Smith International, Inc.

Matthew W Collier

Xian Yao

Madapusi K Keshavan

Ghanshyam Rai

Brian G Bowers

The polycrystalline cubic baron nitride cutting tool has a particle size in the range of from 10-17 microns. In addition to CBN, the tool has from 2%-15% by weight of a refractory compound selected from the group consisting of titanium carbonitride, titanium aluminum carbonitride, titanium carbide, titanium nitride, titanium diboride and aluminum diboride. When using one of the carbonitrides, the carbon to nitrogen proportion is preferably in the range of from 30 atomic percent carbon and 70 atomic percent carbon to 70 atomic percent carbon and 30 atomic percent nitrogen, and preferably is about 50/50. In addition, there is an infiltrate containing aluminum and/or silicon. A quantity of diamond crystals more than stoichiometric with the amount of silicon infiltrated is included in the composition for forming silicon carbide. The cutting tool is not formed on a cemented tungsten carbide substrate so is substantially free of cobalt.

Polycrystalline cubic boron nitride cutting tool

The polycrystalline cubic boron nitride cutting tool has a particle size in the range of from 10-17 microns. In addition to CBN, the tool has from 2%-15% by weight of a refractory compound selected from the group consisting of titanium carbonitride, titanium aluminum carbonitride, titanium carbide, titanium nitride, titanium diboride and aluminum diboride. When using one of the carbonitrides, the carbon to nitrogen proportion is preferably in the range of from 30 atomic percent carbon and 70 atomic percent nitrogen to 70 atomic percent carbon and 30 atomic percent nitrogen, and preferably is about 50 atomic percent carbon and 50 atomic percent nitrogen. In addition, there is an infiltrant containing aluminum and/or silicon. The cutting tool is not formed on a cemented tungsten carbide substrate so is substantially free of cobalt.

A polycrystalline cubic boron nitride cutting tool is from 50 to 85% by weight cubic boron nitride crystals bonded together as a polycrystalline mass. A supporting phase commingled with the polycrystalline cubic boron nitride is made from 15 to 40% by weight of a refractory material which is preferably titanium carbonitride or titanium aluminum carbonitride. The starting composition also comprises from 4 to 10% by weight of Co.sub.2 Al.sub.9. Mixed powders of these ingredients are treated in ammonia at a temperature in the range of from 1000.degree. to 1250.degree. C., which significantly increases the nitrogen content and reduces carbon content of titanium carbonitride. Instead of mixed powders of the starting materials, coated particles may be used such as cubic boron nitride coated with titanium carbonitride, or titanium carbonitride coated with cobalt, aluminum or cobalt aluminide. Hexagonal boron nitride may be substituted as a starting material for a portion of the cubic boron nitride.

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Draper, UT, United States of America

Matthew W Collier