Synthesis of polycrystalline cubic BN

Abstract Polycrystalline cubic BN is obtained in a form of lump bodies, by direct conversion from hexagonal BN at pressures of about 60 kbar. Density of this material is very close to the theoretical value. Its hardness, compressive strength and chemical inertness at high temperature suggest that it is a promising material for cutting tools. Similar lump bodies are obtained also by sintering cubic BN powder. In this case, pressures to be applied in sintering can be much lower than those required for the conversion of hexagonal to cubic BN. These processes are successfully applied to cement powder of diamond into a compacted body.