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Ivan Fedorovich Vovchanovsky

Valentin N Bakul

Nekhemian Veniaminovich Tsypin

Igor Ivanovich Bilyk

Dolores Khaimovna Bronshtein

The method of preparing superhard articles consists of placing a mixture of powdered hard-alloy matrix material and diamond grains into a hard-alloy envelope formed from a hard-alloy material, preferably of exactly the same composition as the hard-alloy matrix material of the mixture, with the thickness of the hard-alloy envelope over the entire area thereof exceeding by at least 3-4 times the maximum space between any two adjacent diamond grains within the mixture. The mixture in the envelope is then subjected to sintering in a free condition thereof, without any external mechanical loads being applied thereto.

Method of making superhard articles

A superhard article is produced by heating in two steps a mixture of a hard-alloy matrix material and diamond grains less than 1 mm in size in a graphite press mould. During the first heating step, the mixture is heated to a temperature of 1,200.degree. C at a rate of 1,000.degree.-1,100.degree. C per minute by heating the press mould by high frequency. During the second heating step, the mixture is heated to the sintering temperature, up to 1,800.degree. C at a rate of 3,000.degree.-10,000.degree. C per minute by heating the mixture by the resistance method, i.e. by passing electric current through the mixture while simultaneously heating the press mould by high frequency currents.

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Kyiv, Ukraine

Ivan Fedorovich Vovchanovsky