Process for producing silicon carbide and metal carbides

Claim 1

A process for producing substantially unagglomerated particles of a carbide of silicon or a carbide-forming metal capable of forming a gaseous sub-oxide selected from the group consisting of aluminum, boron, tantlum, titanium, zirconium, hafnium, yttrium, lanthanum, chromium, niobium, molybdenum, tungsten and vanadium from a corresponding oxide, said process comprising: forming a uniform dispersion consisting essentially of particles having an average size of less than two microns of said oxide in a polymer having the following characteristics: (a) a molecular weight of at least 10,000 and a long chain structure of at least 200 monomer units and (b) a carbon yield of at least 30% by weight. said dispersion being formed by dissolving the polymer in a solvent having a lower affinity for said oxide than the polymer, introducing the oxide particles into the resulting solution, agitating the solution to disperse the particles uniformly, and then removing the solvent from the solution such that said particles are substantially unagglomerated and separated from each other by said polymer; carbonizing the resulting dispersion in an inert atmosphere in order to convert the polymer to carbon; heating the carbonized product in an inert atmosphere in the presence of a catalyst for the formation of said sub-oxide at a first temperature, which results in the formation of carbide particles or whiskers having an average particle diameter of less than two microns, then raising the temperature to a second temperature to drive the reaction to completion; and removing any remaining excess carbon from the resulting carbide product by oxidizing the carbon.