| 摘要 |
PROBLEM TO BE SOLVED: To provide excellent abrasion and fracture resistances when using a cubic boron nitride sintered compact especially as a cutting tool for a ferrous material by converting a cubic boron nitride constituting the cubic boron nitride sintered compact comprising the cubic boron nitride and a continuous binder into a polycrystalline substance comprising fine crystals having an average grain diameter of a specific value or below. SOLUTION: This cubic boron nitride(cBN) sintered compact is a polycrystalline substance comprising a cubic boron nitride constituting the cubic boron nitride sintered compact and composed of fine crystals having <=1 μm average grain diameter. A compression type hexagonal baron nitride in an amount of 0.01-0.5 vol.% can be contained in the polycrystalline substance comprising the crystals of the cubic boron nitride. The polycrystalline substance comprising the crystals of the hexagonal boron nitride is obtained by using boron nitride in a low-pressure phase synthesized by reducing and nitriding a compound containing boron and oxygen in the presence of carbon and nitrogen as a starting substance, directly converting the boron nitride into the cubic boron nitride at a high temperature under a high pressure, simultaneously sintering the resultant cubic boron nitride and pulverizing the sintered compact of the single phase of the obtained cubic baron nitride. |
