| 摘要 |
PURPOSE:To synthesize cubic boron nitride at low pressure and temperature, by mixing specific quantities of two kinds of hexagonal boron nitride powders having different degrees of crystallinity, providing them with a synthesizing catalyst composed of cubic boron nitride, pressurizing and heating them under specific conditions. CONSTITUTION:Hexagonal boron nitride powders with a crystallinity of 1000Angstrom or more in X-ray index Lc and hexagonal boron nitride powders with a crystallinity of less than 1000Angstrom in Lc are mixed together at the ratios of 30-90 and 70-10wt.% respectively. Then, synthesizing catalyst composed of cubic boron nitride is added to said mixture, which is then pressurized and heated in a region wherein cubic boron nitride remains stable theremodynamically to synthesize cubic boron nitride(CBN). The embodiments of synthesizing catalysts for CBN are alkali metals, alkakline earth metals and nitrides thereof, wherein the mixing ratio is generally 1-30 pts.wt. catalyst per 100 pts.wt. HBN. Preferably synthesis condition is, for exanple, 1400-1700 deg.C and 40-50kb. |
