Method of synthesizing cubic boron nitride using alkali metal fluoride

Abstract

A process for synthesizing the cubic boron nitride from the fluoride of alkali metal includes such steps as mixing hexagonal boron nitride, the mixture of LiF and Li3N and the LiH, die pressing, assembling to become block in graphite pipe, synthesizing and chemical treating to obtain red-yellow transparent cubic monocrystal.

Description

technical field [0001] The invention belongs to the field of high-temperature and high-pressure synthesis methods for superhard materials, and in particular relates to a method for selecting a new catalyst to synthesize cubic boron nitride. Background technique [0002] The hardness of cubic boron nitride (cBN) is second only to diamond, because it has a higher oxidation resistance temperature than diamond, and has excellent characteristics such as not reacting with iron group elements at high temperatures, it can be used as abrasives and made into tools, grinding wheels and Products such as honing rods have been widely used in the processing of high-hardness steel and its alloy materials. [0003] Hexagonal boron nitride is mixed with a catalyst and synthesized under high temperature and high pressure is a common method for preparing cubic boron nitride. The general cubic boron nitride synthesis method uses Li, Mg, Ca and other alkali metals and alkaline earth metals or th...

AI Technical Summary

Problems solved by technology

However, the catalyst used in this method has higher requirements on the purity and impurity content of hexagonal boron nitride, and good synthesis can only be obtained when the purity of hexagonal boron nitride is >99.8%, the content of boron oxide is <0.1%, and the graphitization index is <2. As a result, if the purity of hexagonal boron nitride is less than 98%, the content of boron oxide is greater than 0.15%, and the graphitization index is greater than 3, the particle size of cubic boron nitride obtained is less than 300 mesh, and the conversion rate is also very low.