HIGH-TEMPERATURE REACTION BETWEEN SILICON-CARBIDE AND NITROGEN UNDER PRESSURE

The effects of temperature and nitrogen pressure are studied on the Si C --> Si3N4 transformation of silicon carbide powders of various phase compositions, specific surface areas, and contents of mixtures. It is shown that the degree of transformation increases with nitrogen press ure up to 10 MPa and that, in all temperature and pressure ranges of n itrogen, it is higher for bulk free powder than the preliminarily comp acted material. In 30-60 min, a complete transformation of SiC into Si 3N4 occurs under 10 MPa nitrogen pressure and at 1650-1750-degrees-C t emperature.