Investigators: Christian E. Johnson, David R. Kelley, Ed Escalante, Sandra Claggett, and Perry Sharpless

Technical Description:

These Standard Reference Materials (SRM) are intended primarily for use in calibrating Knoop and Vickers-type microhardness testers and are certified for average hardness values at 0.245 N, 0.490 N, 0.980 N, 2.94 N, 4.90 N, 9.80 N (25 g-f, 50 g-f, 100 g-f, 300 g-f, 500 g-f, 1000 g-f). This project involves the production/certification of copper and nickel standards as well as the development of a new gold standard.

Technical Objectives:

• Develop an electrodeposited gold microhardness standard having uniform hardness through the coating thickness.

• Develop a gold electrolyte from which resulting electrodeposits would have microhardness values in the range on 70 kg/mm²-90 kg/mm².

• Production of 50 SRM 1906 Nickel Microhardness Standards having uniform nominal hardness of 600 kg/mm².

• Production of 25 SRM 1894 Copper Microhardness Standards having uniform nominal hardness of 125 kg/mm².

Anticipated Outcome:

• Technical feasibility will be demonstrated for the development of an electrodeposited gold microhardness standard having uniform hardness.

• Production of 50 SRM 1906 Nickel Microhardness Standards.

• Production of 25 SRM 1894 Copper Microhardness Standards.

Accomplishments for FY1995:

• Electrodeposited pure gold (24K) was found to have non-uniform microhardness value through a thickness of 100 µm due to an increase in grain size with thickness.

• A hard gold electrolyte was modified to obtain microhardness values in a range of 70 kg/mm²-90 kg/mm² on resultant electrodeposits.

• Uniform microhardness values were obtained through the 100 µm thickness of electrodeposits obtained from the modified hard gold electrolyte due to the uniform microstructure of small equi-axed grains.

• Production of 50 SRM 1906 Nickel Microhardness Standards.

• Production of 25 SRM 1894 Copper Microhardness Standards.

Impacts and Technical Highlights:

• Feasibility was demonstrated that a (100 Êm-125 Êm) uniform gold electrodeposit could be developed as a microhardness standard.

• These SRM would satisfy a need in industry for a standard to verify microhardness testers at nominal hardness of 90 kg/mm², 125kg/mm², and 600 kg/mm².

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Last modified: Mon Jan 06 09:46:15 1997 Metallurgy Webmeister