| 摘要 |
PURPOSE:To obtain cubic boron nitride particles at good crushing efficiencies and at high economic productivity by using a molded body of thermally decomposed boron nitride as a raw material, pressurizing and heating it to a point where conversion factor of cubic boron nitride becomes 70-95wt.% and then cooling it to a room temperature and thereafter crushing it. CONSTITUTION:As a raw material, molded bodies of thermally decomposed boron nitrides are used. The raw material is put into a high pressure cell and pressurized and heated so that the conversion factor of cubic boron nitrides becomes 70-95wt.%. After such treatment, the cell is cooled to a room temperature and then the pressure is reduced to recover the products therefrom and said products are mechanically crushed to separate boron nitride particles. Pressure, heating temperature, and period therefor are such that, in the case that ordinary molded bodies of irregular layer structure type thermally decomposed boron nitrides available on the market are used as raw material, pressure is about 6.5 GPa, while, in the case of raw material of high purity and high crystallization, pressure is about 5.9 GPa and temperature range of about 1800-2000 deg.C for 10-25 minutes is preferable. The boron nitride particles have high toughness and high grinding performance and are useful in machining ferrous metal etc. |
