Preparation of finely-divided refractory powders of groups III-V metal borides, carbides, nitrides, silicides and sulfides

Claim 2

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

Claim 3

The process of claim 1 wherein the amount of hydrogen halide used is from about 1 to about 100 weight percent based on the selected metal

Claim 4

The process of claim 2 wherein the metal halide is the metal chloride

Claim 5

The process of claim 3 wherein the selected metal is silicon, titanium,

Claim 6

The process of claim 1 wherein the refractory powder is selected from the borides, carbides and nitrides of the metals of groups IV and V of the

Claim 7

The process of claim 5 wherein the refractory powder is selected from the borides, carbides and nitrides of a metal selected from the group consisting of silicon, titanium and zirconium, the amount of hydrogen halide used is from about 2 to about 80 weight percent based on the selected metal halide, the metal halide is the metal chloride and the

Claim 8

The process of claim 1 wherein the stream of hydrogen gas is a hydrogen

Claim 9

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

Claim 10

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

Claim 11

The process of claim 8 wherein the refractory powder is selected from the borides, carbides and nitrides of the metals of groups IV and V of the

Claim 12

The process of claim 8 wherein the hydrogen halide is used in amounts

Claim 13

The process of claim 8 wherein the metal halide is the metal chloride.

Claim 14

The process of claim 8 wherein the refractory powder is selected from the borides, carbides and nitrides of silicon, titanium or zirconium, the metal halide is the metal chloride, and the hydrogen halide is hydrogen

Claim 15

The process of claim 12 wherein the boride is titanium diboride and the

Claim 16

The process of claim 13 wherein the reactants are introduced into the reactor at temperatures below the temperatures at which the reaction is conducted and the reactants are heated to such reaction temperatures with

Claim 17

The process of claim 14 wherein the refractory powder is titanium diboride, the reactants are titanium tetrachloride and boron trichloride,

Claim 18

The process of claim 14 wherein the refractory carbide is titanium carbide or silicon carbide, the metal halide is titanium tetrachloride or silicon tetrachloride respectively, the source of carbon is hydrocarbons, halogenated hydrogens or mixtures of such compounds containing from 1 to 12 carbon atoms, and the hydrogen halide is hydrogen chloride.