Institute for Materials Science and Engineering

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105-3188 V1986 C.2 NBS-PUB- ivcicti

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PUBLICATIONS

NATL

All 102487559

CERAMICS

NBSIR 85-3188

U.S. Department of Commerce

National Bureau of Standards

« — Technical Activities

100

.056

85-3188

1986

Institute for Materials Science and Engineering

CERAMICS

S. M. Hsu, Chief

C. R. Hubbard, Deputy

NBS RESEARCH INF0RYA7.

CEJ.TER

February 1 986

NBSIR 85-3188

U.S. Department of Commerce

National Bureau of Standards
DIVISION ORGANIZATION

STEPHEN M. HSU

CHIEF

(301) 921-2847

Bruce Steiner

(301) 921-2845 Camden Hubbard

(301 ) 921-2845

Mario Cellarosi

(301 ) 921 -2415

PROPERTIES/PERFORMANCE

Mechanical Properties

Glass and Composites

Tribology

Optical Properties

STRUCTURE/STABILITY

High Temperature Chemistry

Structural Chemistry

Ceramic Powder Characterization

Surface Chemistry and Bioprocesses

PROCESSING

Structural Science

Ceramic Chemistry

Sheldon Wiederhorn

(301 ) 921-2901

Stephen Freiman

(301) 921-2817

Ronald Munro

(301 ) 921 -21 1 3

Albert Feldman

(301 ) 921 -2817

John Hastie

(301) 921-3618

Stanley Block

(301 ) 921 -2837

Alan Dragoo

(301 ) 921 -2910

Frederick Brinckman

(301 ) 921-2969

Edwin Fuller

(301) 921-2842

Kay Hardman-Rhyne

(301 ) 921 -2838

ii
TABLE OF CONTENTS

INTRODUCTION

RESEARCH STAFF

TECHNICAL ACTIVITIES

PROPERTIES/PERFORMANCE

Mechanical Properities Sheldon Wiederhorn

Glass and Composites Stephen Freiman...

Tribology Ronald Munro

Optical Properties Albert Feldman....

STRUCTURE/STABILITY

High Temperature Chemistry John Hastie

Structural Chemistry Stanley Block

Ceramic Powder Characterization Alan Dragoo

Surface Chemistry and Bioprocesses. .. .Frederick Brinckman

PROCESSING

Structural Science Edwin Fuller

Ceramic Chemistry Kay Hardman-Rhyne.

.

OUTPUTS AND INTERACTIONS

Selected Recent Publications

Selected Technical/Professional Committee Leadership

Industrial and Academic Interactions

Standard Reference Materials

APPENDIX

Organizational Chart

National Bureau of Standards

Organizational Chart

Institute for Materials Science & Engineering

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INTRODUCTION

The Ceramics Division has been restructured with two factors in mind:

o Interest in ceramics continues to grow within the scientific

community; in diverse, highly technical segments of American

industry; and in the Federal agencies. This growing interest

requires close internal coordination of the Division’s programs to assure that they continue to be responsive to rapidly evolving

national interests and needs.

o The probability that a Department of Commerce budget increase for

advanced ceramics would be funded in fiscal year 1986 has grown

throughout the year. Careful program growth will require a broader

leadership involved in the response to the increasing national

interest

.

In order to address these factors, ten groups have been established under the

leadership of highly respected scientists. The programs of these ten groups

encompass areas of primary importance in electronic and optical as well as structural materials.

The overall objective of the Division's activity is to provide scientific

understanding, detailed measurement methods, standard reference materials and

standard reference data to enable U.S. industry to achieve key properties of

inorganic materials through advanced processing.

Four groups provide services primarily in the property and performance area.

In addition to well established groups in Mecnanical Properties and in

Tribology, the Glass and Composites Group is focusing attention on the role

of interfaces in atmospheric effects of fracture, with particular emphasis on composite materials. A new group has been formed to provide for the

Division's well-established program in optical materials.

Four additional groups furnish services primarily in the structure and

stability area. In the High Temperature Chemistry group, the joint American

Ceramic Society/NBS phase diagram program is placing emphasis on non-ox iae

materials and on materials of electronic and optical importance. The

Structural Chemistry group is concentrating its high pressure expertise on stabilization of high pressure phases for advanced processing of tough

ceramics. A new group on Ceramic Powder Characterization is providing

strengthened interaction with the Joint Committee on Powder Diffraction Data

Center. The Surface Chemistry and Bioprocesses group is developing new capability for surface characterization applicable to advanced ceramic

powders

.

In the processing area, two new groups have been organized to study

fundamental sintering processes and to bring advanced concepts of

molecular-level chemistry to bear on ceramics. These groups are working

closely with their colleagues in American industry, the university community,

and other Federal agencies to assure that measurement services to support

development of new ceramics are available in a timely manner. Close

1
interaction with the National Research Council Board of Assessment in

Materials Science and Engineering is one important way in which this assurance can be provided.

In addition to publications, technical society leadership, and scientific

collaboration, identified at the end of this report, the Division

collaborates with professional colleagues in other traditional ways.

Division staff gave more than sixty invited talks to industrial laboratories,

independent research institutions, universities, and professional societies,

in the U.S. and abroad. The Division organized three major conferences, one

on Basic Properties of Optical Materials, one on Biologically Induced

Corrosion and one on Ceramic Tribology.

Stephen M. Hsu

Chief

Ceramics Division

September 5, 1985

Updated, January 20, 1986

2
RESEARCH STAFF

PROPERTIES/PERFORMANCE

Mechanical Properties

Chuang, Tze-Jer

Chuck, Leon

Fairbanks, C. J.

Hockey, Bernard

Krause, Ralph F.

Lawn, Brian R.

McDaniel, Clyde

Roach, David

Tighe, Nancy J.

Wiederhorn, Sheldon M.

Glass and Composites

Blackburn, Douglas H.

• Ceramics

• Diffusional crack growth

• Finite element analysis

• Creep theory

• High temperature mechanics

• Scanning electron- microscopy

• Acoustic monitoring of cracks

• Microstructure/strength relations

• Ceramics

• Deformation and wear

• Scanning and transmission electron

microscopy

• Chemical equilibria

• High pressure-high temperature testing

• Vapor pressure measurements

• Refractories

• Microstructure/strength relations

• Fracture mechanics

• Contact phenomena

• Surface forces in fracture

• Ceramics

• Creep

• X-ray diffraction

• Surface forces in fracture

• Fracture mechanics

• Ceramics

• Creep at high temperatures

• Mechanical properties, high temperature

• Scanning and transmission electron

microscopy

• Ceramics

• Erosion

• Fracture processes

• Mechanical properties at high temperature

and pressures

• Special glass formulations

• Glass processing

• Glass standards for microprobe analyses

3
Cellarosi, Mario J.

Freiraan, Stephen W.

Inglehart, Loretta L.

Swanson, Peter L.

White, Grady S.

Tribology

Gates, Richard

Hsu, Stephen M.

Jewett, Kenneth L.

Ku, Chia-Soon

Munro, Ronald G.

Pei, Patrick

• Glass SRM development

• Glass standards for manufacture and use

• Glass property measurements

• Ceramics and glasses

• Fracture mechanics

• Mechanical properties, environmental

effects

• Thermal wave analysis

• Nondestructive evaluation

• Ceramic materials

• Ceramic fracture

• Microstructure

• Geologic materials

• Ceramics and glass

• Nondestructive evaluation

• Subcritical crack growth

• Friction and wear of materials

• Wear mechanisms and analysis

• Engine condition monitoring

• Ferrography

• Tribology

• Oxidation mechanisms of organic mixtures

• Lubrication and wear mechanisms

• Molecular structural effects on friction

• High temperature ceramic wear

• Organometallic speciation

• Oxidation kinetics

• Analysis of organic mixtures

• SRM research

• Oxidation kinetics . • Friction and wear test development

• Modeling of reaction systems

• Theory and modeling

• Tribology

• Molecular dynamics of phase stability

• Temperature modeling of ceramic pairs

• Separation of complex organic mixtures

• Trace organic compound identification

• Differential scanning calorimetry

4
Optical Properties

Farabaugh, Edward N.

Feldman, Albert

Frederikse, Hans P. R.

Steiner, Bruce W.

• Thin film deposition and analysis

• X-ray diffraction analysis

• Scanning electron microscopy

• Surface analysis

• Optical materials

• Thin films • Solid state physics

• Photoelasticity arid thermo-optics

• Guided waves

• Electrical and mass transport in solids

• Electrical conductivity

• Depth profiling (Rutherford

backscatter ing)

• Calorimetric absorption

• X-ray topography

• Optical materials

STRUCTURE/STABILITY

High Temperature Chemistry

Bonnell, David W.

Cook, Lawrence P.

Hastie, John W.

Ondik, Helen M.

Plante, Ernest R.

• High temperature-pressure mass spectrometry

• Computer modeling

• Levitation calorimetry

• Phase equilibria of ceramics (modeling

and experiment)

• Phase diagrams for ceramists data center

• Electron microscopy

• Thermodynamics

• High temperature chemistry of ceramics

• Ceramic phase equilibria and solution

models

• High temperature-pressure mass spectrometry

• Chemistry of combustion

• Phase diagrams for ceramists data center

• Materials properties for coal conversion

• Data compilation systems

• High temperature chemistry of ceramics

• Knudsen effusion mass spectrometry

• Vaporization thermodynamics

5
Roth, Robert S.

Schenck, Peter K.

Structural Chemistry

Block, Stanley

Piermarini, Gasper J.

• Crystal chemistry of ceramic materials

• Phase equilibria

• Dielectric and ionic conducting ceramics

• Phase diagrams for ceramists data center

• Laser spectroscopy

• Temperature measurement

• Computer graphics

• Properties, structure and polymorphism of

materials at pressure

• Ultra high pressure properties

• Crystallography and pressure phase

relations of ceramics

• Generation/measurement of high pressures

• Pressure/ temperature effects on ceramic

materials

• Generation/measurement of high pressures

• Physical and structural properties of

materials at high pressures and

temperatures

• X-ray diffraction, phase relations,

optical measurements

Ceramic Powder Characterization

Dragoo, Alan L. •

•

Hubbard, Camden R. •

Minor, Dennis B. •

Robbins, Carl R. •

Characterization of ceramic precursor

powders

Chemical bonds in solids

Corrosion of structural ceramics

Ceramic powder synthesis

Crystallite size and residual stress

Quantitative x-ray diffraction methods

X-ray diffraction standard reference

materials

Reference powder patterns

(JCPDS Research Associateship)

Analytical SEM of ceramics and particulates

Ceramic composites

High temperature ceramic synthesis

Fine ceramic particulate properties and

char act er i zat i on Spray drying; powder preparation

Quantitative microscopy and x-ray

diffraction

NDE of ceramics

6
Surface Chemistry and Bioprocesses

Blair, William R.

Brinckman, Frederick E.

Olson, Gregory

Parks, Edwin J.

PROCESSING

Structural Science

Blendell, John

Coblenz, William S.

Fuller, Edwin R.

Ceramic Chemistry

Coyle, Thomas D.

Frase, Katharine G.

• Ultratrace metals speciation

• Biotransformations of metals

• Environmental durability of coatings

• Molecular surface characterization

• Organometallic chemistry

• Biological mediation of surface chemistry

• Ultratrace metal speciation

• Metals biotransformation

• Bioprocessing industrial materials

• Epifluorescence microscopy imaging

• Surface modification and bioadhesion

• Metalloorganic synthesis

• Macromolecular organometallic chemistry

• Metals imaging in coatings

• Ultratrace metal speciation

• Controlled-release and bioactive polymers

• Ceramic processing and sintering

• Sol-gel chemistry

• Diffusion controlled processes

• Activation analysis

• Ceramic processing

• Sintering (theory and experiment)

• Covalently bonded ceramics

• Sol-gel chemistry

• Atomistic models of fracture

• Fracture mechanics of ceramics

• Fracture, environment-assisted

• Mechanical properties at high temperature

• Nondestructive evaluation

• Inorganic and organometallic chemistry

• Chemistry of materials processing and

durability

• Low temperature synthesis of ceramic

powders

• Chemistry of ceramic precursor material:-!

• Electrical properties

• Ceramic powder synthesis and process. eg

• Neutron scattering

7
Rhyne, Kay A. • Ceramic processing

• Small angle neutron scattering

• Nondestructive analysis

• Colloid and sol-gel chemistry

Ritter, Joseph J. • Synthetic inorganic chemistry

• Ceramic powders from organometallic

precursors

• Ceramic powders from gas phase, and

solution precipitation reactions

8
TECHNICAL ACTIVITIES

PROPERTIES/PERFORMANCE

MECHANICAL PROPERTIES Sheldon Wiederhorn

Ceramic materials are used where special properties, such as extreme

hardness, chemical resistance to corrosive environments, mechanical

resistance to erosion and wear, and mechanical and chemical resistance to

temperature extremes, are required. In practical applications, ceramics

are used as optical fiber waveguides, substrates for electronic

packaging, linings for geothermal wells, components for high-temperature

gas turbines and heat exchangers, cutting tools for the shaping and

finishing operations used in the manufacture of various machines and

tools, and insulating linings for reactors and furnaces in the

coal-conversion and petrochemical industries. In defense applications,

they are used in radomes, missile nose cones, turbine components in

portable electric-generating facilities, electronic guidance systems and

bearing surfaces in gyroscopes. Because they are brittle, ceramics are usually over-designed mechanically to avoid fracture during use. Investigations of fracture and deformation properties are needed to overcome technical difficulties associated with this brittle behavior, so that ceramics might be used in a wider range of applications. From a purely scientific standpoint, brittle fracture systems provide fundamental

information on the cohesive properties of solids, surface physics and

chemistry, and material microstructure.

Our program on mechanical properties has as its broad objectives: (1) the

generation of new theories and data to elucidate fracture and deformation

mechanisms in brittle materials; (2) the development of new techniques for

studying the fracture of and identifying defects in these materials; (3)

the collection of engineering data for structural applications; (4) the

investigation of processes that result in strength degradation and wear;

and (5) the investigation of ceramic microstructure and its relationship

to mechanical behavior.

Representative Accomplishments

o A microstructural dependence of fracture resistance was demonstrated

in polycrystalline ceramics using the controlled flaw technique.

Below a critical flaw size, the strength was found to be independent

of flaw size for a number of ceramics. This behavior differs from

the classical Griffith behavior, suggesting that the resistance to

fracture increases as the cracks grow larger. Because of these

results, methods of material characterization for lifetime prediction

will have to be modified to account for rising resistance curves for

fracture of ceramic materials.

o A new theory to explain fracture toughness of ceramic materials was developed. The source of the toughness of ceramic materials is

believed to originate in interlocking grains and unbroken ligaments

that cross between the crack faces. These apply a closure force to

the crack that must be overcome for fracture to proceed. ThJ 3 theory

implies that the toughness of ceramic materials can be enhanced by

microstructural design to increase the degree of Interlocking of

fracture surfaces. Studies have shown that this mechanism of

toughening is applicable also at high temperature.

9
o The role of surface forces in subcritical crack growth was explored

for ceramic materials. The equation developed to characterize the

effect of surface forces on crack growth suggests that surface forces

can account for a number of physical observations including the

healing of ceramics when the external driving forces are removed, the

change in slope of crack growth curves when the eternal environments

are changed, and the presence of fatigue limits in ceramic materials.

These theoretical predictions are being investigated through

experimental studies on mica and on glass.

o A study of creep in bending demonstrated that the neutral axis for

strain moves from the geometric center of the bend specimen toward the

compressive surface as the strain increases. Data of this type are being collected to confirm predictions of theories of multi-axis

creep. These results suggest that creep measurements obtained by both

tensile and compressive techniques are needed to understand fully the

creep of ceramic materials in high temperature applications.

o An analysis of the creep rupture of vitreous bonded aluminum oxide

indicates that failure of ceramic materials at high temperatures can

be divided into stress and strain limited modes, the latter being

more important for long term structural applications. These results

support data obtained on other structural materials such as hot

pressed silicon nitride and hot pressed aluminum oxide. They imply

that fixed strain relationships of lifetime prediction such as the

Monkman-Grant relationship will be more relevant at elevated

temperatures than fracture mechanics derived relationships.

Contact Damage and Flaw Studies

B.R. Lawn, C.J. Fairbanks,

R.F. Cook 2

D.E. Roberts, B.J. Hockey, Y.-W. Mai 1 and

1 Guest Worker, University of Sydney

2 Guest Worker, University of New South Wales

Contact damage studies using indentation methods provide valuable insight

into the fundamental deformation and fracture properties of materials.

They are now used widely in the ceramics community (perhaps more than any

other technique) as a means for evaluating critical material fracture

properties. They are used for determining surface stresses in highstrength ceramics; as a basis for modelling wear, erosion, and machining

properties of brittle materials; in the design of ceramic components for

potential strength-degrading applications; and as model flaw systems in

order to study the underlying the physical and chemical processes that are responsible for the initiation of small cracks. As such, contact damage

techniques afford a powerful route to the systematic study of the

micromechanics of small flaws, which control the strength of ceramics.

During the past year the effect of contact damage on the strength and

static fatigue behavior of a number of ceramic materials was studied. For

documentation of the propagation of cracks from indentation sites, discs

containing one indentation each in their center were placed on a test

fixture that was mounted on an inverted optical microscope. Loads applied

to the specimens caused the cracks to grow, and the crack growth was

10
recorded on a video tape recorder so that the qualitative aspects of crack

growth could be documented. Crack growth did not occur in a continuous

fashion but in incremental steps. Fracture was often interrupted at one

point only to restart at a second, nearby point. These results suggest

that interlocking grains and ligaments of unbroken material in the wake of

the crack front served to apply a closure force to the crack surface which

must be overcome for the crack to propagate. Based on the above

observations, a model of crack growth has been developed that derives its

resistance to crack growth from the unbroken ligamepts in the wake of the

crack front. This model has been used to obtain a prediction of strength

and failure time as a function of microstructure. The predictions are currently being tested in stress rupture studies at room temperature. The

output of this project is expected to suggest changes in current methods

of design for ceramic materials.

Chemically Effects in Crack Growth and Healing

D.H. Roach, B.R. Lawn and D.E. Roberts

The objective of this portion of our work is to understand the mechanisms^

by which a chemical environment can enhance crack growth rates in glasses

and ceramics. Our present state of understanding of chemically enhanced

fracture is primitive in the sense what while we can measure crack growth

or strength degradation rates, our lack of knowledge of specific mechanisms prevents us from selecting materials that have a maximum resistance

to crack growth. This same lack of knowledge prevents us from applying

fracture mechanics theory to predict component lifetimes that extend much

beyond the time range of the experimental data. Our research program is a means of obtaining this knowledge.

During the past year a study was conducted to determine the effect of

surface forces on crack growth in glass and mica at room temperature.

Fracture mechanics techniques were used to study crack growth and crack

healing in a number of environments: air, water, and aqueous

electrolytes. Crack growth studies of healed fractures indicate a strength increase with time; however the strength never reaches that of

the original material. The healing process is believed to originate from

surface forces whose origins are probably of a chemical nature.

Mathematical analyses of the type of behavior expected from such forces

are consistent with experimental observations: the occurrence of crack

healing, the observation of threshold effects during fracture and the

dependence of crack growth on environment. Experimental studies and

theoretical modeling during the coming year are expected to improve our understanding of the effect of surface forces on the fracture of ceramic

materials.

Flaw Propagation and Microstructural Effects

B.R. Lawn, A.C. Gonzalez, C.J. Fairbanks, D.E. Roberts and R.F. Cook 1

1 Guest Worker, University of New South Wales

Because the crack propagation resistance of ceramics is relatively low,

critical flaw sizes are reduced to a level at which they can become

comparable to the size of microstructural features (typically 5-50 ym ,
This comparability of flaw and grain sizes can lead to additional driving

and resistance forces on small-scale cracks, e.g., due to thermal expansion

anisotropy. It can also lead to an increase in the intrinsic toughness, as

a result of crack deflection processes, as fracture proceeds. An

understanding of the mechanisms of crack-microstructure interactions, and

the implications of these phenomena in relation to design with ceramics,

are the objectives of our work in this area.

The controlled flaw technique is an ideal method of studying the

dependence of fracture resistance on flaw size. Indentation flaws are placed into polished surfaces of ceramic materials, and strength is

measured as a function of flaw size. In conducting a study of this type, we found the strength to be highly dependent on the microstructure of the

ceramic. For some ceramics the strength was independent of crack size

below a threshold size crack. For others, the strength followed a classical brittle behavior in which the strength is inversely proportional

to the square root of the crack size. These results can be explained by a crack size dependence of the toughness of the material. Resistance to

crack growth increases as the crack grows larger so that the crack

propagates in a stable fashion, until it reaches a critical size

determined by the microstructure and the crack geometry. Thus, whether

the crack is small or large, specimens fail at the same breaking stress.

The existence of a rising resistance curve for fracture suggests that

microstructure is important to the lifetime and strength of ceramic

materials, and as such can be modified to improve the fracture behavior.

Because of the importance of a rising fracture resistance to strength,

additional studies will be conducted during the coming year to fully

evaluate the role of microstructure on toughness.

HiglvTemperature Deformation and Fracture

S.M. Wiederhorn, E.R. Fuller, Jr., T.-J. Chuang, N.J. Tighe,

R.F. Krause, Jr., B.J. Hockey, C.L. McDaniel, L. Chuck, G.A. Danko,

Y. Lu 1

, and J. Sun 2

Shanghai Institute of Testing Technology, Shanghai, China

2 Shanghai Institute of Ceramics, Shanghai, China

The development of new ceramics provides hope for high efficiency,

enhanced performance of structural systems in high temperature, stressbearing environments. However, before ceramics can be used in industrial

applications, issues concerning reliability and service life remain to be

resolved. With this in mind, our program on high-temperature properties

of ceramics entails five objectives: (i) the development of new theories

that are capable of predicting time-dependent fracture and deformation

behavior at specified loads and temperature; (ii) the development of new experimental techniques that can produce reliable creep data; (iii) the

generation of a data base on commercially available ceramics and

refractories; (iv) the investigation of kinetic processes that result in

strength degradation and delayed failure; and (v) the examination of

microstructures that promote understanding of mechanisms of response to

creep and creep rupture.

12
High temperature fracture studies during the past year concentrated on

four materials: partially stabilized zirconium oxide, magnesium chromate

refractory, siliconized silicon carbide, and aluminum oxide. In all of

these studies the strength or creep behavior was characterized as a function of temperature, time, and load.

Studies on partially stabilized zirconium oxide, a candidate for diesel

engines, indicate little loss of strength at temperatures up to 1000 °C

for exposure times of approximately 500 hours. At 1000 °C, a slight

increase of strength is observed as a function of time at temperature,

followed by a strength decrease after extended periods of loading. Since

the material creeps readily at 1000 °C, studies indicate the occurrence of

stress induced flaw generation as a function of creep, which eventually

causes the specimen to fracture. At 1000 °C the monoclinic phase grows at

grain boundaries at the expense of the tetragonal phase, and also

contributes to the strength loss. After exposure, the strength was highest at room temperature for all test conditions. Toughness tests on this ceramic show a very high insensitivity to damage; flaws up to

approximately 80 pm do not affect room temperature strength at all.

Magnesium chromate refractories are used as liners of slagging coal

gasifiers. Efficient operation of these gasifiers is required to produce

gas at a reasonable cost for commercial utilization, which implies high

temperatures of operation > 1500 °C. Present gasifiers are limited to

approximately 1500 °C because of chemical instability of the refractory

and the sensitivity of the refractory to creep rupture. In this project

the creep rupture of magnesium chromate refractory is being quantified to

correlate mechanical properties with failure mechanisms. Last year, the

creep rupture of as-received material was characterized as a function of

temperature and stress. The creep curves exhibited work hardening

behavior and the strain could be fitted to a power law function of the

time, in which the exponents and coefficients of the fit were both stressand temperature-dependent. The strain rate data were found to fit the

empirically derived expression to better than 5 percent of the strain

rate. The equations developed will be used in other parts of the program

to establish engineering allowables for coal gasification liners.

Creep-rupture studies of siliconized silicon carbide were conducted

because of the potential use of this material in heat exchangers. At the

maximum temperature of use of this composite, silicon is a highly ductile

metal, whereas silicon carbide is a completely rigid solid so that creep

of the composite therefore depends on the rheology of the silicon and the

way in which the silicon carbide affects the rheology of the silicon. Flow

of the silicon between the grains of silicon carbide accommodates the

deformation, but when the silicon cannot flow rapidly enough, cavitation

occurs. Cavitation and the growth and linkage of cavities to form cracks

are the main microstructural processes that limit the lifetime and

strength of this composite. During the past year, the creep and

creep-rupture behavior of siliconized-silicon carbide were characterize;

in four-point bending as a function of temperature and stress. It was shown that cavitation nucleates early in the creep process from

preexisting grain boundary defects. With additional deformation, the

nucleation and growth of defects continues, eventually resulting in .ir-v

cracks that lead to failure. As a consequence of the cavitation, trv

neutral strain axis for bending shifts towards the compressive surface jf

13
the test specimen. A method has been developed for locating the position

of zero strain and will be used to collect data that can be compared with

theoretical treatments of multi-axis creep.

The nucleation and growth of cracks at elevated temperatures was studied

on a commercial grade of vitreous bonded aluminum oxide by flexural

loading. This material was selected because it contained glass at the

grain boundaries and could be used as a model for structural materials

that are glass bonded. The strength of this material at elevated

temperatures was insensitive to the damage accumulated by the creep

process, suggesting a rising resistance curve for crack growth as the

crack grows from a subcritical to a critical size. This interpretation is

supported by the observation of ligaments of unbroken material along the

surfaces of propagating cracks. As in the case of our studies at room temperature, these ligaments increase the toughness of the material by

applying a closure force to the crack surfaces. Since cracks nucleate

along clusters of grain boundaries, deformation is believed to be

heterogeneous in this material. Creep-rupture data are shown to fit a stress-modified Monkman-Grant plot which suggests that a finite amount of

deformation is required in this material for the occurrence of failure.

Consistent with this conclusion is the observation that a relatively fixed

amount of strain is required in order to nucleate cracks in this material.
GLASS AND COMPOSITES Stephen Freiman

The Glass and Composite Group performs research in a number of areas with a strong emphasis on the mechanical properties of glasses, polycrystalline

ceramics, and ceramic matrix composites. In particular, there are major

efforts in the study of environmentally enhanced crack growth in brittle

materials, effects of ceramic microstructure on crack growth, and development

of fracture testing procedures applicable to ceramic matrix composites. In

this regard, there are cooperative efforts with personnel in both the

Mechanical Properties Group and the Processing Group -within the Ceramics

Division. There is also a considerable effort being placed in the

development of non-destructive evaluation (NDE) procedures for ceramics and

ceramic composites with emphasis on thermal wave analysis. In addition,

there is ongoing work related to the development of glasses that can be used

for x-ray fluorescence standards. The Glass and Composite Group is also

involved in the determination of glass viscosity over a wide range in

temperatures. This latter work is important from the point of view of glass

viscosity standards. In addition viscosity is one of the key parameters

which determines the creep behavior of polycrystalline ceramics that have

glassy grain boundary phases.

Representative Accomplishments

o Work on understanding the mechanism of stress enhanced chemical

reactions at crack tips has been extended from oxides to materials such

as III-V and II-VI compounds, e.g., GaAs, ZnSe, having variations in

their ratio of covalent to ionic bonding. Preliminary indentation crack

length procedures have shown that the fracture energy of these compounds

decreases with increasing ionicity of the chemical bond.

o Thermal wave techniques for porosity have been successfully applied to

alumina.

o Two new glass SRM’s have been developed for calibration of x-ray

florescence spectrometers.

Reactions at Crack Tips

Stephen W. Freiman and Grady S. White

Calculations of fracture energies based on a relatively simplistic model

agree very well with the experimental measurements. All of the materials

investigated, except for silicon, showed environmentally enhanced crack

growth in water. There is evidence that chemical compounds such as acetonitrile, which does not cause crack growth in Si02 in preference to

water, are much more effective in a stress enhanced crack tip reaction in the case of more ionic materials such as MgF

2 and ZnS. No environment was found

to produce slow crack growth in Si.

15
Microstructure/Crack Interaction

Stephen W. Freiman, Theresa L. Baker and Peter L. Swanson

Indentation-fracture procedures have been used to determine effects of starting

powder and processing conditions on the fracture behavior of a 9M percent

alumina. It was found that both the critical fracture toughness and the

strength of the aluminas were sensitive to the starting powder but not to

variations in sintering conditions. Deviations of the strength from that

predicted by the indentation model for small flaws were ascribed to direct

effects of the microstructure, possibly due to stresses generated by the

thermal expansion anisotropy in the material. The stress corrosion

susceptibility of the alumina was shown to be highly sensitive to the

starting powder, but again relatively insensitive to sintering conditions.

Differences in the subcritical crack growth behavior have been hypothesized

to be due to differences in the grain boundary compositions which have been

shown to differ markedly in their Mg0/Si0

2 and Ca0/Si02 ratios for the two

starting powders investigated to date.

Glass SRM's

Douglas Blackburn and Dale A. Kauffman

In cooperation with the Center for Analytical Chemistry, two thin film

Standard Reference Materials, SRM 1832 and 1833 have been developed and

issued for the calibration of x-ray fluorescence spectrometers. Each SRM

consists of a silica-base glass film deposited by focused ion beam coating

onto a polycarbonate substrate. The film consists of an amorphous glass

layer 0.5 - 0.6 urn thick containing known concentrations of selected elements

in oxide form. SRM 1832 is certified for Al, Si, Ca, U, Mn, Co and Cu, and

SRM 1833 for Si, K, Ti , Fe, Zn and Pb. Further work is in progress for the

development and certification of SRM's containing Si, B, Li, Pb, Sn, Cd, Sb

and Cr in one glass composition and Si, Al, Ba, Na, Ni, Mo, AS and Cd in

another glass. An ion sputtered arsenic sulfide glass film shows

considerable promise as a sulfur standard, and is surpisingly stable and

durable.

Thermal Wave NDE

Grady S. White, Loretta A. Inglehart and Martin P. Jones

The major NDE thermal wave effort for this year involves the measurement of

porosity in alumina specimens. The photo acoustic system built last year has

been used to obtain preliminary signal magnitude and phase data on NBS

prepared alumina specimens, which are 58 percent, 60 percent, and 98 percent

of theoretical density. Clear differences in both magnitude and phase are observed among all three specimens. In addition to the thermal wave measurements, the alumina is also being characterized by a number of other

techniques, e.g., light scattering, small angle neutron scattering (SANS),

porosimetry, and ultrasound, to provide as thorough an understanding of their

properties as possible. Such an understanding is vital to the development of

a quantitative model relating thermal waves to the measurement of porosity.

16
In addition, a mirage thermal wave system is being built at NBS to provide

imaging capabilities. The mirage system is designed to be computer

controlled and will allow detection and mapping of closed vertical cracks,

inclusions, and other localized defects.

17
TRIBOLOGY Ronald Munro

The wear of solid materials is one of the more pervasive cost factors that

affects every industrial, government, and civilian element in our society.

Tribology is that part of science that addresses the problems of wear and

the related problems of friction and lubrication.

The emergence of tribology as a distinct interdisciplinary field of study

has resulted from the recognition that the physical, chemical, and material

aspects of interacting substances are all crucial concerns of friction,

wear, and lubrication. The effects of these various aspects are coupled

together; i.e., the physical, chemical, and material aspects must be

considered at the same time.

The Tribology Group has developed a strong chemistry component to study

tribological interactions, particularly as they are mediated by a lubricating medium. Special emphasis in this work has been placed on the very

important regime known as boundary lubrication.

The subject matter of tribology is also prominent in current efforts to

develop materials for high temperature applications such as low heat

rejection engines. Advanced ceramics are the most promising candidate

materials for such purposes. However, at the expected high temperatures

(600 °C in the near future; 1200 °C in the distant future), traditional

lubrication substances and methods are not feasible. Similarly, common performance measurement approaches used to determine friction an'd wear characteristics are not feasible at high temperature.

Representative Accomplishments

• A unique new facility has been designed to study the friction and wear properties of ceramic materials at high temperatures. The principal

apparatus is capable of simulating the wear of both piston and ring and

cam and tappet engine component combinations. The environment of the

sample region has a controlled temperature which may be as high as 1500 °C. The atmosphere is also controlled allowing for studies in

oxidizing and nonoxidizing environments and for studies of novel

lubrication methods such as the chemical vapor deposition technique.

• A novel simulation method has been developed for prediction of lubricant performance at high temperature. The method is based on thermogravimetric analysis, a technique that uses a highly sensitive mass balance to detect variations in the mass of a milligram size sample as

a function of time and temperature. Successive experiments using inert

and oxidative environments permit thermal and oxidative characteristics

to be measured. Difference curves and derivatives of the weight loss curves are related to the molecular weight change of the chemical

species during the oxidation process. Relative comparisons of the

integrated areas under the difference curves and the derivative curves reveal quantitative information on the amount of interfacial reaction

products as well as the oxidative influence on evaporation under thin

film liquid/solid interface reaction conditions. This simulates the

heat engine cylinder liner/ring interaction.

18
Lubrication

P. Pei, R. S. Gates, C. S. Ku, K. L. Jewett, and R. G. Munro

Lubricating materials in tribological contacts react chemically with the

substrate material to form a surface film that is largely responsible for

the success of boundary lubrication. The efforts of this Group have

contributed significantly to the advancement of lubrication fundamentals.

Important steps have been made in resolving the very long-standing question

of what in a lubricating base oil actually is responsible for the lubricant's effectiveness. The question was attacked in two phases. First, a highly sophisticated base oil separation methodology was developed to study

molecular structural effects. The base oil was separated into its saturate,

aromatic, and polar fractions; and subsequently the polar fractions were

further separated into suofractions and then into compound classes.

Second, the separated substances were subjected to a variety of tests to

measure: oxidation stability; lubricating film formation tendencies; and

friction and wear performance characteristics. Subsequently, spectroscopic

studies were made on the most successful materials.

From these studies, model compounds were identified that would be representative of the substances producing the superior friction and wear characteristics. Performance tests conducted on the model compounds i-butyrolactone

and myristoyl chloride confirmed the deductions based on the spectroscopic

analysis. The insights i'nto lubrication fundamentals provided by this

effort could well require several years before being fully appreciated

because of the multitude of subtle features uncovered by the study.

Ceramics Tribology

R. S. Gates, J. P. Yellets, D. E. Deckman, and R. G. Munro

High technology ceramic materials have a tremendous potential for applications as structural materials. This potential for ceramics derives from

their outstanding thermal characteristics, high corrosive resistance, and

dimensional stability. The principal challenges in the development of chese

materials are related to the strength, durability, and wear resistance of

the materials. An integral part of the design and advancement of tnese

ceramics applications, therefore, is the performance testing and characterization of the materials. Currently, however, there are no standardized test

methods for evaluating the tribological properties of ceramics.

The Tribology Group has initiated a program in the tribology of high

temperature ceramics. The program involves the development of standardized

methodologies for friction and wear measurements; the simulation of engine’

component wear at high temperature; and the lubrication means and metnods

for ceramic materials at high temperatures

.

19
In the past, several wear test procedures have been successfully developed

at NBS for lubricated steel system. One of these procedures has been

selected by ASTM for consideration as a standard method for determining

coefficient of friction. The method established for lubricated steel systems has considered carefully the importance of material properties; wear

test geometry; load, speed, and temperature parameters; and systematic

pre- and post-test procedures.

The material properties of ceramics, however, are significantly different

from those of steel, to such an extent that entirely -new detailed procedures

are required. Some intriguing and novel features in ceramics friction and wear tests are now being discovered. These features will require incorporation into any standardized methodology for ceramics friction and wear measurement procedures.

Temperature effects have been found to be especially important for ceramic

wear processes. Figure 1 shows the coefficient of friction (COF) for

polycrystalline alumina under three different conditions, dry or lubricated

with paraffin oil or with water. The COF with water lubrication is greater

than the COF with paraffin oil. Thus, the heat generation rate in the

former case should exceed that of the latter case. Water, however, is a much better coolant than paraffin oil. Consequently, the temperature under

water lubrication tends to be lower than under paraffin oil. The result of

having a lower temperature is illustrated by Figure 2 which shows a measure

of the wear of the alumina specimens. The coolest system has the lowest

wear, despite not having the lowest friction. The hottest system has the

highest wear.'

Additional considerations arise for the testing of ceramic materials at very

high temperatures. The low thermal conductivity and thermal diffusivity of

ceramics results in the generation of very high temperatures in tribological

contacts. Estimates of peak temperatures at surface asperities have been as high as 2000 °C. Cooling occurs as the hot parts move away from the contact

zone. Consequently, large temperature gradients normally are produced in

standard test apparatus. These gradients obscure the understanding of the

intrinsic friction and wear properties. Therefore, the Tribology Group has

designed a new wear test apparatus for ceramic materials with the principal

feature being the minimization of large temperature gradients around the

contact zone.

The new facility features control of the temperature to 1500 -C, control of

the local atmosphere, and a sophisticated data acquisition, storage, and

retrieval system. The facility is expected to be fully operational early in

FY86, dependent on the delivery of unique and specially designed components.

The use of ceramic materials at high temperature also poses a very significant challenge to lubrication techniques. One methodology which provides a means for accessing the suitability of materials for high temperature

lubricating applications is thermogravimetric analysis. In a high temperature environment, lubricants are susceptible to numerous reactions including

oxidation and thermal stability. In heat engine applications, high vapor

pressure and oxidative volatility case excess lubricant loss through oil

consumption. On the other hand, amount of deposit formation on metal

20
LOAD, kg

Figure 1 . Coefficient of Friction an a function of Load for

Polycrynta Iline Alumina fro* Four-Ball Constant Condition

Testa Conducted at 600 rpm, 10 min duration, 10 ml

lubricant.

21
WEAR

SCAR

DIAMETER,

mm

5

DRY

LOAD, kg

Figure 2 . Wear as a Function of Load for Polycrystalline Alumina

from Four—Ball Constant Condition Tests Conducted at

600 rpca, 10 min duration, 10 ml lubricant.

22
surfaces is also crucial in engines. Thermogravimetric analysis provides a means of assessing the volatility and oxidative stability cnaracter istics of

potential high temperature lubricants.

A thermogravimetric method has been developed to assess candidate lubricants. In this procedure, 0.7 to 0.8 mg of lubricant is placed on a steel

catalyst disk contained within a gold pan. The sample is then heated at a rate of 10 deg/min from 50 to 550 °C. As the sample is heated, the percent

of sample remaining within the pan is monitored. After the sample is heated

in an argon environment, the catalyst disk is replaced, a fresh lubricant

sample is added, and the sample is heated in an oxyge.n atmosphere. Figure

3(a) shows the thermal and oxidative weight loss curves for an alkylated

naphthalene. In the thermal test 100 percent of the sample remains until

roughly 210 °C when evaporation becomes significant. Eventually, complete

evaporation occurs and no further weight loss is observed. Under an oxygen

environment, primary oxidation occurs forming decomposition products with

greater volatilities than the original sample. These molecules evaporate at

a faster rate than in the thermal case. Simultaneously, some of the primary

oxidation products react to form high molecular weight species which are

less volatile and evaporate at higher temperatures. Therefore, the oxidative weight loss curve eventually crosses the thermal curve and remains

above it until all products are evaporated as shown in Figure 3(a).

This new thermogravimetric method provides much critical information on lubricant stability. Subtraction of the two weight loss curves yields the

difference curve, which is displayed in Figure 3(b). The areas under the

peaks provide a quantitative comparison of relative oxidative volatility and

high molecular weight deposit formation tendencies of different lubricants.

The ratio of the two areas of a particular lubricant provides information on

the potential problem area of volatility rate with respect to deposit formation rate. If area A^ is much larger than A

2

, then oxidative volatility

could be the critical shortcoming for the lubricant. If A

2 is much larger

than A-j , then deposit formation may be the problem. When several lubricants

are compared, the relative oxidative volatility characteristics can be

quantitatively compared.

The derivative of the weight loss curve results in a weight loss distribution curve for the lubricant in the respective atmosphere on a steel

catalyst disk. The weight loss distribution curve obtained for the argon

atmosphere is equivalent to the boiling point distribution curve obtained by

distillation. The molecular weight distribution determined from the boiling

points of various molecular species is consistent with the distribution

analysis obtainable from gel permeation chromatography (GPC). The area

under the derivative curve equals normalized mass (m/m0

), where in 0 is the

initial mass of the sample. Figure M displays the negative of the derivative weight loss curve. Region 1 shows low molecular weight species formed

during oxidation and region 2 shows high molecular weignt species formed by

oxidation. The area under the oxidation curve shows the total mass of the

oxidized products.

23
0 l ’ 1 2 2 ! 2 * 1 1 u

60 160 260 360 460 560

60 160 260 360 460 560

Temperature °C

Figures 3(a) and 3 (d)

.

Thermogravimetric Data Obtained from the Analysis of an Alky

Naphthalene Mixture: (a) Thermal weight loss curve ( ), and

oxidative weight loss curve ( ); and (b) computer

(thermal-oxidative) difference curve.

24
Figure 4. TGA Derivative Weight Loss Curve for an Alkylated Naphthalene in

Argon and Oxygen.

25
OPTICAL PROPERTIES Albert Feldman

The objective of the Optical Properties Group is to provide data,

measurement methods, standards and reference materials, concepts,

evaluated data, and other technical information on the fundamental aspects

of processing, structure, properties and performance of optical materials

for industry, government agencies, universities, and other scientific

organizations. The program supports generic technologies in crystalline,

glassy, and thin film inorganic optical materials in order to foster their

safe, efficient and economical use. Research in the group addresses the

science base underlying new advanced optical materials technologies

together with associated measurement methodology.

Two principal areas of optical materials research are being covered:

Thin optical films addresses structure/processing relationships and

how they affect properties and performance as related to optical

coatings and integrated optics.

Materials for optical signal processing addresses

structure/processing relationships of crystalline electro-optical

materials important as modulator and optical memory materials.

In addition to the principal areas of activity, the group maintains the

capability to measure refractive index, thermo-optic constants and

piezo-optic constants of optical materials.

Representative Accomplishments

• A Topical Conference on Basic Properties of Optical Materials was

held at NBS May 7- 9 , 1985 . It was sponsored by the National Bureau

of Standards (NBS), the American Physical Society (APS), the Air

Force Office of Scientific Research (AFOSR), the Office of Naval

Research (ONR), the Army Research Office (ARO), in cooperation with

the Optical Society of America (OSA) and the Society for Photooptical

Instrumentation Engineers (SPIE). The 17 invited and 53 contributed

papers covered basic properties of materials as they affect

performance in advanced optical applications.

• Thin films in the zirconia : silica system prepared by coevaporation

showed significant densif icat ion compared to pure films of zirconia.

A simple model was used to estimate the pore fraction of films as a function of composition.

• Quantitative the Electron Spectroscopy for Chemical Analysis (ESCA)

measurements showed that coevaporated zirconia:silica films prepared

without backfilling with oxygen were significantly oxygen deficient.

The results correlated qualitatively with the presence of optical

absorption in the films. Pure zirconia and pure silica films were stoichiometric.

26
• Monochromatic x-ray topography experiments were carried out at the

National Synchrotron Light Source. Growth dependent defect

structures were observed in high quality single crystals of lithium

niobate and bismuth silicon oxide. These are the first such

experiments carried out in this country.

Thin Optical Filins

A. Feldman, E. N. Farabaugh, H. P. R. Frederikse, B. Steiner,

R. Stempniak 1

1 Guest Worker, Instituto Technolgico de Aeronautics , Brazil

Optical films of zirconia have been receiving considerable attention

because of their use as the high-index layer in multilayer optical

coatings for the ultraviolet portion of the spectrum. Several problems

are associated with electron-beam deposited zirconia films, and these

include index inhomogeneity. The index instability is caused by the

adsorption and desorption of water in the porous columnar structure of the

zirconia films. Index inhomogeneity is due to the inhomogeneous structure

of the films. One approach for producing bulk-like zirconia films that is

receiving considerable attention at present is ion-assisted electron-beam

deposition. We have demonstrated similar results when mixed

zirconia:silica films are produced by coevaporation from independent

electron-beam sources.

In most of the results discussed below two sets of films were used. The

initial set, prepared in a prior year, relied on manual control of the

deposition rate. The second set of films, prepared this year, were deposited with the use of automatic deposition rate controllers.

Last year, based on channel spectra and stylus measurements of the

thickness (t), we reported that a small addition of silica to zirconia

produces a film possessing a higher refractive index (n) than a pure

zirconia film. These results have been confirmed both by additional

independent measurements of n and t on the same set of specimens by m-line

spectroscopy, and by channel spectra and stylus measurements on a larger

number of the new second set of specimens. We have now shown that this

anomolous index behavior is consistent with a decrease of porosity in the

mixed films with the increasing content of silica. This result is based

on thickness measurements which show that the sum of the individually

monitored thicknesses of the two components is always less than the

measured thickness of the film.

If we define a nominal densif ication as a ratio of the sum of monitored

thickness to the measured film thickness, we find a densif ication of all

mixed films when compared to pure films of zirconia and silica. A simple

model has been used to estimate the porosity of mixed zirconiarsilica

films as a function of composition. The porosity deduced for pure

zirconia films is estimated to be 25-40 percent depending on the manner of

deposition. This is consistent with porosities estimated from our measurements of the effect water adsorption on refractive index and with

values reported in the literature. In addition, the mixed films appe .r to

exhibit a greater index stability than the pure zirconia films.

27
The effect of composition on the stoichiometry of e-beam coevaporated

zirconia:silica films was obtained by quantitative ESCA measurements.

Measurements of the area under the 0-j s

, Zr,d, Si 2p ESCA peaks yielded the

atomic fractions of 0, Zr, and Si. The films about 100 nm thick of

varying composition were deposited without backfilling with oxygen. After

preparation, the films were transferred directly to the analytic chamber

without breaking vacuum, thus avoiding specimen contamination. The pure

zirconia and silica films appeared to be stoichiometric. However, all the

mixed films exhibited oxygen deficiencies with the film having a 50:50

ratio of zirconia to silica being the most oxygen deficient. We are planning to determine whether backfilling with oxygen will lead to more stoichiometric coevaporated films.

These results correlate with the visual appearance of the new set of

specimens discussed above. Those films showed a significant optical

density with compositions closest to a 50:50 ratio having the darkest

appearance. Upon bakeout in air at temperatures ranging from 400-600 °C,

the films became fully transparent, with the most optically dense films

requiring the highest temperature.

Rutherford backscattering (RBS) experiments were made on the first set

specimens discussed above to examine depth uniformity. Looking at the Zr

signal, we found good uniformity at low silica composition, however, the

nonuniformity increased significantly with increasing fraction of silica.

0M85, Topical Conference on Basic Properties of Optical Materials

A Topical Conference on Basic Properties of Optical Materials was held at

NBS May 7~9, 1985. It was sponsored by NBS, The American Physical

Society, The Air Force Office of Scientific Research, the Office of Naval

Research, and the Army Research Office in cooperation with the Optical

Society of America and SPIE-the International Society for Optical

Engineering. A total of 204 people registered for the conference.

The purpose of the conference was to bring together researchers from

industry, academia, and government to discuss the physical and structural

properties of optical materials as they affect performance. The principal

topical areas covered were Effects of Microstructure, Infrared Materials,

Organic Materials and Polymers, Waveguide Materials, Surface Plasmons,

Thin Films, Properties from Millimeter to X-ray Wavelenghts,

Semiconductors and Quantum Well Structures, Nonlinear Optical Materials,

Optical Bistability and Glasses. There were 17 invited papers and 53

contributed papers.

Materials for Optical Signal Processing

B. Steiner, D. Roberts , R. Stempniak , A. Tanguay3

12

3

Student, Towson State University

Guest Worker, Instituto Technolgico de Aeronautica,

Consultant, University of Southern California

Brazil

Activities in materials for optical signal processing are focussed on both

optically passive and active materials.

28
In the active materials area, initial monochromatic topographic

experiments have been carried out during the first period of dedicated

beam operation of the x-ray ring at the National Synchrotron Light Source.

Samples of lithium niobate grown under a variety of conditions and of

bismuth silicon oxide were observed to display highly growth-dependent

crystal structure. We are working closely with industrial and university

crystal growers to identify the specific sources of crystal variation.

Parallel chemical analysis experiments are being carried out with neutron

depth profiling techniques at the Bureau’s research reactor.

29

STRUCTURE/STABILITY

HIGH TEMPERATURE CHEMISTRY John Hastie

Our program in high temperature chemistry and phase equilibria emphasises

the structural, thermodynamic, and chemical-kinetic behavior of materials

in high-temperature/high-pressure (gaseous) process and service environments

.

Phase equilibria, crystal structure, and reaction mechanisms of ceramic and

glass systems are determined through modeling and experiment. The Phase

Diagrams for Ceramists Data Center compiles and evaluates ceramic phase

diagrams in cooperation with the American Ceramic Society.

This activity serves new technologies, such as those based on processing of

advanced ceramics, refractory ceramic durability, nuclear waste management,

electronic ceramics, and more efficient fossil fuel combustion. Industry

and other government agencies use the results (a) for performance predictions and test method development in new high technology applications, and

(b) to support materials processing at high temperatures.

The research addresses: development of new or improved experimental

methods, their application to determination of basic data and new concepts,

modeling of cerami c/ metal gas-liquid-solid equilibria, and critical

evaluation and compilation of ceramic phase equilibrium diagrams. Molecular-specific experimental methodologies and theoretical modeling tools are

also being developed and applied to the determination of basic

thermochemical and kinetic data and chemical reaction mechanisms. In

support of phase diagram determinations, and for the completion of thermodynamic cycles in gas-solid-liquid equilibria, the characterization of

condensed phase composition and structure is achieved by x-ray or neutron

diffraction, scanning and transmission electron microscopy, and electron

spectroscopy for chemical analysis (ESCA).

During the past year, six inter-related subtasks have been carried out:

(1) Phase Diagrams for Ceramists Data Center; (2) Phase Equilibria and

Structural Chemistry; (3) High Temperature Chemistry; (4) Characteri zat ion

of High Temperature Gaseous Environments in Processing and Service;

(5) Data Center on Materials and Components for Fossil Energy Applications;

and (6) High Temperature Thermophysical Properties. The following

discussion will highlight the first three areas.

Representative Accomplishments :

o The National Bureau of Standards (NBS)-Ameri can Ceramic Society

(ACerS) five year expansion program for a ceramic phase diagram data

center, was implemented. Novel procedures were developed and

implemented for computer storage and retrieval of bibliographic

files and for diagram digitization, computer editing, topograph i :a manipulation, and preparation of production-quality ceramic phase

diagrams.

o A new experimental technique was developed, lasei— induced vaporization mass spectrometry, for determination of time-resolved

molecular-level mechanisms of very high temperature (> *4300 °C , pressure (> 1 atm) vapor plume formation from refractory mater, r.r. The method is being applied to graphite and is yielding new mechanistic details on the vaporization kinetics needed for mi’. ; *

. applications

.

31
o A book on "Construction Materials for Coal Conversion—Performance

and Properties Data" was completed for publication. This activity

represents an evaluated compilation of data provided by the

Department of Energy materials research contractor's reports. The

book completes the series covering alloy and ceramic materials.

o Using high temperature synthesis, based on the measured phase

equilibria, together with x-ray crystallography, a new chemical

homologous series of ternary phases has been identified in the

system Ba0 -Ti0

2 ~Nb2 05 . These phases are likely to have high

dielectric constants suitable for ceramic capacitors at microwave

frequencies

.

o New predictive phase equilibria models were developed and applied to

high-order oxide systems. The model has been validated for systems

containing solids and liquids of Li

2 o, Na20, K 2 0, CaO, MgO, A1 2

C>3,

FeO, Fe^^, Fe^Oij and Si0 2

. Several industries involved with steel

production and coal conversion (magneto-hydrodynamic, fluidized bed

combustion) are planning to make use of the model for process

design

.

Phase Diagrams for Ceramists Data Center

J. W. Hastie, L. P. Cook, H. M. Ondik, R. S Roth, M. A. Clevinger,

T. Brittle, M. Lukens, P. K. Schenck, and H. Parker 1 J. Bergen 2

, S. Cauley2

, and C. Messina2

1 Guest Worker

2 Research Associate, American Ceramic Society

NBS has a well-established joint data activity with the ACerS and is

closely coupled with current needs, as identified by NBS and ACerS advisory

committees. Recent research activity in this area has been expanded in

response to the increased complexity and quantity of new phase diagrams,

together with an expanded dependence by industry and others on critically

evaluated diagrams and related thermodynamic data. Basic objectives are

to:

improve the literature currency of the published phase diagram

volumes from 7 to 2 years;

expand systems-coverage to include carbide, nitride, boride,

compound semi-conductor and other systems, resulting in a comprehensive data base for all ceramic/inorganic phase diagrams;

this expansion will more than triple the number of diagrams

evaluated to date (past 50 years) over the next 5 year period;

- computerize the collection, evaluation, and dissemination

procedures to the maximum extent possible; and

enhance the utility and reliability of the phase diagrams through

research developments in modeling, thermochemical optimization,

computer graphics, and data base management.

(a) Evaluation/Production . Considerable progress has been made in the

preparation of Phase Diagrams for Ceramists Volume VI (oxides and oxygencontaining systems) and Volume VII (halides and sulfides) for which about

6800 phase diagrams are being considered. All of the literature for

32
Volumes VI/VII is in the critical evaluation process and an anticipated

completion date for Volume VI is December 1986. The cutoff for inclusion

of literature in these volumes is January 1983 (Chemical Abstracts date).

Volume VII will be the first to contain thermochemically optimized phase

diagrams. These diagrams will represent computer- drawn "best-fits" to

available phase diagram and thermochemical data, for alkali halide systems,

and will include experimental data points for comparison along with a detailed thermochemical critique. The first series of thermochemically

optimized diagrams for inclusion in the new volumes has been prepared under

contract with Prof. A. Pelton of The Ecole Polytechnique, in Montreal,

Canada

.

(b) Date Base Development . Progress has continued both in software

development and in file building for the bibliographic and graphics data

files. The bibliographic file software, developed in collaboration with

the NBS Office of Standard Reference Date, has been expanded and revised.

The software provides not only for the preparation of fully transportable

data files (all ASCII characters) of totally variable length but also for

the generation of files to feed other data bases and any rapid-search data

base management system. Each diagram has associated with it about 50 data

elements which include not only the full bibliographic reference but also

keyword information describing the diagram chemistry and experimental

conditions. The software provides methods for easy updating, editing and

rearranging of the data elements. It also allows the inclusion of Data

Center "bookkeeping" items to keep account of file history and to provide

the links to the phase diagram graphical data files. During the past year

the keyboarding of bibliographic material for Volumes VI and VII has been

completed

.

The very efficient prototype graphics input and editing software developed

earlier (FY84) for binary diagrams has been improved, documented as a users manual, and put into routine use. Over two hundred binary diagrams have

been digitized and edited for inclusion in Volume VI. Similar software for

ternary systems has been completed and is being tested for routine use by

the Research Associates.

(c) Modeling /Optimization . Current activities focus on: (1) the development of new solution models for phase diagram optimization and prediction

(2) incorporation and testing of NBS-developed solution models, and others,

into existing computer codes for phase diagram optimization, (e.g.; K.

Spear, Penn State), (3) application of the THERMFACT computer code, with

its extended regular solution model, to phase diagram optimization for

relatively simple molten salt systems, and (4) development of a thermodynamic data base for complex oxide systems, for use with the SOLGASMIX

(Ericksson, Sweden) and other computer codes applicable to phase equilibria

predictive modeling (W. Horton, consultant).

During the past year, a successful model has been developed for prediction

of solution activities and vapor pressures in binary and higher order

systems containing compounds (solid and liquid) of Li 20, Na 2 0, K

20, CaO,

MgO, A1 2

C>3, Si0 2 , FeO, Fe 20^, and FeoOij. This model has a thermodynami : basis and does not rely on an assumed molecular structure of the liquid

phase, or on experimental information such as mixing thermochemistry . "us- ability of the model to predict (as distinct from optimize) solution

thermodynamic properties for real-world highly non-ideal complex oxi

33
mixtures is shown by the example of Figure 5. Here, the model activity

data have been converted to partial pressures for comparison with our experimental Knudsen effusion mass spectrometry results.

In principle, the model should also permit calculation of phase diagrams

and this aspect is under investigation. Good agreement between model and

experiment has been found for the LijO-A^C^ phase diagram. One should

stress, however, that the viability and reliability of this model requires

continued experimental testing as additional components are added to the

database. Thus this modeling effort is closely coupled with -experimental

determinations of solution activities and phase equilibria.

Phase Equilibria and Structural Chemistry

R. S. Roth, L. P. Cook, K. Davis (Student), R. J. Cava 1

, H. Parker^, L. Ettlinger3

1 Guest Worker, AT&T Bell Laboratories

2 Guest Worker

^Research Associate, JCPDS

Experimental research performed in support of the Data Center program, and

for Other Agency projects, includes both classical determination of phase

diagrams (i.e., direct phase identification) and indirect measurement based

on Gibbs energy relationships. In the latter case use is made of vapor

pressure measurement using unique NBS facilities. These thermochemical

measurements of phase equilibria are particularly useful for testing

solution models under development for phase diagram optimization and

prediction. The classical phase equilibria program currently emphasises

oxide systems important to energy storage and for advanced electronic

ceramics. This latter activity involves close collaboration with Industry

(Trans Tech, Bell Labs) and Academia (P. Davies, University of Pennsylvania),

in addition to personnel from other Groups within the Division (K. Frase, J. Ritter, J. Blendell).

(a) Stored Chemical Energy Systems . During the past year, work was performed in response to basic data needs of the Office of Naval Research

(ONR) and Garrett Corporation for development of stored chemical energy

propulsion systems. The system of interest is based on the exothermic

reaction of a Li/Al alloy with steam to yield Li 20-Al 20o phases and

hydrogen, to be burned for additional thermal energy. Phase equilibria

determinations have been made in the system L^O-A^Oo using structural,

thermal analysis, vaporization and thermodynamic modeling techniques.

(b) Ceramic Dielectric Barium Polytitanate Systems . Various titanate

ceramics are currently used for communications and defense applications at

microwave frequencies varying from less than one gigahertz to four

gigahertz and higher frequencies. The dielectric properties most sought

after are high dielectric constant, high Q or. low dielectric loss, and zero

or low temperature coefficients of dielectric constant and resonance

frequency. Of current interest are materials with much higher dielectric

constant where the high Q is not as important but the low temperature

coefficients must be maintained. Compounds with a Ba/Ti ratio of 1:4 and

2:9 are currently used and the 1:5 phase was developed as a possible

candidate. Other phases with a high Ba to octahedrally coordinated ion

34
Partial

Pressure

of

K

(atm)

i LMPhKA i UKc K

2000 1800 1600 1400 1200

Figure 5

Model and experimental partial pressure data for K and

0

2 over an MHD slag

35
ratio without the presence of free rutile would be expected to have such

properties. Unfortunately none can be prepared in the binary system

BaO-TiOg

.

Recent research has concentrated on various barium-polytitanate phases and

their reactions with other oxides. Additions of low melting temperature

third components include V

2 o5 , M0O3, B2O3, P 2 05 and BaLiF 3

. Ba 2Ti90 2 p, the

major component in microwave filter devices, was found to be in equilibrium

with Ba^V2 0g and Ba 2V 2 0y in the ternary system Ba0-Ti02-V 2 05 . However, in

the ternary Ba0-Ti0 2-P 2 05 , rutile is in equilibrium with both Ba3P 2 0g and

Ba 2

P 2 0y, so Ba 2Tig02 o is equilibrated only with Ba3P20g. In this system

the reported phase 4BaO • 3Ti0 2

*P 2 05 was found to be a mixture of tribarium

phosphate and two barium polytitanates . Instead of this compound there is

another previously unreported ternary phase at approximately

1 2Ba0*2Ti0 2 .5P 2 05

.

Because of the chemical similarity between NbgO^ and Ti0 2 and the valence

identity between Nb + 5, V

+ 5, and P

+ 5, we have examined in detail the ternary

system Ba0-Ti0

2~Nb 20c . This very complex system contains many previously

unreported ternary phases. Several of these phases may have dielectric

properties of great interest in the communications industry for microwave

defense applications.

(c) Neutron Diffraction of Alkali Insertion Phases . A continuing cooperative project between NBS and A.T. & T. Bell Telephone Laboratories has led

to the structural refinement of a large number of new phases containing

alkali ions inserted into transition metal oxides. The compound LiV 2

c>5 has

eluded structural refinement for a long time. This was apparently due to

the use of an incorrect unit cell for indexing the pattern. Utilizing the

Visser program for indexing unknown powder diffraction patterns,

Dr. R.J. Cava of Bell Labs was able to arrive at a new unit cell which is more consistent with the data. This unit cell was then used to refine the

neutron diffraction data using Rietveld total profile analyses. Another

group of phases having the pyrochlore structure were also refined by

Rietveld analysis. These include KNbWOg, K 2NbWOg and KNbW05*0.69D2 0.

High Temperature Chemistry

J. W. Hastie, E. R. Plante, D. W. Bonnell, P. K. Schenck, A. B. Sessoms,

M. Wilke

This activity develops and applies new or improved measurement techniques

for the molecular-level analysis of high temperature vaporization

processes. The processes occur over ceramic solids and melts, coal slags,

glasses, and salts and in process atmospheres containing reducing,

oxidizing, carbonated, halogenated, sulfated, hydrous, and other reactive

components. These environments are characterized by extremes of temperature

(typically 10 - 5000 K), gas pressure (10“^ - 102 atm), chemical reactivity,

and phase complexity. The conditions and data obtained are generic to high

temperature ceramic processing environments, and in applications where hot

corrosion and high temperature oxidation are materials-limi ting factors.

(a) Nuclear Waste Glass Processing . Industrial and DOE plans for nuclear

waste storage require the waste to be incorporated into a borosilicate

glass. Vapor pressure data are needed for these glass-waste forms in order

36
to optimize the process conditions (e.g., temperature, composition) and

minimize losses of radionuclides by vapor transport during the high

temperature processing of the wastes. The primary objective of the present

study is to define the vaporization thermodynamics of simulated nuclear

waste borosilicate glass, containing non-radioactive isotopes, as prepared

by DuPont-Savannah River. Also, measurements of partial pressures for each

vapor species allow activities and related partial molar thermodynamic

functions to be derived. Such basic data are pertinent to the development

of thermodynamic models of other nuclear waste properties such as leaching

and storage durability. Special emphasis is being given to vapor species

containing the following elements which in actual nuclear waste form are highly radioactive: Cs, Sr, Ru , and Re (added as a technetium simulant).

(b) Stored Chemical Energy Propulsion . Knudsen-ef fusion mass spectrometric

measurements of species partial pressures and solution activities have been

made in support of the interest in phase equilibria in the L^O-AljC^

system. The results have beem used for phase diagram construction using

both the classical and Gibbs energy approaches. Also, the activity data,

obtained as a function of temperature and composition, will be used in

developing thermodynamic models of the heterogeneous reactions involving

H

2 0 and H 2

. An interim phase diagram has been constructed from the mass spectrometric data obtained to date.

(c) Laser-Induced Vaporization Mass Spectrometry . Degradation of materials

by high powered lasers is important in, for example, the design of laser

fusion processes, laser welding, laser processing of ceramics, and in the

durability of refractories in defense and space applications. In addition,

the use of lasers as point heat-sources has the potential for

characteri zing materials phase transformations at very high temperatures

and under essentially containerless conditions. We have undertaken

fundamental studies of laser-induced molecular level vaporization with

initial emphasis on graphitic and boron nitride materials.

Figure 6 shows a schematic of the apparatus developed for these studies. A very high pumping speed is maintained in the sample chamber to simulate the

environment of near-earth orbit conditions. Use of a Nd/YAG laser, with

adjustable nanosecond pulse duration, and collection of mass spectral

signals as a function of time provides a dynamic picture of the vaporization process. The apparatus also allows for multiple shots in a single

location thereby simulating cratering and ablation processes. A technique

for varying the laser beam impact angle has been developed to isolate

laser/plume interaction processes. Temperature, molecular weight and other

information is convoluted in the time resolved mass spectral profile and a model is under development to deconvolute these parameters.

Experiments on graphite show that this technique is capable of attaining

temperatures in excess of 4200 K, that the vaporization process is approximately at equilibrium, and that measured distributions of C

n polymer

species (n= 1 — 9 , or higher) are the expected equilibrium values.

37
Schematic of laser-induced vaporization

mass spectrometric facility (NBS 420).

Figure 6

38
STRUCTURAL CHEMISTRY Stanley Block

Knowledge of effects of high pressure and temperature on the structure,

phase relations, and physical, mechanical and chemical properties of

materials is necessary for their efficient industrial utilization. Such

information is essential, for example, for improving our understanding of

the parameters that are critical to ceramic processing and transformation

toughening in order to produce more fracture-resistant ceramic products.

The stability and retention of high pressure phases as toughening agents to

improve the properties of materials, particularly ceramics, is a new area

that requires attention. To carry out these investigations effectively, we must improve our measurement and standards capabilities at high pressures.

Representative Accomplishment;

o The concept of obtaining transformation toughening by pressure was conceived and evaluated. The high pressure tetragonal II form of

zirconia was obtained metastably, and the hardness and toughness of

compacts containing this material were determined. The results

confirm the concept of pressure transformation toughening. As a consequence of this, a new class of materials is now available with

the potential of improving the mechanical properties of ceramics.

Pressure Transformation Toughening

S. Block, G. Piermarini, J. A. M. da Jornada 1

1 Guest Worker, Universidade Federal do Rio Grande do Sul (UFRGS) and CNPq

Two criteria are necessary for transformation toughening of a ceramic

material. The first, (1), is the presence of a metastable phase uniformly

dispersed in a matrix of a stable phase. The metastable phase must be

denser than the stable phase or must have at least one crystallographic

cell dimension less than any one of those of the stable phase. This

condition produces either a molar volume increase or at least one larger

cell dimension on transformation to the stable phase. The second, (2), is

that the transformation must be rapid, characteristic of a diffusionless or

a martensitic-type transition.

Criterion (1) above is typical for high temperature phases, and only a few

examples with this anomolous behavior can be cited. However, as a general ruiv,

denser phases are always produced in any pressure-induced phase transition.

Thus, the phenomenon of transformation toughening i3 more general than

previously thought and is not limited necessarily to zirconia and hafnia.

If further major advances are to be made in this area of transformat Ion

toughening, they are more likely to be achieved by consideration of the

pressure variable.

The initial problem was to retain the high pressure phase in a metastab Le form at room temperature upon release of pressure. Studies were under:; i

. • n varying particle size, pressure, temperature, time and the hydrostat i c i ty

39
of the sample. Preliminary results indicated that all of these variables

contribute to the retention of the high pressure phase, but that relatively

low temperatures at elevated pressure were sufficient to make compacts

containing both phases. Zircar ZYP, which is a commercially available

product, was chosen as a standard zirconia powder. Compacts were made for

microindentation studies to evaluate the hardness and toughness of the new materials. These studies are being carried out in collaboration with

B. Lawn and B. Hockey of the Mechanical Properties Group.

Preliminary results, shown in Table 1 , indicate that hardnesses for the

compacts containing only the low pressure phase were only 4.4 GPa or less.

Samples with some retained high pressure phase have hardnesses ranging from

9.8 to 16.9 GPa with the larger value comparing favorably with the best

conventional zirconia ceramics. Moreover, the observed hardnesses appear

to be a function of pressure, sintering temperature and time, with higher

hardnesses being achieved through longer sintering times. A critical

factor to note here is that required sintering temperatures (500 °C or less) for this high pressure process are far less than the 1100 °C

temperature needed in the conventional thermal processes. The toughness of

any of the samples prepared so far has not been measurable because none of

the samples containing the retrieved high pressure zirconia phase

(tetragonal II) has shown any significant cracks around the anvil

indentation. It is these cracks which can be interpreted quantitatively in

terms of toughness.

Table 1 actually has two possible variables: 1) toughening agent and 2)

pressure sintering. Work is continuing to sort out these variables by

completing the studies on pure zirconia and initiating similar studies on stabilized zirconia. In collaboration with L. Cook of the High Temperature

Group, a search for other possible toughening agents with a lower

transition pressure and with a higher usable temperature range than

zirconia is being undertaken.

Pressure Phase Relations of Ceramics

S. Block, and G. Piermarini

The transformation pressure and high pressure structure of Zr0

2 :l8 mol#

Ce0

2 were studied by optical microscopy, x-ray diffraction and Raman

spectroscopy with P. Miller of NSWC. Briefly, ceria doped zirconia

converts to the cubic form at approximately 10 GPa. Preliminary studies

were also made on yttria doped zirconia. The transition pressure and high

pressure structure, i.e., tetragonal II or cubic depend on the yttria

concentration. As expected, preliminary studies of hafnia indicate a similarity to zirconia.

40
Table 1

Micro-indentation hardness tests on retrieved high pressure

samples of pure zirconia powder compacts.

SAMPLE SINTERING SINTERING SAMPLE RETAINED

PRESSURE TEMPERATURE TIME HARDNESS PHASE(S)

3.5 GPa 20 °C 1/2 hr - LP

7.6 ft 20 " 1/2 " - LP

3.2 tf 150" 1/2 " - LP

5.0 ft 250 " 1/2 " 4.4 GPa LP

8.6 Vf 250 ”

1 1/2 " 9.8 " LP-HP

8.5 ft 500 "1 1/2 " 13.0 " LP-HP

8.5 tl 500 ” 4

» 16.9 " LP-HP

LP = low pressure monoclinic phase

HP = high pressure tetragonal II phase

LP-HP = mixture of the high; and low pressure phases.

41
Kinetics of Decomposition of High Energy Materials as a Function of

Pressure

G. Piermarini, S. Block, and P. Miller 1

1 Naval Surface Weapons Center, White Oak, MD

This project, which is funded by the Army Research Office, is designed to

provide new information concerning the parameters that affect the kinetics

of explosive detonation and thermal decomposition processes of high energy

ordnance materials. The study of the phase behavior, melting point, and

decomposition of HMX (a high energy ordnance currently in field use) as a function of pressure and temperature was initiated. The primary probes

used in these studies are optical polarizing microscopy, fast Fourier

Transform Infrared Absorption Spectroscopy and x-ray powder diffraction.

42
CERAMIC POWDER CHARACTERIZATION Alan Dragoo

The formation of most ceramic materials begins with the processing and

consolidation of powders. Characteristics of a starting powder, such as grain size (primary particle size), agglomerate size (secondary particle

size), residual stress, internal porosity, particle shape, and chemical and

phase composition influence the properties of densified ceramics attained at

the outcome of the forming and sintering processes. The application of

ceramic materials in advanced heat engines, as components for electronic

devices, for improved cutting tools and in dense thin-layer components place

critical demands on the preparation and characterization of starting powders.

The task of the Ceramic Powder Characterization Group is to improve the

measurement of powder and fine particle characteristics and to advance the

understanding of how those characteristics influence properties of densified

ceramics. The work of the group is directed largely to the development of new Standard Reference Materials (SRM) for powder characterization, including

x-ray powder diffraction, and to the improvement of measurement

methodologies. Work in progress includes assessment of measurement variables

in particle size measurement by x-ray sedigraphy and photon correlation

spectrometry, identification and interpretation of particle characteristics,

correlation of powder characteristics with properties of resultant

green-state ceramics, and development of SRMs to enhance the accuracy of

x-ray powder diffraction. Shape analyses are being conducted on alumina wear

particles, mineral particulates, and a variety of commercially derived

powders to investigate relationships between shape parameters and powder

generation processes.

The work of the group is carried out primarily in two facilities: the

Automated X-ray Diffraction Laboratory and the Fine Powder Laboratory. In

addition a scanning electron microscope is used routinely for direct

characterization of powders. During this fiscal year a new semi-automated

x-ray powder diffraction system was selected and purchased. This system is

scheduled for delivery in July 1985. The system has much higher resolution

and sensitivity than x-ray diffraction equipment currently in use at NBS.

When it is fully automated, the system will permit the rapid acquisition of

high-quality phase data, both at room temperature and at temperatures to 1600

°C in vacuum. The high-temperature capability will permit the measurement of

thermal expansion and the study of phase changes. In addition to phase

identification studies, the system will be used to obtain data on sample

texture, residual stresses and crystallite size.

Both formal and informal scientific collaborations extend the range and

variety of the research activities. Under a program established with the

Joint Committee for X-ray Powder Diffraction-International Centre for

Diffraction Data ( JCPDS-ICDD) , research associates, with technical guidance

43
by NBS, provide critical evaluation of published powder diffraction data,

develop a numerical data base and provide "standard” powder patterns on selected materials. Collaborative work in x-ray powder diffraction also is

carried out with groups at Alfred University and the University of Maryland.

Industrial, academic and governmental laboratories provide a variety of

ceramic precursor powders for the NBS research program. Beginning this year

work will be undertaken to provide samples, measurement procedures, data and

data analysis as part of an international round-robin in characterization of

starting powders for ceramic materials for use in advanced heat engines.

Representative Accomplishments

• The second set of samples of SRM640a, Si x-ray line standard, were verified with respect to purity and consistency of the lattice

parameter.

• Alumina powders were spray-dried to form agglomerated spherical

particles which were subsequently calcined to yield either soft or hard

agglomerates. The agglomerates will be incorporated into samples for

Nondestructive evaluation (NDE) studies of processing flaws.

• Iron-rich centers were identified in pits which developed in the

cristobalite (Si02

) layer which formed on silicon carbide under active

oxidation conditions. The iron was present as an impurity in the

silicon carbide ceramic and is believed to have segregated due to the

low oxygen activity at the SiC-Si02 boundary.

• Temperature and oxygen partial pressure conditions were established for

the nondestructive incorporation of silicon carbide whiskers into a yttria-stabilized zirconia/zircon matrix.

X-Ray Powder Diffraction McMurdie* C. Hubbard, C. Robbins, A. Dragoo, H. *, W. Wong-Ng*, M. Morris*,

E. Evans*, M. Mrose*, B. Paretzkin*

*JCPD-ICDD Research Associates

Improvements in the resolution and sensitivity of x-ray diffractometers and

in computer control and data processing for those instruments have expanded

the already wide application of x-ray diffraction in research and industry.

This expanded use of x-ray diffraction has increased the need for standards,

for accurate powder diffraction data, and for improved measurement

procedures. Automated search procedures for rapid phase identification have

underscored the need for a reliable data base of x-ray powder diffraction

data.

Quantitative x-ray powder diffraction (QXRD) is of major importance to many

industries, including electronic and structural ceramics. QXRD is often the

only method available for determination of the concentration of phases in

44
materials. Unfortunately, QXRD methods are traditionally time consuming and

inaccurate due to the absence of standard procedures. Those limitations have

hindered the ability of industry to characterize fully solid phase materials.

Development of SRMs and improvement of procedures for x-ray powder

diffraction are objectives of the Ceramic Powder Characterization Group.

Several XRD SRM studies are currently in progress, including: selection of a new Si powder for use as a line position standard; selection of three

materials for use as x-ray intensity standards; selection of materials for a XRD profile standard; establishment of a cristobalite standard for

Quantitative XRD; and refinement of a large d-spacing standard.

The Powder Diffraction File (PDF) is of major importance to the mining,

ceramics, metals, and other materials industries where XRD is used to

identify solid phases. NBS assures that measurement methods and essential

reference data are available through its own research and by collaborating

with the JCPDS-ICDD to improve the internationally used PDF.

The primary objective of the ICDD-NBS program is to produce very accurate

x-ray powder diffraction patterns. An automated dif fractometer is used for

digital data collection. The data are processed with an extensive software

system. Accuracy in 20 measurements are typically ±0.005° compared with

+0.02° for strip chart recording procedures used on nonautomated instruments.

Intensities of the reference patterns are accurately recorded.

While reference patterns from the collaborative ICDD-NBS program are of high

accuracy, the majority of patterns in the reference file are not. Work has

proceeded this year on identifying and evaluating older powder patterns for common phases. New powder patterns are being prepared for materials where

inaccuracies in line positions, missing diffraction lines and errors in data

file are found to exist. In addition to experimentally measured patterns, a program is proceeding to supplement the data file with additional numbers of

calculated patterns. To improve the dissemination of the extensive PDF and

to increase the rate of data retrieval, optical disc systems are being

investigated for storage of the data base.

Powder Characterization

A. Dragoo, C. Robbins, D. Minor

A determination of a particle characteristic, such as size, shape and

porosity, generally employs the measurement of a macroscopic property whicn

is often related in an indirect manner to the microscopic character istics of

many particles. The science of powder character ization involves fundamenta

;

physics of the measurement process, sample preparation procedures *rhich

present problems in inter facial and colloidal chemistry, and the

interpretation and comparison of observations which are confounded by

different statistical assumptions and distributions. Thus, it is not

sufficient to provide, for example, an SRM for calibration of various

particle size measuring apparatus without assuring that the procedure:; m : data interpretation of those different instruments yield results tnat jut.

45
compared. In the case of starting powders for ceramic processing, the major

significance for powder characteristics lies in their impact on properties of

green-state and sintered ceramics.

Currently experimental procedures and data analysis are being examined for

the x-ray sedigraph, photon correlation spectrometer and microscopy/ image

analysis. In the near future Brunauer-Emmett-Teller (BET) procedures and

mercury porosimetry also will be examined. Fine silicon nitride and alumina

powders, and where appropriate, standard latex or polystryrene spheres, are being used for size measurements.

Measurement methods for particle shape analysis are being applied to powders

from a variety of sources to develop meaningful numeric descriptors for

particle shape. Data presented in Figure 7 were obtained from alumina wear particles. The data are presented in a three-dimensional plot which shows

the distribution of a number of particles (vertical axis) with respect to

DMAX (the maximum diameter or chord) along the horizontal axis and a form

factor, Form PE, along the receding axis. Form PE equals 1 for a circular

projected area and is less than 1 for an ellipse or an irregular shape. The

plot shows, first, that most of the measured particles had a DMAX < 1 ym and

that the smallest particles had approximately circular projected areas. Secondly, the plot shows that the projected areas of the large particles

became increasingly irregular as the particle size increased.

Preparation of Green State Ceramics for Nondestructive Evaluation

C. Robbins, W. Coblenz 1

formerly of the Structural Science Group, now at Norton Co.

The objective of this task is to prepare "green” (unfired) ceramic compacts

with known flaws for exploratory studies by nondestructive methods as well as by established destructive methods. Characteristics of the starting powders

and processing conditions that are used prior to the sintering of ceramics

are sources of many limiting defects that lead to early failure of finished

components.

During this fiscal year work was initiated on a high-purity alumina powder.

The powder was characterized by a variety of measurement techniques, and a large quantity of powder was processed to produce green compacts. The

compacts are to be studied at NBS by a variety of NDE methods, including

ultrasonics, thermal wave and small angle neutron scattering (SANS) methods.

SANS and ultrasonic measurements have been completed on an initial group of

alumina samples prepared without binder and other organic additives.

Structural Ceramics

A. Dragoo, D. Minor

Silicon carbide and silicon nitride ceramics generally contain a variety of

second phases. Those phases may be introduced intentionally - for example,

as sintering aids, reinforcing fibers or a pore filling phase such as free

46
OB? . F RE QUEMC V FORM PE.

Figure 7. and shape analysis of alumina wear particles.

d

?nJri\

Uti(

3 n 0f number of particles with respec size (DMAX) and projected particle shape (Form PE): circle; <1, ellipse or irregular shane.

The plot shows

to particle

Form PE = 1

,

47
silicon - or inadvertently as impurities during processing. Milling of

precursor powders often introduces tungsten carbide and iron inclusions. The

presence of the second phase may affect the reactivity of ceramic material.

Studies of a SiC ceramic containing iron as an impurity showed the presence

of iron-rich regions in pits in an oxide layer (cristobalite) which was formed on a SiC substrate under active oxidation conditions (low oxygen

pressure). A scanning electron micrograph with superimposed trace of the

iron x-ray signal is shown in Figure 8. At higher oxygen pressures (air at

1400°C) oxidation of the SiC substrate is passivated by a dense oxide layer.

Under those conditions hematite nodules were observed to have formed on the

surface of the oxide layer.

Zirconia-Sllicon Carbide Composites

D. Minor

The incorporation of SiC whiskers into an oxide matrix requires both control

of the chemical reaction during processing so that the whiskers are not

destroyed and an approximate matching of the thermal expansions of the

whiskers and the matrix. Since the thermal expansion of SiC is closer to

that of zircon, ZrSiO^, than to that of zirconia, Zr0 2

, incorporation of SiC

whiskers into the zirconia matrix requires the generation of a zircon sheath

around the whiskers without completely degrading the whiskers. The thrust of

the present work has been to elucidate the temperature - oxygen partial

pressure, P(0

2

), relationship between the competing reactions

Zr02 + Si0 2 = ZrSiOi|

SiC + 3/2 0

2

= Si0 2+ CO.

Pressed compacts of various compositions were heated in a controlled

atmosphere furnace, the resulting material was analyzed by x-ray diffraction

and fracture surfaces were examined with a scanning electron microscope

(SEM). Figure 9 shows a micrograph of a fracture surface. Preliminary

evidence shows that the whisker distribution and not the pressing regimen has

the greatest direct effect on the coherency of the final fired product. Under

the appropriate P(0

2

), the SiC whiskers showed little or no degradation and

negligible bonding to the matrix.

48
Figure 8. Scanning electron micrograph of cristobalite (SiO

?

) layer

on a SiC substrate with a pit containing a high concentration

of iron. The superimposed line at the bottom of the figure

is the iron x-ray signal.

49
Figure 9. Scanning electron micrograph of a fracture surface from

a SiC whisker/zirconia matrix composite.

50
SURFACE CHEMISTRY AND BIOPROCESSES Frederick Brinckman

The objectives of this Group are to provide essential data, accurate

measurement methods, and a quantitative mechanistic understanding of

chemically- and biologically-mediated events that control the design,

processing, and the performance or durability of novel or improved

inorganic materials. Consonant with recent programmatic restructuring of

the Ceramics Division and the Institute for Materials Science and

Engineering major new Group task thrusts feature strong concerted links

with major NBS initiatives, including advanced ceramics and biotechnology.

Special emphasis has continued on generating basic understanding of the

impacts of latest materials developments on service environments and

concurrently quantitating those environmental factors that dictate

durability of both end-use inorganic materials and their processing

components. Thus, Group research has provided information on prospective

means for selective bioextraction, recycling, and preservation of

strategic and precious materials, especially metals, in inert ceramic

containments

.

Within this framework, a novel molecule-specific surface imaging

capability under continuing development and demonstration, has already

accelerated our in-service performance testing of innovative specialty

designed organometallic coatings. These novel materials represent

multi-billion dollar Federal investments in defense and postal services.

Our imaging capability also presages unique on-line process monitoring

for, and durable reactor developments crucial to, emerging national

concerns for strategic and precious metals bioextraction and

bioprocessing.

Representative Accomplishments :

o At the request of the U.S. Navy, the first world-wide interlaboratory

comparison of methods for the trace quantitation and chemical

speciation of a major organotin biocide, tri-n-butyltin cation, has

been concluded. The methods study supports implementation of

organotin-containing antifouling paint coatings providing 100?

antifouling performance at sea for five to seven years, with initial

fuel cost savings for the U.S. estimated to exceed several hundred

million dollars annually.

o The solution and solid state chemistry of a water-stable

metalloorganic complex of terbium(III) has been measured with respect

to its efficacy and durability in a broad spectrum of organic

coatings applied to postage stamp papers in automated processing.

The new taggant's compatability and performance exceeds that of other

phosphors. Optical data (excitation and emission wavelengths,

quantum efficiency) owing to careful molecular design show major new

cost savings. Homogeneous, stable solutions nave been synthesized in

bulk and delivered in a non-toxic, non-flammable medium on a scale

suitable for forthcoming multi-million stamp production. A process

patent application has been submitted.

51
o Major components of a molecular surface imaging and bulk materials

characterization facility have been demonstrated, including Fourier

transform infrared (FTIR) spectroscopy to characterize coal

benef iciation by microorganisms, microscopic imaging to elucidate

metal accumulation on living microorganism with fluorescent metal

dyes and epif luorescence microscopy, and solid state NMR used to

develop novel structure/property relationships and characterize

non-destructively the structure of both crystalline and amorphous

polymeric organometallic solids.

o A bioprocessing facility has been assembled consisting of a high

pressure-temperature bioreactor and percolation columns, to be

coupled to an epif luorescence microscope and FT-IR system for

non-destructive on stream bioprocess monitoring. The system supports

new studies on potential novel, cost-effective methods for strategic

metal bioleaching and recovery, coal benef iciation and iron ore

benef iciation, all designed to provide quantitative understanding,

data, and process optimization for biotechnological processing

systems.

Inorganic Materials Bioprocessing

G. J. Olson, W. P. Iverson, F. E. Brinckman, F. Baldi 1

, R. Blakemore

2

, H. Ehrlich^, R. Kelly 1*, J. Thayer^

1 Guest Worker, University of Siena

2 Guest Worker, University of New Hampshire

^Guest Worker, Rensselaer Polytechnic Institute

4 Guest Worker, Johns Hopkins University

^Guest Worker, University of Cincinnati

Strategic minerals are critical to our economy and national defense. Yet

we rely on other countries for a number of raw materials, for which we

lack cost-effective technology to mine available domestic low-grade

deposits or recover critical elements from process on waste streams.

Microorganisms that solubilize or precipitate inorganic materials offer

low cost alternatives to convential processing and benef iciation of ores and fossil fuels. This is especially evident in the metal producing and

processing industry now faced with leaner domestic ores, strict

environmental regulations and increasing energy costs. Accordingly,

bacterially-assisted hydrometallurgical leaching of low grade copper ores

in the western U.S., for example, accounts for >200,000 tons of copper

production annually (nearly 2055 of the U.S. total) and is a major reason

for the survival of the domestic copper industry in the current depressed

world market. However, this biotechnology is still applied in a primitive

fashion because we lack scientific understanding of fundamental

solubilization mechanisms and rate-limiting or -accelerating factors.

Moreover, progress in this area has been seriously hindered by measurement

obstacles, especially in characterizing surface chemistries of substrates

in intimate contact with adsorbed microorganisms.

During the past year we have begun studies to explore strategic metals

biorecovery and microbial benef iciation of coal by sulfur and metal

removal; and domestic iron ore upgrading by phosphorus (P), sulfur (S),

silicon (Si) removal. Our research applies novel ultratrace molecular

52
speciation methods to surfaces and solutions associated with microbial

reactions in order to understand fundamental mechanisms, reaction products

and intermediates and optimization of processing conditions (Figure 8). In

this area we have applied our Group's experience in biocorrosion of

finished metals to the study of microbial dissolution of metal ores and

minerals, and provided the conceptual framework for selection and design

of desirable bioreacter containment materials featuring resistant

ceramics.

We have conducted a critical literature review, compiling the status and

potential of microbial processing for precombustion removal of sulfur,

metals and other undesirable elements from coal, and for ‘biological

liquefaction or oxygen/nitrogen removal from coal. Concurrent laboratory

experiments evaluated some promising candidate organisms that degrade

model compounds with structural similarities to coal. For example, a strain of Streptomyces decarboxylates vanillic acid, and when incubated

with coal, appears to remove oxygen as C0 2

, as shown directly by diffuse

reflectance FT-IR of the active process coal substrate.

High grade steels require removal of phosphorus impurities, and this is

most effectively done at the raw materials (ore) stage. U.S. ores are high in P and S and Si impurities, and the cost of their removal is high.

Microorganisms are reportedly capable of solubilizing certain forms of

these elements and potentially offer low energy, low cost alternatives to

current technologies. However, nothing is known about solubilization of

these elements from ores by microorganisms. Our work has shown production

of volatile P metabolites by iron corroding, anaerobic bacteria. We are now studying iron ore from a Michigan mine for P, S, and Si removal by

aerobic and anaerobic bacteria.

A teflon lined high pressure/temperature bioreactor system with gas and

liquid sampling ports has been assembled for on stream bioprocess

monitoring by epifluorescence microscopy, FT-IR, and other molecular

speciation instrumentation. Of special interest is the investigation of

the resistance of ceramic materials to corrosive biogenic metabolites at

elevated process temperatures and pressures. While conventional container

materials such as stainless steels are highly susceptible to these agents,

relatively inert ceramic containment offers prospects for fully exploiting

the developing biotechnology.

Initial work on processing has concentrated on fluorescent metal dye

systems to visualize metal species on active bacterial cells and in

solution. Quantitative epifluorescence microscopy showed that tin

bioaccumulation on cells is measurable with the fluorescent ligand

3~hydroxyflavone. Experiments underway using porous glass beads with tin

coordinated to mercapto groups covalently bonded to the glass also show

that tin(IV) can be imaged nondestructively on a materials surface with

the flavone. These experiments also reveal metal bonding characteristics

on cells and materials.

Initial metal leaching experiments have examined the effects of cinnabar

(HgS) on microbial metal sulfide solubilization, since this mineral is

considered a potential toxicant when present in an ore supply.

Previously, we demonstrated that a mercury-resistant strain of the

commercial ore-solubilizing bacterium Thiobacillus ferrooxidans had the

53
FIGURE 8. Components and flow diagram of the new bioprocessing facility.

Raw materials are processed in a teflon-line bioreactor by

micro-organisms, or their exocellular metabolities , at ambient

conditions or under elevated temperatures and pressures.

On-stream analyses (dashed lines) of gases is performed by gas

chromatography (GC) coupled to an element-specific flame

photometric detector (FPD) or mass spectrometer (MS), and of

liquid samples by Fourier transform infrared spectrophotometer

(FTIR) or epif luorescence microscopic imaging (EMI), following

liquid chromatographic separation with post-column

derivatization by metal-specific fluorescent ligands to detect

and quantify key process products. Solids are also characterized off-line (solid lines) by surface imaging methods, including

scanning/transmission electron microscopy with energy-dispersive

x-ray microanalysis (STEM-EDX), and the mentioned FTIR and EMI

techniques. Process containment is critical under such highly

corrosive bioprocessing conditions and evaluations of the

durability of various conventional and advanced non-metallic

contact materials are being performed to insure appropriate

development of cost-effective scale-up bioprocessor

developments.

54
potential to process ores in the presence of mercury. In collaboration

with F. Baldi of the University of Siena, we are examining

mercury-resistant T. ferrooxidans from cinnabar deposits in Italy. The

organism has oxidized pyrite the presence of HgS, producing Hg°. A

Hg-sensitive strain was inhibited under the same conditions. Thus,

mercury-resistant bacterial species may be useful in bioprocessing of

cinnabar-containing ores.

Inorganic Materials In-service Performance and Durability Studies

E. J. Parks, W. R. Blair, F. E. Brinckman, T. L. Lockhart 1, C Matthias 2, J. M. Bellama2

, D. Ollivon^, C. Valeiras-Price2

, P. Dougherty 2

^RC-NBS Postdoctoral Research Associate, 1984-1985

p Guest Worker, University of Maryland

^Guest Worker, Universite Marie et Pierre Curie, Paris

Non-Destructive Nuclear Magnetic Research (NMR) Measurement Methodologies

for Ceramic Materials Analysis. The past year has seen important new developments in our basic research effort to develop new measurement

methodologies and technical data bases for the characterization and

prediction of materials properties using NMR spectroscopy. This project

has led to the discovery of highly accurate NMR/structure correlations

from solid-state NMR measurements of structurally-characterized

organotin(IV) substrates and represents the first time that this

fundamental capability of solid-state NMR has been recognized explicitly

and exploited. With this new data base, we are now able to carry out the

molecular characterization of organotin(IV) materials with a high degree

of refinement. Most importantly, our approach is general and has clear

implications for numerous other spin-active metals or metalloids which

play critical roles in inorganic and organometallic materials, including

ceramics, glasses, and catalysts. The accuracy of the new relationships

(of C-Sn-C angle to the magnitude of tin-carbon J coupling, [

1 J ] ) has been

demonstrated. Several predictions of the molecular structure were shown

to be correct by subsequent x-ray structure determination carried out by

several groups of university collaborators. We have established the

ability of the technique to distinguish between different, closely-related

crystalline modifications of a single compound and to indicate the

presence of more than one molecular structure within a single

modification. Preliminary results suggest that this may become the most

sensitive and convenient method for revealing polymorphism for a range of

inorganic materials. With this NMR technique we have identified an error

in a published single-crystal x-ray structure.

Obvious applications of interest to ceramics science are the capabilities

of the new methodology and technical data base for use in the

determination of molecular structures of both amorphous and polymeric

precursor inorganic materials. We have carried out detailed structural

analyses on a number of organometallic polymers.

Innovative Coating Technologies-Materials Design, Synthesis and

Performance Testing. Two major categories of large-volume commercial

specialty coatings are now emerging, particularly as stimulated by

innovative coating requirements. In one category are phosphorescent taggants commensurate with existing automated

55
facer-cancelling equipment, applied to 40 billion pieces of mail per year.

In the second category are slow-release biocidal antifouling coatings used

to protect ships, buoys, and wooden pilings from marine microorganisms.

State-of-the-art tagged coatings have given serious problems because they

consist of an organic varnish charged with a high percentage (10-20

percent) of immiscible inorganic phosphor (typically zinc orthosilicate

doped with manganese) . Such coatings are readily abraded at the expense

of phosphor brightness. Corrective measures are necessary that cost well over twelve million dollars annually, since false negative stamps must be

examined and cancelled manually, causing substantial added labor costs and

delays. Available metalloorganic phosphors have a drawback in low quantum

efficiency (brightness). We have developed a metallorganic terbium

complex in which eight molecules of a bidentate heterocylic aromatic

compound [2,6-pyridine dicarboxylic acid (DPA), or its sodium salt], are bonded to the central terbium in a single aquated macromolecule. Although

a pure tris-DPA solid metallorganic complex synthesized from the same components had been known for years, our study of the complex in aquatic

solution proved distinctly different properties (Figure 9) detected only

by microbore chromatography coupled with epifluorescence microscopic

imaging (EMI). We have demonstrated that eight ligand groups, surrounding

the Tb ion in solution, contribute additively to the maximum

phosphorescence. In the crystalline phosphor, only three DPA molecules

are accommodated by the central Tb(III) atom. The high quantum efficiency

resulting from extended ligand interactions is retained on mixing the

aqueous solution into the organic varnishes in current production. The

next result is an end-process phosphorescent coating in which trace

quantities of terbium (0.03 to 0.11 percent) as the miscible

metalloorganic complex perform more effectively than 10-20 percent of

current inorganic phosphor in domestic use.

This novel phosphor, moreover, holds the promise of direct application of

an aqueous solution rather than a varnish to certain papers, which would

greatly enhance the clarity and the esthetic value of numismatic stamps.

We expect to apply FTIR to the detailed characterization of two predicted

bonding situations affecting a single molecule: outer sphere coordination

of terbium with the carboxylic acid substituents of DPA, and inner sphere

coordination between nitrogen and terbium.

Coatings in the second category, organotin containing antifouling

materials, will experience increasing usage during the next few years,

affording five to seven years of antifouling protection for each

application and saving hundreds of millions of dollars annually in fleet

fuel costs. We have developed molecular speciation methodology to allow

assessment of the environmental impact of the new organotin antifouling

formulations. Of critical importance to any monitoring program for new materials with environmental applications are standard methods and

reliable reference materials for assurance of data quality, reliability,

and intercomparability of data. We have completed an international

intercomparison of organotin measurement methods. Thirty-five

participating industrial, government, and academic laboratories reported

results of the analysis of our chromatographically-prepared aqueous

tributyltin research material (Figure 10).

56
Luminescence

75

<0c

3»t-<0 n

w

(0

5 10 15

Molar ratio

DPA : Tb

FIGURE 9. A new measurement concept is providing breakthroughs for design

of novel phosphor coated materials. The Group-developed u

- bore

HPLC coupled with an on line epifluorescence microscope imager

(EMI) as detector has permitted us to demonstrate the optimal

stoichiometry versus luminescence in aqueous terbiura(III) DPA

complexes, a previously unknown phenomenon. Further applications of y-HPLC-EMI have allowed effective synthesis and

incorporation of the new phosphors in majoi—scale postage st<imp

testing, where its demonstrated durability and quantum efficiency presages significant cost savings of $12-25M per year.

57
1

1

DEVIATION, ppm Sn

Figure 10. The frequency distribution of reporting laboratories in six

countries (total = 35, 3 outliers not shown) correlates errors

in total tin analysis methods (A through G) at their option. The true value of Sn in the tri-n-butylt in moiety determined at

NBS by three independent methods (NAA, GFAA , GC-FPD) was 1 ppm

nominally in the aqueous reference solution supplied. No

single method was statistically favorable in the present study, but more than half (57$) of the participating laboratories

reported results within RSD = ± 10$.

58
The new organotin coatings technology carries with it potential adverse

environmental impacts from the leached biocide. We have developed

monitoring methodology to investigate the environmental fate and effect of

butyltin compounds, including biodegradation, bioaccumulation and

partitioning. Hitherto, investigations in these areas were limited by the

lack of reliable butyltin chemical speciation measurement methods in

seawater at parts-per-trillion (environmental) levels.

Our new measurement methods also support studies characterizing rates and

mechanisms of tributyltin degradation in estuarine environments. We find

that biodegradation of tributyltin at ppb levels in Chesapeake Bay samples

is slow unless nutrients are added to encourage microbial activity. This

results in apparent debutylation to less toxic di- and monobutyltin

species. However, analyses of surface microlayers and biofilms on or near tributyltin painted ship hulls revealed the presence of tetrabutyltin,

which we reported for the first time in the environment, and other

tin-containing metabolites. This suggests a more complex chemical pathway

in the environment than heretofore believed, including redistribution

reactions. This has important implications for the impacts of tributyltin

use, since biofilms are present between the antifoulant paint and the

surrounding seawater. Our nondestructive surface analysis facility,

including FTIR and epifluorescence microscopy components, are now being

applied to examine these surface reaction mechanisms.

59

PROCESSING

STRUCTURAL SCIENCE Edwin Fuller

The Structural Science Group is a newly formed group whose focus is the study

of the structure of ceramic materials and the relation of this structure to

the processes that formed it (ceramic processing) and to the properties and

performance that it determines. Characteristic structural features of

ceramic materials range from the molecular, or nanostructure scale to the

microstructural level. Important features at the molecular level include

crystalline defects (vacancies, interstitials, dislocations, etc.);

interfaces and grain boundaries; and impurity chemical concentrations. At

the microstructural level important features include grain size and

morphology; second-phase inclusions and pores; and distributions of these

entitles.

Ceramic structure lies at the heart of surmounting the two major impediments

to the production and use of advanced ceramic materials. The first of these

impediments is the ability to capitalize effectively on the unique properties

that advanced ceramics have ("use what we have"). The uninitiated designer

is not familiar with these properties, and the key materials data and

understanding required to educate him are lacking. The second impediment is

that understanding of advanced ceramic materials is not "mature" enough to

tailor properties to a specific application ("develop what we need"). The

experienced ceramics designer would like to specify the property combination

needed for a specific applications, but frequently cannot due to a lack of

understanding of how the properties can be achieved by ceramic processing.

Knowledge of structure addresses both of these areas. Structure controls the

properties of the ceramic materials and is determined by the ceramic

processing. Understanding of these connections can lead to effective ceramic

design.

The research effort has two main areas: Fundamentals of Interfaces, and

Structure/Property Relations. In the first area, interfacial properties,

such as interatomic forces, surface and grain boundary energies, defect

concentrations and formation energies, and impurity species are studied and

related both to ceramic sintering and to brittle fracture. In the second

area, the relations between microstructural features and fracture behavior

are studied (toughening mechanisms at low temperature and creep rupture

mechanisms at elevated temperature).

Representative Accomplishments

o The observation that otherwise stable interfaces (grain boundaries and

thin liquid films between grains) can be induced to migrate by the

diffusion of a solute into the solid has led to new understanding of the

driving force for interfacial migration.

o Growth of quartz seed crystals in a sol gel environment has been

observed. This is an initiated step in the low temperature production

of tough transparent ceramics for high performance applications.

61
Diffusion Induced Boundary Migration In Ceramics

J. E. Blendell and C. A. Handwerker 1

Metallurgy Division, IMSE

Interface migration due to diffusion (DIGM) that occurs at low temperatures

leads to alloying at much faster rates than predicted- for diffusion with

static interfaces. Liquid film migration has been observed for the first

time in a ceramic system. Fine MgO powders were mixed with V

20^ and heated

above the melting point of VpOc. The M80 gra i ns coarsened and spheridized.

Upon addition of NiO (or CoO) the liquid film between the MgO grains migrated

against its radius of curvature and formed a solid solution in the reigon

swept out. This is in agreement with a model based on the coherency stress

as the driving force for this previously unexpected boundary migration.

While this type of boundary migration has been observed in a wide range of

metallic systems, the conditions for migration in ceramics were not known.

Experiments to observe boundary migration in the absence of a liquid film are currently under way.

Closure and Repropagation of Healed Cracks in Silicate Glass

E. R. Fuller, T. A. Michalske 1 and E. R. Fuller

Mandia National Laboratories

Crack closure and subsequent repropagation of healed cracks were studied in

soda-lime-silica and vitreous silica glass. Cracks were observed, by

birefringence pattern of the crack-tip strain field, to close against a finite load at humidities between 0.01 and 100 percent. The force associated

with crack closure (0.15 J/m2

) was predicted by a model that involves

hydrogen-bonded linkages of surface adsorbed water molecules. The fracture

energy to reopen healed cracks in vitreous silica has been determined to be

in the range of hydrogen bonding interactions. At the driest environments

used, healed cracks in soda-lime-silica glass required 1.7 ^0.2 J/m2 to

reopen. This bonding energy can be attributed to either the formation of

cationic bridges or siloxane bonds between fracture surfaces. Since crack

healing is independent of the number of cycles, the cationic bridging model,

which involves electrostatic interactions, is favored to explain healing

effects at room temperature.

Crystallization of Sol-Gel Glasses

J. E. Blendell and J. B. Blum1

1 Rutgers University

Many ceramics have been produced by sol-gel techniques at lower temperatures

than is possible with conventional powder processing. However, the

crystallization process is difficult to control to achieve the proper

62
crystalline phase assemblage. Controlled nucleation was used in an effort to

make crystalline quartz via sol-gel techniques, to produce a tough

transparent ceramic that may replace for glass in high performance

applications. Heretofore, high-density polycrystalline quartz has only been

produced under hydrothermal conditions. When powders are sintered in air at

high temperature cristobalite forms, while at low temperature no densif ication occurs. Dense SiC^ glasses can be made by sol-gel processing,

and if the desired phase can be nucleated it would be possible to produce

polycrystalline quartz. Nuclei were introduced during sol-gel processing of

silica glass in collaboration with Prof. John Blum of- Rutgers University.

These sol-gel glasses with differing amounts of quartz seed (2-10 percent by

weight) were heat treated over a range of temperatures. At 1000 °C

crystobilite begins to form in less than a day. At lower temperatures

(850-950 °C) the quartz phase begins to grow, but the kinetics are slow.

Annealing for times up to 3 weeks at 900 °C leads to a small increase in the

amount of quartz present as determined by x-ray diffraction. No other phases

are detected. Much longer annealing times are required to determine whether

fully crystalline quartz will be produced.

Ba/Ti Ratio Measurement

J. E. Blendell and R. F. Fleming 1

Center for Analytical Chemistry

Gamma-ray spectroscopy was used to measure the Ba/Ti ratio in compounds

having the BaTicO^ structure in collaboration with Ron Fleming of the Center

for Analytical Chemistry. The samples were found to be Ti rich, that is

[Ti]/[Ba] > 5. This implies that a substantial concentration of defects must

be present in order for the sample to have the BaTicO^ structure. Such

defects are thought to be responsible for the excellent microwave dielectric

properties of other high Ti compounds in the Ba-Ti system. It is possible

that these defects will lead to temperature independent dielectric properties

in the 1:5 material.

63
CERAMIC CHEMISTRY Kay Hardman-Rhyne

Research and development in ceramics for structural, optical, electronic,

magnetic, and other applications is being directed increasingly toward

improvements in processing science that will permit reproducible production

of defect-free materials. This goal requires extremely sophisticated

microstructural control. It is now recognized that the evolution of

microstructure begins at the very earliest stages .of processing, in the

chemistry of powder synthesis, and is carried forward in subsequent

compaction and densif ication to finished ceramic bodies. New approaches to

ceramic synthesis are evolving, based on advanced molecular-level synthetic,

mechanistic, and structural chemistry. Low-temperature synthetic procedures,

such as the "sol-gel” processes, are becoming increasingly important for

synthesis of advanced materials, often in heretofore unattainable

compositions. Advanced structural techniques, such as SANS and

high-resolution electron microscopy, are being utilized increasingly to

elucidate the pathways by which molecular structures evolve into ceramic

structures and microstructures.

The program of the Ceramic Chemistry Group is focused on research to

facilitate the application of modern chemical techniques and understanding to

improved processing of ceramics. The Group’s goal is essentially to put more

and better chemistry into ceramic processing. The objectives of the group

are to provide data, measurement methods, concepts, and standard materials

relating to chemical aspects of ceramics processing needed by industry for

predictive control of new processes and development of new materials.

Current emphasis is on advanced synthetic methods, evolution of structure in

ceramic synthesis, and relation of chemical process variables to particle

characteristics and microstructure.

Representative Accomplishments

• Preparation of micron particle size powder of TiB 2 using a novel low

temperature synthesis method for non-oxide compounds. A patent

application has been filed.

• Determination of the evolution of pores (including pore size and size

distributions) in Spinel (MgA^Ojj) "green" compacts and sintered

materials by small angle neutron scattering (SANS).

Low Temperature Synthesis of Ceramic Powders

J. J. Ritter, K. G. Frase, N. K. Adams

Synthesis of ceramic powders using molecular level reactions at low

temperature offers a number of advantages over conventional high temperature

processing. The starting reagents can be highly purified, and thus enhanced

product purity can be achieved. Dispersing the reagents in a solvent

provides mixing on the molecular level, rather than at the particulate level

as in solid state reaction. This molecular mixing increases homogeneity and

64
also affects the crystal structure. Powders prepared by low-temperature

routes are frequently fine-grained and more reactive than those prepared

conventionally, permitting reduction in sintering temperatures. Finally,

metastable compounds with particularly interesting properties not accessible

by solid state reaction can be often formed. Several new low temperature

synthetic methods have been developed for both oxide and non-oxide materials.

The high purity and homogeneity available via low temperature synthesis have

proved useful in the production of standard reference materials for

instrument calibration. Submicron particles of TiC>2 have been produced with

a homogeneous doping of 1 to 3 weight percent heavy metal (e.g. Zr , U. Pb) by

controlled hydrolysis of alkoxide precursors. These are being evaluated as calibration standards for analytical microscopes. Particle size distribution

can be controlled through the manipulation of the hydrolysis reaction

parameters

.

The effects of molecular level mixing and low temperature synthesis on crystallization product have been demonstrated in two ionic conductor

systems, sodium beta/beta"-alumina and YoTaOy. In both systems, the final

crystalline materials produced by alkoxide synthesis differ from the products

of solid state reaction.

In sodium beta/beta"-alumina, solid state reaction at temperatures above 1500

°C is required to reach the equilibrium phases, which are binary beta alumina

and ternary sodium beta"-alumina (Mg-stabilized) . By contrast, alkoxide

synthesis of materials with the beta"-alumina composition yield crystalline

products at 1100 °C which have a distorted "solid solution" beta-type

structure. The primary difference between the beta" and solid solution beta

structures is the Mg-substitution in the aluminum-oxygen layers. In the

beta" structure, this substitution is ordered (1), while in the solid

solution beta structure it is random. Thus the molecular mixing inherent in

alkoxide synthesis appears to favor the higher symmetry, disordered

structure

.

This preference for higher symmetry through alkoxide synthesis is also

observed in the case of Y^TaOy. When prepared by solid state reaction,

YoTaO-T forms as a distorted pyrochlore at temperatures between 1500 and 1700

°C. Above 1700 °C a cubic fluorite structure, like that of the oxygen ion

conducting cubic zirconia, forms which can be quenched into lower

temperatures. However, when prepared by alkoxide hydrolysis, the Y^TaOy

material begins to crystallize as the cubic phase at temperatures as low as 1000 °C. The tendency for disordered phases to form during low temperature

synthesis may lead to a new group of oxide ion conductors based on "high

temperature" disordered crystal structures.

Metal alkoxide chemistry is inappropriate for the synthesis of non-oxide

materials. Except for the polycarbosilane and aminosilane methods for SiC

and Si^Njj, the low temperature synthesis of non-oxide materials is largely

unexplored. Other chemistries are needed to synthesize fine powders of

materials such as TiB

2 and B^C.

65
A novel low temperature synthesis of these non-oxide compounds adapts the

Wurtz-Fittig reaction, common in organic chemistry. Metal chlorides react

with sodium in a non-polar solvent to produce an amorphous precursor powder

and NaCl. The NaCl can be distilled off and the precursor crystallized at

temperatures as low as 900 °C:

1 0Na + TiCljj + 2BC1

3

-» "TiB 2

" + 10 NaCl -»• TiB2

+ 10 NaCl(g)

heptane vacuum

25-160 °C 900 °C

It is proposed that the initial reaction involves halogen abstraction from

each of the metal halides and a coupling of the resultant products:

BC1

3

+ TiCljj + 2 Na -»• Cl 2 B-TiCl

3

+ 2 NaCl

Further halogen abstraction and coupling reactions generate a three-dimensional B-Ti precursor matrix denoted as "TiB2

" in the above

equation. Titanium carbide and B^C have been generated from TiCl^, BC1

3 and

CClii in similar reactions.

Pore Size and Size Distribution In Spinel

K. A. Hardman-Rhyne, K. G. Frase

The problem of measuring the evolution of pore size distribution during

sintering has long challenged material scientists. A non-destructive

small-angle neutron scattering (SANS) technique, sensitive to defects (size

up to 3 pm) and their size distribution has been developed at NBS and applied

to porosity by K. A. Hardman-Rhyne and K. G. Frase.

SANS has been used to examine the sintering process using both unfired

compacted powder samples ("green" ceramics) with 50 percent porosity and

sintered materials with 2 percent porosity (generally consisting of closed

pores). Both volume fraction and pore size (-1.0 pm) are much larger than

can be seen with traditional single particle diffraction techniques in small

angle scattering. Multiple scattering techniques have been developed at NBS

and employed to elucidate microstructural information including pore size,

size distribution, porosity, and surface areas. The analysis procedure

utilizes the strong wavelength dependence of the small Q incoherent multiple

scattering data to determine the scattering radius of curvature, r

c at Q=0.

In addition, a Porod analysis is used to determine the total surface area of

the pores from the large Q data. The SANS results are compared to data from

other techniques such as SEM, mercury porosity, and BET, in which closed

porosity is not detected.

Compacts of submicron spray-dried spinel (MgA^Oj,) powder (approximately

0.76 pm in size) were uniaxially pressed at 69 GPa and then isostatically

pressed at 207 GPa. The "green" pressed disks were calcined at 700 °C to remove organic binders and will be referred to as the "green" state (G.S.)

sample. One G.S. sample was fired at 1300 °C for 12 hours to obtain a partially sintered material, referred to here as the sintered sample.

66
The small-Q regime of the scattering curves were fitted to a Gaussian

function and the incident beam scattering was subtracted to obtain r

Q [Q] (the

notation means radius of curvature at the origin in Q units) as a function of

wavelength. The R

ef

. f

(0) or effective void radius measured from the small-Q

data for the G.S. and sintered samples is 400 and 800 nm, respectively. The

R

e ff(») or effective void radius measured by the large-Q data and surface

area of the voids was determined from the analyses of the Porod regime. The

R

e ff(®) for the G.S. sample is 160 nm and for the sintered material, 690 nm. The surface area for the G.S. sample is 4.5 m

2 /gm, which is in good agreement

with gas adsorption results.

The two R

e ff values obtained for the " green" state could suggest a distribution of void sizes, but the large difference here suggests that two

different size characteristics are being measured; that of "neck" and

"bottles" of ink-bottle type connected porosity. In the sintered material

the SANS measures both closed and open porosity. With the completion of the

cold source at the reactor this year, higher wavelengths will be available

which will allow measurements of pores or inclusions up to 30 urn. This is

particularly significant in that the size range of 5 to 30 ym will allow SANS

results to be compared with other NDE techniques such as thermal waves and

ultrasonics which can be used as sensors for on-line process control.

Structural Evolution in Low-Temperature Ceramic Processing

T. D. Coyle, K. Hardman-Rhyne

Although low-temperature synthesis of ceramic powders and glasses offers

numerous advantages, its use has been largely empirical. A new research

program has been initiated to elucidate the fundamental reaction mechanisms

by which structure evolves in low temperature processing from molecular

precursors to glass or crystalline products in multicomponent systems. The

objective of the work is to define the critical chemical parameters that will

permit predictive control of powder, film and glass processing. Current

research emphasizes processes for synthesis from metal-organic precursors of

multicomponent oxide-systems of interest as electronic or dielectric

materials. Molecular structure and kinetics are being studied

spectroscopically (FTIR, NMR); the polymerization of molecular species to

amorphous ceramic precursors and densif ication of sol-gel derived materials

is being evaluated by SANS methods; and crystallization of amorphous

precursors is being studied by conventional x-ray diffraction techniques.

A project has been initiated in cooperation with the Ceramic Characterization

Group to prepare silica powders (doped at low levels with alkalis, alkaline

earths, and transition elements) from alkoxide precursors and to investigate

crystallization behavior of these. The objective is to understand the

effects of dopants on crystallization of sol-gel derived amorphous silica and

to generate crystalline tridymite-containing materials for application as quantitative x-ray powder diffraction standards for quality control in the

refractories industry and for use in environment measurements. Amorphous

silica powders with highly uniform particle size in the 0.2 micron range

(which may be useful as SEM resolution standards) have been obtained, ind

doping and crystallization studies are in process.

67
Collaborative work with MIT has begun on concentrated colloidal suspensions

using small angle neutron scattering; this represents an area that will be

expanded in the future.

68
OUTPUTS AND INTERACTIONS

SELECTED RECENT PUBLICATIONS

Mechanical Properties Group

Chuck, L.; Fuller, Jr., E. R.; Freiman, S. W. Chevron-notch bend

tesing in glass: some experimental problems. Am. Soc. Testing Mater.

(U.S.) Special Tech. Publ. 855; 1984. 167 p.

Cook, R. F.; Lawn, B. R. Controlled indentation flaws for

construction of toughness and fatigue master maps. Freiman, S. W.

,

ed. Methods for assessing the structural reliability of brittle

materials. Am. Soc. Testing Mater. (U.S.) Spec. Tech. Publ. 844;

1984. 20 p.

Cook, R. F.; Lawn, B. R. Controlled indentation flaws for

construction of toughness and fatigue master maps. J. of Research of

the National Bureau of Standards, 89(6): 453-465; 1984.

Dabbs, T. P.; Fairbanks, C. J.; Lawn, B. R. Subthreshold

indentation flaws in the study of fatigue properties of ultra-high

strength glass. Freiman, S. W. , ed. Methods for assessing the

structural reliability of brittle materials. Am. Soc. Testing Mater.

(U.S.) Spec. Tech. Publ. 844; 1984. 11 p.

Gonzalez, A. C.; Multhopp. H.; Cook, R. F; Lawn, B. R.;

Freiman, S. W. Fatigue properties of ceramics with natural and

controlled flaws: a study on alumina, in Methods for assessing the

structural reliability of brittle materials. S. W Freiman, ed. Am.

Soc. Testing Mater. (U.S.) Spec. Tech. Publ. 844; 1984. 13 p.*

Krause, K. , Jr.; Fuller, E. R., Jr., Fracture toughness of polymer

concrete materials using various chevron-notched configurations. Am.

Soc. Testing Mater. (U.S.) Spec. Tech. Publ. 855; 1984. 309 p.

Lawn, B. R.; Jakus, L.; Gonzalez, A. C. Sharp vs blunt crack

hypotheses in the strength of glass: a critical study using

indentation flaws. J. of Am. Ceram. Soc. 68(1): 25-34; 1985.

Multhopp, H.; Lawn, B. R.; Dabbs, T. P. Deformation-induced crack

initiation by indentation of silicate materials, in Deformation of

ceramic materials II. R. E. Tressler and R. C. Bradt, eds. New York,

NY: Plenum Publishing Corporation; 1984. 681-693.

Tighe, N. J.; Wiederhorn, S. M.; Chuang, T. J.; McDaniel, C. L. Creep

cavitation and crack gowth in silicon nitride, in deformation of

ceramic materials II. R. E. Tressler and R. C. Bradt, eds. New York,

NY: Plenum Publishing Corporation; 1984.

Tighe, N. J. Microstructural Analysis of Creep Failure in SiNq and

SiC, in microbeam analysis. A. D. Ramig J and J. I Goldstein, eds.

127-130.

69
Tighe, N. J.; Hardman-Rhyne , K. A.; Lu, Y. N. Characteristic

Cavitation and Microcracks in «-SiC, Si^, and Zr02

. Proceedings of

the Cocoa Beach, Florida american ceramic society conference, Am.

Cer. Soc.; Cocoa Beach, FL.; 1985.

Wiederhorn, S. M.; Freiman, S. W. ; Fuller, Jr., E. R.; Richter, H.

Effect of multiregion crack growth on proof testing. Proceedings of

ASTM symposium on methods for assessing the structural reliability of

brittle materials. Amer. Soc. Testing Mater. (U.S.) Spec. Publ. 844;

1984. 21 p.

Glass and Composites Group

Birnbaum, G. ; White, G. S. Laser techniques in NDE in research

techniques in nondestructive testing; in press.

Chuck, L.; Fuller, Jr., E. R.; Freiman, S. W. Chevron-notch bend

tesing in glass: some experimental problems. Am. Soc. Testing Mater.

(U.S.) Special Tech. Publ. 855; 1984. 8 p.*

Freiman, S. W. ; Baker, T. L.; Wachtman, J. B., Jr. A computerized

fracture mechanisms database for oxide glasses. Nat. Bur. Stand.

(U.S.) Tech. Note 1212; 1985.

Freiman, S. W. ; White, G. S.; Fuller, E. R., Jr. Environmentally

enhanced crack growth in soda-lime glass. J. Am. Ceram. Soc. 68(3):

108 - 112 ; 1985 .

Freiman, S. W. Brittle solids: Fracture toughness testing methods,

chapter in Encyclopedia of materials science and engineering. New

York, NY: Pergamon Press; in press.

Freiman, S. W. Environmentally enhanced crack growth in glasses. NATO

Publication; in press.

Gonzalez, A. C.; Multhopp. H.; Cook, R. F; Lawn, B. R.; Freiman, S. W.

Fatigue properties of ceramics with natural and controlled flaws: a study on alumina, in Methods for assessing the structural reliability

of brittle materials. S. W Freiman, ed. Am. Soc. Testing Mater. (U.S.)

Spec. Tech. Publ. 844; 1984. 13 p.

Lawn, B. R.; Jakus, L.; Gonzalez, A. C. Sharp vs blunt crack

hypotheses in the strength of glass: a critical study using

indentation flaws. J. of Am. Ceram. Soc. 68(1): 25-34; 1985.

Scarfe, C. J.; Cronin, D. J.; Wenzel, J. T.; Kauffman, D. A.

Viscosity-temperature relationships at 1 atm in the system diopside

anorthite. Am. Mineral.; in press.

White, G. S.; Greenspan, D. C.; Freiman, S. W. Corrosion and crack

growth in 33 percent Na 2 o-67 percent Si0 2 and 33 percent

Li 2 0-67 percent Si0 2 glasses. J. Amer. Ceram. Soc.; in press.

70
Tribology Group

Clark, D. B.; Klaus, E. E.; Hsu, S. M. The role of iron and copper in

the oxidation degradation of lubricating oils. J. Lubrication

Engineering. 41(5): 280-287; 1985.

Hsu, S. M. Discussion on thermal and oxidative stabilities of liquid

lubricants. Tribology in the 80's, NASA CP2300, 457, 1984.

Hsu, S. M. Lubricants, chapter in Encyclopedia of materials science

and engineering. Bever, M. , ed. New York, NY: Pergamon Press, 1985.

Hsu, S. M. ; Ku, C. S.; Pei, P. Oxidation mechanisms of lubricant.

Presented at the ASTM Oxidation Symposium; 1983 December; Miami, FL;

in press.

Hsu, S. M. ; Gates, R. S.; Jewett, K. A study on the nature of boundary

lubricating film. Part II. static simulation and dynamic wear tests.

ASLE Annual Meeting; 1984 Chicago, IL; in press.

Ku, C. S.; Hsu, S. M. Thin-film oxidation test: relationship between

composition and additive response for re-refined oils. ACS annual

meeting; 1984 August; Philadelphia, PA. Symposia of division petroleum

chemistry, Amer. Chem. Soc. 29(4): 1066-1074; 1984.

Ku, C. S.; Klaus, E. E.; Hsu, S. M. A study of additive response 'in a series of re-refined base oils typical of current commercial practice.

Proceedings of congress international de tribologie, Elsevier, 1985.

Munro, R. G. ; Block, S.; Piermarini, G. J.; Mauer. F. A. Diamond anvil

cell technology for P,T studies of ceramics: Zr0 2 8 mol.? Y2 O 0 . Proceedings of the symposium on emergent process methods for high

tech, ceram. Materials Science Research 17: 783; 1984.

Munro, R. G. ; Block, S.; Piermarini, G. J. On the reliability of the

isothermal bulk modulus deduced from model equations of state, J.

Appl . Phys. 56: 2174; 1984.

Munro, R. G. ; Block, S.; Piermarini, G. J.; Holzapfel, W. B. Model

lineshape analysis for the ruby R-lines, J. Appl. Phys. 56: 165; 1985.

Munro, R. G. Temperature considerations in the study of surfaces using

a four-ball wear apparatus. J. Appl. Phys. 57: 4950; 1985.

Optical Properties Group

Feldman, A.; Farabaugh, E. N. Densif ication of zirconia films by

coevaporation with silica, in OM85 Basic properties of optical

materials summaries of papers, Nat. Bur. Stand. (U.S.) Spec.

Publ. 697; 1985. 4 p.

Feldman, A., ed. 0M85 Basic properties of optical materials, summer

i

of papers. Nat. Bur. Stand. (U.S.) Spec. Publ. 697 (Topical conf-r-.-r. •• on basic properties of optical materials); 1985 April. 294 p.

71
Frederikse, H. P. R.; Kahn,. A. H.; Dragoo, A. L.; Hosier, W. R.

Electrical resistivity and microwave transmission of hexagonal boron

nitride. J. Am. Cer. Soc.; 68(3): 131-135; 1985.

High Temperature Chemistry Group

Bonnell, D. W. ; Montgomery, R. L.; Stephenson, B.;

Sundareswaren, P. C.; Margrave, J. L. Levitation calorimetry, in

Specific heat of solids, chapter 7. McGraw-Hill; in press.

Bonnell, D. W. ; Hastie, J. W. Vaporization of simulated nuclear waste

glass. J. Non-Cryst. Solids 1985; in press.

Cook, L. P.; Hastie, J. W. Solid-liquid-vapor interactions in

alkali-rich slags. Vorres, K., ed. Proceedings of symposium on chemistry of mineral matter and ash in coal; American Chemical

Society; 1985; in press.

Hastie, J. W. New techniques and opportunities in high temperature

mass spectrometry. Pure and Applied Chem. 56: 1583; 1984.

Hastie, J. W. ; Bonnell, D. W. ; Schenck, P. K. A laser-induced

vaporization of refractory materials. NBSIR 84-2983; 1984.

Hastie, J. W. ; Bonnell, D. W. A predictive phase equilibrium model for

multicomponent oxide mixtures Part II: oxides of Na-K-Ca-Mg-Al-Si.

High Temp. Science, 19:275; 1985.

Hodeau, J. L.; Marezio, M. Santoro, A.; Roth, R. S. Neutron

diffraction structure determination of the high-temperature form of

lithium tritantalate, HL-LiTa^Oo. J. of Solid State Chem. 51: 275-292;

1984.

Ritter, J. J.; Roth, R. S.; Blendell, J. Alkoxide precursor synthesis

and characterization of phases in the barium titanium oxide system. J.

Amer. Ceram. Soc.; 1985; in press.

Travis, J. C.; Turk, G. C.; DeVoe, J. R.; Schenck, P. K.; van Kijk, C.

A. Principles of laser enhanced ionization spectrometry in flames.

Prog, in Anal. Atomic Spect. 7: 199; 1984.

Structural Chemistry Group

Block, S.; da Jornada, J. A. H.' Piermarini, G. J. The P-T phase

diagram of zirconia. J. Amer. Ceram. Soc, (68); 1985.

da Jornada, J. A. H.; Block, S.; Piermarini, G. J. Interferometric

high pressure gauge for the diamond anvil cell useful at high

temperatures. Applied Physics Letters 45(6): 700-702;

1984 September 15.

72
da Jornada, J. A. H.; Block, S.; Mauer, F. A.; Piermarini, G. J. Phase

transition and compressio of LiNbOo under static very high pressure.

J. Appl Phys. 57(3): 842-844; 1985 February.

Miller, P. J.; Piermarini, G. J.; Block, S. A FT-IR microspectroscopic

method for kinetic measurements at high temperatures and high

pressures. J. Applied Spectroscopy; in press.

Munro, R. G. ; Block, S.; Piermarini, G. J.; Mauer. F. A. Diamond anvil

cell technology for P,T studies of ceramics: Zr0 2

8 mol.? Y2 O 3

. Proceedings of the symposium on emergent process methods for nigh

tech, ceram. Materials Science Research 17: 783; 1984.

Munro, R. G. ; Block, S.; Piermarini, G. J. On the reliability of the

isothermal bulk modulus deduced from model equations of state, J.

Appl. Phys. 56: 2174; 1984.*

Munro, R. G. ; Block, S.; Piermarini, G. J.; Holzapfel, W. B. Model

lineshape analysis for the ruby R-lines, J. Appl. Phys. 56: 1 6 5

;

1985.*

Ceramic Powder Characterization Group

Kupperman, D. S.; Karplus, H. B.; Poepper, R. B.; Ellingson, W. A.;

Berger, H.; Robbins, C. R.; Fuller, E. R., Jr. Application of NDE

methods to green ceramics: initial results. Proceedings "Applications

and development of NDE for use in materials processing. Amer. Soc.

Mech. Engr.; 1983 October. Philadelphia, PA. in press.

Robbins, C. R.; Hasselriis, F. Characterization of slag and fouling

residues from co-combustion of powdered refuse-derived fuel with

residual oil and comparison with coal and RDF residues, chapter in

Resource recovery from municipal, hazardous, and coal solid wastes.

New York, NY: Plenum Press; 1983; in press.

Surface Chemistry and Bioprocesses Group

Brinckman, F. E. Environmental inorganic chemistry of main group

elements. Irgolic, K. J. and Martell, A. E., eds. Proc. U.S. Italy

workshop on environmental inorganic chemistry; 1983 June; San Miniato,

Italy. VCH Publisher, Dearfield Beach, FL; 1985. 195-238.

Brinckman, F. E.; Olson, G. J.; Thayer, J. S. Biological mediation of

marine metal cycles: the case of methyl iodide, in Marine and

estuarine geochemistry. A. Sigleo and A. Hattori, eds. Honolulu,

Hawaii: Lewis Publishers; 1985. in press.

Brinckman, F. E.; Olson, G. J. Chemical principles underlying

bioleaching of metals from ores and solid wastes and bioaccumulat icn

of metals from solution. Biotechnol. Bioengin.; in press.

73
Laughlin, R. B.; Johannessen, R. B.; French, W. ; Guard, H. E.;

Brinckman, F. E. Structure-activity relationships for organotin

compounds. Environ. Toxicol, Chem. 4: 343 - 351 ; 1985.

Lockhart, T. P.; Manders, W. F.; Brinckman, F. E. Spin coupling

through oxygen. Influence of structure and solvent on 2 J( 1

1

9gn, 1

1

?Sn)

in the 1

1

^Sn nmr of hexaorganodistannoxanes. J. of Organometallic

Chemistry 286: 153*158; 1985.

Lockhart, T. P. Steric effects in neophyltin(IV) chemistry. J. of

Organometallic Chemistry 287: 179*186; 1985.

Lockhart, T. P.; Manders, W. F.; Zuckerman, J. J. Structural

investigations by solid state ^3 c nmr. Dependence of M J( 1

1

^Sn, 1 3c) on Me-Sn-Me angle in methyltin(IV)s. J. Amer. Chem. Soc. 107:

11546-4547; 1985.

Lockhart, T. P.; Manders, W. F. Structural analysis of methyltin(IV)

polymers by solid-state 1 3c nmr spectroscopy. J. Am. Chem. Soc.; in

press.

Manders, W. F.; Lockhart, T. P. High resolution 1 3 q CPMAS NMR of

methyltin solids. Observation of J coupling to tin. J. Organomet.

Chem.; in press.

Olson, G. J.; Iverson, W. P.; Brinckman, F. E. Disfigurement of

external paint films by algae and bacteria and quantitative detection

by epifluorescence microscopy. Proceedings of the 6th International

Biodeterioration Symposium; in press.

Olson, G. J. Microbial intervention in heavy element containing

industrial process streams and waste products, in The Importance of

chemical speciation in Environmental Process. Bernard, M.

;

Brinckman, F. E„, eds. W. Berlin: Spr inger-Ver lag; in press.

Parks, E. J.; Blair, W. R.; Brinckman, F. E. Determination of GFAA of

organotins in sea water, using enhancement methods. Talanta, 32(8A):

633-639; 1985.

Thayer, J. S.; Olson, G. J; Brinckman, F. E. Iodomethane as a potential metal mobilizing agent in nature; Environ. Sci. Technol. 18:

726-729; 1984.

Structure Science Group

Chuck, L.; Fuller, Jr., E. R.; Freiman, S. W. Chevron-notch bend

tesing in glass: some experimental problems. Am. Soc. Testing Mater.

(U.S.) Special Tech. Publ. 855; 1984. 167 p.*

Freiman, S. W. ; White, G. S„; Fuller, E. R., Jr. Environmentally

enhanced crack growth in soda-lime glass. J. Am. Ceram. Soc. 68(3):

108-112; 1985.*

74
Handwerker, C. A.; Cahn, J. W. ; Yoon, D. N.; Blendell, J. E.

Proceedings of a symposium, atomic transport in alloys: recent

developments, Murch and Dayavada, eds. TMS Publications, 1985.

Knab, L. I.; Walker, H. N.; Clifton, J. R.; Fuller, E. R., Jr.

Fluorescent thin sections to observe the fracture zone in mortar.

Cement and Concrete Research. 14: 339-344; 1984.

Knab, L. I.; Fuller, E. R., Jr. Nature of crack-tip process zone in

mortar and concrete subject to cyclic fatigue. Proceedings of

international symposium on fundamental question and critical

experiments on fatigue; 1984 October 18-20; Arlington, TX. in press.

Krause, K. , Jr.; Fuller, E. R., Jr., Fracture toughness of polymer

concrete materials using various chevron-notched configurations. Am.

Soc. Testing Mater. (U.S.) Spec. Tech. Publ. 855; 1984. 309 p.*

Kupperman, D. S.; Karplus, H. B.; Poepper, R. B.; Ellingson, W. A.;

Berger, H.; Robbins, C. R.; Fuller, E. R., Jr. Application of NDE

methods to green ceramics: initial results. Proceedings "Applications

and development of NDE for use in materials processing. Amer. Soc.

Mech. Engr.; 1983 October. Philadelphia, PA. in press.*

Lawn, B. R.; Fuller, Jr., E. R. Measurements of thin-layer surface

stresses by indentation fracture. J. of Matls. Sci. 19: 4061-4067;

1984.*

Michalske, T. A.; Fuller, E. R., Jr. Closure and repropagation of

healed cracks in silicate glass. J. Amer. Ceram. Soc.; 1985.

Ritter, J. J.; Roth, R. S.; Blendell, J. Alkoxide precursor synthesis

and characterization of phases in the barium titanium oxide system. J.

Amer. Ceram. Soc.; 1985; in press.

Yoon, D. K. ; Cahn, J. W. ; Handwerker, C. A.; Blendell, J. E.;

Paik, S. J. ASM Symposium on Interfacial Migration, 1985.

Ceramic Chemistry Group

Berk, N. F.; Hardman-Rhyne , K. A. Characterization of alumina powder

using multiple small angle neutron scattering, I: theory. J. of Appl.

Cryst.; in press.

Berk, N.F.; Hardman-Rhyne, K. A. The phase shift and multiple

scattering in small angle neutron scattering: application to beam

broadening from ceramics. Physica B; in press.

Coyle, T. A. Encyclopedia of glass, ceramics, and cement: John Wiley

and sons; 1985. 778-796.

Hardman-Rhyne, K. A.; Berk, N. F. Ceramic material character izat ion

using small angle neutron scattering techniques. Proceedings of Vrv- thirty-first sagamore Army materials and mechanics research

conference; August 1984; Plenum Press, New York; 1985; in press.

75
Hardman-Rhyne , K. A.; Berk, N. F. Characterization of alumina powder

using multiple small angle neutron scatter, II: experiment. J. of

Appl. Cryst.; in press.

Hardman-Rhyne, K. A.; Frase, K. G. ; Berk, N. F. Applications of

multiple small angle neutron scattering to studies of ceramic

processing. Physica B; in press.

Ritter, J. J.; Roth, R. S.; Blendell, J. Alkoxide precursor synthesis

and characterization of phases in the barium titanium oxide system. J. Amer. Ceram. Soc.; 1985; in press.

Ritter, J. J.; Frase, K. G. Low temperature synthesis of ceramic

precursor powders for electronic and structural applications.

Proceedings of the 2nd international conference on ultrastructure;

1985 March; Palm Coast, FL. John Wiley & Sons; 1985; in press.

76
SELECTED TECHNICAL/PROFESSIONAL COMMITTEE LEADERSHIP

American Ceramic Society

Committee on Publications

Subcommittee on "Phase Diagrams for Ceramists"

R. S. Roth, Chairman

Glass Division

S. W. Freiman, Chairman

Committee on Glass Standards Classification and

Nonmenclature

M. J. Cellarosi, Chairman

Editorial Committee

B. R. Lawn, Chairman

S. M. Wiederhorn, Subchairman

A. L. Dragoo, Subchairman

Phase Equilibria Data Center Advisory Committee

L. P. Cook, Chairman

American National Standards Institute (ANSI)

Committee 43.1 —Safety Standards for X-ray Diffraction and

Fluorescence Analysis Equipment

S. Block, Chairman

American Physical Society Editorial Board

Review of Scientific Instruments

P. K. Schenck

American Society for Metals

Executive Committee—Washington Chapter

N. J. Tighe

American Society for Testing and Materials

Cl 4: Glass and Glass Products

M. J. Cellarosi, Chairman

Cl 4.01: Nomenclature of Glass and Glass Products

M. J. Cellarosi, Chairman

FI : Electronics

FI : 02 : Laser

A. Feldman, Subcommittee Editor

American Society of Lubrication Engineers

Annual Meeting Program Committee

S. M. Hsu, Secretary

Committee on Wear

S. M. Hsu, Chairman

COMAT Subcommittee on Ceramics

S. M. Hsu, Member

Gordon Research Conference on Tribology

S. M. Hsu, Vice Chairman

77
High Temperature Science Editorial Advisory Board

J. W. Hastie

Interagency Coordinating Committee on Ceramics

S. M. Hsu, Member

International Commission for Optics

U. S. National Committee

B. Steiner, Chairman

International Union of Crystallography (IUCr)

Commission on Crystallographic Studies at Controlled

Pressures and Temperatures

G. J. Piermarini, Chairman

International Union of Pure and Applied Chemistry

Commission II— 3 : High Temperature and solid State Chemistry

J. W. Hastie, U.S.A. Associate Member

JCPDS-International Centre for Diffraction Data

C. R. Hubbard, Vice-Chairman

NAS Assessment Committee on Ceramic Tribology

S. M. Hsu, Member

Oak Ridge National Laboratory

High Temperature Materials Laboratory Advisory Committee

S. M. Wiederhorn

Off-Road Machinery Technology Steering Committee, Wear Task Group

S. M. Hsu, Member

Optical Society of America

1985 Annual Meeting Local Arrangements Committee

B. Steiner, Chairman

78
INDUSTRIAL AND ACADEMIC INTERACTIONS

In 1985, the Division performed collaborative research with over 50

private organizations through its Industrial Research and Guest Worker

programs and other joint arrangements. Representative examples of such

interactions include:

INDUSTRIAL

1 . AT&T Bell Laboratories

Research on the crystallographic characterization of ionic ceramic

conductors is being carried out in a collaborative program between

R. J. Cava and D. W. Murphy of Bell Laboratories and A. Santoro

(Reactor Division) and R. S. Roth. Lithium inserted oxides are prepared at Bell Labs and characterized at NBS using the neutron

diffraction total profile (Rietveld) analysis. The neutron diffraction data and analysis techniques uniquely locates the position of

the lithium ion in the structure. Current emphasis of the joint work

is on alkali niobium-tungsten-vanandium oxide phases having the

pyrochlore type structure.

2. Atlantic Mining Company

The Surface Chemistry and Bioprocessing Group is carrying on a research collaboration with AMC to characterize biological processes

potentially useful for recovery of previous and strategic metals from

certain major domestic deposits, low grade pyritic ores. These ores

are not amenable to conventional processing due to matrix effects and

low grade nature of the deposits. In addition to selective

bioextraction of noble metals, platinum and gold for example, new bioreactor designs are being evaluated for improving iron

processing.

3. Battelle Memorial Institute

B. Steiner has worked closely with Battelle Memorial Institute in

identifying areas for close technical collaboration in support of a multiclient program that Battelle is assembling to develop

electrooptic technology for optical communications. Initial research

has begun in collaboration with the Center for Analytical Chemistry

in the analysis of single crystals of lithium niobate. Parallel

synchrotron topographic studies will be initiated shortly.

4. Crystal Technology, Inc.

B. Steiner and the Synchrotron Group of the Metallurgy Division h

collaborated with Crystal Technology on monochromatic topographic

examination of specially grown lithium niobate single crystals lurir.v

the first two weeks of dedicated x-ray ring operation at the Nat: •

. Synchrotron Light Source. Crystals grown under various conditions

display highly growth-dependent defects and strains. Such dnf-- can affect the fabrication of complex communications and computing

79
devices made from these crystals. Correlation of the topographic

information with parametric variation in the crystal growth process

will help to separate those defects associated with the initial

crystal growth from those associated with subsequent diffusion to

form waveguides in the crystal.

5. Cummins Engine Company

Cooperative research between the Tribology Group and Gordon Starr

(Cummins) involves ceramic tribology related to heat engine development. Research centers on the mechanism of failure, surface topography effects, and microstructural influence on wear of ceramic

coatings and parts.

6. General Motors

Cooperative research between N. Hakim (GM) and S. Hsu is being

carried out on the lubrication mechanism of ceramic parts in engine

contacts.

7. American Ceramic Society

(Ceramics Industry)

The High Temperature Chemistry Group interacts with the Ceramics

Industry, through the Joint NBS/ACerS Phase Diagrams for Ceramists

Program. The ceramics industry provides information to NBS on phase

diagram needs and priorities through their participation in

ACerS-NBS Committees and through direct interactions (visits) between

industrial and NBS management and technical personnel. The industry

is also funding a Ceramic Society program for Research Associateships

to expand the NBS Data Center on ceramic phase diagrams. The Ceramic

Society publishes and disseminates the Data Center outputs which have

included five hard-cover volumes containing 6500 evaluated phase

diagrams, and which in the future will also include on-line computer

services to industry.

8. American Iron and Steel Institute (AISI) and Cleveland Cliffs Iron

Company

The Surface Chemistry and Bioprocesses Group is collaborating with

Cleveland Cliffs Iron Company (William Hancock, Research Coordinator)

in examining upgrading of ores and concentrates via biological

phosphorus, silicon, and sulfur removal.

9. Joint Committee for X-ray Powder Diffraction Standards

(JCPDS) —International Centre for Diffraction Data

For nearly 30 years this cooperative program with industry (JCPDS)

has served as the focal point for the provision of high quality

reference powder patterns for inclusion in the JCPDS' s Powder

Diffraction File. Under an expanded relationship with JCPDS, the

program at NBS now includes critical evaluation of published data,

development of a numerical data base, and research on producing

accurate data and on the use of these data in phase identification.

80
The JCPDS publishes the well known Powder Diffraction File, the

oldest numerical data compilation for analytical purposes in the

world (over 20 different publications covering powder and single

crystal diffraction data are offered). The Ceramic Powder Characterization Group provides overall technical guidance to the research

associates sponsored by JCPDS in the provision of reference patterns;

promotes and coordinates the activities of the research associates

with other data centers; and develops standard reference materials

for calibration of x-ray diffraction equipment. The JCPDS disseminates the data through numerous mechanisms.

JOINT INDUSTRIES/UNIVERSITIES

1. AT&T Bell Laboratories, Trans Tech Division of Alpha Industries,

University of Pennsylvania and Arizona State University

A joint program on dielectric ceramics having important microwave

applications is being carried out by R. S. Roth, J. J. Ritter,

W. Coblenz, and J. Blendell in association with R. J. Cava,

H. O’Bryan (Bell Labs), T. Negas (Alpha Industries), P. Davies (U. of

Pennsylvania) and A. Olsen (Arizona State U.). Powders of barium

poly-titanates (pure and doped) are synthesized from alkoxide

precursors, conditioned, compacted and densified at NBS with phase

equilibria and crystal chemistry determined at each processing step.

Characterization of microwave properties (dielectric constant, Q,

TCK, etc.,r) is performed on NBS prepared powders and compacts by the

Industrial organizations. The University groups investigate the

materials using high resolution electron microscopy lattice imaging

techniques, correlating observed and calculated lattice image defects

with the dielectric and thermodynamic properties.

2. General Electric and Rice University

NBS participates in a joint program with NASA for materials

processing in space. D. W. Bonnell (High Temperature Processes

Group) plans, supervises, and participates in experiments jointly

with personnel from GE and Rice University at the King of Prussia

laboratory (PA). These experiments involve use of a state-of-the-art

facility designed by Dr. Bonnell for levitation melting of tungsten

and other refractory metals coupled with drop calorimetry. The

results, in addition to providing basic thermodynamic information

indicate the limitations of ground-based versus space experiments.

UNIVERSITIES

1 . Johns Hopkins Unviversity

Robert Kelly of the Chemical Engineering Department and

G. J. Olson and F. E. Brinckman are conducting joint research

on microbial attachment to and solubilization of strategic metal or-: characterized by non-destructive surface analysis techniques

including epifluorescence microscopy and FTIR.

81
2. Massachusetts Institute of Technology (MIT)

Joint work with R. Coble (MIT), C. Handwerker (Metallurgy Division),

J. Blendell, K. Rhyne, and K. Frase, involves the characterization of

flaws (pores) in alumina ceramics, by SANS and conventional

microstructural techniques. Samples having different porosities are prepared at MIT and analyzed at NBS with the goal of correlating pore

size distributions with SANS data; an important result will be the

effect on pore size distribution caused by polishing and etching.

3. Northwestern University

Joint research involves lubrication modeling between S. Hsu and

Prof. Herbert Cheng. The research focuses on the

microelastohydrodynamic theories under wearing conditions. This is

the first attempt at combining surface chemistry with surface

mechanics to create a predictive wear model.

4. Pennsylvania State University

The Phase Diagrams for Ceramists Data Center has an ongoing

contractual/collaborative interaction with K. Spear of the Materials

Science Department. He is developing the mathematical basis and

computer software for including NBS developed solution models into

phase diagram optimization/prediction codes. At the present time,

° existing computer codes for phase diagram modeling, developed for

relatively simple alloy and molten salt systems, are not applicable

to the more complex ceramic systems, e.g., oxides. This technical

advance is necessary to the successful implementation of the

NBS/ACerS five year development program for a computerized ceramic

phase diagram data base.

The Tribology Group has several joint research projects with the

Department of Chemical Engineering and the Materials Research

Laboratory at PSU. The principal collaborators are S. Hsu, R. Munro,

and R. Gates of NBS and Prof. E. Klaus, Prof. L. Duda,

Prof. N. Macmillan, D. Deckman, and J. Yellets of PSU. The research

projects include fundamental studies on the vapor phase lubrication

of ceramic materials at high temperature; microstructural effects in

ceramic wear processes; high temperature friction and wear tribometer

design; and ceramic wear modeling which seeks to establish a theoretical understanding of ceramic wear processes.

5. Rensselaer Polytechnic Institute

G. J. Olson and F. E. Brinckman are collaborating with Professor

Henry L. Ehrlich on mechanisms of silver ore solubilization and

resistance in metal ore processing bacteria.

6. Rice University

D. W. Bonnell interacts with J. L. Margrave of the Chemistry

Department at Rice University for the purpose of developing (and

applying) state-of-the-art levitation calorimetric techniques. These

techniques are needed for the determination of basic thermodynamic

32
quantities of refractory materials (e.g., W, Ta, carbides) in their

solid and liquid states. The collaborative effort is sponsored by

the NASA Materials Processing in Space Program, and General Electric

is a third member of this Government-University-Industry team.

7. Rutgers University

Joint work with J. Blum (Rutgers) and J. Blendell involves production

of seeded sol-gel glasses to be used in studies of phase controlled

crystallization at NBS.

8. University of California, Lawrence Livermore National Laboratory

Joint work with M. Weber (LLNL) and D. Blackburn and W. Haller

involves the luminescent behavior of various elements in glass

matrices. Matrix composition and processing conditions affect such

parameters as emission wavelength, band width, life time and quantum

yield which are of importance to glass lasers and optical frequency

convertors. Oxide and non-iron-oxide glasses with emitting elements

are developed at NBS and characterized for glass forming and element

loading capability. LLNL measures optical parameters, and the

results are correlated to glass composition. The goal of this work

is to improve the understanding of luminescence and may lead to novel

types of lasers.

In another joint work between NBS and LLNL, W. Haller collaborated

with T. Bernat, D. Miller and other members of LLNL in the

development of high pore volume aerogels. Aerogels of this type are

used to study equation of state behavior under extreme conditions.

9. University of Cincinnati

Scientific collaboration with Prof. John S. Thayer on molecular

mechanisms of metal solubilization and transformation by biogenic

metabolites is being pursued. G. J. Olson and F. E. Brinckman are co-authoring patent with Thayer on using biogenic methyl iodide as a novel metal ore extraction process.

10.

University of Maryland

Members of the Surface Chemistry and Bioprocesses Group are collaborating with Prof. Michael Bellama and his doctral students on biological and chemical transformations of organometallic materials

in environmental situations.

J. Iriate of the University of Maryland and J. Ritter have been

collaborating on problems related to the synthesis of barium

titanates precursors from mixed alkoxides. The work is important to

the industrial development of ceramics having tailored propert ;*3 f v microwave applications. Specifically, the joint investigation is

designed to isolate and characterize the intermediate reaction

products which occur during synthesis. The information gained fr

these studies will improve the understanding of the chemistry >.n : structure that persist when alkoxides are mixed and how thes^ f •. - • influence the development of the precursors upon hyrolysi.3 .

83
11. University of Minnesota

Cooperative research is underway between S. Hsu and Prof. Ramalingam

on ceramic coating and coating evaluation for advanced technological

concepts.

12. University of New Hampshire

The Surface Chemistry and Bioprocesses Group is collaborating

with Prof. Richard H. Blakemore on _in vivo characterization of metal

particle formation rates and sites in magnetite-depositing bacteria,

using SANS characterization. G. J. Olson, F. E. Brinckman, and

K. Rhyne are participating in the research.

13. University of Southern California

B. Steiner and the Synchrotron Group of the Metallurgy Division have

collaborated on monochromatic topographic examination of bismuth

silicon oxide crystals during the first two weeks of dedicated x-ray

ring operation at the National Synchrotron Light Source. These

crystals display highly growth-dependent defects and strains

associated with the detailed character of the crystal growth. Such

defects can affect the performance of signal processing devices made

from such crystals. Correlation of the topographic information with

parametric variation in the crystal growth process will help to

identify those aspects of growth that most critically affect device

performance.

14. University of Tennessee Space Research Institute (UTSI)

UTSI functions are primarily of an industrial R & D nature. Their

interaction with NBS has been long standing and revolves around their

development of coal fired MHD systems and their need for NBS basic

data and models of the MHD slag behavior. UTSI provides

(E. Plante) with slag samples from their pilot plant tests, and

NBS carries out basic vaporization and phase equilibria

measurements on these samples. The results are used by UTSI and also

by J. Hastie and D. Bonnell to develop predictive models of slag

thermochemistry under actual MHD use conditions. NBS recently

completed development of a highly successful model, which is now in use by Lloyd Crawford of UTSI. This model can predict the

vaporization, seed retention, and phase equilibria behavior of

complex MHD slags containing oxides of Na, K, Ca, Mg, Al, Si, and

Fe.

15.

Virginia Polytechnic Institute and State University

Cooperative research between Prof. Larry Taylor (VPI). P. Pei, and

K. Jewett investigates surface reaction product analysis under

wearing conditions.

84
16. Washington University

G. Olson and F. Brinckman are collaborating with Prof. Simon Silver

on the molecular biology of metal resistance and transformations in

commercially applied metal ore processing bacteria.

85
STANDARD REFERENCE MATERIALS

The Division provided science, industries, and government a central source

of well-characterized materials certified for chemical composition of

physical or chemical properties. These materials are issued with a certificate and are used to calibrate instruments, to evaluate analytical

methods, or to produce scientific data which can be referred to a common

base.

SRM

DESCRIPTION NUMBER

Alumina Elasticity 718

Alumina Glass Anneal Point 714

Alumina Glass Anneal Point 715

Alumina Melting Point 742

Aluminum Magnetic Susceptibility 763-1

Aluminum Magnetic Susceptibility 763-2

Aluminum Magnetic Susceptibility 76

3

-

3 Barium Glass Anneal Point 713

Borosilicate Glass Composition 93(A)

Borosilicate Glass Thermal Expansion 731 LI Borosilicate Glass Thermal Expansion 731 L2

Borosilicate Glass Thermal Expansion 731 L.3 Cadmium Vapor Pressure 746

Container Glass Composition 621

Container Glass Leaching 622

Container Glass Leaching 623

Copper Thermal Expansion 736L1

Fused Silica Thermal Expansion 739L1

Fused Silica Thermal Expansion 739L2

Fused Silica Thermal Expansion 739L3

Glass Dielectric Constant 774

Glass Electrical Resist 624

Glass Fluorescence Source 477

Glass Liquidus Temperature 773

Glass Refractive Index 1820

Glass Sand (High Iron) 81

A

Glass Sand (Low Iron) 1 65A

Glass Stress Optical Coefficient 708

Glass Stress Optical Coefficient 709

Gold Vapor Pressure 745

High Boron Glass Viscosity 717

Intensity XRD Set 674

Lead Barium Glass Composition 89

Lead Glass Anneal Point 712

Lead Glass Viscosity 711

Liquids Refractive Index 1823

Low Boron Glass Composition 92

Lube Oil Oxidation Test Kit 1817

Lube Oxidation Catalysts 8500

86
MNF 2 Magnetic Susceptibility 766-1

Mica X-Ray Diffraction 675

Neutral Glass Anneal Point 71

6

Nickel Magnetic Susceptibility 772

Opal Glass Composition 91

Palladium Magnetic Susceptibility 765-1

Palladium Magnetic Susceptibility 765-2

Palladium Magnetic Susceptibility 765-3

Platinum Magnetic Susceptibility 764-1

Platinum Magnetic Susceptibility . 764-2

Platinum Magnetic Susceptibility 764-3

Refractive Index Glass 1822

Respirable Quartz 1878

Ruby EPR Absorption 2601

Sapphire Thermal Expansion 732

Silicon X-Ray Diffraction 640(A)

Silver Vapor Pressure 748

Soda Lime Flat Glass Composition S620

Soda Lime Float Composition 1830

Soda Lime Glass Viscosity 710

Soda Lime Sheet Composition 1 83

1

Toluene 5 ML 21 1C

Tungsten Thermal Expansion 737

87

APPENDIX

U.S.

DEPARTMENT

OF

COMMERCE

National

Bureau

of

Standards
Institute

for

Materials

Science

and

Engineering

L.

H.

Schwartz,

Director

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Li.
NBS-1 MA miv. 2-«0) u.a. DIPT, of comm. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR-85/3188

2. Performing Organ. Report No. 3. Publication Date

FEBRUARY 1986

4. TITLE AND SUBTITLE

Institute for Materials Science and Engineering - Ceramics

Technical Activities 1985

5. AUTHOR(S)

S.M. Hsu, Chief, C.R. Hubbard, Deputy

C. PERFORMING ORGANIZATION (If jafint or other than NBS. see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 29234

7. Contract/Grant No.

S. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, Stote, ZIP)

NBS - Ceramics Division, 420

Room A257/Bldg, 223

Gaithersburg, MD 20899

10.

SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-I8S. FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

Current programs of Ceramics Division are reviewed.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper nomes; and seporate key word* try jemicoionj,

ceramics; Inorganic materials; standards

13. AVAILABILITY

1 %| Unlimited

I I For Official Distribution. Do Not Release to NTIS

I 1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

Q[] Order From National Technical Information Service (NTIS), Springfield. VA_ 22161

14. NO. OF

PRINTED PAGES

97

IS. Price

$11.95

UlCOtA^OC 40«|-#|0