SETT ATT FRAMSTELLA POLYKRISTALLIN BORNITRID

摘要

1459758 Polycrystalline boron nitride INST PROBLEM MATERIALOVEDENIA AKAD NAUK UKRAIN SSR and POLTAV ZAVOD ISKUSSTVENNYKH ALMAZOV I ALMAZ INSTRUMENTA 18 Dec 1973 [18 Dec 1972] 58597/73 Heading C1A Polycrystalline boron nitride is produced by compressing and heating a starting mixture obtained by shock-wave treatment of graphitelike BN and consisting of highly defective wurtzite-like BN and from 1 to 50 wt. per cent of graphite-like BN, at pressure and temperature values corresponding to the region of the phase diagram which is situated to the left of the graphite-like BN/compact BN equilibrium line and the cubic BN/wurtzite-like BN equilibrium line. The mixture may be compressed at 50- 300 kbars and heated to 20-3000‹ C. and prevented from contacting the pressure transmitting medium. The product may be polycrystalline BN having the wurtzite structure and may be used for making super-hard machine tools.