Process for preparing an amorphous, extra-hard material based on boron nitride

摘要

PCT No. PCT/EP93/00314 Sec. 371 Date Jul. 29, 1994 Sec. 102(e) Date Jul. 29, 1994 PCT Filed Feb. 9, 1993 PCT Pub. No. WO93/16015 PCT Pub. Date Aug. 19, 1993A process for preparing amorphous ultrahard material based on boron nitride which has a hardness sufficient to scratch diamond uses hexagonal or turbostratic boron nitride hBN as starting material. The starting material is compressed at pressures of at least 70 Kbar and heated to temperatures of at least of 1650 DEG C. until a boron nitride melt is obtained, the boron nitride melt is quenched by shutting off the heat supply and the quenched boron nitride melt is then relieved of the pressure. In the process, the hexagonal or turbostratic boron nitride employed as a starting material is treated in the presence of crystallisation inhibitors so that the formation of crystals is completely prevented and an amorphous structure is compacted by incorporation of reaction products comprising boron suboxides.