COATED HIGH PRESSURE TYPE BORON NITRIDE QUASI-FINE PARTICLE, SINTERED BODY OF THE SAME AND PRODUCTION THEREOF

摘要

PURPOSE:To produce a high performance coated high pressure type boron nitride sintered body which has uniform, dense, firmly sintered and highly controlled fine structure and is formed from coated high pressure type boron nitride quasi-fine particles. CONSTITUTION:Powdery core particles consisting of quasi-fine particles of the high pressure type boron nitride having >10mum average particle size determined by using the frequency distribution on the volume basis are dispersed in air. This dispersed powdery core particles in such a dispersed state that the dispersity beta is >=80% are allowed to come into contact with or to collide with a coating film forming material precursor to coat the surface of each of the core particles with the coating film forming material. The coated high pressure type boron nitride particles thus obtained, alone or together with a binder, are sintered under such sintering conditions of pressure and temp. that the high pressure type boron nitride is thermodynamically stable, or under the sintering conditions of pressure and temp. of <2000MPa and and <=1850 deg.C respectively. Under the latter conditions, the high pressure type boron nitride is not thermodynamically stable, however it is metastable.