METHOD OF PRODUCTION OF BORON NITRIDE OF GRAPHITE-LIKE HEXAGONAL STRUCTURE Russian patent published in 2005 - IPC

FIELD: production of super-hard materials, l-boron in particular.

SUBSTANCE: proposed method includes preparation of first mixture at ratio of boric acid to carbamide equal to 1:1 and second mixture at ratio of these components equal to 1:3 at deviation not exceeding 10%. Additive at size of particles lesser than 300 mcm in the amount of 0.9-1.0% of mass of mixture may be introduced into first mixture. Additive contains graphite and 40-50 mass-% of boron nitride. Each mixture is heated to temperature not below 400°C at rate of heating of 120-140°C/h. Sinters of first and second mixtures are mixed at ratio of (2.9-3.1):1, respectively. As soon as the said temperature has been attained, mixture of boric acid and carbamide may be added to each sinter in the amount equal to amount of starting mixture. Sinters are mixed under conditions of premolding at grinding to size of particles lesser than 2 mm. Mixture of sinters is subjected to nitrifying at temperature of 1810-1850°C; heating is performed at rate of 50-60/min. Boron nitride thus produced has graphite-like hexagonal structure at graphitization index "g" =1.7-2.5 and purity no less than 98.0 mass-% BN.

EFFECT: enhanced operational and economical efficiency.

6 cl, 1 tbl, 13 ex