| 摘要 |
1481026 Boron nitride particles GENERAL ELECTRIC CO 29 July 1974 [6 Sept 1973] 33346/74 Heading ClA Soft hexagonal boron nitride particles of larger than 50Á average particle size are produced by a method which comprises: (a) mixing soft hexagonal boron nitride particles of less than 50 Á average particle size with a metallic nitride selected from the group consisting of alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead and antimony, and mixtures thereof, preferably lithium nitride, the boron nitride comprising 50-85 mole per cent of the boron nitride-metallic nitride mixture; (b) heating the mixture to a temperature of 1100‹ C to 1550‹ C for a period of at least twenty minutes; (c) cooling the mixture; and (d) separating the enlarged boron nitride particles from the mixture. The separation is preferably carried out by dissolving the by-products in water. The particle size of the product is normally larger than 100 Á. The process may be carried out at high pressures, e.g. 40 kilobars. |
