Importance

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Abstract

A high-strength, coated cemented carbide product comprising a cemented carbide substrate and a fully dense alpha aluminum oxide coating on the substrate. The coating has a thickness of from 1-20 microns and is firmly and adherently bonded to the cemented carbide substrate through a thin intermediate nonmetallic layer .[.of an iron group metal aluminate.].. The coated product combines a wear resistance substantially as high as aluminum oxide cutting materials and a transverse rupture strength of at least 150,000 p.s.i. The coated product is prepared by passing water vapor, hydrogen gas and an aluminum halide over the substrate at a temperature of from 900.degree.-1250.degree. C., the ratio of water vapor to hydrogen gas being between about 0.025 and 2.0.

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First Claim