PRODUCTION OF CUBIC BORON NITRIDE

摘要

PURPOSE:To prolong the life of an apparatus and to obtain cubic boron nitride in a high yield by adding aluminum nitride to pyrolytic boron nitride and holding them under conditions of high temp. and pressure within ranges in which cubic boron nitride is thermodynamically stable. CONSTITUTION:Aluminum nitride is added as a catalyst to pyrolytic boron nitride and they are held under conditions of high temp. and pressure within ranges in which cubic boron nitride is thermodynamically stable to convert the pyrolytic boron nitride into polycrystalline cubic boron nitride. The pyrolytic boron nitride used is highly oriented boron nitride synthesized by a special production method called a chemical vapor deposition method (CVD method). It is necessary to add the catalyst by >=0.1mol% of the amount of the pyrolytic boron nitride as starting material. In case of <0.1mol%, conversion into cubic boron nitride is not completely carried out. Even when the catalyst is added by an extremely large amount, the effect is not enhanced and the maximum effective amount is about 10mol%.