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Institut Sverkhtverdykh Materialov Akademii Nauk Ukrainskoi Ssr

Institut Fizicheskoi Khimii Akademii Nauk

Institut Sverkhtverdykh Materialov Ssr

Alexei I Prikhna

Valentin N Bakul

Jury I Nikitin

Dmitry V Fedoseev

Boris V Deryagin

Valentin P Varnin

Valentin K Gerasimenko

Stanislav P Vnukov

Vladimir G Poltoratsky

Vladislav Sergeevich Lysanov

Leon Izrailevich Feldgun

Alexandr A Shulzhenko

Viktor V Digonsky

Nikolai V Novikov

Alexandr I Borimsky

Nekhemyan Veniaminovich Tsypin

Valerian D Yakimenko

Eduard Y Dovgal

Vyacheslav S Rovsha

Alexandr N Sokolov

Anatoly Vasilievich Hochko

Vitaly Y Egorov

Valery M Davidenko

Disclosed is a method of producing cubic boron nitride, which comprises the steps of subjecting to a pressure of from 40 to 70 kilobars and to a temperature of from 1100.degree. to 2000.degree. C. a charge including hexagonal boron nitride and a conversion initiator selected from the group consisting of alkali and alkaline earth metals and borides of the foregoing metals, doping the charge with crystallohydrate in the form of a compound selected from the group consisting of sulfur-, halogen- or nitrogen-containing salts and their mixtures incorporating at least 5 molecules of crystallization water. According to another embodiment, the aforesaid charge is doped with a member selected from the group consisting of alkali metal hydroxide or alkaline earth metal hydroxide.

Method of producing cubic boron nitride

The proposed polycrystalline superhard material comprises sintered particles of cubic boron nitride coated over the whole surface thereof with a layer of a crystalline compound of the chemical formula B.sub.x N.sub.y C.sub.z, where x, y and z can assume any value from 0 to 1, said compound binding together the particles of the cubic boron nitride. According to the present invention the proposed material is produced in the following way: particles of cubic boron nitride are placed in a flow of a gas containing carbon for a carbon layer 1-100 A thick to be built up on the whole surface of said particles. Then the particles of cubic boron nitride with the carbon layer built up over the whole surface of the particles are subjected to sintering at a temperature and under a pressure corresponding to the region of thermodynamic stability of cubic boron nitride. The herein-proposed material is highly uniform and features mechanical properties superior to those of the known cubic boron nitride materials. Thus, for example, under the identical conditions of cutting, durability of cutters made from the proposed material is 2-5 times higher than that of the cutters made from the known material based on cubic boron nitride.

Polycrystalline superhard material and method of producing thereof

A method of preparing a polycrystalline diamond member comprising sintering diamond particles having deposited thereon, not only diamond coating, but also diamond-graphite coating In the epitaxial method of coating according to the invention, diamond particles may be the finest ones of a size smaller than one micron. The resulting compact member is characterized in the absence of marked graphite inclusions, and diamond cleavage between the particles results in a considerable improvement of the strength of the compact member.

Polycrystalline diamond member and method of preparing same

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Kyiv, Ukraine

Alexei I Prikhna