APPARATUS AND METHOD FOR PRODUCING UNIFORM, FINE BORON-CONTAINING CERAMIC POWDERS

摘要

Uniform, fine ceramic powder is prepared using an apparatus comprising a cooled reactant transport member that includes an annular gas--flow space through which a sweep gas flows thereby inhibiting contact of reactants with internal reactor chamber surfaces; a reactor chamber (16); a heating means (40); and a cooling chamber (42). The reactor chamber defines a reaction zone heated by a heating means positioned to maintain an area of the reaction zone, positions adjacent to the reactant transport member at a desired temperature. The cooling chamber defines a cooling zone that communicates with the reactor chamber. The transport member temperature and the cooling chamber temperature are below that of the reactor chamber. The apparatus may be used to produce, via rapid carbothermal reduction, boron-containing ceramic powders by (1) feeding a mixture of boric oxide or a hydrate thereof and a carbon source into the reactor chamber described above through the cooled reactant transport member at a temperature below the melt temperature of the reactants; (2) reacting the reactants at a temperature above 1400.degree.C in the reaction zone to form a uniform, fine boroncontaining ceramic powder; and (3) cooling the ceramic powder product in the cooling zone. A sweep gas passing through the gas flow space minimizes contact of reactants with internal reactor surfaces.