major sources of dielectric loss in the temperature

range of 4 to 10 K were the sub 4.2 K loss peak in the original polypropylene, which decreases with increasing temperature and the loss due

to the polyurethane which increases with increasing temperature. The

tan 6 at 100 Hz ranged from 18 to 41 x 10_ s

, which is somewhat higher

overall than the desired value of 20 x 10 6

. The only effects dye had

on the loss in these laminates was at higher temperatures above 150 K.

In addition, several laminates made from two layers of a new 50 pm

polypropylene were investigated together with the new polypropylene.

These laminates had tan 5 of 13-18 x 10 6 at 100 Hz in the temperature

range of 4 to 10 K. The lower loss of these laminates was established

as being due to a reduced urethane content and either less antioxidant

or a different type of antioxidant.

148
Compressibility measurements were made on the laminates in order

to predict cable bendability. In addition, the laminates were examined

for void content in the urethane layers in order that control of the

laminating process could be established to minimize the presence of

voids which could serve as a source of electrical discharge.

Polymer Tape Insulation for Oil Impregnated AC Power Transmission

Cables

F. A. Khoury, F. I. Mopsik, S. J. Kryder, and 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 Kv1000 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 of the fine structural characteristics of the

films; and (c) the specification of the dielectrically most suitable type

of film for the intended end use.

In FY 1979, the special dielectric cell needed to measure polymer

films was tested and modified so that it now gives reproducible loss

measurements on polymer films in the temperature range of 300 to 420 K

to a resolution in tan 5 of 1 x 10 6

. In addition, several polymer

films were studied in this temperature range of 100 Hz and 1 kHz. The

samples were studied as a function of several temperature cycles in

order to see if elevated temperatures cause changes in the observed

dielectric loss, possibly signaling aging in the polymer itself. The

samples studied to date include several of the films studied previously

at cryogenic temperatures and several new films prepared by Battelle

Institute for BNL that were extruded, rolled, and drawn from commercial

polymers.

The main features found in the dielectric measurements where the

presence of a loss peak at about 300 K, as seen in earlier measurements,

using the cryogenic equipment and a loss minimum around 350 K followed

by rapidly accelerating loss above this temperature up to maximum test

temperature at 423 K. No sign of the a loss peak near 390 K was found.

The loss varied appreciably among_the different samples studied with

minimum tan 5 at 353 K of 30 x 10 6 which is a very low value. In

addition, mechanical and dielectric instabilities were observed in the

3attelle samples.

149
The Battel! e samples are currently undergoing x-ray diffraction

and morphological studies to characterize them and comparisons will be

made with the heated samples in order to determine the nature of any

temperature induced aging which may have occurred.

Porous Polymer Tapes for High Voltage Transmission Cables

A. J. Bur, M. G. Broadhurst, and W. P. Harris

Existing underground high voltage transmission cables are made

with an insulation consisting of layers of paper tape saturated with a dielectric oil. This system has proved to be adequate for voltages up

to 325 kV. At higher transmission voltages dielectric dispersion in

the paper produces unacceptable dielectric losses. In the foreseeable

future electrical transmission at voltages higher than 235 kV will be

necessary and a substitute for paper is being sought. A polymer material

is a logical choice. Some work on solid polymer films has been carried

out in the past but the permeation of oil throughout the lapped tapes

and encapsulated voids in the films are problems which impede other

uses of solid films. It is possible that porous polymer tapes can overcome these problems through improved oil permeation and decreased

occurrence of unfilled voids.

The Electric Power Research Institute (EPRI) is supporting this

porous polymer tape project. The objective of the project is to establish a screening program by which candidate materials can be tested and

a judgment made regarding their suitability as cable insulation. The

screening program which we have developed consists of criteria for

physical properties which the tapes must have and a description of the

tests by which these physical properties can be measured. On the test

schedule there are 21 tests to measure the following physical properties: dielectric constant, dielectric loss, dielectric breakdown,

softening temperature, mechanical moduli in three directions, coefficient of friction, yield strength, fracture strength, solubility,

creep and recovery, swelling, and degree of void filling.

With the exception of the degree of void filling and solubility

tests, a description of these tests was obtained from literature sources

and ASTM test schedules. The degree of void filling and solubility

tests have been developed through our own laboratory experience. For

these two tests, we have used a method which is designed to measure the

buoyant force of a sample immersed in a dielectric oil.

To measure the degree of void filling, the density of a porous

sample is first measured in a calibration fluid which is chosen because

of its efficient permeation into the material being investigated. (For

example, heptane is known to permeate into polyethylene filling microvoids in the material). It is assumed that this calibration fluid

fills all pores and voids so that the true material density can be

150
obtained from the buoyant force measurement. A buoyant force measurement is then made for the sample immersed in a dielectric oil. The

difference between the true specific volume and the immersed- i n-oi

1

specific volume is equal to- the specific volume of unfilled pores.

Solubility can be measured by weighing the dry sample before and after

immersion in the fluid being tested.

Oil permeation into the sample is a common conditioning step in

many of the dielectric and mechanical tests which must be carried out

in oil. Temperature and vacuum cycling are often necessary in order to

increase the permeation of oil and decrease the unfilled void volume.

The buoyancy measurements are being developed to observe these conditioning parameters.

Four materials and two oils have been used in these experiments.

The materials are a polypropylene synthetic paper (PPSP), a porous

polypropylene (PP), a polyethylene synthetic paper (PE) and a paperpolypropylene-paper laminate (PPP). The oils are an alkyl benzene oil

and a polybutene oil. The results show a range of void filling from

very little for PPSP to complete filling for PP.

A final report for this project has been submitted to EPRI for

publ i cation.

Thick Electrode Transducers

A. J. Bur, H. E. Gilpin, and M. G. Broadhurst

The fabrication of transducer specimens of PVF2 with thick, well

adhering electrodes was attempted. The objective was to study the

influence of the mechanical properties of the electrodes on the PVF2 transducer behavior. It is expected that the hydrostatic response will

be enhanced by a factor of 2 to 3, if the electrodes maintain their own

integrity and exert a stress on the polymer film during temperature

and/or pressure changes. Up to this time transducers 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 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 lOx 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

effect of this stress is to decrease the thickness of the polymer film

via Poisson's ratio. The factor which controls this effect is

1 + v/1 - v (v = Poisson's ratio). For v = 1/2, this factor is 3, i.e.,

threefold enhancement of the change in thickness. Correspondingly,

there should be a threefold increase in the piezoelectric response.

151
At this time we have not successfully made a thick electrode

specimen. Several approaches have been attempted. Initially the

approach which we took was to evaporate 1000 A Ni electrodes onto PVF2

. The speciman was then poled and its piezo- and pyroelectric coefficients

were measured. The speciman was then placed in an electroplating bath

and an attempt was made to plate Cu on top of the Ni to a thickness of 3 pm.

This plating, however, did not adhere well to the Ni. It either did not

plate at all or after plating, flaked off. In spite of the flaking Cu, one apparently intact speciman was measured and found to have the same

piezo- and pyroelectric coefficients as before plating. The speciman

was observed to be electrically noisy and to have a large background

current in the shorted condition, presumably due to ions injected into

the polymer from the plating process.

Other attempts at electroplating included Au plating on Ni , electrodeless Ag plating followed by Cu plating; and Au plating on top of Ag

spray painted electrodes. In all cases where electroplating was used

the specimens became electrically noisy so that in some cases, it was

not possible to measure the coefficients. In other cases the Au and Cu

plated electrodes flacked off. Although two specimens were measured, no conclusions could be drawn from these data.

Brass shim stock, 25 pm thick, was also used for electrodes. In

this case, the brass shim was glued onto an evaporated Ni electrode. No

change was observed for the coefficients. It is not known whether or

not the adhesion of the brass shim is adequate enough to effectively

clamp the PVF2

.

An attempt was made to simulate the mechanical rigidity of a thick

metal electrode by placing a speciman in a ring collar which held the

speciman fixed at the perimeter of the ring. Measurements on those

specimens with the collar in place were found to be approximately 10%

higher than those without the collar. It has been suggested that the

time scale of the experiment is too slow and these collared specimens

relax before the effect can be observed.

A series of specimens with evaporated aluminum electrodes of 0

various^thicknesses were prepared. The thickness range from 4000 A to

32,000 A. Measurements of the piezo- and pyroelectric coefficients

showed no significant differences for this series of specimens.

At this time specimens are being prepared with evaporated Ni

o o electrodes at 5000 A and 10,000 A thickness. Although these electrodes

can not be called "thick", the amount of deposited metal may be enough

to produce the expected effect of enhanced response due to electrode

rigidity.

152
ASTM Activities

W. P. Harris

ASTM Committee D-9 met three times in this period:

October 17-19, 1978, in New Orleans

March 19-21, 1979, in Cincinnati

June 1 8—20 , 1979, in Philadelphia

Mr. Harris, Chairman of D-9 and of its Executive Subcommittee,

attended and chaired these meetings, and also took part in the activities of several of the subcommittees.

At each meeting 20-30 standards were balloted for revision or reapproval. The Committee had been working hard to bring all its

standards into conformity with the "Blue Book" by including a section on sampling as required. However, as a result of a special conference on revision of the "Blue Book" held at ASTM headquarters in Philadelphia in

September 1978 (attended by Mr. Harris), it was decided to relax the

requirement, as applied to test methods. The revised "Blue Book" is

expected to appear in October 1979, with the section on sampling no longer mandatory for test methods. Because of this, D-9 is no longer

automatically inserting a sampling section, but is looking at each

document to see if such a section would be helpful, or whether reference

to standards on sampling can suffice. Committee D-9 has prepared such

a general standard, D 3636, "Sampling and Judging Quality of Solid

Electrical Insulating Materials," with sampling tables adapted from

MILSTD-105D.

During this period the following new standards prepared by D-9 were

approved by the Society and issued:

D 3638 "Standard Test Method for Comparative Tracking Index of

Electrical Insulating Materials"

D 3755 "Standard Test Method for Dielectric Breakdown Voltage

and Dielectric Strength of Solid Electrical Insulating

Materials Under Direct-Voltage Stress"

D 3756 "Standard Test Method for Evaluation of Resistance to

Electrical Diverging Fields"

Mr. Harris attended the Biennial Conference for ASTM Technical

Committee officers in Philadelphia in September 1978. Several problems

were addressed, including that of getting increased participation in

Technical Committees. As a result of this meeting, Headquarters is

preparing promotional letters to send to selected lists of prospects.

One of the first to be scheduled is one for D-9, to be sent to persons

who purchase Parts 39 or 40 of the Book of Standards, but are not

members. Mr. Harris participated in the preparation of the letter, and

it is now in the process of being printed and sent.

153
Subcommittee 91 on International Standards continues to be very

active. 0-9 shared support of several delegates to TC-15's meetings in

Zurich, Switzerland, in April 1979. Inflation has so increased the

cost of such support that the D-9 Fund is nearly depleted. Two steps

were taken to alleviate the problem. First, Mr. Harris prepared and

sent a follow-up letter asking those who hadn't contributed to the D-9

Fund for 1978-79 to please consider doing so now. Second, the Executive

Subcommittee decided to ask for $30 per person for the 1979-80 year, up

from $20 last year.

The new section on Electrical Safety formed last year in the S/C

on Electrical Tests has been moved to S/C 94 and broadened to include

all aspects of safety during the making of tests on solid electrical

insulating materials.

Several new standards are in preparation, and a major revision of

one of D-9 1 s most widely-used standards, D-150, is underway.

Space Charge Studies

A_ S. DeReggi and M. G. Broadhurst

The thermal pulse method of measuring the distribution of charge or polarization across the thickness of dielectric films continues to be

relevant to advancing our understanding of space charge phenomena in

polymers and the electrical properties of polymers in general. Evolutionary improvements in the data processing and in the data analysis

methodology have been made recently and new results on PVF have been

obtained in collaboration with Dr. Sidney Lang of the Ben Gurion University of the Negev (Israel) who was a guest worker at NBS for two months.

In addition, survey measurements of charging phenomena in non-pol ar polymers have begun.

Previous theoretical work at NBS showed that the information which

can be obtained unambiguously from thermal pulse data consists of

Fourier coefficients of the charge or polarization distribution. However, the diffusive nature of the thermal conduction process results in

unfavorable conditions for recovering a large number of Fourier coefficients, particularly if the charge distribution is concentrated at a depth removed from the thermally pulsed surface. To offset this disadvantage, a first-rate data acquisition scheme including signal averaging

for the enhancement of the signal-to-noise ratio is required. In

addition, carefully programmed numerical computations are needed as part

of the data analysis if all the information contained in the data is to

be extracted. During the past several months, the existing data acquisition system has been interfaced to an Interdata minicomputer in the

Division. Programming to handle the data stream is complete. Programming to extract information about charge and polarization distributions

on the Interdata is currently underway. During Sidney Lang's visit and

thereafter, curve fitting programs were written and run in the NBS

154
computer to interpret qualitatively new data on PV.F in terms of adjustable parameters including the effective depth and width of the polarization. It was confirmed that during the initial stages of poling,

polarization first becomes significant towards the poling cathode, in

contrast to the situation of PVE2 where polarization first tends to

concentrate towards the poling anode. The two types of behavior

strongly suggest effects due to space charge of opposite signs in the

two polymers. It was also found that polarization grows and spreads

while the poling voltage is progressively increased. Ihis work is

currently being prepared for publication. Ihermal pulse measurements of

a survey nature have also been performed on charged non-pol ar polymers

including polyethylene and polytetrafluoroethylene, which are two

commonly used materials in the electrical power industry. Charging was

accomplished by subjecting samples for a period of time to an applied

voltage at various temperatures. Ihe preliminary results have indicated

that charging occurs and that the sign of the charge depends on the

electrode material as well as other parameters. Systematic data are

being developed for a range of metal /polymer interfaces and for a range

of charging voltage and temperature. An attempt is being made to

understand the charging data in terms of a simple picture where a polymer can act as a donor or acceptor of electrons depending on the

properties on the metal/polymer interface. In the case of 30 pm thick

PE charged at 80 °C using a charging voltage of 1750 V and a charging

time of 90 minutes, it was found that as the electrode material (anode

side/cathode side) was changed from Al/Al, Au/Al , Al/Au, Au/Au the

signs and amplitudes of the thermal pulse responses changed. Ihese

results suggest that PE was an acceptor relative to A1 and a donor

relative to Au. Some aspects of this research seem directly pertinent

to the insulation problem in electric power cables. In particular, it

is relevant to ask whether a particular combination of polymer, or polymer blend, and metal electrode could be found which is resistant to

space charge accumulation and hence minimize the space charge enhancement

of local fields in the polymer. Ihis space charge enhancement is one

probable cause of aging and failure of cable insulation.

Piezoelectric Polymer Euzinq

S. C. Roth, A. S. DeReggi , and S. Edelman

Ihis project is sponsored by the U. S. Army Armament Research and

Development Command. It developed from previous work by NBS in cooperation with Erankford Arsenal reported in NBSIR 75-724 (R). NBS is to

assist ARRADCQM to determine the feasibility of using piezoelectric

polymer film in impact sensors for fuzing applications in several

particular geometries.

Two male forms have been built to facilitate mounting an irregularly shaped polymer sensor inside the ogives (forward part of the

casing) of selected projectiles. Ihe two forms built so far differ

slightly in the length of the forward sections. Ihe machining of the

155
forms was done by numerical control and the directions were preserved

on tape so that additional modified forms can be constructed with a minimum of additional design.

Six pre-prototype polymer sensors were designed, constructed, and

delivered to ARRADCOM. After some minor modifications and testing at

ARRADCOM, they are to be subjected to reverse ballistic tests in an air

gun at HDL.

Some preliminary tests have been performed on our drop tester to

study the effect of impacts of limited area on the output of large area

(several wavelengths) sensors fixed to metal backing.

Structure and Performance of Piezoelectric Polymers

G. T. Davis and M. G. Broadhurst

The objectives of this task are to study the molecular motions,

structural changes, and electrical properties associated with the

process whereby polymers are made piezoelectric. Information gained

from these studies will be used to optimize piezoelectric and pyroelectric response with respect to both initial activity and long-term

stability.

Although the best piezoelectric and pyroelectric activity from

polymers is still less than that from good ceramic materials, the other

properties of polymers often made them the preferred transducer material.

Some of the polymer properties which made 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 17

papers presented at the American Physical Society meeting in March 1979.

In principle, any polar polymer can be made piezoelectric by

preferentially aligning its dipoles in an applied electric field while

in the liquid phase, then freezing in the alignment by cooling below

the glass transition before removing the electric field. Practical use requires that T^ be greater than ambient temperature but amorphous

polymers have other limitations in that the degree of alignment (polarization = net dipole moment/unit volume) is only weakly linear with

applied field, and the electric fields that can be applied are limited

by rather low electrical breakdown strengths above T . The polymer of

primary interest continues to be poly(vinyl idene fluoride) in which the

polarization resides in the crystalline phases of the polymer and the

polarization attainable is an order of magnitude larger than that of

typical amorphous polymers.

156
The model developed here for piezoelectric and pyroelectric

response from a polymer composed of this lamellar crystals with preferentially aligned dipoles dispersed in a randomly oriented amorphous

matrix was published in J. Appl. Phys. 49, 4992 (1978). Data relating

piezoelectric and pyroelectric response to measured polarization using

the expressions developed from the model were submitted to ONR as technical report number 11 and have been submitted to the Journal of Applied

Physics. The data obtained indicated that the polarization charge was

compensated by real charge at the external electrodes rather than at

the crystal-! i quid interfaces throughout the polarmer film. Further

evidence for this conclusion was obtained from measurements on a thick

(0.13 mm) specimen of PVDF supplied by EMI of Great Britain. The ratio

of piezoelectric to pyroelectric response for this sample was about two

times larger than usually observed which was traced to the fact that

the film had many tiny voids and was therefore more compressible than

solid material while thermal expansion properties were unaltered. The

enhanced effect of voids could be expected only if the polarization is

compensated externally.

A cooperative model has been developed to describe ferroelectric

polarization in polyvinyl i dene fluoride (PVDF). The molecular dipoles

within the crystal are assumed to have two or more orientations available to them and the lattice energy of a given orientational site is

assumed to be proportional to the fraction of molecules having that

orientation. An analytical solution was obtained for the 2-site model

which predicts polarization hysteresis typical of ferroelectrics.

However, a more complex 6-site model, which can be analyzed numerically

was needed to account for observed infrared hysteresis data and electric-field-induced x-ray structural changes. Although the model is

simple, rather complex behavior is observed including a gradual increase

or decrease in the remnant polarization with number of cycles of electric field application. Though the agreements with various experimental

data are good, an obvious need to include kinetic effects in the model was indicated. These results have been communicated to ONR as technical

report number 13 and submitted to the Conference on Electrical Insulation and Dielectric Phenomena.

All the available data indicate that only about 50% of the maximum

polarization that can be expected in PVDF has actually been achieved.

This is probably due to the incomplete alignment of dipoles in the

electric field. A study of the effect of crystal orientation on poling

has been initiated using x-ray diffraction. A Phillips diffractometer

has been modified so that a polymer film can be oriented at any position

in the beam and a transmission scan obtained. The electric-fieldinduced phase transitions from alpha to the polar alpha phase and then

to beta phase which were reported here last year are particularly

useful for this investigation. This phase transition from a to polar-a

results in the loss of 100 and 120 peaks while increasing the intensity

of the 200 peak.
Conversion to the beta phase at still higher fields results in even greater changes in the diffraction peaks. After several unsuccessful

attempts to apply high electric-fields to PVDF samples in the alpha

phase which were obtained from suppliers in that form, we resorted to

melting the mixed phase biaxial ly oriented films and stretched them at

high temperature to obtain uniaxial ly oriented alpha films. These

samples still withstand electric fields in excess of 2 MV/cm.

A fourth crystal form of PVDF has been reported. It is thought to

have a tttgtttg' chain conformation and is also thought to crystallize

in a polar unit cell. We have confirmed literature reports that annealing through the melting point of alpha phase in the presence of a polymeric surface active agent results in complete conversion to this

gamma phase. The poling characteristics of unoriented films of gamma

phase PVDF are now being investigated.

An important aspect of piezoelectricity in PVDF which requires much

further investigation is the mechanism through which the polymer gradually loses its electrical activity at elevated temperatures. Future

work will be directed toward determining the parameters that most

affect the thermal stability. The influence of the initial crystal

phase on the ultimate stability will be an important part of this

study.

Polymer Sensors for NDE of Bearings

S. C. Roth, S. Edelman, J. F. Mayo-Wells, and J. M. Kenney

The 1979 NDE work of the Bulk Properties group consisted of a comparison of the usefulness of polymer sensors and conventional accelerometers for monitoring the condition of bearings. The study led to

the publication of a paper in the Proceedings of the 28th Meeting of the

Mechanical Failures Prevention Group, NBS Special Publication 547,

pp. 303-314, July 1979.

The study used a horizontal shaft supported on ball-bearings, a quiet bearing at one end and a noisy bearing at the other. An isolated

electric motor was coupled to the shaft by a flexible belt so that only

the bearings contributed measurable noise to the structure supporting

the shaft. A polymer sensor was fixed to the stationary race of eacn bearing and a miniature piezoelectric accelerometer was mounted on the

supporting structure as close to each bearing as practicable.

It was found that polymer sensors have several advantages. The

principal advantage derives from the flexibility and low density that

allow the polymer sensor to be mounted directly to the bearing. So

mounted, it responds only to the bearing noises. Conventional accelerometers are relatively massive and require specially prepared mounting

surfaces of appreciable area. These characteristics require them to be

mounted some distance from the bearing where they can be unaffected by

noise from other sources. The extraneous noise can cause uncertainty as to which of several bearings is bad.

158
It has been suggested that polymer sensors can provide a noninvasive means for detecting cracks of the kind affecting DC-10 airplanes

recently. A polymer gauge cemented to a metal surface responds to surface strain in all directions and detects a signal which can be analyzed

into a spectrum of resonances of the metal panel. A change in the

structure of the metal preliminary to cracking and certainly development

of a crack will cause a significant shift in resonance frequencies and

amplitudes. Polymer sensors are cheap so that one can be attached to

each critical surface. The sensor and lead constitute a continuous thin

sheet of polymer that would not affect the behavior of the panel. All

resonances of the panel would be excited any time the engines were

operating. Before each takeoff, a superposition of the current spectrum

would detect any change in the integrity of the panel.

Other proposed NDE work consists of the use of polymer sensors to

detect broken strands in airplane control cables and the use of polymer

sensors in a non-resonant method to measure the real and imaginary parts

of the elastic moduli of long, thin rods as continuous functions of

frequency and static load.

Polymer Stress Gauge for Intaglio Printing Press

S. C. Roth, J. M. Kenney, A. S. DeReggi , and S. Edelman

This work, which is supported by the Bureau of Engraving and Printing, U. S. Department of the Treasury, involves the development of a gauge to measure the dynamic pressure at critical points in the presses

used to print money. It is the continuation of work reported last year.

The first phase of the work was completed this year. The accomplishments of the first phase included measurement of the width of the

area of contact between the two cylinders of the press, 18.7 millimeters,

the duration of contact of a point on the upper cylinder with the lower

cylinder, 0.25 milliseconds, and a qualitative (uncalibrated) determination of the change of the pressure with time during contact. The suc- cessful measurement was made with a gauge having an active area two

millimeters wide and 14 centimeters long with very narrow inert shoulders. The electrodes were evaporated indium about one micrometer thick.

The gauge was mounted directly on the steel cylinder of the upper drum

of the press below all of the layers of paper and rubberized canvas used

to distribute the printing pressure.

The work of the first phase was described in a report to BEP and in

a paper by the authors listed above which was presented to the 10th

Annual Symposium of the Paper and Pulp Foundation at Miami University,

Oxford, Ohio.

159
Piezoelectric Polymer Deposition

S. C. Roth, S. Edelman, and M. G. Broadhurst

This project is sponsored by the U. S. Army Research Office. It is

a continuation of work described in the previous annual report.

Fused powder films were formed of PVDF-TFE copolymer by fusing a coating of electrostatically-charged, spray-deposited, polymer powder on

a metal substrate. Subsequent attempts at poling such films were only

marginally successful. Attempts to use the same procedures, which might

be expected to give greater piezoelectric activity, resulted in films of uneven appearance, apparently caused by incomplete fusing. Attempts to

form smoother films depend on procurement of PVDF powder of low molecular weight.

In order to produce films with better mechanical properties and to

pole them so that they exhibit satisfactory piezoelectric activity, it

is necessary to have a better understanding of the mechanisms involved.

However, the detailed physics of piezoelectricity in polymers is still

controversial to some extent. Also, on a different scale of magnitude,

the mechanical and dielectric properties of fused and incompletely fused

films are not well-known. Available experimental data on piezoelectric

polymers consists of measurements made on samples prepared in various

ways and performed on different samples by a number of different methods

under different conditions. The properties of piezoelectric polymers

are more dependent on history and treatment than those of crystals and

ceramics. As a means of accumulating data which would form the basis of

theory to provide the guidance needed for this project, a set of measurements was worked out which yield all of the pertinent mechanical, dielectric, and piezoelectric properties of a polymer sample. The measurements

are made in a short time under uniform conditions. The necessary apparatus

has been built or assembled, a pair of capacitance bridges has been

calibrated and each has been shown to have adequate sensitivity. Apparatus for measuring suitable small displacements by a microphone with a film micrometer eyepiece illuminated by straposcopic light synchronized

with the motion of the sample has been provided.

Development of Piezoelectric Polymer Stress Gauges for Rock Studies

S. C. Roth and 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.

Most of the gauges having single circular active areas were delivered

early in this fiscal year. These gauges were similar to those developed

for the National Highway Traffic Safety Administration (described in

NBSIR 76-1078). Three sizes of active area were built: 5, 3.5, and

160
1 cm, respectively. These, especially the one centimeter size, have

been effective in detecting and measuring the acoustic emission from

rock samples under stress. Also, they have been found to survive

collapse and crushing of the rock specimens unless a crack develops

directly across the active area.

Considerable difficulty was experienced in designing and building

the masks for a 16-element array. This has been successfully accomplished; twelve of the arrays have been built; one has been delivered to

the Bureau of Mines; and the remainder of the contracted number of

gauges will be delivered before the end of the fiscal year. Future work

on rock and soil transducers is expected to result from tests on these

transducers.

Automated Dielectric Measurements

F. I. Mopsik, S. J. Kryder, and 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 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 speech than previously possible.

Work completed in FY 1979 includes a step function generator that

can put out simultaneous positive and negative steps of 100 V matched to one part in 10 s with a 10 ps rise time. This matching is necessary to

accurately subtract out the constant capacitance term. A detector has

been completed and is being trimmed. This detector will be able to

resolve charge changes to 0.1 pC with a 10 ms response time. These and

previously completed or obtained components complete the instrumentation.

One other needed piece of support work that has been completed is

the development of an efficient numerical Laplace transform technique.

The transform gives accurate results over six decades in log time and uses 36 preselected data samples. This performance is quite superior to

methods in the literature.

The recording of data for the thermal pulse experiment and the

transfer of these data to the Interdata Laboratory computer has been

completed and work has started on writing the needed programs for data

analysis. When completed this automation will provide a convenient

method of determining polarization distributions in polymer films as an aid to studying their piezoelectric and charge transfer properties.

161
Ultrasonic Hydrophone

A. S. DeReggi , S. C. Roth, J. M. Kenney, and S. Edelman

This project is sponsored by the Bureau of Radiological Health

which is also contributing the service of a guest worker. The early

work was described in the annual report for last year.

The 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.

During this year, a number of prototype hydrophones were built and

tested at NBS and at the Bureau of Radiological Health. The hydrophone

is a taut membrane of polyvinyl idene fluoride (PVDF), 50 pm thick, with

a piezoelectrical ly active central spot of about one millimeter diameter

The close impedance match of PVDF to water makes the hydrophone acoustically transparent in use. Thus, whether the hydrophone is held stationary or is scanned across the field, the acoustic impedance presented

to the source is essentially the same as it should be if the probe were

not present. The response of the probe is flat between 0.5 and 10 MHz.

The thickness resonance is about 20 MHz.

The hydrophone was described in a paper presented by the authors

listed above and G. Harris of the Bureau of Radiological Health at the

joint meeting of the Acoustical Society of America and the Acoustical

Society of Japan, November 27-December 1, 1978. J. Acoust. Soc. Am.,

64, S. 55 (1978).

Plans are currently under way to extend the work to linear arrays,

planar arrays to two-dimensional arrays conformed to special shapes such

as parabolic dishes. These arrays are of interest in medical imaging

systems.

Fabrication of Piezoelectric Polymer Film

A. J. Bur, J. M. Kenney, and M. G. Broadhurst

The Department of the Navy is supporting a project to fabricate

piezoelectrical ly active PVF2 specimens with thicknesses of 0.81 mm

(32 mil). A thick transducer is described because, relative to the thin

film PVF 2 transducers which we have routinely prepared, a thick transducer will have a lower capacitance and a correspondingly higher voltage

response for a given strain. A relatively large voltage response is the

benefit of fabricating a thick transducer.

162
Ihe problem in preparing thick transducer specimens is that the

dielectric strength of the specimen is usually lower than that of a thin

film of the same cross section. A commercially available thick film was

found to have such a low dielectric strength that the minimum poling

field of 800 kV/mm could not be reached. Consequently, we began to

prepare thick specimens from PV.F2 powder starting material. Ihe planned

fabrication procedure will be: (1) vacuum molding of bubble-free disked

shaped specimens; (2) converting the PVF2 crystal structure from a to p

phase by tensile extension or by rolling* (3j evaporating electrodes;

(4) poling at 800 kV./cm or higher at 80 6

C. At this time, bubble-free

disk shaped specimens have been prepared but poling has not been carried

out.

163
POLYMER STANDARDS FOR CONTROL AND EQUITY

Molecular weight and molecular weight distributions are the most

important determinants of the useful properties of high polymers. They

are of primary importance in determining both the processability of the

raw materials and the characteristics of the fabricated products. Directly or indirectly, molecular weight is an important part of the

specifications used in the commerce involving the tens of millions of

tons of plastics produced every year. The ability to determine molecular weight reliably and reproducibly in different laboratories is thus

important to both plastics producers and fabricators.

This task has four main technical activities, all aimed at this

overall objective of providing a reliable base for the measurement system of molecular properties for use in commerce. First, the current

needs of the measurement system used in industry are addressed by projects on the production of standards for molecular weight calibration

and research on methods of improving the utilization of gel permeation

or size exclusion chromatography which has become a widely used industrial measurement technique. Classical absolute molecular weight determinations are highly labor intensive, which limits the speed of

standard reference material production and consumes large amounts of

capital per standard. Our highest priority is therefore placed on the

development of an absolute molecular weight detector for a gel permeation chromatograph which will be able to produce standards at a much

faster rate without a sacrifice in quality. Elastomer SRM's are produced for quality control and specification by the rubber industry. The

second technical activity provides the scientific basis for the molecular characterization methods of the future by exploring techniques

and theories which meet needs we see growing in the plastics industry.

Examples of this are our projects concerned with block copolymers and

blends which are rapidly growing segments of total plastics use. The

third and fourth activities involve the development and application of

molecular characterization methods to particularly critical plastics applications where market forces are not sufficient to attract sufficient

industrial effort. Our present work in these activities relates to the

use of ultra high molecular weight polyethylene for orthopedic implant

use and the development and application of gas permeation measurement

methods and standards.

Technical Activity

Self-calibrating Gel Permeation Chromatography

P. H. Verdi er

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 mo- lecular 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

164
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 re- quired 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 and the results extrapolated

to zero 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 mo- lecular 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.

During the current fiscal year, we have completed construction of a prototype of the scattering cell and its mounting, the two most critical

components of the instrument. In the coming fiscal year we expect to

complete design and construction of the remainder of the instrument and

to begin testing it.

Recycle Gel Permeation Chromatography

F. L McCrackin and H. L. Wagner

Recycle gel permeation chromatography (GPC, also called size ex- clusion chromatography) was studied theoretically and experimentally as

a method to measure the column spreading parameter and the polydispersity of nearly monodisperse polymer standards. The width of the

recycled chromatograms could be accounted for by four causes: (1) the

volume of solution injected into the column, (2) the column spreading,

(3) the molecular weight distribution of the polymer, and (4) spreading

due to the pump. A method was developed to separate the spreading into

contributions due to each of the individual causes. Previous analysis

of recycled GPC considered the width of the chromatograms as due to only

the column spreading and molecular weight distribution of the polymer.

By taking the other contributions of the spreading of the chromatograms

into account, much more accurate values of the column spreading parameter and polydispersity of the polymer are obtained.

165
The recycle experiments were carried out with a set of cross linked

polystyrene columns of nominal pore size of 10 3

, 104

, 10 s and 106 A in

a GPC system with a differential refractometer as a detector. The

columns were calibrated in tetrahydrofuran and toluene with 5 narrow

distribution anionic polystyrenes ranging in molecular weight from 9,000

to 498,000, including SRM 1478 at 36,000 and SRM 705 at 175,000.

To reduce the extent of interference by spurious peaks, which

normally occur at high retention volumes after the polymer peak has

eluted with distortion of the subsequent recycle peaks, most recent runs were made in toluene. The use of this solvent, together with additional

changes in the injection procedure, reduced this interference but did

not eliminate it entirely.

Previously, all the various components of spreading were obtained

by a least squares fitting of a function of the total spreading to a polynomial in the number of cycles. To improve the precision of the

results, we made use of the observation that the spreading due to the

injection and the pump was the same for all the samples. These two

components of the spreading were then determined separately by measuring

the spreading with the columns removed from the chromatograph. Knowing

these, it was possible to determine the remaining components, the column

spreading and polydispersity, from a least squares fitting of a function

of the total spreading to a simple linear relationship in the number of

cycles.

Results from this analysis are shown in Table 1. The polydispersities, M /M of the anionic polystyrenes are quite low, ranging from

W 1

1

1.0027 to 1.09. The spreading due to the columns increases with mo- lecular weight from 0.2 ml at a molecular weight of IQ 4 to 0.6 ml at a molecular weight of 2 x 10 s

.

Such measurements now allow the spreading to be measured for any

set of columns without using recycle by measuring SRM 750 or 1478.

A chromatogram is obtained for one of these polystyrenes run through

the columns, and the spreading due to the columns is then found by subtracting the spreading due to the known polydispersity from the total

spreading.

166
Table 1

Polydispersities and Column Spreading Parameters

for Polystyrene Samples

Sample Solvent M x

10‘ 3 VM

n

Spreading

Parameter, ml

SRM 1477 Toluene 9.1 1.124 0.259

SRM 1477 THF 9.1 1.050 0.158

SRM 1478 Toluene 36 1.0095 0.395

ii ii ii 1.0099 0.436

ii ii ii 1.0091 0.437

n THF ii 1.0090 0.394

PC25170 Toluene 51 1.0028 0.336

PC4b Toluene 111 1.0030 0.581

n ti ii 1 . 0043 0.449

SRM 705 Tol uene 175 1.0062 0.592

ii THF ii 1.0090 0.505

PC50124 Tol uene 233 1 . 0028 0.551

PC3b Toluene 390 1 . 0027 0.538

167
Standard Reference Materials for Rubber and Rubber Compounding

G. W. Bullman and G. B. McKenna

Many of the procedures used by industry for quality control and

commercial specifications of rubber depend on standard reference materials (SRM) which are maintained by the Polymer Science and Standards

Division. This project renews SRM's as stocks are depleted and produces

new SRM's needed by industry for control of processes and commercial

specifications which are outside the range of properties available with

current SRM 1 s.

The limited resources of the SRM program have prompted us to try to

elicit support for an industrial research associate program that would

assist in the maintenance of the current program and in the development

of new SRM's. Although ASTM Committee D— 1 1 on Rubber and Rubberlike

Materials has set up a task group to try to get support for the rubber

SRM program from the rubber industry, nothing has been accomplished in

this regard since December 1977 and the industry appears content to let

the rubber SRM program remain static. In response to this, the Polymer

Science and Standards Division has been making efforts tc maintain the

important SRM's and to eliminate those which are selling at very low

levels. The net result will be a streamlined rubber SRM program which

serves industry in an efficient manner with materials which are certified by NBS to have certain physical and/or chemical properties rather

than having NBS serve as a warehousing distributor for industrial grade

material s.

As part of the program to maintain the current important SRM's, we

have contracted for the production of a new Butyl Rubber SRM, which will

be certified for Mooney Viscosity. In addition, one material, N-tbutyl-2-benzothiozole sulfenamide, a rubber accelerator, will be renewed

as an SRM. This material is certified only for homogeneity and fits

into the category of warehousing an industrial grade material, but will

be renewed to avoid a major disruption in the ASTM standards which rely

on this material.

Work within ASTM has also indicated a requirement for a high temperature, high viscosity, Mooney Viscosity reference material. Work

will be undertaken to develop such a material during the coming year.

Quasielastic Light Scattering

C. C. Han

Quasi elastic light scattering uses the photon correlation technique

to measure the two time correlation function of scattered light from

polymer solutions. This two time correlation function at any momentum

transfer, q, is related to the intermediate scattering function, S(q,t),

which in turn is a double Fourier transform of the space and time cor168
relation 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 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 interpretation of quasi elastic 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

A. Z. Akcasu 1 and M. Benmouna 1

University of Michigan

Interpretation of dynamic scattering experiments require,

ideally, a theory that can predict the intermediate scattering function,

S, as a function of t and q, under actual experimental conditions, which

are characterized by the temperature and concentration of the solution,

and by a chain model consistent with the chemical structure of the

polymer. Unfortunately, exact expressions of S(q,t) are available, at

present, only for a single unperturbed (8-condition) gaussian chain

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 express S(q,t) of

both linear and circular chains for Rouse and Rouse-Zimm cases for

infinite chain limit in a closed form. Also we can express S(q,t) for

finite chain lengths of linear chains in the Rouse limit and for circular chains in both Rouse and Rouse-Zimm limits in a 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

Q(q) = -lim

t + 0

dt

can be calculated. The temperature and concentration dependence of Q(q)

in terms of the “blob model" chain statistics can be calculated not only

for the intermediate scaling region but also for the upper and lower

169
transition region where information about polymer chain parameters such

as radius of gyration, Rq, statistical length, a, and hydrodynamic

interaction, B, can be extracted.

Iemperature and Molecular Weight Dependence of Polymer Chain

Dimensions and Application to Intrinsic Viscosity

A. Z. Akcasu 1 University of Michigan

The molecular weight, M , and temperature, I, dependence of

the radius of gyration, Rq, and hydrodynamic radius, R^, of a polymer in

dilute solution have been investigated. Theoretical predictions were

compared with experimental results on polystyrene in various solvents as

a function of M and T, where the lower critical solution temperature is

W

high and has negligible effect 1

. Ihe existing data fell in a^region

where can not be represented by a simple power law, R^ ~ M , whereas

most of data on Rq satisfy Rq ~ M

v

. A power law fit to data would yield

v

1 < v in this region, even though the theory yields v1 = v in the asymptotic region.

The same molecular weight and temperature dependence has also been

successfully applied to intrinsic viscosity2 using the dynamic argument

of Weill and des Cloizeaux. Without any parameters besides the one which has been obtained previously in an Rq measurement, the intrinsic

viscosity of polystyrene in various solvents and temperatures can be

represented over a range of 5 decades as shown in the Figure 1. This

scheme could overcome the difficulty of empirical Mark-Houwink equations

Eq] = KM

a

, which only apply for limited molecular weight ranges and re- quire a different set of parameters (K and a) for different experimental

conditions. Our scheme can be used as a characterization method for

polymers with any desired solvent and temperature. Also, it may provide

a better universal calibration for gel permeation chromatography.

References:

(1) "Molecular Weight and Temperature Dependence of Polymer Dimensions

in Solution," A. Z. Akcasu and C. C. Han. Macromolecules, 12, 276

(1979).

' ~

(2) "Molecular Weight and Temperature Dependence of Intrinsic Viscosity

of Polymer Solutions," C. C. Han, Polymer, (in Press).

Our theoretical predictions of [q 3/Cn

J

q

through the static argument

of Flory-Mandel kern where [q]^ R^ and the dynamic argument of Wei 11 -des

Cloizeaux where [q] * R^ are also shown in solid lines. The discrepancy

with experimental results of the static argument is due of its failure

in differentiating Rq and R^ and in predicting the slower cross-over of

Rq from the 6-region to the good solvent limit. The dotted line represents the limiting slope of [q] at high M and T. 170
irt O

S01 » 3

o; e 01 01 S- >> s- ai 01 r— 3 3 3 o 4-> CO S Q. 03 CO 3 S- 03 O " 01 0) -3

•r- HJ3

a.

S- ZC -M E 3

03 \ 0)O > s: +-> •<— o 3 - 3 s_ *o 2 01

•r- 01 +> OJ to -M 3 O S_ 03

oi 0) cn 3 01O 3 E -r- o +>

01 03 01 01 01 sS- i. S S- £ 3

>, 03 03

O

+> Q. i- ai s- co fC r <3 c

>, CHr— -M Q.-1— 1— C 3 o *i~ a CO >>+J

Q.I— 01 03 r— 3

03 r— 3 ai 0-0 0 i- O £ O CO £ 01 >,T3 CO » ai sS~ 3 3

+J 01 03 01 -M to

•r- 3 i= 03

w CO •>— SI

O CO O) 2 O 3 3-r- E U E 3 O

CO

O 4-> E '—> cu

•rO -I- S cn > s 01 3

03 3 '—

O t— 4-> 4-1 •r- JT v. -a 3

CO +j <3 m- 3 a 3 *T- 1 O (3 =

•r Sh •r— s_ 4-> 01 S-

+-> •> II 3 S_ 0) c ai cn 3 CL

•r- S_

H •I- +J

X 3 01 03 01 0— 4-> "O 2 S- O 03 3

S- 03 S- 'CL 3 C 0) 03 E 01 O CL-'—* !— 0.’ S_

•1- E 3 34 0)

+-> 0) c u <4-

03 -M

—

01 03 4-

•rO i— 4-> -r— s- -o s: C 013

fl c\ E .3 > 03 N 4-> (3 +J 01

oi co s: 3 OI >r 3 +-> +-> 3 3 0) 1— 3 II 4-> s- 01 co -o

13 > H 03 CO 01 CD r— 2T 03 X • r— o \ O -T- U— to 2- 21 C+-
Single Chain Neutron Scattering in Concentrated Solutions and

Melts

A. Z. Akcasu 1

, G. C. Summerfield1

, S. N. Jahshan2, C. Y. Kim3

, and H. Yu3

University of Michigan

2 SUNY, Buffalo

University of Wisconsin

Measurements of the single chain configuration in neutron

scattering have always involved taking the limit of small relative

concentration of the deuterated polymer. This is done to eliminate

interference effects in scattering from different chains. The difficulty with this procedure is, of course, that it emphasizes the least

reliable results, namely those from the small relative concentrations of

labeled polymers.

A general method for extracting the single chain scattering

function by performing experiments at two different concentrations of

labeled chains while keeping the total polymer concentration constant

has been developed. This method has been tested experimentally by using

10,000 molecular weight polyisoprene and matched deuterated polyisoprene

mixtures. Signal to noise ratios so obtained during 40 hour runs at the

NBS facility are excellent and are comparable with results obtained

using the D17 instrument in Grenoble, France, with a two dimensional

detector.

Characterization of Polymers and Domain Structure Study of

Block Copolymers

C. C. Han, D. B. Minor, T. Hashimoto 1

, and I. Noda2

1 Kyoto University, Japan

2 Nagoya University, Japan

Characterization of polymers with different architecture such

as branched star and comb polymers, and stiff chain polymers will be

carried out by small angle neutron scattering. Also, the domain interface structure of linear and star shaped block copolymers will be

studied by SANS. Samples and specimens are currently being prepared and

characterized by conventional techniques.

Excimer Fluorescence in Dilute Solutions of Block Copolymers

F. W. Wang

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 wave172
lengths with respect to the fluorescence spectrum of the isolated molecule. Similarly, excimer formation may take place by intramolecular

processes in polymers carrying excimer- forming groups. Thus, excimer

fluorescence has been observed in dilute solutions of polymers such as polystyrene, polyvinyl naphthalene, and poly(l-naphthyl methacrylate).

Our experiments 1 as well as those of others 2 ’ 3 have shown that in

solutions of polymers carrying excimer-forming groups, excimer formation

becomes more efficient as the polymers become more compact or as the

intermolecular interaction among polymers increases due to aggregation

or an increase in concentration. Therefore, excimer fluorescence may

serve as a probe for conformational change or aggregation taking place

in solution.

We have measured excimer fluorescence in dilute solutions of a polystyrene and of a four-branched block copolymer, each branch of which

has a polystyrene block at the free end and a polybutadiene block at the

branch point. The solvents used were cyclohexane and a mixed solvent

consisting of 5:1 by volume methylene chloride and cyclohexane. As

expected, phenyl -group excimer formation for both polymers was found to

be more efficient in cyclohexane, a poorer solvent for polystyrene, than

in the mixed solvent, a better solvent. But what is more interesting is

this: in both solvents, excimer fluorescence was found to be more

efficient for the block copolymer than for the homopolymer. These

observations suggest that intramolecular or intermolecular aggregation

takes place even in the dilute solutions (about 0.03%) of the block

copolymer.

Additional experiments will be performed to study the variation of

excimer formation with temperature, solvent power, and the number of

branches. Experiments based on the fluorescence energy transfer technique are being made to determine whether the aggregation is intermolecular or intramolecular and whether intermingling of the polystyrene

block and the polybutadiene block takes place.

References:

(1) F. W. Wang and R. A. Velapoldi, unpublished results.

(2) T. Nishihara and M. Kaneko, Makromol. Chem. , 124 , 84 (1969).

(3) A. C. Somersall and J. E. Guillet, Macromolecules, 6, 218 (1973).

Fluorescence Energy Transfer Technique for the Study of Polymer

Compatibi 1 ity

F. W. Wang and R. E. Lowry

There has been growing interest in the potential value of reusing

scrap plastics as blends of generic mixtures. Because such blends often

have very poor mechanical properties, there have been some efforts to

173
develop additives or "compatibil izers" which can improve the properties

of the blends. Since a convenient technique is needed to test polymer

compatibility, we have initiated a program to evaluate the utility of

the fluorescence energy transfer technique for the study of polymer

compatibility.

Fluorescence energy transfer can take place between a fluorescence

energy donor and a suitable energy acceptor over distances as large as

o 70 A. Since the efficiency of transfer depends on the inverse sixth

power of the distance between ther donor and the acceptor, in a blend

containing two polymers labeled with donor and acceptor, respectively,

the efficiency of transfer will be small if the two polymers are incompatible and segregated but will be large if they are compatible and form

a single phase. Some results of our energy transfer measurements to

evaluate the effectiveness of a compatibil izer are described as follows:

Although poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) are incompatible 1

, Kwei and co-workers 2 found it possible to render these two methacrylate polymers compatible with the use

of po ly (vi ny 1 idene fluoride) (PVF 2 ) as "compatibilizer" or a common

solvent. We prepared methacrylate polymers labeled with donor or acceptor. The efficiencies of energy transfer in three polymer blends

with the following components were determined: 1) donor-labeled

poly(ethyl methacrylate) polymer(D-PEMA)/acceptor-labeled poly(methyl

methacrylate) polymer (A- PMMA) ; 2) D-PEMA/A-PMMA/PVF2 ; and 3) D-PMMA/APMMA. It was found that, at the compositions studied, the efficiency of

energy transfer for the second blend with PVF 2 was close to that for the

third which should be homogeneous, while the efficiency for the first

blend without PVF 2 was much lower. Thus, in agreement with calorimetry

results 2

, energy transfer measurements showed that, at some compositions, PVF 2 serves as a compatibilizer for the two methacrylate polymers.

To establish the utility of the fluorescence energy transfer technique for the study of polymer compatibility, we plan to investigate

some well understood polymer blends by this technique and compare the

results with those from more conventional techniques.

References:

(1) L. J. Hughes and G. E. Britt, J. Appl. Polym. Sci., 5, 337 (1961).

(2) T. K. Kwei, H. L. Frisch, W. Radigan, and S. Vogel, Macromolecules,

10, 157 (1977).

174
Statistical Mechanics of a Generalized Lattice Model: A Model

for Interacting Polymer Molecules

D. H. Lohse 1 and I. C. Sanchez

1 NRC-NAC Postdoctoral Associate

We have considered the statistical mechanics of N indistinguishable

particles distributed on a lattice of uu sites. The model is a generalization of the usual lattice model in the sense that up to m particles

can be accomodated at each lattice, site. The potential energy E of the

system is assumed to be given by

m

E = X] uun^n

n=0

where w

n is the number of lattice sites (cells) containing n particles

and E

n is the potential energy of a cell containing n particles.

In the thermodynamic limit (N, uu ®, nAu = constant) the canonical

partition function can be evaluated exactly for this model. Some interesting properties of this model include:

1) No first order phase transition is possible.

2) For m = 1, or equivalently, m > 1, E2 = E2 = . . . = Em ^ + ®,

the free energy is that of a lattice gas without attractive

interactions and the distribution law for cell occupancy cor

responds to Fermi-Dirac statistics.

3) For m = N, E n = ne, a Bose-Einstei n distribution law is

obtained for cell occupancy.

4) For finite m(m ^ 2) and E

n = ns an intermediate distribution

law is obtained.

The above assumption that the potential energy of the system is

equal to the sum of cell energies is in general invalid for^ interacti ng

particles. However, there exists a class of intermolecular potentials

for which this assumption is correct. This important result is expressed

in the following theorem which we state without proof:

Theorem

Consider a system of N spherical particles of diameter d whose

potential energy is pairwise additive. The system is divided into a lattice of uu cells each of volume (tt/ 6 )

d

3

. A system configuration in

which all N sphere centers are at lattice positions is defined as a lattice configuration. Any system configuration can be converted to a

175
lattice configuration by translating all spheres which are located at

off-lattice positions to the centers of their respective cells. If the

pair potential p(R) between spheres separated by a distance R is

proportional to the covolume (the common volume), i.e., if

p

0

(l - R/d) 2

( 1 + R/2d) R < d

m(R) =

0 R £ d

then the mean potential energy of the system <E> is equal

potential energy of the translated lattice system, <E>

to

lattice’

the mean

with

< ^> lattice m<

^n>

< F > - ^o <n(n - 1)>

n 2

where E

n is the energy of a cell containing n spheres with n(n - l)/2

pair interactions. A corollary to this theorem is that the mean value

of the total covolume is the same in the lattice system as in the non- lattice system. The process of translating the N spheres to their

respective cell centers does not alter the mean value of the total

covolume. It is this isomorphic property that makes this lattice model

so valuable for treating polymer-polymer interactions. The simplest

representation of a polymer molecule is that of a spherical particle of

uniform (and very low) monomer density. Thus, when two polymer domains

overlap the number of intermolecular monomer-monomer interactions will

be proprotional to the covolume.

The utilization of this model will enable us to predict the affects

of polymer concentration on chain dimensions.

Phase Transition Behavior of the Isolated Polymer Chain

• I. C. Sanchez

A mean field theory of chain dimensions has been formulated which

is very similar to the van der Waals theory of a fluid. In the limit of

infinite chain length, the chain undergoes a Landau type second-order

phase transition. At low temperatures the chain is in a condensed state

and the mean square gyration radius <S 2 > varies r where r is proportional to chain length. At high temperatures the chain is in a gas-like

or coil state where <S 2 > varies as r^. In the condensed state fluctua

tions in <$ 2 > are very small (or order unity) whereas they are very

large (of order r) in the coiled state. A characteristic feature of the

176
theory is that ternary and higher order intramolecular interactions are

approximated. At high temperatures only binary interactions are important, but at low temperatures many of the higher order terms contribute.

An important conclusion of this study is that a polymer chain does not

obey ideal chain statistics at the 6 temperature. Although the second

virial coefficient vanishes at 0, the third virial coefficient does not;

its presence is responsible for the perturbation of the chain statistics.

For an infinite chain, 0 and the second-order phase transition temperature are identical. When generalized to d-di mens ions the theory yields

at low temperatures, <S2 > a/4 ~ r for all d, and at high temperatures,

<S2 > ~ r6/( d +

ancj < 52 > r , d > 4.

Dynamics of Polymer Chains

P. H. Verdier and D. E. Kranbuehl

The dynamical 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 cal i brants of

known molecular weight is required. Improvements in the theory could

reduce or even remove the need for cal i brants, allowing the determination of molecular weight distribution of polymers for which cal i brants

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

present theory is its inability to treat chain entanglements in a realistic way. Our present work is aimed primarily at the study of en- tanglement 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

177
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. This work

has just been published. During the current fiscal year we have carried

out a series of studies of the effects upon relaxation behavior of the

type of lattice employed. Preliminary results suggest that selfentanglement effects are somewhat weaker on face-centered and bodycentered cubic lattices than on the simple cubic lattices employed in our earlier work, though still much stronger than the current theoretical predictions. We expect to complete this work early next year.

Additional work planned for the coming year will proceed along

three lines. First, there is at present an unresolved disagreement in

the literature regarding the interpretation of the time-correlation

functions obtained for flexible chain molecules in the quasi -elastic

light scattering experiment. It is not clear whether these functions

exhibit the entire spectrum of chain relaxation times or are dominated

by the longest relaxation time. 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 technique. Second, as a step in the direction of investigating melt properties, we will extend

the simulation studies to non-dilute solutions. Finally, in order to

shed further light on the question of lattice-dependence of relaxation

behavior, we will attempt limited simulation studies of chains not

restricted to a lattice.

Characterization of UHMW Polyethylene for Synthetic Implants

H. L. Wagner and J. E. Dillon

The use of synthetic implants, man-made replacements for body

parts, is becoming more widespread every year. Currently, 130,000

implants of Ultra-High Molecular Weight Polyethylene (UHMWPE) are used

annually for a wide variety of load-bearing orthopedic prostheses such

as hip and knee joints. This is increasing not only because of our growing elderly population, but also because such surgery is being performed more frequently on younger people as the outlook for long-term

success becomes brighter.

The main objective of this project is the development of new or modified standard methods for characterizing the molecular weight and

molecular weight distribution of UHMWPE. These methods will provide

industry with a needed capability for monitoring rigorously the raw UHMWPE used in the manufacture of orthopedic implants. This capability

is necessary since the above-mentioned molecular parameters strongly

influence both the processing conditions used in the manufacture of the

implants, as well as the physical properties (wear, creep, stress

178
cracking) of the products. They will also provide a basis for issuing

an NBS reference material for the calibration of instruments used for

characterizing the molecular parameters of UHMWPE.

Zero Shear Viscosity of UHMWPE

H. L. Wagner and J. E. Dillon

Previous work has established that single point dilute solution viscosity estimates of the molecular weight of UHMWPE, the basis on which the material is currently sold, are inaccurate. This is due

primarily to the previously unrecognized shear rate dependence of the

viscosity determination, and the lack of a valid relationship between

molecular weight and viscosity (Mark-Houwink relation) for these very

high molecular weight materials. In order to provide a meaningful

characterization of UHMWPE it is first necessary to determine the

limiting viscosity number in the limit of zero shear rate. The zero

shear viscosity, an unambiguous quantity, can be the foundation of a rapid and convenient test method at finite rates of shear by polymer

producers and implant fabricators alike.

For this purpose, a low shear rotating viscometer of the ZimmCrothers type has been built. In this viscometer the shear stress is

fixed by the magnetic interaction of external electromagnets with an aluminum core set in an inner cylinder. The liquid being measured is

kept between the fixed outer cylinder and the inner rotating cylinder

suspended in the liquid. The rate of rotation is measured by a counter

timer triggered by a laser beam. The entire apparatus is suspended in an oil bath kept at a constant temperature.

In the initial experiments it was found that the precision was

inadequate for relative viscosities up to about 1.4, the generally

recommended limit for such measurements. In addition, apparent shear

rate effects were observed with samples which were known to be shear

rate independent. These difficulties turned out to be due in part to

the wobble of the rotor and were largely overcome by fabricating the

stator and rotor out of uniform bore tubing and by careful fitting of

the aluminum core, properly weighted, in the rotor.

Measurements in the modified apparatus at 34.5 °C in cyclohexane and toluene with both a 30,000 and a 12 x 10 6 molecular weight

polystyrene did not reveal any shear dependence at the low shear rates

of the rotational viscometer. The high molecular weight polymer did

show some shear rate dependence at the much higher shear rates of a

variable shear capillary viscometer in toluene and the data were a smooth continuation of the results in the rotational viscometer. Additional runs will be made on higher molecular weight anionic polystyrenes.

179
These low temperature results, although few in number were

satisfactory enough to encourage us to make measurements at 135 °C. At

this temperature, however, we find additional modifications are needed

because of dimensional changes which occur on heating.

Fractionation of UHMWPE

H. L. Wagner and J. E. Dillon

To determine the molecular weight distribution of UHMWPE, it

is necessary to fractionate the polymer because such high molecular

weight polymers cannot yet be characterized by chromatography (GPC).

Before the advent of GPC, linear polyethyl enes with weight average

molecular weights up to a few hundred thousand were frequently fractionated by column elution. However this technique becomes more difficult and less efficient as the molecular weight increases and hence

was not chosen for the fractionation of UHMWPE.

Instead, the so called "stir fractionation" technique was

used. In this method the UHMWPE whole polymer was first dissolved at

145 °C in tetralin. The temperature of the solution was then lowered

gradually with fairly rapid stirring until some polymer separated out on the stirrer. This material which separated first is the highest mo- lecular weight fraction. This was removed and the process was continued

by lowering the temperature further, removing fractions until no more

polymer precipitated.

A total of 7 fractions were obtained between 104 and 90 °C in

the first experiment. Viscosity measurements indicated a 4- fold difference in viscosity number (at the same concentration) between the

first and last fractions, indicating that at least some fractionation

has been achieved. These fractions will also be measured by light

scattering and the results should give us an idea of the fractionation

efficiency. At this point, the method looks promising.

Development of a Digital Lock-in Light Scattering Photometer

J. R. Maurey, D. B. Minor, and 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 utilizes the principle of photon counting and digital lock-in

has been tested with the measurement of previously certified SRM's.

Although, further tests are still needed, our preliminary measurements

have demonstrated an angular range of down to 8 = 15°, a dynamic range of over three decades without corrections, long term stability and reproducibility and a good dust rejection ratio.

180
Standards for Gas Transmission Rate Measurements

J. D. Barnes

The documentation of characterization measurements on the polyester

film issued as a Standard Reference Material for oxygen gas transmission

rate measurements was completed, and the result is available as NBS

Special Publication 260-58, "SRM 1470 - A Polyester Film for Oxygen Gas

Transmission Measurements. 11

We continue to assist Committees D-20 (Plastics) and F-2 (Flexible

Barrier Materials) of the ASTM in developing improved standards for

characterizing the barrier properties of plastic materials. A new

standard method presently being ballotted, for the coulometric determination of oxygen gas transmission rates references SRM 1470 as its

primary calibration standard. NBS is leading a task group formed to

revise ASTM D1434, which is the classical method for the manometric and

volumetric determination of gas transmission properties. Interlaboratory testing has demonstrated that improved standards are needed before

this method can be expected to give reliable results. ASTM task groups

working with instrumental methods for water vapor and carbon dioxide

transmission rates have received assistance in the statistical design

and analysis of interlaboratory evaluations. These efforts may well

point out needs for new or improved standards in the form of test

methods or reference materials.

A new automated permeation measuring facility is being constructed.

The new facility uses a manometric measuring technique, but it has been

designed for greater sensitivity (achieved by a cleaner vacuum on the

downstream side) and safer operation (achieved by automated safety

interlocks to guard against adverse effects from film failures during

testing) than our previous system. The new facility is designed to

operate above 100 °C, thus enabling us to study glassy polymers at

temperatures above and below the glass transition.

A laboratory minicomputer is being interfaced to the facility.

Computer control will assist in more frequent monitoring of calibration

parameters and in more detailed characterization of the operating temperature and pressure in the system. More complex sequences experiments, which are needed in studies of glass transition and annealing

phenomena, can then be carried out. Transient phenomena, including time

lags and desorption effects, are easier to study under computer control.

On-line data reduction will prove useful in detecting significant effects that occur during the course of experiments. It was necessary to

develop some software to interface the computer with an existing MIDAS

controller and to verify that vendor-provided laboratory routines could

be used in our application. Software modules for driving the completed

facility will be written as needed when construction is complete.

181
The first project to be undertaken using the new automated permeation measuring facility is a remeasurement of the oxygen gas transmission rate of SRM 1470. This project is being undertaken to ascertain

the significance of any drifts in the rates that might result from

storage.

The permeance of polymer films to gases is very sensitive to the

microstructure of the material, and gases of differing molecular diameters should be useful as probes for determining the size distribution of

free volume elements. Earlier work has shown that there are useful

correlations between molecular sizes, the state of the polymer, and

transport coefficients. We expect to explore these correlations in

experiments using several different gases and samples whose thermal and

mechanical histories have been varied so as to change the state of the

material. Data of this kind can be used to test mol ecularly-based

theories of transport in polymers. This work is also expected to provide a basis for characterizing SRM 1470 for its transmission rate with

respect to additional gases, thus allowing this SRM to be more useful in

improving the state-of-the-art in transmission measurements. These

studies may also result in improved industrial quality control techniques for characterizing barrier materials. Helium gas permeates films

much more rapidly than does oxygen or carbon dioxide. If a useful

correlation can be found between helium transmission rates and the

transmission rates of other gases, it may be possible to use helium in

rapid testing to establish whether a process is under control.

The manometric method is useful as a primary standard, but it is

inconvenient to use for industrial quality control. For this reason we expect to investigate ways of using gas chromatography in permeation

measurements. Such methods would also be useful in research where the

permeant stream contains more than one component.

There are a number of problems arising from the use of archaic

systems of units in reporting the results of molecular transport measurements. We started work on a modernized set of units, consistent

with SI, for describing such measurements. Most problems arise from a failure to recognize that the mole is the appropriate unit for characterizing the amount of substance being transported across a barrier.

Using moles per second as the starting point, it is possible to con- struct units for permeaoil ities , permeances., and matter currents that

are more meaningful than those presently being employed. This procedure

has already been followed on the certificate for SRM 1470 and in the new standard method of test for coulometric determination of oxygen gas

transmission rate.

Improved Materials for Dissolved Oxygen Measuring Devices

J. D. Barnes

During FY 1978 the Office of Ocean Engineering of the National

Oceanic and Atmospheric Administration sought technical assistance from

the NBS Polymer Science and Standards Division in improving the pre182
cision and accuracy of dissolved oxygen (DO) measuring systems using

membrane- type polarographic sensors. The request was predicated on the

idea that the polymer membranes being employed to separate the electrochemical cell from the solution to be measured were a possible source of

drifts and instabilities in the measured DO values. We could not find

support for this premise from an analysis of data presently being collected, which emphasizes the performance of the measuring system taken

as a whole.

Our studies were confined to mathematical modelling of the transient response of the sensor to step changes in DO levels or applied

voltage-. The modelling calculations of the membrane layer and the

electrolyte layer could be separated from one another. This requires

transient experiments that measure time-lags as well as permeances. The

membrane layer and the electrolyte layer are each thought of as slabs in

which the transport of oxygen to the polarographic electrode can be

treated as a diffusion problem involving a bi layered structure. The

time-lag of the composite structure is a fairly complicated function of

the time-lags of the separate layers, and the permeance of the composite

structure is simply the reciprocal of the sums of the reciprocals of the

permeances of the separate layers. It should be possible to devise a fitting algorithm that extracts the time-lags and the permeances from

transient responses, particularly if experiments can be performed using

step changes in voltage as well as step changes in DO level.

These results have implications for the characterization of inhomogeneous polymer films because they demonstrate that the diffusion coefficients and solubilities determined by sorption experiments should be

different from those obtained in permeation experiments on such films

and that the inhomogenity must be taken into account in resolving these

differences. Further modelling efforts are needed to see if these

results can be used as a characterization tool for polymer films with a “skin" whose transport properties are different from those in the "core'1 of the film.

The modelling work done for NOAA is described in N3SIR 79-1740,

"The Influence of Polymer Membrane Properties on the Performance of

Dissolved Oxygen Sensors." The results of this modelling study show

that parallel measurements of sorption-desorption kinetics and permeation kinetics on films with various microstructures may reveal interesting differences in measured values of transport coefficients. We

hope to pursue this problem.

More direct answers to the question of whether aging of polymer

membranes cause drifts in DO measuring systems should be obtainable from

measurements on membrane materials taken by themselves. A survey of

membrane materials being used in DO sensors revealed that polyethylene

has been the material of choice. This choice affords a strong electrical signal and a reasonably rapid response, but the high permeability

of polyethylene may accelerate certain electrochemical aging processes

within the electrodes. The issue of suitable materials for this application needs to be pursued more systematically by separating the

membrane component from the electrochemical components of the sensor.

183
ASTM Activities

j. D. Barnes serves as a member of the Executive Committee of ASTM

Committee F-2 (Flexible Barrier Materials) and as Chairman of Subcommittee F2.93 (Statistical Matters). This Subcommittee is responsible

for the statistical design and evaluation of interlaboratory evaluation

programs for test methods involving flexible barrier materials. Current

projects within this Subcommittee include analysis of the results of

interlaboratory test programs on bond strengths of laminates, water

vapor transmission rates, retained solvents, seal strengths for re- tortable pouches, and oxygen gas transmission of packages. A workshop

on interlaboratory testing, co-sponsored by the Statistical Subcommittee

of Committee D-20 on Plastics, will be held in February, 1980. These

efforts are aimed at improving the quality of the precision and accuracy

statements that ASTM requires in all test methods.

Dr. Barnes also serves as the Chairman of Section F 2.30.01, which

is responsible for developing test methods for measuring the barrier

properties of flexible barrier materials.

The work of Committee F-2 is closely related to that of Committee

D-20. Section D20.70.07 on Gas Transmission properties has task groups

on the coulometric method for oxygen gas transmission measurements and

on the revision of ASTM D1434, Standard Method of Test for Gas Transmission Rate of Films and Sheets. The introduction of SRM 1470 as a calibration standard has been important in assisting these task groups

in their work of improving these methods.

Dr. H. L. Wagner is Chairman of Section D20.70.05, Molecular

Weight Parameters. The Recommended Practice for the Measurement of

Number Average Molecular Weight by Membrane Osmometry has been approved

and will be published in next year's Book of ASTM Standards. The

Recommended Practice for the Determination of Weight Average Molecular

Weight by Light Scattering has been revised and will be submitted for

balloting.
CHEMICAL DURABILITY OF POLYMERS IN USE

The growing use of polymeric materials as critical parts in systems

vital to national needs such as military aircraft, nuclear reactors,

synthetic implants, and solar energy devices demands an improved understanding of the chemical factors controlling the lifetime of such parts.

Ihe total economics and safety of many large systems depend on reliable

estimates of the lifetime of component materials in actual use. Shortterm tests for predicting durability are needed for optimum materials

selection, and knowledge of polymer degradation mechanisms is needed to

guide the development of protective methods and improve materials performance. Ihis task focuses primarily on polymeric materials used in

circumstances where the usual strategy of protective additives is inadequate. F.or example, effective additives for protection against hydrolytic degradation are not in common use, yet the superior properties

of polymers with potential hydrolytic instability make these polymers

attractive to designers. Technical activities describe studies of

polyester polyurethanes used as elastomers in demanding applications.

Polymers play a major role in solar energy systems which are rapidly

growing in importance in the national energy supply. In these devices

polymers are exposed to high UV radiation levels but, in many instances,

must transmit visible radiation and therefore cannot be protected from

photolyti cal ly- induced oxidation by the usual methods of opaque coatings

or fillers. In spite of this, the economics of the systems demand that

the polymers perform satisfactorily for many years. In order to facilitate the implementation of mechanism studies of polymer oxidation, Dr.

Brian Dickens spent the period September 1978 to June 1979 as a NATO

senior scientist at Le Centre de Recherches sur les Macromolecules,

Strasbourg, Erance. The host scientist was Dr. Jean Marchal who has an international reputation based on his work on radiation-induced polymer

oxidation at room temperature.

Technical Activity

Oxidation of Polystyrene in Solution

B. Dickens and J. Marchal 1

1 CRM, Strasbourg, France

Polystyrene is much more inert to oxidation than polypropylene or polyethylene. One way of providing a measurable rate of attack is to use a solvent whose free radical derivatives are active enough to attack

the polymer. The radi olyti cal ly induced oxidation of polystyrene in

CHC 1 3 and CCI4 have already been studied to some extent at the CRM.

These investigations were extended and parallel investigations were

conducted with CH 2 CI 2 and CgH as solvents. The aims were a) to clarify the differences between the effects of chlorinated and non-chlorinated solvents; b) to study the interplay between radical transfer to

185
the solvent by hydrogen abstraction and intramolecular hydrogen abstraction on the polystyrene molecule; and c) to shed some light on the role

of RO* radicals during the oxidation (RO* radicals are formed by the

reaction of two RO2 radicals and can either abstract H or undergo 0

scission).

The analytical techniques used were gas chromatography, wet chemical analysis, and IR. The amount of ROOH groups formed on the polymer

was determined by a calorimetric method developed at CRM. The ROOH

groups were then decomposed at room temperature by Cu^/Cu* ions. According to the oxidation mechanism developed at CRM, attack on the

secondary hydrogen of PS should give benzaldehyde, whereas a repeated

attack on adjacent tertiary hydrogens should give acetophenone (both

from p-scission of alkoxyl radicals). Attack of one (isolated) tertiary

hydrogen gives a chain scission but no small molecule oxidation products

are formed. Benzaldehyde and acetophenone were produced in all solutions studied and were detected by GC measurements. The yields of

benzaldehyde and acetophenone after decomposition of the ROOH groups by

Cu^/Cu* ions were used to show that more secondary hydrogens than

tertiary hydrogens are attacked in polystyrene in chlorinated solvents.

If this is corrected for the sec tert ratio of 2:1 in polystyrene,

attack in chlorinated solvents is essentially random along the polymer

chains. Intramolecular propagation occurs and is much faster for tertiary hydrogens than for secondary hydrogens. The chain length is

governed by the concentration of R0£ radicals (i.e., the rate of initiation) and the probability of transfer to the solvent. At lower rates of

initiation more ROOH groups are produced and, in general, more ace- tophenone than benzaldehyde is formed when the ROOH groups are decomposed by Cu^/Cu* ions. It appears that in this case the kinetic chain

lengths are longer and allow more intramolecular propagation to occur.

Intramolecular propagation occurs more in CC1 4 and CH2 C1 2 than in

CHCI 3

. The H in CHC1 3 is notoriously easy to abstract. Those in CH2 C1 2 are not as active and allow longer chain lengths for the intramolecular

propagation. The production of the small molecule oxidation products

shows that the alkoxyl radicals, R0‘ , produce detrimental chain scissions even at room temperature, and their activity is not confined to

hydrogen abstraction as is sometimes believed. Protection of the polymer against oxidation may have to consider these radicals as well as the more widely recognized R0 2 (peroxyl) radicals.

Although the decomposition of ROOH by Cu ions turns out to be less

than ideal as an analytical method (because of complexations between Cu

ions and RO* radicals), the results obtained were substantiated by

integrated hydrogen absorptions in IR spectra. 13 C NMR measurements may

be a better way of measuring the site of attack on the polymer backbone.

The amount of attack on polystyrene when C 6 H 12 is used as solvent

is much smaller than in the case of chlorinated solvents. The analytical techniques used were not precise enough to give meaningful measurements on these polymers and a mechanistic comparison of the oxidations

in chlorinated and hydrocarbon solvents was not possible.

186
Chemiluminescence from Oxidizing Polymers

R. E. Florin and Brian 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 very low, estimated at

only one photon per 10 9 terminations, this inefficiency can be overcome

by the technique 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, accelerated aging methods require a long extrapolation from test

temperatures to service temperatures, over which the mechanism of

degradation can change.

The general objective is to obtain a representative data base for

correlating chemiluminescence emission rates with overall oxidation

rates for polymers of differing physical and chemical characteristics.

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 photoinitiator is added and the sample is exposed to ultraviolet light to

reach a steady-state rate of oxidation. The initiating ultraviolet

light is suddenly cut off, and the decay of chemiluminescent light

emission recorded. A simple second-order termination, such as can be

anticipated in a homogeneous rubbery or glassy polymer, should give a linear plot of inverse square root of emission rate against time, from

the slope of which the termination rate constant can be computed. To

determine the kinetic chain length and the total amount of oxidation,

the initiator consumption rate and the steady-state rate of oxygen

absorption will also be needed later. Suitable techniques are already

well known in the literature.

To conduct automated chemiluminescence experiments of the type

described here, a BASIC and a FORTRAN program have been devised. As

many as five counting-rate measurements per second can be taken and

transmitted to the computer, and the counting interval can be varied in

steps during a run. Counting rates significantly above the dark count

have been observed for several materials at temperatures of 30 to 50 °C

in trial runs. In many instances the chemiluminescence rate of the

material as first examined has been greater than in the same material

after a heating cycle. The cause of this change has not yet been determined. Termination-rate measurements on two rubbers and two glasses are

planned following this.

Further applications of the procedure are: to measure photoinitiation and termination rates, under severe conditions, of clear polymers

without additives such as might be used in solar energy equipment;

137
oxidation and chemiluminescence accompanying straining and breaking; and

inhibitor efficiency measurements. With more sophisticated mathematical

analysis, investigation of heterogeneous materials, semi -crystal! ine

polymers, blends, and filled materials, would also be possible.

Hydrolytic Degradation of Polyester Urethane Elastomers

D. W. Brown, R. E. Lowry, and L. E. Smith

In warm, humid environments the physical properties of polyester

urethane elastomers deteriorate more rapidly than expected. This has

resulted in premature failure of parts in military aircraft. Under the

sponsorship of the Office of Naval Research, we are investigating the

degradation, with the goal of developing better methods of predicting

the lifetime of these materials.

The observed deterioration has been shown to be due to the acid

catalyzed hydrolysis of the polyester component. This decreases the

molecular weight and causes changes in physical properties, which have

been the basis of lifetime estimates 1 ’ 2 ’ 3

. We found that some polyester

urethanes crystallized on aging, perturbing the effect of the decrease

in molecular weight and invalidating the lifetime predictions 4

. Consequently, our effort has been to base lifetime estimates on other

changes by correlating changes in acidity, A, with changes in the number

average molecular weight, M.

Our results for three commercial polyester urethanes show that A

and M

1 increase by equivalent amounts. Their time, t, dependence is

given by:

A = A e ktand M" 1 = m" 1 + A (e

kt

-l)

O 0 0

where subscripts denote initial values. Here k, the fractional rate of

increase in acidity, is a pseudo first order rate constant. At 100%

relative humidity k obeys the Arrhenius equation between 35 and 85 °C

and is approximately proprotional to relative humidity. The lifetime of

a polyester polyurethane should be estimated by determining k, determining A or M near the limit of use, and solving either of the above

equations for t

5

. For use under varying conditions k should be weighted

for the fraction of time spent under each condition.

The degradation of polyester urethanes can be retarded by the

addition of carbodi imides 6

. These materials function by reacting with

the acid present in the polymerl. Consequently, the equations above are

not valid if carbodi i mi de is present. We are now trying to develop a method of predicting lifetime in the presence of carbodiimide by following the disappearance of carbodiimide by infrared spectroscopy and

the concomitant changes in A and M by titration and gel chromatography

respectively.

188
References:

(1) C. S. Schollenberger and F. D. Stewart, J. Elastoplastics , 3, 28

0971).

(2) G. Magnus, R. A. Dunkovy, and F. E. Critchfield, Rubber Chem. and

Tech., 39, 1328 (1965).

(3) R. J. Athey, Rubber Age, 96, 705 (1965).

(4) D. W. Brown, R. E. Lowry, and L. E. Smith, ACS Symposium, 96, 155

(1979).

(5) D. W. Brown, R. E. Lowry, and L. E. Smith, "The Kinetics of Hydrolytic Aging of Polyester Urethane Elastomers," submitted to Macromolecules.

(6) W. Newmann, H. Holtschmidt, J. Peter, and P. Fischer, U. S. Patent

3,193,522, July 6, 1965.

Thermal, Oxidative and Hydrolytic Degradation of Polyurethanes by

Weight- loss Techniques

J. H. Flynn

This work was undertaken as part of a project whose aim was to

determine kinetic mechanisms for the thermal and hydrolytic degradation

of polyurethanes and estimate lifetime limits of polyurethane elastomers. Two methylene diphenyl diisocyanate (MDI) polyurethanes, one with

polyether, the other with polyester soft segments, have_been investigated by constant heating rate thermogravimetry from 10 1 to 10 4 deg/sec. in vacuum, nitrogen, air, water vapor, and combinations of

these atmospheres.

The degradation of the polyether polyurethane was insensitive to

the presence of oxygen or water at the high temperatures and fast

heating rates typical of commercial TG apparatus. However, at very slow

heating rates and temperatures under 200 °C, a low activation energy

oxidation reaction was found, precluding the use of high temperature

weight-loss techniques for durability prediction in this system. Although water has an effect on the weight-loss of polyester polyurethanes, the kinetics are complex and difficult to interpret. Thus, it

appears that thermogravimetric techniques are not a sufficient method of

lifetime prediction for polyurethanes, but must be used in conjunction

with other types of analysis.

1S9
Variable Heating Rate Thermoqravimetry

J. H. Flynn

The extrapolation of activation energies from accelerated conditions to service conditions for the purpose of lifetime prediction

requires extremely accurate measurements and as modest a temperature

range of extrapolation as possible. Weight-loss measurement has been a traditional means of assessing durability as electrobalances are rugged,

stable, and accurate.

The kinetics of weight loss of several polymers have been investigated in an apparatus which operates at heating rates in the range from

6 deg/mi n. to 9 deg/day. The wide range in heating rate results in a broad experimental temperature range within which one is able to ac- curately calculate parameters and test the constancy of the kinetic

process. The slow heating rate experiments reduce the reaction temperatures, thus shortening the length of extrapolation and improving the

accuracy of lifetime prediction.

Polystyrene has been investigated in air between 120 and 300 °C and

a commercial poly(methyl methacrylate) in nitrogen between 180 and

350 °C. Both of these polymers exhibit uncomplicated kinetic spectra

over the entire weight-loss and temperature ranges lending credence to

the use of weight-loss techniques for the prediction of their durability.
MIGRATION AND THE DURABILITY OF PLASTICS IN USE

All plastic items found in commerce have low molecular weight substances incorporated in them, either as a result of their method of

manufacture or from the purposeful incorporation of additives to produce

or maintain desirable properties. In use, these substances inevitably

diffuse through the polymer to some extent and may eventually migrate

out of the polymer.

The consequences of migration are two- fold. First, if the migrating

substance is a stabilizing or property enhancing additive, the plastic

is left with poorer properties or increased vulnerability to degradation

and failure. This is a major failure mode of plastics and programs concerned with polymer durability must explicitly address the possibilities

of additive migration. Second, the migrating substance becomes a contaminant of the general environment or, in the case of plastic packaging

materials, a contaminant of the material being contained and so questions are raised 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 Administration and the control of migrating substances presents an enormous challenge to the scientific basis of regulations.

The number of commercially usable polymer- addi tive combinations is

too large to be considered efficiently on a case by case basis, either

for selection of materials for 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.

The technical activities 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.

Technical Activity

Solvent Extraction Methods of Migration Measurement

S. S. Chang, W. J. Pummer, J. R. Maurey, and L. E. Smith

Following the organization of a radiotracer laboratory and a brief

exploratory study on the migration of oligomers and other additives of

plastics into solvents, a systemmatic program of measuring the migration

behavior of small molecules across the polymer/envi ronment interface was

191
undertaken this year. This program is sponsored by the Indirect Food

Additive Program of the Bureau of Foods, Food and Drug Administration,

and is aimed at developing methods for the more efficient and reasonable

regulation of packaging materials in food contact use.

The first phase of the study has been concentrated on polyolefins.

During the current year, both linear and branched polyethylene samples

were prepared from the stocks of well characterized Standard Reference

Materials 1475 and 1476. The additives studied are two 14 C-labeled

paraffinic hydrocarbons, n-C 18 H 38 and n-C 32 H66 . The radioactive tracer

technique was used in the study for its high sensitivities in being able

to detect the presence of nanogram quantities. Qualitatively, the

diffusion coefficients for smaller oligomer molecules are greater than

the larger molecules as expected from their molecular sizes. Diffusion

coefficients are also larger in the branched, less crystalline, samples.

Studies now in progress include the modification of individual samples

by thermal treatment to achieve variations in crystallinity, and the

study of ethylene-propylene copolymers to achieve varied degree of

branching as well as crystallinity. Polar antioxidants are also being

studied in low and high density polyethylene.

Different solvents were used in the migration studies, including

low molecular weight hydrocarbons, the entire composition range of

ethanol -water mixtures, food oils, and pure triglycerides. Depending

upon the nature of the solvent and the polymer, severe swelling or absorption of solvent may occur. The migration of the additive or oligomer molecules is greatly enhanced by the swelling of the polymer.

The simultaneous swelling of the polymer by the solvent and the enhancement of the movement of the migrant produce an apparent non-Fickian

behavior of the migration. In a pre-swollen polymer, e.g. , polymers

presaturatad with n-C 18 H 38 for the study of exchanging n-C 18 H 38 with the

surroundings, the diffusion is Fickian. In solvents where the solubility of the migrant is limited, equilibrium partitioning may be

reached and the final concentrations can be calculated or estimated from

the saturation solubilities. It is also possible under these conditions

to measure the uptake of the migrant by the polymer from the solvent

phase.

The studies involving food oils and triglycerides as solvents are

used to find suitable simulating solvents for food oils. It is found

that either triglycerides such as trioctanoin or even ethanol could be

considered as food oil simulating solvents for oligomer migration from

polyolefins.

Measurement of Migration in Polymers by Inverse Gas Chromatography

G. A. Senich

Inverse phase gas chromatography (IGC) provides a convenient ex- perimental approach for the determination of fundamental material constants which can be used to estimate the extent of migration of low

192
molecular weight materials from polymers into the surroundings. The

technique of I6C differs from conventional vapor phase chromatography in

that the material of interest, a polymer of negligible vapor pressure,

is employed as a stationary phase which sorbs various volatile organic

species, often referred to as probes. Processes of solution, adsorption,

and diffusion can be studied in relation to various morphological characteristics of polymers such as the degree of crystallinity both above

and below glass transition and melting temperatures. The experiment

involves injecting a pulse of the volatile solvent into a stream of

flowing carrier gas which sweeps the injected substances through a column containing the polymer of interest. At low rates of carrier gas

flow the vapor or probe reaches a steady-state distribution between the

vapor and polymer phase and the thermodynamics of polymer-solvent or polymer-migrant interaction yield an upper bound to the amount of migration expected. At high carrier gas flow rates the equilibrium state is

not approached and the kinetics of polymersol vent interactions can be

determined. The diffusion constant of the probe in the polymer can be

determined at low probe concentrations and used to estimate the extent

of migration over the time period of interest.

A laboratory to carry out IGC studies has been established over the

past year. Preliminary IGC results on NBS SRM polyethylene and alkane

systems are comparable to literature data. Further studies of the

thermodynamic interactions and diffusion behavior of a series of alkane

probes with common polyolefins are in progress. These results will be

compared with the findings of migration studies conducted by the radioactive tracer method and employed to test and refine models for migration of small molecules in polymers.

Measurement of Antioxidant Migration by Fluorimetry

F. W. Wang

The migration of antioxidants from polymers is being studied by two

types of experiments: extraction experiments and concentration profile

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. In a concentration profile experiment, a plane sheet of polymer with uniform

concentration" Of an antioxidant is immersed in a large volume of well

stirred solvent. The antioxidant concentration profile along the direction normal to the larger surfaces of the sheet is then determined at

various times by microfluorimetry , after the sheet is sectioned with a microtome to expose the profile. Comparison of results from the two

different measurement methods on the same additive-polymer system will

give information on the effects of the extracting solvent on the diffusion and the concentration dependence of the diffusion constant.

193
Three of the antioxidants which we have examined show room temperature fluorescence sufficiently intense that their migration from polymers may be conveniently studied by fluorimetry. They are N,N'-di-pnaphthyl-p-phenylenedi amine, N,N' -diphenyl-p-phenylenediamine (DPPD)

,

and 3-t-butyl-4-hydroxyanisole. We have focused our efforts on the

extraction of DPPD from low-density polyethylene. To date, we have

developed a procedure to measure the extraction of DPPD from low-density

polyethylene. This procedure involves the purification of DPPD, the

preparation of polyethylene films which have uniform thickness of about

0.02 cm, and contain DPPD uniformly distributed and undegraded by the

preparation, the construction of an extraction device equipped with a cell for making fluorescence measurements without exposing the solution

to oxygen, and the preparation of an analytical working curve relating

DPPD concentration to fluorescence intensity. This procedure will be

used to determine the migration of DPPD from low-density polyethylene to

heptane and to ethanol. Concurrently, in collaboration with Dr. R. A. Velapoldi, Center for Analytical Chemistry, we are developing the procedures to perform concentration profile experiments with the use of a

mi crofluori meter.

A Critical Compilation of Data on the Diffusion of Additives in

Polymers

J. H. Flynn

The immediate objective of this project is the compilation of a reliable data base for the prediction of the durability of polymers

containing protective additives. With support from the Office of

Standard Reference Data, a comprehensive compilation is expected to be

ready for publication by the end of FY80.

The scope of the data compilation will be limited to polyolefin

polymers. These include high and low density polyethyl enes , isotactic

and atactic polypropylenes, polyisobutylene, and poly(4-methyl pentene).

Carbon-containing migrants — organics and compounds containing organic

radicals -- will be included. Thus far, diffusion constants as a function of temperature and activation energies of diffusion have been

computed and compiled for over 200 polymer-migrant combinations. The

data compilation is being accompanied with critical annotation giving

information on the physical and chemical properties of the migrants and

polymers, experimental methods employed, models assumed for the calculation of kinetic parameters, etc.

Thus, the results will serve not only as a data source, but also as

a resource from which empirical relationships for estimating diffusion

coefficients in polyolefins may be developed and from which sufficient

information will be available to test theoretical models for diffusion

mechani sms.

194
An Empirical Formula for Diffusion Coefficients in Polyolefins

F. L. McCrackin

The diffusion coefficients of many materials in polyolefins were

fit to the formula

D = PM

F

where M depends only on the diffusing material and P and F depend only

on the polyolefin. The values of M have been tabulated for 21 materials

and values of P and F have been tabulated for 7 polyolefins. Diffusion

coefficients calculated by this equation agree in general with the

measured values within a factor of two, while the measured diffusion

coefficients cover four orders of magnitude. The diffusing materials

vary from low molecular weight gases to complex antioxidants with mo- lecular weights of several hundred.

While this formula does not predict accurate values for diffusion

coefficients, it yields useful estimates when no other means are available. It will also provide a starting point for more comprehensive

expressions which will contain parameters with some physical significance to provide a greater predictive capability.

Self Diffusion in Molten Polyethylene

D. H. Reneker, A. Peterlin, and R. Blinc

Measurements of the self diffusion coefficient of molten polyethylene made by a magnetic field gradient nuclear magnetic resonance method

were compared with recently reported measurements made by infrared analsis of the change in concentration with time near a boundary between

polyethylene and perdeutero-polyethylene. The NMR measurements yield

values for the diffusion coefficients which are several times higher

than those obtained from the concentration measurement. Further, the

values from NMR do not depend upon M^ where Mw

is molecular weight.

Analysis of the NMR method indicates that since the nuclear magnetization decays exponentially with a time constant which is approximately

proportional to 1/Mj the NMR result depends most upon the diffusion of.

material in the low molecular weight tail of the molecular weight distribution. Analysis of the behavior of a polymer with the Schulz

distribution indicates that the diffusion coefficient measured by NMR

does not depend upon the molecular weight of the sample but is a function of the breadth of the molecular weight distribution. Data from NMR

measurements on three well characterized samples with narrow molecular

weight distributions show a lower diffusion coefficient for the sample

with M = 32,000 which had the narrowest molecular weight distribution

W

and a higher diffusion coefficient for samples with = 120,000 and

13,600, both of which had a broader molecular weight distribution.

195
Extraction of Additives from Plastics

F. L. McCrackin

Physical models of the diffusion of additives in polymers are needed to provide a basis for the efficient regulation of plastics used

in food contact regulations. The rate of diffusion of an additive from

a plastic in contact with a liquid is often increased by simultaneous

diffusion of the liquid in the plastic, that is, by extraction by the

liquid. The diffusion coefficient of the additive depends on both the

concentrations of the additive and liquid in the plastic, and the diffusion coefficient of the liquid also depends on the concentrations of

both the additive and liquid. This diffusion problem can not be solved

analytically, but its solution is required for the modeling of extraction of additives from plastics by foods, as well as for the interpretation of experimental studies of solvent extraction of additives from

plastics.

A numerical finite difference method has been developed to solve

the diffusion equation for extraction, and a computer program was

written. Some initial migration curves have been obtained. The calculated migration curves will first be qualitatively compared with the

experimental extraction curves. Later, they will be fit to experimental

extraction curves and the results applied to the problem of extraction

from plastics containers in use.

Type II Diffusion in Glasses

A. Peterlin

The description of this type of diffusion was applied to spheres

and films. The analysis of the experimental observations is in perfect

agreement with the predictions of the theory which assumes a constant

velocity of the propagation of the glass-gel boundary with the gradual

formation of a steady state concentration profile in the glass in front

of the boundary. This formation yields a square root of time term in

the weight gain while the constant propagation velocity of the glass-gel

boundary yields a time proportional term which reflects the linear

increase of the swollen gel fraction with time. The geometry of the

sphere drastically modifies the time dependence of the weight gain.

Together with Professor Sarti , Naples (Italy), one has tried to explain

the propagation of the glass-gel boundary by the nucleation effect of

the crazing caused by the expansion pressure of the polymer in equilibrium with the diffusant.

Moisture Absorption and Desorption Effects in Epoxy Matrix

Composites

R. J. Rubin

The following conclusions stem from a literature survey of moisture

absorption and desorption effects in epoxy matrix composites:

196
(1) There does not appear to be a significant dependence of

durability or performance simply on diffusion coefficients of

the epoxy matrix. That is, transient effects associated with

diffusion do not appear to be generally important from the

point of view of durability although they may be important in

accelerated tests. The typical period of exposure of com- posites to a humid use environment is of sufficiently long

duration that the solubility of water in the epoxy matrix is a more dominant parameter.

(2) Absorption and desorption of water associated with ambient

variations in the relative humidity is accompanied by dimensional changes in the epoxy matrix and stresses at the epoxyfiber interface.

(3) Depending upon the nature of the reinforcing fibers, absorbed

moisture can concentrate (and attack chemically) the epoxyfiber interface.

(4) Combination of the stress variations mentioned in (2) with or without chemical attack of the interface mentioned in (3) can result in fatigue-like failure of the composite.

Theoretical methods of attacking the problem of moisture effects in

composite failure have been explored. Harlow and Phoenix 1 have made an initial attempt to apply the chain-of-bundles probability model in

studying the failure of composite materials, but these authors do not

seem to have paid attention to the possibility that the properties of

the epoxy matrix, through its absorbed water content, might play a demonstrable role in the model. The emphasis of Harlow and Phoenix lies

heavily on the statistical aspects of the problem. Additional useful

physical information appears to be available in acoustic emission studies

of fiber composite materials 2

, 3

. This information should provide additional physical inputs to any chain-of-bundles failure model of composites.

References:

(1) D. G. Hallow and S. L. Phoenix, "The Chai n-of-Bundl es Probability

Model for the Strength of Fibrous Materials I and II," J. Composite

Materials, 12, 195-214, 314-334 (1978).

(2) J. H. Williams and S. S. Lee, "Acoustic Emission Monitoring of

Fiber Composite Materials and Structures," J. of Composite Materials, 12, 348-370 (1978).

(3) A. Rotem and J. Baruch, "Determining the Load-Time History of Fiber

Composite Materials by Acoustic Emission," J. of Materials Science,

9, 1978-1798 (1974).

197
Statistical Thermodynamics of Polymer Solutions

I. C. Sanchez

The lattice fluid theory of solutions has been used to calculate

heats and volumes of mixing, lower critical solution temperatures, and

the enthalpic and entropic components of the chemical potential. Results

of these calculations have been compared with literature data on several

polyisobutylene solutions. In most instances agreement with experiment

is favorable and comparable to that obtained with the Flory equation of

state theory. Several insights into polymer solution behavior have been

obtained and include: (1) differences in equation of state properties

of the pure components make an unfavorable entropic contribution to the

chemical potential that becomes large and dominant as the gas- liquid

critical temperature of the solvent is approached; (2) limited miscibility of nonpolar polymer solutions at low and high temperatures is a manifestation of a polymer solution's small combinatorial entropy; and

(3) negative heats of mixing in nonpolar polymer solutions are caused by

the solvent's tendency to contract when polymer is added.

Theory of Interfacial Tension

C. I. Poser 1 and I. C. Sanchez

x Guest Worker

A general interfacial tension theory for n-component liquid mixtures

of arbitrary molecular weight has been formulated. The theory is based

on the lattice fluid model and the so-called "gradient approximation."

In the gradient approximation the free energy of a non-uniform fluid is

expressed as a sum of a term dependent only on the local density and a square gradient term. The theory has been applied to liquid-vapor

interfaces of organic liquids, polymer melts, binary liquid mixtures,

and polymer solutions. Currently under study are liquid-liquid interfaces in pari tally miscible liquids and polymer solutions as well as polymer-polymer interfaces.

Surprisingly accurate predictions have been obtained for pure

fluids. For non-pol ar low molecular weight liquids, the surface tension

can be calculated from the triple point to 0.7 of the gas-liquid critical

temperature with an error of less than 5% with no adjustable parameters.

The theory is somewhat less accurate for polymer melts because it tends

to overestimate the surface entropy.

For two-component systems, the lattice fluid theory requires two

mixture interaction parameters. These parameters are difficult to

determine for polymer solutions and polymer-polymer systems. As a first

approximation, we have used the geometric mean approximation to calculate surface tensions for binary systems, except in cases where sufficient data were available to refine the mixture parameters. For low198
molecular weight liquid mixtures consisting of non-polar or slightly

polar components, the geometric mean rule yields liquid- vapor interfacial tensions as a function of composition which lie within 5% of the

experimental data. The theory also correctly predicts the direction of

the deviation from ideal behavior. Comparisons of polymer solution

surface tensions (calculated using the geometric mean rule) with experiment are hindered by the scarcity of available data. The results

obtained are qualitatively correct and in good agreement with experiment

for two systems (PDMS-toluene, PIB-heptane). For liquid-liquid systems,

the geometric mean approximation must be relaxed. Preliminary studies

on such systems are encouraging. For polymer-polymer interfaces,

excellent agreement with experimental values can be obtained with

reasonable values of the mixing parameters.

Transient Phenomena in the Orientation of the Rigid Spheroids in

the Jet Flow

A. Peter! in

In the jet flow the orientation of the rigid spheroids is a onedimensional problem. Its time dependence can be expressed by a sum of

terms exponentially dependent on Dt where the A.2 D are the eigenvalues of the spacial distribution function of the symmetry axis of the

spheroids. The time dependent averages of cos

20 and cos 4 0 determine the

intrinsic optical birefringence and the light scattering of such a suspension.

199
MECHANICAL DURABILITY OF PLASTICS FOR DESIGN AND USE

Current trends are to use polymeric materials in applications where

long term performance in the use environment without adverse deterioration of mechanical properties is critically important. An example is

the increasing use of plastics and composites in automobiles to achieve

lighter weight, more fuel efficient, vehicles. The lack of adequate

test methods and data for evaluating long term mechanical performance

may result in overdesign which not only leads to more expensive items,

but also limits potential weight savings. The NBS has established joint

programs on mechanical durability with other federal agencies which are fostering the use of polymeric materials in applications with implications in areas of national concern - health, safety and energy. A joint

program with the Department of Transportation concerns the reuse of

polyethylene shipping containers for hazardous materials transportation.

The program addresses questions about long-term mechanical integrity,

especially with ladings which may be even mild stress cracking agents.

As part of the National Heart Program, the NIH supports development of

accelerated test methods for the fatigue life of biocompatible elastomers which are used as bladders in circulatory assist devices. The

Department of Energy supports development of methods to evaluate high

temperature, chemically inert, elastomers which are used as seals in

geothermal energy production. 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. 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 and environment.

The objectives of the task are to identify and analyze the principal failure mechanisms in polyethylene and elastomers under mechanical

stress in the use environment. An integral part of these objectives is

to determine relationships between microstructure, mechanical properties,

and mechanisms at the molecular level which affect mechanical durability.

To reach the objectives requires an interdisciplinary approach combining

competences in mechanical properties measurements, fracture mechanics,

continuum mechanics, chemistry and physics of molecular processes,

spectroscopic techniques of infrared, Raman and nuclear magnetic resonance, x-ray scattering, and electron and optical microscopy. This year

we have developed the capability for time resolved x-ray diffraction

which shows promise for investigating relationships between microstructure and mechanical properties.

200
Technical Activity

Spectroscopic Investigations of Failure Mechanisms in Mechanically

Deformed Polyethylene

B. M. Fanconi , J. P. Colson, and K. L. DeVries 1 University of Utah

Knowledge of the molecular mechanisms associated with deformation

and fracture in polymers 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.

The molecular mechanisms associated with mechanical deformation and

fracture in polyethylene are elucidated through comparisons between

Fourier transform infrared (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 concentration changes can be detected in difference spectra obtained

through subtraction of the digital FTIR data. The detectability of

small concentration variations is enhanced by the superior sensitivity

of the FTIR method over conventional dispersive infrared spectroscopy.

The difficulties inherent in comparing spectra of unoriented

(undrawn) and oriented polyethylene which plagued previous infrared

studies of deformed and fractured polymers have been overcome by preparing specimens for infrared analyses by casting films of the drawn and

fractured material, or of the reference polyethylene from solution or the melt. The most apparent discrepancy between our results and those

reported previously involves the direction of the change in the number

of carbonyl groups. We find that the number of carbonyl groups

decreases during fracture rather than increases as determined previously.

This result was obtained in films of fractured polyethylene which had

been prepared by melt casting as well as solution casting. On specimens

taken from regions of deformed polyethylene which did not include the

fracture surface we find that the decrease in the number of carbonyl

groups is less than when the specimens include the fracture surfaces.

We propose that the decrease in carbonyl groups in fractured polyethylene samples result from preferential backbone bond rupture occurring near carbonyl groups. Subsequent chemical reactions produce low

molecular weight ketones which are volatilized during preparation of the

films for infrared analysis. Experiments are in progress to substantiate

these results on drawn polyethyl enes to determine whether a relationship

exists between level of deformation and decrease in the number of

carbonyl groups.

201
Mechanical Durability of Polyethylene Shipping Containers

J. M. Crissman, L. J. Zapas, and G. M. Martin

This report summarizes research in the area of performance of polymeric materials used in the manufacture of large shipping containers for

hazardous materials transport, work supported by the U.S. Department of

Transportation Office of Hazardous Materials Operations. A primary goal

of this work has been the development of test methods for evaluating

stress-crack resistance of ethylene plastics and degree of crosslinking

in rotational molded polyethylene containers.

During the past year, studies concerned with stress-crack behavior

were expanded to include a variety of biaxial deformation histories such

as equi biaxial under inflation, bottle inflation, and bent strip geometries. One important result of this work is the observation that each

type of deformation examined, including earlier work on uniaxial creep,

yields essentially the same information with regard to stress-crack

behavior. On the basis of preliminary data, a new test method employing

bent strip geometry has been proposed for evaluating the stress-crack

resistance of ethylene plastics. The new test has several advantages

over the most common test in current use in that the bend geometry is

well defined and controlled and the specimen is subjected to a constant

applied load. A test of this type also has the advantage that it can be

controlled in such a manner as to optimize testing time.

Also during the past year a wholly new area of study was initiated

which is concerned with cross- 1 inkable polyethyl enes for rotational

molding. This class of materials is now entering the marketplace in the

form of large rotational ly molded containers for the transport of hazardous materials. The rotational molding of cross-linkable polyethylene

represents a different approach to container fabrication than that

employed with conventional polyethylenes. For cross-linkable polyethylenes, the physical properties of the final product are highly contingent upon the processing, in particular the cross-linking step. Properties such as impact strength, fracture toughness, and stress-crack

resistance are expected to depend rather critically upon the extent of

cross-linking. Since the degree of cross-linking clearly represents a key parameter in determining performance, test methods need to be developed which can directly correlate the two. Three types of tests are currently under investigation: stress-crack resistance, swell ratio,

and high temperature tensile modulus.

Stress-crack resistance as a function of the degree of crosslinking is currently under investigation, but the work is not yet far

enough along to report on here.

A swell ratio test based on dimensional changes alone has been

examined for a number of polyethylene samples having widely different

degrees of cross-linking and compared to the swell ratio as determined

202
by the conventional ASTM method. A high degree of linear correlation

has been established between the two methods and it has been found that

both methods yield the same information. The primary advantage of the

method based on dimensional changes is that it requires only half the

time to perform.

Measurements of the tensile modulus at high temperature carried out

on specimens of cross-linked polyethylene having widely different degrees

of cross-linking reveal that this method is rather insensitive to the

degree of cross-linking achieved and appears impractical as a test

method.

Physical Testing of Polymers for Use in Circulatory Assist Devices

R. W. Penn, G. B. McKenna, G. W. Bullman, and F. A. Khoury

This report presents results obtained during the past year in a research program on Physical Testing of Polymers for Use in Circulatory

Assist Devices carried out at the National Bureau of Standards with the

support of the National Heart, Lung, and Blood Institute of the National

Institutes of Health. The main objectives of the program are to develop

test procedures for evaluating candidate materials for use in circulatory assist devices (CAD).

The initial phase of our program had been limited by the unavailability of suitable test samples of biocompatible elastomers. To compensate for the lack of biocompatible elastomer samples, we used the standard butyl rubber for samples and we prepared and distributed this

material to other investigators engaged in the Physical Testing program.

We recently have received several square feet of "Hexsyn" biocompatible

polyolefin rubber from Dr. McMillin of Monsanto Research Corporation and

a small quantity of "Biomer" polyurethane from Dr. John Kardos of

Washington University. Also, we have received approximately thirty

square feet of "Avcothane" urethane-silicone copolymer which we have

distributed to the other investigators.

Testing of all of these materials has been initiated. We have completed preliminary stress-strain testing of all of the materials. Creep

to failure tests are proceeding in both uniaxial and biaxial loading.

Uniaxial fatigue tests using sinusoidal loading of the two carbon black

filled elastomers have shown a dependence of sample lifetime on frequency

such that they fail after the same number of stress cycles. This contradicts the notion of stress dependent additive damage. The number of

cycles to failure is independent of frequency over the frequency range

studied (from approximately 0.1 Hz. to approximately 10- 3 Hz.). It will

be of interest to check this result for the elastomers not filled with

carbon black.

Two biaxial fatigue test machines with six testing stations each

have been assembled. These devices use pressure controlled pulses of

air to inflate circular discs of the test materials at a rate of 3Hz.

203
The pulses are controlled by motor-driven reciprocating spool valves.

One of the machines is mounted in a thermostatic bath suitable for

testing at temperatures up to about 60 °C. The other is maintained at room temperature. Means have been found to prevent the evaporation of

the saline solution in which the samples are immersed and thus to permit

constant pressure amplitude testing over periods of several months.

Studies of the fracture surfaces of failed specimens are continuing.

The carbon black filled butyl and polyolefin rubbers appear to fail by a crack growth mechanism. The cracks appear to initiate in the interior

of the rubber samples, probably at carbon black aggregates. Failure of

the butyl rubber samples is detected when a small crack grows through

the sample thickness. The polyolefin rubbers fail by a much more rapidly

growing crack which extends most of the way across the specimen.

Examination of the urethane-silicone elastomer under the optical

microscope clearly reveals that the structure of these membranes is not

homogeneous. It has been established that lenticular regions (which

exhibit an essentially circular profile when viewed along the membrane

normal and which have an elliptical profile when viewed parallel to the

plane of the membrane) occur throughout the new test membranes. The

diameter of these lenticular regions varies from a few micrometers to

several dozen micrometers. The existence of the regions points to the

occurrence of phase separation on a gross scale during the casting of

the membranes. It is still not clear whether mechanical failure in

these membranes occurs preferentially at interphase boundaries.

Fundamental Aspects of the Crystallization, the Fine Structure, and

the Deformation and Orientation of Polymers

F. A. Khoury and L. H. Bolz

Activity in this broad category has been limited to two areas. Our

efforts have been primarily devoted during the past year to a study of

the habits exhibited by chain-folded polyethylene crystals grown from

dilute solutions at elevated temperatures from poor solvents (see Section 2 for summary of results). A main initial objective of this investigation was to seek appropriate solvents, from which polyethylene

crystals can be grown at temperatures which approach, and if possible

overlap, the temperature range (~ 118 °C - 130 °C) in which the polymer

can be crystallized isothermally from the molten state. There have been

numerous studies on the habits of solution grown polyethylene crystals

in the past. There is, however, relatively little knowledge on the

nature of crystals grown above ~ 100 °C. Our original premise, which

current results bear out, was that such crystals would serve as useful

models for crystal lamellae grown from the melt. The latter lamellae

are usually organized in spherulitic arrays and are consequently much

less accessible or amenable to the determination of their lateral growth

habits (lateral faceting), their conformations (hollow pyramidal, tentlike, or variously curved), and various details of the molecular organization in them (e.g. , fold staggering, tilt of chain stems relative to

fold surface). The determination of these features, and others, is

204
essential not only to an understanding of the relationships between

mechanisms of crystallization and fine structure at the molecular level,

but also to the determination of aspects of the mechanisms of polymer

deformation and orientation.

As part of an on-going study of the stress cracking characteristics

of polyethylene (Crissman and Zapas) we have recently started an investigation of the morphological changes caused in sheets of the polymer when

they are subjected to equi biaxial stresses. Information derived from

this study will also have a bearing on aspects of the mechanisms of

deformation and orientation which underlie compressive stressing as well

as biaxial orientation processes used in the manufacture of polyethylene

products (e.g. , films, containers). Some initial results are summarized:

The Habits of Polyethylene Crystals Grown from Dilute

Solutions in Poor Solvents:

Linear polyethylene fractions (M.wt. 11400-100500) and ultra

high molecular weight polyethylene (UHMWPE, M.wt. ^ 4.5 x 10 6

) have been

crystallized from 0.01% solutions in the range 95 °C - 115 °C. Heptyl

acetate, heptyl acetate/xylene mixtures, and dodecanol were among the

solvents used. Not unexpectedly all the lamellar crystals grown in that

temperature range exhibited preferential growth parallel to the b-axis,

and at the lower temperatures the lamellae exhibited {110} and (200)

lateral faceting. In addition, the axial ratio B/A* increased with

increasing crystallization temperature. Interestingly, however, we have

encountered instances in which the lateral habits of the lamellae tended

to become less well defined the higher the crystallization temperature.

In particular, crystal lamellae of the lowest molecular weight fraction

(M.wt. = 11400) grown at 115 °C from dodecanol exhibited a lenticular

lateral profile (axial ratio 5-6). Although these lamellae were bound

at opposite tips by {110} facets the long lateral edges of the crystals

were distinctly curved. Whether this later feature is associated with

the manifestation of isothermal thickening during the growth of the

crystals remains to be determined. A main feature of interest in these

crystals is that the chain stems are tilted (34°) relative to the fold

surfaces and that the sense of tilt is the same throughout each lamella

although there are indications that the magnitude of the tilt may be

smaller in the outer lateral regions of the crystals. This later

feature suggests that these crystals may possess, in the as-grown state,

a slightly S-shaped cross-section when viewed along the b-axis. Evidence that the constituent lamellae in banded polyethylene spherulites

grown from the melt possess an S-shaped cross-section has been recently

reported in the literature. Details of the stem tilt in these lamellae

are difficult to establish. Our observations on the lenticular crystals

grown from dodecanol suggest that the stems in lamellae in spherulites

may also all be tilted in the same direction relative to the surfaces of

the lamellae.

*Axial ratio B/A = length of lamella parallel to b-axis/length of lamellae

parallel to a-axis.

205
Equi biaxial Deformation of Polyethylene:

A study of the morphological changes which occur when sheets

of polyethylene are subjected to equibiaxial deformation has been

started. Replicas have been made of the surfaces of sheets which were

subjected to overall strains of up to 10%. Examination of the replicas

under the optical microscope revealed cracks in the regions of maximum

strain (polar region of bubble), which cracks were bridged by fibrils.

The lengths of the cracks varied. The most dominant crack (which

exhibited a meandering path) was 0.1 mm long and ~ 20 pm wide. Most

cracks were of the order of 50 pm long or less. In addition to these

clearly distinguishable cracks, available evidence indicates the

occurrence of preferential small scale deformation at interspherul ite

boundaries in the regions of maximum strain. These observations clearly

emphasize the lack of homogeneous biaxial deformation under equibiaxial

stressing even at strains of 10%.

Characterization of Polymeric Solids by 13C Nuclear Magnetic

Resonance

D. L. VanderHart and S. J. Kryder

NMR has traditionally been used to probe the spectral density of

molecular motions in polymers. Relaxation times have been used to infer

such information. The ability to resolve individual carbon resonances

by means of magic angle sample spinning (MASS) in polymer systems has

opened up possibilities for measuring relaxation times for each of the

carbon sites, thereby gaining information about backbone motions as opposed to si dechain motions. Such distinctions are necessary if one wishes to interpret these motions as being relevant to a macroscopic

property such as modulus.

The 13 C methods offer advantages over proton methods, particularly

in that the observed 13 C relaxation time is the superposition of the

relaxation times of individual carbons in the sample. Proton relaxation,

on the other hand, is usually the result of locally averaged relaxation

since the proton spins strongly couple to one another and do not relax

i ndi vidua! ly.

The rotating frame 13 C relaxation time, T-, , is the easiest relaxa-

’ ip C tion time to measure in polymers; furthermore, if T-j is determined by

molecular motion, it will give information about the spectral density of

motions in the mid-kilohertz range, an important range for dissipating

impact energy. Work done in our laboratory this year has led to a much

r better understanding of when T.| can be interpreted in terms of molecular motion and when it should not be interpreted this way. It has also

led to insights into ways of optimizing experimental parameters for obtaining information about molecular motion.

206
Investigation of Ultimate Resolution in Solid Polymers by

Magic Angle Sample Spinning:

Experimentally, it is found that at 15 MHz frequency for 13 C

nuclei, crystalline substances and polymers in particular, have linewidths ranging from 2-20 Hz. Furthermore, materials with less order and

more molecular motion, e.g. , glassy polymers, exhibit linewidths typically

in the range of 30-100 Hz. It is clear that the utility of the MASS

technique will often be related to one's ability to resolve resonances.

For example, if one wishes to evaluate cross-link density in a polyolefin,

and if the cross-link involves a tetrahedrally bonded carbon, then the

width of the backbone resonances which are also tetrahedral carbons is

critical since a wide, intense backbone resonance will very likely

obscure a weak resonance close by.

Furthermore, through this work and the work of others, it is becoming clear that chemical shifts observed in MASS experiments are often

sensitive to conformational differences. Thus, it was found that the

non-crystalline resonance of linear polyethylene is shifted from its

crystalline resonance because of the non-zero average gauche content of

a non-crystalline chain.

Other effects on linewidth have also been investigated such as the

effects of molecular motion and off-resonance proton. decoupl ing. The

relative importance of various linebroadening mechanisms varies from

sample to sample, especially for polymers. Only if molecular motion is an important linebroadening mechanism will resolution improve at higher

magnetic fields. Otherwise, it may even deteriorate. Even so, much

remains to be understood about resolution, and from the latest results,

it looks like the largest contribution to linewidth is chemical shift

dispersion. If this is true, it is possible that improved resolution

could be obtained by modifying sample preparation techniques. Nevertheless, it is safe to say that resolution in solids will not be as good as resolution in liquids, in fact, resolution will probably be worse by one

to two orders of magnitude. This is an important perspective to have

gained in using the 13 C MASS technique for studying polymers. For

example, this severely limits aspirations for studying tacticity in the

solid state.

Orientation and mobility of the non-crystalline regions of

linear polyethylene (LPE) and their relationship to modulus:

Non-spinning 13 C spectra of chemically simple materials like

linear polyethylene allow one to get information about orientation.

Furthermore, selection of resonances based on molecular mobility allow

one to distinguish crystalline from non-crystalline (NC) material. In

particular, the orientation in the NC region was studied as a function

of annealing in a cold drawn sample of LPE. The change in spectral

features accompanying the decrease in modulus (the latter measured by

John Crissman on similar samples) suggested that the number of tie

chains decreased with increased annealing temperature.

207
Infrared Vibrational Analysis of Conformational Disorder in

Crystalline Polyethylene

D. H. Reneker, J. Mazur, and J. P. Colson

The infrared spectrum of polyethylene in which 5% of the carbon

atoms are doubly deuterated contains bands which are attributed to

trans-trans (tt) and trans-gauche (tg) dihedral angle sequences.

Experimental observations show that even in crystalline polyethylene

there are tg sequences and that the number of sequences as measured by

the intensity of the infrared bond increases in the temperature range

between 60 and 120 °C.

The tg sequences are presumed to be in folds and other crystalline

defects such as point dislocations. Calculations of the conformations

of such defects show that the crystalline constraints result in dihedral

angles which vary over a wide range of values centered around trans and

around gauche. Calculations of the vibrational spectrum for different

fold and defect conformations show that the tt band is essentially

unaffected by the variations in the dihedral angles which adjoin the tt

pair. However, the tg band is considerably broadened since its characteristic frequency is shown to depend on the conformation of the dihedral angles which adjoin it.

The determination of an appropriate baseline for measuring the area

under the tg and tt bands is a source of considerable uncertainty. Two

choices for the baseline were examined. Both of them showed that the

tg intensity increased with temperature. One choice, a baseline fitted

to the minima and shoulders of the spectrum resulted in a baseline

position and shape that varied with temperature. The other choice

established a temperature independent baseline by extrapolating to low

temperature the parameters in the temperature dependent baselines. This

second choice resulted in a ratio of the area under the tg band which is

commensurate with the number of tg sequences expected from x-ray and

Raman measurements of the number of folds and point dislocations in the

sample.

Investigation of Disorder in Polymethylene Chains

J. Mazur and B. Fanconi

Recent work on Raman active longitudinal acoustic modes (LAM) in n- alkanes and polyethylene has demonstrated that these vibrations could be

used to determine aspects of the chain conformation of polymethylene

chains including the energy difference between gauche and trans conformations. To fully utilize vibrational analyses of LAM for this purpose

we have determined the effect of chain disorder on the frequencies and

have substantiated the validity of a previously proposed method of

calculating vibrational intensities from normal coordinate displacements.

208
We have calculated the Raman spectra of liquid n-alkanes in the LAM

frequency range. These theoretical spectra have been used to determine

the energy difference between gauche and trans rotational isomers in

polymethylenes from analysis of melt phase n-alkane spectra.

In the course of these investigations we have elucidated a previously unresolved aspect of the Raman spectra of n-alkanes by showing

that the anomalous band profiles observed in the LAM spectra of some n- alkanes result from Fermi-type resonance between LAM and transverse

acoustic modes, the latter of which have little Raman intensity in the

absence of this resonance. Our calculations have yielded both the

frequency shifts and intensity profiles resulting from these interactions. The intensity calculations were carried out using a method

previously developed for LAM intensities of disordered chains. Our

analysis provided a means of testing the intensity calculation method

and the excellent agreement found indicated that the method is reasonable.

Transport Properties of Drawn Low Density PE

R. Russo, F. de Candia, V. Vittoria 1

, and A. Peterlin

1 Naples, Italy

The drawing reduces the sorption and much more the zero concentration diffusivity, but increases the concentration dependence of the

diffusivity. Annealing reduces these effects of drawing drastically and

brings the transport properties of the sample almost back to the values

before drawing. If, however, the annealing is performed with fixed ends

the annealed material upon standing at room temperature returns, as far

as the transport properties are concerned, back to the values before the

annealing. Such an effect can be explained by slow crystallization of

the tie molecules which became partially relaxed during the annealing

but as a consequence of the fixation of the ends of the sample could not

pull back the blocks they are anchored in toward their initial position.

After crystallization they form long-range axial connectors which are

the main cause of the high axial elastic modulus. If the annealing is

performed with free ends, the sample shrinks as a consequence of the

contraction of tie molecules. After the shrinkage connects the blocks

over a much shorter distance they do not, even after partial crystallization, act as long-range connectors.

Permeation Performance of Polyethyl enes Used in Containers for

Hazardous Materials Transportation

J. C. Phillips

This project is concerned with developing test methods to be used

by the Department of Transportation in formulating regulations con- cerning the barrier properties of polyethylene shipping containers.

Efforts for the current year are concerned with determining the range of

applicability of the permachor concept of predicting permeation behavior.

209
Weight loss determinations were performed at t = 50 °C for a n-carboxylic ester series and a n-alcohol series. The ester series con- sisted of ethyl acetate, butyl acetate, and amyl acetate. The alcohol

series consisted of methyl, ethyl, propyl, butyl, hexyl, and octyl

alcohols. In addition, weight loss determinations were done for

n-heptane and n-hexadecane (cetane). Two PE bottle types were used in

these studies, p = 0.92 g/cm3 and p = 0.940 g/cm3 .

The ester and alcohol series showed a decreasing dependence of

weight loss on increasing PE density at a given time. The low density

bottle, p = 0.920 g/cm3

, showed a very large time dependence in weight

loss while in the high density bottle, p = 0.940 g/cm3

, the time dependence was comparatively much smaller.

The weight loss for the ester series decreases from ethyl acetate

to butyl acetate to amyl acetate with the first two members showing a slower decrease compared to the third member. The same relative weight

loss behavior was observed in both density bottles and the loss rate for

each member of the series appeared to be constant.

The weight loss for the alcohol series decreased from methyl to

ethyl to propyl and increased to butyl to hexyl and subsequently decreased to octyl. The loss rates seemed constant for methyl through

butyl, but appeared to show a large time dependence for hexyl and octyl.

The same general behavior for each member of the series was observed for

each density bottle, but the time dependence of the loss rate in the

high density bottle appeared to have shifted to longer times compared to

the low density bottle.

The weight loss and loss rate for the ester and alcohol series do

not show a parallel behavior to that of the n-alkanes for the range of

chain lengths investigated. The results do suggest that at large chain

lengths there may be a better correspondence. These results further

suggest that polarity and association effects for the early members of a homologous series greatly influence the relative behavior of the series

to that of the n-alkanes and, therefore, compounds any quantitative

correlations.

Optical Method of the Measurement of Transport Properties of

Strained Polymer Samples

J. Phillips, A. Peterlin, and F. Waters

An IR cell apparatus was designed and constructed for the purpose

of determining transport and mechanical properties of transparent

polymer films. The transport properties were measured from IR intensity

changes of ethyl acetate vapor at the carbonyl frequency where the

absorbence of the polymer was small or negligible. The mechanical

properties of the film were determined simultaneously by using a load

cell. The polymer, LDPE and PVF2 , were chosen to show the applicability

of the IR cell to measuring conventional and nonconventional diffusion

210
properties. The transport and mechanical properties of these polymers

were extensively investigated in ethyl acetate vapor at t = 30 °C over a wide pressure and elongation range.

The results for PE/ethyl acetate showed that sorption and desorption

were conventional and the diffusivity was approximately independent of

the concentration of the vapor. The transport properties also showed a morphological transition at about s = 0.10 for diffusivity and permeability while sorption increased continuously with strain to an apparent

limiting value. The stress relaxation at vapor pressure, p, and cyclic

sorption/desorption experiments showed an increasing difference between

stress relaxation at p = 0 which indicated that structural changes were

occurring as a function of time.

Polyvinyl idene fluoride which has a T^ -38 °C showed non-conventional or Type II behavior above a transition vapor pressure, p*, and

conventional behavior below p*. On the imposition of a uniaxial tensile

strain, transport properties and mechanical relaxation are enhanced and

the transition pressure of ethyl acetate decreases. These results indicate that Type II behavior for PVF2 /ethyl acetate at a temperature above

the glass transition temperature of the system depends on the pressure

of ethyl acetate vapor as well as the strain level of PVF2 .

The IR technique is inherently limited to polymer/vapor systems in

which the polymer has a high transparency in a region of the spectrum

where the vapor has a strong absorption peak. In order for the absorbence to be correctly translated to actual concentrations, c

v (t), corrections for changes in film thickness due to swelling and strain should

be considered and properly applied.

Non-Linear Viscoelastic Behavior of Polymeric Materials

G. B. McKenna, L. J. Zapas, and E. A. Kearsley

Project objectives are to characterize the viscoelastic behavior of

polymeric materials using non-linear viscoelastic constitutive theory.

Methods are developed to determine strain-energy functions, time dependent strain potential derivatives, and material response specific deformations such as two-step deformations and cyclic loading.

Part of this project is concerned with characterization of the

extensional creep and stress relaxation behavior of carbon black filled

rubber. We are using a modified form of the BKZ theory which accounts

for the "damage" which occurs to the elastomer upon loading and unloading of the material in order to account for the accelerated creep and

stress relaxation behavior observed in cyclic loading. This work will

bear directly on the problem of failure of filled elastomers under

fatigue loading conditions to the extent that we can describe the damage

due to cycling using a constitutive equation and to the extent that a failure envelope describes the behavior of the filled elastomer. Exper211
iments have been initiated to characterize the creep and stress relaxation behavior of the material and to obtain a failure envelope for the

material. Cyclic creep, stress relaxation and failure behavior will

also be characterized.

During the last year we substantiated a prediction made by the BKZ

theory through experiments on both poly(methyl methacrylate) (PMMA) and

a concentrated solution of poly(isobutylene) in cetane. The BKZ theory

predicts that in a two step torsional stress relaxation history where

the second step deformation, y2 > 1S half of the first step deformation,

( i . e. , y2 = h Yi ), then the second step normal stress response is

predicted to be independent of the duration of the first step and equal

to the response in a single step history at a deformation of y =

Y2

-

# Also, during last year, we determined the time dependent strain

potential derivatives, 3W/3I! and dW/dI 1 for PMMA tubes. The results of

this work indicate that aw/aii is a negative at short times and becomes

positive at high strains and long times. Such behavior is unusual and

bears directly on the concept of using a shift in the mechanical relaxation spectrum to characterize the non-linear viscoelastic behavior of

polymeric glasses. Work during the coming year will be undertaken using

solid cylinders of PMMA rather than tubes to assure that the result is

not an artifact of torsional measurements on a tube without applying an internal pressure.

Experience with various rubbery polymers has shown that the strainenergy function (from which elastic behavior can be determined) can be

measured from experiments on pure shear. Our recent work has shown that

this function can also be measured from torsion data or from combined

data from simple extension and biaxial extension. These methods are

considerably simpler than the conventional methods of measuring strainenergy. The method has been successfully applied to natural rubber

(peroxide vulcanized), high molecular weight poly( isobutylene) , and to

butyl rubber. The two parameter Martin, Roth and Stiehler equation for

characterizing a rubber has been adapted to characterize the strainenergy function in this way, also.

In the coming year, the application of these ideas to a viscoelastic

material will be examined. It is hoped that the method will lead to

simplified methods of measuring extensions! viscosity. Extensions!

viscosity is an important parameter in the technology of polymer processing and is ordinarily an extremely trying measurement.

Acoustic Emission of Crazing Polymers

A. Peterlin, R. Green, and J. Smith

Glass-bead epoxy resin composites and PMMA (commercial grade) were

strained in an Instron Tensile Tester. Water and aceton induce crazing.

Some acoustic emission was detected which was caused by the microcrack212
ing of the sample under the sharp dents of the grips. The Kaiser effect

was also observed. The frequency spectrum of the acoustic emission by

the growing crazes is probably so far below the response frequency of

the sensor that the amplitude is not sufficiently above the background

noise to be detected. Hence, only a small number of emissions could be

registered. The method would permit a destructionless testing of the

polymer specimen and of its load and deformation history if one can

perform the experiment in a less noisy environment.

Elastic Modulus and Strength of Crystalline Polymers

A. Peter! in

The basic idea of the theory of both effects starts from morphological considerations. The existence of almost fully extended chains

connecting the nearly rigid crystals through the much softer amorphous

matrix is responsible for the high elastic modulus. The presence of the

defects of the regular morphology causes the sample to fail. The situation is particularly simple in the fibrous structure when the axially

oriented microfibrils with a great many tie molecules connecting the

crystal blocks yield a high elastic modulus, up to 70 GPa in highly

drawn linear polyethylene with E = 240 GPa (elastic modulus of the

crystal in the chair direction). The defects of the microfibrillar

structure are the ends of the microfibrils where the axial connection by

taut tie molecules is drastically interrupted. Under the tensile load,

the strain in such defects is many times higher than in the bulk sample,

thus leading to microcrack nucleation and adjacent microfibril rupture.

The effect is enhanced by a high elastic modulus to the microfibril.

Consequently in a highly drawn sample the strain to break decreases with

increasing draw ratio. In spite of the increase of the modulus the

strength remains practically constant or increases much more slowly than

the axial elastic modulus. The rupture of chains detectable by ESR is an effect which occurs during the straining of the sample although it

does not determine the tensile strength.

Durability of Paper

J. C. Smith, E. E. Toth, and E. L. Graminski

The durability of paper is an important consideration in currency

applications where replacement of worn out currency is a costly operation. The Bureau of Engraving and Printing supports work at NBS to

characterize those aspects of the morphology of paper networks which

affect durability with the objectives of improving durability and to

achieve this improvement by replacing the presently used cotton and

linen pulp with a less expensive pulp made from blended wood fibers.

Before these objectives can be realized, however, it is necessary

to have an improved understanding of the relationship between the

structure of paper, the morphology of the fibers, the processing condi213
tions and the mechanical and physical properties of the paper and its

components. Over the past several years studies on the bondability of

pulp fibers at the National Bureau of Standards have helped to provide

some of this background information.

Parameters for characterizing interfiber bend strength have been

obtained from tensile tests on a low-density openweb handsheet prepared

from the pulp to be evaluated. The force-elongation curve for a specimen

from 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 is characterized by the

average elongation between bond breaks. The bond strength is characterized by an average of the force-drop magnitudes, by an average of the

energy losses resulting from bond break, or by a characteristic elongation indicative of the stretch in the network needed to cause a break.

These bonding parameters are being evaluated for handsheets of various

areal densities, made from several different pulps that were subjected

to various beating treatments. The morphologies of the handsheets and

the constituent pulp fibers are being examined by optical and scanning

electron microscopy.

Since the microstructure of the fiber network is influenced by the

manner in which water is bound to the fibers, a part of this project is

concerned with the characterization of water in pulps. Pulp fibers,

especially chemical pulp fibers, are not suitable for paper manufacture

as produced by a pulp mill. In order to make paper having suitable

properties, it is necessary to subject the fibers to mechanical action.

Mechanical action, such as beating or refining, causes fibers to imbibe

water and to become more flexible. The more flexible a fiber becomes,

the better it can conform with another fiber under pressure, which is

the hallmark of interfiber bond formation. Fiber flexibility is also a factor in the formation of other physical properties essential to the

paper conversion industry.

Part of the water imbibed by the pulp fibers is bound to the cellulose while the remaining water is considered to be free water. It is

believed that the free water is most effective for fiber flexibility.

As fibers are treated increasingly by mechanical action and imbibe more

and more water, there is a question of whether the water sequentially

imbibed is totally free water. There is the possibility that increased

mechanical action can result in a decline in crystallinity and at some

point the incremental imbibed water will be a combination of bound and

free water.

The total water imbibed by a fiber can be measured by several

methods, but the most frequently used method is by the solute exclusion

principle. Weight specimens of fiber and excess water are added to

known quantities of solutions of high molecular weight material such as dextran, with a molecular weight of 2 x 106

. The large dextran mole214
cules cannot migrate into the cellulose fibers and thus the dilution of

the dextran solution occurs by the water exterior of the fibers. The

concentration of the dextran solution is measured accurately by polarimetry. The difference between the total water in the specimen and the

amount of water which diluted the dextran is the water imbibed by the

fibers. The water imbibed by the fibers is known as the fiber saturation point.

Water, bound to cellulose, does not freeze at temperatues up to

223 K, and this has been a means for measuring bound water. A method

was developed for measuring bound water in pulps by means of differential scanning calorimetry. Weighed specimens of fiber and water were

hermetically sealed then frozen. The amount of ice in each specimen was

determined calorimetically and the total amount of water in each specimen was determined by drying the specimen to constant weight. The difference between the total water and the amount of ice in each specimen

is equal to the amount of water bound to the cellulose.

Bound water and the fiber saturation point was determined for two

beaten and unbeaten wood pulps and virgin cotton. The results indicate

that beating has no effect on the crystallinity of wood pulps, but a significant effect on the crystallinity of cotton. Additionally, most

of the imbibed water in beaten cotton pulp appears to be contained in

the shortest fiber fraction. The longest fiber fraction in beaten

cotton appears to imbibe considerably less water.

This large difference in the behavior of wood and cotton pulp

during the mechanical action process apparently results in a significant

difference in the microstructure of rag and wood pulp fiber. This difference in microstructure may be the reason for the large difference in

mechanical properties of cotton and wood pulp papers.

Configurations of Polymer Chains

R. J. Rubin

Configurations of Polymer Chains Interacting with Plane Interfaces—Treatment in Terms of a Random Flight or Diffusion

Equation:

An isolated polymer chain in solution near a surface or between

parallel surfaces will adopt various configurations depending upon the

temperature and affinity of the links for the surface. A number of

years ago, Rubin 1 and DiMarzio and Rubin2 analyzed lattice models of the

foregoing systems. In the absence of the complicating effects of interaction with surfaces, configurations of long chain molecules can be

modeled by a random flight or diffusion equation. However, it is known

from the lattice models that if the energy of attraction between links

of the polymer chain and the surface are sufficiently high then there is a discontinuous collapse of the chain on the surface at a critical

energy. The description of such discontinuous behavior within the

215
framework of a diffusion equation appears to present technical difficulties. deGennes3 and Lupine and CailU4 have proposed a method of

dealing with this problem in which the attractive (or repulsive) interactions of segments of the chain With a surface are treated in terms of

a mixed boundary condition at the surface, i.e., mP = 0 where p is

the solution of the diffusion equation. I have investigated some of the

ramifications of this approach and have calculated several quantities

which appeared to be difficult to calculate within the framework of the

lattice model:

1) the distribution function of the span of an adsorbed chain molecule

at a plane solution surface in a direction normal to the surface,

i.e., the distribution function of the thickness of the adsorbed

molecule layer.

2) the distribution of the segments of a polymer chain confined between

two parallel solution surfaces as a function of energy of interaction

and chain length.

These calculations are in the process of being outlined in a paper for

publication in the Journal of Chemical Physics.

Internal Configurations of Span Constrained Random Walks:

The spans of a random walk on a simple cubic lattice are the sides

of the smallest rectangular box with sides parallel to the coordinate

axes that entirely contains the random walk. The position of a random

walker after N steps and constrained by a set of spans S is considered.

In one dimension, if $

2 » N, the random walker tends to be located at

the extremities of the span while in the contrary case the random

walker is most likely to be found half-way between the extremities. In

higher dimensions the position of the random walker in the direction of

the largest span tends to lie at the span extremities while the position

in the direction of the smallest span tends to be in the middle.

These calculations, performed in collaboration with G. H. Weiss of

the National Institutes of Health, have been summarized in a paper which

has been accepted for publication in the Journal of Statistical Physics.

Additional calculations are planned for other properties of spanconstrained random walks including the statistics of occupancy within

the rectangular box and the expected number of points visited.

1. R. J. Rubin, J. Chem. Phys. 43, 2392 (1965).

2. E. A. DiMarzio and R. J. Rubin, J. Chem. Phys 55, 4318 (1971).

3. P. G. deGennes, Rep. Prog. Phys. 32, 187 (1969).

4. Y. Lupine and A. CailU, Can. J. Phys. 56, 403 (1978).

216
Polymeric Sealants for Geothermal Energy

E. A. Kearsley

The Department of Energy 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 Jess corrosive, chemically different, conditions.

The program in the Polymer Science and Standards Division is currently beginning a survey of the needs and uses of sealants in the geothermal industry in order to understand the actual requirements for

usage which a geothermal sealant material should meet. Concurrently, an experimental program is being designed to determine what features of the

geothermal environment dominate the lifetime of sealants. Initially,

materials will be subjected to various environments for periods of time

and then tested for mechanical properties at laboratory conditions.

Concepts such as time- temperature superposition and additivity of damage

(Bailey's criterion) will be tested for their usefulness in estimating

the performance of materials at extrapolated conditions from this laboratory data. Eventually, mechanical properties measurements at test

conditions will be made. The aim of this program is to contribute to

the development of industry- accepted screening tests for geothermal

polymer sealants.

217
TESTS, STANDARDS, AND CHARACTERIZATION FOR MANUFACTURING AND DURABILITY

OF DENTAL AND MEDICAL MATERIALS

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 collaboratively with the American Dental Association, the National

Institute of Dental Research, and the Department of Defense Medical R&D

Command. Medical materials research is guided by close interaction with

the National Heart, Lung, and Blood Institute and the ASTM F4 Committee

(Medical and Surgical Materials and Devices).

Technical Activity

Development of Adhesive Bonding Techniques

G. M. Brauer, R. L. Bowen 1

, J. M. Antonucci , D. W. Misral, J. S. Stansbury, E. E. Toth, and J. M. Cassel

Research Associate

A dentally applicable technique which established and maintained

adhesive bonding would not only offer an important means for reducing

the dental caries that is encouraged by percolation of fluids and bacteria

at restoration margins but would afford a means of changing the mode of

cavity preparation so as to reduce sound tooth structure destruction.

Strong mechanical bonding of acrylic resins to enamel surfaces can be

obtained through acid etching of such surfaces but such treatment is not

applicable to the surfaces of dentin, the other major component of

teeth. Such bonding has also not been entirely satisfactory in the

caries-preventive application of pit and fissure sealants to the occlusal

enamel surfaces of children's teeth.

A number of investigative routes to the development of adhesion to

dentin are being followed. These include: synthesis of multi-functional

methacrylate monomers that contain groups that can react with either the

organic or inorganic portion of dentin; evaluation of cyanoacrylate-based

systems; examination of urethane monomers that contain polymerizable

methacrylates and residual isocyanates; synthesis and evaluation of

multi-functional adhesion-promoting surface active amine accelerators;

218
determination of techniques by which the polymerization shrinkage and

resultant gap formation between restoration and cavity wall can be

eliminated and investigation of tooth surface cleansing techniques and

mordant treatments.

Initially, the bonding of cyanoacrylates to dentin or bone, a somewhat similar mineralized tissue, is very promising. However, the

hydrolysis as the bonded specimens are aged or thermally cycled in water

is extensive and debonding occurs rapidly. Attempts to slow down this

deleterious effect of water have not been successful. Formulations

containing various urethane-methacrylates and polymerizable diluents

have developed initial bond strengths to dentin that are less than that

attainable with cyanoacrylate and therefore are not satisfactory.

Several surface-active amines when adsorbed to a powdered hydroxyapatite

surface appear to be more reactive in the adsorbed state than when in

solution and need further examination for their adhesion promoting

ability. A number of isotonic, buffered acid solutions have been shown

to remove the adhesion-inhibiting smeared layer produced at the surface

of cut dentin and to do so without pul pal irritation. An isotonic

ferric chloride mordanting solution has been found to form a modified

dentin surface in less than 30 seconds and moderately improve adhesive

bonding to composite resins.

Dental Composite, Resin, Sealant, and Cement Chemistry and

Development

G. M. Brauer, J. M. Antonucci , J. M. Cassel , R. L. Bowen 1

, H. Argentar1

, and D. W. Misra1

Research Asociate

Early work in this laboratory resulted in a major breakthrough in

the application of dental resin systems to restorative dental practice.

Such materials constitute about one- fourth of all restorations placed

per year. Because they are more durable than the silicate cements they

replaced, considerable savings to the public is being accrued. However,

deficiencies in the currently used commercial materials include: an

ill -defined color stability problem; a high viscosity which requires

dilution with lower viscosity compatible monomers for ease of application;

insufficient storage stability except under ideal conditions;

interfacial bonding of filler to resin that is inadequate for stress

bearing applications; and a lack of capability for adhesive bonding to

the tooth surface. Current efforts are directed toward providing solutions to these areas.

The approach to developing improved color stability involves synthesis and characterization of monomer systems: which are polymerizable

at room temperature within the required time span for dental application;

which employ minimal amounts of amine accelerators — a source of color

instability; which have a more hydrophobic character as a result of

219
incorporating fluorine-containing monomers and should therefore be more

stain resistant; which may use the eutectic mixture of crystalline

methacrylate monomers as a means for eliminating color-prone impurities.

Since some discoloration may originate in reactions with residual double

bonds in the monomers, efforts are made to quantify such unsaturation.

Such analysis is fairly straightforward in the resin matrix alone but

difficult in the glass or quartz filler-reinforced composite. Infrared

and Raman spectroscopy as well as differential scanning calorimetry are

being applied to this problem. One route we are pursuing as a means of

reducing residual unsaturation is to synthesize "prepolymer" monomers,

e.g. , oligomers or polymers which have reactive functional groups capable

of generating further polymerization.

The influence of the type of viscosity- reducing methacrylate monomers diluent on the extent of marginal gap between composite restoration

and cavity wall is being explored. Water sorbing diluents as well as those that can produce extensively cross-linked systems are being examined. A correlation is being sought between gap formation (and marginal

leakage as determined with radioactive techniques) and properties of the

monomer solution (e.g., viscosity, surface tension), and of the cured

system (e.g., strength, indentation and recovery, and coefficient of

thermal expansion).

To reduce tooth pulp toxicity response to the accelerator in dental

composite restorations we are developing amine accelerators which generically should be less toxic and/or which are more efficient accelerators,

and hence are required in lower concentrations for the polymerization.

Two recently synthesized, very favorable amines for both toxicity and

accelerating efficiency are N,N-dimethylaminophenethanol and N,N-dimethylami nophenyl acetic acid. Efficiency of experimental amines is evaluated

by measuring the speed of polymerization reactions as well as the minimal

concentration of amine required to achieve polymerization at infinite

time. A semi-automatic viscosity-measuring device to determine the

state of polymerization has been designed and used in this work.

To determine specifically which components of a dental composite

system, e.g., monomer, initiator, accelerator, inhibitor, U.V. absorber,

etc. , contribute most significantly to the tooth pulp response,

collaborative projects have been initiated with the University of Florida

and the Navy Medical Research Institute in Bethesda. A first phase

result, based on pulp responses in primate teeth, did not indicate

significant irritation with any one individual ingredient. Tests are

now under way on combinations.

Wear Resistance and Mechanical Properties

G. B. McKenna, J. E. McKinney, W. Wu, and J. M. Cassel

An immediate objective of this effort is to demonstrate that data

can be obtained with an accelerated laboratory test that will predict

the durability of composite restorative materials when they are used in
stress bearing situations. Such a test procedure would eliminate the

need for very costly clinical trials that are now required. A second

principal objective is to define the mechanism of the wear process that

occurs clinically and to determine the physical test procedures and the

data that will enable a correlation to be made between the physicalmechanical properties of the composite system and its durability.

This correlation will serve to expedite development of more durable,

stress resistant composite systems.

The third version of the wear apparatus was essentially completed

during FY79. The new version determines the wear track length by counting

revolutions rather than determining the product of an assumed angular

velocity and time interval. By using “depth" measurements on flat brass

discs that are not contacted by a wear pin, we have determined that in

over 40,000 revolutions the experimental uncertainty itself will not

exceed 0.5 mm. Measurements made at ten positions around a circular

wear track in both amalgam and composites indicate there are inhomogeneous regions in specimens as we have prepared them. One factor which

appears may influence the results with amalgam is the force applied in

condensing the amalgam disc specimens. Results to date indicate we may

be able to employ synthetic durapatite pins as substitutes for those we

derived by careful and tedious grinding of human tooth enamel.

An effort has been initiated to determine the relationship, if any,

between wear resistance and the fatigue behavior of composite systems.

The approach utilizes the concept of damage accumulation that has been

elucidated’ by others working the Polymer Science and Standards Division

on mechanical properties of polymers. By cycling materials to various

fractions of their lifetime and then conducting wear measurements on the

fatigued samples, the effect of the state of damage on wear rate is

explored.

A second approach being taken to correlate the mechanical properties

of dental composites with wear behavior is the study of the resistance

of these materials to crack propagation. The study of fracture toughness

and fatigue crack propagation along with the fatigue/wear investigations

should enable us to determine the contribution of these parameters to

the wear of dental composites.

Because the BIS-GMA system commonly used in commercial dental

composites is extremely brittle, a factor which should work to reduce

their wear resistance, we have initiated efforts to develop methods for

toughening the system by incorporating elastomeric components.

221
Dental Alloy Ceramic and Implant Research

J. A. Tesk, R. P. Whitlock1

, E. E. Parry 1

, C. P. Mabie 1

, R. M. Waterstrat 1

, and D. L. Menis 1

Research Associate

Despite the difficulties encountered in handling dental gold alloy

alternatives, 25% of all porcelain veneered crowns are now constructed

of Ni-based alloys. This investigation is designed to determine the

characteristics of base metal casting alloys and associated bonding

porcelains in relation to the feasibility of their use in cast crowns

and fixed partial dentures; to determine the effects of fabrication

techniques on the clinical serviceability of the 'restorations; to explore

the overall problem of bonding dental ceramic materials to metal

substrates; and to fabricating these porcelain/metal restorations.

The goal is also to determine new or improved methods and techniques for fabrication of prostheses from dental alloys and veneering

materials; development of new alloys and veneering materials in consideration of those needs and the need for reliable sources of raw materials;

investigate new approaches for manufacture of dental porcelain and the

incorporation of fluorescing agents into porcelain; examine opportunities

for modification of operative techniques involving subperiosteal

implants through changes in materials and material properties employed

and conduct feasibility study for stress analysis-aided improvement in

implant design, and implement experimental studies for improvement of

mechanical properties and material handling characteristics of methacrylate resin based bone cement with possible applications for dental

implant, as well as orthopedic procedures.

Porcelain Fused to Base Metal Alloys

R. P. Whitlock1

, J. A. Tesk, and E. E. Parry 1

1 Research Associate

The characterization of ceramic materials available for bonding

to dental casting alloys has progressed quite well. The measurement of

dimensional change resulting from thermal cycling has been completed for

nearly all ceramic specimens. The degree of expansion/contraction of

the ceramic materials relative to the same properties in the substrate

alloys during recommended firing schedules must be compatible in order

to minimize the build-up of excessive stress in the materials which

could result in brittle fracture of the porcelain in the completed

restoration. Interfacial stress can be increased markedly through a "mismatch" of these properties. The data collected thus far indentify

considerable variation in the expansion/contraction characteristics

among different manufacturers 1 ceramic products. Further, these changes

appear to be linked directly to the thermal history of the specimen,

222
i.e. , the number of firing cycles to which the material is exposed

during fabrication processes. Generally, it would appear on early

examination of the data that the expansion coefficient (a) increases

with repeated thermal cycling. However, this phenomenon does not

manifest the same way for all materials. Further observations suggest

that qualitative and/or quantitative changes in crystallinity of the

ceramic materials may develop as a function of thermal history. Early

results from x-ray diffraction analyses indicate that, indeed, crystal

patterns are different in these specimens. Further study in this area

is under way at this time to ascertain the extent of crystalline conversion that is occurring and to correlate these differences with changes

in the refractory nature of the materials. These observations may have

major operational significance inasmuch as some ceramic materials,

apparently, can withstand more (repeated) exposure to high temperatures

during laboratory fabrication processes without showing appreciable

changes in either a or phase structure.

The ability of ceramic powders to "wet" substructure alloy

surfaces during the fusion process is a critical element in promoting

chemical and mechanical interaction at the interface which is necessary

for accomplishing optimum bonding of the materials. Analyses of particle

size distributions among the various porcelain manufacturers 1 products

have been completed and the data are being examined. Some differences

in this regard have been found to exist among the products examined.

Specific combinations of alloys and bonding porcelains have been fused

together and are presently being analyzed via void (no contact) formation

at the interface for completeness of "wetting." Variations in alloy

surface preparation, preconditioning of the substrate (oxidation) and

(opaque) porcelain application techniques are being evaluated to ascertain

the effects of these variables on the wetting process. Preliminary

analysis of the data collected in this phase of the investigation would

suggest that 1) variations in porcelain alloy combinations influence the

area of contact between the materials after fusion, and 2) different

tecnniques used for applying (opaque) porcelain powders to the alloy

substrate may alter the completeness of the "wetting" process.

Knowledge gained from the foregoing experiments should assist greatly in

more appropriate selection or matching of compatible alloy/porcelain

combinations as well as fabrication techniques.

Corrosion, Base Metal Alloys

J. A. Tesk

The extent to which pitting corrosion might be predicted in a clinical situation for a given alloy of a given composition and microstructure is of importance for at least two reasons: 1) the greater the

degree of pit formation, the more the tendency for plaque formation with

its accompanying undesired organic acid release, and 2) the pit formation

process must of itself release ions to the surrounding medium that may

be deleterious in one way or another. Availability at NBS of extensive

223
expertise and instrumentation in the area of corrosion and alloy

microstructure determination and the presence on the staff of a guest

worker from the University of Dgsseldorf for a year with a strong interest

in this area allowed an immediate attack on this phase of our base metal

alloy effort.

Three Ni-Cr alloys representing typical materials of this kind

have been investigated. These materials not only consist of different

chemical compositions but their microstructures which were observed by

light micrographs and SEM exhibit major differences. One appears to be

almost single phase with only a few precipitates within the grain

whereas the other two show a eutectic constituent in the microstructure.

Anodic polarization curves of as cast and fire-cycled samples were

generated and breakdown potentials determined in artificial saliva

solution adjusted to pH 3.2. This preliminary work points toward a lower in vitro corrosion resistance in a Be-containing alloy with a eutectic constituent in its microstructure.

New Dental Ceramic Directions

C. P. Mabie 1 and D. L. Menis 1

1 Research Associate

Porcelain frits have been developed which fuse at lower temperatures than current commercially available porcelains. These were

prepared by the calcination of gelatinous precipitates and have fusion

temperatures in the range 900 to 930 °C. Thermal expansion coefficients

of these porcelains, which determine matching of the porcelain to gold

alloy or base-metal substrates, are near those of commercial porcelains

fusing at higher temperatures.

To strengthen porcelains, quartz and alumina grains and glass

fibers are being dispersed into the gels. Attempts are being made to

fabricate micacaeous porcelains that are stronger and more machinable.

Emphasis is being placed, also, on development of porcelains with small

working-range temperatures so that interfacial stresses, which often

result in porcelain-to-metal bond failures, can be relaxed.

Investigation of new investments for the casting of base-metal

alloys continues. The objectives are to develop investments that are

less susceptible to mold reactions and in which most of the dimensional

compensation can be obtained thermally. Zirconium phosphate and aluminum

phosphate bonded investments, with flint refractory grains, are to be

studied. Investments more suitable for the especially routine titanium

alloys are being investigated.
Irradiation Effects from Neutron Activated Dental Materials

J. A. Tesk

As a result of the very limited information available in the

literature, calculations have been made to estimate the effects of

secondary radiation from gold crowns receiving neutron irradiation.

Gold is the only element examined to date and was chosen because of its

high neutron activation cross section, relatively short half life (2.7

days), and its extensive use as a dental restorative material. Estimates

on y and 0 radiation doses delivered to soft tissue were made for single

crowns and a mouth full of crowns. A 50 REM neutron exposure was

assumed as this is clearly a sublethal exposure. The results are that a single gold crown is likely to provide an additional 2 REM y dose to

local tissue and six or more adjacent crowns provide an additional dose

between 3 and 5 REM. It is estimated that the local tissue can receive

a p dose of at least 25 REM following a 50 REM neutron dose.

It has been calculated that temporary shielding of local

tissues from maximum energy 0 radiation from gold is possible by using

0.40 cm of ordinary mouth guard material. The use of higher density

materials decreases the thickness of shielding required according to the

relationship tp = 0.40, where t is the thickness and p the density.

However, for subgingival restorations, shielding is virtually impossible.

Dental Implants

J. A. Tesk

No viable dental implant exists except for what has become

known as the subperiosteal implant. This implant, while particularly

well suited for older edentulous patients who have suffered severe loss

of bone to the extent that the use of conventional dentures is ineffective, might find greater usage if the lengthy operative procedures could

be reduced. Simplification of the procedure via development of a heat

treatable, biocompatible alloy system which could be formed to fit the

bone while in the dead soft condition is being considered. The time

required to wax, invest, cast, clean, polish, and transport the implant

might be eliminated and the total time for a one-day procedure reduced

from 12-13 hours to 3-5 hours.

Much of the current interest in dental implants centers around

theoretical analysis to provide a more clear understanding of the effects

of stress on bone with anticipation that implants may be more effectively

designed by individuals armed with such knowledge. Much fundamental

information of these stress effects is not yet available. Efforts to

collaborate with the University of Illinois in developing extended

studies of stress in oral tissue using finite element techniques are being finalized.

225
Clincal and Laboratory Investigation of Dental Amalgams

N. W. Rupp 1

, G. C. Paffenbarger 1

, and R. M. Waterstrat 1

1 Research Associate

Amalgam restorations account for 70% of all restorations currently

placed. The reasons for their progressive deterioration are not as well

understood as is desired. Seven-year-old amalgam restorations are being

observed for margin integrity, tarnish, corrosion, and change in contour.

These clinical observations corroborate laboratory results which show

that amalgams having high creep values tend to "grow" or extrude out of

the cavity. This growth is not necessarily caused by repeated loading

of the tooth but, as observed earlier, the amalgam expands as a result of continuous changes in phases within the amalgam. As these

phase changes take place, forces are generated which cause expansion;

however, amalgams having low creep values are restrained in their dimensional changes by the cavity walls.

Recently it has been observed that alloys which do not contain zinc

have very little expansion even when unrestricted as compared to those

which contain zinc. This raises questions concerning the role of zinc in

these silver alloys. Specifically, does zinc facilitate phase changes?

If so, can zinc be removed from all alloys, thus reducing the phase

changes and, consequently, the forces which might result in unwanted

expansion of the amalgam restorations?

Also, we observed that the creep values of certain amalgams are increased by an increase in mercury content; other amalgams were not as sensitive to this increase in mercury content. Nonetheless, amalgams

should be mixed and inserted so that the restoration will have the

lowest possible mercury content. Even the recently-introduced alloys

that use approximately 45% mercury in the original mix should have only

39-41% remaining in the restoration.

It now appears that the elimination of the weak and corrosionprone tin-mercury phase does not always produce a more durable amalgam,

and claims for such an effect have apparently been exaggerated. Some

other factors must be partly responsible for the demonstrated clinical

superiority of the copper-containing amalgams. Resistance to creep and

corrosion are certainly desirable characteristics, but it is not clear

how these can best be achieved. Recent experiments showed that small

amounts of manganese dissolved in the conventional silver-tin alloys

produce amalgams with a sharply reduced creep and that the maximum

reduction in creep may be achieved without sacrificing essential corrosion resistance. This is accomplished by optimizing the ratio of the

copper and manganese contents so that the manganese content is minimized.

The manganese not only tends to eliminate the tin-mercury phase, but it

also seems to inhibit the formation of other phases. We are hopeful that

this will help to prevent gradual breakdown of the margins and occlusal

surfaces and prolong the useful life of the restoration.

226
Dental Enamel Chemistry and Preventive Dental Treatments

W. E. Brown 1

, L. C. Chow1

, M. Mathew1

, and G. L. Vogel 1

^Research Associate

The objective of this project is to develop and apply fundamental

information on the solubility and crystallographic structure of biologically important calcium-containing phosphate compounds to the development of improved dental caries preventive techniques. Important

portions of this effort are concerned with 1) development of 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.

Crystallographic research is utilized to provide a sound structural

basis for understanding the chemical properties of the calcium

phosphates in tooth, bone, dental calculus, and those that are formed or used in dental therapy. The chemical reactivities of calcium phosphates

are structure dependent; this program continues to be the major source

of structural information on these compounds for the National Institute

of Dental Research. Recently a new project was commenced that is capable

of providing powerful insight into the mechanism of growth of tooth and

bone crystallites. This mechanism, which involves interlayering of

enamel mineral with another calcium phosphate, was shown to be valid for

crystals grown in vitro . If this proves valid for enamel mineral in

vivo , it will be a major step forward in understanding both the roTe of

fluoride in preventing caries and the mechanism that causes enamel

mineral to incorporate impurities, e.g. , carbonate, that affect its

resistance to caries. An ultra-micro technique is being used to study

the effects of demineralizing environments on the composition of solutions within incipient carious lesions in human enamel. The objective

is to gain an increased understanding of the events that control lesion

formation. This i_n vitro study has produced, for the first time, information on pH changes within enamel and membrane potentials across the

enamel surface when the specimen is undergoing demineralizing processes.

The effectiveness of an experimental topical fluoridation procedure

has been examined in an animal study in collaboration with the National

Institute of Dental Research. The procedure consists of a pretreatment

with a calcium phosphate solution capable of forming the crystalline

compound CaHPO^HpO in the enamel. This is followed by a fluoride

treatment to cdnvert the newly-formed salt into an insoluble form of

tooth enamel. The new procedure resulted in significantly higher fluoride uptakes compared to conventional sodium fluoride or stannous fluoride

treatments. Animals that received the new treatment procedure also had

the lowest mean caries scores, but this result was not highly significant

from a statistical point of view. Further studies of the new procedure

were carried out in cooperation with the School of Dentistry, Taiwan

227
University. A single application of the commercial topical acidulated

phosphate fluoride solution (APF), preceded by a treatment with the

CaHP0 4 *2H2 0-forming solution, yielded a mean fluoride uptake of

approximately 2000 ppm when measured three months after treatment. The

mean fluoride uptake from a single APF treatment control experiment was

only 100 ppm and was not statistically significant. It appears that,

under clinical conditions, the new topical fluoridation procedure produces fluoride uptakes that are much greater than have been obtained by

fluoride agents presently in use. This procedure could prove to be a major step forward in fluoride therapy.

Phosphoric acid etchants are now in frequent use for pit and fissure

sealants, cementing of orthodontic brackets, and repair of incisal

edges. It previously had been shown that partial saturation of the

etching solution with calcium and phosphate would reduce the loss of

mineral in the initial stage of etching. It remained to be shown,

however, that the new etching procedure would produce enamel surfaces to

which plastic would adhere. Laboratory tests have now shown that the

new solutions were at least as good as the ones in use and do not cause

potentially harmful loss of enamel. The new procedure warrants clinical

eval uation.

Dental and Medical Materials Standards

J. M. Cassel , G. M. Brauer, J. A. Tesk, and N. W. Rupp 1

Research Associate

Active participation from Task Force level to the role of Subcommittee Chairman, occurs in development of dental standards through ANSI

MD 156 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 F4,

Medical and Surgical Materials and Devices, and as Chairman, USA TAG ISO

TC 150, Surgical Implants.

Molecular Weight Dependence of Polymer Adsorption on Solid Surfaces

W. H. Grant and R. E. Dehl

The adsorption of polymer molecules on solid surfaces is being

investigated for both theoretical and practical reasons. The nature of

the interaction of large molecules with surfaces is relevant to the

problem of adhesion faced in medical cardiovascular implant application,

dental plaque accumulation, and in securing plastic coatings to surfaces

in a multitude of end uses. This interaction also has an important role

in the strength and stability of polymer composite materials. It is

fundamentally important to understand the changes which occur in the

conformation of a long-chain molecule when it interacts with a surface.

The number of points of attachments at the surface and the distribution

228
of adsorbed segments, loops, and tails are all relevant to the stability

and integrity of the polymer-substrate interface.

Previous work at NBS and elsewhere has provided significant insight

into the understanding of this problem. However, recent theoretical and

experimental studies by a group from the Agricultural University in The

Netherlands is casting doubt on some of the accepted precepts about

polymer adsorption. For example, it has been commonly believed that the

adsorption of macromolecules is an irreversible process. According to

the recently developed theory, however, polymer molecules are not necessarily adsorbed irreversibly, but desorption always occurs by the displacement of short chains by longer ones in the supernatant solution.

Phenomena such as the rounded shape of the adsorption isotherm, the

dependency of the adsorbance on the solution concentration, and the ' absence of desorption upon dilution are explained in the current theory

by polydispersity of the polymer.

The predictions of the displacement theory are currently being

tested by the use of radiolabeled polystyrene fractions having narrow

molecular weight distributions. To date, studies have involved only one

radiolabeled component in a binary mixture, which has left ambiguities

in the interpretation of results. Future studies will involve the use of two different radiolabeled species, with a different nuclear tag on each species. In this way, the adsorption and displacement behavior of

the different molecular weight species will be examined in detail.

Other Division Activities

Invited Talks

"Synthesis of Polyfluorinated Polymethacrylates for Dental Applications"

IADR & AADR 57th General Session and Annual Session,

New Orleans, Louisiana

J. M. Antonucci

March 1979

"Composite Restorative Materials"

15th Annual Meeting Brazilian Dental Materials Group,

Florianopol is, Brazil

Dr. R. L. Bowen

July 1979

"Effect of Diluent on the Properties of BIS-GMA Based Composites"

IADR & AADR 57th General Session and Annual Session,

New Orleans, Louisiana

G. M. Brauer

March 1979

"New Amine Accelerators for Dental Composites"

ACS Meeting

G. M. Brauer

September 1978

229
“Two Types of Pyroelectricity in a Copolymer at Vinylidene Fluoride

& Tetrafluroethylene"

International Workshop on Electric Charges in Dielectrics,

Kyoto, Japan

M. G. Broadhurst

October 1978

"Piezoelectric Polymer Transducers"

NBS Conference Room - Science and Technology Attaches visit

M. G. Broadhurst

May 1979

"Piezoelectric Polymers"

18th Annual Meeting of the Plastics Institute of America

United English Center, New York, New York

M. G. Broadhurst

April 1979

"Piezoelectricity & Pyroelectricity in PVDF - A Model"

(CEIDP) Pocono, Pennsylvania

M. G. Broadhurst & G. T. Davis

October 1978

"Basis of Piezoelectricity in PVDF"

Univ. of Tokyo (Japan)

M. G. Broadhurst

October, 1978

"Polyvinyl idene Fluoride Viewed as a Polycrystall ine Ferroelectric

Material"

Kyoto, Japan

M. G. Broadhurst

October 1978

"Electrical Properties of Polymers"

Waseda University, Japan

M. G. Broadhurst

October 1978

"Basis of Piezoelectricity in PVDF"

Kyoto University, Japan

M. G. Broadhurst

October 1978

"Current Developments in Piezoelectric Polymer Research and Applications"

Bell Labs, Murray Hill, New Jersey

M. G. Broadhurst

August 1979

230
"Piezo- & Pyroelectricity in Polymers" Part of 1979 Summer Institute in Polymer Science and Technology, University of New York, New

Paltz, New York

M. G. Broadhurst

June 1979

"Cooperative Molecular Rotations in a Ferroelectric Polymer"

NBS Colloquim on Mathematical Modeling in Science and Engineering,

NBS

M. G. Broadhurst

August 1979

"NBS Pyroelectric and Piezoelectric Polymer R & D: I. Structure

Activity and Use"

National Bureau of Standards, Washington, D. C.

M. G. Broadhurst

January 1979

"Some Aspects of Poling PVDF"

Army Research Office Workshop on Piezoelectricity,

Dover, New Jersey

M. G. Broadhurst

January 1979

"Piezoelectric Polymers"

Video taped for future file on WDVM-TV, Steve Gendel , interviewer

M. G. Broadhurst

July 1979

"Kinetics of Hydrolytic Aging of Polyester Polyurethane Elastomers"

ACS National Meeting, Washington, D. C.

D. W. Brown

September 1979

"Mechanisms of Action of Fluoride in Prevention of Dental Caries"

ACS/Japan Chemical Congress, Honolulu, Hawaii

W. E. Brown

April 1979

"A Testing Program for Porous Polymer Tapes"

EPRI - Seminar on Solid Dielectric Materials,

Monterey, California

A. J. Bur

January 1979

"Lifetime Behavior of Polyethylene Sheets Under Inflation in the

Presence of Stress-Cracking Agent"

American Chemical Society, Washington, D. C.

J. M. Crissman

September 1979

231
"Static Fatigue of Polyethylene in Uniaxial Creep in the Presence

of Stress-Cracking Agents and Solvent"

American Chemical Society, Washington, D. C.

J. M. Crissman

September 1978

"Progress Report on Mechanical Properties Studies Relevant to the

Performance of Plastic Packaging for Hazardous Materials Transportation"

Public Meeting on Polyethylene Packagings held at the Department

of Transportation, Washington, D. C.

J. M. Crissman

July 1979

"Piezo- & Pyroelectric Polymers - Mechanisms & Application"

Gordon Research Conference, Program on Polymers,

New London, New Hampshire

G. T. Davis

July 1979

"Poling of PVDF at High Electric Fields"

CEIDP - Pocono, Pennsylvania

G. T. Davis

October 1978

"Charging of Polymer by High Electric Fields"

Conference on Electrical Insulation and Dielectric Phenomenon,

Pocono, Pennsylvania (CEIDP)

A. S. DeReggi , M. G. Broadhurst

October 1978

"Research in the Polymer Science and Standards Division"

Solar Energy Research Institute, Golden, Colorado

R. K. Eby, L. E. Smith and B. M. Fanconi

October 1978

"Order-Disorder Transitions in Polytetrafl uoroethylene"

Washington State University, Pullman, Washington

R. K. Eby

October 1978

"Order-Disorder Transitions in Polytetrafl uoroethylene"

University of Washington, Seattle, Washington

R. K. Eby

October 1978

"Order-Disorder Transitions in Polytetrafl uoroethylene"

University of Tennessee, Knoxville, Tennessee

R. K. Eby

February 1979

232
"Research in the Polymer Science and Standards Division of the

National Bureau of Standards"

Proctor and Gamble Corporate Central Research Laboratories,

Cincinnati, Ohio

R. K. Eby, M. G. Broadhurst, L. E. Smith, and B. M. Fanconi

March 1979

"Research in the Polymer Science and Standards Division of the

National Bureau of Standards"

General Motors Research Laboratory, Warren, Michigan

R. K. Eby, M. G. Broadhurst, L. E. Smith, and B. M. Fanconi

June 1979

"Research in the Polymer Science and Standards Division of the

National Bureau of Standards"

Boeing Research Laboratory, Renton, Washington

R. K. Eby, M. G. Broadhurst, L. E. Smith, and B. M. Fanconi

June 1979

"Dynamic Measurement of Nip Pressures"

10th Annual Symposium on Paper Properties & Technology,

Oxford, Ohio

S. Edelmari

May 1979

"The Adsorption of Human Serum Albumin and Gamma Globulin on Hydrophobic and Hydrophilic Surfaces"

Joint Meeting of the Japanese Chemical Society and the American

Chemical Society,

Honolulu, Hawaii

Warren Grant

April 1979

"Temperature & Molecular Weight Dependence of Polymer Dimensions in

Solution"

IBM Laboratories, San Jose, California

C. C. Han

January 1979

"Some Nonlinear Effects in Polymer Testing"

Subcommittee on Geothermal Seals of ASTM, Committee Dll. 36,

Minneapolis, Minnesota

E. A. Kearsley

June 1979

"Dental Investments"

Wilford Hall USAF Medical Center, Lock! and AFB,

San Antonio, Texas

C. P. Mabie

233
"The Crystal Structure of Pb 8 K2(P04 )6: An Apatite Without Hexed

Anions"

American Crystallographic Assoc. Meeting, Honolulu, Hawaii

Dr. Mathai Mathew

March 1979

"Measurement of Molecular Weight Distribution by Recycle Size

Exclusion Chromatography"

ACS National Meeting, Washington, D. C.

F. L. McCrackin

September 1979

"Time Dependent Failure Behavior of Glassy and Semi -Crystalline

Polymers"

IBM, San Jose Research Laboratories, San Jose, California

G. B. McKenna

January 1979

"Time Dependent Failure of PMMA and Polyethylene"

Naval Research Laboratories, Chemistry Division Seminar,

Washington, D. C.

G. B. McKenna

February 1979

"Development of Fiber Reinforced Polymer Composites for Orthopedic

Applications"

3M Corporate Research Center, St. Paul, Minnesota

G. B. McKenna

June 1979

"Time Dependent Processes in Polymeric Materials - Viscoelasticity

and Failure"

University of Minnesota, Department of Chemical Engineering,

Minneapolis, Minnesota

G. B. McKenna

June 1979

"Low Temperature Dielectric Loss Characterization of Polypropolene"

(CEIDP) Pocono, Pennsylvania

F. I. Mopsik

November 1978

"Physical Testing of Polymers for Use in Circulatory Assist

Devices"

Second Annual Contractors Meeting, Devices and Technology Branch,

NIH, Bethesda, Maryland

R. W. Penn

December 1978

234
"A Defect Which Transports a Polymer Chain Along the Molecular

Axis"

Universitat fur Makromolekulare Chemie der Albert Ludwigs

Uni vers i tat, Freiburg, West Germany

D. H. Reneker

September 1978

"A Defect Which Transports a Polymer Chain Along the Molecular

Axis"

Universitat Ulm, Ulm, West Germany

D. H. Reneker

September 1978

"Diffusion in Polymers"

Josef Stefan Institute, Ljubljana, Yugoslavia

D. H. Reneker

October 1978

"Localized Defects in Polyethylene and the Use of Infrared Absorp

tion to Measure the Number of Trans-gauche Bond Pairs"

Instituto di Chimica del Politecnio, Milano, Italy

D. H. Reneker

October 1978

"Nuclear Magnetic Resonance Line Shape, Relaxation and Self-Diffu

si on of Polyethylene in the Melt"

American Physical Society Meeting, Chicago, Illinois

D. H. Reneker

March 1979

"Overview of Technical Activities of the Polymer Science and

Standards Division of the National Bureau of Standards"

Picatinny Arsenal, Army Armament R & D Command, Dover, New Jersey

D. H. Reneker, M. G. Broadhurst, L. E. Smith, and B. M. Fanconi

May 1979

"Research in the Polymer Science and Standards Division of the

National Bureau of Standards"

Lawrence Livermore Laboratory, Livermore, California

D. H. Reneker, M. G. Broadhurst, and B. M. Fanconi

July 1979

"Transport of a Polymer Chain in a Crystal Lattice in the Axial

Direction"

IUPAC 26th International Symposium on Macromolecules, Mainz,

West Germany

D. H. Reneker

September 1979

235
"Detecting and Monitoring Deterioration in Bearings Using Piezoelectric Polymer"

Symposium on Detection Diagnosis & Prognosis System Applications,

San Antonio, Texas

S. Roth

November 1978

Discussant at Winter Gordon Conference on Polymers

Santa Barbara, California

R. J. Rubin

January 1979

"Enzyme-enzyme Interactions, Diffusion, and Steady-State Kinetics"

American Physical Society Meeting, Chicago, IL

R. J. Rubin

March 1979

"Effect of Enzyme-Enzyme Interactions on Steady-State Enzyme

Kinetics: Some Exact Results in a Lattice-Fluid Model"

International Symposium on Mathematical Topics in Biology,

Kyoto, Japan

R. J. Rubin

September 1978

"Effect of Enzyme-Enzyme Interactions on Steady-State Enzyme

Kinetics: Some Exact Results in a Lattice-Fluid Model"

Seminar, Physics Department, Waseda University, Tokyo, Japan

R. J. Rubin

September 1978

"Selection and Use of Dental Materials"

U. S. Air Force, Andrews AFB, Maryland

Dr. N. W. Rupp

May 1979

"Dental Materials - Their Selection - 1979"

College of Dentistry, Ohio State University, Columbus, Ohio

Dr. N. W. Rupp

June 1979

"Statistical Thermodynamics of Polymer & Oligomeric Mixtures"

Gordon Research Conference on Polymers, Santa Barbara, California

I. C. Sanchez

January 1979

"Statistical Thermodynamics of Polymer Solutions"

E. I. duPont de Nemours, Wilmington, Delaware

I. C. Sanchez

'May 1979

236
"Statistical Thermodynamics of Bulk and Surface Properties of

Polymer Mixtures"

Joint US/Japan Conference on Multi-component Polymers,

Kyoto University, Japan

I. C. Sanchez

December 1978

"High Resolution Solid State 13 C NMR in Polymers"

Chemistry Department Seminar, University of Maryland,

College Park, Maryland

D. L. VanderHart

November 1978

"High Resolution 13 C NMR of Solid Polymers"

Chemical Society of Washington, Topical Session, NIH,

Bethesda, Maryland

D. L. VanderHart

February 1979

"Spin-Spin and Spin-Lattice Contributions to 13 C Rotating Frame

Relaxation and Linewidths in Polymers"

Gordon Research Conference on Magnetic Resonance,

Wolfsboro, New Hampshire

D. L. VanderHart, William L. Earl, & A. N. Garroway

"Expectations for Resolution in High Resolution 13 C NMR of Solids:

Particularly Polymers"

21st Annual Rocky Mountain Conference on Analytical Chemistry,

Denver, Colorado

D. L. VanderHart

July 1979

" 13 C NMR Studies of Semi crystal! ine Polymers: Polyethylene and

Cellulose"

Sixth Annual Meeting of Analytical Chemistry and Spectroscopy

Societies, Philadelphia, Pennsylvania

D. L. VanderHart

September 1979

Publications and Patents

"Molecular Weight & Temperature Dependence of Polymer Dimensions in

Solution"

A. Ziya Akcasu and Charles C. Han

Macromolecules, 12, 276-280 (1979)

"Mechanical and Transport Properties of Drawn Low-Density Polyethylene"

L. Araimo, F. deCandia, V. Vittoria, ana A. Peterlin

J. Poly. Sci. (Phys. Edition), 16, 2087-2103 (1978)

237
“Performance of Plastic Packaging for Hazardous Materials Transportation"

J. D. Barnes, G. M. Martin, and F. L. McCrackin

Report # DOT/MTB/DHMO - 77/5

"Critical Review of Vibrational Data & Force Field Constants for

Polyethylene"

John Barnes and Bruno Fanconi

J. Physical and Chemical Reference Data, 7, 1309-1321 (1978)

"The Influence of Polymer Membrane Properties on the Performance of

Dissolved Oxygen Sensors"

John D. Barnes

NBSIR 79-1740

"SRM 1470: Polyester Film for Oxygen Gas Transmission Measurements"

John D. Barnes and Gordon M. Martin

NBS Special Publication, 260-58 (1979)

"Adhesive Bonding of Various Materials to Hard Tooth Tissues XVIII:

Synthesis of a Polyfunctional Surface-active Comonomer"

R. L. Bowen

J. Dent. Res. 58(3) : 1101-1107 (Mar. 1979)

"Adhesive Bonding of Various Materials to Hard Tooth Tissues—

Solubility of Dentinal Smear Layer in Dilute Acid Buffers"

R. L. Bowen

International Dental Journal, 28(2) : 97-107 (1978)

"Effects of Mechanical Environment on Bone Healing"

G. W. Bradley, G. B. McKenna, H. K. Dunn, A. U. Daniels, and

W. 0. Stratton

J. Bone and Joint Surgery, in press

"Durability of the Bond Between Mineralized Tissues and Potential

Adhesives"

G. M. Brauer

ACS Symposium Series, No. 95, Durability of Macromolecular

Material

s

, R. K. Eby, Editor (April 1979)

"Properties of Sealants Containing Bis-GMA and Various Diluents"

G. M. Brauer

J. Dent. Res. 57(4) : 597-607 (April 1978)

"Formation of a New Crystal Form (ap) of PVDF Under Electric Field"

D. Naegele, D. Y. Yoon, and M. G. Broadhurst

Macromolecules, 11, 1292 (1978)

238
"On the Calculation of Piezoelectricity and Pyroelectricity in

Polyvinyl i dene Fluoride"

M. G. Broadhurst, G. T. Davis, J. E. McKinney, and R. E. Collins

1978 Annual Report on CEIDP

National Academy of Science, Washington, D. C. , p. 85 (1978)

"Piezoelectricity & Pyroelectricity in Poly(vinyl idene Fluoride) - A Model"

M. G. Broadhurst, G. T. Davis, J. E. McKinney, and R. E. Collins

Journal of Applied Physics, 49, 4992 (1978)

"Piezo- & Pyroelectric Properties of Electrets"

M. G. Broadhurst and G. T. Davis

Book Chapter - Topics in Modern Physics - Electrets,

Ed. G. M. Sessler, Pub. Springer-Verlag

"Ferroelectric Polarization in Polymers"

M. G. Broadhurst and G. T. Davis

1979 Annual Report GEIDP

"Piezo- & Pyroelectric Applications of Plastics"

M. G. Broadhurst, S. Edelman, and G. T. Davis

American Chemical Society Proceedings of 176 Annual Meeting - 1979

"The Radiation- Induced Copolymerization of Tetrafluoroethylene &

Styrene at High Pressure"

Daniel W. Brown and Robert E. Lowry

J. Poly. Sci., Polymer Chemistry Edition, U, 759-768 (1979)

"Molecular Weight Standards from Sulfonation of Polystyrene"

Daniel W. Brown and Robert E. Lowry

J. Poly. Sci., Polymer Chemistry Edition, 1_7, 1039-1046 (1979)

"Crystallinity in Hydrolytically Aged Polyester Polyurethane

Elastomers"

Daniel W. Brown, Robert E. Lowry,, and Leslie E. Smith

Durability of Macromolecular Materials , p. 145-153, Chapter 10, 1979

"Interlayering of Crystalline Octacalcium Phosphate and Hydroxy 1-

apatite"

W. E. Brown, L. W. Schroeder, and J. S. Ferris

J. Phys. Chem. , 83, 1385 (1979)

Session V, General Comment: Third International Symposium on Tooth

Enamel , General Comments

W. E. Brown

J. Dent. Res. , Special Issue B (March 1979)

"Pyrolysis Gas Chromatography of Some Fluorine-Containing

Polymers"

Constantin N. Cascaval and Roland E. Florin

J. Fluorine Chemistry, 1_3, 65-70 (1979)

239
"Lifetime Behavior of Polyethylene Bars in Uniaxial Extension in

Various Chemical Environments"

J. M. Crissman

Symposium on the Durability of Macromolecular Materials, ACS Symposium Series, Vol 95, 289 (1979)

"Stress Strain-Time Diagrams, Including Failure Envelopes, for High

Density Polyethyl enes of Different Molecular Weight"

J. M. Crissman

Symposium on the Durability of Macromolecular Materials, ACS

Symposium Series, Vol. 95, 301 (1979)

"Poling of PVDF at High Electric Fields"

G. T. Davis

1978 Annual Report of Conference on Electrical Insulation & Dielectric Phenomena

National Academy of Science, Washington, D. C. , p. 75 (1978)

"Experiences in Developing an Automated Factor-Jump Method of

Thermogravimetry"

Brian Dickens

Thermochi mica Acta, 29, 87-113 (1979)

"Computer Program to Implement Automated Factor-Jump Thermogravimetry"

Brian Dickens

Thermochi mica Acta, 29, 57-85 (1979)

"Automation of Factor- Jump Thermogravimetry for Active Computer

Control"

Brian Dickens

Thermochimica Acta, 29, 41-56 (1979)

"Evaluation of Commercial and Newly- synthesized Amine Accelerators

for Dental Composites"

Dianne M. Dulik

J. Dent. Res. 58(4) , 1308-1316 (April 1979)

"Observations in Solid Polyethylene by 13 C' NMR with Magic Angle

Sample Spinning"

William L. Earl and D. L. VanderHart

Macromolecules, ]Z (1979)

Durability of Macromolecular Material

s

R. K. Eby, Editor

ACS Symposium Series 95, ACS, Washington, D. C. (1979)

"Energetics of Methyl Branches in Hydrocarbon Crystals"

B. L. Farmer and R. K. Eby

Polymer, 20, 363-366 (1979)

240
"Free Radicals in Stretched Vinylidene Chloride Copolymer"

Roland E. Florin

J. Poly. Sci., Polymer Physics Edition, J_6 , 1877 (1978)

"Application of New Kinetic Techniques to the Lifetime Prediction

of Polymers from Weight-Loss Data"

Joseph H. Flynn and Brian Dickens

Durabi 1 ity of Macromolecular Material

s

, p. 97-115, Chapter 7, 1979

"Concentration Dependence of the Diffusion Coefficient of Polystyrene at Theta-Condition"

Charles C. Han

Polymer, 20, 259-262 (1979)

"Diffusion Coefficients of the 45S and 50S States of the Large

Ribosomal Subunit of E. Col i by Quasi elastic Light Scattering"

Charles C. Han, I. N. Serdyuk, and Hyuk Yu

J. Res. of the NBS, 84, 1-8 (1979)

"Molecular Weight & Polydispersity Measurements of Polystyrene by

Quasi elastic Light Scattering"

Charles C. Han and Frank L. McCrackin

Polymer, 20, 427-432 (1979)

"Differential Scanning Calorimetry Studies of Some Analogs for the

Lipid Component of Biological Membranes"

J. T. Joseph, Albert Hybl , and Joseph H. Flynn

Chemistry and Physics of Lipids, 22, 239-243 (1978)

"Some Methods of Measurement of an Elastic Strain Energy Function

of the Valanis-Landel Type"

E. A. Kearsley

To be published in Journal of Rheology (1979)

"Some Non-Linear Effects in Polymer Testing"

E. A. Kearsley

To be published in Proceedings of ASTM Committee Dll. 36

(Geothermal Seals)

"Fabrication of Piezoelectric Polymer Film"

J. M. Kenney and S. C. Roth

NBS J. of Research (Sept. 1978)

"Aspects and Implications of the Diversity in the Habits Exhibited

by Polymer Crystals Grown from Solution"

F. Khoury and L. H. Bolz

Proceedings IUPAC 26th International Symposium on Macromolecules

(1979)

"Substitution in Barium-Fluoride Apatite: The Crystal Structures

of Ba 1 o(P0 4 ) 6F 2 , Ba6 La2N 2 (P0 4 ) 6

F 2 Ba4 Nd3Na3(P0 4 )eF2

"

M. Mathew, I. Mayer, B. Dickens, and L. W. Schroeder

J. Solid State Chem. , 28, 79-95 (1979)

241
"Crystal Structure of a Struvite Analogue, MgKP04 *6H2 0"

M. Mathew and L. W. Schroeder

Acta Cryst. , B35 , 11-13 (1979)

"Raman Intensities of Longitudinal Acoustic Modes"

J. Mazur and B. Fanconi

J. Chem. Phys. (accepted for publication)

"Monte Carlo Calculations of the Number of Ways to Pack Nonoverlapping Rods on a Square Lattice"

Frank L. McCrackin

J. Chem. Phys., 69, 5419-5423 (1978)

"The Normal Stress Response in Non-Linear Viscoelastic Materials - Some Experimental Findings"

G. B. McKenna and L. J. Zapas

Submitted to J. Rheology April 1979

"Degradation Resistance of Some Candidate Composite Biomaterials"

G. B. McKenna, G. W. Bradley, H. K. Dunn, and W. 0. Statton

J. Biomed. Matls. Res., in press

"Time Dependent Failure Behavior of Poly(methyl Methacrylate) and

Polyethylene"

G. B. McKenna and R. W. Penn

Submitted to Polymer, August 1979

"Surface Area of Dental Enamel, Bone, and Hydroxyapatite: Chemisorption from Solution"

D. N. Misra, R. L. Bowen, and G. J. Mattamal

Calcif. Tiss. Res., 26, 139-142 (1978)

"The Dielectric Loss of Polypropylene Films and Polypropylene

Laminates at Cryogenic Temperatures"

F. I. Mopsik, F. Khoury, S. J. Kryder, and L. H. Bolz

Nonmetallic Materials and Composites at Low Temperatures, p. 85-96

(Editors: A. F. Clark, R. P. Reed and G. Hartwig), Plenum Publ.

Corp. ) ( 1 979

)

"Dimensional Change of Dental Amalgam and a Suggested Correlation

Between Marginal Integrity and Creep"

G. C. Paffenbarger, N. W. Rupp, and P. R. Patel

JADA, 99, 31 (July 1979)

"The Contributions to Dental Science of Robert J. Nelsen"

Paper presented by Dr. Paffenbarger as introduction to

Dr. Robert J. Nelsen who was the recipient of the Callahan

Memorial Award of the Ohio Dental Association, Columbus, Ohio,

Sept. 23, 1978

G. C. Paffenbarger

Journal of the American College of Dentists, 46, No. 1 (Jan. 1979)

242
"Fatigue Effects in Poly(methyl methacrylate)"

R. W. Penn and G. B. McKenna

Durability of Macromolecular Materials , ed. by R. K. Eby, ACS

Symposium Series 95, ACS, Washington, D. C. (1979)

"Physical Testing of Polymers for Use in Circulatory Assist Devices"

R. W. Penn and G. B. McKenna

First Annual Report to NIH, Contract # Y01-HV-8-0003, July (1978)

"Annealing of Drawn Crystalline Polymers"

A. Peter! in

Poly. Eng. Sci., 18, 488-495 (1978)

"Contemporary Topics in Polymer Science"

A. Peterlin

Vol. 1, p. 209-231, Ed. by R. D. Ulrich, Plenum Publ. Co.,

New York, 1978

"Fracture of Fibrous Polymers"

A. Peter! i

n

Poly. Eng. & Sci., 18, 1062-1067 (1978)

"Accordion-Type LASER-Raman (ALR) Oscillations in Crystalline

Polymers"

A. Peter! i

n

j! Appl . Phys., 50, 838-844 (1979)

"Mechanical Properties of Fibrous Structures"

A. Peterlin

"Ultra-High Modulus Polymers", Ed. by A. Cifferi and I. M. Ward,

Appl. Sci. Publ., Barking, England, p. 279-320 (1979)

"Crystallization Phenomena"

A. Peterlin

"Flow Induced Crystallization", Ed. by R. L. Miller, Gordon &

Breach Sci. Publ. New York, p. 1-29 (1979)

"Elastic Modulus and Strength"

A. Peter! i

n

Poly. Eng. & Sci., 19, 118-124 (1979)

"Acoustic Emission of Polymers under Tensile Load"

A. Peterlin

"Probing Polymer Structure", Adv. Chem. Ser. 174, Ed. by J. L. Koenig,

Amer. Chem. Soc. Washington, p. 15-23, (1979)

"An Infrared Measurement of Sorption/Desorption in Polymeric

Films"

J. C. Phillips

J. of Appl. Phys., 1J_, (1978)

243
"Sorption/Desorption in Strained Polymeric Films"

J. C. Phillips, A. Peterlin and P. F. Waters

ACS Symposium Series, Vol 95 (1979)

"Surface Tension Theory of Pure Liquids and Polymer Melts"

C. I. Poser and I. C. Sanchez

J. Coll. & Int. Sci., 69, 539 (1979)

"Transport of a Polymer Chain in a Crystal Lattice in the Axial

Direction"

D. H. Reneker, B. M. Fanconi, J. Mazur, and J. P. Colson

Proceedings of the 26th International Symposium on Macromolecules,

(1979)

"Boundaries of Constrained Random Flight Polymer Chains"

R. J. Rubin and G. W. Weiss

Macromolecules, 1J_, 1046 (1978)

"Comment on Explicit Integration Method for the Time-Dependent

Schrodinger Equation"

R. J. Rubin

J. Chem. Phys., 70, 4811 (1979)

"Statistical Thermodynamics of Polymer Blends"

I. C. Sanchez

"Polymer Blends," Chap. 3, Ed. by D. R. Paul and S. Newman,

Academic Press, New York (1978)

"Statistical Thermodynamics of Polymer Solutions"

I. C. Sanchez and R. H. Lacombe

Macromolecules, U, 1145 (1978)

"Equilibrium Distribution of a Minor Constituent between a Polymer

and Its Environment"

I. C. Sanchez

Durability of Macromolecular Materials , Chap. 12, Ed. by R. K. Eby,

ACS Symposium Series 95, Washington, D. C. (1979)

"Cation Ordering in Ca2 La8 (Si 04 N 6 02

"

L. W. Schroeder and M. Mathew ; J. Solid State Chem., 26, 3.83-387 (1978)

"X02 Ion Hydration. The Crystal Structure of Mg3(P04 )2*22H20"

L. W. Schroeder, M. Mathew, and W. E. Brown

J. Phys. Chem., 82, No. 21 (1978)

"Characterizing the Interfiber Bonding of Paper Pulps: Rationale

for Bonding Parameters Derived from Tensile Test Data"

J. C. Smith

NBSIR-79- 1 722
“Characterizing the Interfiber Bonding of Paper Pulps: Tensile

Behavior of Some Mathematical Models of Paper Networks"

J. C. Smith

NBSIR 79-1735

"Models for the Migration of Paraffinic Additives in Polyethylene"

Leslie E. Smith, Isaac C. Sanchez, Shu-Sing Chang, and

Frank L. McCrackin

NBSIR 79-1598

"Models for the Migration of Additives in Polyolefins"

Leslie E. Smith, Isaac C. Sanchez, Shu-Sing Chang, Frank L. McCrackin,

and George A. Senich

NBSIR 79-1779

"Equilibrium Phase Fields in the Vanadium-Osmium System"

R. Suzy, R. Flukiger, J. L. Jorda, J. Muller, and R. M. Waterstrat

J. Less-Common Metals, 63, 45-52 (1979)

"High Power Double-Resonance Studies of Fibrous Proteins, Proteoglycans, and Model Membranes"

D. A. Torchia and D. L. VanderHart

Topics in Carbon- 13 NMR Spectroscopy , Vol. 3, George C. Levy, ed.

,

John Wiley & Sons, Inc., p. 325-360 (1979)

"Influence of Temperature and Ionic Strength on the Low-Frequency

Dielectric Dispersion of DNA Solutions"

M. S. Tung, R. J. Malinari, R. H. Cole, and J. H. Gibbs

Biopolymers, 16, 2653-2669 (1977)

" 13 C Rotating Frame Relaxation in a Solid with Strongly Coupled

Protons: Polyethylene"

D. L. VanderHart and A. N. Garroway

J. Chem. Phys. , 81_, (1979)

"The Characterization of Linear Polyethylene SRM's 1482, 1483,

and 1484"

Peter H. Verdi er and Herman L. Wagner

NBS Special Publication, 260-61 (1978)

"Monte Carlo Studies of Lattice-Model Polymer Chains: IV. Equilibrium Dimensions and Distributions in Rouse Coordinates"

Peter H. Verdi er

J. Chem. Phys., 70, 5708 (1979)

"Dynamic Flow Birefringence and Flow Dichroism of Block Copolymer

Molecules in Solution with Application to the Free-Draining Limit"

Francis W. Wang

Macromolecules, 11, 1198-1205 (1978)

245
"Internal Configurations of Span Constrained Random Walks"

G. H. Weiss and R. J. Rubin

J. Statistical Physics (accepted for pub. 1979)

Seminars for Staff and Guests

Professor C. Macosko

"Rubber Elasticity in Model Silicone Networks"

10/2/78

Professor R. Byron Pipes

"Fracture of Composite Materials"

10/5/78

Dr. J. H. Mason

"A Review of Electrical Discharges in Insulating Materials"

10/20/78

Dr. Philip Geil

"Amorphous Polyethylene"

10/24/78

Professor Guilio Sarti

"A Physical Interpretation for Case II Transport Solvent Induced

Stresses and Crazing Kinetics"

11/3/78

Yasuo Suzuoki

"Thermally Stimulated Currents in Polymers"

11/7/78

Professor Kichinoske Yahagi

"Relation Between Dielectric Breakdown and Morphological Structure

in Polyethylene"

11/8/78

James O'Reilly

"Enthalpic Retardation Times of Polymer Near the Glass Transition

Temperature"

11/16/78

Dr. D. Richter

"Study of the Segmental Diffusion of Polymers in Solution Using

Neutron Spin Echo Spectroscopy"

11/27/78

Dr. Vidomir Markovig

"Use of Radiation for Cross linking - Introduction Radiation

Technology in the Polymer Field"

12/6/78

246
Dr. W. E. Brown

"Calcium Phosphates: Gibbs, Gibbs-Duhem and Galvani"

12/ 14/78

Dr. Martin G. Broadhurst

"NBS Pyroelectric and Piezoelectric Polymer R & D: I. Structure

Activity and Use"

1 /4/79

Dr. M. G. Broadhurst

"NBS Pyroelectric and Piezoelectric Polymer R & D: II. Improper

Ferroelectricity, Space Charge Effects, and Devices"

1 / 11/79

Dr. Takeji Has hi moto

"Small Angle X-ray Scattering of Block Copolymers"

1 /31/79

Professor Georgio Ronca

"Dynamics of Swollen Rubbers: Mechanical and Optical Factors"

2/7/79

Dr. James O'Malley

"X-ray Photoelectron Spectroscopy of Polymer Surfaces"

2/ 16/79

Dr. D. L. VanderHart

"High Resolution 13C NMR in Solid Polymers: Polyethylene"

2/ 27/79

Dr. Robert Snyder

"C-H Stretching Vibrations and the Structure of Polymethylene

Chains"

3 /29/79

Professor Bernard Coleman

"On Theories of Melt Fracture of Polymers"

3/ 30/79

Kent B. Abbas

"Thermal Degradation of Polyvinylchloride"

4/ 10/79

Dr. Claude Y. P. Quivoron

"Recent Developments on the Use of Polymer Materials in Liquid

Chromatography"

4/ 25/79

Professor E. L. Thomas

"A Reassessment of Dark Field Microscopy Evidence for Order in

Amorphous Polymers"

5/ 2/79

247
Dr. Frank L. McCrackin and Herman L. Wagner

"Measurement of Molecular Weight Distribution by Recycle Size

Exclusion Chromatography"

5 /3/79

Dr. Richard Gaylord

"Who is P. G. deGennes and why is he saying those things about

polymers?"

Subtitle: "Simplified derivations of some of the deGennes scaling

formulas"

5 /8/79

Prof. Seymour Gilbert

"Physical Chemical Aspects of Migration in Polymers"

5/ 14/79

Dr. David Dollimore

"The Optimum Flocculation Conditions for Concentrated Suspensions

of Powdered Materials"

5/24/79

Dr. Alan English

"Molecular Motions Observable in Solid Polymers with Multiple

Pulse NMR"

5 /25/79

Professor Aubrey Jenkins

"Polymerization Initiated by Titanium Amides"

5/ 29/79

Dr. Mustapha Benmouna

"Temperature Effect on the Dynamic Structure Factor of Polymer

Solutions"

5/29/79

Dr. R. Koningsveld

"Thermodynamic Aspects of Polymer Compatibility"

6 /5/79

F. Michercn

"Thermodynamical Model of PVF2 and New Data"

6 / 6/79

Dr. Alan Berens

"Transport of Gases and Vapors in Rigid Polyvinylchloride"

6 / 13/79

Professor Andrew Keller

"Radiation and the Crystal Lattice of Polyethylene and N-Paraffins"

6 /25/79

248
Dr. Bernard Lotz

"Structure of Synthetic Polypeptides, Models of Transmembrane

Channel s"

7/6/79

Dr. Leonard L. Katan

"Migration in Plastics"

7/20/79

Dr. Leszek Jarecki

"Formation of Ultra-High Modulus PE by Ultra-Drawing at Elevated

Temperatures and/or Hydrostatic Pressures"

7/23/79

Prof. A. Ziya Akcasu

"Concentration and Temperature Effect on the Apparent Diffusion

Coefficient of Polymers in Solution"

8/2/79

Linda K. Nicholson

"A New Neutron Scattering Technique for Observing Polymer Solution

Dynamics"

8/8/79

Dr. M. Daoud

"An Introduction to Scaling in Polymers"

8/9/79

Dr. M. Daoud

"Vulcanization and Critical Exponents"

8/10/79

Prof. George Summerfield

"Combined X-ray and Neutron Scattering Applied to Polyethylene"

8/ 13/79

Dr. Gerhard Wegner

"Crystallization of Copolymers"

8/ 17/79

Dr. Ernest A. Boucher

"Polymer Transformation Reactions in Solution"

8/21/79

Dr. Manfred Schmidt

"Information of Polymer Branching and Polydispersity from Combined

Integrated and Dynamic Light Scattering"

8/23/79

Dr. Terence Cosgrove

"Polymer Adsorption from NMR, Neutron Scattering and Light

Scattering Measurements"

8/ 24/79

249
Professor Hiroyuki Tadokoro

"Structure and Properties of Crystalline Polymers"

9/5/79 * Professor Bruce Eichinger

"Characterization of Random Networks"

9/14/79

Technical, Professional & Standard Committee Participation & Leadership

Academy of Operative Dentistry

Dr. N. W. Rupp

President Elect and Program Chairman

AADR/IADR

Dr. W. E. Brown

Chairman, Tellers Committee

AADR/IADR

Dr. G. M. Brauer

Program Chairman, 50 Anniv. Symposium

AADR/IADR

Dr. J. M. Cassel

Washington Section Delegate

AADR/IADR

Dr. N. W. Rupp

Session Chairman

ADA Acceptance Program

Dr. J. A. Tesk

Member Porcelain Metal Alloy Subcommittee

ANSC MD 156, Dental Materials & Devices

Dr. R. L. Bowen

Member and Secretary Subcommittee - Toxicity Tests

ANSC MD 156, Dental Materials and Devices

Dr. G. M. Brauer

Member Restorative and Prosthetic Materials

ANSC MD 156, Dental Materials and Devices

Dr. N. W. Rupp

Chairman, Restorative Materials

ANSC MDSMB Medical Device Standards Management Board

Dr. J. M. Cassel

NBS Representative

250
American Physical Society

Dr. F. A. Khoury

Session Chairman

American Physical Society

Dr. D. H. Reneker

Session Chairman

APS/Division of High Polymer Physics

Dr. F. A. Khoury

Member Executi ve Commi ttee

APS/Division High Polymer Physics

Dr. G. T. Davis

Member Membership Committee

APS/Division of High Polymer Physics

Dr. I. C. Sanchez

Member Nominations Committee

ANSI 156 Base Metal Alloys

Dr. J. A. Tesk

Member

ASTM Flexible Barrier Materials F-2

Dr. J. D. Barnes

Member Executive Committee

SC. 30 Measurement Methods

SC. 93 Statistical Matters

ASTM Flexible Barrier Materials F-2

Dr. D. H. Reneker

Member

ASTM F-4 Medical and Surgical Materials and Devices

ASTM F4.20 Resources

Dr. G. M. Brauer

Chairman, Polymer Section

ASTM F4.20 Resources

ASTM F4.20.01 Polymeric Materials

Dr. G. M. Brauer

Member

ASTM F-4 Medical and Surgical Materials and Devices

ASTM F4. 20 Resources

Dr. J. M. Cassel

Member

ASTM F-4 Medical and Surgical Materials and Devices

Dr. R. K. Eby

Member, Executive Committee

251
ASTM D-2 Petroleum Products and Lubricants

Mr. L. J. Zapas

Member

ASTM D-9 Electrical Insulating Materials

Mr. W. P. Harris

Chairman D-9

SC. 90 Executive

Member SC. 12 Electrical Tests

SC. 16 Hook-up Wire Insulation

SC. 17 Thermal Capability

SC. 94 Editorial

SC. 91 International Standards

*50.96 Federal Standards

ASTM D-ll Rubber and Rubber- Like Materials

Dr. G. B. McKenna

Member

ASTM Plastics D-20

Dr. J. D. Barnes

Member SC. 12 Ethylene Plastics

SC. 19 Film and Sheeting

SC. 70 Measurement Techniques

SC. 13 Statistics

ASTM Plastics D-20

Dr. R. K. Eby

Chairman

ASTM Plastics D-20

Dr. D. H. Reneker

Member

ASTM Plastics D-20

Dr. H. L. Wagner

Member SC. 70 Analytical Methods

SC. 04 Size Exclusion Chromatography

SC. 05 Molecular Weight Parameters (Chairman)

ASTM D-27

Mr. W. P. Harris

Member

ASTM E-9 Fatigue

Dr. R. W. Penn

Member

ASTM E- 36

Mr. W. P. Harris

Member

252
ASTM Thermal Analysis E-37

Dr. J. H. Flynn

Member Executive Committee

SC. 03 Nomenclature (Chairman)

Biomaterials Society

Dr. J. A. Tesk

Session Chairperson

Experimental NMR Conference

Dr. D. L. VanderHart

Board Member

Fifth International Meeting on Ferroelectricity

Dr. M. G. Broadhurst

Member, Executive Committee

International Confederation for Thermal Analysis

Dr. J. H. Flynn

Member, Nomenclature Committee

Working Party on Symbols

ISO TC 106 Dental Materials and Devices

Dr. N. W. Rupp

Chairman, WGI Restorative Materials

ISO TC 150 Implants for Surgery

Dr. J. M. Cassel

Chairman, USA TAG

ISO TC 150 Implants for Surgery

Dr. R. K. Eby

Member

IUPAC - 1979

Dr. D. H. Reneker

Session Chairman

IUPAC - 1979

Dr. F. A. Khoury

Session Chairman

Medical Devices Technical Advisory Board

Dr. R. K. Eby

Member

NBS Advisory Panel for Tariffs on Electron Microscopes under

Florence Agreement

Dr. F. A. Khoury

253
National Research Council Panel on Experimental Techniques for the

Investigation of the Degradation of Electrical Insulation"

Dr. M. G. Broadhurst

Member, NBS Liaison

North American Thermal Analysis Society

Dr. J. H. Flynn

Member, Awards Committee

Polymer Degradation and Stability

Editorial Board

Organizing Committee of the International Workshop on Electric

Charges in Dielectrics

Dr. M. G. Broadhurst

U. S. Representative

Plastics Standards Society

Mr. G. M. Martin

Member

Plastics Standards Society

Dr. J. C. Smith

Member

Plastics Standards Society

Mr. L. J. Zapas

Member

Rheology Society of America

Mr. L. J. Zapas

Member, Executive Committee
METAL SCIENCE AND STANDARDS DIVISION

255
.
METAL SCIENCE AND STANDARDS DIVISION

R. Mehrabian, Chief

H. C. Burnett, Assistant to the Chief

D. E. Harrison, Secretary

The mission of the Division is to provide data, measurement methods,

standards and reference materials, concepts and information on the

fundamental aspects of processing, structure and physical properties of

metals to industry, government agencies and scientific organizations.

The program of the Division involves studies of the phase transformations

of metals and alloys during metallurgical processing and of the resulting

structure and properties 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 process metallurgy, phase diagrams and phase

stability, quantitative microstructural characterization including non- destructive 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 competences available in the Division are applied to research

problems in the areas of atomic, electronic, and magnetic structures;

defects, interfaces, and microstructures; phase stability and phase

transformations; and the modelling of metallurgical processes. The

program is 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 task areas: metallurgical processing; metallurgical

chemistry, structure, and property characterization; and wear and implant

alloy 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

257
among processing conditions, the internal structure of metals and their

properties and performance; so that the resulting knowledge can be used

to efficiently produce, shape, and otherwise process metals so as to

control their properties and achieve the desired reliable and durable

performance in the finished product. Results of our scientific findings

on the effect of metallurgical processing conditions on microstructure

and properties are communicated to the metallurgical community through

the organization and sponsorship of conferences and meetings on various

subjects such as acoustic emission, synthetic implant retrieval, alloy

phase formation, solidification, wear, and re-refined oils; technical

publications; active participation of Division members in various national

and international committees; lectures and personal contacts. 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. Active productive interactions

with other groups at NBS are another feature of this program 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 available competences in the Division have recently been

strengthened and expanded by: the appointment of a process metallurgist

as the new Division Chief in July, 1979, a successful budget initiative

in the area of metallic wear which will be fully implemented in FY80, 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 Metal Science and Standards Division, and the development of a transformation science budget initiative for FY81. The latter is used

below as an example of envisioned expansion of an existing competence

within the Division.

The transformation science budget initiative is aimed at improving

our national productivity in the field of metals processing. It is

composed of two interrelated programs; rapid solidification processing

and fundamental studies on the rheological behavior of partially solidified

alloys subjected to vigorous agitation, and the effect of process variables

on the microstructure and properties of cast or forged components made

from partially solid initial materials. Emphasis in this initiative

would be placed on enhancing our limited fundamental understanding of

the liquid-solid transformations involved. Mathematical and physical

process models would be developed to establish the interrelationships

between process variables such as composition, pressure, temperature,

time, etc. , and microstructures and properties. The proposed program

would be based on and expand our existing world-reknowned competence in

the field of solidification within the metallurgical processing task of

the Division. In the past year the alloy solidification program has

been expanded through a project sponsored by DARPA aimed at extending

258
current solidification theory to high liquid-solid interface velocities

encountered during rapid solidification of metal powders and filaments

and to surface modifications of conventionally processed components

subjected to directed high energy sources such as a laser or an electron

beam. There is a common underlying competence for this initiative

throughout the Division's four tasks. For example, on-line nondestructive

methods would be needed for the control of these innovative processing

techniques, the phase stability activity would address the design of

specific new alloys to exploit the benefits of rapid solidification,

while the significantly altered surface compositions and microstructures

would require fundamental studies in friction and wear. National and

international recognition of this competence within the Division is

evident by the participation of its members as chairman of the AIME

Solidification Committee, Chairman of AIME Alloy Phase Committee, Chairman

of the Second International Conference on Rapid Solidification Processing,

memberships in three NMAB committees on rapid solidification and powder

metallurgy, board membership of international journals on diffusion and

crystal growth, membership in the US-USSR subcommittee on Electro-Slag

Remelting, and membership in several ASTM committees including the

chairmanship of the ASTM Committee B-6 on Die-Cast Metals and Alloys,

and the Chairmanship of the ASTM Committee E-42 on Surface Analysis.

259
METALLURGICAL PROCESSING FOR ALLOY DURABILITY

The properties of alloys depend on their compositions and microstructures, which in turn depend on their processing history. Thus, the

durability and performance of alloy components depend strongly on the

solidification processes, transformations, diffusion and other kinetic

changes which the alloys undergo during preparation and use. The

objective of the present task is to develop data and understanding

concerning the transformations and kinetic processes in alloys which

influence final alloy compositions and microstructures. With new types

of advanced materials, such as metallic glasses, and with the rising

importance of materials with controlled compositions, such as achieved

in protective alloy diffusion coatings, the understanding of the mechanisms governing these processes is increasingly important.

During the past year, a new program on kinetic effects arising

during rapid alloy solidification was initiated. Rapid solidification

can be used to produce alloy powders which show unusual homogeneity and

also can yield amorphous alloy structures, i.e., metallic glasses. In

this task, basic aspects of metallic glass formation, the effect of

solidification velocity on the stable and unstable phases formed, and

conditions for maintaining interface stability in order to promote alloy

homogeneity are being investigated. Applications of rapid solidification technology include formation of new types of alloys with special

properties unattainable by conventional means, unique surface modification techniques and improvements in powder metallurgy products. A

budget initiative in this area was successfully developed for.FY 81.

Task members are organizing an international conference on rapid

solidification processing to be held in March 1980.

In other significant accomplishments, the onset of convection

caused by simultaneous concentration and temperature gradients during

directional solidification of alloys was analyzed and predicted. Since

interface velocities and surface tension effects are important in many

solidification and transformation processes, work to improve methods of

measuring these has been undertaken. Techniques are being developed to

provide Auger measurements of surface impurities and highly accurate

surface tension measurements simultaneously on the same metal sample.

Division members serve as chairman of the AIME Solidification Committee,

on the boards of international journals on diffusion and crystal growth

and on several ASTM and NMAB committees on alloy processing, including

the chairmanship of ASTM Committee B-6 on Die-Cast Metals and Alloys.

Initial steps have been taken to automate our diffusion data files.

Analyses are being made of diffusion data in brasses and bronzes to

complete a review on mass transport in copper systems. The initial

volume in this series, which was published last year in cooperation with

the International Copper Research Association, has already sold out its

first printing. Kinetic calculations were made of the effect of vacancy

binding on the diffusion of non-equilibrium vacancies. Significant

effects on alloy segregation and on swelling caused by void growth in

irradiated nuclear-reactor alloys were found.

260
The technical activities described in this task are rapid solidification, alloy solidification, interface velocity measurements, surface

tension measurements, diffusion in metals data and diffusion kinetics.

Technical Activity

Rapid Solidification

W. J. Boettinger, S. R. Coriell, and J. W. Cahn

In the past twenty years many processes have been invented which

subject liquid alloys to cooling rates ranging up to TO 10 K/s. Exciting

new materials as well as improved traditional material have been produced

in the form of powders, ribbons, filaments, and 'surface layers. Examples

of new materials are metallic glasses and new metastable phases. Improved traditional materials have been solidified with the absence of

unwanted phases and reduced or completely eliminated microsegregation.

A broad class of experimental results on rapidly solidified materials is

extremely difficult to understand based on a simple application of

existing theory. It is, therefore, important to extend current solidification theory to high velocities.

This project, begun in April 1979, has initially focused on three

topics: a) microsegregation as influenced by the shape stability of the

freezing interface, b) metastable reaction sequences in multicomponent

systems, and c) glass formation by rapid cooling of eutectic alloys.

Brief summaries of progress in these areas are reported below.

(a) Microsegregation and Stability at the Solidification

Interface

During freezing of alloys instabilities can occur in which a smooth solidification front (separating solid from liquid) becomes wavy

and eventually breaks down into a broad dendritic zone of coexisting

solid and liquid. As a result of the breakdown, the various chemical

components segregate between solid and liquid and when the alloys are

finally solid the segregation pattern is frozen in. For conventional

solidification the smooth solidification front can be maintained by

solidifying slowly, maintaining a high temperature gradient. Under

extremely rapid solidification another region of stability has been

predicted which is independent of temperature gradient. Calculations of

the stability-instability demarcation have been carried out for Al-Cu

alloys. For large velocities, the absolute stability criterion of

Mullins and Sekerka is a good approximation to c*, viz.

c* = k

2 T

M

rV/[(k-l)mD] = 1.9 (10

_3

)V

for Al-Cu alloys, where T

M

is the melting point and T is the ratio of

the solid-liquid surface tension and latent heat of fusion per unit

volume. In this equation D is the liquid diffusion coefficient, m is

the liquidus slope, k is the distribution coefficient (m<0 if k>l), V

is in cm/s and c is in w/o Cu.

oo

261
(b) Metastable Reaction Sequences in Multicomponent Systems

In a one component system, the molar free energies of the

phases can be used to rank the phases in a hierarchy of stability.

Reactions that convert a phase to one with a higher free energy are

forbidden. It has long been known that no such ranking of individual

phases is possible for multicomponent systems and indeed there is

experimental confirmation of theoretically predicted instances (because

free energy is reduced) in which stable phases dissolve in metastable

ones. The exploration of the kinds of hierarchies that follow from the

requirement that the free energy of the entire system can not increase

has led to the discovery of a rule that may be practical and lends itself

to the graphing on phase diagrams of lines or hyper-surfaces where the order

in the hierarchy of two stable or metastable states is. altered. An

exploration of the kinds of thermodynamic information needed and the various

practical methods of obtaining these is being explored.

(c) Glass Formation by Rapid Cooling of Eutectic Systems

Eutectic systems are multicomponent systems in which liquid remains

the equilibrium phase to low temperatures because no solid with

the same composition is stable. Because of the stability of liquid at

low temperatures these systems have been prime candidates for glass

formers by rapid solidification. The theory and practice of how rapidly

one needs to solidify has focused on the nucleation of the solid phase

as the difficult step in crystallization. In some systems theory is

clearly at odds with experiment.

We have focused instead on the growth problem. There are two

aspects being explored: 1) the thermodynamic question for each system

of the existence of a solid phase with the same composition as the

liquid which at some temperature below the eutectic becomes stable

relative to the liquid, 2) systems in which such a phase does not exist

can only crystallize into mixtures of crystals of differing composition.

The diffusional sorting of the components is a relatively well understood slow step which may govern the crystallization rate. These ideas

have led to a series of predictions for such systems which are being

explored experimentally.

For this purpose, experimental methods designed to solidify

eutectic alloys at known velocities up to 10 cm/s and temperature gradients

of 200 K/cm (cooling rate = 2000 K/cm) are being developed. This cooling

rate should be sufficient to form metallic glass in a few model alloys

( e - 9* > Pd-Si-Cu). Two methods are being pursued: 1) Rapid Directional

Solidification using the quenching of thin (<lmm) alloy filled tubes in

liquid Ga at controlled speeds, and 2) Electron Beam Surface Melting.

Both of these methods should permit quantitative determination of

solidification conditions which can be correlated to alloy microstructure (e.g. , eutectic spacing or glass formation).
Alloy Solidification: Solutal Convection

S. R. Coriell, W. J. Boettinger, and 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 the theoretical part of this research, the onset of coupled

convective and constitutional interfacial instabilities during the

directional solidification of a single phase binary alloy at constant

velocity vertically upwards (positive z-direction) is treated by a linear stability analysis. We consider a system for which the

temperature gradient alone would cause a negative density gradient and

the solute gradient alone would cause a positive density gradient. The

temperature and concentration fields are coupled through the hydrodynamic

equations. Because the usual solidification boundary conditions are

used at the sol id- liquid interface, the hydrodynamic and interfacial

stability phenomena are also coupled. Specific calculations were made

for physical properties appropriate to the solidification of lead

containing tin. Results indicate that the stability-instabil ity criterion

can differ substantially from the criterion of a net neutral density

gradient. For a temperature gradient in the liquid of 200 K/cm and for

velocities in the range 1-40 pm/s, a convective-like long wavelength

instability occurs at a critical concentration that increases with

velocity; whereas for V>40 pm/s, the concentration at which instability

occurs decreases as velocity is increased and the values of concentration

and wavelength at the onset of instability correspond to the predictions

of previous morphological stability theory which neglected density

changes and convection. Application of a vertical static magnetic field

increases the critical concentration for convective instabilities but a field of a tesla is needed to cause an order of magnitude change.

The occurrence of solutal convection and its effects on the microstructure and macrosegregation of directionally solidified alloys,

particularly off-eutectics, also has been investigated. During plane

front solidification the concentration of less dense solute is

increased in the liquid near the solid-liquid interface and there is

the possibility of solutal convection. In this year's research, the

effect of solute gradient induced convection on the macrosegregation of

Pb-rich Pb-Sn off-eutectic alloys during vertical solidification is

determined experimentally as a function of composition and growth

rate. In many cases macrosegregation is sufficiently great to prevent

the plane front solidification of the alloy. The transition from

dendritic to composite structure is found to occur when the composition

of the solid is close enough to the eutectic composition to satisfy a stability criterion based on G/V (temperature gradient/growth rate).

263
Interface Velocity Measurements

R. L. Parker

It is well known that a key variable in solidification processing

is the position and rate of motion of the sol id- liquid interface. Yet these

quantities are difficult to measure in opaque systems such as solidifying

metals. We have used an ultrasonic technique for i_n situ real-time measurement

of the position and motion of the interface in the directional solidification

of a low-melting metal (tin), and this technique should be applicable to many

metals, alloys, and other opaque materials processed by the metals industry

and the semiconductor industry.

The technique utilizes the fact that a sol id- liquid interface,

because of the differences in density and sound velocity of the two

phases, should act like a flaw to an incident ultrasonic beam, reflecting

a small but non-zero percentage of the incident energy. Thus the interface

should be able to be detected by modern ultrasonic flaw detection equipment.

The equipment uses a piezoelectric transducer which generates the pulse and

which receives the echo from the flaw. The transducer must be well

coupled to the liquid (or solid) metal using an appropriate coup! ant.

A standard pulser-receiver apparatus gives an oscilloscope display of the

out-going pulse and the return echo. With a knowledge of the velocity of

sound in the medium, the distance to the interface is read directly off the

screen, and as the interface moves, its velocity is obtained.

This technique has potential advantages for application to industrial

solidification processes, since it provides i_n situ real-time nondestructive

measurements. In particular, it could supply readings to an operator or control system without significantly disturbing the melt. In further work

on this technique we will explore the types of solidification problems to

which it can be applied, and the consequent knowledge and control of the

solidification structures thus obtained. An example might be continuous

casting of alloy ingots where the size and shape of the "mushy" zone during

solidification affect the microstructure and properties of the final ingot.

Surface Tensions and Their Variations with Temperature and

Impurities

S. C. Hardy and S. R. Coriell

The liquid-vapor surface tensions of many metals and semiconductors

are not well known and the temperature and concentration variations of

the surface tensions are even less certain. This is probably due in

most cases to the presence of unknown and uncontrolled surface active

impurities which may alter the surface tensions in complex ways. The ; objective of this project is to obtain reliable surface tension data by

controlling and characterizing these impurities. This seems to be a feasible goal because of the present availability of materials of very

264
high purity and the development of instruments and techniques such as Auger spectroscopy which can be used, at least in the case of low vapor

pressure materials, to analyze directly the chemical constituents at the

liquid-vapor interface.

In the past year we have measured the surface tension of gallium of

nominally 99.9999% purity over a wide temperature range using a sessile

drop technique in which the liquid drop rests in a shallow quartz cup in

order to assure a circular cross section. The gallium drops were contained in an ion-pumped vacuum system operating at vacuum levels around

10 9 torr. Above 200 °C the surface tension decreases linearly with

temperature with a slope of -0.068 mJ/m2 °C. Below 200 °C there is

significant curvature which is probably due to a surface active impurity

which is not being desorbed. Moreover, this low temperature behavior

depends on the previous high temperature treatment of the drop in a way

which suggests the gallium is being contaminated by some component of

the quartz cup. This matter is being investigated at present.

In addition, we have started measurements of the concentration of

impurities on a liquid gallium surface using an Auger spectrometer.

Initial results show oxygen and carbon persist in significant concentrations

even with heating to 350 °C.

Diffusion in Metals Data

D. B. Butrymowicz, J. R. Manning, and M. E. Read

Information about diffusion in metals and alloys is important in

many areas of science and technology. Industrial processes such as heat

treatments, use of protective coatings, sintering, welding, and gas/metal

interactions all depend on an understanding of, and quantitative data

for, diffusion. The NBS Diffusion in Metals Data Center provides a 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 answered. More than 22,000

papers reporting diffusion data now are on file. These references are

classified according to the alloys on which they contain data for ready

retrival. In order to handle this information efficiently, initial

steps have been taken to computerize the bibliographic and classification

data in these files.

In the past year, the first printing of the 322-page volume Pi ffusion

Rate Data and Mass Transport Phenomena i n Copper Systems was sold out.

The monograph was published by the International Copper Research Association

(INCRA) as part of the current activity. This handbook contains criticallyevaluated data for a considerable number of copper alloys. Funding for

the publication was provided by the trade association. To provide for a comprehensive collection of handbook data on these technologically

important alloys, new funding was granted by INCRA for a second volume.

265
Analyses are now being made of data not only for such large classes of

alloys as the brasses and bronzes but also of those elements crucial to

the smelting and refining processes of copper itself. Emphasis is also

being given to evaluation of transport phenomena related to the durability

of copper and copper base alloys. The attack and subsequent degradation

of these cast and wrought alloys through oxidation, sulfidation, etc.,

is one special concern of the second treatise.

Metals are frequently exposed to environments which change their

physical and chemical characteristics because of reactions between the

metal surface and the environment. Thus, the science and technology of

surface preparation to improve metal properties has gained much importance during the last decade. The bulk of these efforts have been

directed toward the modification of the surface through coatings. It is

with this in mind that the Data Center initiated an activity related to

high- temperature protective coatings on metals. A collection of diffusion

data in such systems was initiated this past year. Alloy systems con- taining the critical metal chromium are of direct interest to the present

activity.

A joint project with the Alloy Data Center on the compilation and

critical evaluation of data for candidate hydrogen storage materials

resulted in the publication in Hydrogen Energy Systems , Volume 4 (1978)

of "Numerical Physical Property Data for Metal Hydrides Utilized for

Hydrogen Storage," by members of both data centers. The three primary

materials, FeTi, LaNi 5 , and Mg2 Ni , were covered for eighteen possible

physical and chemical properties, including reaction rates, diffusion

coefficients, and other kinetic properties. Other materials, CuMg2 , LaCo 5 , and MgH2 , have also been evaluated, with data sheets for all

being sent to Lawrence Livermore Laboratory, where an on-line data base

for these materials is being established.

In another cooperative project, the Diffusion in Metals Data Center

is compiling a bibliography on selected titanium binary and ternary

alloys to assist the Alloy Data Center in determination of the best

phase diagram for a Ti-Al-Nb-Ta-Mo (6-2-1-0.8) alloy. Thus far, several

primary data-base searches have been done. They are being scanned,

requisitioned, and classified.

Diffusion Kinetics

J. R. Manning

The effective driving force for diffusion in alloys can be greatly

changed by defect binding and defect fluxes. Changes in driving forces

for atom diffusion produced by binding of vacancies in vacancy pairs

have been calculated. In addition, the effect of vacancy- i mpuri ty

binding on the atom flux originating from non-equilibrium vacancy

concentrations in irradiated alloys has been investigated. Significant

segregation can be produced by these non-equilibrium vacancy fluxes. It

is found that modifications of the diffusion driving forces by binding

effects often are large enough to change the sign of the resulting alloy

segregation. This result can be applied to control diffusion and

segregation in nuclear reactor alloys.

266
Descriptions of the driving forces were obtained first in terms of

effective atom jump frequencies and applied to situations where diffusion

occurs in the presence of electric fields. These fields and accompanying

alloy segregation effects are important in electric energy applications,

materials processing and electronic technology. The approach using

effective jump frequencies allows the complex atom motions in the

presence of electric fields to be related directly to well-established

diffusion correlation factor calculations. As a consequence, the

correlation factor values, whose magnitudes have been measured and

calculated in several important limiting cases, can be used to calculate

effective vacancy binding effects on atom drift velocities in electric

fields.

A similar method was used to calculate the effect of binding on the

redistribution of material in irradiated alloys. This redistribution

comes from diffusion of the vacancy and interstitial defects toward

surfaces and internal voids. The swelling of reactor alloys caused by

void growth limits reactor alloy durability. The growth of voids in

turn is strongly influenced by alloy segregation at void surfaces and

trapping of defects by impurities. Driving force differences leading to

the observed segregation were calculated from effective jump frequency

equations. In addition, binding conditions which would cause a reversal

in the sign of the alloy segregation gradient were determined from these

equations. These results for alloy segregation produced by non-equilibrium

vacancy concentrations can be related to the segregation effects which

occur when there are other driving forces, such as those produced by an electric field.

267
ALLOY PROPERTIES SCIENCE FOR STRUCTURE CHARACTERIZATION

The objectives of this task are to develop methods and standards

for the quantitative microstructural characterization of alloys to

optimize performance and to provide measurement methods, standards, and

data relating microscopic and submicroscopic structure to critical

engineering properties of alloys. Because of the increasing industrial

emphasis on quality control and automated processing, the technical

emphasis of this task is centered on the application of metal science

techniques to microstructural characterization methods. Thus there are subtasks using x-ray, eddy current, magnetic particle, positron annihilation, acoustic emission, and ultrasonic methods.

During the past year, task expertise in x-rays has helped make

available NBS access to the new synchrontron being built at Brookhaven

National Laboratories. CMS expertise in this field resides in this task

and a prototype instrument has already been built for carrying out realtime x-radiography at Brookhaven.

An automated x-ray system for nondestructive evaluation of surface

residual stresses has also been designed this year. This equipment will

be employed to improve measurement methods for surface residual stresses.

In the area of electromagnetic NDE, a new theoretical model needed

by ASTM E07.03 for magnetic particle testing was developed to describe

magnetic leakage fields and their relation to the formation of particle

indications on the much used ASTM magnetic particle test ring. This

model points the way to providing a quantitative standard practice for

transferring observations on the ASTM test ring to results on actual

parts.

In the areas of acoustic emission and ultrasonic characterization,

a new computerized facility has been configured and is being put together

to permit high speed ultrasonic and acoustic emission data acquisition

and processing. With the capability of communication with remote

computing facilities for the purpose of transferring data or utilizing

software. This will permit acoustic emission and ultrasonic studies of

such important metallurgical phenomena as ductile versus brittle mechanisms

for microcracking, martensitic phase transformations, texturing, and

secondary phase characterization. Our theoretical efforts in modelling

acoustic emission in a plate and in developing an experimental multichannel system for analyzing the tensor character of the acoustic

emission source will bring two guest workers from the United Kingdom

Atomic Energy Research Establishment, Harwell, to work with us in the

next year. Experimental work is beginning on acoustic emission from

indentation induced cracks in embrittled plates.

268
A new program supported by NASA in ultrasonic characterization of

soft spots in aluminum is also beginning. Initial work in this problem,

which has already caused some national concern, will involve the participation of Prof. R. Green of Johns Hopkins University. Longer range

activities in this area will center on providing better characterization

methods of critical microstructural parameters and their relationship to

aluminum processing so that more meaningful specifications can be provided

by the government and other purchasers of aluminum alloys.

Technical activities described in this task are:

Application of Synchrotron Radiation to Materials Science

Real-Time Radiographic System Performance Standards

X-ray Residual Stress Evaluation in the Interior of Materials

X-ray Diffraction Studies

Electromagnetic and Submicroscopic NDE

Acoustic Emission

Ultrasonic Materials Characterization

Scanning Electron Microscopy

Application of Synchrotron Radiation to Materials Science

M. Kuriyama, W. J. Boettinger, and H. E. Burdette

NBS and other scientific laboratories now have been invited to

develop research programs at the National Synchrotron Light Source, when

it goes into operation at the Brookhaven National Laboratory in 1981.

Hard radiation down to as short as 0.58 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 tuneability 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 tuneability, 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 transformation and structure stability, we have placed an emphasis

at the initial phase on the development of dynamic i_n situ measurement

capability to obtain an advanced knowledge in kinetics of microstructural

transformations. To achieve this, we have started developing real-time

topography with x-ray image magnification 1

. The prototype instrument

has been completed in our laboratory, awaiting a test at the synchrotron

radiation facility at the Cornell University. In addition, we have

performed an experiment concerning the polarization rotation effect in

materials using synchrotron radiation at the Stanford University2

.

269
X W. J. Boettinger, H. E. Burdette, and M. Kuriyama, Rev. Sci. Instr. 50,

26-30 (1979).

2 G. G. Cohen and M. Kuriyama, Phys. Rev. Letters, 40 957-960 (1978); to

be published in Phys. Rev. B, (1980).

Real-Time Radiographic System Performance Standards

M. Kuriyama, W. J. Boettinger, and H. E. Burdette

This is one of the Division's activities relating to the NBS NDE

program. This year's objective of this specific activity is to remedy

the confused situation in industry caused by the lack of performance

standards for real-time radiographic systems. Before proposing the

industrial resolution standards for radiographic diagnosis, the current

needs in industry demands the reevaluation of "radiography."

Currently the characteristics of a real-time radiographic system

are described by individual laboratories for their own convenience. The

resolution claimed to be attained by one laboratory using a single

isolated small object does not necessarily provide the desired resolution

for other laboratories which, for example, deal with a collection of

such small objects distributed in materials. In addition to resolution,

there are two other important factors for characterizing radiographic

systems: speed of obtaining diagnostic results and contrast (or detectability) of objects. There has not been a unified theoretical basis

for standards which can cover these three factors. The need of such

standards requires a possible unified method to describe the fundamental

characteristics of any real-time radiographic system. The feasibility

of this method is demonstrated using an actual x-ray source for a radiographic system.

The resolution of real-time radiographic systems is often considered

to be dominated by the resolution of viewing detectors. This is true,

if only one can prepare either a mathematical point source or a truly

parallel beam. In real-time radiography, detectors, unlike films,

cannot be placed in direct contact with or very close to object materials.

Thus the divergence of the beam, or exactly speaking, the apparent

source size cannot be ignored. The resolution of any radiographic (or

x-ray optical) system is intimately related not only to optical slit and

detector systems but also to the characteristics of x-ray sources. It

is, therefore, best to evaluate the quality of radiographic systems

including the radiation source as they are in use. The method proposed

is based on the following theoretical consideration. The source emits

radiation non-uni formly; the radiation from a point of the source has a different angular distribution (divergence) from radiation emitted from

different points. This non-uniform property, including different degrees

of divergence, is represented by I,-(x), where x indicates a point in the

source. The objective in evaluating the quality of optical systems is

to determine such an expanded quantity I<-(x) for the overall system as accurately as possible. For real radiographic systems, this quantity

I s (x) obviously includes the effects due to the slit systems before and

viewing detectors (image intensifies, films, or counters) after the

object.

270
Among many possible ways, we choose the two simplest modes of the

evaluation of I 5 (x). We use as an object a plate which consists of two

regions of different thicknesses. In mode I, this Heaviside object is

set at a stationary position and the intensity profile is obtained as a function of position. In mode II, the object is moving at a constant

speed, while the intensity is recorded at a fixed position in space as a function of time.

We have obtained an actual intensity distribution observed from our

radiographic system. Using a mini-computer on site, we can differentiate

the observed intensity to obtain I ? (x) and further to obtain the Fourier

transform of I s (x), which is the modulation transfer function (or more

exactly the optical transfer function.) Also, one can obtain the minimum

detectable image from this measurement. The details of the application

of this method including reproducibility, reliability, and easiness have

been documented in the past year. This technique also provides simultaneous information on the detectability of objects and the measure of

speed required for diagnosis.

X-ray Residual Stress Evaluation in the Interior of Materials

M. Kuriyama, W. J. Boettinger, and H. E. Burdette

This is another of the Division's activities relating to the NBS

NDE program. This year's objective of this specific activity is to

respond to an industrial demand for the evaluation of residual stresses

in the interior of industrial components, which often cause mechanical

failure in industrial products.

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 diffractometry. 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 methods, an obvious shortcoming lies in its incapability of detecting strains (or

stresses) in the interior of bulk materials.
Currently, improved quality control of industrial components demands

quantitative information concerning the stress distribution near cracks

and residual stress distributions after different types of cold working

and heat treating. These demands naturally lead to the necessity of

measuring residual strains in the interior of materials. Ordinary Bragg

diffractometry will not be sufficient to respond to these demands.

There is an entirely different approach to the x-ray evaluation of

residual strains although it uses the principles of x-ray diffraction.

This approach involves the use of energy dispersive solid state detectors

with high energy x-ray photons. The use of solid state detectors has

been introduced very effectively in the fields of scanning electron

microscopy (microanalysis) and x-ray fluorescence analysis of materials

in the past ten years. It is called energy-dispersive spectroscopy.

Unlike these successful applications, this technique has not been applied

to the residual stress (strain) measurements of materials. Extremely

high resolution and accuracy are required for strain measurements in

comparison with the other applications. If one can improve the resolution

sufficiently and overcome other important technical problems, this new system would be ideal for residual stress measurement in industry; the

equipment will be displayed visually and almost instantaneously, and

analysis of the data will be made on site by a computer. Also this

system, in general, works better for high energy photons. High energy

photons also make practical the use of the transmission geometry, since

the x-ray absorption coefficient of materials is approximately inversely

proportional to the third power of the energy of x-ray.

The use of an energy dispersive system for possible residual stress

evaluation was tested in 1973 by Leonard 1

, who concluded, however, that

this system did not have sufficient accuracy for this purpose. We have

proven that his conclusion was premature and it is still too soon to

dismiss the possible industrial use of this technique for the evaluation

of residual stresses. In doing so, we have proposed2

, 3 a method for

determining a strain tensor in predetermined volumes in the interior of

a material. One may claim then that the energy resolution of current

solid state detectors is not small enough to reduce the resolution for

the evaluation of residual strains. It has been known fortunately, that

each diffraction profile in the energy spectrum obtained from the solid

state detector is very close to a Gaussian. If the mathematical shape

is known for a spectral profile, then the claim mentioned above can be

circumvented: mathematically filling the observed peaks with Gaussian

functions, one can determine the centroids (or peaks) of the profiles

far more accurately than the AE/E value stated above would indicate.

Indeed, we have proven that one can improve by a factor of 100 in the

accuracy of determining the centroid positions. Our result demonstrates

that strains of 5 x 10 5 can be detected with reliable reproducibility,

insufficient counting statistics are established, and strains of 3 x

10 4 can be detected even with moderate counting statistics.

272
In conclusion, an energy dispersive diffraction system has demonstrated its capability as a useful tool for the determination of residual

stresses inside materials, when the curve fitting technique is used

simultaneously. The present demonstration has been carried out with low

energy photons. The use of high energy photons certainly makes more

practical the use of these energy dispersive systems for residual stress

evaluation. More penetration and increased energy resolution of detectors

will improve the resultant accuracy and detectability of strains. Since

the energy dispersive system can be made simple and compact, without any

delicate moving parts, the system is quite ideal for an industrial use

on site, particularly when data are handled by a mini -computer. By no means, has an energy dispersive system such as used here reached the

ultimate resolution; further improvements on x-ray optics and detectors

should be made, in particular, with high energy photons.

1 L. Leonard, Franklin Institute Research Lab (Philadelphia) Report

F-C3454 July (1973).

2 M. Kuriyama, W. J. Boettinger, and H. E. Burdette, ASNT National Fall

Conference, October, Denver, Colorado, p. 49 (1978).

3 M. Kuriyama, W. J. Boettinger, and H. E. Burdette, Symposium on Accuracy

in Powder Diffraction, National Bureau of Standards, June (1979).

X-ray Diffraction Studies

C. J. Bechtoldt

The use of conventional surface x-ray techniques is an indispensible

part of any microstructural characterization effort on metal alloys.

Two main research projects are currently being undertaken in this area

along with a considerable amount of support service. The processing of

titanium-aluminum alloys for durability is hampered by inadequate knowledge of the Ti-Al phase diagram. Many conflicting reports are in the

literature as discussed in the Metallurgical Chemistry of Durability

Task. Part of the problem is the incomplete characterization of carefully

prepared Ti-Al alloys.

Initially, we will carry out phase identification in these alloys

by quenching- in the structure and examining the specimen by x-ray

diffraction. Measures will also be taken to identify the phases at

temperature by high- temperature x-ray diffraction which has not been

done before. The room temperature study has the advantage of permitting

higher magnification and resolution and sharper lines in the diffraction

patterns, but quenching to room temperature carries the risk that the

high-temperature phases will not be retained. It has been pointed out

in the literature that to settle the controversy between investigators,

the observations must be made at high-temperature to avoid any possibility

of the phase transformation upon quenching to room temperature.

The second research project concerns development of improved

techniques for more accurate measurement of surface residual stresses.

An automated x-ray data acquisition system has now been configured and

is now out for bid, and some of the newer, more promising techniques

will be critically evaluated and compared with the SAE standard method.

273
Studies have also been made by x-ray diffraction on the texture and

precipitations in beryllium used in qyroscopes in cooperation with the

Fracture and Deformation Division. No appreciable texture was noted but

up to five different precipitates were identified in this grade of

beryllium using non-conventional Debye-Scherrer methods.

Studies continued in the principal area of characterization of

metals and alloys as used in several other projects in this Division and

other activities at the Bureau. This included such problems as the

study and identification of phases of compounds resulting from corrosion;

the precision measurement of lattice constants; qualitative and quantitative determination of minor and major phases in metal alloys used in

research problems; determination of degree in ordering in alloys,

determination of grain size, residual stress, nature of twinning, and

the orientation of single crystals or large grains in metals or alloys;

x-ray diffraction, ordering, and' lattice constant studies on Ti-Al

alloys as part of this Division's activities in that area.

Most alloys prepared in the Specimen Preparation Laboratory, purchased on the outside or donated are submitted for characterization by

x-ray diffraction studies and measurement of the lattice constants where

appropriate. These studies include metal carbides and metal phosphites

as pure substances or mixtures or with added impurities. These studies

include identification of phase present, lattice constants, and grain

size. Lattice constants and degree of ordering were studied in Ni 3 Al

alloys where part of the aluminum was substituted with another metal.

X-ray diffraction studies were made on dental amalgams, Cu-Sn phases,

and in the Pd3 (Si-Cu) system. Over 80 diffraction patterns were made on paper products or fillers used in paper products.

Electromagnetic and Submicroscopic NDE

L. J. Swartzendruber, R. C. Reno, J. R. Cuthill, and L. H. Bennett

Magnetic particle NDE is a relatively simple and inexpensive, yet

effective and rapid method. It has extensive use for both production

and field testing of ferromagnetic components. Despite its apparent

simplicity, a large number of variables influence the inspection process

and need careful control in order to obtain repeatable and reliable

results. Obtaining a sound scientific basis for properly controlling

these variables is the purpose of this project. For testing particle

sensitivity the use of standard test parts has been recommended, and a number of these are currently being included in general specifications

for magnetic particle inspection processes. However, the extent to

which such test parts evaluate the properties of the particles being

used rather than a combination of operator skill, proper magnetization

levels, proper particle densities, and other contributing factors, is

poorly understood. An evaluation of the importance of the various

contributing factors requires the development of a mathematical model to

describe the formation of magnetic particle indications. An important

step in this development, obtaining a suitable description of the magnetic

leakage fields from sample defects and how they influence particle

motion, is currently under investigation.

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One test part currently under extensive use is in the form of a ring with cylindrical defects. Because of the non-linearity of a ferromagnetic material, an exact description of the leakage fields from the

defects in this ring poses formidable mathematical difficulties. However,

we have shown experimentally that, to a good approximation, a simple

linear dipole model can be used to describe the leakage fields provided

that a proper equivalent depth which is less than the true depth, and a proper value for the effective dipole moment per unit length are used.

Using the leakage field description model as described above, a simple model taking into account only leakage field and gravitational

forces was investigated. This model showed clearly, in quantitative

terms, the importance of particle shape and surface mobility in forming

magnetic particle indications. Using the observed leakage field strengths

and the known number of defects that form indications on the test ring

at various current levels, a detection criterion could be stated in

terms of the force experienced by an isolated spherical particle. An

extension of this criterion to other situations would be very useful and

might allow the calculation of required magnetization levels and detectable defect size, parameters which must not be determined empirically.

The utility of Doppler-broadened position annihilation line shape

measurements as an NDE tool is being investigated. Lineshape measurements have been used to study defect behavior in titanium samples which

were first cold-worked and then annealed at temperatures ranging up to

850 °C. The lineshape as a function of annealing temperature was used

to show that a simple lineshape parameter can be used to reflect changes

in the defect structure, including changes that occur well below the

recrystall ization temperature that are not detected by hardness measurements. Thus measurements of this parameter might be useful in monitoring processes that occur in titanium both prior to and during recovery

and recrystall ization.

The production of standard metal blocks for the calibration of eddy

current test equipment is being investigated. This work is being carried

out in cooperation with the Electrical Measurements and Standards Division.

Four aluminum alloys have been selected for use in these standards. The

Metal Science and Standards Division will supervise the fabrication of

the standards,. Each standard will be individually calibrated by the

Electrical Measurements and Standards Division. Personnel from this

task are also serving on the Organization Committee for the joint NBS/

ASTM/ASNT/IEEE Eddy Current Symposium to be held September 1979.

Acoustic Emission

J. A. Simmons and 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 microstructural 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

275
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.

This activity is part of the joint EPRI/NBS program on acoustic

emission whose overall objective is to provide the electric power

industry with the technical basis for deciding whether or not to incur

the costs of flaw monitoring systems based on quantitative analysis of

detailed AE signals. Aside from providing theoretical guidance and

metallurgical assistance to all tasks of the NBS/EPRI program, the Metal

Science and Standards Division contribution to this program may be

divided into four parts: (1) to develop the theoretical basis for

describing acoustic emission from moving defects; (2) to develop experimental procedures and test methods for obtaining reproducible quantitative

acoustic emission signals in structural metals, e.g. , pressure vessel

steels; (3) to develop data processing techniques to permit analysis of

acoustic emission signals from structural flaws; and (4) to assist the

technical community in the development of calibration and interpretation

standards and procedures in acoustic emission.

Work in the theory of acoustic emission has itself been divided

into four parts:

i) Deriving the transfer function formalism

ii) Dealing with the plate geometry

iii) Signal processing and deconvolution

iv) Modelling AE from defect sources.

signal received at a given transducer in terms of a transfer function

containing the material geometry and transducer characteristics and a

i) The transfer function formalism which may be summarized

by the equation

V(uj) = T (uj)cr %)

allows one to express the voltage frequency response from a given AE

signal received at a given transducer in terms of a transfer function

containing the material geometry and transducer characteristics and a

•A mean stress drop tensor, ct , associated to the emission event. The

transfer function representation is not generally valid, but requires

both restrictions and assumptions. However, it appears likely that this

formalism may well be valid in many technological important applications.

If one wishes to invert the AE information to find the source

stress drop tensor, the transfer function formalism leads to certain

important implications. 1) Unlike scalar transfer function problems

where inversion information can be obtained directly from power spectra,

*A

to find ct from V(tu), multiple transducers yielding complex spectra with

phase information are generally necessary. Generally, six separate

observations are needed to separate the six stress components. 2)

Bandpass filtering to eliminate the defect size effect may also be

required, which, together with other filtering to eliminate noise, can

at best yield band limited information about the source.

276
ii) In order to be able to experimentally verify new measurement concepts for quantitative acoustic emission, one must have a detailed

understanding of elastic wave propagation in a structure on which

acoustic emission experiments can be performed. The two geometries for

which this is realistically possible are the plate and the tube. The

plate geometry was selected and a solution for elastic wave propagation

in an isotropic plate has been developed in collaboration with Prof.

John Willis of Bath University, England. This solution, based on a new Fourier transform technique, allows one to compute the transient response

in an elastic plate due to various stress sources located up to about

ten plate thicknesses from the detector. Study of the dipole source

characteristics indicate the possibility that in addition to obtaining

detailed information about an acoustic emission source whose exact

position is known, the depth of some types of technologically important

sources may also be determinable. Other theoretical consequences of the

plate solution are being studied including calculating the effects of

high frequency attenuation due to averaging over transducer faces.

iii) In order to invert the signals received from the transducer

to obtain information about the AE source, it is necessary to carry out

a numerical deconvolution procedure. A formally similar deconvolution

procedure is required to produce a transducer calibration. Because of

the high priority associated to this latter need, work was temporarily

suspended on the plate solution results to look at deconvolution algorithms. Most of the ordinary algorithms in use today were found to be non- robust, frequently yielding incorrect or ridiculous answers to

deconvolution with the type of signal needed for transducer calibration.

The problem occurs because of numerical noise amplification produced by

deconvolution algorithms. Three new algorithms were developed. One,

based on an FFT type algorithm, was supplied to the Mechanical Processes

Division where AE transducer calibration is being carried out. The

other two require more extensive computer facilities. One of these

methods is being explored for signature analysis potential. The third,

developed in cooperation with Dr. Diane O'Leary at the University of

Maryland, is still being studied. Since there are a great number of

fields where deconvolution is used, the importance of these new algorithms

extends well beyond acoustic emission.

iv) The theory for acoustic emission from expanding planar

dislocation loops has been developed.- In an infinite body, only three

qualitatively different types of response function are obtained, two for

prismatic collapse type of dislocation loop generation (looking at the

dislocation from different directions and monitoring different displacements) and one for slip type loops. Typical values for dislocation

loops in metals show that a rapidly nucleating loop of 3 pm diameter,

for instance, produces displacements of the order of 10 13 cm at a distance of 10 cm. Thus it is clear that acoustic emission events for

single dislocations are undetectable and that sources approximately

1

0

13— 1

0

4 times as strong are required.

In order to improve our capabilities in experimental metallic

microstructural characterization by acoustic emission methods, Roger

Clough, formerly of the Mechanical Processes Division, where most of the

277
transducer calibration work is being carried out, has transferred into

this task while Nelson Hsu, in turn, has transferred to the Mechanical

Processes Division. The data acquisition system that Dr. Hsu was using

has also gone over to the Mechanical Processes Division, and a new completely reconfigured minicomputer based high speed data acquisition

and processing facility more appropriate for tests involving complex

microstructural emission phenomena is being installed. The laboratory

facilities have also been remodeled, and a new facility for ultrasonic

characterization of materials has been added.

The need to study real defects as opposed to simpler calibration

type sources introduces a number of requirements due to the generally

lower signal level of real defects and the tensor nature of the defect

signal. The high speed data acquisition system and its associated minicomputer system are now being procured. Low noise preamplifiers are being built to directly mount on the back of well characterized capacitative transducers each of which will be recorded by a separate high

speed analog to digital converter (only one A to D converter is currently

available). The current A to D converters have only 8 bit resolution

with concomitant lack of dynamic range, and we are currently studying

means for increasing the dynamic range if needed. The outputs from the

analog to digital converters are dumped at very high speed into a remote

high speed peripheral making it possible to record multiple emissions in

a single test ip a laboratory environment separated from the computing

facility.

We have chosen to study experimental acoustic emission signals in

steel plate specimens, and we are currently studying indentation loading

methods under a variety of conditions to select the most promising

experimental configurations. Our goal is to study microcracking under

controlled conditions where the cracking mechanism will vary from ductile

to brittle. While not yet fully evaluated, brittle type cracks have

been produced at the surface in the heat-affected zones of welds (both

continuous and spot) and in high carbon steel which was given an em- brittling heat treatment.

ASTM interaction continues strongly with the vice-chairman of ASTM

E7.04 coming from this program. Interaction is also quite active with

the Theoretical Physics Division and the Nondestructive Testing Center

at the A.E.R.E. , Harwell. We expect two visitors next year from Harwell,

Dr. H. Wadley, to do experimental work using our new multichannel instrumentation for determining the tensor character of AE sources, and Dr. J. Sinclair, to study our solution for waves in an elastic plate and to

convert our computer programs to be usable on the Harwell computer.

Ultrasonic Materials Characterization

J. A. Simmons, D. E. MacDonald, and R. B. Clough

This is a new activity using ultrasonic techniques for nondestructive^ 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,

278
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, porosite, 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

is beginning on ultrasonic characterization for soft spots in aluminum

alloys. Due to what appears to be an improper quench procedure, incorrect

second phase precipitate distributions have been produced at unknown

spots in the fabrication of a variety of high strength aluminum alloy plates

used in aerospace applications. In some cases, these spots have their

ultimate tensile strength reduced by 70 percent. The first priority

question here is to develop a reliable NDE method for detection of these

soft spots. Velocity, attenuation, and ultrasonic scattering techniques

will be 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.

Work has also been carried out on the application of ultrasonics to

residual stress measurements. When the elastic constants of material

are changed such as occurs when the material is heated or stressed, the

changes in these constants can be induced by precise velocity measurements

from which information on the material state can be inferred. This

technique has great promise for the measurement of residual stresses and

has been used in a number of applications. However, few formulations

have taken into account the simultaneous dependence of the velocity on stress and strain such as occurs in thermally stressed materials. This

separate dependence on stress and strain has been demonstrated with the

aid of a mathematical model used to find the effect of finite strain on the wave velocities. For shear waves with either the propagation direction or the displacement direction parallel to the maximum principal

stress, the change in the wave velocity results from nearly equal but

opposite contributions from the stress and from the strain dependent

modul i

.

These findings, for instance, have application to determining the

longitudinal force in continuously welded rail. The constrained configuration of the rail results in the development of buckling forces

during temperature increases. The absence of any longitudinal strain

greatly modifies the balance between the stress and strain contributions

to the velocity. This enhanced stress dependence of the velocity may

provide a way to nondestructive^ determine the longitudinal force in

continuously welded rail.

The direct stress dependence of the ultrasonic velocity reflects

the fact that wave propagation in stressed material is fundamentally

different from the stress-free case with the related symmetry. A

comparison of wave speeds for materials with isotropic, transversely

isotropic, cubic, and tetragonal symmetry and these same materials under

279
tri -axial stress has been made which indicates how to separate the

effects of stress and texture. This information can be applied to the

problem of determining the residual stresses in unidirectional metal

matrix composites.

Scanning Electron Microscopy

D. B. Ballard

The IR-100 award winning SRM 484 magnification standard for scanning

electron microscopy has been one of the most successful in the SRM program. A reissue of 250 samples was made available in March of this year

at which time there were already 85 units backordered. As of late

August, 124 samples have been sold, including several overseas.

The problem of edge seepage and new encapsulating techniques has

been tentatively solved. Removal of seepage and contamination can be

removed by sputter plasms etching in an argon atmosphere or by stripping

a dried cellulose acetate replica. A new procedure for incapsulating

the Au-Ni composite consists of mixing tin powders of 1-5 pm and 500 pm

size into epoxy resin and centrifuging the casting at 24,000 G for two

hours. The required electrical conductivity and surface bonding seems

to be satisfactory.

Copies of Draft #3 “Recommended Procedure for Calibration of the

Magnification of a SEM Using NBS-SRM-484" have been approved by E-4 ASTM

for review by Subcommittee XI (Electron Microscopy).

The SEM laboratory and associated equipment has continued to provide

support to NBS personnel who have used the facility for over 850 hours.

Several requests for training of new operators have been fulfilled and

consulting services have continued. A cooperative student position in

this laboratory has been provided that allows back-up operation of the

facility when the manager is absent. The SEM facility has been used by

the senior researcher to support other research activities at NBS. Some

examples of activities this year are as follows.

Thin electrodeposited gold plating is used in industry as decorative

coatings, in electronics as a conductive film, and in space for ultraviolet

reflective protection. Accurate measurement of thickness less then 1 pm

are essential for optimum efficiency and economical use. Using the

availability of the SRM-484 (SEM Magnification Standard) and properly

prepared cross sections of specimen accurate measurements of thin gold

plating coatings were made to 10 percent or better. A paper "Thickness

of Gold Coating Measured with a Calibrated SEM" describing the techniques

used and results has been written for publication.

A section of the fracture surface that included weld metal from the

replacement bridge for the Silver Bridge across the Ohio River was submitted by the Fracture and Deformation Division to ascertain the mode

and mechanism of fracture. Fractographs and x-ray spectrograph results

were included in the reported analysis. A paper on this investigation

is planned.

280
Urea- formaldehyde foam is used as a thermal insulation in existing

housing structures. Under certain conditions of temperature and humidity

this material loses its desirable properties. An SEM examination of as- formed and of field and laboratory degraded samples submitted by Structures

and Materials Division revealed changes of cell structure. The SEM

results will be the basis for an intended report and later publication.

The results obtained from the SEM examination of six different

solar panels on details of surface texture, thickness, corrosion products,

and degradation mechanisms was incorporated in a paper to be submitted

for publication. This information is of particular interest to the

paint and solar energy community.

A combined effort within the Metal Science and Standards Division

is to redetermine accurately the Titanium- Aluminum Alloy Phase Diagram.

The SEM has been used to study the observed phases, results of hardness

impressions, x-ray spectro analysis, and fractography of preliminary

alloys.

Micrographic studies and minor phase analysis are also planned as part of the Division's effort in the soft spots in aluminum problem.

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ALLOY DURABILITY FOR WEAR AND IMPLANT APPLICATIONS

The provision of data and understanding concerning the durability

of materials in service is one of the principal technical thrusts in the

Center for Materials Science. This task is concerned with the wear

durability of alloys and with the application of metals as synthetic

implants, principally orthopedic implants.

The wear activities have involved research into the mechanisms of

metal wear under dry sliding, abrasive, and solid particle erosive wear. Efforts have continued to develop and improve test methods that address

the anti -wear characteristics of oil lubricants with emphasis on re- refined motor oils. A major NBS conference is this area has been organized for Fall 1979. Highlights of the ASTM standardization work in the

past year include the development of abrasive wear and erosive wear test

methods. The post of vice-chairman of ASTM-G2 on Erosion and Wear will

involve many wear standards activities as well as long-range planning

for this Committee. NDE activities in the wear condition monitoring of

systems have continued with some significant developments in standardization areas. A budget initiative in wear will be implemented in FY80

to develop research into areas of fatigue wear, fracture effects, and

environmental aspects of wear. Several staff additions will result from

this initiative. We have also agreed to serve as Program chairman for

the Third International Wear Conference in 1981.

The projects concerning alloys used in synthetic implants have

continued to concentrate on corrosion and the fatigue behavior of several

relevant alloys. Two new areas of investigation have started on fretting

wear of implant alloys and on the chemistry of metal-organic reaction.

Fretting is a potential source of metallic particles in the body; the

characteristics of such particles and the potential hazards must be

determined. Experiments studying the chemistry of metal reactions in

organic solutions that simulate body fluids have begun involving a new staff member. Standardization work in ASTM-F4 has involved a new method

for wear testing of implant materials and planning for a major NBS

Symposium on Retrieval and Analysis of Implants to be held in 1980. The

technical activities in this task (described below) are the mechanisms

of metallic wear, wear standardization, wear NDE activities, lubricated

wear, and metals used as biological implants.

Technical Activity

Mechanisms of Metallic Wear

A. W. Ruff, L. K. Ives, S. Bushby, and P. Boyer

It is often said that there is little understanding of the influence

of materials properties on wear behavior. Indeed, the past development

of alloys to resist wear has proceeded mainly on an empirical basis.

Thus when improved materials are required or new conditions are encountered, there is little in the way of fundamental knowledge to guide or assist in the development and design process.

282
The purpose of this project is to improve the understanding of

basic wear mechanisms. Particular attention has been focused on the

relationship between the microstructure of metals and the wear process.

The approach has been to expose carefully prepared specimens to a variety

of wear conditions using simple laboratory devices. The specimens and

the wear debris are then characterized, principally by means of scanning

and transmission electron microscopy. In this way, surface topography,

subsurface microstructural changes, and wear debris characteristics can

be related to exposure condition. The morphology of wear debris fragments is often found to be a valuable indicator of the wear process. In

previous work, copper (99.99 wt.%) was exposed to solid particle erosive

wear and the significant processes were determined. During the past

year, a study of copper exposed to three body abrasive wear, dry sliding

wear, and lubricated sliding wear was carried out. The results of this

investigation were reported in a paper delivered at the International

Conference on Wear of Materials held in Dearborn, Michigan. Additional

findings were presented at the annual meeting of the Electron Microscopy

Society of America in San Antonio, Texas. Certain features were found

to be characteristic of the different types of wear. For example, the

high strain rates associated with particle impact in erosive wear lead

to deformation twinning. Twinning was not observed in connection with

other types of wear in which the strain rates were much less. Common to

many types of wear contact, however, was the transition from a dislocation

cell structure to large depths below the surface to a layer of highly

misoriented often elongated subgrains. Depending on the contact stress

and type of wear, the thickness of this layer was 5 to 10 pm. A large

fraction of the plastic strain that occurred was accomodated in this

layer. It was also from this layer that wear particles are generated.

Plans for next year will include studies of the details of the microstructure that develops within the first few micrometers of the worn

surface and on the structure of wear debris fragments. In this way,

insight may be gained on the relationship between wear debris particle

generation and microstructure. It also appears that the crystallographic orientation texture that develops at worn surfaces can be influenced by contact stress, sliding velocity, and temperature. By studying

the orientation textures, information can be obtained on. the dynamic

processes, for example, local thermally induced recrystallization, by

which the textures are produced. An extension of this work to copper

alloys of significance in bearing applications as well as certain bcc

and hep metals, probably iron and cobalt, is planned. A new contract

from the Office of Naval Research has been received to further extend

our studies of wear mechanisms. There the relationship between macroscopic mechanical properties such as strain hardening and ductility with

wear performance will be examined for several steels and other metals.

Another phase of this project is concerned with the wear of coatings

on metals. Support from the NBS Director's Reserve Fund has permitted

starting a new effort. Coatings of all types are widely used in industry

to extend the durability of materials with regard to wear and corrosion.

Coatings also permit the substitution of materials, in particular, the

283
conservation of strategic metals. Our work has focused on metal coatings

and their wear performance. A new wear test facility was designed,

constructed, and applied to studies of chromium, nickel, and electron

beam melted coatings. The wear tester is computer controlled and the

system provides continuous output of wear rate, friction, temperature,

load, and speed. Software has been developed to start, control, and

terminate the tests according to a variety of criteria. Dry sliding

wear studies have shown that electroless nickel coatings can provide

significant wear resistance on steels. An electron beam apparatus has

been developed (in collaboration with F. Biancaniello) to surface melt

and rapidly solidify tool steel and stainless steel specimens. These

rapidly solidified layers (coatings) have an extremely fine microstructure

and show an increased wear resistance relative to normal thermal treatments

of the base materials. Further studies in the mechanisms of wear in

rapidly solidified coatings and other materials are planned for next

year.

Wear Standardization and NDE Activities

A. W. Ruff, and L. K. Ives

Standardization activities involve the ASTM Committee G-2 on Erosion

and Wear as well as the NBS Office of Standard Reference Materials.

Work in the G-2 Committee involves the Vice-Chairman post concerned with

overall committee work and long-range planning as well as four subcommittees.

We are responsible as chairman for the Editorial subcommittee and the

Terminology subcommittee. In two technical subcommittees, wear and

solid particle erosion work is underway involving project staff on two

test methods. The first test method under development is concerned with

the abrasive wear of materials. The test employes a rotating rubberfaced wheel to rub loose Si02 particles against a specimen and is known

as the dry sand/rubber wheel (DS/RW) abrasion test. The DS/RW test

addresses a form of wear that is probably one of the most costly and

prevalent, being predominant in industries concerned with moving ore,

and excavation, to name a few. The ASTM DS/RW task group has reached

the final stages of preparing a standard test method. Our contributions

have been to the standards writing activity, to round robin test exercises

and to improving the test procedure itself. There are several aspects

of the test that can lead to serious systematic errors. For this reason,

it is deemed necessary to develop one or more standard reference materials

to be used as test specimens. We are presently evaluating 1020 steel

for this purpose. The second method concerns solid particle erosion

testing of materials where a draft standard has been developed and two

cycles of round robin measurements are completed. A standard reference

material (1020 steel) is being developed in this project for use with

the method for the first time. These efforts should lead to a greatly

improved measurement capability for wear and erosion and encourage the

development of improved wear resistant metals. A new effort has begun

in G-2 concerned with reference methods for wear debris analysis. About

10 industrial and government laboratories have indicated that they plan

to be involved in this developing activity.

284
This project is also concerned through the NDE program with the

nondestructive monitoring of the operating capability (health) of

mechanical systems in which wear is a significant lifelimiting process.

This monitoring can take several forms in the field, e.g. , measurements

of system operating parameters (temperature, speed, pressure, or vaccum,

etc.), vibration monitoring of rotating machinery, and the recovery and

analysis of wear debris. The Navy Department has led in many of these

developments although all such programs now extend throughout the DoD.

These methods generally extract the wear debris from oil lubrication

systems and provide a nearly continuous measure of wear metal formation

rate. The debris method is frequently combined with spectrochemical

methods of oil analysis in the diagnosis of system condition, although

the two methods are sensitive to wear products in a different way.

Debris can also be recovered from non-oil-lubricated systems, e.g., gas

turbine engine ducts. Some of these techniques are being applied in the

private sector, e.g., several major airlines and truck fleet systems.

Relatively little understanding exists of the trends in wear characteristics and in debris generation mechanisms. The project is oriented

to assist in these problem areas through method development, the provision

of fundamental understanding, and assistance in standardization activities.

We are studying wear debris formation mechanisms in steel and copper

metals. The emphasis has been on rubbing (adhesive) wear and on abrasive

wear. Abrasive wear is a major cause of failure in lubricated systems,

generally the result of particulate contamination from outside the

system (seal problems) or from recirculation of wear debris particles

(filter problems). We have examined the type of wear debris removed

from steel surfaces under various abrasive conditions. Particle size

and shape distributions have been obtained. In the case of wear of

copper (whose alloys form the usual commerical bearing materials), wear

debris studies have been combined with surface and subsurface microstructure studies. Findings include the tendency for abrasive particles

to fragment and become imbedded in the ductile metal surface. The

identification of cutting chip particles in debris collections does not

appear to be a satisfactory indicator of system wear mode. In fact,

many debris particles are produced by plastic deformation processes

during abrasive wear and must be distinguished from normal rubbing wear

particles. Plans for next year include the acoustic monitoring of wear

systems in order to correlate that information with the debris recovery

data.

Lubricated Wear/Recycled Oil Activities

L. K. Ives, A. W. Ruff, K. Ludema, M. Peterson, and P. Boyer

This project is supported by the Recycled Oil Program. Its objectives are to evaluate available laboratory wear bench tests for determination of the consistency and the wear behavior of recycled base

lubricating oils and to develop additional laboratory wear bench test

procedures that can be used for this purpose. It is necessary to recycle

used lubricating oils both for resource conservation purposes and to

protect the environment from pollution. Section 383 of the "Energy

285
Policy and Conservation Act of 1975" directs the National Bureau of

Standards to develop test procedures for the determination of substantial

equivalency of re-refined used oils with new oils. The intention of

this law is to remove present restrictions that constrain the recycling

of used oils, including motor oils and a variety of industrial oils.

This project is concerned entirely with automotive engine oils. Tests

to evaluate the properties of lubricating oils may be categorized as chemical, physical, or performance tests. A wear test is essentially a performance test that is more or less responsive to some or all aspects

of the lubricant. The wear test may employ the actual machine for which

the lubricant is intended, a single component of the machine, or rubbing

elements that bear no particular relationship to the machine. There are

several ASTM standard test methods which employ bench wear test machines

that can be used for evaluating motor oils. Three different machines

known by their specimen geometries are used in the ASTM tests. They are

the pin and V-block, the block-on-ring and the 4-ball test machines.

All of these machines are widely used in laboratories of companies that

produce lubricants or evaluate lubricants for use in their machinery,

including the automobile companies.

Each of the test machines mentioned above has been acquired by the

Recycled Oil Program for evaluation. Two of these machines, the pin and

V-block and block-on-ring machines are being examined by this project.

Evaluation of the ASTM Standard Test Methods employing the pin and Vblock machine has been completed and other modified procedures carefully

examined. It appears that the pin and V-block machine will be of limited

applicability with respect to oils.

Evaluation of test procedures using the block-on-ring machine are

underway. Due to the inherently greater precision and flexibility of

this machine, it may offer some advantages over the pin and V-block

machine. In evaluating the significance of bench wear test methods,

consideration must be given to the nature of the wear process itself.

The closeness of the coupling between bench test results and service

performance will depend on the extent to which the wear processes are comparable. Many features of the wear process may be revealed through

an examination of the worn surface and the debris fragments that are generated.

A scanning electron microscopy study of worn engine components and

bench test specimens has been initiated. The engine components were

obtained from the Southwest Research Institute and had been used in oil

qualification sequence tests. A similar investigation of wear debris

particles is planned. A literature survey of lubricant wear testing has

been carried out and an evaluation of literature reports on failure

modes in engine components is being conducted. The project plan includes

close coupling between actual component metallurgy and wearing conditions

with bench test metallurgy and conditions in setting the proper context

for examining re-refined base oil consistancy, additive interactions,

and impurity effects through wear bench testing.

286
A fall conference of the Mechanical Failures Prevention Group,

jointly sponsored with the Recycled Oil Program, will address many of

these issues including oil analysis, wear and fatigue durability, and

bench testing methods.

Metals Used As Biological Implants

A. C. Fraker, A. W. Ruff, K. M. Speck, G. J. Mattamal , and

M. A. Imam

The use of metals in the body is increasing steadily. Some applications are in orthopedics, dentistry, and heart pacemaker cases. There

are many problems with these applications that require a much better

understanding of metals as synthetic implants. The purpose of this

project is to study implant metals and relate their properties and re- activity to the requirements for the various uses in the human body.

The emphasis of this work falls into five primary areas which are closely

interrelated. These are (1) corrosion, (2) corrosion-fatigue, (3) wear

and fretting, (4) metal -organic reactions, and (5) standards activities,

and are described in the following paragraphs.

Corrosion - Personnel in this project also include Dr. Pei

Sung, guest worker from the FDA, Dr. Heiner Weber, a West German dentist

who was a guest worker in the NBS Dental and Medical Materials Group,

and Jocelyn Orbock, a cooperative student from the College of Notre

Dame. The project is studying the chemical reactivity and electrochemical

behavior of implant metals, dental amalgams and casting alloys to determine possible metal ion loss to the body environment, and degradation of

the metal. Anodic polarization measurements were conducted to provide a means of evaluating materials in terms of their passivity and film

breakdown. The effects of coupling different implant metals and various

alloying additions were studied with this technique and using scanning

electron microscopy. Repassivation studies are underway to establish

the kinetics of film formation under various conditions. We participated

in an ASTM round robin pitting corrosion test and conducted a number of

tests in this regard. Three publications and two talks resulted from

these studies.

Corrosion-Fatigue - This is a cooperative program involving

Prof. Charles M. Gilmore of the George Washington University. The

fatigue life of implant metals is measured under fully reversed torsion

conditions in prepared physiological solution at 37 °C. Effects of

material microstructure, frequency, and load are considered. Most

alloys have been obtained from implant manufacturers for testing and the

results have been presented at professional society meetings. This past

year, these results were presented in three talks, one publication, and

will appear in another publication which is in preparation. Recently,

studies have begun on a new improved cobalt-chromium alloy in the forged

high-strength condition. Another material being currently studied is a relatively new titanium alloy, Ti-4.5Al-5Mo-l.5Cr (Corona 5). In conjunction with fatigue testing and electron microscopy studies of these

metals, an effort is being made to separate the mechanical and chemical

factors and to determine mechanisms of corrosion-fatigue under these

conditions.

287
Wear and Fretting - In cooperation with Dr. Ian C. Clark,

University of Southern California, a recommended wear test procedure was developed, and it is now in its second subcommittee balloting by the

ASTM Committee F4 on Implants. Laboratory apparatus has been designed,

and an automated, programmable data collection system has been assembled

for conducting tests to study fretting wear rates and mechanisms.

Variables to be considered in this work are the environment (pH, temperature, etc.), load, frequency, alloy composition, and surface coatings.

This work will involve electrochemical and mechanical measurements,

surface changes, and fretting debris production. We are formulating a joint program with Dartmouth Medical School to examine the effects of

fretting wear debris.

Metal -Organic Reactions - This is a new phase of our implant

project. A laboratory has been set-up to investigate whether and how

much of a given metal ion will be carried by blood serum albumin. This

will be followed by experiments to determine specific proteins to which

the metals attach. Currently two cells with porous membrane filters are

in use. The metal ion content is determined by atomic absorption.

Metal ions to be studied initially are those of copper, nickel, and

titanium. Later, this work will be oriented toward our corrosion and

metal ion release studies.

Standards Activities and Interactions - One of the important

aspects of this work is assisting with the development of standards for

the ASTM. Current responsibilities in the ASTM include serving as chairman of the F4.2.5.17 wear test task force, co-chairman of the joint

F4-G1 Corrosion Section, and as liaison between F4 and G2 in the area of

implant materials wear. Excellent cooperation with the NBS Medical and

Dental Group continues as indicated earlier. There are numerous industrial

and other outside contacts. Recently, we teamed up with people from

Artech Corporation, The George Washington Medical School, and the George

Washington School of Engineering and Applied Science to do an in-depth

review and analysis of the status and requirements of porous metal

implants. Additional collaborative efforts are in progress with the

FDA, VA, NIH, and Tulane University to plan an Implant Retrieval Symposium

for the Spring of 1980. There is considerable interest in the work of

this project from the community at large and more than twenty presentations

were made this past year to visiting students and groups.

Materials Preparation

D. P. Fickle and F. S. Biancaniello

This laboratory is equipped with a wide variety of melting, fabricating, and processing equipment and carries out numerous activities in

support of the research program needs for special alloys, reference

materials, and research specimens. A principal activity this year has

been the development of an electron beam system for melting, surface

layers under controlled conditions of input power, scanning speed, and

melt depth. Rapidly solidified surface layers (coatings) result from

this technique and have been made on several ferrous alloys to study

their wear properties. A summary of the past year's activities supporting

the Division research program follows.

288
Prepared alloys and specimens for positron annihilation studies to

detect defects: nickel foils, Ti-Al alloys, annealed Ti foils,

nickel foils rolled and annealed in high vacuum, nickel foils

rolled and annealed in hydrogen, Pt95 Cu 5 alloy, rolled and annealed,

nickel foils annealed in hydrogen atmosphere with controlled

cooling rate.

Prepared Cu3 Sn and Cu6 Sn 5 alloys for corrosion studies on dental

alloys.

The following alloys were prepared for use in superconductive

devices for temperature fixed points: directionally solidified

boules of Auln2 and zone refined AuA 1 2 ; Rhodium 99.5 Iron 0.5

alloy, hot rolled for low-temperature resistance thermometers.

Prepared nitrogen free alloys, Ni 3 Al 0<9Ti 0>1 , Ni 3Al 0#5Ti 0>5 , Ni 3 Al 0 . 7 Ti 0 .3 by vacuum electron beam’melting for EXAFS studies.

Prepared Pd and Pd 77 Cu 6 Si 17 alloys for metallic glass solidification studies. Conducted directional solidification and rapid

solidification experiments utilizing this material.

Rolled Pb shielding and gold foil for use in synchrotron x-ray

studies.

Pb-Sn alloys were prepared for Solute Convection Induced Macrosegregation studies in Off-Eutectic Alloys.

An electron beam welding apparatus was acquired and modified to

prepare raster scanned and melted surfaces on steels for wear

studies. A table designed for x-y rectal inear motion was modified

and automated so that rastered surfaces could be generated easily.

A rotating table was designed and constructed to generate high

speed scans at speeds up to 60 cm/sec.

Annealing studies were carried out on two composite materials.

A series of binary Ti-Al alloys were prepared: 94Ti 6A1 , 92Ti 8A1

,

88Ti 12A1, Ti A1 , Ti 2 A1 and Ti 3 A1 (intermetal 1 ic compound ratios).

These include as-cast and heat treated alloys for NMR studies.

Specimens for metal! ographic examination were prepared as well.

A set of Ti-Al specimens were prepared for magnetic susceptibility

studies. The compositions were; 94Ti 6A1 , 92Ti 8A1 , 90Ti 10A1,

88Ti 12A1 , 85Ti 15A1, 80Ti 20A1 and 70Ti 30A1 . These alloys were

heat treated at temperatures of 600 °C, 700 °C, 800 °C, 900 °C,

1000 °C, and 1100 °C.

Pure Ti and Ti 3 A1 compositions will be prepared and heat treated

at selected temperatures to study high temperature phases.

Prepared FcCrNi standard material for microhomogeneity applications.

Prepared Cu and CuZn alloy specimens for studies of diffusion

induced grain boundary migration.

Numerous heat treatments carried out on steel wear specimens.

289
METALLURGICAL CHEMISTRY FOR DURABILITY

The stability of alloy phases is the central theme of this task's

activities. This theme is developed in data, theory, and experiment.

Phase diagram data is a direct objective of part of the task's research

and services. A joint effort mandated by agreement between the Directors

of the National Bureau of Standards and the American Society for Metals

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. Dr. Joanne L. Murray, -a NRC-NBS Postdoctoral Fellow with us, has now been appointed

Chief Analyst of the Alloy Data Center, and will devote special attention

to new methods of on-line graphic display of phase diagram data in collaboration with the Applied Mathematics Division of NEL. The phase diagram

of the Ti-Al system is being studied experimentally with a number of

different techniques as a part of a new 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. A Symposium on the Theory of Alloy Phase Formation was organized and held at the New

Orleans meeting of the AIME. A method for applying d-electron energy band

parameters to prediction of heats of formation of transition metal

alloys has been developed.

Synchrotron x-ray absorption studies (EXAFS) are being carried out

at the Stanford Synchrotron Radiation Laboratory. 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 described elsewhere, focusing

on the understanding of both stable and metastable phases produced by

processing, and devising methods for nondestructive^ detecting them by

hardness, eddy current, and positron annihilation measurements. New

work on the latter completed this year is described under Task, "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 chairmanships

of the Committee on Alloy Phases of the Metallurgical Society of AIME

and ASTM Committee D42 on Surface Analysis.

290
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 chosen on the basis of mechanical

properties, ease of processing, cost, and energy use as well as in

providing substitute alloys and composites. Our work is described in

more detail in the following two sections: Alloy Phase Stability and

Alloys for Fuel Cells and Catalysis.

Technical Activity

Alloy Phase Stability

L. H. Bennett, J. R. Cuthill, J. L. Murray, and L. J. Swartzendruber

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, stressing semi -empirical methods and the

identification of those physical parameters most vital to successful

phase stability predictive schemes.

The Alloy Data Center has established a collaborative alloy phase

diagram critical evaluation program with the ASM. Formalized last year,

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, during the current year, significant improvements

have been made in the METADEX system. More thorough scanning of literature

sources and more extensive indexing have been introduced, and a contract

let for 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. A Bulletin of

Alloy Phase Diagrams will be published; the first number is in preparation

and is expected to be available early next year. Considerable progress

has been made in developing software for on-line graphic display of phase

diagram data through application of spline fitting techniques to published

phase diagram data. Graphics software incorporating phase diagram

prediction techniques and thermodynamic data are also under development.

This graphics work is being carried out in collaboration with the Applied

Mathematics Division of the National Engineering Laboratory. A research

associate supported by ASM has spent a second 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 actually be carried out throughout the world at

institutions recommended by the International Council. Priorities will

291
determine which important classes of systems are evaluated first. At

NBS, we are concentrating on certain systems which can act as models in

that they embody many of the practical experimental and theoretical

difficulties universally encountered, with the objective of establishing

criteria for critical phase diagram evaluation ("standards of evaluation").

We have chosen for immediate evaluation work the Ti-Al system. It

is an ideal system for establishing criteria for critical evaluation.

Many conflicting reports of the Ti-Al phase diagram have appeared in the

literature. A number of experimental difficulties contribute to this

situation. Contamination easily occurs in long anneals: oxygen cannot

be removed, A1 may make hydrogen removal difficult, and surface hydrides

make optical microscopy very difficult. Short anneals lead to non- equilibrium situations. Another difficulty (pointed out by John Cahn) is

that not all phase transitions need be first order. The Landau rules

permit the transformation of a to a DO^ structure to be second order,

for example. Thus, previous investigators may have been misled by

assuming that two phase regions must occur between these phases. The

Ti-Al system also possesses other special theoretical interest; alloying

of an early transition metal (i.e. , a metal with only bonding d-states)

with a nearly free electron metal poses a unique theoretical challenge.

In addition, Ti alloys have important present and potential practical

advantages. Their high corrosion resistance makes them attractive for

marine and chemical processing applications and their high strength to

weight ratio makes them valuable in aviation and space technology. With

better understanding of its phase diagrams, and other basic data, it may

be possible to reduce titanium processing costs so that titanium alloys

could substitute for some stainless steels, as a means of reducing the

U.S. dependence on imported chromium.

We are carrying out new, more carefully controlled experimental work

on Ti-Al, both to clarify the phase diagram of this important system and

to serve as a guide to selection of critical evaluation methods. In

addition, the use of ternary and higher Ti-Al -X systems, of great interest

to the Navy, has been restricted by processing problems and long-term

embrittlement. At the root of these durability and processing problems

is incomplete understanding of the phase stability of these systems. We

are investigating the binary and higher order systems (the latter with

partial support from the Navy) with many of the conventional techniques

for determination of phase diagrams, for example, scanning electron

microscopy, electron microprobe, x-ray diffraction, hardness measurements,

and specialized techniques such as NMR and magnetic susceptibility where

appropriate. A high temperature metal! ographic microscope is being

installed; this instrument is capable of operation in ultrahigh vacuum

or in inert gas atmospheres. Vapor pressure studies by the isopiestic

technique will soon be initiated.

Experiments are underway on several other problems of fundamental

significance to phase stability. The EXAFS technique is being used to

study metastable glassy phases in Ni rich Ni-P alloys on which we have
previously published NMR results, and to study model alloy components of

the complex Ni-based superalloys such as the phase Ni ^A1 i

_

x

Ti x* The

latter work is being undertaken to obtain data on elemental distribution

among the phases present in the superalloys, information necessary to

make predictive schemes such as PHACOMP more reliable. The Mossbauer

effect is a technique which can often both quantitatively measure the

presence of an alloy phase and determine various properties of that

phase. We have used this technique to (1) characterize the magnetic,

electronic, and defect structure of a new phase of potassium ferrite of

possible interest in high temperature applications, and (2) to study the

magnetic properties and identify and quantitatively measure the phase

composition of a type of high strength steel fiber known as "Schladitz

whiskers." The work (1) was performed in cooperation with the Ceramics,

Glass, and Solid State Science Division and with a visiting scientist

from the U.S.S.R. , and (2) with the Chemical Stability and Corrosion

Division. Papers have been submitted for publication describing these

two experiments. Studies are being conducted to determine the applicability

of positron annihilation as an adjunct technique in phase diagram determinations. Emphasis will be placed on Ti-Al alloys and on obtaining

details concerning hydrogen-metal interactions in this alloy system. We

have exploited the sensitivity of positron annihilation radiation to

correlate positron Doppler-broadening with hardness measurements on cold

rolled high purity and commercial grade Ti as a function of annealing

temperature. The positron annihilation measurements revealed defect

changes which occurred at temperatures well below the recrystallization

temperature and which were not detected by hardness measurements. A

paper describing this work is in press.

An invited talk was presented at a recent CALPHAD Meeting in Stockholm,

on the application of predictive methods to, and critical evaluation of

experimental data on, the Ti-Al system. Figure 1 shows the result of one

such predictive method.

A critical survey of various phase diagram determination methods is

being carried out simultaneously with the experimental work. An essential

part of this work is a weekly informal study session on alloy phase

stability. Current emphasis is on the experimental and predictive aspects

of Ti-Al phase diagram determinations.

The major thrust of our theoretical studies continues to be analysis

of the physical parameters important to empirical, thermodynamic, and ab

initio schemes for the prediction of alloy phase and structural stability

In collaboration with R. E. Watson, a paper has been prepared and

submitted for publication describing a method for applying d-electron

energy band parameters to prediction of the heat of formation of transition

metal alloys. A Symposium on the Theory of Alloy Formation was organized

and held at the New Orleans meeting of the AIME.

Dr. Joanne L. Murray, an NRC-NBS Postdoctoral Fellow with us, has

now been appointed Chief Analyst of the Alloy Data Center, and will

devote special attention to the development of on-line graphic display of

phase diagram data, as well as participating actively in our program of

293
theoretical phase diagram predictive schemes. Prof. T. B. Massalski

will be joining us in the fall as a consultant and next year for an extended visit. He will serve as chairman of the International Council's

Panel on binary alloys and will participate actively in both our Ti-Al

experimental program and in our theoretical work on predictive techniques,

particularly in thermodynamics.

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 representatives on the Joint ASTM-SAE Committee on the

Unified Numbering System in Metals and Alloys.

We continue to prepare the circular "Comments" for the Committee on Alloy Phases of the AIME.

Alloys for Catalysis and Fuel Cells

A. J. McAlister and J. R. Cuthill

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, DoD

and EPRI are sponsoring installation of a 4.8 megawatt, naptha fed pilot

assembly in lower Manhattan.

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, Wo. 5 Tio. 5 C, and WP, and strong activity in the ternary

M0] W C (1-x =*0.7, *0.8) which is isostructural with the known strong,

CO poison-resistant fuel electrocatalyst WC.

In the past year we have completed comparative studies of the Mo rich

ternary with WC, and showed it to be equally active and corrosion resistant

for anodic oxidation of H2 , to catalyze the H2 reaction by the same mechanism as WC (see Figure 2), and to be equally tolerant of CO in the

fuel feed. We have also demonstrated that proton discharge is rate

294
limiting on these carbides, in contrast to Pt where chemi sorptive desorption is the slow step. These data were presented in an invited talk at

the National Fuel Cell Seminar in June, and a paper describing these

results has been submitted for publication.

Intrinsic to all problems in heterogeneous catalysis are questions of

surface alloy phase stability. Factors which are important to such

stability include reduced coordination at the surface, surface curvature

and the effects of surface tension, particle-substrate interactions, the

effects of extremely small particle size, and surface reconstruction in

the presence of electrolyte and applied potential.

Several intriguing and difficult experiments aimed at more thorough

understanding of H2 oxidation on non-noble fuel electrocatalysts are

underway. Studies of H2 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.)

Two lines of research aimed ultimately at understanding the geometry of

the active sites on the carbides are being undertaken. Both Raman and

EXAFS studies are capable of yielding microscopic information on catalyst

surfaces i_n situ . A Raman cell has been completed and tested for electrochemical and optical performance. Measurements on carbides will soon

begin. A thin wall EXAFS cell, for fluorescent EXAFS studies of very

small carbide particles i_n situ is being designed.

Other areas of current research include the efficiency of the carbides

as Pt supports (synergistic improvement of Pt's CO tolerance may occur,

and Pt may be more efficiently distributed on the carbides). Equipment

for preparing carbide supported Pt by precipitation and reduction of Pt

salts has been assembled, and the first samples prepared. In addition,

we have observed several refractory hard metals to remain passivated at

potentials well beyond the 0 2 -reduction potential, and will test them for

performance as non-corroding Pt cathode catalyst supports.

J. R. Cuthill is chairman of ASTM Committee E42 on Surface Analysis.

During the current year, two standards have been sent to press and the

Proceedings of a Symposium on Ion Sputtering has been published. Two

symposia are arranged for the coming year, on Interfacial Analysis and

on Quantitative Surface Analysis. A. J. McAlister is a member of E42

and of ASTM Committee D32 on Catalysis as well.

295
TEMPERATURE

(

Fig. 1. The Engel -Brewer correlation is one of several

empirical methods of predicting alloy phase stability.

All theoretical models are most difficult to interpret

or apply to transition - nontransition metal alloys such

as Ti-Al

.

296
c

©o©

oo

(Ac

o

H-

*

i 2.5

0,0 WC - NBS

a, A WC - Literature

+ ,x Moi-x

W

X C ~NBS

A

i i i , i 3.0

10 3/ T

Fig. 2. Transfer coefficient, a, for various prepared

carbide samples. In contrast to i , a is independent

of preparative method. 0

297
Other Division Activities

Sponsored Conferences

Detection, Diagnosis, and Prognosis - System Applications

Mechanical Failures Prevention Group, 28th meeting, San Antonio,

Texas

November 28-30, 1978.

Symposium on the Theory of Alloy Formation

Annual Meeting of the AIME, New Orleans, Louisiana

February 18-22, 1979.

Advanced Composites: Design and Application

Mechanical Failures Prevention Group, 29th meeting, Gaithersburg,

Maryland

May 23-25, 1979.

Invited Talks

Wear Debris: Formation Mechanisms and Analysis

AIME/ASM Conference, St. Louis, Missouri

A. W. Ruff

October 16, 1978.

Solid Particle Erosion: Introductory Remarks

NACE Conference on Corrosion/Erosion; Berkeley, California

A. W. Ruff

January 25, 1979.

Solid Particle Erosion of Metals and Ceramics

Golden Gate Metals and Welding Conference, San Francisco, California

A. W. Ruff

February 1, 1979.

Metallurgical Studies of Wear and Erosion

Martin Marietta Research Laboratories, Baltimore, Maryland

A. W. Ruff

April 24, 1979.

Microscopic Aspects of Wear in Metals

Navy Tribology Meeting, Annapolis, Maryland

A. W. Ruff

May 22, 1979.

Measurements and Standards for Dry Wear

American Chemical Society Conference on Corrosion and Wear,

Washington, D.C.

A. W. Ruff

June 5, 1979.

298
Hume-Rothery 1 s "Old Metallurgist" Revisited: A Discussion of

Digital Processing of Transient Signals with Special Reference to

Acoustic Emission

Second International Conference on Acoustic Emission and Materials

Evaluation sponsored by Inst, of Acoustics and British AE Working

Group, London, England

R. B. Clough

April 1979.

Digital Processing of Transient Signals with Special Reference to

Acoustic Emission

Atomic Energy Research Establishment, Harwell, England

R. B. Clough

April 1979.

The Use of Metals as Surgical Implants

Biomaterials Seminar, Johns Hopkins University, Baltimore, Maryland

A. C. Fraker

March 1979.

Microstructural Changes in Copper Due to Abrasive, Dry and Lubricated

Wear

International Conference on Wear of Materials - 1979, Dearborn, Michigan

L. K. Ives

April 1979.

On Determining Stress in Bolts U1 trasonical ly

ARPA/AFML Review of Progress in Quantitative NDE, Scripps Institution

of Oceanography, La Jolla, California

D. E. MacDonald

July 1979.

On Determining Stress and Strain and Texture Using Ultrasonic

Velocity Measurements

1979 International Ultrasonics Symposium, IEEE, New Orleans, Louisiana

D. E. MacDonald

September 1979.

An Atomic Model of Strain Induced Martensitic Transformation

Inti. Conf. on Martensitic Transformations

D. E. MacDonald

June 1979.

Female Chemistry (Non-Chauvi nistic)

Chemical Society of Washington, George Mason University, Washington,

D.C.

G. J. Mattamal

April 1979.

EXAFS: A Local Structure Probe

University of Maryland (Baltimore County)

A. J. McAlister

March 1979.

299
H 2 Oxidation on Mo-W Carbide Alloys in Acid Electrolyte

National Fuel Cell Seminar, Bethesda, Maryland

A. J. McAlister, M. I. Cohen and L. H. Bennett

June 1979.

Nuclear Hyperfine Positron Annihilation Methods for Measurements of

Longitudinal Force in Rails

Department of Energy, Washington, D.C.

L. H. Bennett

February 26, 1979.

Current Research in Acoustic Emission at NBS

European Acoustic Emission Working Group, Risley, England

J. A. Simmons

October 1978

Elastodynamic Green's Tensor for an Isotropic Plate

Theoretical Physics Division, United Kingdom Atomic Energy Research

Establishment, Harwell, England

J. A. Simmons

October 1978.

Theory and Experiment of Titanium Alloys

CALPHAD Conference, Stockholm Sweden

J. L. Murray

May 1979.

Alloy Phase Stability

The Physics Club of Richmond, Richmond, Virginia

L. H. Bennett

April 1979.

Parameters in Semi -Empirical Theories of Alloy Phase Formation

Annual AIME/TMS Meeting, New Orleans, Louisiana

L. H. Bennett

February 1979.

Costs of Corrosion

1978 Greater Boston Section Corrosion Control Meeting, Boston,

Massachusetts

L. H. Bennett

October 1978.

The ASM/NBS Alloy Phase Diagram Program

General Electric Corp. , Schenectady, New York

L. H. Bennett

November 1978.

Materials Stability at High Temperatures, Reliability of Materials

for Solar Energy

Solar Energy Research Institute Materials Workshop, Denver, Colorado

J. R. Manning

December 1978.

300
Defect Gradient Effects on Diffusion in Irradiated Alloys

Oak Ridge National Laboratory, Oak Ridge, Tennessee

J. R. Manning

August 1979.

Morphological Stability

Defense Advanced Research Projects Agency, La Jolla, California

S. R. Coriel 1 July 1979.

Surface Tension Measurements of Liquid Gallium

NASA Headquarters, Washington, D.C.

S. C. Hardy

June 1979.

Nuclear Hyperfine and Positron Annihilation Methods for Measurements

of Internal Stress

Department of Transportation, Washington, D.C., Conference on Methods for Measuring Internal Stress in Parts

L. H. Bennett and L. J. Swartzendruber

February 1979.

Magnetic Leakage and Force Fields for Artificial Defects in Magnetic

Particle Test Rings

12th Symposium on Nondestructive Testing, San Antonio, Texas

L. J. Swartzendruber

April 1979.

Publications and Patents

Thickness of Gold Coating Measured with a Calibrated SEM

D. B. Ballard and F. Ogburn

to be published in Plating and Surface Finishing a Journal of the

American Electroplated s Society (1979).

SEM Studies of Dental Casting Alloy Corrosion Behavior

H. Weber and A. C. Fraker

Proc. of the Electron Microscopy Society of America Meeting (1979)

to be published.

An Atomic Model of Strain Induced Martensitic Transformation

D. E. MacDonald

Proc. of Inti. Conf. on Martensitic Transformations (1979).

Numerical Physical Property Data for Metal Hydrides Utilized for

Hydrogen Storage

L. J. Swartzendruber, G. C. Carter, D. J. Kahan, M. E. Read and

J. R. Manning

Proceedings of the 2nd World Hydrogen Energy Conference, Zurich,

Switzerland; August 21-24, 1978; Hydrogen Energy System, Volume 4

(Pergamon Press) pp. 1973-2011.

301
Lateral Solute Segregation During Unidirectional Solidification of

a Binary Alloy with a Curved Solid-Liquid Interface

S. R. Coriel 1 and R. F. Sekerka

Journal of Crystal Growth, 45, pp. 479-482 (1979).

The Motion of Bubbles in a Vertical Temperature Gradient

S. C. Hardy

Journal of Colloid and Interface Science, 69, pp. 157-162 (1979).

X-ray Magnifier

W. J. Boettinger, H. E. Burdette and M. Kuriyama

Review of Scientific Instruments, 50, pp. 26-30 (1979).

An Introduction to the Principles of X-ray Topography . M. Kuriyama

0Y0 BUTSURI (Applied Physics) (in Japanese) 4£, 143-149 (1979).

Application of X-ray Topography to Metallurgy

M. Kuriyama

Bulletin of Japan Institute of Metals, J8, pp. 335-341 (1979).

Influence of the Space Environment on Some Materials Processing

Phenomena

S. R. Coriel 1 and R. F. Sekerka

Proceeding of Third European Symposium on Material Sciences in

Space (in press).

Polarization Effects in X-ray Scattering and Diffraction

G. G. Cohen and M. Kuriyama

Phys. Rev. B (to be published).

X-ray Residual Stress Evaluation by an Energy Dispersive System

M. Kuriyama, W. J. Boettinger and H. E. Burdette

Proceedings of Symposium on Accuracy in Powder Diffraction (NBS)

(in press) 1979.

Crystal Subgrain Misorientations observed by X-r’ay Topography in

Reflection

R. W. Armstrong, W. J. Boettinger and M. Kuriyama

(to be published in Journal of Applied Crystallography).

Real-Time Radiographic System Performance Standards

M. Kuriyama, W. J. Boettinger and H. E. Burdette

ASNT Proceedings Fall Meeting (St. Louis) 1979 (in press).

Energy Dispersive XRF Composition Profiling using Crystal Collimated

Incident Radiation

W. J. Boettinger, H. E. Burdette and M. Kuriyama

Advances in X-ray Analysis, Vol . 23 (in press).

X-ray Polarization Rotation

M. Kuriyama and G. G. Cohen

Physical Review B (in press).

302
Experiments in Acoustic Emission Waveform Analysis for Characterization

of AE Sources, Sensors, and Structures

N. N. Hsu and S. C. Hardy

Elastic Waves and Nondestructive Testing of Materials, AMD-Vol. 29

(1978).

An Approach to Acoustic Emission Signal Analysis - Theory and

Experiment

N. N. Hsu, J. A. Simmons and S. C. Hardy

Materials Evaluation (1978).

Transport Properties in Fluids

J. R. Manning

Applications of Space Flight in Materials Science and Technology,

NBS Special Publication 520, pp. 102-104 (1978).

Heats of Formation of Transition Metal Alloys

R. E. Watson and L. H. Bennett

Phys. Rev. Letters.

What's Special About Transition Metals in Alloy Phase Formation

R. E. Watson and L. H. Bennett

Proc. of Annual TMS/AIME Meeting, February, 1979.

Magnetic Leakage and Force Fields for Artificial Defects in Magnetic

Particle Test Rings

L. J. Swartzendruber

Proc. of Symposium on Nondestructive Evaluation

San Antonio, Texas, 1979.

Positron Annihilation Study of Defects in Titanium

R. C. Reno, L. J. Swartzendruber and L. H. Bennett

NDT International.

Magnetic Properties and Hyperfine Interactions in p' 1Phase of

Potassium Ferrite

V. P. Romanov, G. A. Candela, R. S. Roth and L. J. Swartzendruber

J. of Applied Physics.

The American Society for Metals and’ NBS Alloy Data Center Joint

Compilation Program for Alloy Phase Diagrams

G. C. Carter, L. H. Bennett, D. J. Kahan, A. G. Gray, H. D. Chafe

and E. Langer

Proc. of the 6th International CODATA Conference, 1979, p. 235.

Nuclear Hyperfine and Positron Annihilation Methods for Measurements

Longitudinal Force in Rails

L. H. Bennett and L. J. Swartzendruber

Proc. of Conf. on Methods for Measurements of Internal Stress, in

press.

Crystal Structure of a New Compound Li 5 B 4

F. E. Wang, M. A. Mitchel , R. A. Sutula, J. R. Holden and L. H. Bennett

J. of the Less Common Metals 61_, (1978) p. 237.

303
A Mull i ken Electronegativity Scale and the Structural Stability of

Simple Compounds

R. E. Watson and L. H. Bennett

J. Phys. Chem. Solids 39, (1978) p. 1235.

Electron Factors in the Occurrence of Sigma and Structurally Related

Transition Metal Alloy Phases

R. E. Watson and L. H. Bennett

Scripta Metal lurgica 1_2, 1978, p. 1165.

Transition Metals: d-Band Hybridization Electronegativities and

Structural Stability of Intermetallic Compounds

R. E. Watson and L. H. Bennett

Phys. Rev. 18, 12 (1978) p. 6439.

Nuclear Magnetic Resonance in LaNi 5 M. Rubinstein, L. J. Swartzendruber and L. H. Bennett

J. Appl . Phys. 50, (1979) p. 2045.

Stacking Solutions in w-phase Systems and Quasi elastic Scattering

B. Horovitz, J. L. Murray and J. A. Krumhansl

Phys. Rev. B J8, 7, 1978.

Debris Analysis of Erosive and Abrasive Wear

A. W. Ruff

Proceedings of the International Conference on Fundamentals of

Tribology, MIT, 1979.

A Mechanism for Metalloid Strengthening of Udimet-700

S. Polvani, A. W. Ruff and P. R. Strutt

in press.

Erosion by Solid Particle Impact

A. W. Ruff and S. M. Wiederhorn

in Erosion , ed. C. M. Preece, Academic Press, New York (1979).

Electron Microscopy Study of Erosion Damage in Copper

L. K. Ives and A. W. Ruff

Proceedings of the ASTM Symposium on Erosion, Vail, Colorado, 1979.

Measurements and Standards for Dry Wear

A. W. Ruff

Proc. Conference on Corrosion and Wear (Am. Chem. Soc. , 1979).

Solid Particle Erosion: Introductory Remarks

A. W. Ruff

Proc. of NACE Conference on Erosion/Corrosion, Berkeley, California,

1979.

Economic Effects of Metallic Corrosion in the U.S.

L. H. Bennett and A. W. Ruff, et al

Proceedings of NACE Corrosion .Conference, Atlanta, Georgia, 1979.

304
Seminars for Staff and Guests

Dr. P. J. Blau

Microstructure-Based Models for the Sliding Wear and Friction of

Single-Phase Metals

March 6, 1979.

Dr. Charles Schwarz

Used Oil Analytical Techniques and Test Methods

May 21, 1979.

Prof. M. J. Furey

Chemical Aspects of Boundary Lubrication

May 31, 1979.

Dr. S. Weisman

Forged High Strength Vitalii urn Alloy

February 9, 1979.

Dr. E. Smethurst

Fretting and Corrosion Fatigue Behavior of Implant Alloys

June 13, 1979.

Dr. H. Wadley

Acoustic Emission During the Deformation and Fracture of Metals

August 1979.

Dr. Donald Polk

Thermal and Mechanical Behavior of Zr-Cu Metallic Glasses

May 18, 1979.

Dr. D. B. Oulton

Non-Linear Theory of Interface Stability During Solidification

July 1979.

Dr. G. Purdy

Diffusion-Enhanced Grain Boundary Migration

May 1979.

Prof. Dr. B. Predel

Thermodynamic Investigations of Liquid Alloys

September 1979.

Prof. J. B. Vander Sande

Applications of Scanning Transmission Electron Microscopy to Problems

in Materials Science

December 8, 1978.

Dr. M. J. Loretto

Electron Microscopy and Stacking Faults

June 1979.

305
Dr. R. Mehrabian

Rapid Solidification Processing

December 13, 1978.

Dr. K. T. Hartwig

Materials Processing Methods for a Large Superconducting Cable to

be Used for Energy Storage

December 21, 1978.

Dr. L. Schlapbach

Structure, Magnetic and Surface Properties of LaNi 5 and FeTi Hydrides

December 27, 1978.

Dr. J. C. Williams

A Review of the Deformation Behavior of crTitanium

April 26, 1979.

Dr. R. J. Schaefer

Surface Coating Application by High Power Lasers

June 7, 1979.

Dr. S. J. Rothman

Tracer Diffusion in Austenitic Fe-Cr-Ni Alloys

May 10, 1979.

Dr. E. M. Breinan

Advances in Rapid Solidification Laser Processing

May 1979.

Dr. S. A. Brown and K. Merritt

Implants, Corrosion and Metal Allergy: Studies in Animals and Man

April 26, 1979.

Dr. A. D. Pelton, Dr. C. W. Bale and Dr. W. T. Thompson

The F*A*C*T* (Facility for the Analysis of Chemical Thermodynamics)

Computer System and its Application in the Compilation and Evaluation

of Phase Diagrams and Thermodynamic Data of Solutions

June 29, 1979.

Dr. I. Hansson

Research at the Laboratory of Applied Physics 1 on Ultrasonic

Cavitation Erosion, Plasticity, and Fatigue

July 2, 1979.

Dr. J. Hamilton

Surface Segregation in Alloys: Experiment and Theory

July 25, 1979.

306
Special Reports

Materials for Fuel Cells

L. H. Bennett, C. K. Chiang, M. I. Cohen, A. L. Dragoo, A. D. Franklin and A. J. McAlister

NBSIR (in press).

NBS: Properties of Electronic Materials

J. R. Manning

NBSIR 79-1767.

Technical and Professional Committee Participation and Leadership

ASTM E9, Task Group 3, Residual Stress Effects in Fatigue

J. A. Simmons.

Society for Experimental Stress Analysis, Technical Committee on Residual Stress

J. A. Simmons.

ASTM E28, Mechanical Testing; Residual Stress Standards

J. A. Simmons.

American Society for Mechanical Engineers, Ad Hoc Working Group on Acoustic Emission

J. A. Simmons.

ASTM/ASME, Joint Task Group on Acoustic Emission System Calibration

J. A. Simmons.

ASTM E7, Nondestructive Testing; Subcommittee on Acoustic Emission

J. A. Simmons

Vice-Chairman.

ASTM F4, Surgical Implants; Resources; Test Methods

A. C. Fraker.

ASTM G2.91, Subcommittee on Terminology and Definitions

L. K. Ives

Chairman.

ASTM G2, Subcommittee on Erosion by Solid Particle Impact, Wear,

Erosion and Wear

L. K. Ives.

International Council for the ASM/NBS Program for Alloy Phase

Diagrams

L. H. Bennett.

SAE-ASTM Unified Numbering System for Metals and Alloys

L. H. Bennett.

Metallurgical Society, AIME, Committee on Alloy Phases

L. H. Bennett

Chai rman.

307
ASTM E7, Nondestructive Testing

L. H. Bennett.

International Council for the ASM/NBS Program for Alloy Phase

Diagrams

J. R. Cuthill.

ASM Handbook Committee on Definitions

J. R. Cuthill.

SAE-ASTM Unified Numbering System

J. R. Cuthill

Alternate Representative.

ASTM E42, Surface Analysis

J. R. Cuthill

Chai rman.

ASTM E42, Surface Analysis

A. J. McAlister.

ASTM D32, Catalysts

A. J. McAlister.

ASTM B5, Copper and Copper Alloys; Methods of Test

L. J. Swartzendruber.

ASTM E4, Metallography

L. J. Swartzendruber.

ASTM E7, Nondestructive Testing

L. J. Swartzendruber.

Maryland Institute of Metals

W. J. Boettinger

President.

Solidification Committee of the Metallurgical Society of AIME

W. J. Boettinger

Chai rman.

ASTM B7, Light Metals and Alloys; Aluminum Alloy Ingots and Castings

W. J. Boettinger.

Solidification Committee of the Metallurgical Society of AIME

S. R. Coriel 1.

Advisory Board for International Journal Diffusion and Defect Data

D. B. Butrymowicz

Board Member.

National Materials Advisory Board, Committee on Aluminum Powder

A1 1 oys

J. R. Manning.

308
Mass Transport Activity of American Society for Metals

J. R. Manning.

Process Modeling Activity of American Society for Metals

J. R. Manning.

Materials Processing in Space Panel of the NASA Applications Steering

Committee, Supporting Research and Technology Subcommittee

J. R. Manning.

Executive Committee of Washington Chapter of American Society for

Metals

S. R. Coriell.

Editorial Board of International Journal of Crystal Growth

R. L. Parker

Deputy Principal Editor.

US-USSR Joint Committee on Electrometal lurgy

R. L. Parker.

Visiting Committee for Metallurgy and Materials Science Department

of Carnegi e-Mellon University

R. L. Parker.

International Council of Scientific Unions, Committee on Space

Research (COSPAR)

R. L. Parker.

Council of International Organization of Crystal Growth

R. L. Parker.

Executive Committee of American Association for Crystal Growth

R. L. Parker.

Electronic Materials Committee of the Metallurgical Society of

AIME

R. L. Parker.

ASTM A1 , Steel, Stainless Steel-, Related Alloys; Castings

R. L. Parker.

Florence Review Committee, Review of Scanning Electron Microscopes

D. B. Ballard

Chai rman.

ASTM E4, Metallography; Electron Metallography; Scanning Electron

Microscopy

D. B. Ballard.

ASTM G2, Erosion and Wear

A. W. Ruff

Vice-Chairman.

309
ASTM G2, Erosion and Wear

A. W. Ruff

Editorial, Chairman.

ASTM F4, Surgical Implants, Resources, Metallurgical Materials

A. W. Ruff.

ASM, Metal Progress

A. W. Ruff

Editorial Committee.

ASM, Division of Materials Testing and QC

A. W. Ruff

Councilor.

ASTM E28.13, Measurement Methods for Residual Stress

D. E. MacDonald.

ASTM B6, Committee on Die-Cast Metals and Alloys

R. Mehrabian

Chairman.

Process Modeling Activity of American Society of Metals

R. Mehrabian.

US-USSR Joint Subcommittee on Electro-Slag Remelting

R. Mehrabian.

Visiting Committee for the Department of Metallurgy and Materials

Science, Carnegi e-Mellon University

R. Mehrabian.

Solidification Committee of the Metallurgical Society of AIME

R. Mehrabian.

Composite Committee of ASM- AIME

R. Mehrabian.

Second International Conference on Rapid Solidification Processing

R. Mehrabian

Chai rman.

National Materials Advisory Board Committee on Amorphous and Metastable

Materials

R. Mehrabian.

National Materials Advisory Board Committee on Superalloy Powder

A1 1 oys

R. Mehrabian.

Adjunct Professor of Metallurgy and Mining Engineering, University

of Illinois at Urbana, Champaign, Illinois

R. Mehrabian.

, 310
Consulting and Advisory Data Centers

Alloy Data Center

L. H. Bennett, J. L. Murray, J. R. Cuthill and D.

Diffusion in Metals Data Center

M. E. Read and D. B. Butrymowicz.

J. Kahan.

311
CERAMICS, GLASS, AND SOLID STATE SCIENCE DIVISION

312
’

'
CERAMICS, GLASS AND SOLID STATE SCIENCE DIVISION

Hans P. R. Frederikse, Chief

J. Bartlett, Administrative Aid

M. A. Clevinger, Administrative Aid

B. A. Hyde, Adminsitrative Aid

K. R. Morgan, Clerk Stenographer

E. R. Smith, Administrative Aid

The Ceramics, Glass and Solid State Science Division was formed in

April 1978 during the Bureau-wide reorganization implemented at that

time. This Division, with a staff of just over 50 is one of six Divisions

that make up the Center for Materials Science. Its history goes back

several decades: the (somewhat larger) predecessor was called the

Inorganic Materials Division, which received that name in 1964. During

the quarter century before that date the Division was known as the

Mineral Products Division.

The present activities of the Division can best be described in terms

of the Task Structure:

Task 1215-1. Structural Chemistry for Ceramic Processing and Durability

1215-3. Structural Methods for Processing, Manufacturing, and

Durability

1215-4. Properties, Structure, and Standards for Glass and Optical

Materials

and 1215-5. Durability of Ceramics and Glass in Service Environments

Another way of classifying the Division's work would be by disciplines: Solid State Chemistry (1), Solid State Physics (4b), Structure

of Crystals (Crystallography) (3), and Structure of Glass (Vitrous State)

(4a). Because most of the Division's activities are concerned with ceramics, glass, and optical materials, there is much emphasis on high tempera'

ture research.

A lot of the work has to do with materials characterization as a basis for scientific understanding and technological applications.

Characterization logically leads to four activities that relate to major

Bureau programs:

Data Centers - Crystal Data, Phase Diagrams, Materials Performance

for Energy Applications

Standard Reference Materials - Glass Properties, X-ray Standards,

Thermal Expansion

Nondestructive Evaluation - Eddy Current, Light Scattering

Resource Recovery and Recycling - Waste Glass, Fly-ash (incinerators)

314
Characterization also implies special, sophisticated measurement

techniques. Within the Division there are a number of experimental

facilities, some of which are used throughout CMS and NML and are partly

supported by those units. A partial list of these instruments includes

the Raman facility, the diamond anvil pressure cell, the Scanning

Electron Microscope, a number of x-ray diffractometers (among which is a microdiffractometer), DTA and TGA equipment, an apparatus for thin film

deposition and characterization, and instrumentation for measuring the

refractive index n (as well as dn/dT and dn/dP) of optical materials.

During this year two events took place that have thoroughly

affected the operation of the Division. The first was a result of

internal (NBS) reprogramming and the second was caused by a sudden

change in policy of the Department of Energy.

During the summer of 1978, it was decided that the Bureau would

embark on a sizable program in the area of Electronics (VLSI) and that

this activity would be strengthened by a transfer of half a dozen

scientists from the Solid State Materials Group of this Division to the

Center for Electronics and Electrical Engineering. During the first

half of FY 1979 this group was encouraged to educate themselves in the

area of semiconductor physics and to start some experimental work in

this field. The actual reassignment (accompanied by a transfer of a significant part of the Division's base funds) took effect on February 25,

1979. Although the departure of one half of the Solid State Materials

Group constitutes a severe loss, the remaining half guarantees the continuation of solid state physics research which is essential to the Division's

program. This group contains a number of scientists well versed in the

optical and transport properties of materials.

The second event was the sudden cancellation by the Department of

Energy of funds earmarked for the continuation of the six-year old NBS-DoE

program on development of MHD-material s. Although about one- third of this

money was restored in the second half of the fiscal year, the financial

health of the Division required a reduction of force involving five staff

members.

At the end of FY 1979 it appears that the Division has recuperated

rather well from these two shocks.

The Glass Technology Group has initiated a program concerned with

the preparation and properties of glassy films ranging in thickness from

nanometers to micrometers. Scientifically, the emphasis will be on glass

formation in films, especially complex layers produced by coevaporation.

The possible applications are numerous, including coatings for optical

components and solar panels, optical waveguides, film capacitors, displays,

etc. During this fiscal year a thin film facility, consisting of separate

deposition and characterization chambers was designed, procured, and

assembled.

315
The NDE program on eddy currents for flaw detection in metals has

stirred considerable interest of industrial groups and workers in other

government laboratories. Another NDE project concerned with the perfection of optical surfaces has just been started.

High pressure research , carried out with the aid af the Bureau's

diamond anvil pressure cell, is continuously meeting new challenges both

at NBS, and elsewhere. A careful study of CuCl , conducted in cooperation

with scientists at Bell Labs, and Stanford University, has shown that this

material undergoes a number of phase transitions below 110 kbar, but does

not become a superconductor.

Currently, several groups of solids known as

“ modulated structures " are receiving broad attention from solid state chemists. Several compounds

of the scheelite structure [e.g. , (LaTh) Nb0^

+x ] that are being studied

in this Division, appear to be interesting examples of this group.

Cooperation between scientists at NBS, HDL, and at a ceramics

company in Gaithersburg have led to the development of a fl uidicelectrochemical (CSZ) cel 1 which measures both the temperature and the

partial oxygen pressure of gases and vapors at temperatures up to 1700 °C.

A summary of NBS work on refractive i ndexes and related parameters

of some 14 optical material

s

(including several halides, oxides, and

glasses) was published in February of this year. These data are of

prime importance for the design of optical systems, especially for those

set ups that involve high power lasers.

Considerable amounts of time and effort were devoted to the formulation of new pi ans and proposal

s

usually in collaboration with other

individuals or groups in NBS. An example of such an undertaking was the

preparation of an "Initiative on Materials Processing" (later called

"Materials Transformations") between August 1978 and January 1979.

Originally, the initiative was divided in four parts: a) thermal processing, b) thermo-mechanical processing, c) coatings and films, and d)

powders and particles. The Division was involved in all four items, but

only the contribution to part a), which described a program on GlassCeramics, made it to the final draft stage. Apparently, because of

funding limitations imposed on the overall initiative, even this program

is not included in the Bureau's total budget proposal for FY 1981. At

present, attempts are being made to strengthen the "Coatings and Films"

section as a separate Initiative Proposal. Similar plans are being

contemplated for "Powders and Particles." It is obvious that the

Division is very much interested in Ceramic Processing and Glassmaking

and consequently wants to participate in a Processing (or Transformations) initiative.

Several other studies were conducted during the past year:

316
A. Composites (included in FY 81 budget, mainly polymers).

B. Interfaces: the application of High Resolution Electron Microscopy

will be very important. Dr. Roth intends to spend in FY 80 3 months at

the University of Arizona to familiarize himself with this instrument.

C. High intensity x-rays. Members of the crystallography group are

part of the competence building effort in this field, involving use of 2

NBS-NRL experimental stations of the synchrotron radiation facility at

Brookhaven, which is presently being constructed.

D. Mass and Charge Transport. The Division has a considerable stake in

this area in connection with its work on MHD electrodes and fast- ion

conductors, etc. The problems of high temperature ionic and mixed

ionic-electronic conduction, and their relation to crystal structure are

central to the mission of the Division. Recently, discussions have

started between members of this Division and of the Chemical Stability

and Corrosion Division and the Metal Science and Standards Division

aimed at a strengthening of the Center's competence in the area of

Transport Processes.

The following pages describe in detail this year's technical and

scientific achievements under each of the four Tasks.

317
Technical Activity

STRUCTURAL CHEMISTRY FOR CERAMIC PROCESSING AND DURABILITY

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 aluminum-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 which make up the composition of coal slag and of most high volume refractory ceramic materials

(Na2 0, K2 0, CaO, MgO, FeO

x>

A1 2 0 3 , Si

0

2 ) . The second group consists of

materials of interest for electronic ceramics, 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

energy- related disciplines. The list of publications resulting from these

studies during the past year includes three non-archival summary reports

and one large review of materials research. Each of these was preceded

by numerous monthly and/or quarterly reports. In addition, twelve talks

were given. Many visits were also made by Task members between November

1978 and October 1979 to other university, government, and industrial

laboratories concerned with materials research in energy- re 1 ated activities.

318
Phase Equilibria

Calculation of Phase Diagrams

L. P. Cook, R. S. Roth, and D. P. Birnie

In an attempt to treat the complexity of crystal/! i quid interaction and liquid/liquid separation in seven component silicate melts,

recently developed theories of silicate melt structure have been applied

and extended. The model used has been derived from that of Masson and

others, who based their approach upon the principles of polymer chemistry.

The model used is quasichemical in that it deals not with the actual

species involved, but with a quantity which summarizes the essential

properties of these species, in this case the relative numbers of bridging

and nonbridging oxygens in the melt structure. A reasonable amount of

success has been encountered in interpreting the liquidus surface of the

primary phase field of KA1 Si

0

4 in the system K2 0-CaQ-Mg0-FeQ -A1 2 0 3

- Si02 using modified versions of this theory. Similarly, experimental

data on high temperature immiscible liquids coexisting with KAlSi0 4 has

been duplicated surprisingly well using modified versions of the theory

with appropriate assumptions. Such interaction between calculation and

experimentation provides the best hope of obtaining the necessary understanding of important high temperature silicate equilibria in a finite

amount of time.

It is anticipated that programs for the calculation and display of

complex silicate equilibria will be developed in the near future on our

system. Currently available and undergoing evaluation and modification

are programs for the calculation of binary and ternary subsolidus phase

diagrams using limited experimental data, and also for the derivation of

thermodynamic data from phase diagrams. Such programs will find application

in all areas of phase equilibrium research and utilization, but especially

in any future research related to fossil fuel conversion and nuclear

waste disposal. Ultimately, published equilibrium diagrams may be

analyzed and discussed with the aid of such programs.

Preparation of "Phase Diagrams for Ceramists"

L. P. Cook, R. S. Roth, T. Negas, and R. Bird

Editing of the 1300 commentaries and diagrams for the 1980

Supplement is approaching completion. While the number of commentaries

is about 50% larger than in the 1975 Supplement, the individual commentaries

are somewhat shorter, and so it is anticipated that the new Supplement

will be about the same size as preceding editions. As of August 1 the

totals for the various chemical groupings were: metal -oxygen (110);

oxides (388); oxygen-containing radicals (77); halides only (324);

halides with other substances (179); cyanides, sulfides (69); oxycarbides, oxynitrides (10); aqueous systems (112); C0 2 -contai ning systems

(18); and systems with H-C-N-O-S gases (32). It should be noted that

oxycarbides/oxynitrides , C02 -containing systems, and gas-containing

319
systems are new categories. It is anticipated that the oxycarbide/

oxynitride categories will continue to expand with increasing interest

in these relatively new materials, especially the SIALONS. To aid the

ceramist in dealing with the increasingly numerous problems related to

ceramic-gas and ceramic-fluid interaction, a new section containing

relevant gas phase equilibria has been added. It has been convenient to

distinguish a separate section for phase equilibria in systems con- taining C02 -bearing fluids, as these involve primarily high pressure

equilibria.

Use has been made df an "intelligent" terminal with editing

capability to store entries for the 1980 Supplement on magnetic tape,

and sort them according to the "Phase Diagrams for Ceramists" classification

scheme. Using other programs in conjunction with the central computing

facility, a cumulative index is being prepared. Use of sorting routines

has proved indispensable in carrying out the final editing and arrangement of the publication. It is anticipated that the computer will

become used much more extensively in "Phase Diagrams for Ceramists" data

processing.

The aid of two additional contributing editors has been enlisted.

Professor D. Kolar of the Josef Stefan Institute, Ljubljana, Yugoslavia,

is assisting with the Eastern European phase equilibrium studies for

which English translations are difficult to obtain. Dr. J. Coutures,

CNRS, Odeillo, France, is helping with the refractory rare-earth oxide

systems, many of which are being studied in his solar furnace laboratory.

A meeting of U.S. contributing editors, as well as Prof. F. Glasser,

University of Aberdeen, was held at the American Ceramic Society Annual

Meeting (May 1979) in Cincinnati.

Most of the material from the first list of some 700 references

with 1700 phase diagrams for potential inclusion in the 1983 Supplement

has been received from the contributing editors. However, review of

this material and mailing of additional lists has been delayed pending

completion of editing of the 1980 Supplement, anticipated by October 1,

1979.

Crystal Chemistry

Crystal Chemistry of Potential Mixed Conductors and Electrode

Catalysts

T. Negas, R. S. Roth, J. L. Waring, M. C. Austin, and C. L. Skarda

An investigation of the thermochemistry in the YFe03 -Ca2 Fe2 0 5 system was completed. The perovskite, YFe03 , accommodates <0.10 Ca in

Y^Ca^eD^. Although excellent p-type conductors, the perovskite-based

materials are limited by melting at temperatures as low as ~ 1420 °C.

Several nonstoichiometric materials within the Ca-rich portion of the

system were detected but not characterized completely. Results were

reported by R. S. Roth, T. Negas, and C. L. Skarda at the American

Chemical Society Conference, 1979.

320
Varying levels of dopants in Y-j M CrO^ (M = Ca, Mg) and in

YCr-j Mg 0^ were investigated using specimens prepared by thermal

sintering and hot pressing methods. Reduced materials O 10 15 atm, P n )

o+

U2

are hi ghly

+

resi stive and characterized by Cr3 and oxygen vacancies,

Y, Ca Cr3 0~ /0 . After oxidation at elevated temperatures (Pn > 10 6

i ~x X j— X/ c. U2

electrical conduction is of the p-type and stoichiometries conform to

3+ 4+ 2+ Y^Cr^Cr 03 - Under oxidizing conditions, YCr03 incorporates Ca

at least to x = 0.10. However, the material at x = 0.10, when reduced,

disproportionates to a multiphase assemblage. Reoxidation, involving

re-solution of exsol ved phases, result in severe fissuring of dense

ceramics. Correlations were made among electrical data, processing

parameters, bulk and microchemistry, and microstructure. Thermal

diffusivity/expansion data were obtained. Results were reported by

T. Negas, W. R. Hosier and L. Domingues at the International CIMTEC

Conference, Italy, 1979.

In cooperation with HDL and a private company, a ceramic

sensor for simultaneous measurement of P n and T° was developed. The

u 2

device combines a conventional P n sensor (ionic conductor, e.g. , doped

u2

Zr02 ) with a fluidic capillary system that measures temperature directly.

A common working/reference fluid (e.g., air) is utilized. Fabrication is

being performed by a private company to yield prototype sensors which

can be tested/calibrated in the laboratory. Patent applications were

filed at HDL (T. Negas, L. Domingues, T. Drzewieki, R. Phillippi).

Crystal Chemistry, Crystallography and Electrical Conductivity

In Rare-Earth Niobates and Tantalates

R. J. Cava, R. S. Roth, T. Negas, H. S. Parker, and D. B. Minor

Previous oxidation-reduction experiments in this laboratory

indicated that CeNb0 4 and CeTa0 4 could be made to accommodate excess

oxygen by the change of normally present Ce

3_r

to Ce 4. The kinetics of

the oxidation process suggested the possibility of fast oxygen transport.

However, the conductivity in these materials would be difficult to study

due to the limited P n -temperature stability ranges of the oxidized

u2

polymorphs. We, therefore, decided to study the lanthanum analogues,

LaNb0 4 and LaTa04 , doped with Th02 and W0 3. The oxygen_excess phases

which result are not P n sensitive, at least between 10 5 atm and

u2

ambient. In addition, in these materials in which mixed valence atoms

are not present, hopping-type electronic conductivity should not occur.

321
Conductivities were measured on polycrystalline ceramic pellets

by complex impedance techniques. Measurements at frequencies between 60 Hz

and 13 MHz were made on the network analyzer in Dr. A. D. Franklin's

laboratory in the Chemical Stability and Corrosion Division. An apparatus

was constructed which allowed conductivities to be measured up to 1000 °C,

in air or mixed gases. Studies were generally conducted at P n > u2

10 6 atm to preclude the possibility of reduction of niobium. The

apparatus is also capable of measuring the Nernst potential to determine

the oxygen transference number.

LaTa04 Based Materials - All rare earth niobates and tantalates

(RE)(Nb,Ta)04 display structures which are distortions of the CaW04

structure type, except for the tantalates of La, Ce, and Pr. In earlier

studies, we discovered a monoclinic-orthorhombic phase transformation in

these materials at high temperatures. The structure of the orthorhombic

phase was unknown. Attempts to grow large single crystals of LaTa04

from the melt (m.p. about 2100 °C) were unsuccessful as they could not

be cooled through the orthorhombic-monoclinic transition without shattering.

Small single crystal fragments were studied at 300 °C on a precession

camera and the space group of the orthorhombic phase was determined.

Its structure was determined by powder profile analysis in cooperation

with Dr. A. Santoro of the NBS Reactor Radiation Division, and found to

be of the BaMnF4 structure type.

Accommodation of excess oxygen in this structure was studied

by investigating the LaTaQ4 -ThTa04 . 5 and LaTa0 4 -LaW04 . 5 phase equilibria.

Up to 20% ThTa04#5 and 25% LaW04 . 5 can be accommodated in LaTa04 at

high temperatures, without any apparent crystallographic change. In the

process of the study, small single crystals of ThTa04>5 and LaW04 . 5 were grown, and their symmetry and unit cell dimensions determined. Due

to the refractory nature of the LaTa04 based compounds, acceptable highdensity ceramic pellets for conductivity measurements have not yet been

fabricated.

LaNb04 Based Materials - Accommodation of excess oxygen in

these CaW04 related compounds was studied by investigating the LaNb04

- ThNb04 . 5 phase equilibria. For compositions between La0 . 94 Th0 .o6 Nb0 4<03

and Lao , 63Tho. 37 Nb0 4<18 5 , and LaNbo.3 9 Wo . 11 0 4 .o55 ar, d LaNbo. 78Wo. 22 Q 4 .il> excess oxygen is accommodated by the formation of a 2 dimensionally

modulated structure. This structure was also observed for CeNb0 4 . O8 . The characteristics of the modulation were determined as a function of

oxygen excess in the thorium doped compounds. These are the first

reported oxide materials displaying two-dimensional modulation. A

computer program was written to allow the indexing of x-ray powder

diffraction patterns of modulated structures for up two-dimensional

modulation in a host lattice of average symmetry monoclinic or higher,

based on information obtained from single crystal diffraction photographs.

322
Polycrystall ine pellets in excess of 90% theoretical density

for CeNb04 , Lao . 9 Th # 1 Nb0 4 >O 5 » and Lao . 8 Tho. 2 Nb0 4 .i were produced by

sintering parti ally- reacted jet-milled powders at 1350 °C.

The reduced phase CeNb04 was studied at P n = 10 6 atm between

U2

400 and }000 °C. The conductivity of this material was quite poor, being

about 10 5 (ohm-cm) 1 at 1000 °C. Slow oxidation of the pellet at 520 °C

to the CeNb04<08 phase caused it to pulverize, precluding a measurement

of the conductivity of that phase.

The conductivities of Lao .9Tho.iNb04>O5 and Lao.gTho^NbO^i

were measured in air between 400-1000 °C.* They are about *2 x io 2 and

7 x 10 3 (ohm-cm) 1 at 1000 °C, respectively, with activation energies

of 1.4(1) eV, a rather typical value for oxygen motion. Although transference number measurements have not been made, the characteristics of the

electrode arcs in Cole-Cole plots indicate that at least partial oxygen

ion conductivity is present.

Structures of Other Tantalates and Niobates

R. S. Roth and R. J. Cava

In a continuing cooperative effort with Dr. A. Santoro, Reactor

Radiation Division, several large batches of single phase well crystallized oxides have been prepared and characterized by conventional

powder x-ray diffraction and by neutron diffraction total profile

analysis. A paper has been prepared and submitted with Dr. M. Marezio

of Grenoble, France, on the refinement of the structures of CeTa04 , CeNb0 4 , and NdTa04 at room temperature. Neutron diffraction data has

been collected and the structure at least partially refined for LaTa0 4

at 300 °C, above the monoclinic -> orthorhombic phase transition.

The problem of the neutron diffraction refinement of the structure

of LiTa3 0 8 is still not resolved. It now appears likely that LiTa3 0 8

may exhibit incommensurate diffraction effects which show up only with

neutron diffraction and not with conventional x-ray+ diffraction

(implying that most of this effect is due to the Li ions). In order

to check this hypothesis it is necessary to examine a crystal of

LiTa3 0 8 by a neutron diffraction Weissenberg (or other film) technique.

It is planned to attempt this experiment at Grenoble in the coming year.

An attempt will be made to solve the modulated structure of CeNb04<08

by determining the average structure from the neutron diffraction total

profile data and then looking at difference Fourier maps. The whole

problem of the structure of modulated incommensurate oxide phases is

currently under re-evaluation and the mathematical, x-ray and/or

neutron diffraction effects are being closely studied. Some of the

materials being studied in addition to CeNb0 4<08 and LiTa3 0 8 include

La l-xThxNb04+x/2

, LaTai-xMo

x

04+x/2’ Ta2°5 dopad with W0

3

° r ° ther

oxides, NbZr6 0 17 -type phases and 3A1 2 0 3

- 2S i

0

2 or other mullite type

compounds. A large review paper on "Thermal Stability of Long Range

Order in Oxides" by R. S. Roth has been prepared and submitted for

publ i cation.

323
Crystalline Ceramic Materials for (Simulated) Nuclear

Waste Disposal

J. L. Waring and R. S. Roth

It has been reported that synthetic rock (SYNROC) comprised of

selected minerals can accept into solid solution up to about 20% of high

level nuclear waste (Nature 278 , 219-223 (1979)). One method postulated

to form the SYNROC is by mixing appropriate amounts of Ti02 , BaO, Si0 2 , Zr02 , A1 2 0 3 , CaO, and K2 Q and heating to 1300 °C then slow cooling to

form the minerals hollandite (BaAl 2 Ti 60 16 ) , perovskite (CaTi0 3 ),

zirconolite (CaZrTi 2 0 7 ), Ba-feldspar (BaAl 2 Si 2 06 ) , kalsilite (KAlSi04 ),

and leucite (KAlSi 2 06 ).

Although these minerals have been characterized in the literature, the interactions between most of the various components has not

been investigated. Hollandite and zirconolite are the key components in

SYNROC. The hollandite (Ba

1+x

Al 2+x

Ti 6 _ x

0 16 ) is suggested to accommodate

K, Rb, Cs, Ba, Se, Pb, Mg, Co, N, Cu, Cr, Fe, Mn, Mo, Rh, Sn, and Zr.

The zirconolite (CaZrTi 2 0 7 ) is suggested to accommodate Na, K, Ca, Sr,

Ba, Pb, Y, Bi , Zr, U, Th, Ta, Nb, Ti, Fe, Mn, and rare earths.

The phase relationships between hollandite and zirconolite have

not been established. In a very preliminary experiment three compositions

were prepared including Ba

1+x

Al 2+x

Ti 6 _ x

0 16 with x = 0 and CaZrTi 2 0 7

. In

addition, the five starting components were formulated to yield an equimolar mixture of hollandite and zirconolite. The first specimen yielded

hollandite plus rutile, indicating that hollandite does not form in this

system with only one or less Ba. 2 ions per formula unit. The second

specimen yielded single phase zirconolite, as expected. The third

specimen was completely melted at 1450 °C, well below the melting point

of the end members, indicating the existence of a deep eutectic between

these two minerals.

Experimental results as mentioned above clearly indicate that

there is a need for considerably more experimentation prior to substituting

simulated radioactive waste materials into these minerals.

Crystal Growth, Synthesis, and Analysis

Energy Conversion Materials

W. S. Brower and H. S. Parker

The synthesis and crystal growth of phases for identification

and structural studies in support of NBS materials research programs and

in collaboration with other research laboratories on a national and international basis has continued. A variety of techniques have been utilized,

including melt and flux growth techniques as well as vapor transport

techniques. The crystals grown for in-house research have included the

silicate mullite (3A1 2 0 3

• 2S i

0

2 ) , its germanium analog (3A1 2 0 3 *2Ge0 2 )

,

l_a2W2 09 , ThTa0 4 ^ 5 and ThNb0 4<5 . The latter two compounds are of interest

as ionic conductors similar to the cerium tantalates and niobates.

324
Crystals of La 3 Ta0 7 and La3 Nb0 7 were grown and provied to

Dr. Jean Galy of CNRS, Toulouse, France, for structural basis. Also,

crystals of Hg2 Cl 2 were grown by a vapor transport method directly onto

fused quartz “whiskers" to make further handling during study unnecessary

(thus avoiding any stress of the crystal). These crystals were also

supplied to Dr. Galy for investigation of the structural nature of the

low temperature (~ 100 K) phase transition in this compound.

Some effort has been devoted to synthesis, crystal growth, and

phase identification in the complex system Ba0-Nd2 0 3 -Ti02. The barium

titanates are well-known dielectric materials and the recent work of

Dr. D. Kolar of the Josef Stefan Institute in Yugoslavia has shown that

very favorable dielectric properties exist in compositions in this ternary

system (Ber. Dt. Keram. Ges. 55 [7] 346-8 [1978], but the system has not

been systematically investigated. As part of a collaborative effort,

crystals are being grown of the reported ternary compounds and preliminary

structural investigations are being conducted at NBS. Further efforts

are in progress to obtain crystals and identification of other complex

phases in this system.

Corrosive Reactions in Oxides

H. S. Parker, R. S. Roth, and C. D. Olson

With NASA support, the investigation of the KFe02 -Fe2 0 3 portion

of the K2 0-Fe0

x system has been completed. The objectives of this study

are 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 of the study is to consider alternate techniques for

containerless processing.

It was found that chemical corrosion of platinum by compositions

in the 80-100 mole percent Fe 2 0 3 range was minimal at temperatures as high as 1600 °C, provided that the sealed container was of sufficient

strength to avoid rupture due to the oxygen released from the Fe 2 03 at

temperatures above 1J00 °C. The absence of attack was attributed to

the low amount of Fe 2 in the specimen under the given experimental

conditions. Because of excessive potassium volatility during heating

at low oxygen partial pressures, compositions in this system do not

appear practical for containerless experiments at this time. During

the coming year, the compositions of interest will be expanded to

include selected regions in the K2 0-Fe0-Si02 system and from these,

favorable compositions will be selected for containerless experiments

in continuing collaboration with NASA Marshall Space Flight Center.

325
Scanning Electron Microscope

L. P. Cook, T. Negas, D. B. Minor, and C. D. Olson

The scanning electron microscope has continued to provide essential

data for phase equilibrium studies. With this instrument the necessary

correlation between microstructure and microchemistry can be made. By

careful attention to operating conditions and methods of data reduction,

quantitative measurements of crystal /I i quid and liquid/liquid partitioning

for six elements in silicate melts as a function of temperature were

completed. These measurements have provided considerable information

on the high temperature solution thermodynamics of multicomponent K2 0-

rich melts. It is anticipated that, with the aid of appropriate software, quantitative analysis of oxygen content using the windowl^ss

+ energy dispersive x-ray detector will allow determination of Fe 2 /Fe 3 - ratio in iron-rich melts.

This facility was utilized extensively to examine electrode/insulator

materials tested at the U-02, Moscow, USSR, facility during Phase III

(and final) of the USA/USSR joint MHD effort (summer 1978). Electrodes

(36) were fabricated from doped-LaCr03 , LaA103 -LaCr03 solid solutions,

and doped-LaCr03 /Zr02 -based composites. Insulation was monolithic MgO

or MgAl 2 0 4. Additionally, the performance of the MgO-based insulating

wall provided by the USSR was evaluated.

326
STRUCTURAL METHODS FOR PROCESSING, MANUFACTURING, AND DURABILITY

The program of the Crystallography Group is applied to 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

12555. The objectives of the program are to: provide x-ray and thermal

expansion SRM materials; publish Crystal Data ; publish standard x-ray

patterns with JCPDS-International Centre; develop new high pressure

x-ray method for radial distribution of liquids, correlate with and

extend range of our viscosity measurements; determine structures of

compounds of interest to industry and government (FDA); develop measurement methods for selected area diffraction and elemental analysis;

and improve measurement methods by x-ray diffraction of spacings and / intensities.

Crystal Structure Analysis

A. D. Mighell, C. R. Hubbard, and J. K. Stalick

FDA Structural Work: During the year we have collaborated

with various scientists at the FDA, Catholic University, Cambridge

University (England), and the University of Groningen (Holland), to

solve structures of interest to the Food and Drug Administration.

In modern drug studies special emphasis is being placed on the

correlation of stereochemistry with the biological activity of a given

drug. Single crystal x-ray diffraction provides the structural data

required to establish the exact three-dimensional geometry of drugs

that are clinically active. From such data one can establish the basis

for rationally designed drugs with great potential for the treatment of

such diseases as cancer, Parkinson's disease, and schizophrenia. This

year x-ray work has been carried out on a compound closely related to

cyclophosphamide (an anti -cancer drug), and on two rigid analogs of

dopamine (an anti -Parkinson' s disease drug).

Anti-cancer drug [Collaborative effort with Prof. G. Zon and

V. Himes of Catholic University]: Cyclophosphamide (CP) is a well-known

drug which is effective for treating a broad spectrum of human cancers.

Among the numerous ring-substituted (CP) analogs that have been studied

recently, 4-phenyl cyclophosphamide (4-Ph-CP) has been found to be highly

active against lymphoid leukemia. Consequently an x-ray structure

analysis was carried out on 4-Ph-CP. Unambiguous correlation of stereochemistry and anti -cancer activity in the 4-Ph-CP system will add to a growing body of knowledge on CP and its derivatives and should lead to

more potent drugs for the treatment of cancer.

H Ph

H 0

Q

/

r^N(CH2 CH2 Cl) 2

CP 4-Ph-CP

327
Anti-Parkinson's disease drug [Collaborative effort with

J. Rodgers of Cambridge University and Alan Horn of the University of

Groningen]: The crystal structures of two tetraline derivatives were

determined as part of a study of structure-activity relationships in

psychotropic drugs. These rigid analogs of dopamine are especially

important as they allow one to correlate molecular conformation with

. clinical activity. Our structure work not only gave the conformation of

these dopamine analogs but also revealed a novel type of stereochemical

disorder in both structures.

Miscellaneous Structural Work: Because of the nature of our

single-crystal diffraction facility and our close ties with related

techniques [e.g. , powder diffraction, neutron diffraction, and neutron

profile analysis] many collaborative projects with other groups at NBS

and at universities are now taking place.

The Syntex diffractometer has been used to identify and characterize unknown crystals, to determine unit cells so that powder patterns can be indexed, and to collect sets of data. Sets of data have

been collected for Professor Stewart at the University of Maryland, for

Dr. Appleman of the Smithsonian Institution, for Dr. Mathau of the

Dental Association, and for Drs. Block and Piermarini. In the latter

case data were collected under varying conditions of pressure.

It is hoped that our collaborative work can be expanded and

that the x-ray facility can serve as an area facility. Such collaboration helps us to develop the necessary tools [hardware and software]

to solve diverse problems in materials science.

Lattice Theory [Collaborative effort with A. Santoro]: Reduction and derivative lattice theory have been applied to the registration of solid state materials; new techniques have been devised to

study intra- and inter lattice relationships.

a) Registration of solid state materials: A highly

sensitive method to identify (or register) solid state

materials has been devised. For each compound a solid

state registry number is assigned that is based on its

lattice and chemical composition. The method has been

extensively employed to routinely register materials

entering the Cambridge Crystallographic Data Base and the

NBS Crystal lochemi cal Identification Tables.

b) Symmetry determination: We have classified all materials

in the NBS Crystal Data File according to reduced form.

This classification has allowed us to make an analysis of

the relationship between the lattice metric symmetry and

the crystal -lattice symmetry. It was found that the

symmetry predicted from the reduced form is consistent

with the crystal symmetry in 97% of the cases. On the

basis of this analysis, a symmetry determination procedure that can be adapted to an automated diffractometer

has been devised.

328
c) Inter- and Intralattice relationships: In the study

of crystalline materials, it is often necessary to find

the relationships between two or more crystal lattices,

either identical or different from one another. Typical

cases in which a knowledge of lattice relationships is

required occur, for example, in the critical evaluation

of data to be included in such major compilations as the

Crystal Data and Powder Data Files, in the analysis of

twinning and coincidence-site lattices, in the study of

interrelated structures, in the evaluation of the results

obtained for powder indexing procedures, in singlecrystal di ffractometry , and in many other areas of crystallography.

A practical method to determine matrices relating arbitrary

cells of two or more lattices has been devised. The relevant properties

of the lattices can then be derived from the nature of the transformation

matrices.

This new method for establishing lattice relationships should

have an impact on the study of material properties and durability. The

method will be used to study coincidence-site lattice relationships, to

study the twin laws for materials in the Crystal Data file, to devise

better algorithms to index powder patterns, to register materials entering the crystallographic data files, and to identify unknown crystalline

materials.

Crystal Data

A. D. Mighell, J. K. Stalick, and R. J. Boreni

The purpose of the Crystal Data project is to collect, to critically evaluate, and to disseminte data on solid state compounds with

special emphasis on durability. During the year we have worked on a new

subfile of metals and intermetallic compounds, expanded our basis data

evaluation program, and constructed a computer file for the identification and characterization of solid state materials.

Metals and Intermetallic Data File: A computer data base of

critically evaluated data on metals and intermetallic materials is being

built in collaboration with Drs. L. Calvert and Yu Wang of the National

Research Council of Canada. This is a collaborative effort consisting

of several steps: data will be collected, abstracted, and edited in

Canada; a computer printout or a magnetic tape will be sent to NBS; the

data will be critically evaluated a second time by NBS editors and

computer routines; a computer data base will be built at NBS; publications will be derived at NBS directly from the metals data base.

Basic Data Evaluation Program [Collaborative effort with

C. R. Hubbard]: Our data evaluation program has been significantly ex- panded during this year. New routines to enhance the critical evaluation of data are being added. These routines are designed to check

329
the reported symmetry, to calculate figures of merit for the d-spacings

of a powder pattern, and to calculate a quality index for cell parameters. The evaluation program is designed not only to evaluate data,

but also to build a data base from which all products can be derived.

This program is designed to be used jointly by the Editors of the Crystal Data File and the JCPDS Powder Diffraction File,

Identification: Crystal! ochemi cal Identification Tables.

These tables will contain key crystallographic data on approximately

60,000 materials. The computer file will be finished in the Fall of

1979. From the computer file, a publication will be derived (in collaboration with B. B. Molino and C. Messina of OSRD) by computer typesetting procedures.

The file is designed so that one can identify an unknown

material from any primitive cell of the lattice. The computer version

of the file could be attached directly to an automated diffractometer.

It is planned to explore the feasibility of such an approach with the

Nicolet Co.

Powder Diffraction

C. R. Hubbard and S. J. Carmel

Standard patterns: Six associates of the JCPDS- International

Centre for Diffraction Data (M. E. Morris, Director; H. P. McMurdie,

Consultant; E. H. Evans; J. deGroot (Retired May, 1979); B. Paretzkin;

and M. D. Owen) continue to collaborate with two NBS employees (C. R. Hubbard

and S. J. Carmel) in producing powder diffraction data and in editing

and evaluating data from the literature. Section 16 of NBS Monograph 25

will be published in September, 1979. It is the 26th of the series of

"Standard X-ray Diffraction Powder Patterns." Section 16 contains 58

experimental patterns and 28 calculated patterns, as well as a review of

methods used at NBS for obtaining both the experimental and calculated

patterns.

The major emphasis of the JCPDS is to produce subfiles for selected

markets. Such subfiles enable a user to search for an unknown material

or chemical without the necessity of dealing with the entire file of

approximately 30,000 compounds. Subfiles currently available are: (1)

Frequently Encountered Phases, (2) Minerals, (3) Metals and Alloys, and

(4) NBS patterns. Future subfiles are forensic materials and ceramics.

M. E. Morris is the chairperson for reviewing and improving the Frequently Encountered Phases (FEP) subfile. Under her direction the

associateship is replacing poor patterns in the FEP subfile with high

quality patterns. Of the 58 experimental patterns of Section 16, Monograph 25, nearly 85% are for the FEP subfile. In FY 80 the majority of

the experimental patterns will be for this subfile. The other experimental

patterns will be minerals, forensic materials, or ceramics.

330
The majority of the calculated patterns were of drugs listed on the

Drug Enforcement Agency list which were also absent from the file. Data

for these calculations were obtained from the Cambridge Data Center.

JCPDS Activities: NBS staff members continue to participate in

technical activities of the JCPDS. C. R. Hubbard is chairman of the

Educational Subcommittee. This subcommittee has prepared a tutorial

workshop on use of the Powder Diffraction File (PDF) which was presented

to over 200 scientists at three national meetings. The subcommittee is

also committed to organizing scientific sessions at the Denver X-ray

Conference and other meetings such as the session on Crystallographic

Data Bases for Chemists to be presented at the ACS meeting in Washington,

D.C. , September 1979. In less than one year the powder diffraction

search/match component of the Chemical Information System (CIS - a coordinated package of over 10 chemical data bases organized by NIH and

EPA) has become the third most used component. A. D. Mighell and

C. R. Hubbard continue to advise on the development of the JCPDS-NIH/EPA

agreement to place the PDF on the Chemical Information System's international computer network. They also continue their efforts to improve

the editorial process of the JCPDS and serve on various subcommittees.

The JCPDS task group on data base design (C. R. Hubbard, chairman,

A. D. Mighell, member) has evaluated options for data entry. The

recommended choice is a CRT terminal with forms input capability and

local storage. A HP2645 terminal has been programmed and tested for

input to AIDS, the data evaluation program. To move to a computer based

data base AIDS must be expanded. Jointly with Crystal Data, new input

formats and data items have been documented. Programming modifications

and enhancements are to be completed by September 1979. The completed

program will be made available to the JCPDS and scientists throughout

the world. The use of a common program for data evaluation and data

base building will likely lead to data sharing and cross checking

between the JC and Crystal Data.

Symposium on “Accuracy in Powder Diffraction": The symposium was

held at the National Bureau of Standards, Washington, D.C., June 11-15,

under the sponsorship of NBS, the National Research Council of Canada,

and the International Union of Crystal lography. The chairman was

S. Block, and C. R. Hubbard was a member of the organizing committee.

Talks covered all aspects of accuracy in the powder method and various

applications. The proceedings will be published by the NBS and will be

available from the National Technical Information Service, Washington, D.C.

Guidelines for Publication of Powder Patterns: The ACA committee

on guidelines for publication of powder patterns (C. R. Hubbard, member)

presented a preliminary report at the ACA Winter meeting and a final

report at the NBS Symposium on Accuracy in Powder Diffraction. The need

for the guidelines is a result of the growing size of the Powder Diffraction File, the greatly increasing use of computer search/match

331
methods, and the recent developments in improved data collection. The

quality of the file of reference patterns is the limiting factor in

phase identification. Reference patterns from NBS are often far superior in both d-spacing and relative intensity values to those reported

in the literature. The proposals of the ACA committee, which closely

parallel the techniques and methods used at NBS, have been forwarded to

the ACA for presentation to the International Union of Crystallography.

Phase Identification: An unusually large number of samples were

submitted to C. R. Hubbard and S. J. Carmel for qualitative phase

analysis by powder diffraction. Included were samples of Si C (a or p

polymorph), compounds from ashing recycled oils, zinc phosphate samples,

and dental ceramics from Dental Research. C. R. Hubbard and C. R. Robbins

participated in a national round robin on analysis of low temperature

ash of coal. The main constituents found in the coal ash were quartz,

calcite, pyrite, illite, kaolinite, and marcasite. (Also see Materials

Characterization and Analysis - C. R. Robbins.)

Energy Dispersive X-ray Diffraction

F. A. Mauer

A detailed study of factors affecting intensity and resolution in

energy dispersive powder diffraction has been carried out in order to

optimize the experimental conditions for obtaining x-ray diffraction

data with the diamond anvil cell. Improvements in equipment and techniques have led to obtaining better data in less time and, thus, have

enhanced NBS capabilities for high pressure crystallographic studies.

The factors studied include size, intensity distrubition of the

white radiation source, absorption in the diamonds, beam divergence and

parti cal size of the sample, as well as collimator and slit system

design.

Radiation from a tungsten tube has been found to give the best

approximation to the desired white radiation source. The characteristic

lines of the L series of tungsten occur below 12.1 keV where the absorption in the diamond is so severe that no useful data could be

recorded in any case. A digital offset of 256 channels is used to

eliminate this useless portion of the spectrum.

A considerable enhancement in the intensity of the region of

interest in a diffraction pattern by a judicious selection of the

diffraction angle, 20, is possible. An improvement by more than a factor of ten can sometimes be realized. We have modified the design of

the diamond cell to provide an exit window for the diffracted beam

extending from 0 to 27° in 20. This extended range not only provides

the needed flexibility for optimizing 20, but also makes it possible to

observe reflections which would occur beyond the limit of the Ewald

sphere for CuKa radiation. We have also devised a graphical representation of powder patterns which is useful in selecting the best

diffraction angle to avoid interference from characteristic lines and

sample fluorescence. By plotting E versus 1 /sin 0 for each d^^ a series of straight lines through the origin is obtained which show at a glance the location of each diffraction line at any diffraction angle.

332
Because of the extremely small volume of the sample in the diamond

anvil cell, the number of crystallites is often too small to justify the

basic assumption of powder diffraction—that all possible orientations

are represented with equal probability. As a result, lines may be

missing, or their intensities may be greatly distorted. Increasing the

divergence of the x-ray optics is a possible approach to the alleviation

of this problem, but leads, in turn, to line profiles that may be shifted

with respect to the true energy calculated for a given d-spacing.

Powders must be ground to a particle size well below 30 pm (400 mesh),

or the sample must be oscillated to obtain reproducible intensities,

with none of the line missing. With these precautions, as well as accurate alignment of fine collimators to eliminate diffraction lines

from the gasket and scatter from the diamond, it is possible to obtain

good patterns with low background and well resolved peaks in about four

days. Results on CuCl , CdS, and ice VII are presented in the section on high pressure studies. Further, substantial reduction in the time

required to obtain diffraction patterns and improvements in their ac- curacy will have to await the availability of a synchrotron or rotating

anode x-ray source.

Standard Reference Materials

C. R. Hubbard

The powder diffraction SRM project began with the certification of

SRM-640 Si powder as a 20 standard. This SRM has sold over 550 units

since 1975. A large d-spacing SRM to supplement the Si powder has been

the subject of an extensive search. Criteria have been established and

several candidate materials identified (MoS2 , sodalite, phlogopite,

fluorophlogopite, muscovite, and acid phthalates). Sources of large

quantities of each of these materials are being located. By September 1979

one or two materials will be selected. Using powder and single crystal

methods the selected materials will be certified during FY80. The cell

parameters must be accurate to a few parts in 10 5

. To achieve this

level of accuracy improvements in determining peak location and calibrating the powder diffractometer are required. Least squares programs

for calibration purposes have been developed. Methods to locate peak

positions to a few thousandths of a degree have been surveyed. One or two methods will be implemented. For quantitative analysis and for

testing instrumental intensity response five materials were selected and

preliminary measurements were completed in FY78. To improve on accuracy

w*p 1 of the relative intensities (I ) and reference intensity ratio (I/Ic)

measurements a sample rotator has been modified to work with one of the

automated units. I re ^ and I/Ic certification will be completed in FY79.

The discrepancy between the experimental and calculated patterns of a-Al 2 Q 3 , the primary reference material for reference intensity ratios, has been

ascribed to aspherical electron density in preliminary work done collaboratively

with L. Calvert of NRCC. I/Ic values can be calculated from single

crystal structural data and a numerical constant based on the structure

of a-Al 2 0 3

. Reducing the error in the numerical constant from a-Al 2 0 3 will

reduce the error in derived I/Ic values and thereby lead to more accurate

333
quantitative phase analysis. The reference intensity ratio method of x- ray powder diffraction quantitative analysis is a fundamental constant

method for quantitative phase analysis. Measurement of these constants

has been improved at NBS and methods are reported in Monograph 25. NBS260 publication on use of 20 standards and intensity standards are to be

completed in FY79.

High Pressure Studies

S. Block, G. J. Piermarini, and R. G. Munro

During this year we have conducted a survey of the literature on high pressure research with the diamond anvil cell. The survey covered

the years 1960 through 1978. Figure 1 shows not only the importance of

the development of the diamond cell at NBS in the early sixties but

indicates the even greater significance of the NBS-pressure scale introduced during the period 1972-75.

The fact that the experimental chamber is easily and conveniently

accessible by radiation (light, x-rays) has stimulated research in

structure, phase transition, bonding, mass transport, and electrical

properties. Recently we have carried out work on viscosity, structural,

and electrical properties of semiconductors, compressibil ites of S 4 N4

and H2 0, and initiated work on the melting point of refractory metals.

Viscosity: The recently developed diamond anvil cell fallingsphere viscometer has been utilized to measure the pressure dependence

of the viscosity of stable and metastable n-butyl chloride. This

substance was chosen as being suitable for a cooperative intra-NBS

investigation of metastable states of matter. The equilibrium freezing

pressure (2.3 GPa) and the glass transition pressure (4.2 GPa) were determined at room temperature by separate measurements to identify the

region of metastability (2.3 GPa < p

< 4.2 GPa). The viscosity was then

.obtained starting at a pressure of 1.94 GPa. This transport property

was found to vary smoothly through the transition from the stable to the

metastable state.

The viscosity results for n-butyl chloride were also used in

conjunction with the critical point viscosity model,

H = A(l-P/P

g

)‘ v

where q is the viscosity, P 9

is the glass transition pressure, and A and

v are other parameters. Use of the model makes it possible to obtain a reasonable estimate of the glass transition pressure if the viscosity as

a function of pressure is known for sufficiently high pressures. Values

of P have been determined in this fashion for n-butyl chloride, 4:1

methanol-ethanol, and isopropyl alcohol, and the results have been used

to confirm the ruby line-broadening method of determining glass transition pressures. For the noted liquids, the model yields, respectively, 4.6, 10.2, and 5.1 GPa for P , and the ruby method yields 4.2, 10.4,

and 4.5 GPa. ^

334
Fig. 1

335
In addition to confirming the line-broadening method finding

P , the viscosity model might prove to be useful for describing the properties of lubricants. Since lubricants are used under conditions of

widely varying stresses, the value of the exponent in the viscosity

model could be an important consideration for evaluating the ability of

a lubricant to respond to the changes in the stress.

The temperature dependence of the glass transition in 4:1

methanol -ethanol was determind by the ruby line broadening method. At

-48 °C the glass transition is 5.65 GPa yielding APg/AT =0.68 GPa per

degree. This value agrees with values obtained at lower pressures for

other alcohols.

Metastable States of Matter: An energy dispersive x-ray

diffraction system is under development for use with diamond anvil

cells. Since diamond anvil cells without special design features place

unusually large restrictions on the acquisition of data, a theoretical

investigation is being conducted by R. G. Munro to examine the consequences of these limitations for radial distribution function analysis

and for cell designs.

An illustration of the nature of the problem created by a limited set of data can be given in terms of a two-dimensional information plane as shown in Figure 2. The plane is described by the polar

coordinates (r, 0) where r is a real space distance and 0 is an integration variable for computing a radial distribution function. The

.value of the RDF at distance r is obtained by means of an integration of

the information contained on the circle of constant r in the plane. The

variable 0 forms the integration variable extending from zero to 2ji.

The plotted points indicate the points in the plane at which experimental data have sampled the available information. The most reliable

calculations require information samplings from all quadrants of the

plane with an increasingly larger information density occurring as one proceeds from the first quadrant to the fourth. As an example, in the case shown, it can be seen at a glance that the computation for r=0.

1

will not be reliable.

The method of investigation is to form a comparison of the

reliability of various computational procedures and to construct the

comparison as a function of the degree of data limitation. An exact set

of data having an exactly known radial distribution function is used so that the absolute error can be determined in each case.

Cuprous Chloride: Electrical, optical, and x-ray diffraction

experiments have been carried out on cuprous chloride by us and

F. A. Mauer in cooperation with A. Jayaraman, T. H. Gabel le, and

G. W. Hull, Jr., of Bell Telephone Laboratories.

336
Fig. 2

337
The behavior of CuCl under pressure has received much attention recently, prompted by the reports that it undergoes a transition to

a metallic state at about 4.0 GPa.

The pressure dependence of the electrical resistance of CuCl

to pressures up to 14.0 GPa was measured using a recently developed twoprobe method adapted to the diamond anvil high pressure cell. An

improved version of this method which increases reliability of the

measurements, employs a nickel wire mesh as a substitute for the single

tungsten wire electrode. Two probe electrical resistance measurements

were also made in a diamond cell using an ungasketed anvil arrangement.

Bell laboratories also measured the electrical resistance of CuCl in a piston-cylinder device to 5.0 GPa, using a cylindrical CuCl sample

encased in a teflon sleeve and with copper contacts on either end

serving as electrical leads.

The results of our electrical measurements, which were made on four samples of CuCl prepared by different methods, do not show any

evidence for a "metal lie" Ha phase even after repeated cycling, as previously reported. No significant photoconduction effect has been

observed in the CuCl sample which was determined by carrying out the

measurements in the absence of light, in dim red light, and in white

light. In the experiments done in the piston cylinder device no large

resistance drop was observed in the range of 0.1 to 5.0 GPa, in agreement with our diamond cell results. Employing a polarizing microscope

and the ruby fluorescence method of pressure measurement, a transition

at 4.6 ± 0.2 GPa was observed in single crystal of CuCl in a hydrostatic

medium of. 4:1 methanol -ethanol

.

The results of our x-ray studies, using both film techniques

with ungasketed CuCl samples and a newly developed energy dispersive

method with gasketed samples, confirm the transitions from zincblende to

tetragonal structures at 4.4 GPa and from tetragonal to the NaCl type

structure at about 8.0 GPa. Our x-ray pattern of the black opaque phase

taken in an ungasketed diamond anvil consists of NaCl-type lines. We,

therefore, believe that in the NaCl phase of CuCl a disproportionation

reaction sets in, in the presence of large sheer stress. It is well

known that CuCl is unstable with respect to disproportionation. Possible disproportionation reactions are: (1) 2CuCl -» CuCl 2 +Cu°; (2) 3CuCl

Cu+

Cu++

Cl 3 +Cu° ; and (3) 4CuCl CuJCu^C^+Cu0 (5,16). In each

disproportionation reaction elemental copper is formed, and the presence

of a small amount of free copper (of the order of even a percent) could

cut off visible light transmission.

In summary, we found no evidence for a dielectric-metal transition either in our resistance measurements or optical observations in

CuCl up to 12.0 GPa under hydrostatic or quasi hydrostatic pressure

environment. We showed that the black opaque phase has the NaCl -type

structure and suggest that the opacity might be due to disproportion of

CuCl . to free
CdS: Electrical and structural properties of CdS as a function of pressure and temperature was undertaken with F. A. Mauer, (Sponsored by Department of Defense, Watervleit Arsenal). The semiconductorconductor transition was measured electrically, by energy dispersive x- ray diffraction, and observed microscopically. The transition is dependent on particle size. Single crystals transform at 2.65 GPa while

powders transform at 3.25 GPa. Interestingly the slope AP/AT is negative. At 100 °C the transition occurs at 2.49 GPa and at -44 °C the

transition is at 3.20 GPa. All measurements were in a 4:1 methanol

ethanol solution and therefore hydrostatic. The glass transition of

this solution at -48 °C was determined to be 5.65 GPa. Electrical

measurements were carried out in the dark because CdS is highly photoconductive. The two methods of electrical measurement discussed in the

CuCl section were carried out to determine whether there was significantly different conductivity perpendicaular and paralled to the pressure axis. No significant difference was found and therefore the transformation is uniform and not in a layered configuration.

X-ray diffraction studies were carried out above and below the

transition. The transition is from the zincblende structure where each

atom is tetrahedrally coordinated to the sodium chloride structure where

each atom is octahedrally coordinated. Preliminary results indicate

that the low pressure phase has a volume compressibility of -3.1% to the

transition and an additional -19.3% upon transforming to the high

pressure form. This large volume change probably explains the increase

of x-ray 1newi dth we_ observed when. the. sample, was rapid ly decompressed.

S4 N4: The compressibility of S 4 N 4 was studied with J. K. Stalick

(sponsored by Department of Defense, AROD) to a pressure of 4.2 GPa

using the new single crystal diamond anvil pressure cell. A single

crystal of S 4 N4 was first mounted on a glass fiber and the unit cell

determined by centering 15 reflections on the Syntex diffractometer.

The cell parameters of the monoclinic unit cell (a = 8.791(1), b = 7.1735(13), c = 8.700(1) A; 0 = 92.47(1)°) agree with those obtained

from a single crystal placed within the pressure cell with no external

pressure applied. Unit cell data were also determined at pressure of

1.3, 3.0, 3.7, and 4.2 GPa. At 4.2 GPa the cell parameters decrease to

a = 8.156(21), b = 6.667(5), c = 8.162(8)A; a = 89.93(7), c = 91.74(16),

o Y = 89.90(15)°. The volume of the unit cell decreases from 548.1(2)A3

o to 443.7(13)A3

, a reduction of 19%, while the a and c axial lengths

become equal within the accuracy of the measurements. The monoclinic

metric symmetry is retained to 4.2 GPa.

It is planned to attempt compressibility measurements at

higher pressures. This may not be possible owing to the increased

broadening of the reflections with increased pressure, which results in

the larger standard deviations reported.

ICE VII: In collaboration with G. E. Walrafen of Howard

University, high pressure Raman and x-ray diffraction experiments were

339
carried out on water. The group at Howard University carried out Raman

studies in a diamond anvil cell. They determined that the 0-H vibrational

frequencies of ice VII shifts downward with pressure and they expected

that the shift would correlate with 0-0 distances. We carried out

powder diffraction studies using wavelength dispersive film and energy

dispersive counter techniques. These x-ray studies were carried out to

20.2 GPa. As ice VII is body centered cubic the 0-0 bond distance is

simply related to the cell constant d0

_ o = V3/2 A0

. The cell dimensions

o o change from 3.355 A at 2.36 GPa to 3.035 A at 20.2 GPa indicating a A/Vo

of 26% and a shortening of the 0-0 bond distance from 2.906 A to 2.638

oA. There is a sharp break in the compressibility at approximately 15.86

o GPa with very little change afterwards in A°(3.052 to 3.035 A). This

probably indicates that the repulsive forces become highly significant.

Melting Point: Work was initiated on the pressure dependence

of the melting point of refractory metals (Sponsored by Department of

Defense, Watertown Arsenal). The first material to be studied is

tantalum. This is a joint effort with A. Cezairliyan of the Thermophysics Division of the Center for Thermodynamics and Molecular Science.

They will use their millisecond heating apparatus to determine the

melting points. Resistive heating will be used. A sample configuration

has been designed, built, and tested at ambient pressure outside the

cell. The sample configuration gives an excellent melting point and a diamond anvil cell has been modified to accept the sample and be com- patible with the millisecond temperature apparatus. Experiments are currently underway to test these modifications.

Thermal Expansion

T. A. Hahn

Thermal expansion measurements have been somewhat curtailed because

of manpower limitations. Nevertheless, quite a range of materials was investigated, mainly on request of research groups in and outside NBS.

The thermal expansion of Incoloy 800 was measured for the Fracture and

Deformation Division. Incoloy 800 is a high temperature corrosion

resistant alloy that is being extensively used in high temperature

energy related plants. The thermal expansion was measured on a candidate MHD electrode material spinel 9[Yo<8S Cao .i5Fe0 3 ] + CaZr0 3 to support work in our Division. Plus, measurements are in progress on the

recertification of SRM 736 Thermal Expansion Copper. The original stock

of the material has sold out.

As has always been the case, we continue to support other NBS

activities by providing thermal expansion data and consultation on expansion measurements. For example, R. S. Polvani (Fracture and Deformation Division) is concerned with the long-term stability of beryllium

used in gyroscopes. One source of instability was shown to be the

thermally generated microstresses in the Be due to natural inclusion of

BeO with its much lower thermal expansion. A paper on this topic, in

collaboration with R. W. Armstrong (University of Maryland) was presented

to the Maryland Institute of Metals.

340
Consultation with R. P. Whitlock of the Dental Section on the

measurement of the thermal expansion of dental porcelain has contributed

to the understanding of the failure of porcelain coatings on base metal

dental protheses.

We also consulted with a variety of people who were trying to

resolve measurement problems or merely contemplating setting up thermal

expansion laboratories. A few of these include G. Gill and M. Haller of

Dentsply International, W. Wagenbreth of P. T. B. , and A. Clark of NBS

Boulder. Requests for information on thermal expansion and its measurement or requests for NBS papers on thermal expansion were supplied to

about twenty different people this year. A couple of notable requests

were: 1 ) information on the thermal expansion of fused silica at low

temperature that is of critical importance in an apparatus designed by

B. Cabrera of Stanford University for a test of general relativity; and

2) correspondence with S. J. Bennett of NPL on the thermal expansion of

copper and the possibility of joint thermal expansion standards with the

U. K.

We also continue to support ASTM activities in Committee E37 on Thermal

Expansion. Presently both the dilatometric and interferometric test

method are being revised and a new test method is being written for TMA

apparatus which is extensively used in the plastics industry.

Materials Characterization and Analysis

C. R. Robbins

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 collaborative effort with the Office of Recycled Materials

to study power plant ash has been initiated. The study will involve

development of quantitative methods of phase analysis by x-ray powder

diffractometry 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 byproducts.

A collaborative study with the Smithsonian Institution

(V. Steponaitis, Predoctoral Fellow in Anthropology) of prehistoric

pottery from Moundville, Alabama, is near completion. Moundville is the

second largest Mississippian site in eastern North America and was

occupied between A.D. 900 and A. D. 1600. A quantitative mineralogical

341
study by optical and x-ray methods has identified the raw materials

used, and the range of firing temperatures reached in making the pottery. Physical property measurements (made in collaboration with

another group at NBS) have been correlated with the phase composition of

the pottery.

Work with the Fracture and Deformation Division (E. R. Fuller, Jr.)

has continued in the form of phase analysis of candidate refractories

and cements for energy-related applications. Analysis was by conventional x-ray methods on materials previously subjected to extreme

envi ronments.

A collaborative study with the NBS Data Center for Energy

Applications (H. M. Ondik, R. C. Dobbyn) has been completed. Chemical

reactions that occurred in the refractory lining of the Conoco Coal

Development Company's Gasification Pilot Plant (Rapid City, South Dakota)

after nine months of operation were studied by optical, SEM, and x-ray

diffraction methods.

342
PROPERTIES, STRUCTURE, AND STANDARDS FOR GLASS AND OPTICAL MATERIALS

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; to study relationships between properties,

structure, and constitution; to assist the glass, ceramic, and optics

industries; to provide standard reference materials of use to glassrelated and other industries; and to characterize glass and crystalline

materials for use as optical components and solid state electrodes.

Physics and Chemistry of Glass

W. K. Haller

Glass, because of its chemical inertness, electrical resistivity,

transparency and unique forming characteristics, is one of the most widely

used materials. Its applications range from architecture, packaging of

beverages and pharmaceutical materials, heat insulation, reinforcer in medical

devices, and lasers, to countless applications in the electronics

industry. Every year brings new uses of glass, such as encasement of

nuclear waste, solar energy devices, laser fusion target shells, etc.

Glass is furthermore found in nature as obsidian, and abundant waste

products such as coal and blast furnace slags are mainly in the glassy

state. The unique structure of glass permits its synthesis over a wide range of stoichiomeries. This characteristic and the fact that it can be produced with extreme homogeneity and in many shapes has made

glass the favorite material for analytical standards. There are many

defense and national security-related applications of glass. NBS is

considered as a national center for glass science and applications in

the U.S.A. and its Glass Section has a particularly close relationship

with industry and other government agencies.

Vaporization from Glass Melts

D. M. Sanders, J. T. Wenzel, and W. K. Haller

Sodium borosilicate vaporization is of interest to the glass

industry because compounds containing boron and sodium appear to have substantial vapor pressures under industrial conditions. These vapors are quite

corrosive to tank refractories and the loss of boron is of concern because

of its increasing expense and scarcity. The addition of small amounts

of boron to soda-lime-silica glass lowers melting and fining temperatures

without changing viscosity-temperature characteristics in the glassforming

range, potentially leading to substantial energy savings. Boron is also

used as a major component in glasses having superior chemical durability

for medical fluid containers, chemical lines, and glass fiber thermal

insulation. These glass compositions are also resistant to thermal

shock, making them useful for applications such as laboratory and kitchenware.

343
This past year was devoted to establishing experimental procedures

for the study of vaporization of boron-containing species from glass melts.

Pure boric oxide was chosen as the first system of study in order to

establish the collection and analysis techniques. First it was established

that steam cleaning of the collection tubes (coated with condensed boron

compounds) was necessary to insure the complete transfer of boron

compounds from the tubes to an aqueous analyte solution. Second, atomic

absorption spectroscopy was found to be the only suitable analytical

technique for the determination of boron concentrations in the analyte

solution. Atomic emission spectroscopy was tried, but sodium gave

unacceptably high interferences with the boron signal. A graphite

flameless atomizer emission technique was tried also, but severe memory

effects from one run to the next were observed, making this method

unacceptable too. Sodium interference in boron analysis by atomic

absorption was determined to raise the apparent boron concentrations

by less than 10%, for equimolar concentrations of sodium and boron in

the analyte. Boron did not interfere with sodium analysis using atomic

emission spectroscopy.

After the boron analysis technique was perfected, the reactive

vaporization of molten boric oxide with water vapor was studied, in

order to collect reference data on a pure substance for future use in

a comparison with boric oxide solutions. The temperature of measurements

was 1100 °C, and water vapor partial pressure was varied between 1 torr

and 200 torr. It was found that for low water vapor partial pressures

the log-boron vs. log-pressure dependence was nearly linear with a slope

of one-half, while for higher water vapor partial pressures the slope

was three halves. This is consistent with a model which proposes the

existence of two vapor species above a boric oxide glass melt: HB02

is predominant at low water vapor partial pressures, and H 3 B0 3 is

predominant at high water vapor partial pressures.

Finally, the reactive vaporization from a 16.5-16.5-67.0 mol %

sodium borosilicate glass melt was studied, also as a function of the

water vapor partial pressure. In contrast to pure boric oxide, the

vapor pressure of both sodium and boron was constant for all water

vapor partial pressures studied. This interesting result is in apparent

contradiction to published experiments, performed, however, under illdefined conditions. Additionally, the vaporizing species was found to

be equimolar in boron and sodium, suggesting that it is probably sodium

borate.

344
Glassy Multicomponent Films

D. M. Sanders and E. Farabaugh

In fiscal year 1980, we will start the production of glassy thin

films by simultaneous vapor co-deposition from electron beam and electrically

heated sample sources. The purpose of this program will be to explore glass

formation by vapor deposition, to investigate the structure of such glasses

and to produce amorphous optical reflection and anti reflection coatings

which have physical properties which meet or exceed those found for

presently used polycrystalline films. In the structural study, glassy

thin films will be prepared using molecular beam co-evaporation of glassforming constituents. The composition of the molecular beam mixture will

be monitored and controlled by a microprocessor-based mass spectrometer

and a quartz-crystal oscillator controller. The composition of the

resulting thin films will be analyzed using ESCA, SIMS, AUGER, ISS, and

Atomic Absorption Spectroscopies. The beam density and composition

will be systematically varied at different substrate temperatures to

obtain conditions where preferential bonding will manifest itself in the

dependence of film composition on vapor composition.

If this approach proves successful it will provide an experimental

basis for determining which, if any, of the many theories of glass structures

is correct. In addition, the knowledge of stable compositions in multicomponent glass systems will provide detailed information concerning

compositions having maximum homogeneity and minimum absorption and scat-

'll eri ng;"3uch data' wi Ti'iTe-'QSgftrT fDr pnroduc iny 1 uw^ -ttrgs^rrte-gra^

In fiscal year 1979, we completed construction of the facility

to prepare and analyze amorphous thin films. The facility consists of a deposition chamber having a Titanium sublimation pump (1000 1/s), a Cryopump (4000 1/s), and a Turbomolecular Pump (450 1/s). The chamber has

all metal seals and is capable of an ultimate vacuum of 5 x 10

^

mb. The

chamber contains fixturing to monitor the reflected and transmitted light

during deposition to determine when 1/4 wave optical thicknesses are

obtained. To carry out depositions, the chamber contains a triple electron

beam evaporation module to permit simultaneous evaporation from three

crucibles. In addition, heated boat sources can be added as needed. All

sources are controlled using process controllers driven by the output

from a microprocessor mass spectrometer. A quartz-crystal monitor is

used to determine the thickness of the co-deposited film.

The deposition chamber is connected to a surface analysis system

capable of AUGER, SIMS, ISS, and ESCA spectroscopies. Transfer from the

deposition position to the analytical position is accomplished using a 40" magnetic linear manipulator without exposing the deposited film to

atmosphere.

345
Viscosity of Glass Near the Strain Point

D. R. Swerdlow, J. T. Wenzel, and D. J. Cronin

This project involves the design and operation of a beam-bending

viscosimeter for the rapid determination of glass viscosity in the

10 lo -10 15 poise range (sag point to strain point. The apparatus is

particularly suitable for glasses (such as fluorophosphates) which cannot

be drawn into fibers because of steepness of viscosity curve and/or

surface degradition, and, since only small samples are required, for

glasses which cannot be cast in large pieces.

Several modifications to the apparatus were made this year. The

transducer and head assembly were improved, resulting in more precise

measurements and less apparatus drift, and the sample holder was improved,

which gave increased dimensional stability and defined distances more

precisely. These improvements made possible the absolute measurement

of the viscosity of NBS SRM 711, in addition to the slope of the logviscosity vs. temperature curve. Agreement with published values for

the viscosity and its temperature dependence was excellent. Studies

on fl uorophosphate glasses showed that they increase viscosity by a factor of 10 for each 12 °C decrease in temperature. Because of this

strong temperature dependence of the viscosity of the fl uorophosphate

glass, the temperature uniformity limits the precision of measurements

severely.

Standard Reference Materials for the Glass Industry

Liquidus Temperature SRM

M. J. Cellarosi

The liquidus temperature of a glass is the minimum temperature

at which a melt can be held for a long period of time without formation

of crystals. This property is especially important to the glass industry

for development of new glasses and to insure high productivity with

minimum expenditure of energy.

During the year, NBS research continued to identify and rectify

flaws in the gradient method testing procedures. Several factors were

identified as causing experimental difficulties and faulty liquidus

determinations. Therefore, applicable ASTM procedures were tightened.

These factors involve the shape and age of platinum boats, test length,

methods of visual observations, steepness of temperature gradient,

temperature determinations, thermocouple calibrations, surface vaporization

and crystallization, and crystal phases observed. Because of these findings,

two participating laboratories are repeating the round robin. NBS is

cooperating with these labs to resolve their difficulties.

Other factors were identified by NBS to restrict liquidus

precision. These factors were discussed at meetings of ASTM Committee

C14.04 (Physical Properties of Glass). They include the dependency of

liquidus on the thermal history of sample during test, and on the rates

of crystal growth and solution. Because of these dependencies, liquidus

can be affected by a particular temperature gradient, heat capacity, and

recovery rate for different furnaces.

346
An impressive number of laboratories have cooperated in the

round robin activities related to this SRM project. The results represent

their best efforts in terms of the method and equipment available. The

gradient method is common practice and is widely used in research and

production throughout the glass industry. The glass selected for this

SRM is a soda- lime glass, whose liquidus temperature represents the

major part of glass production (e.g., window and container glass). In

this context, activities to produce this SRM were started by NBS, and

certification should be completed by the end of December 1979.

Viscosity SRM

D. J. Cronin and M. J. Cellarosi

NBS Glass Viscosity SRM's have an important role in glass research

and manufacture. The viscosity of glass is of practical importance in

all stages of the manufacturing process. This importance is expected

to increase as greater emphasis is placed on productivity and better

quality for glass products.

The glass industry relies on NBS to provide a long-term supply of

viscosity SRM's. Because these SRM's sell well, NBS inventory is shrinking and renewal will be necessary in the next few years. Enough lead

time is required to plan and carry out new viscosity SRM programs.

During the year, modern torque measurement instrumentation was

purchased. This equipment was checked and was found to be in proper

working order. Plans for the new facility have been made and work was

started on the building of a new high temperature furnace. This new

facility will enable NBS to carry out measurements at higher temperatures

than the old apparatus and produce data with greater precision and

accuracy with less labor.

347
Dielectric Constant SRM

M. J. Cellarosi

The glass industry through ASTM Cl 4. 04 (Physical Properties of

Glass) lists this project as a priority item.

The proposed SRM is needed to upgrade and standardize measuring

systems for dielectric constant of glass. This need was confirmed

by a survey conducted by NBS on behalf of ASTM. An SRM for this

property will support the expanding role of glass in countless

electrical /electronic applications (e.g. , insulation, controlled

electrical leaks, windows for electro-magnetic waves, energy storage,

envelopes for devices, substrates, encapsulation, capacitors, etc.).

Moreover, this SRM will help in energy conservation efforts (e.g.,

low- loss insulators and dielectrics).

Glass Dielectric Constant SRM's are also expected to be of

interest to the plastic industry. The inherent long-term stability of

glass makes it superior to plastic standards for calibration purposes.

NBS heads and ASTM task group on round robin testing, and on the development of standard methods for the determination of the

dielectric constant of glass.

During the year, a preliminary round robin program was organized.

This activity is now in progress. For this purpose SRM 711 samples

were distributed to the participating laboratories. Tentative test

methods proposed by NBS were accepted by ASTM. These testing procedures

specify three- termi nal measurements with a guard electrode to minimize

the effect of edge and ground capacitances. At this time two participating labs (NBS and Corning Glass) have reported sets of measurements.

Data are encouraging as they agree within 5%.

Research is in progress to generate standard procedures that

yield the greatest precision. In this effort NBS will study data and

test details from participating laboratories.

This work is important to resolve dielectric constant

measurement discrepancies existing in the glass industry.

348
Plans for Future SRM's

Melt Density SRM: There is a limited industrial interest

in a standard glass with certified high temperature (molten state) density.

The transport of glass through the various zones of a melting furnace

and much of the stirring (convection) is determined by density gradients

in the liquid glass. Designers of novel glass furnaces aim at closed

constructions which are energy saving and less polluting. They also

like to save floor space by increasing the height of me! ter units. Such

designs require greater predictability of flow patterns and, hence, a better knowledge of melt densities as functions of temperature and

composition.

Melt Electric Resistivity SRM: Increased use of electricity

in glass melting (increased furnace capacity, less air pollution,

shortage of gas and oil) has led to a demand for a melt resistant SRM.

Alternate Liquidus Temperature SRM: The present SRM

candidate glass for liquidus temperature is a typical commerical composition and therefore of interest to the industrial community. However,

because it is a commercial composition it presents certain difficulties in

it measuring the liquidus temperature. Therefore it was sought to develop

a series of glasses specifically for use as liquidus temperature SRM's

which would have sharp, easily definable endpoints and could be used for

temperature calibration of the equipment used to determine liquidus

temperature.

A hot stage furnace was constructed and was used to make preliminary

liquidus temperature measurements. It also proved useful in observing the

crystallization and vaporization behavior of the glasses.

The glasses were to have the following properties:

1) liquidus temperature in the range of commercial glasses; 2) distinctive

easily recognized primary phase, one which could easily be distinguished

from surface crystallization; 3) crystallize easily, but not so readily

that crystals form on cooling as the sample is removed from the furnace;

4) nucleation occurs in the bulk glass; 5) good durability, to avoid

changes with time that could affect crystallization behavior; and

6) minimum vaporization losses at the liquidus temperature to avoid

composition changes that could alter crystallization behavior or obscure the crystallization end point.

The initial phase involved the melting and testing of

several congruently melting compounds that would form glasses and have

liquidus temperatures in the desired range. Several of the compositions

were then altered in an attempt to meet the overall property requirements.

Overall a total of twenty-two glasses were melted and tested. While

the results to date appear promising further work will be required

before certifying any of these glasses as SRM candidates.

349
Glass Standard Reference Materials Liaison

M. J. Cellarosi, W. K. Haller, and D. J. Cronin

Close relations with the glass industry, R&D organizations,

and active participation on various ASTM committees and other standard

bodies were maintained. These activities keep NBS abreast on the needs

of science and industry, and enable NBS to carry out effective SRM

programs that are responsive to the most important needs of both

producers and users of glass.

The glass industry through ASTM Committee C-14 on Glass and

Glass Products strongly endorses NBS to play a leading role in development of glass SRM's and related measurement methods. Industry and users

of glass rely on NBS participation and leadership in standards activities

because of NBS neutrality and reputation as a research organization. In

this context, our laboratory routinely reviews and generates inputs

on methods and specifications on glass and related products. Frequent

technical consultations are given on the use and applicability of SRM's

and on present and future needs on standardization.

Publicity literature was issued to reflect SRM updating. This

included a section on glass SRM's for the 1979 ASTM Annual Book of Standards.

Several technical meetings on SRM activities, glass properties, specifications

glass recycling, and nomenclature and definitions, were organized on behalf

of ASTM and the glass industry. NBS is also coordinating activities to

establish an industry-sponsored research associate program on glass SRM's at

NBS under the auspices of ASTM.

Other Glass Standard Reference Materials

Glass SRM's for Small Particle Analysis

D. H. Blackburn

Continued interest in this work has expanded the need for

different glass matrices. New matrices were developed in the following

glass systems Ge02 ~Li 20—

B

2 O 3

— AI 2 O 3 , P 2 O 5 — AI 2 O 3

— Na20 and Si 02 ~Li 20 -B 203 - Efforts will be made to include a wide variety of elements in these glasses

with 15-25 elements added in 1 atomic percent amounts. The use of glasses

for microanalysis standards has expanded rapidly and considerable future

forgrowth is foreseen. At present 10 glasses are available from NBS as Research Material No. 30, Glasses for Microanalysis, and the same glasses

as Research Material 31, Glass Fibers for Microanalysis. Standard Reference

Material 470 has been issued as Mineral Glasses for Microanalysis.

Presently work is progressing to issue 15 glasses as a Standard Reference

for Microanalysis that have a certified chemical analysis. Several talks

on this subject were given by collaborating members of the Center for

Analytical Chemistry.

350
Fluorescent Glass Bead Standards

D. H. Blackburn, 0. J. Cronin

Work has been continued in the development of fluorescent

glasses and glass spheres. As mentioned in previous reports, these glasses

have two major applications. One is for the purpose of marking valuable or dangerous materials and the other is for use as fluorescent standards

for various instruments used in the physical and biological sciences.

Future efforts will be directed toward increasing the size of the sphere

producing apparatus in order to produce spheres in larger quantities

and in controlling the size range depending on the application. Consideration is being given at this time to issue glass spheres as an SRM for

calibrating mi crospectrofluori meters. A report acknowledging our work

was published by J. R. DeVoe, D. M. Sweger, and R. A. Velapoldi

("Intruder Detection Using Trace Constituent Analysis," NBSIR 78-1510-

NBS Law Enforcement Standards Laboratory).

X-ray Energy Spectrometer Windows

D. H. Blackburn and D. A. Kauffman

We have developed an X-ray emission standard reference material

for the calibration of windows in x-ray emissive instruments. A glass

consisting of (wt %) Si02 -42.50; Ba0-2.00; Ca0-1.50; Mg0-20.00; Zn0-20.00;

B 2 0 3 -10.00, and Li 2 0-4.00 was found to have the proper emission characteristics and chemical durab fifty. It is planned to issue this glass

in the form of 25 mm diameter disks which are 3 mm thick. It has

been assigned the SRM-number 477. Production has been started and the

first casts have been found to have satisfactory homogeneity. Several

committee meetings on this subject have been attended by staff members

and a paper (see "Other Activities") was given at an NBS-held Symposium.

XRF Spectrometer Thin Film Standards

D. H. Blackburn

An important objective of this program is to develop thin film

standards containing various elements which can be certified for elemental composition. An NBS certified thin film standard can serve the x-ray

community by providing an accurate basis for the calibration of x-ray

spectrometers, especially for assessing the quality of air-pollution

abatement programs. Presently, calibration is performed using commercially

available thin film standards which are not traceable to any NBS standard.

During the past two years, we have explored the possibility of producing

thin glass films of known elemental composition using a focused ion-beam

sputtering technique. This work has been fully described in detail in

the NBS/EPA Energy/Environment Reports of January and June 1977, and

January and June 1978. Presently, the results look promising in that

it appears that this method is suitable for producing an NBS certificate

thin film standard. We are currently determining if glass films containing sulfur and phosphorus can be fabricated by this technique.

351
Special Glasses

Glasses for High Power Lasers

W. K. Haller, J. T. Wenzel, and D. H. Blackburn

The Glass Section has continued to collaborate with Lawrence

Livermore Laboratory (LLL) on the development and property measurement

of laser glasses for energy generation by laser fusion. This year most

glass melts were made for the investigation of lasing ion behavior in

different glassy environments; physical property measurements (primarily

viscosity and refractive index) were continued also. In addition, the

Glass Section consulted on technical problems related to laser glass

for both LLL and the Department of Energy (DoE).

During the past year the Glass Section melted 81 experimental

laser glasses for LLL and laboratories associated with LLL. Most glasses

were fluorophosphates, phosphates, silicates, or borates which had been

doped with rare-earth ions such as neodymium. Several unusual glasses

were melted also. Studies made on these glasses resulted in five publications and six presentations by the LLL staff in which the NBS

contributions were acknowledged.

The Glass Section has concluded its effort to develop

fluorophosphate glasses with low non-linear refractive indices, because

it was felt that the upper limit of improvement had been reached. The

compositions which the Section developed have been chosen by the glass

industry as base compositions for glasses which will be produced

commercially for use as laser rods and windows, and Faraday rotators.

A summary of this work has recently been published.

The “interim durability standard," a test for fluorophosphate

glasses developed previously by the Glass Section, continues to be used

by the laser glass community as a measure of the resistance of fluorophosphates to chemical attack. Recently, it has been applied to

beryllium fluoride glasses as well.

352
The Glass Section is continuing to develop the capability to make

optical measurements on beryllium-fluoride-based glasses provided by LLL.

These glasses have such low refractive indices and high Abbe numbers

that most commercial refractometers cannot measure these properties,

and commercial immersion and contact liquids also do not exist. The

Section has procured several inert liquids identified last year as being

promising candidates for immersion/contact liquids. The fused silica

vee-block for the Glass Section refractometer , which was designed and

let to contract previously, is nearing completion, and should enable

the desired refractive index measurements to be made.

The Glass Section continues to consult on glass-related matters

for LLL and DoE, both through periodic visits by one staff member

(W.K. Haller) to LLL and by telephone and letters. Examples this past

year include a study of film formation on laser glasses, diagnostic work

on microscopic inclusions in new, commercial fl uorophosphate laser

glasses, polishing of fl uorophosphate laser glasses, and the production

of hollow-glass micro balloons for laser fusion targets. Additionally,

the Glass Section supplies technical advice to the Director for Laser

Fusion at DoE on an on-going basis and participates in technical meetings.

The Glass Section has studied the viscosity, crystallization,

and annealing behavior of one prototype fl uorophosphate laser glass. The

temperature-viscosity relationship in the 10° - 102 poise range was

determined by using the rotating bobbin method and in the 10 lo -10 15

range it has been determined provisionally using the beam-bending technique (see other Section). Annealing studies showed that this glass

could be made essentially strain-free after annealing conditions had

been optimized. These studies confirm that, with respect to these

properties, fl uorophosphate glasses are suitable for use in high energy

laser applications.

The Glass Section has begun a program of research on optical

coatings for high-energy laser glasses; this is described in another

Section.

The Glass Section, at the request of the DoE, organized and

hosted a two-day meeting of all DoE contractors involved in the laser

fusion-high energy laser program. The meeting had four sessions: laser

glass development (infrared, primarily; also visible and ultra-violet);

coatings for use in the infrared; ultraviolet lasers and coatings; and

advanced projects. Attending the meeting were 65 persons representing

25 governmental, industrial, and academic laboratories.

353
Municipal Waste Utilization

M. J. Cellarosi

Under the Resource Conservation and Recovery Act of 1976, the NBS is

required to provide guidelines for the development of specifications for

materials recovered from wastes.

In the area of glass reclamation, NBS is cooperating with ASTM

Committee E-38 on Resource Recovery, the glass industry, and reclamation

facilities, to write test procedures that assess the usefulness of

recovered glass principally for reuse in container manufacture. In these

endeavours, NBS developed a test for refractory analysis in recovered

glass that yields acceptable precision levels. This method was accepted

by ASTM E-38.

NBS is also cooperating with ASTM and the glass industry on studies

that attempt to identify any major technological problems that might be

encountered when using recovered glass in manufacturing of containers.

The objective of these efforts is to assess the significance of these

problems as potential limits on the use of reclaimed glass. Examples

of such problems or barriers to recycling are the influence of color

mixture and refractory contamination on glass production.

Color mixed glass when added to a batch formulated for a particular

glass color can be a problem. Main coloring agents used in glass

container manufacture are oxides of iron and chromium. Thse agents are added in small quantities to the batch. Specific glass colorization

is greatly complicated when color mixed glass is used in the recycling

process. This is because the amount of colorants in the mixture can vary considerably in the course of the continuous manufacturing process.

354
Refractory contaminants (e.g. , pieces of ceramic ware, gravel,

concrete tile, spark plugs, etc.) are especially troublesome in glass

manufacture. These particles, depending on their size, oftentime do not

melt in the glass furnace. When this happens the particles become

solid inclusions or "stones 11 in the glass product. Stones affect the

mechanical strength and aesthetic quality of glassware.

During the year our laboratory evaluated cullet samples from a demonstration facility. Separation of non-glassy components by particle

size indicated unacceptable levels by industry standards of magnetic,

non-magnetic, and refractory contaminants. Also, numerous crucible

melts were made and results showed a high incidence of stones, although

the quality of glass excluding the stones was acceptable. It should be

emphasized, however, that laboratory melts do not represent precisely'

actual production processes, and therefore, they can only be indicative

of manufacturing trends. More work is needed in this area to correlate

lab melts and production recycling recovered glass.

At present, two large-scale reclamation facilities are scheduled to

come on stream in the next few months. One such facility is the $80 million

project at Hempsted, Long Island, New York. This facility will use improved glass-sorting equipment designed to separate glass by colors

(e.g., flint, amber, and green). Importantly, this plant should show

considerable progress in controlling refractory contaminant levels.

Other reclamation plants are scheduled to open during the next few

years. The glass industry plans to recycle more glass and advancements

in recovery technology are needed to insure that industry is provided

with a high grade, consistent, and long-term supply of cullet.

355
Optical Materials

Optical Materials Characterization

A. Feldman, R. M. Waxier, and M. J. Dodge

Basic optical data are needed for predicting the performance of

optical components and in particular components made of optical materials

that are continually being developed. Examples of recently developed

materials include, "reactive atmosphere processed" (RAP) KC1 and KBr,

chemical vapor deposited (CVD) ZnSe and ZnS, fusion cast CaF2 and SrF2 , hot forged KC1 and CaF2 , and neodymium doped phosphate and fluorophosphate laser glasses. Many of the new materials were developed for use in

high average-power laser systems. Absorption of intense laser radiation

propagating through a component produces a thermal gradient in the

material that causes optical path variations over the component aperture.

These optical path variations are due to four effects: the direct change

of index with temperature dn/dT, the change of thickness due to thermal

expansion, the stresses induced by the thermal gradients, and the change

of thickness due to the thermally induced stress. In laser systems for

fusion research, the laser rods and discs are subject to stresses due to

clamping and to thermal gradients induced by flash! amp pumping. In other'

systems, optical components are subjected to index variations due to

varying environmental conditions.

An important highlight was the publication of a Technical Note (see

publications) summarizing the data obtained under this project. Room

temperature values of refractive index as a function of wavelength were

presented for the following materials: commercially grown KC1 , reactive

atmosphere processed (RAP) KC1 , KC1 nominally doped with 1.5% KI, hot

forged CaF2 , fusion cast CaF2 , CaF2 doped with Er (0.001% to 3% Er),

SrF2 , chemical vapor deposited (CVD) ZnSe (2 specimens), and ZnS (CVD, 2

specimens). Data for the thermo-optic constant (dn/dT) and the linear

thermal expansion coefficient were given for the following materials over the temperature range -180 °C to 200 °C: A1 2 0 3 , BaF2 , CaF2 , CdF2 , KBr,

KC1, LiF, MgF2 , NaCl , NaF, SrF2 , ZnS (CVD), and ZnSe (CVD). The piezooptic constants of the following materials were presented: As 2 S 3 glass,

CaF2 , BaF2 , Ge, KC1 , fused Si02 , SrF2 , a chalcogenide glass (Ge 33%, As

12%, Se 55%) and ZnSe (CVD).

Piezo-optic Studies in the Infrared

R. M. Waxier and A. Feldman

Interesting new experimental results have been obtained from the

measurement of the piezo-birefringence coefficients, qn~qi 2 and q44 , of

the alkaline-earth fluorides, CaF2 , BaF2 , and SrF2 , in the infrared. For

the first time, a significant infrared dispersion in the coefficients has

been found due to the effect of stress on the transverse optical phonon.

356
Two groups, Humphreys and Maradudin at the University of California

at Irvine, and Bendow, Gianino, Tsai, and Mitra of RADC and the University of Rhode Island, have calculated the effect of the transverse optic

phonon on the infrared dispersion of the photoelastic coefficients of

binary compounds based on expressions for the interionic potential and

the interionic dipole moment. Earlier work done at NBS on the piezooptic constants of KC1 suggested that the proposed models were inadequate.

However, these results were based on measurements made at only two wavelengths, 3.39 pm and 10.6 pm, with He-Ne and C0 2 lasers, respectively.

It was felt that a more adequate test of the basic phenomenological model

should involve more detailed dispersion data in the infrared at many

wavelengths. We decided to study the stress- induced birefringence

(piezo-birefringence) of the alkaline-earth fluorides in the infrared for

three reasons: 1) These are important optical materials for both the

infrared and the ultraviolet. 2) The positions of the transverse optic

phonon frequencies of these materials fall in a region where the desired

dispersion effects should be observable. 3) The materials have sufficient strength to withstand the stresses needed for observing a measurable effect.

Figure 3 shows recent experimental data obtained for the piezo-birefringence of CaF2 , BaF2 and SrF2 as a function of wavelength. The dispersion observed is significant, and, in fact, one of the coefficients

q 44 for SrF2 is seen to change sign. Most recently, we have seen this

effect in CaF 2 as well. The curves were drawn through the data visually;

however, a computer program has been written that will be used to fit the

dispersion data to a phenomenological model based on oscillator strength

changes and phonon frequency shifts.

Optical Bistability

A. Feldman

As an offshoot of the program on optical materials characterization,

a contribution has been made in the field of optical bistability. An

optically bistable device is a device that can exist in either of two

modes. At low input optical power levels, the device remains in a nontransmitting mode. If the input power level is gradually increased,

to a certain critical power level, the device switches to a transmitting

mode. As the power level is decreased, the device remains in a transmitting mode until a lower critical power level is reached, at which

point the device switches to its nontransmitting mode. It had been shown

earlier, elsewhere and independently by us, that a Pockels cell with

appropriate feedback can exhibit optical bistability. Furthermore, we

had shown that such a device will act as an ultral inear modulator, that

is, the nonlinear dependence of the output signal on an input signal can

be made arbitrarily small compared to the linear dependence of the

output signal on the input signal. In addition, such a device exhibits

differential optical gain and power limiting.

357
'

’r
In a paper published this year, we have shown that the performance

of a bistable optical device can be significantly altered if the transmission function is made to depend upon a linear combination of the input

power and output power. When this modification is made to a device based

on a Pockels cell the following can result: 1) Bistable device — the

system response more closely approximates a step function. 2) Power

limiter — optical -power regulation can be improved at output-power

levels close to the input-power level. 3) Ultral inear amplitude modulator — the operating point of the device can be maintained at the

inflection point of the response curve, where the linearity is best.

Analogous modifications can be made to advantage on other bistable

optical systems.

Optical bistability will eventually become important because of the

large growth in optical communications and optical signal processing. It

does away with the need for conversions between electrical and optical

signals.

Future activities:

These will center on two areas: optical characterization and

research on bulk optical materials, and optical characterization of thin

dielectric films to complement the thin film deposition facility under

construction.

Research on bulk materials will center on dispersion effects in the

thermo-optic and piezo-optic coefficients due to electronic and phonon

processes.

Optical characterization of thin films would include: guided wave

techniques for measuring refractive index, absorption and Raman scattering; vacuum calorimetry or photoacoustic spectroscopy in combination with

tunable infrared lasers (color center lasers) for determining absorption

mechanisms; ellipsometry for determining optical constants.

Refractive Index

M. J. Dodge

High precision measurements of refractive index were performed for a number of government and private users. Twelve vee-block prisms to be

used for refractometers were measured at 16 wavelengths between 0.4047

and 1.083 pm for The Ceramics, Glass, and Solid State Science Division

(project coordinated by J. T. Wenzel) and Muffaletto Optical Co. The

index was determined for four immersion liquids at three wavelengths and

at four temperatures for the State of Texas Department of Public Safety,

to be used in crime laboratory identification of glass. Four liquids

were measured from 0.21 to 0.5461 pm, at two temperatures for Los Alamos

Scientific Laboratory, for dosimetry purposes. Other work on refractometer test plates for quality control in industrial production of glasses,

corn syrup, cosmetics, and pharmaceuticals was carried out. The indices

of the ordinary and extraordinary rays in MgF2 were determined from 0.21

to 6.0 pm as an aid in the optical design of windows and other components.

359
Optical Nondestructive Evaluation

G. S. White and A. Feldman

The use of optical techniques for nondestructive evaluation (NDE) of

materials is growing in importance. For example, holographic interferometry has become a standard procedure for detecting flaws in tires.

Optical scattering techniques are in use for high-space detection of

flaws in hypodermic needles and artillery shell casings. Speckle interferometry is being developed as an optical NDE tool to complement holography. It is the purpose of this project to provide a sound scientific

basis for optical NDE methods.

At present, the focus of our program is on the study of light

scattering from surface flaws. A scattering apparatus has been con- structed for this purpose. In preliminary scattering experiments con- ducted with this apparatus, the beam from a C0 2 laser source was propagated normal to the surface of a brass specimen containing a groove. The

groove with dimensions approximately 50 pm wide, 50 pm deep and 1 cm long was produced by spark erosion. Scattered light within a solid angle of

2 x 10 5 was measured as a function of the angle between the scattered

beam and the incident beam in a plane perpendicular to the specimen

groove. These measurements define a scattering function.

Representative data for an angular scan are shown in Figure 4. The

structure in the scattering function resembles the diffraction pattern of

a single slit, which is to be expected by application of Babinet's principle. From the spacing of the minima in the curve a’nd using the formula

for single slit diffraction, one calculates that the width of the groove

should be 52 pm, in close agreement with the approximate dimension given

above.

An interesting feature in Figure 4 is the double peak to the right

that appears near the scattering angle 0 = 17°. This structure appears

to be a property of the groove because when the specimen is rotated 180°

about the normal to specimen surface, the double peak shifts to the left

near 0 = -17°. This suggests that the scattered light contains more

detailed information about the groove structure.

In the course of setting up the scattering experiment, it was found

that the system alignment was for more critical than initially suspected.

For example, if the groove was not normal to the scattering plane but

deviated by only 0.3°, the scattering function would become grossly

distorted and assymetric. Furthermore, assymmetry was observed in the

scattering function when the axis of rotation of the detector did not

coincide with the groove.

360
(SiiNn aavi aiisnhini

361

Figure

4.

Typical

scattering

data

showing

the

double

peak

shifting

from

the

left

hand

side

(LHS)

of

the

sweep

to

the

right

hand

side

(RHS)

as

jthe

slit

is

rotated

180°.

The

lower

overall

intensi

for

the

e=0

scans

also

demonstrates

the

neep

to

monitor

beam

power

continuously.
Improvements of the present scattering system are presently being

made. A greater emphasis is now being placed on alignment. A special

alignment system has been constructed so that the axis of rotation of the

detector can be made to coincide with the groove to within 50 pm. A

further improvement we are making is the replacement of a manual rotation

mechansim, which made measurements extremely time consuming and tedious,

with a stepper motor rotation mechanism. This latter improvement should

make possible future automation of the system by microcomputer. Furthermore, we plan to monitor the output wavelength of the C02 and the output

intensity.

Plans: We plan to measure the scattering function of well characterized grooves possessing various cross-sectional shapes and sizes. The

dependence of the scattering function on the polarization of the incident

and scattered radiation will be examined. These measurements are expected

to be important in two areas: the detection of flaws in metal surfaces;

the determination of the scattering characteristics of defects in optically

finished surfaces, with possible implications for the present dig and

scratch standards.

Raman Scattering

M. I. Bell

Significant improvements have been made in the capabilities of the

NML Raman Spectroscopy Laboratory. The range of operating wavelengths

has been extended, and new software has been developed for the laboratory

minicomputer. Spectra can now be acquired and stored in digital form and

subjected to various types of quantitative analysis. These capabilities

have been used to good advantage in several recent investigations.

An examination of the effects of ion implantation in GaAs has shown

that above a critical dose a continuous amorphous layer is formed which

exhibits a Raman spectrum identical to that of amorphous films produced

by sputtering. Annealing by pulsed laser irradiation partially restores

the crystalline order, as indicated by increased intensity in the optical

phonon peak, but considerable disorder remains, with roughly 75% of the

total scattering intensity still to be found in the broad bands characteristic of the amorphous phase. This result helps to explain the fact

that laser annealing yields material of lower conductivity than would be

obtained if all the impurities introduced by implantation had been made

electrically active.

362
In collaboration with G. Walrafen and B. N. Krishnan (Howard University) and D. M. Sanders and S. W. Freiman, a preliminary study was

carried out to determine whether Raman spectroscopy can be used to study

the mechanism of stress corrosion in glasses. A stress apparatus was

designed and built which permits Raman spectra to be obtained from a small volume at or near the tip of a slowly propagating crack in a glass

sample.

Results on silica glass indicate a very small increase near the

crack tip in the strength of minor features in the spectrum which have

been attributed to defects, probably involving bonds of the form Si-OH.

The observed changes were close to the limit of experimental error, but

reproducible and in the expected direction. Further measurements and

careful quantitative analysis will be required to confirm these results.

An apparently more promising approach would be to use thin glass films in

which larger regions of high strain can be created. If the exciting

laser beam can be made to propagate as a guided wave in such a film, the

interaction volume could be made quite large. A prism coupling device

for launching guided waves in thin films was constructed and demonstrated

recently, and a proposal is being prepared in cooperation with A. Feldman

to seek support from the Director's Reserve for optical studies of thin

films by infrared and Raman spectroscopy.

Studies of the phase transitions in several families of improper

ferroelectrics have been initiated. Spectra obtained above and below the

parae VeetrTe**

p

3-ar.t r i r -tranci ti qjt_ temperature in s evera \ meta 1-

halogen boracites and propionates reveal the changes in the number"a ncl”'’"" symmetry of Raman-active modes expected on the basis of the changes in

crystal structure found by x-ray diffraction. Variations in the frequencies of certain modes within the boracite family seem to show

regularities which may yield information on the nature of the atomic

motions in these modes and differences in chemical bonding among the

members of this family. Careful measurements of the temperature dependence of the Raman frequencies are needed to help establish the correct

form of the free energy to be used in thermodynamic analyses of these

materials. For this purpose, a high-stability, high-precision oven has

been designed and built, and measurements will begin shortly.

363
Although Raman scattering is not generally regarded as a tool for

quantitative analysis, D. Diller of NBS, Boulder, suggested that it could

be used to determine the composition of hydrocarbon mixtures (such as liquified natural gas), where it might have advantages over gas chromatography (no sample extraction required) or infrared absorption spectroscopy (sensitivity to N2 ). A feasibility study was performed in

collaboration with Dr. Diller and R. F. Chang (Thermophysics Division),

and it was found that gas phase mixtures of up to five components at

pressures of 1-10 atm could be analyzed to give the relative concentrations of any two components with an accuracy of about 1%. Evidence

was obtained indicating that the measurement accuracy was not limited by

signal fluctuations due to the statistical nature of photon counting

detection but rather by mechanical instabilities in the optical system.

This observation could have important bearing on the potential of Raman

spectroscopy for quantitative analysis, and it may be possible to pursue

this question further in connection with high- temperature studies of

methane proposed in collaboration with T. Kashawagi (Fire Science Division

[NEL]) as part of a competence building initiative in the field of turbulent combustion.

In recent weeks, a study of impurity modes in silicon was begun in

cooperation with R. Forman (Electron Devices Division [NEL]). Initial

measurements on boron-doped samples have revealed only one of the two

peaks generally reported for this impurity and attributed to its two

isotopes. Further measurements on samples of various impurity concentrations and with dopings of isotopically pure boron will be needed to

determine whether the conventional assignment is indeed correct.

Properties of Pyroelectrics

M. I. Bell, M. I. Cohen, and D. Horowitz (in cooperation with

A. Shaulov, G. M. Loiacono, and W. A. Smith of Philips Laboratories)

Results of previous work on the pyroelectric and dielectric properties of ferroelectrics were analyzed, and a manuscript was prepared

describing the improved dynamic pyroelectric response technique employed

and typical results for proper and improper ferroelectrics. This paper

will appear in the Journal of Applied Physics (July 1979). The implications of this work in the selection of materials for detector applications were described in a paper "Improper Ferroelectrics for Pyroelectric Detection of Infrared Radiation," by A. Shaulov, W. A. Smith,

G. M. Loiacono, M. I. Bell, and Y. H. Tsuo, which was presented by

Dr. Shaulov at the International Symposium on Applications of Ferroelectrics, Minneapolis, Minnesota (June 14, 1979). Further refinements

in the experimental technique have been devised and demonstrated, and

completion of the apparatus awaits incorporation of a microprocessorbased system for control and data acquisition, the components of which

have just been delivered.

364
Analysis of the thermal and dielectric properties of LiKS0 4 and

LiCsS04 was completed and a paper describing these results was submitted

to the Journal of Solid State Chemistry. A similar study of LiNH4 S0 4

and its deuterated analogue (submitted to Ferroelectrics) established

that the low-temperature phases of these crystal (below about 10 °C) are

polar (pyroelectric), contrary to previous reports based on optical and

x-ray techniques. This result forces us to revise our understanding of

the phase transitions in these materials, and efforts are being made to

formulate a phenomenological theory to describe them.

Although previous work has emphasized the very different dielectric

and pyroelectric behavior of proper and improper ferroelectrics, our

recent analysis of the thermal properties (entropy and specific heat) has

drawn attention to the fact that in many cases these properties will

reflect the behavior of the primary order parameter and exhibit the same

temperature dependence in all types of ferroelectrics. The consequences

of this observation are being examined carefully in the hope that they

will lead to a unified treatment of both proper and improper ferroelectrics and ferroelastics.

Theoretical Modeling in Eddy Current NDE

A. H. Kahn and R. A. Spa!

We have completed the calculations of the impedance of a coil which

contains a conducting cylinder with a long radial surface crack. The

'csrcirrarro nr-mrh

employed an eigenfunction expansion of the magnetic field in the conductor, with the expansion coefficients determined by the fitting of

boundary conditions on the surface and in the crack. The second method

of calculation was by conversion of the problem to an integral equation

for the eddy current density on the surface of the conductor. The

advantage of the second approach is that it is applicable to any twodimensional shape of cross-section of the conductor as well as offering

an independent check on the first method of calculation.

The results of the calculations for the cylinder with a crack are shown in Figures 5 and 6. The fractional charge of the real (resistive)

and imaginary (inductive) parts of the impedance are shown plotted

against the ratio of crack depth to radius (d/a) for a wide range

of values of the ratio of radius to skin depth (a/5). For the case of

a tight crack these calculations represent a complete solution of the

problem. Open cracks can be treated as individual cases by the integral

equation method.

365
The results described above are all related to the detection of long

flaws in bodies of uniform two-dimensional cross-section, such as rods,

cylinders, and strips. With this accomplishment as a start, we plan to

go on to three-dimensional problems which are of greater interest. A

possible problem for attack is the configuration in which an eddy current

probe is passed above a conducting plane with a crack or other defect on or beneath the surface. Such problems have, in the past, been treated

under the approximation that the defect size was small with respect to j the skin depth. By extension of the integral equation method we plan to

treat such problems more generally.

«/8

Figure 6. Fractional change of the imaginary

part of the impedance plotted against the ratio

of crack depth to radius (d/a) for various

values of the ratio of radius to skin depth

(a/5). The factor (ua/d) provides normalization

to unity for infinite (a/5), i.e., for infinite

frequency.

Figure 5. Fractional change of the real

part of the impedance plotted against the

ratio of crack depth to radius (d/a) for

various values of the ratio of radius to

skin depth (a/5). The factor (ira/d)

provides normalization to unity for

infinite (a/5), i.e., for infinite

frequency.

366
Electrocatalysis

M. I. Cohen

This research is directed at the need for data required for the development of materials to be used in fuel cells. The primary effort has

been pointed toward methods for measuring the characteristics of potential substitutes for expensive Pt as the electrocatalyst in hot phosphoric acid fuel cells. The work has been partially supported by the DoE

and has been performed in collaboration with members of the Chemical

Metallurgy group in the Metal Science and Standards Division.

During the past year work has proceeded along two complimentary

paths. On the one hand, we are studying the electrochemical properties

of some of the refractory hard metals. Some results on one of these

(Mo-|_ xW

xC) will be outlined here.

We have compared the rates of anodic oxidation of H 2 on WC in

phosphoric acid electrolytes at varying temperatures with the rates

observed under the same conditions over the WC isostructural alloy

Mo-j_ xW

x C). The ternary catalyzes the reaction as effectively as WC,

apparently by the same mechansim, and is equally tolerant of CO entrained

in the H2 feed. Our experiments indicate that proton discharge is the

rate limiting step in the reactions on these carbides and that limitations

on performance are caused by the paucity of active sites. This implies

the possibility of improving the performance of these electrodes by

appropriate modifications in the preparative technique.

The second aspect of this program is an on-going commitment to

improving our measurement system and to maintaining its capabilities in

a manner as close to the state-of-the-art as possible. This has resulted

in an upgrading of the system to include a larger read-write memory

capacity, a floppy disc unit, and an improved converter board. Programming improvements include a 128 point Fast Fourier Transform (FFT)

program (in BASIC).

Along with this work, an educational program in Digital Electronics

and Microprocessors in Instrumentation, was started. Although originally

intended for members of the Fuel Cell Research Group, it soon grew.

Successful completion of a series of 13 seminars occurred in June.

In addition, a video recording and display unit for use in high

pressure viscosity measurements has been constructed. Initial programming

of the unit is almost done. Advisory and support services to a number of

groups within and outside the Division has continued. Preliminary design

consultation on a field system for a DoT Program on Measurement of

Corrosion of Reinforcing Bars in Concrete has been completed.

367
Plans: 1. Operation and performance checks, programming and permanent

installation of the improved converter board is expected in

1st quarter.

2. Additional software needed for this system (and others) will

be written.

3. Impedance measurements on Zr02 electrolytes.

4. Design and construction of the Rebar corrosion measurement

system will begin in 1st or 2nd quarter.

5. Concurrent to (4) a similar system to be used for measurements of corrosion in Concentric neutral Electrical cables

(for EPRI) is to be designed and started.

368
DURABILITY OF CERAMICS AND GLASS IN SERVICE ENVIRONMENTS

The objective of this task is to develop test methodology and collect

critical data for the assessment of high temperature materials in MHD and

coal gasification environments. The Division's activities in these areas

are part of two programs that cover several Divisions of the Center for

Materials Science: MHD-material s and Clean Utilization of Coal. Both

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. As discussed in the preface for this

Division, the DoE program was sharply reduced this past year.

Electrical Conductivity and Electrochemical Effects of MHD Related

Materi al

s

W. R. Hosier, T. Negas, and G. S. White

Electrical conductivity is one of several fundamental physical

properties of materials, and other physical properties can be either

studied or derived through electrical conductivity. In the development

of MHD power generation systems the electrical conductivity of the component materials of the channel area must be known in order to design

the system. Not only is the magnitude of the conductivity of prime

importance but the conductivity process must be understood. When

different materials are placed in contact with each other, chemical

changes may take place at the junction boundaries especially at elevated

temperatures likely to be found in an MHD channel. These chemical

changes are accelerated when large currents are passed through the

boundary and can result in gross electrochemical degradation of the

materials. Much of this past year's work has been involved in the study

of the conductivity of electrode materials and in the conductivity and

the conduction process in various coal slags as well as the reaction

between these slags and the electrode materials.

Very high density (<95% of theoretical) YOO3 1 has been prepared

by thermal sintering techniques and the electrical conductivity has been

measured over a temperature range of 25 °C to 1650 °C under several

partial pressures of oxygen. As can be seen from Figure 7, the conductivity in the oxidized state is satisfactory over the entire temperature range to serve as an electrode or lead out material. Preliminary

tests on this material immersed in molten slag containing an added 20

w/o K2 S0 4 and subjected to an impressed voltage and current for 20 hours

indicate considerable cathode damage but low anode damage. Oxygen pressures are higher on the anode where the electrode materials should

remain highly conducting.

Initial measurements on coal slags were made on Eastern slags with- - out added potassium in an effort t§ understand the conduction mechanism,

particularly with regard to the Fe 2 /Fe 3 ion ratio. Specially designed

crucibles and measuring techniques have shown the slag conductivity to

be entirely predictable depending on the previous treatment. The con369
370
ductivities below about 1000 °C fall on two distinct curves of either

high or low conductivity (Fig. 8) depending on the temperature from which

they were quenched to 900 °C. Those samples quenched from above 1375 °C

form the high conductivity slag containing Fe 3 0 4 and a slight amount of

another unknown spinel while those quenched from below 1375 °C form the

low conductivity slag containing no crystalline Fe 3 0 4 but only CaAl 2 Si 2 0 8

. These measurements were done in air. The measurements repeated in an atmosphere of 5 x 10 6 atm 02 in nitrogen showed no detectable change in

conductivity magnitudes or change in the critical temperature of 1375 °C.

Ferric- ferrous ratios are being measured by wet chemistry methods.

Reference

1. Preparation and Properties of Yttrium Chromite Ceramics , T. Negas,

W. R. Hosier, NBS, and L. Domingues, Trans-Tech, Inc., 4th Interantional

CIMTEC Energy and Ceramic Conference, Faenza, Italy, May 28-31, 1979.

In Situ X-ray Diffraction Analysis

F. A. Mauer and C. R. Robbins

In coal gasifier systems, reactive gas components in the process

atmosphere react with the protective refractory liner at high pressures

and high temperatures. Degradation of the ceramic liner frequently

results. — -

In a joint NBS-DoE program described under Task 12155 test methods

and equipment have been developed to obtain critical data on the strength

and phase composition of refractories under simulated gasification

conditions. In situ x-ray diffraction analysis was used to determine

phase composition and to detect polymorphic transformation at temperatures to 1000 °C and pressure to 1000 psi in atmospheres containing

steam C0 2 , CO, and H2

. All specimens were of compositions within the

system Ca0-Al 2 0 3 -Si02

. They included a high alumina castable (94.4 w/o

alumina, 4.5 w/o lime) and a calcined flint caly castable (55.5 w/o

alumina, 4.5 w/o lime, 37 w/o silica) as well as special compositions

corresponding to known bonding phases.

A series of experiments in which a test bar approximating the

composition CAS2 was heated in steam sheds new light on factors affecting the development of strength in calcined flint clay castables.

An unfired test bar, compounded from CA 25 cement and silica in the form

of quartz, was exposed to steam for a total of 500 hours in two series

of experiments. The rather surprising observation is that a metastable

phase, ca8 Si 5^18 > not previously encountered in these studies, was

formed at approximately 160 °C in preference to hexagonal or tri clinic

CAS2. This new phase persisted to 525 °C and then reacted with Si0 2 over a 100 °C range to form tri clinic CAS2 (anorthite). The formation

of Ca8 Si 5 0 18 suppressed the formation of the important CAS 2 bonding

phase by tying up the available calcium. Its occurrence is expected to

delay the development of strength in green bodies and is, therefore,

believed to be undesirable.

371
372
Data Centers for Materials and Components for Fossil Energy

Applications

H. M. Ondik, T. A. Hahn, 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 cooperatively 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 responsible for compiling information on construction materials for coal conversion use and MHD

power generation. This Center is largely staffed by personnel from

Ceramics, Glass, and Solid State Science Division, Ondik, Hahn, and

Perloff, with Feinberg (562). The major source of the data has been the

Center‘d library of DoE materials research contractors' reports. There

are currently some thirty projects generating materials properties and

performance data for coal conversion use and about a dozen projects

covering MHD power generation. Other sources are being explored and

other reports of pertinent work being sought to expand the Center's

information base.

Computer storage of the materials properties data base and access

to it will be controlled using a commercially available data base management system. A request for proposal for computer vendors' services

has been circulated, proposals have been received, and the first step of

the techni cal eval uati on process hag bgen accompJ ished. _ As_ s oan_ as the

final evaluation can be made and a contract let for computer service,

the building of the data base can be fully implemented.

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.

The computer file currently contains some 500 reported failures.

Several draft reports have been prepared on failure topics, and information is regularly supplied for the Failure Experiences feature of the

DoE Materials and Components Newsletter , published by Battel le-Col umbus.

Queries are addressed to the Center concerning failure information and,

during the last year, the Center responded to 68 requests for information and supplied over 2800 reports and abstracts summarizing the details of in-service materials performance.

373
During the past year, staff of both Centers, under the direction of

R. C. Dobbyn (562) completed a detailed study of the performance of

materials used in the Conoco Lignite Gasification Pilot Plant (C02

Acceptor Process). The study is based on the information contained in

plant operating records and is not limited to reported failures. The

report also contains the results of the visual examination, sampling,

and laboratory study of the refractory lining of the plant gasifier

vessel. Staff of the Failure Information Center have completed a feature article summarizing the performance of the refractory lining

which will be submitted for publication in the Materials and Components

Newsletter .

The Materials Properties Data Center currently has under way a state-of-the-art review of materials for MHD power generation. The

review will deal with materials for open-cycle plants and omit materials

for closed-cycle and 1 iquid-metal -cycle plants for which there is inadequate information at present.

The two Centers are currently engaged in preparing sections of a Construction Material s Handbook for Coal Gasi fi cation-- Performance and

Properties Data . This Handbook will contain information gained in

practical plant experience and also the results of materials research

and testing programs. It will deal with the information in the context

of the separate component areas of coal gasification plants, and will

draw from this information an indication of possible candidate materials

of construction. A separate section of the Handbook will include ex- tended data for the chemical, physical, and mechanical properties of the

candidate materials.

Slag Viscosity

W. S. Brower and 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.

374
Other Division Activities

Invited Talks

Application of High Temperature Chemistry to Energy Related

Systems

Miami University, Oxford, Ohio

T. Negas

October 1978

^Electrochemical Phase Equilibria

Fall Meeting of the American Ceramic Society, National Bureau

of Standards, Gaithersburg, Maryland

L. P. Cook

November 1978

*Y-Deflection Modulated SEM Images in the Evaluation of Ceramic

Surface Finish

Symposium on Science of Ceramic Machining and Surface

Finishing II, National Bureau of Standards,

Gaithersburg, Maryland

L. P. Cook

November 1978

Application of High Temperature Chemistry to Energy Related

Systems _ ^ _

'The "Amen can' University ," ¥as'hfng'torT,''DT“C.

' " * ’

T. Negas

December 1978

Thermal Stability of Long Range Order in Oxides

U. S. -Japan-Austral ia Joint Meeting, Symposium on Long Range

Order in Solids, Honolulu, Hawaii

R. S. Roth

March 1979

Modulated Structure vs Superstructure: Systems Involving

ABX^

+x

Phases

Modulated Structure Symposium, American-Crystallographic Assoc.,

Kailua Kona, Hawaii

R. S. Roth

March 1979

Phase Equilibria and Crystal Chemistry in the System YFe0 3 -CaFe 2 0

The American Chemical Society, Honolulu, Hawaii

R. S. Roth

April 1979

375
*Liquid Immiscibi 1 ity in the System K2 0-CaQ-FeQ -Mg0-Al 2 0 3 -Si02

Annual Meeting of the American Ceramic Society , Cincinnati , Ohio

L. P. Cook

May 1979

Conductivity Mechanisms in the Superionic Phases of Agl and Ag2 S as Determined by Neutron Diffraction

International Conference on Fast Ion Transport in Solids - Electrolytes and Electrodes, Lake Geneva, Wisconsin

R. J. Cava

May 1979

Preparation and Properties of YCr03 -Based Ceramics

Fourth International Meeting on Modern Ceramics Technologies - Energy and Ceramics, Faenza, Italy

T. Negas, L. P. Domingues, W. R. Hosier

May 1 979

Performance of U.S. Electrodes-Insulators Tested in the USSR

U-02, Phase III

18th Symposium on Engineering Aspects of MHD, Butte, Montana

J. L. Bates, J. L. Daniel, B. Rossing, J. W. Sadler, W. Hosier,

T. Negas

June 1979

Chemical Aspects of MHD Materials

International Colloquium on Refractory Oxides for High

Temperature Energy Sources, Toronto, Canada

T. Negas

July 1979

Identification of Materials by Single-Crystal X-ray Diffraction

FACSS-Vj Fifth Annual Meeting of the Federation of Analytical

Chemistry and Spectroscopy Societies.

Boston, MA

Presented by J. K. Stalick

J. K. Stalick, R. J. Boreni , and A. D. Mighell

October - November 1978

Powder Diffraction Standards and Reference Materials FACSS-V,

Fifth Annual Meeting of the Federation of Analytical Chemistry

and Spectroscopy Societies

Boston, Massachusetts

C. R. Hubbard

November 1978

375
The Elucidation of Molecular Structure and the Identification

of Crystalline Materials

Catholic University, Washington, D. C. A. D. Mighell

December 1978

NSRDS Workshop on On-Line Scientific Data Bases and Systems

Crystal Data Center: Status and Potential

National Bureau of Standards

Washington, D. C. A. D. Mighell and J. K. Stalick

January 1979

NBS Program for Fly Ash Characterization

ASME Meeting

United Engineering Center

New York, New York

C. R. Robbins

January 1979

Crystallography and High Pressure

ACA Meeting

Honolulu, Hawaii

S. Block

March 1979

Applications of the Diamond Cell in High Pressure Research

Department of Chemistry

Howard University

Washington, D. C. G. J. Piermarini

April 1979

High Pressure Studies of Liquids and Crystals

Cornell University, Ithaca, New York

S. Block

May 1979

Correlation of the Glass Transition and the Pressure Dependence of

Viscosity in Liquids

1979 - U. S. Army Symposium on Ultra-High Pressure Phenomena

Rensselaervi lie, New York

R. Munro, G. J. Piermarini, and S. Block

June 1979

377
Optical Microscopic and Electrical Resistance Studies of CuCl at

High Pressure

1979 - U. S. Army Symposium on Ultra-High Pressure Phenomena

Rensselaerville, New York

G. J. Piermarini and S. Block

June 1979

Standard Reference Materials for Quantitative Analysis and dSpacing Measurement

Symposium on Accuracy in Powder Diffraction

National Bureau of Standards

Washington, D.C.

C. R. Hubbard

June 1979

The Reliability of Powder Indexing Procedures

Symposium on Accuracy in Powder Diffraction

National Bureau of Standards

Washington, D.C.

A. D. Mighell and J. K. Stalick

June 1979

Stereochemical Disorder in Two Dopamine Analogs: 2-Ami notetral in

Hydrochloride and 2-Amino-6,7-dihydroxytetralin Hydrobromide.

ACA Meeting

Boston, Massachusetts

Presented by J. K. Stalick

J. K. Stalick, C. R. Hubbard, and A. D. Mighell

August 1979

Standard Reference Materials for Powder Diffraction

28th Annual Denver X-ray Conference

Denver, Colorado

C. R. Hubbard

August 1979

Application of an Energy Dispersive Detector to Crystallographic

Studies with the Diamond Anvil Pressure Cell

American Crystallographic Association

Summer Meeting

ACA Meeting

Boston, Massachusetts

Presented by F. A. Mauer

F. A. Mauer, S. Block, and G. J. Piermarini

August 1979

Chemical Identification and Characterization: The Role of the NBS

Crystal Data File

The American Chemical Society Symposium: Crystallographic Data

Bases for the Chemist

Presented by J. K. Stalick and A. D. Mighell

September 1979

378
New Bond-Delocalized Dianions. A Crystal Structure of 1,3-

(Dicyanomethylene) croconate Salt (CiiN 40 3 K2

* 2H2 0 ) American Chemical Society Meeting

Washington, D.C.

Presented by V. Himes, A. D. Mighell, C. R. Hubbard, A. J . Fatiadi

September 1979

Laser-Induced Fluorescence Line Narrowing of Eu 3 ~ in Lithium

Borate Glasses

International Luminescence Conference, Paris, France

J. Hegarty, W. M. Yen, M. J. Weber, D. H. Blackburn

July 1978

Standard Techniques for Measuring Window Absorption and Other

Efficiency Losses in Semiconductor X-ray Energy Spectrometers

Symposium on Energy Dispersive X-ray Spectrometry, NBS,

Gaithersburg, Maryland

F. J. Walter, R. Stone, D. H. Blackburn, P. Pella

Glass Standards and Glass Research at the National Bureau of

Standards

Battelle Research Institute, Columbus, Ohio

W. K. Haller

May 1979

Surface Deri vati zed Silica-Sol Particles as Imnunospecific

Markers for High Resolution Electron Microscopy

T ntprna f i nna 1 Pnnfarpnra nn "f hpm-i c + ry nf ^nUrl/l igin’H Tnfarfaroc " Cavtat, Yugoslavia

W. K. Haller

June 1979

The Melt Vapor Pressure and Glassy Film Program at the National

Bureau of Standards

Brockway Glass Company, 3rockway, Pennsylvania

D. M. Sanders

July 1979

Development of Fluorophosphate Optical Glasses

23rd International Symposium of the Society of Photo-Optical

Instrumentation Engineers, San Diego, California

W. K. Haller

August 1979

Properties of Crystalline Materials for Optics

SPIE, San Diego, California

A. Feldman

August 1979

Survey of Refractive Data on Materials for High-Power Ultraviolet

Laser Applications

SPIE, San Diego, California

A. Feldman

August 1979

379
Improper Ferroelectrics

University of Illinois (Chicago Circle)

M. I. Bell

May 1979

Eddy Currents in a Bar With a Crack

Workshop on Eddy Current NDE

General Electric, Co., Schenectady, New York

A. H. Kahn

February 1979

AC Magnetic Fields in the Vicinity of a Crack

ARPA/AF Review of Progress in NDE

San Diego, California

A. H. Kahn

July 1979

Method for Calculating Eddy Current Distribution in Cylindrical

Bars with a Crack

Symposium on Eddy Current Characterization of Materials

National Bureau of Standards, Gaithersburg, Maryland

A. H. Kahn

September 1979

Publications

Lattice Image Study of Crystal Structures of Mixed Oxides in the

Systems Rb2 0-Ta2 0 5 , Rb 2 0-Nb2 0 5 and K2 0-Ta2 0 5 With Composition

Ratios Near 1:3~ Part I. Structures of "11 L," "9 L," and "16 L"

K. Yagi and R. S. Roth

Acta Cryst. A34 765-773 (1978)

Lattice Image Study of Crystal Structures of Mixed Oxides in the

Systems Rb2 0-Ta2 0 5 , Rb 2 0-Nb2 0 5 and K2 0-Ta2 0 5 With Composition

Ratios Near 1:3. Part II. Various Intergrowth Phases and TwoDimensional Ordering of Pentavalent Ions

K. Yagi and R. S. Roth

Acta Cryst. A34 773-781 (1978)

Y-Deflection Modulated Secondary Electron Images in the

Evaluation of Ceramic Surface Finish

L. P. Cook, E. N. Farabaugh, and C. D. Olson

Symposium on Science of Ceramic Surface Finishing and

Machining II, NBS, November 1978

Crystal Structures of Some Niobium-Tantalum Oxides. Part VI.

The Structure of H-LiTasOg

G. D. Fallon, B. M. Gatehouse, and R. S. Roth

J. Solid State Chem. 2J_, 255-259 [1979)

~he Crystal Structure of the Cation-Disordered Phase

0

"

f o . 75

^9 .2 5 ) 4^1

5

P. M. Skarstad, R. S. Roth, C. R. Hubbard, and H. S. Parker

J. Solid State Chem. 29 [2] 0979)

380
Characterization of Modulated Structures in ABG 1+ Phases

R. J. Cava and R. S. Roth

' x Proceedings of Symposium on Modulated Structures, Honolulu, Hawaii

March 1979

Conductivity Mechanisms in the Superionic Phases of Agl and Ag2 S as Determined by Neutron Diffraction

R. J. Cava, F. Reidinger, and B. J. Wuensch

International Conference on Fast Ion Transport in Sol ids-Electrolytes

and Electrodes, Lake Geneva, Wisconsin, May 1979

Preparation and Properties of Yttrium Chromite Ceramics

T. Negas, W. R. Hosier, and L. P. Domingues

Proceedings Saint-Vincent Conference on Energy and Ceramics, Faenza,

Italy, May 1979

Performance of U.S. Electrodes-Insulators Tested in the USSR U-02

Phase III

J. L. Bates, J. L. Daniel, B. Rossing, J. W. Sadler, W. R. Hosier,

and T. Negas

18th Symposium on Engineering Aspects of MHD, Butte, Montana,

June 1979

Lead Alkali Apatites Without Hexad Anion: The Crystal Structure

of Pb8 K2 (P0 4 )s

M. Mathew. W. E. B rown. M. Au stin , and T. N eoas

J. Solid State Chemistry (In Press)

Phase Equilibria Research in Portions of the System K2 0-Mc0-

Fe 2 03 “Al o 03 “Si 02

R. S Roth

Symposium on Solid State Chemistry: A Contemporary Overview

(In Press)

Magnetic Properties and Hyperfine Interactions in the p‘" Phase

of Potassium Ferrite

V. P. Romanov, G. A. Candela, R. S. Roth, and L. J. Swartzendruber

J. Appl. Phys. (In Press)

Neutron Powder Diffraction Study of the Structures of CeTaQ4 , CeNb04 , and NdTa04

A. Santoro, M. Marezio, R. S. Roth, and D. B. Minor

Acta Cryst. (in press)

Thermal Stability of Long Range Order in Oxides

R. S. Roth

Progress in Solid State Chemistry (in press)

Neutron Powder Diffraction Study of Ta2 WC s A. Santoro, R. S. Roth, and D. 3. Minor

Acta Cryst. (in press)

281
Materials for Open Cycle MHO Generators

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

Book Series on Material Science, North Holland Publishing Co.

(in press)

Hybrid Temperature-Oxygen Fugacity Sensor

T. Negas, L. P. Domingues, T. Drzewiecki, and R. M. Phillippi

March 1979 (Patent Pending)

Development of Fluorophosphate Optical Glasses

J. T. Wenzel, D. H. Blackburn, W. K. Haller, S. Stokowski,

and M. J. Weber

Proceedings of the International Symposium on "Physical Properties

of Optical Materials," Society of Photo-Optical Instrumentation

Engineers, San Diego, California, Aug. 27-30, 1979.

Surface Deri vati zed Silica-Sol Particles as Immunospecific Markers

for High Resolution Electron Microscopy

W. K. Haller

Proceedings of the 5th International Conference on Chemistry of

Solid/Liquid Interfaces, Cavtat, Yugoslavia, June, 1979

Surface Conductivity of Glass at the Solid/Liquid Interface

J. Jednacak-Biscan, V. Mikac-Dadic, V. Pravdic, W. K. Haller

J. Colloid and Interface Science 70 [1] 18-28 (1979)

Laser- Induced Fluorescence Line Narrowing of Eu

3+

in Lithium

Borate Glasses

J. Hegarty, W. M. Yen, M. J. Weber, D. H. Blackburn

J. Luminescence 18/1 , 657-660 (1979)

Optical and Physical Parameters of Plexiglass 55 and Lexan

Roy M. Waxier, D. Horowitz, and A. Feldman

Applied Optics 18, 101-104 (1979)

Piezo-Optic Coefficients of Some Neodynium Doped Laser Glasses

and Single Crystals of CaF2 , BaF2 , and SrF2

R. M. Waxier, A. Feldman, and D. Horowitz

Proceedings of the Symposium on Laser Induced Damage in Optical

Materials: 1978, NBS Boulder, Colorado, Sept. 12-14, 1978

NBS Special Publication 541

382
Eddy Currents in a Conducting Cylinder with a Crack

R. D. Spal and A. H. Kahn

Journal of Applied Physics (accepted for Sept. 1979)

A Boundary Integral Equation Method for Calculating the Eddy

Current Distribution, etc.

Proceedings of the Symposium on Eddy Current Characterization

(NBS/ASTM - September 1979

A. H. Kahn and R. D. Spal (to be published)

Modulated Optical Spectroscopy of PLZT Ceramics

S. H. Shin, M. I. Bell, F. H. Poliak, and P. M. Raccah

Amer. Ceram. Soc. Bull. 57 769 (1978).

Direct Measurement of Pyroelectric Figures of Merit

of Proper and Improper Ferroelectrics

A. Shaulov, M. I. Bell, and W. A. Smith

J. Applied Physics (to be published)

Thermal and Dielectric Properties of LiKS0 4 and LiCsS0 4 M. Delfino, G. M. Loiacono, W. A. Smith, A. Shaulov, Y. H. Tsuo,

and M. I. Bel 1 J. Solid State Chemistry (to be published)

Electroreflectance of PZT Ceramics

S. H. Shin, F. H. Poliak, and M. I. Bell

J. of Ferroelectrics (to be published)

Improper Ferroelectrics for Pyroelectric Detection of Infrared

Radiation

Shaulov, W. A. Smith, G. M. Loiacono, M. I. Bell, and Y. H. Tsuo,

J. of Ferroelectrics (to be published)

One-Dimensional Ising with Generalized Molecular Field

G. J. Isfrate, A. Ballato, and M. I. Bell

J. Mag. and Mag. Mat. (to be published)

Dielectric, Pyroelectric, and Thermal Properties of LiNH 4 S0 4 and LiND4 S04

G.M. Loiacono, M. Delfino, W. A. Smith, M. I. Bell, A. Shaulov,

and Y. H. Tsuo

J. of Ferroelectrics (to be published).

Bistable Optical Systems Based on a Pockels Cell

A. Feldman

Opt. Lett. 4, 115 (1979).

383
The National Bureau of Standards Optical Measurements Program:

Refractive Index, Thermo-optic Constants, and Photoelastic

Constants

A. Feldman, M. J. Dodge, D. Horowitz, and R. M. Waxier

to be published in 10th Anniversary volume of the Laser Damage

Symposium (Academic Press).

Survey of Refractive Data on Materials for High-Power Ultraviolet

Laser Applications

A. Feldman, R. M. Waxier, and I. H. Malitson

Proceedings of the SPIE (to be published)

Properties of Crystalline Materials for Optics

A. Feldman and R. M. Waxier

Proceedings of SPIE (to be published)

3a, 6a-Dimethylglycouryl [3a,6a-Dihydro-3a, 6a-dimethyl imidazol

(4,5-d) imidazole 2,5(lH,6H)-dione]

V. L. Himes, C. R. Hubbard, A. D. Mighell, and A. J. Fatiadi

Acta Crystal lographica B34, 3102-3104 (1978)

S-Carboxymethyl -L-cystei ne

A. D. Mighell, C. R. Hubbard, J. A. Staffa, and C. Zervos

Acta Crystal lographica B35 , 1258-1262 (1979)

2-Ethoxy-l, 7,9-triethyl-7, 9-dihydro-lH-purine-6,8-dione; a Tetraethyl Derivative of Uric Acid

A. D. Mighell, C. R. Hubbard, and A. Cohen

Acta Crystal! ographica B35, 1280-1282 (1979)

Wall Effects in a Diamond-Anvil Falling-Sphere Viscometer

R. G. Munro, G. J. Piermarini, and S. Block

J. Appl . Phys. , May (1979)

Correlation of the Glass Transition and the Pressure Dependence

of Viscosity in Liquids

R. G. Munro, S. Block, and G. J. Piermarini

J. Appl. Phys., Sept. (1979)

Raman Spectroscopic Evidence for Conformation Deformation in the

High Pressure Phase of Polytetrafl uoroethylene

J. F. Rabolt, G. J. Piermarini, and S. Block

J. Chem. Phys. 69, 2872 (1978)

384
A Novel Bimetallic Sulfur Cluster. Crystal and Molecular Structure ^

of a Dimer of Bis[methyldiphenylphosphinesilver]tetrathiotungsten,

[(C6 H 5 ) 2 PCH3 ] 4 Ag4 W2 S 8

J. K. Stalick, A. R. Siedle, A. D. Mighell, and C. R. Hubbard

J. Am. Chem. Soc. 101, 2903 0979)

The Diamond Cell Stimulates High Pressure Research

S. Block and G. J. Piermarini

USP Fiz. Nauk. SSR 127, [4] April (1979)

(Translated and reprinted from Physics Today, September (1976))

Standard X-ray Diffraction Powder Patterns, Section 15, Data for

112 Substances 1 M. C. Morris, H. F. McMurdie, E. H. Evans, B. Paretzkin,

J. H. deGroot, B. S. Weeks, R. J. Newberry, C. R. Hubbard, and

S. J. Carmel

NBS Monograph 25, Section 15, October (1978)

j On a Parametrization for Solids Under Hydrostatic Pressures _i

R. G. Munro, G. J. Piermarini, and S. Block

Phys. Lett. A 66, 392 (1978)

A Preliminary Report on the Design and Results of the Second

Round Robin to Evaluate Search/Match Methods for Qualitative

Powder Diffractometry

C. R. Hubbard and R. Jenkins

Advances in X-Ray Analysis 22 (1979)

X-Ray Powder Diffraction Measurements in Reactive Atmospheres at

1000 °C and 7 MPa (1000 psig)

F. A. Mauer and C. R. Robbins

Advances in X-Ray Analysis 22, Plenum Press, New York (1979)

The Reliability of Powder Indexing Procedures

A. D. Mighell and J. K. Stalick

Proceedings on “Accuracy in Powder Diffraction" (In Press) (1979)

An Evaluation of the Performance of Materials and Components Used

in the Conoco Lignite Gasification Pilot Plant, C0 2 Acceptor

R. C. Dobbyn, H. M. Ondik, 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

U. S. Department of Energy Report (In Press) (1979)

Laboratory Examination, and Evaluation of the Gasifier Lining Used

in the Conoco Lignite Gasification Pilot Plant

W. S. Brower, R. C. Dobbyn, and C. R. Robbins

DoE Newsletter, “Materials and Components in Fossil Energy

Applications" (In Press) (1979)

Factors Affecting the Durability of Adobe Structures

P. W. Brown, C. R. Robbins, and J. Clifton

Studies in Conservation (In Press) (1979)

385
Synthesis, Crystal and Molecular Structure of [(C 7 H7 ) 3 P] 4 Cu4W2 02 S 6 , a dimer of Bi s(tri (p-toly) phosphine copper) oxotrithiotungsten

R. Doherty, C. R. Hubbard, A. D. Mighell, A. R. Siedle, and

J. Stewart

Inorganic Chemistry (In Press) (1979)

Optical Microscopic X-Ray Diffraction, and Electrical Resistance

Studies of CuCl at High Pressure

G. J. Piermarini, F. A. Mauer, S. Block, A. Jayaraman,

T. H. Geballe, and G. W. Hull

Solid State Communications (In Press) (1979)

(3-Chloro-2-oxo-5-Nitrophinyl ) (2-Chlorophenyl ) iodonium, inner

salt

C. R. Hubbard, A. D. Mighell, V. L. Himes, and S. W. Page

Acta Crystal lographica (In Press) (1979)

Symmetry Determination

A. D. Mighell and J. Rodgers

Acta Crystal lographica (In Press) (1979)

Platinum thiotungsten Compounds: Crystal and Molecular Structure

of Bis(trielhylphosphine) platinum tetrathiotungsten

A. Siedle, C. Hubbard, A. Mighell, R. Doherty, and J. Stewart

J. Inorganic Chemistry (In Press) (1979)

Advances in High Pressure Research with the Diamond Anvil Cell

R. G. Munro

LaRecherche (In Press) (1979)

Dixanthyl urea (N ,

N

1 -di-9H-Xanthen-9-Yl urea)

C. R. Hubbard, A. D. Mighell, and A. Fatiadi

Acta Crystal! ographica (In Press) (1979)

Structure of (3-Chloro-2-oxo-5-nitrophenyl )(2' -chi orophenylI.) Iodonium, Inner Salt

S. W. Page, E. P. Mazzola, A. D. Mighell, V. L. Himes, and

C. R. Hubbard

JACS (In Press) (1979)

Standard Reference Materials for Quantitative Analysis and

d-spacing Measurement

C. R. Hubbard

Proceedings on "Accuracy in Powder Diffraction" (In Press) (1979)

386
Special Reports

Dark Streaks Produced by Electrical Conduction in MgO

T. Negas and W. P. Unruh

Annual Report to Oak Ridge National Laboratory,

Oak Ridge, Tennessee

Laboratory Examination and Evaluation of the Gasifier Lining

Used in the Conoco Lignite Gasification Pilot Plant

W. S. Brower, R. C. Dobbyn, and C. R. Robbins

DoE Newsletter - Materials and Components in Fossil Energy

Applications, 1979

An Evaluation of the Performance of Materials and Components

Used in the Conoco Lignite Gasification Pilot Plant, C02

Acceptor

R. C. Dobbyn, H. M. Ondik, 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

U. S. Department of Energy Report (Submitted to DoE)

A Thermochemical Study of Corrosive Reactions in Oxide Materials

H. S. Parker, R. S. Roth, C. D. Olson, and E. R. Plante

in NBS: Properties of Electronic Materials, J. R. Manning, ed.

,

NBSIR 79-1767, pp. 82-102 (1979)

S Tag ' CfiSF&ctIM zatTon

~ M ~ TM ^ “““

W. S. Brower, J. L. Waring, and D. H. Blackburn

in Materials Research for the Clean Utilization of Coal,

prepared for DoE, October 1978, December 1978, March 1979,

June 1979

Optical Materials Characterization

A. Feldman, D. Horowitz, R. M. Waxier, and M. J. Dodge

NBS Technical Note 993 (USGPO Stock No. 003-003-02031-1,

Washington, D. C. , 1979)

Piezo-optical Coefficients of Some Neodymium Doped Laser

Glasses and Single Crystals of CaF 2 , BaF2 , and SrF2 , in

Laser Induced Damage in Optical Materials : 1978 , NBS Special

Publication, 541, Eds., A. J. Glass and A. H. Guenther

(USGPO, Washington: 1979) pp. 50.

Refractive Index of Strontium Fluoride

M. J. Dodge

Laser Induced Damage in Optical Materials : 1978, Special

Publication 541, (December 1978), p. 55.

Materials for Fuel Cells

L. H. Bennett, M. I. Cohen, A. L. Dragoo, A. D. Franklin,

and A. J. McAlister

NBSIR 79-Annual Report January 1978 - December 1978

Issued in May 1979 (in press)

387
Sponsored Conferences

Laser Glass Conference

National 3ureau of Standards, Washington, D.C.

August 2-3, 1979

Accuracy in Powder Diffraction

Symposium sponsored by NBS, NRC, IUC

Washington, D.C.

June 11-15, 1979

Technical ana Professional Committee Participation and Leadership

International Commission Glass (U.S. Representative)

W. K. Haller

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. 1C Haller

ASTM Committee C-14 on Glass and Glass Products

W. K. Haller

AST^ Subconaittee C-14. 03 on Chemical Properties of Glass

W. K. Haller

ASt^ Committee C-14 on Glass and Glass Products

M. J. Cellarosi

Vice Chairman

AS7M Subcommittee C-14. 04 on Physical and Mechanical Properties of

G ass

M. Cellarosi

ASTM Suocommittee C-14. 01 on Nomenclature of Glass and Glass

Products

M. Cellarosi

Chai rman

AS~M Subcommittee E-38 on Resource Recovery

M. J. Cellarosi

388
ASTM Subcommittee E-44 on Solar Heating and Cooling Applications

M. J. Cellarosi

ASTM Subcommittee C-14. 08 on Flat Glass

M. J. Cellarosi

ANSI Committee F-l on Hybrid Electronics

M. J. Cellarosi

JEDEC (Joint Electron Devices Engineering Councils)

M. J. Cellarosi

EIA (Electronic Industries Assoc.) Committee on X-ray and Implosion

TV Standards

M. J. Cellarosi

ASTM Committee C-14 on Glass and Glass Products

D. J. Cronin

ASTM Subcommittee C-14. 04 on Physical and Mechanical Properties

of Glass

D. J. Cronin

ANSI Committee Z- 25. 1 on Safety Glazing of Motor Vehicles

D. J. Cronin

ANSI Committee Z-97 on Architectural Safety Glazi-ng

D. J. Cronin

ASTM Sbucommittee FI. 02, Electronics Committee, Subcommittee

and Lasers

A. Feldman, Editor

Standard Reference Materials

SRM 470 on Mineral Glasses for Microanalysis

D. H. Blackburn in collaboration with C. E. Fiori and

R. B. Marinenko

ASTM C-21 on Ceramic Whitewares and Related Products

H. S. Parker

ASTM C-8 on Refractories

W. S. Brower

Committee on Publications of the American Ceramic Society

Subcommittee on "Phase Diagrams for Ceramists"

R. S. Roth

Panel member on Review of Montana Tech - Montana State Research

for MHO, October 1978

T. Negas

3S9
Consulting and Advisory Data Centers

Phase Diagrams for Ceramists Data Center

R. S. Roth, L. P. Cook, T. Negas, and G. W. Cleek

Crystal Data Center (OSRD)

A. D. Mighell, J. K. Stalick, R. Boreni

JCPDS - Ind. Centre for Diffraction Data

C. R. Hubbard, S. Block, and A. D. Mighell

Materials Information and Data Center (Fossil Energy)

H. M. Ondik, R. C. Dobbyn, A. Perloff, T. A. Hahn, and

W. A. Willard

Consulting Services

Considerable time of Section members was spent in replying to

inquiries from other government agencies, industry, research laboratories, universities, small businesses, and individuals. Some examples

from this year are:

Department of the Treasury, Forensic Science Branch and Indiana

State Police Lab needed help in criminal cases involving the

matching of glass fragments against possible source objects.

Architect of the Capitol . Multiple safety glazing had been installed

in some buildings under his jurisdiction. Was concerned about strange

optical phenomena and requested in-si tu tests for conformance with safety

requirements.

New York-New Jersey Port Authority . Spontaneous breakage of ten

large tempered windows. Requests information about possible cause and

evidence of contractor negligence.

National Security Agency . Electrical conductive windows.

Department of Justice, Tax Division . Need technical help in tax

cases against glass manufacturers. Try to establish if tin (float glass

process bath) and platinum (fiber glass manufacturer) are "everlasting"

or "depreciable assets."

Idaho Falls Nuclear Waste Disposal Facility . Use slags as binder to

solidify low-level transuranic waste. Interested in slag properties

(viscosity, etc.)

390
Congressional Sub-Committee on Energy and Power . Wanted history of

previous efforts to recover helium from natural gas using glass-membranes

for separation.

Federal Trade Commission; Bureau of Customs; Dept, of Justice

(Antitrust Div. ). Definitions for certain glass products, manufacturing

processes' uses.

International Cooperation

4th Joint Meeting of the US/USSR Working Group on Metrology,

Moscow, USSR, June 25 - July 5, 1979. The delegation of 5 NBS

staff members, lead by Dr. A. 0. McCoubrey, included H. P. R. Frederikse

(Materials Standards and Testing). The group visited the headquarters

of Gosstandard in Moscow and regional laboratories in Leningrad, Yerevan

and Irkutsk.

391
REACTOR RADIATION DIVISION
3S3
REACTOR RADIATION DIVISION

Robert S. Carter, Chief

Tawfik M. Raby, Deputy Chief

E. C. Maxwell, Administrative Officer

L. L. Sprecher, Secretary

The Reactor Radiation Division 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 FY 79 are indicated in the tables

below.

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

RRD Permanent Scientists

Non-RRD Participants

Other NBS

Other Agency

University

Industrial

Total Non-RRD

No. of Personnel

FY 79

11

18

41

29

11

99

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.

394
Table 2. Independent Programs

No. of Personnel

FY 79

Other NBS 37

Other Agencies 23

Universities 20

Total 80

These tables demonstrate the extensive utilization of the NBS

reactor by scientists and engineers from outside the Division. They

come from 18 NBS Divisions and offices, 27 federal agencies, industrial

and national laboratories, and more than 24 universities.

Many of the other agency and university collaborators have worked

with us regularly for many years. Five of them (2 from the Navy and 3

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 em- brittlement, etc. Major independent (non-collaborative) 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 incude the FBI, FDA, U.S. Geological Survey, the Smithsonian Institute, Treasury Department (ATF),

and the University of Maryland. Programs range from analysis of criminal

artifacts to the measurement of pollutants in the environment.

Upgrading of the reactor to 20 MW is progressing. A contract for

the additional cooling tower should be let by the end of September or early October. The design of the modifications to the process piping

has been essentially completed except for that part which depends on details of the cooling tower which has not yet been selected. The heat

transfer calculations have been completed confirming that the existing

pumps can provide adequate flow when equipped with larger motors and

impellers. The writing of the Safety Analysis Report is continuing.

The fabrication of new fuel elements for the NBSR is progressing

smoothly. Texas Instruments is expected to deliver the first of our new elements in December 1979. This will assure us of continuity in our

fuel element supply. Our present supply would have run out in January

or February of 1980.

During the week of August 6-10, a serious mechanical problem

developed in one of our four shim arms that control the reactor. The

arm appeared to stick at certain angles. The reactor will be shut down

until the shim arm is fixed. This will probably require removing it

from the reactor vessel and working on it under water. A minimum of a two-month shutdown is anticipated.

395
It is not possible in this overview to summarize all the activities

of the many outside groups that use the reactor. These can be found in

the "Summary of Activities, July 1978- June 1979. 1,1 Some examples,

however, will be given here to illustrate the broad scope of these

programs that do not involve scientific collaboration with the Reactor

Radiation Division. The ENDF/B V file is a basic file of neutron cross section data used in reactor physics calculations. Fundamental un- certainties in the capture cross section of U-238 were uncovered in the

preparation of these files. NBS was called on by DoE to look into the

problem. Careful measurements of the U-238 capture to U-235 fission

cross section ratio made by the Center for Radiation Research in the

Intermediate-energy Standard Neutron Field (ISNF) maintained at the

reactor were able to resolve this uncertainty. Neutron activation

analysis was used to determine the thickness of the palladium protective

layer important to the successful operation of solar cells in communication satellites. The FDA analyzed oats from a box car load that was suspected of having killed many cattle because of impurities absorbed by

the oats from the box car which had not been properly cleaned. They

were able to show that the suspected contaminate, NaSiF6 was in fact in

the oats. The Naval Research Laboratory was able to demonstrate the

efficiency of a new "gold-toning" neutron activation process for en- hancing very weak images on photographic film of interest to intelligence

and space agencies. The University of Maryland-NBS prompt q-ray trace

analysis facility has been actively used and has demonstrated its

potential for the characterization of Standard Reference Materials. The

work of the FBI, the Alcohol, Firearms, and Tobacco Division of the

Treasury Department, the Geological Survey, and many other smaller users continues unabated.

The scientific work of the Reactor Radiation Division and its

collaborators are summarized later in this report and details 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.

The Division competence initiative in Small Angle Neutron Scattering

(SANS) has started. The conceptual design and a large part of the

detailed design of a state-of-the-art facility has been completed and

many components are currently being fabricated and some installation has

begun. A small (20 cm x 20 cm) and a large (64 cm by 64 cm) area

detector with 0.5 cm resolution have been contracted for with delivery

expected early next spring. By the end of this fiscal year, two new scientists will have been hired to work on the program. (One has been

working on the program since its inception.) In addition, a visiting

scientist is studying the application of SANS to polymers. Considerable

outside interest in the use of the new facilities has already been

expressed by several outside groups.

i Prel i mi nary copies will be made available to Panel members prior to the

meeting.

396
Other developments include the integration of a new super minicomputer into the neutron spectrometer network providing high-speed

calculational capability as well as enhanced on-line manipulation of

experimental data. The potential of neutron scattering as a probe of

surface molecules of interest in catalytic reactions has been demonstrated.

Neutron vibrational spectroscopy has been used to examine the bonding of

hydrogen in transition metals at very low concentration and in a study

of the structure of prototype metallic glasses. A Greens function

random phase approximation theory has been developed which shows excellent

agreement with experimental results on Fe and Co rare-earth compounds

and explains both the excited state spin waves and spin reorientation

effects. The use of neutron induced autoradiography is being developed

in collaboration with the National Gallery of Art and the Smithsonian

Institution for the authentication of valuable paintings. These and

other highlights will be discussed more fully in the Task Reports in the

next section.

The DoD program for residual stress studies has failed to develop

but there is still a possibility for some work in this area. The

scientist to work on the application of neutron tomography to nuclear

safeguards has been hired and work is progressing in this area. We are looking forward to increased collaboration with the surface science

group in the Surface Science Division. They were one of the four groups

within NML to receive a share of the competence building fund made

available to NBS by Congress. We also anticipate an increased collaboration

with the Thermophysics Division in their study of mixed liquids and

liquid metals, and expanded collaboration with the Fracture and Deformation Division in the development of neutron methods for the microscopic investigation of hydrogen in embrittled metals. During the

coming year, we anticipate hiring a material scientist to develop

applications of small -angle scattering to problems in materials science

and work closely with other materials scientists in the Center.

REACTOR OPERATIONS AND SERVICES

The NBSR continued its leadership as one of the best utilized

research reactors in the country with 25 simultaneously operable facilities surpassing that of any other major facility. Operated roundthe-clock by the smallest staff of any comparable reactor, it again

produced an outstanding operating record. It supports many entensive

and diverse programs carried out by more than 150 scientists and engineers

from within and outside NBS. These programs range from the development

of standard reference materials, neutron standards and dosimetry, trace

analysis of foods and artifacts, the development of energy resources,

and the use of neutron radiography as an NDE tool for the determination

of the structure and properties of technologically important materials.

In all, 18 NBS Divisions and offices, 27 federal agencies, industrial

and national laboratories, and more than 24 universities depend on the

NBS reactor for vital programs.

397
The upgrade of the reactor power to 20 MW is progressing. The

higher power will greatly enhance reactor utilization and versatility.

Arrangements for the long-term supply of nuclear fuel have been completed

through use of Department of Energy facilities and contractors, and

delivery should commence by December 1979.

Technical Activity

Reactor Operations

T. M. Raby and J. F. Torrence

All aspects of reactor operations continued to be excellent until

the middle of August when the reactor had to be shut down because of

shim arm trouble. The shutdown is anticipated to last as least two

months. Once again, outstanding on-line performance, reactor utilization and fuel efficiency were achieved until the forced shutdown. A

summary of overall statistics is presented in the following table for

the period July 1, 1978-June 30, 1979.

NBSR OPERATING SUMMARY FY 78

No. of days at 10 MW 280

On-line time at 10 MW 77%

Average U-235 burnup 52%

No. of Irradiations 2040

Hours of Irradiations 3020

Hours per Irradiation 1.5

Irradiation Services

N. A. Bickford and J. H. Ring

Again tens of thousands of samples were irradiated involving many

important and diverse programs. These include trace analysis of foods,

drugs, and environmental samples, forensic investigation, development of

energy resources and minerals, and the analysis of archaeological treasures

and moon rock samples. In addition, over half of the standard

reference materials issued by the Bureau have been characterized using

the reactor. The work in these areas at the NBSR surpasses that of any

other research reactor in the U.S.

398
Many important new programs have been initiated. They include: the

establishment of a national Environmental Sample Bank which will provide

real-time monitoring data for pollutant trend evaluation as well as allow for more precise measurements in the future; the development of

state-of-the-art measurement techniques and standards for nuclear material

safeguards; image enhancement of underdeveloped photographic

film; and finally the analysis of waste materials being fed to animals

for their toxic effect on the food chain.

Engineering Services

J. H. Nick! as and R. J. Conway

Most of the Engineering Services effort outside of routine main- ' tenance and surveillance has been directed toward the procurement of new

fuel and the 20 MW upgrade.

All the engineering and specification questions have been resolved

on the fuel element manufacturing. Production is starting and the first

elements should be delivered in December 1979.

The heat transfer calculations have been completed. These have

been combined with careful flow measurements on the primary system and

confirmed that the present pumps do not have to be replaced. Replacement would have entailed much more extensive primary piping modifications

than will be required now. New motors and larger impellers which will

provide the necessary flow are now on order.

The design of the modifications to the secondary cooling system has

been completed except for some details which cannot be finalized until

the cooling tower choice is finalized. Some of the piping and other

components have been delivered and others are on order. Certain piping

modifications will be done during September which will expedite the

major changes to be made later.

The cooling tower "Request for Bids" has been sent out and a contract should be let the end of September or early October. The bids

include several options in an attempt to get the most effective tower we

can afford.

The last two months of the fiscal year were, of course, devoted to

repairing the facility shim arm so that the reactor could be put back in

operation as soon as possible.

NEUTRON SCATTERING CHARACTERIZATION OF MATERIALS FOR AOVANCED TECHNOLOGIES

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 of technological applications.

Current areas of emphasis include hydrogen in metals, new magnetic and

glassy materials, and molecular solids. The neutron inelastic, quasi399
elastic, and magnetic scattering techniques applied provide unique

information, e.g. , on phase transformations, interatom bonds, electronic

structure, sublattice magnetization, hydrogen diffusion, and molecular

and crystal dynamics. The members of this task (and the following task)

are also responsible for establishing and maintaining a center of excellence for neutron scattering and radiographic measurements including a computer-controlled network of 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 inhouse guest workers from Army Materials, NRL, NSWC, 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 (ANL,

ORNL) and universities (University of Maryland, University of Houston,

University of Saarlande). In addition, staff scientists are exploring

with other Divisions and Centers at NBS development of neutron scattering

methods for: (1) surface analysis of chemical products and reactions on industrial catalysts; and (2) ultrasensitive microscopic analysis of

hydrogen in metals.

New plans for the coming year include: (1) an expanded effort with

the Fracture and Deformation Division on the development of neutron

scattering for the unique microscopic study of hydrogen in embrittled

metals; (2) initiating research in collaboration with the Thermophysics

Division and the University of Wisconsin on the structure and dynamics

of liquid metals and fluid mixtures; and (3) a new research effort in

the neutron characterization of rapidly quenched amorphous rare-earth

glasses with scientists from Xerox.

Technical Activity

Microscopic Properties of Hydrogen in Metals and Molecular Materials

J. M. Rowe, J. J. Rush, S. F. Trevino,* and A. Magerl*

Examples of activities and accomplishments during the past year:

o Completed first neutron scattering measurements of low-level hydrogen

dynamics in transition metals in the presence of trapping interstitial impurities.

o Completed detailed neutron inelastic scattering investigation of a novel phase transition in mixed alkali halide-alkali cyanide crystals

and derived theory of dipole glasses to explain results.

o Probed hydrogen vibrations and interstitial sites in prototype

metallic glasses and polycrystals by high energy neutron scattering

spectroscopy.

400
o Completed study of chemisorbed molecular reaction products on Raney

nickel using neutron vibrational spectroscopy as a test of neutron

scattering to probe chemical reaction mechanisms on fine-particle

industrial catalysts.

o Completed first stage of computer modelling investigation of shock

wave propagation in condensed phases of molecules as part of a project to study the molecular basis of chemical instabilities

initiated by shockwaves.

o Finished design and began construction of high-intensity neutron

analyzer for surface spectroscopy and hydrogen in metals.

Microscopic Properties of Magnetic and Amorphous Materials

J. J. Rhyne, R. C. Casella, J. Lynn,* H. Alperin,* N. Koon,* and

K. Hardman

Example of activities and accomplishments during the past year.

o Our inelastic scattering studies of the Laves phase rare earth

compounds which are prototype two-component magnetic systems have

been expanded to include an examination of crystal field and ex- change interactions in rare earth cobalt compounds as well as a further investigation of excited state spin wave excitation in iron

o A Greens function random phase approximation (RPA) computer model

including both exchange and crystal field contributions has been

developed to analyze magnetic inelastic scattering data on rare

earth systems.

o The effect of hydride formation on the magnetic spin ordering of

several rare earth compounds has been examined and evidence has

been obtained of the formation of a pseudo "spin-glass" state

without true long range order on introduction of hydrogen into

these initially strongly-coupled conventional ferri magnetic compounds. A definitive crystallographic analysis of the site occupancy

of the hydrogen (or deuterium) is also nearing completion.

o A thorough study has been completed of the crystal fields in a number of chevrel -phase compounds which show co-existent phenomena

of superconductivity and magnetic ordering.

o A study of the critical point properties of a commercial ribbon

amorphous alloy has been performed using small angle scattering

techniques. In addition, the spin dynamics of the same alloys have

been examined at several temperatures.

o A study has been initiated of spin waves in Rb MnCl 3 , a ferromagnet

with alternating strong and weak exchange couplings.

401
0 A detailed comparison of the magnetic small angle scattering observed in amorphous rare earth alloys, amorphous transition metal

alloys, and conventional ferromagnets has been initiated in an effort to establish the role of random magnetic anisotropy in

forming and affecting the micro-domain structure of these materials.

o The sub- task leader was chairman of the Advisory Committee to the

International Conference on Magnetism and Magnetic Materials.

NEUTRON DIFFRACTION AND RADIOGRAPHIC METHODS FOR MATERIALS UTILIZATION

AND DURABILITY

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

the best U.S. 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) precise structure analysis essential for effective use of materials (e.g,. in batteries and construction materials);

(2) nondestructive reference methods for residual stress and texture

affecting metal product performance, for improved quality assurance,

e.g., in pacemaker batteries and composites, and for microstructure

analysis of materials in extreme environments; and (3) neutron radiography and beams 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 Building Technology (cement structure), Center for Thermodynamics and Surface Science (fluid properties),

and with three CMS Divisions (materials structure and durability). This

task also directly serves the Office of Nondestructive Evaluation and

Nuclear Safeguards. Outside interactions and cooperative research with

groups needing advanced neutron methods include NIH, NRL, Army Materials,

Navy, FDA, Goddard, Smithsonian, Allied Chem. , Xerox, Army, and universities

on projects ranging from corrosion detection to the structure of proteins.

New plans for the coming year include: (1) cooperative research

with industrial scientists on the use of high-resolution neutron diffraction as a probe of structure and chemically active sites in zeolyte

catalysts and in the study of microscopic transport mechanisms in prototype ionic conductors; (2) improved methods for measuring and interpreting

modulated structures in materials such as defect-oxide ceramics; and (3)

the development of state-of-the art instrumentation and scientific

applications for small angle neutron scattering.

402
0

0

0

0

0

0

0

Technical Activity

Neutron Diffraction Methods and Applications

E. Prince, A. Santoro, B. Mozer, H. Prask,* S. Choi,* and

A. Wlodawer

Examples of activities and accomplishments during the past year:

In our efforts to advance the method and application of high

resolution neutron-diffraction-profile analysis, we have developed

new approaches for constrained refinement (thermal motion effects)

and background subtraction in the profile analysis procedures.

Initiated several new applications of neutron profile analysis,

e.g. , in the probing of active sites in zeolyte catalysts.

Completed a theoretical investigation of absorption corrections for

Weissenberg geometry diffractometers, such as our recently developed

"flat-cone" neutron diffractometer. The formulas derived will be

useful for a new class of instruments employing area detectors.

Further refined the method and applications of nondestructive,

depth-sensitive neutron diffraction measurements of grain orientation profiles in alloy products subjected to different treatments

during fabrication.

As part of the NBS-NIH project on biomaterial structures, the

structure of the digestive enzyme ribonuclease was refined based on x-ray data to 2.5 A resolution, and a preliminary refinement based

on our neutron diffraction data was initiated.

First results have been completed in a neutron study by NBS, NIH,

and the University of Arizona scientists on the structure of highdensity lipoproteins.

Radiographic Methods and Standards

D. A. Garrett, Y. T. Cheng, and M. Ganowski

Examples of activities and accomplishments during the past year:

In collaboration with the Fracture Mechanics Division, initial

attempts have been made to macroscopical ly visualize hydrogen

migration in steel using conventional neutron radiographic methods.

These studies are continuing utilizing cold neutrons in an attempt

to increase measurement sensitivity.

403
0 Work has been initiated to accurately characterize neutron radiographic beam systems. Initial results on the measurements of the

L/D ratio utilizing one proposed method has yielded results in the

neighborhood of 10 to 30 percent higher than would be indicated by

geometrical measurements. The physics of this phenomenon is under

investigation.

o The conceptual design of the vertical resonance neutron system has

been completed. This system will be employed for both resonance

neutron radiography and tomography. Fabrication is pending approval

of the NBSR Hazards Evaluation Committee.

o Software for the resonance neutron tomography and image reconstruction of containers utilized in reactor fuel processing plants has

been obtained and modified. Initial simulation experiments have

proved to be successful. These experiments have indicated that

different algorithms must be employed for low and high contrast

material in the containments.

o Work has been sponsored by the National Gallery of Art and the

Smithsonian Institution to determine the feasibility of employing

neutron induced autoradiography and high resolution gamma- ray

spectroscopy for the authentication and attribution of valuable

paintings. The preliminary results are quite encouraging and

indicate a very important role for this method in the future.

o Experiments continue to characterize the electrolyte of cardiac

pacemaker batteries during rundown. Neutron radiography and

x-radiography exhibit complementary results. Three-dimensional

neutron radiography conducted during the past year has indicated

that void formation is indeed taking place during the rundown

process.

Advanced Neutron Methods: Small -Angle Neutron Scattering

C. Glinka, and A. Cinquepalma

The Reactor Division has been granted support under the NBS Competence Building Program to develop new and advanced instrumentation and

scientific applications in neutron scattering from materials. The

original focus of the competence building activity is small -angle neu- tron 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.

Much of the engineering design work has been completed for a new,

state-of-the art, SANS facility. The fabrication and procurement of

various components of the instrument are well underway and installation

is expected to begin in September 1979. Cooperative research activities

have already been initiated with NRL, NIH, NSWC, and several universities.

404
The new SANS instrument will utilize long wavelength neutrons (5 to

10 A) and “pinhole" collimation along an evacuated eight meter flight

path to reach wave vectors ranging from 0.002 to 0.2 A 1. Measurements

in this region serve to probe structure in the size domain from roughly

10 to 3000 A. A unique feature of the new instrument will be a geometrically focused collimation system which will effectively utilize the

entire source flux while maintaining the stringent collimation conditions

necessary for measurements at small scattering angles. The data collection rate with the new instrument will be greatly enhanced over what is

presently available by use of a newly developed type of position-sensitive

area detector. The sensitive area of the detector is 65 cm x 65 cm

(with a 5 mm resolution element) and will simultaneously record data

over the entire small -angle region. The data collection will be controlled by a dedicated minicomputer which will in turn be linked to

larger computers for display and analysis of the data.

The construction of the instrument, the testing and calibration of

the detector, and the development of instrument software will proceed in

parallel over the next year with the facility becoming operational

during 1980.

^Long-term, full-time guest worker

Other Division Activities

Invited Talks

“Application of Neutron Scattering to Biology"

University of Alabama, Birmingham, Alabama

A. Wlodawer

October 1978

“Science Fact Versus Science Fiction-A Strange Story of Polywatar"

University of Alabama, Birmingham, Alabama

A. Wlodawer

October 1978

“Dynamics of Molecular Reorientations"

McMaster University, Ontario, Canada

J. M. Rowe

November 1978

“Hydrogen in Metals"

University of Virginia, Charlottesville, Virginia

J. M. Rowe

November 1978

“Neutron Scattering Studies of Macromolecules"

University of California at Lost Angeles, Los Angeles, California

Molecular Biology Institute

A. Wlodawer

November 1978

405
“Neutron Inelastic Scattering Spectroscopy"

Argonne National Laboratory, Argonne, Illinois

NSF Workshop on “Present Needs and Future Trends in Neutron Crystal lograpti and Spectroscopy"

J. J. Rush, S. H. Chen

November 1978

“Science Versus Science Fiction: The Strange Story of Polywater"

National Institutes of Health, Bethesda, Maryland

A. Wlodawer

February 1979

“An Observation of Quantum Mechanical Tunneling and Classical

Reorientation in Solid Ni tromethane.

NBS, Thermal Heat Division

S. Trevino

March 1979

“Sizing Pipeline Girth Weld from Field Radiographs"

ANS Spring Conference/Display, San Diego, California

D. A. Garrett

April 1979

“The Observation of Electrolyte Phenomena in Lithium Iodide Pace'

maker Batteries with Neutron Radiographic Interrogation"

ANS Spring Conference/Display, San Diego, California

D. A. Garrett

April 1979

"Structure of High Density Lipoprotein Recombinants Studied by

Neutron Low-Angle Scattering"

Duke University, Durham, North Carolina

8th Annual Souteastern Macromolecular Structure Meeting

A. Wlodawer

May 1979

"Studies of the Structure of Ribonuclease-A by X-ray and Neutron

Single-Crystal Diffraction"

National Institutes of Health, Bethesda, Maryland

NIAMDD Scientific Counselors Meeting

A. Wlodawer

June 1979

"Studies of the Reorientations of the Methyl Groups of Solid

Nitromethane"

NSWC, White Oak, Maryland

Energetic Materials Division

S. Trevino

June 1979

406
"Dynamics of A1 kal iCyanide"

Argonne National Laboratory, Argonne, Illinois

J. M. Rowe

June 1979

"Amorphous YFe2 —A Concentrated Spin Glass"

Joint Intermag MMM Conference

New York, New York

D. W. Forrester, N. C. Koon, J. H. Schelleng, and J. J. Rhyne

July 1979

"Critical Magnetic Neutron Scattering from Cobalt"

University of Maryland, College Park, Maryland

C. Glinka

August 1979

"Use of Contraints in Crystal Structure Refinement"

Boston University- American Crystallographic Association, Boston,

Massachusetts

E. Prince

August 1979

"Studies of Ribonuclease-A by X-ray and Neutron Diffraction"

Boston University-American Crystallographic Association, Boston,

Massachusetts

A. Wlodawer

August 1979

Publications and Patents

Magnetic Relaxation Phenomena in Dy-Sc Alloys

R. Abbundi , J. J. Rhyne, D. M. Sweger, and R. Segnan

Physical Review B, 18 3313 (1978).

Magnetization and Neutron Scattering Measurements on Amorphous

NdFe2 H. A. Alperin, W. R. Gillomor, S. J. Pickart, and J. J. Rhyne

J. Appl . Phys 50 1958 (1979).

Small Angle Neutron Scattering from Rare Earth Iron Alloys

H. A. Alperin, J. Pickart, J. J. Rhyne

J. Applied Crystallography 11 648-49 1978.

Production of Ultracold Neutrons Using Doplar-Shi fted Bragg

Scattering and an Intense Pulse Neutron Spallation Source

T. W. Dombeck, J. W. Lynn, S. A. Werner, T. Burn, J. Carpenter

V. Krohn, R. Ringo

Nuclear Instruments and Methods (in press).

Neutron Scattering from Coherent Admixtures of Phonons with

Libronic Excitations of Dictomic Imprintion

R. C. Casella

Phys. Rev. B (submitted).

407
Nondestructive Investigation of Texture by Neutron Diffraction

C. S. Choi, H. J. Prask, and S. F. Trevino

J. Appl . Cryst. , (in press).

1-, 2-, 3-Triaminoguanidinium Nitrate by Neutron Diffraction

C. S. Choi, E. Prince

Acta Cryst. B35, 761-3 (1979).

Effect of Hydrogen on Sub lattice Magnetization of Laves Phase Rare

Earth Iron Compounds

G. E. Fish, J. J. Rhyne, S. G. Sankar, W. E. Wallace

J. Appl. Phys. 50, 2003 (1979).

Neutron Scattering Studies of Hydrides of the Laves Phase Rare

Earth Compounds RFe2

G. E. Fish, J. J. Rhyne, T. Burn, P. J. Viccaro, D. Niarchos,

B. D. Dunlap, G. K. Shenoy, S. G. Sankar, W. E. Wallace

The Rare Earths in Modern Science and Technology, Vol. 2, Plenum

Press, (in press).

Spin-Glass and Magnetic Blocking Transitions in Amorphous YFe2 D. W. Forrester, N. C. Koon, J. H. Schelling, J. J. Rhyne

Solid State Commun. , 30 177-180 (1979).

ASTM Recommended Practive for Thermal Neutron Radiography of

Materials

D. A. Garrett

American Society for Testing and Materials (submitted for ballot).

Neutron Crystal -Field Spectroscopy of CeD

C. J. Glinka, J. M. Rowe, G. G. Lubowitz, A. Maeland

J. Phys. C (in press).

Excited State Spin Waves in ErFe2

N. C. Koon, J. J. Rhyne

Solid State Commun. Vol. 26, pp. 537-540 (1978).

RPA Theory of Magnetic Excitations in Rare Earth-Transition Metal

Compounds: Application to ErCo2 and ErFe2

N. C. Koon, J. J. Rhyne

Inti. Journal of Magnetism (to be published).

Magnetic Correlations and Crystal Field Levels in the Superconductor (Ceo . 73 H00 . 2 7 )Ru2

J. W. Lynn, D. E. Moncton, L. Passell, W. Thomlinson

Phys. Review B (submitted).

Magnetic Properties of the Superconducting Alloy System

(Ce-j_

c Hoc )Ru

2

_ A Neutron Scattering Study

J. W. Lynn, C. J. Glinka

Journal of Magnetism and Magnetic Materials (submitted).

408
Neutron Scattering Studies of Crystal Field Excitation in

(RE)Mo6 Se 8

J. W. Lynn, N. Shelton

J. Appl . Phys. 50 1984 (1979).

Ammonium Azide

E. Prince, C. S. Choi

Acta Cryst. B35, 761-3 (1979).

Flat-Cone Diffractometer Utilizing a Linear Position-Sensitive

Detector

E. Prince, A. Wlodawer, A. Santoro

J. Appl. Cryst. 11 173-178 (1978).

Ground State Excitations in HoCo2 J. J. Rhyne, N. C. Koon

Inti. Journal of Magnetism (to be published).

Magnetic Excitations in Rare Earth Laves Phase Iron Compounds

J. J. Rhyne, N. C. Koon

The Rare Earths in Modern Science and Technology, Vol. 2 (to be

published).

Magnetic Properties of Laves Phase Rare Earth Hydrides

J. J. Rhyne, G. E. Fish, S. G. Sankar, W. E. Wallace

Journal De Physique C5-209 (1979).

Spin Excitation in Amorphous Transition-Metal Boron Glasses

J. J. Rhyne, J. W. Lynn, F. E. Luborsky, and J. L. Walter

J. Appl. Phys. 50, 1583 (1979).

Neutron Scattering Study of the Dynamics of (KCN)o .s(KBr)o .5 J. M. Rowe, J. J. Rush, D. G. Hinks, S. Susman

Phys. Rev. Letters (submitted).

Neutron Quasi elastic Scattering Study- of ND 4 + Orientational

Fluctuations in B-Phase ND 4 Br

J. J. Rush, J. M. Rowe

J. Chem Phys 69 2928-2930 (1978).

Absorption Correction for Weisenberg Diffractometers

A. Santoro, A. Wlodawer

Acta Cryst. (submitted).

Lattice Relationships: The Determination of Matrices That will

Relate Any Given Pair of Lattices

A. Santoro, A. Mighell, J. Rodgers

Acta Crystal lographica (submitted).

Neutron Powder Diffraction Study of Ta2Wo 8

A. Santoro, R. S. Roth, D. Minor

Acta Cryst. B (submitted).

409
Neutron Powder Diffraction Study of the Structure of CeTa04 , CeN6 0 4 , and NdTa04 A. Santoro, M. Maregic, R. S. Roth, D. Minor

Journal of Solid State Chemistry (submitted).

Use of Derivative Lattices in the Indexing of Powder Patterns

A. Santoro

Acta Crystal! ographica (to be submitted).

Neutron Scattering Study of the Methyl Group, Reorientations and

the Low Temperature Phase Transition in (CH 3 ) 2 SF2

C. Sleenberger, J. J. Rush

J. Chem Phys. 70 50-56 (1979).

A Study of Methyl Reorientation in Solid Nitromethane by Neutron

Scatteri ng

S. F. Trevino, W. H. Rymes

J. Chem Phys. (submitted).

An Observation of One-Dimensional Reorientational Tunnel Splitting

of the Ground and First Excited State in a Low Barrier System:

Solid Nitromethane

S. F. Trevino

J. Chem Phys. (in press).

Refinement of the Structure of Solid Nitromethane

S'. F. Trevino, E. Prince, C. R. Hubbard

J. Chem Phys. (submitted).

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. Chionette, and

J. N. Weinstein

FEBS Letters (in press)

Studies of Ribonuclease-A by X-ray and Neutron Diffraction

A. Wlodawer

Acta Crystall ographica B (submitted).

Seminars for Staff and Guests

B. Mozer

Neutron Studies of Critical Phenomena in Liquids

September 1978

F. Mezei

Neutron Spin Echo Spectrometry

October 17, 1978

K. Mollenbach

Small Angle Scattering Techniques

December 5, 1978

410
S. F. Trevino

A Study of Methyl Reorientation in Solid Nitromethane

Thermal Heat Division

February 1979

R. Swendsen

Monte Carlo Studies of Dynamic Scaling

March 11, 1979

K. H. Michel

Theory of Rotation Translation Interaction in Orientational

Disordered Crystals

March 26, 1979

C. White

Electron Self-Trapping Effects at Clean Si (111) Surfaces and More

Complex Interfacial Systems

March 28, 1979

Dr. Gelart

Electronic Band Structure of Metals and Alloys

April 1, 1979

N. F. Berk

Triplet Excitations in Molecular Crystals

April 4, 1979

V. K. Hardman

Magnetic Structures of Y6

(

l

r e 1 v Mnx ) 2 3

May 2, 1979 1_x

Dr. Hertz

Theory of Spin Glasses

May 15, 1979

F. Moussa

Elastic and Inelastic Neutron Scattering by Incommensurate Phases

of Diphenyl

July 1979

D. Richter

Localization and Diffusion of Muons in Niobium and Aluminum

August 9, 1979

J. S. Higgins

Recent Small Angle Neutron Scattering Experiments on Polymer

Mixtures

August 14, 1979

J. S. Higgins

Polymer Dynamics by Spin-Echo Neutron Scattering

August 15, 1979

411
R. M. Pick

Single Molecule Reorientatations in Plastic Crystals

August 20, 1979

Special Reports

Amorphous Magnetic Rare Earth Alloys

J. J. Rhyne

Chapter 16 of Handbook on the Physics and Chemistry of Rare

Earths , edited by K. A. Gschneidner and LeRoy Eyring, published by

North-Holi and Publishing Company, Amsterdam, The Netherlands in

1979.

Quasielastic Neutron Scattering and High Resolution Spectroscopy

J. J. Rush

NSF Workshop Report on "Present Needs and Trends in Neutron Crystallography and Spectroscopy."

November, 1978

Technical and Professional Committee Participation and Leadership

American National Standards Committee, N-17

R. S. Carter

Secretary

American Physical Society

R. S. Carter

Session Chairman

American Society for Nondestructive Testing

D. A. Garrett

Voting member of the Penetrating Radiation Committee, the Research

Committee, and the Personnel Qualifications Committee

American Society for Testing and Materials - E-7.05, "Nondestructive

Testing - Neutron Radiography"

D. A. Garrett

Secretary

Professional Engineering License - Quality Engineering - State of

Cal ifornia

D. A. Garrett

Program Committee for the National Center for Small Angle Scattering

Research

B. Mozer

Apparatus and Standards of the American Crystallographic Association

E. Prince

ANS - 15 Standards for Research Reactors

T. M. Raby

412
National Bureau of Standards Research Advisory Committee

J. J. Rush

Chai rman

Member Program Review Committee

National Center for Small Angle Scattering Research

J. J. Rhyne

Twenty-Fourth Annual Conference on Magnetism and Magnetic Materials,

J. J. Rhyne

General Chairman

Conference on Magnetism and Magnetic Materials

Advisory Committee*

J. J. Rhyne

Chairman

Rare Earth Research Conferences, Inc.

J. J. Rhyne

Member, Organizing Board of Director

The Rare Earths on Modern Science and Technology

J. J. Rhyne

Co-editor, published by Plenum Publishing

Technical and Professional Committee Participation and Leadership

American National Standards Committee, N-17

R. S. Carter

Secretary

American Physical Society

R. S. Carter

Session Chairman

Consulting and Advisory Data Centers

Graduate Center for Materials Research

V. K. Hardman

Adjunct Professor, Physics Department

J. J. Rhyne

Consultant, Argonne National Laboratory

J. M. Rowe

Member, National Research Council of Canada

Visiting Committee to the McMaster Nuclear Facility

J. J. Rush

413
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NBS-114A (rev. 9-78)

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