Abstract: 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.

Abstract: Silicon nitride powder having a uniform particle size of regular crystals is produced by a process comprising the steps of:(1) reacting (i) at least one compound having the general formula [I]R.sub.m SiCl.sub.4-m [I]wherein R is an aliphatic residual group having 1 to 4 carbon atoms or an aromatic residual group having 6 to 8 carbon atoms and m is 1, 2, or 3 and (ii) a compound having the general formula [II]H.sub.n SiCl.sub.4-n [II]wherein n is 0, 1, 2, or 3, the ratio of silicon atoms to carbon atoms (Si/C) in both compounds [I] and [II] being 0.5 to 50 with ammonia and, then,(2) calcining the resultant reaction product in the first step at a temperature of 1200.degree. C. to 1700.degree. C. under an inert or reducing gas atmosphere.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Trioxane can advantageously be polymerized in the presence of a thiocyanate (an ester of thiocyanic acid), to obtain an oxymethylene polymer having thermal stability. The polymerization is further promoted by means of an ionizing radiation or an ultraviolet light.

Abstract: 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.