Preparation of finely-divided refractory powders of groups III-V metal borides, carbides, nitrides, silicides and sulfides
AssigneePPG Industries, Inc.
InventorsRobert S. Sheppard, Franklin E. Groening
Life of this patent
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Abstract
The preparation of metal and metalloid carbides, borides, nitrides silicides and sulfides by reaction in the vapor phase of the corresponding vaporous metal halide, e.g., metal chloride, with a source of carbon, boron, nitrogen, silicon or sulfur respectively in a reactor is described. Reactants can be introduced into the reactor through a reactant inlet nozzle assembly. Inhibition and often substantial elimination of product growth on exposed surfaces of such assembly is accomplished by introducing the corresponding substantially anhydrous hydrogen halide, e.g., hydrogen chloride, into the principal reactant mixing zone.
Claims16
In the process of producing finely-divided refractory powder selected from the group consisting of borides, carbides, silicides, nitrides and sulfides of a metal selected from groups III-V of the Periodic Chart of the Elements by vapor phase reaction in a reactor of a halide of the selected metal and a source of boron, carbon, silicon, nitrogen or sulfur respectively as reactants, wherein the reactants are introduced into a principal reactant mixing zone of the reactor through reactant inlet assembly means and reacted to produce a finely-divided powdery product and wherein powdery product tends to accumulate and grow on exposed surfaces of the reactant inlet assembly means that are exposed to said reactants, the improvement which comprises projecting a stream of hydrogen gas into the principal reactant mixing zone, introducing said reactants and substantially anhydrous hydrogen halide into the principal reactant mixing zone, said hydrogen halide being introduced in amounts sufficient to retard growth of powdery product on said exposed surfaces, the halide portion of said hydrogen halide corresponding to the halide of the selected metal, reacting said reactants out of contact with exposed surfaces of the reactor, and removing the powdery product from the
In the process of producing finely-divided refractory powder selected from the group consisting of borides, carbides and nitrides of a metal selected from groups III-V of the Periodic Chart of the Elements by vapor phase reaction in a reactor of a halide of the selected metal and a source of boron, carbon or nitrogen respectively as reactants, wherein the reactants are introduced into a principal reactant mixing zone of the reactor through a reactant inlet assembly means and reacted to produce a finely-divided powdery product and wherein powdery product tends to accumulate and grow on exposed surfaces of the reactant inlet assembly means that are exposed to said reactants, the improvement which comprises projecting a hydrogen plasma stream into the principal reactant mixing zone, introducing said reactants and from about 2 to about 80 weight percent, based on the selected metal halide, of substantially anhydrous hydrogen halide into the principal reactant mixing zone, said amount of hydrogen halide being sufficient to retard growth of powdery product on said exposed surfaces, the halide portion of said hydrogen halide corresponding to the halide of the selected metal, reacting said reactants out of contact with exposed surfaces of the reactor, and removing the
Dependencies are inferred from the claim text.