Silicon nitride powders for ceramics obtained by carbothermal reduction, and process for their manufacture

摘要

Silicon nitride Si3N4 powders by a silica carbothermal reduction and nitriding route, capable of being employed especially for the manufacture of ceramics and exhibiting a specific surface of at least 30 m2/g. Process for the manufacture of the powders comprising the following stages: a) From silica, from a binder generating carbon not later than during the carbothermal reduction reaction and, if appropriate, from additional carbon, manufacture of granules with a controlled pore volume. b) Carbothermal reduction reaction of the granules obtained under a, in the presence of an atmosphere containing nitrogen. c) Decarburisation. d) Obtaining powders. h