ASTM RR-C28-1003 1996

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This Research Report is issued under the fixed designation RR: C28-1003. You agree not to reproduce or circulate or quote, in whole or

part, this document outside of ASTM International Committee/Society activities, or submit it to any other organization or standards

body (whether national, international or other) except with the approval of the Chairman of the Committee having jurisdiction and the

written authorization of the President of the Society. If you do not agree to these conditions, please immediately destroy all copies of

24 September 1996

Committee C28 on Advanced Ceramics

Subcommittee C28.01 on Mechanical Properties and Performance

Research Report C28-1003

Interlaboratory Study to Establish Precision Statements for ASTM

C1326, Standard Test Method for Knoop Indentation Hardness of

Advanced Ceramics

ASTM International

100 Barr Harbor Drive

West Conshohocken, PA 19428-2959

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Committee C-28 on ADVANCED CERAMICS

lJ 1

Chairman: GEORGE QUINN, NIST, Ceramics Div., Bldg. 223, Rm. A335, Gaithersburg, MD 20899 (301-975-5765)

FAX: 301-990-8729

Vice-Chairman: MICHAEL R. FOLEY, St. Gobain/Norton Industrial Ceramics Corp., Goddard Rd., Northboro, MA 01532-1545

(508-351-7900) FAX: 508-351-7723

Recording Secretary: TERRY L. RICHARDSON, AlliedSignal Aerospace Co., 46-300/302-101, P.O. Box 52181, Phoenix, AX 85072-2181

(602-231-7819) FAX: 602-231-1547

Membership Secretary: CURTIS A. JOHNSON, General Electric, Corporate R&D, P.O. Box 8, Schenectady, NY 12301 (518-387-6421)

FAX: 518-387-6204

Staff Manager: GLORIA M. COLLINS (610-832-9715)

September 16, 1996

Ms. Gloria Collins

ASTM

100 Barr Harbor Drive

West Conshohocken, PA 19428-2959

Dear Gloria,

Enclosed are three reports regarding technical work in support of C 1326-96, Standard Test

Method for Knoop Indentation Hardness of Advanced Ceramics, which was prepared by

subcommittee C 28.01, Properties and Performance. C 1326 was based on an earlier ASTM

standard: C 730, Knoop Hardness of Glass which was prepared by committee C-14, and also

ASTM standard E 384, Test Method for Microhardness of Materials, prepared by Committee

E-04. Numerous changes and technical revisions were made, however, to make C 1326-96

specific to advanced ceramics.

The enclosed reports are:

1. "Hardness Standard Reference Materials (SRM's) for Advanced Ceramics," R. Gettings,

G. Quinn, A. Ruff, and L. Ives, Verein Deutscher Ingenieure, Nr. 1194, pp 225-264,

1995.

2. "New Hardness Standard Reference Materials (SRM'S) for Advanced Ceramics," R.

Gettings, G. Quinn, A. Ruff, and L. Ives, Ceramic Engineering and Science

Proceedings, Vol. 14 #5 pp. 817-826, 1994.

3. "Development of Ceramic Hardness Reference Materials," R. Gettings, G. Quinn, A.

Ruff, and L. Ives, pp. 617-624 in New Horizons for Materials, ed. P. Vincenzini,

Proceedings of the 8th World Ceramic Congress, CIMTEC, Florence, Italy, July 1994,

Techna, Florence, 1995.

These are referred to in section 14, Precision and Bias, of C 1326 and include details from a

round robin project which was used to prepare the precision statement.

Sincerely,

George

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Chairman, C-28

encl: 3 reports as stated

- ASTM -

100 Barr Harbor Drive - West Conshohocken, PA 19428-2959 USA - Telephone: 610-832-9500 - FAX: 610-832-9666 - e-mail: service@local.astm.org

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DEVELOPMENT OF CERAMIC HARDNESS REFERENCE MATERIALS

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GETIINGS, G. D. QUINN, A. W. RUFF, and L. K. IVES

Ceramics Division, NlST, Gaithersburg, MD 20899, USA

Hardness is a frequently measured material characteristic of advanced ceramics. Measurement accuracy is often

unknown, and uncertainties of 20% are not unusual. To remedy this, two standard reference materials (SRMs)

with certified hardness values of nominally 15 GPa are under development at NlST. A cobalt-bonded tungsten

carbide was selected for the Vickers standard, and a hot isostatically-pressed silicon nitride was selected for the

Knoop hardness standard. Prototype SRMs were developed, measured, and tested for repeatability and

reproducibility of their hardness numbers, and for conformance to ASTM standards. These SRMs willfacilitate

testing procedures leading to higher accuracy and precision.

1. INTRODUCTION

Hardness is a characteristic of ceramics that is frequently measured for materials science research or materials

engineering and characterization purposes. The indentation method and load used depends upon the application.

For research purposes, Vickers, Knoop, or Berkovich indenters are used, typically with loads from 0.01 to 9.8 N.

Rockwell and Brinell indenters are rarely used for ceramics research, but are widely used for engineering

characterization. Approximately 60% of worldwide published ceramic hardness values are Vickers, with loads

usually up to about 9.8 N, 35% are Knoop, the majority of which are at 0.98 N, and 5% are Rockwell. The high

hardness of ceramics is important for cutting tool, and wear and abrasion applications.t

The difficulty in obtaining accurate and precise hardness readings is often not appreciated. Hardness is

proportional to the square of the diagonal length of the indentation, so any error in length measurement is doubled

in the hardness number. Accurate readings require a low overall uncertainty and bias in this length measurement.

There is insufficient space in this paper to detail all of the factors which contribute to the experimental uncertainty

and bias in hardness measurement; the reader is referred to several review articles for specifics.

2-10

Diamond indenter geometry, machine vibration and operator subjectivity are among the important contributing

factors. A recent Versailles Advanced Materials and Standards (VAMAS) round-robin study reported an

uncertainty of 10-15% or higher in the hardness measurement of two aluminas.

One of the four primary

conclusions of the round-robin was that there is a clear need for hardness reference materials for ceramics with

hardness greater than 10 GPa. Progress on the development of two such standard reference materials (SRMs) is

the subject of this report.

2. GENERAL

Vickers and Knoop micro- and macrohardness machines make an impression, or indentation, and enable the

operator to measure its diagonal lengths with an attached optical microscope. Most current ceramic related

hardness standards specify a 9.8 N (1 kg) indentation load, which straddles the microhardness and macrohardness

ranges.4 At lower loads there are problems arising from the load dependence of hardness4

,6,9

and measurement

uncertainty, due to the small indentation size. Cracking at the indentation is a problem at higher loads. In general,

it is desirable to make as large an indentation as possible to reduce measurement uncertainties, without causing

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ASTM RR-C28-1003 1996 是美国材料与试验协会（ASTM）发布的一项关于砖瓦及砌块材料的参考性研究报告，该文档于1996年正式归档，属于C28委员会下的技术资源。该报告为砖瓦行业提供了关键的技术数据与测试方法参考，涵盖耐火砖、隔热砖及相关砌筑材料的物理性能、耐久性指标与质量控制要求。对于建筑材料工程师、质量检测人员及产品研发者而言，该标准文档有助于确保砖瓦产品在高温环境下的稳定性与安全性，是进行产品合规性评估与行业内技术交流的重要依据。通过引用该报告，企业可优化生产工艺、提升产

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