Abstract: A composition and method for producing boron carbide/titanium diboride composite ceramic powders is disclosed. The process comprises the ordered steps of (a) intimately mixing as reactants boron carbide and a titanium source, such that the average reactant particle size is less than about 20 microns and substantially all discrete reactant areas are less than about 50 microns, and (b) reacting the product of step (a) under conditions sufficient to produce a boron carbide/titanium diboride composite ceramic powder wherein at least a portion of the boron carbide particles form substrates to which at least a portion of the titanium diboride particles are attached. The method can be used to produce a composite ceramic powder having boron carbide and titanium diboride particles less than about 20 microns in diameter.

Abstract: A process for preparing silicon carbide by carbothermal reduction is disclosed. This process involves rapidly heating a particulate reactive mixture of a silica source and a carbon source to form a product which shows improved uniformity of crystal size. The product of this process can be used to form a densified part.

Abstract: Uniform, fine ceramic powder is prepared using an apparatus comprising (a) a cooled reactant transport member; (b) a reactor chamber; (c) a heating means; and (d) a cooling chamber. The reactant transport member comprises a wall defining a conduit that communicates with the reactor chamber, with a gas-flow space being defined along the perimeter of the transport member and in communication with the reactor chamber. The reactor chamber comprises a wall defining a reaction zone, and the heating means is associated with the reaction zone, and adapted for heating reactants in the reaction zone. The cooling chamber comprises a wall defining a cooling zone that communicates with the reactor chamber. In one embodiment the communication is by means of a cooling inlet, the diameter of the cooling zone being larger than the diameter of the cooling inlet. The temperatures of the reactant transport member, the reactor chamber, and the cooling chamber are independently controllable.

Abstract: Uniform, fine ceramic powder is prepared using an apparatus comprising (a) a cooled reactant transport member; (b) a reactor chamber; (c) a heating element; and (d) a cooling chamber. The reactant transport member comprises a wall defining a conduit that communicates with the reactor chamber, with a gas-flow space being defined along the perimeter of the transport member and in communication with the reactor chamber. The reactor chamber comprises a wall defining a reaction zone, and the heating element is associated with the reaction zone, and adapted for heating reactants in the reaction zone. The cooling chamber has a wall defining a cooling zone that communicates with the reactor chamber. In one embodiment, the communication is through a cooling inlet, the diameter of the cooling zone being larger than the diameter of the cooling inlet. The temperatures of the reactant transport member, the reactor chamber, and the cooling chamber are independently controllable.