Method is developed for sintering diamond powder which uses metallic cobalt as binder. Present samples show maximum microhardness of over 3000 kg/sq mm on Knoop scale. Material may be used as hard surface coating or may compete with cubic boron nitride as abrasive grain

Katzman, H.

Libby, W. F.

English

NASA Technical Reports Server

August 1972	 B72-10519 
NASA TECH BRIEF 
NASA Headquarters 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Sintered Diamond Compact 
The problem: 
Tungsten carbide or carbonado is one of the recent 
products of diamond compact synthesis. Although this 
material is hard (1700 kg/mm2 ), it is not simple to 
produce. 
The solution: 
A method has been developed for sintering diamond 
powder which uses metallic cobalt as a binder. Present 
samples show maximum microhardness of over 3000 
kg/mm2 on the Knoop scale. 
The samples are heated by means of an internal 
graphite heater to 1590°C with the pressure maintained 
by a piston cylinder at 62x108
 N/m 2 (900,000 psi). This 
condition is maintained for about 20 minutes after 
which the samples are cooled to room temperature for 
about one hour. During the cooling, pressure is slowly 
released to minimize the residual strains in the samples. 
The best samples obtained show microhardness of 
3000 kg/mm2
 on the Knoop scale and contain 20%
Using Metallic Cobalt Binders 
cobalt by volume and diamond particle sizes of 0 to 3 
pm. This material may be used as a hard surface coating 
or may compete with cubic boron nitride as an abrasive 
grain. 
Note: 
1. Further studies are being conducted to determine if 
the material could be produced in large sections. In 
addition, other binder combinations are considered 
instead of cobalt to possibly reduce the temperature 
and pressure conditions needed for formulation. 
Technology Utilization Officer 
NASA Headquarters 
Code KT 
Washington, D.C. 20546 
Reference: TSP72-105 19 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
[42 U.S.C. 2457(f)], to the University of California, 
Los Angeles, California 90024. 
Source: W. F. Libby and H. Katzman of 
University of California 
under contract to
NASA Headquarters
(HQN- 10706) 
40 How it's done: The starting materials are diamond powder of either 
0-3 pm or 10-20 pm size and cobalt powder of 0-5 pm 
size and 99.9+% purity. These powders are dried, 
weighed, and mixed, and then packed into tantalum 
containers for sintering.
Category 04 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000518 2020-03-17T03:34:03+00:00Z


Sintered diamond compacts using metallic cobalt binders

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