The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 28, 1989
Filed:
Jul. 29, 1987
Geoffrey J Davies, Randburg, Transvaal, ZA;
Lesley K Hedges, Brackenhurst, Transvaal, ZA;
Stuart H Robertson, Johannesburg, Transvaal, ZA;
Other;
Abstract
A method is provided for producing large cubic boron nitride crystals having the size of 0.1 carat or larger. The method involves providing a reaction vessel which contains CBN seed material (32), a CBN source (26) separated from the seed material and sandwiched between two masses (22) (24) of solvent/catalyst for CBN synthesis which is capable of melting under CBN synthetic conditions, and contains sufficient hexagonal boron nitride to saturate the catalyst with boron nitride when molten, the separation of seed material and source material being such that under the operating conditions of CBN synthesis a temperature gradient is created between the seed material and the source material with the seed material being located at a point near the minimum value of temperature of the temperature gradient and the source material being located at a point near the maximum value of temperature of the temperature gradient, placing that reaction vessel in the reaction zone of a high temperature/high pressure apparatus and subjecting the contents of the reaction vessel to conditions of temperature and pressure in the CBN stable region of the boron nitride phase diagram for a period of at least several hours and not more than 24 hours.