Ngk Spark Plug Company, Limited

Hiromi Saguchi

Satoshi Iio

Takashi Okamura

A diamond-coated hard metal member comprising a WC-based hard metal substrate having a roughened surface formed by electrolytic etching and a diamond coat layer coating the roughened surface with an interlayer provided interposed therebetween. The interlayer coats the substrate, and is a W layer having a roughened surface corresponding to the roughened surface of the substrate. The unetched substrate comprises disperse phases dispersed therein in an amount of from 2 to 5 mol-%, and has disperse phases having an average longest diameter of from not less than 0.5 &mgr;m to less than 2 &mgr;m on the surface thereof in a density of from not less than 0.1/&mgr;m to not more than 0.2/&mgr;m .

Diamond-coated hard metal member

The present invention provides a method of manufacturing a superhard article with diamond coat having an excellent resistance against breakaway or peeling off of its coat, in particular, a cutting tool. A carbide base material formed to a desired shape containing tungsten carbide (WC) as a main component is soaked in a solution of alkali chloride and undergoes electrolytic etching on the surface of the base material at a maximum removal speed of 0.2 to 1.5 .mu.m/min for 3 to 30 minutes and, after the surface of the base material is washed, a diamond coat is developed on the surface of the base material by vapor deposition.

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Aichi, Japan

Hiromi Saguchi