Ube Industries, Inc.

Tadashi Iwai

Takashi Kawahito

Masahiro Tokuse

Tetsuo Yamada

Hisayuki Mizuno

Masao Miura

Silicon tetrachloride is effectively and efficiently produced at a relatively low temperature and at a high yield by (1) feeding a mixture of a silicon dioxide containing substance and carbon to the top of a reactor in which a reaction mixture forms a downwardly flowing moving bed, (2) feeding gaseous boron trichloride to an intermediate portion of the reactor, (3) feeding gaseous chlorine to a portion of the reactor located below the boron trichloride feed portion, and (4) feeding an inert gas to a portion of the reactor located below the chlorine feed portion, whereby a silicon tetrachloride formation reaction is carried out in the moving bed and the formed silicon tetrachloride is recovered from a gas mixture discharged from the top of the reactor.

Production process of silicon tetrachloride

Silicon nitride powder having a uniform particle size of regular crystals is produced by a process comprising the steps of:

Process for producing silicon nitride powder

A method of preparing polycarbosilanes having high molecular weight and also having the major structural unit of silicon-carbon linkage. The method comprises heating a polysilane at 50.degree.-600.degree. C. in atmosphere of an inert gas and distilling out a low molecular weight polycarbosilane fraction having the number mean molecular weight of 300-600, followed by polymerizing the fraction by heating it at 250.degree.-500.degree. C. in atmosphere of an inert gas. The polycarbosilane obtained by the method of the present invention is useful for the precursor of preparing silicon carbide fibres and shaped articles.

Method of preparing polycarbosilanes

The carbonitrides of metals of Groups IV, V and VI of the Periodic Table are prepared by calcining a precursor obtained by (i) reacting the reaction product of ammonia and the halide of a metal selected from the group consisting of Groups IV, V and VI of the Periodic Table of Elements with polyphenol, or (ii) reacting the reaction product of polyphenol and the halide of a metal selected from the group consisting of Groups IV, V and VI of the Periodic Table of Elements with ammonia, the amount of the polyphenol being within the range defined by the following relationship: ##EQU1## wherein a is the number of hydroxyl groups contained in one molecule of the polyphenol, b is the number of moles of the polyphenol and c is the number of moles of the metallic halide. The desired metallic carbonitride in the form of finely divided powder having a uniform size and excellent sintering properties can be obtained at low energy consumption.

Process for producing carbonitride of metal

The carbonitrides of metals such as those of Groups IV, V and VI of the Periodic Table are prepared by calcining a precursor obtained by (i) reacting the reaction product of ammonia and the halide of a metal with carbohydrate and/or polyvinyl alcohol, or (ii) reacting the reaction product of carbohydrate and/or polyvinyl alcohol and the halide of a metal with ammonia. The desired metallic carbonitride in the form of finely divided powder having a uniform size and excellent sintering properties can be obtained at low energy consumption.

Process for producing metallic carbonitride

The chlorides of elements of Groups III, IV and V of the Periodic Table, such as, boron trichloride, silicon tetrachloride, zirconium tetrachloride and vanadium tetrachloride are prepared by heating activated carbon particles having a supported aqueous solution of compounds of the elements of Groups III, IV and V of the Periodic Table thereon at a temperature of from 300.degree. through 1000.degree. C. and, then, reacting the resultant activated carbon particles with chlorine.

Process for producing chloride of elements of Group III, IV or V of

Fine metallic nitride powders having a high purity are prepared, without causing any plugging or other problems in the reaction apparatus and with easy heat control of the reaction, by reacting a metallic halide with liquid ammonia in the presence of an organic solvent which has a specific gravity higher than that of liquid ammonia, and also is not miscible or is only slightly miscible with liquid ammonia at a reaction temperature. The process according to the present invention is effected by introducing the metallic halide into the lower organic solvent layer of the reaction system.

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Ube, Japan

Tadashi Iwai