Abstract: Polyorganosilanes are prepared by contact reaction of organodihalosilanes with alkali metal fine particles in an organic solvent. Prior to the contact reaction, a triorganohalosilane is contacted with the dispersion of alkali metal fine particles in organic solvent for removing reactive oxygen and moisture from the dispersion. Formation of a siloxane bond in the polysilane backbone is minimized, and polyorganosilanes having a minimal oxygen content are obtained.

Abstract: An organic silazane polymer is prepared by passing a silazane compound in por form through a hollow tube heated at 400.degree. to 700.degree. C. for activation and thermally polymerizing the silazane compound in a liquid phase. Inorganic fibers can be prepared from the organic silazane polymer by melt spinning, infusibilizing, and sintering. An apparatus for preparing an organic silazane polymer is also provided, comprising a heated reactor vessel for evaporating and thermally polymerizing a silazane compound, a heated hollow tube in flow communication with said reactor vessel for receiving the silazane compound vapor and heating it at 400.degree. to 700.degree. C. for activation, and a conduit, with a condenser for condensing the vapor, for feeding the condensed silazane compound back to the reactor.

Abstract: A process for manufacturing an organic silazane polymer which comprises: reacting ammonia with a mixture of organosilicic compounds (I) and (II) wherein R is a methyl group, an ethyl group, or a phenyl group, and R.sub.1 is a hydrogen atom or a vinyl group, and X is a chlorine or a bromine atom; then polymerizing the thus obtained silazane compound in the presence of an alkali catalyst.

Abstract: Polysilanes are produced by reacting dihalosilanes in the presence of alkali metals, By carrying out the dihalosilane reaction in the presence of copper halide catalysts at temperatures of at least 100.degree. C., higher molecular weight polysilanes are obtained in acceptable yields.

Abstract: A process of producing a methylphenyltrisiloxane having the following general formula: ##STR1## wherein R.sup.1 and R.sup.2 may be the same or different and are each a methyl or phenyl group, the process comprising the step of reacting:(A) methyldiphenylsilanol, with(B) a silazane compound having a diorganosilazane unit having the following formula: ##STR2## wherein R.sup.1 and R.sup.2 are as defined above. According to the process, colorless and odorless methylphenyltrisiloxanes can be obtained easily, safely and economically, without any special deodorizing or decoloring step.

Abstract: According to the method for preparing hexamethyl cyclotrisilazane of the present invention, hexamethyl cyclotrisilazane can be obtained by heating a linear or cyclic silazane compound represented by the following general formula:--(Me.sub.2 SiNH).sub.n --(wherein Me represents a methyl group and n is an integer of not less than 4) in the presence of at least one catalytic compound selected from the group consisting of ammonium salts of arylsulfonic acids and/or aminoarylsulfonic acids and the resulting hexamethyl cyclotrisilazane represented by the formula: --Me.sub.2 SiNH).sub.3 -- can be recovered by distilling off the same outside the reaction system. According to the method of the present invention, highly pure hexamethyl cyclotrisilazane can be industrially prepared in good efficiency and in a high yield.

Abstract: Polytitanocarbosilazane polymers useful as ceramic precursors are prepared by reacting organic silicon compounds of first and second types, a titanium compound, and a disilazane. Ceramic fibers are obtained by melt spinning the polymers followed by infusibilization and pyrolysis.

Abstract: A powdery mixture of a fine silicon carbide powder admixed with boron or a boron compound, e.g. boron carbide, titanium boride and boron oxide, as a sintering aid is compression-molded into a green body which is subjected to a sintering treatment into a sintered body. Different from conventional methods in which the sintering treatment is performed always in an atmosphere of an inert gas, e.g. argon, the sintering treatment in the inventive method is performed in an atmosphere of a rare gas containing 0.005-5% by volume of nitrogen. The sintered body of silicon carbide obtained by this method has an outstandingly high electric volume resistivity of 10.sup.10 to 10.sup.13 ohm.cm and a coefficient of thermal conductivity of 100-220 W/m.K.

Abstract: An infusible organic silazane polymer is prepared by melting, shaping, and infusibilizing an organic silazane polymer. The infusibilizing step includes two steps of treating the shaped polymer with a gas containing the vapor of an infusibilizing silicon, boron, phosphorus or metal compound and further treating with a water vapor-containing gas or ammonia gas. The infusible polymer is efficiently sintered into ceramic fibers without fusion bond.

Abstract: In place of the conventional silicon source materials used in the prior art method for the preparation of silicon carbide whiskers, the inventive method utilizes a hydrolysis product of a chlorosilane compound R.sub.a SiCl.sub.4-a or a chlorodisilane compound R.sub.b Si.sub.2 Cl.sub.6-b, in which R is a hydrogen atom or a monovalent hydrocarbon group, a is zero to 3 and b is 1 to 5, as the silicon source which is intimately mixed with a powder of carbon and the mixture is heated at 1400.degree. to 1700.degree. C. to give silicon carbide whiskers in a high conversion. Alternatively, the hydrolysis of the chloro(di)silane compound is performed in an aqueous medium in which a powder of carbon is dispersed in advance so that the hydrolysis product as formed is already a mixture with the carbon powder.

Abstract: A method for manufacturing silicon carbide whisker which has a cross-sectional diameter of greater than about 1 .mu.m by mixing a source of silicon atom in the form of grains having a mean grain diameter of at least 50 .mu.m with a carbon atom source in the presence of an element or compound of the element, the element being yttrium, calcium, manganese, aluminum, indium, or rare earth elements in an amount from about 100 to 2,000 ppm and growing the silicon carbide whisker therefrom.

Abstract: A process for preparing diorganohalogenosilanes wherein diorganodihalogenosilanes are reacted with at least one organosilicon compound having at least one .tbd.Si--H bond in the molecule and selected from polysilanes, polycarbosilanes and polysilphenylenes is described. This reaction proceeds in the presence of a Lewis acid.

Abstract: Hollow ceramic fibers are prepared by melt spinning an organic silazane polymer, infusibilizing the fiber to form an infusible layer on the surface, and pyrolyzing the fiber to obtain a ceramic fiber having an empty interior. The infusibilizing step includes two steps of treating the fiber with a gas containing the vapor of an infusibilizing silicon, boron, phosphorus or metal compound and further treating with a water vapor-containing gas or ammonia-containing gas. The surface infusible fibers are efficiently sintered into hollow ceramic fibers without fusion bond.

Abstract: A process for manufacturing an organic silazane polymer which comprises reacting ammonia with a mixture of methyldichlorosilane, methyltrichlorosilane and dimethyldichlorosilane to obtain an ammonolysis product. The ammonolysis product is polymerized in the presence of a basic catalyst capable of deprotonation to obtain an organic silazane polymer. The silazane polymer may be further melted, shaped and infusibilized. The thus infusibilized product is finally sintered to obtain a ceramic material.

Abstract: A process for manufacturing an organic silazane polymer which comprises reacting ammonia with a mixture of at least one compound selected from the group consisting of organic silicon compounds of the following formulae (I) and (II) ##STR1## and at least one compound selected from the group consisting of organic silicon compounds of the following formula (III) ##STR2## in which R represents hydrogen, chlorine, bromine, methyl radical, ethyl radical, phenyl radical or vinyl radical, R.sub.1 represents hydrogen or methyl radical, R.sub.2 represents hydrogen, methyl radical, ethyl radical, phenyl radical or vinyl radical and X represents chlorine or bromine; to obtain an ammonolysis product. The ammonolysis product is polymerized in the presence of a basic catalyst capable of deprotonation to obtain an organic silazane polymer. The silazane polymer may be further melted, shaped and infusibilized. The thus infusibilized product is finally sintered to obtain a ceramic material.

Abstract: The present invention provides a process for producing silicon carbide whiskers by reacting a starting mixture comprising starting silicon source material mainly composed of silicon and oxygen and carbonaceous material at a high temperature, wherein one or more of Fe, Co and Ni ingredients are contained in the starting mixture such that the total amount of the Fe, Co, Ni ingredients is from 25 to 2000 ppm based on the silicon ingredient in the starting silicon source material. Silicon carbide whiskers at high purity can be produced at high yield with less content of powdery silicon carbide.

Abstract: A process for manufacturing an organic silazane polymer which comprises reacting an organic silicon compound of the following formula (I): ##STR1## in which R represents hydrogen, chlorine, bromine, methyl radical, ethyl radical, phenyl radical or vinyl radical, R.sub.1 represents hydrogen or methyl radical and X represents chlorine or bromine, or a mixture of organic silicon compounds of the formula (I) above and an organic silicon compound of the following formula (II): ##STR2## in which R.sub.2 and R.sub.3 represent hydrogen, chlorine, bromine, methyl radical, ethyl radical, phenyl radical or vinyl radical and X represents chlorine or bromine with a disilazane of the following formula (III): ##STR3## in which R.sub.4, R.sub.5, R.sub.6 represents hydrogen, methyl radical, ethyl radical, phenyl radical or vinyl radical in an anhydrous state at a temperature of from 25.degree. to 350.degree. C. while distilling off by-produced organic ingredients out of the system to obtain an organic silazane polymer.

Abstract: A process for manufacturing an organic silazane polymer which comprises reacting ammonia with a mixture of methyldichlorosilane, methyltrichlorosilane and dimethyldichlorosilane to obtain an ammonolysis product. The ammonolysis product is polymerized in the presence of a basic catalyst capable of deprotonation to obtain an organic silazane polymer. The silazane polymer may be further melted, shaped and infusibilized. The thus infusibilized product is finally sintered to obtain a ceramic material.

Abstract: Sintered bodies of silicon carbide having remarkably increased volume resistivity and thermal conductivity can be obtained by heating a green body shaped of a fine silicon carbide powder admixed with boron or a boron compound, e.g. boron carbide, titanium boride and boron oxide, as a sintering aid at 1800.degree. to 2200.degree. C. in the presence of or in the vicinity of a shaped body of a powdery mixture of a fine silicon carbide powder admixed with boron nitride in the same furnace. The improvements in the volume resistivity and thermal conductivity of the sintered body are particularly remarkable when the fine silicon carbide powder is a pyrolysis product of a methyl hydrogen silane compound such as tetramethyl disilane.

Abstract: The precursor composition of silicon carbide fibers provided by the invention has greatly improved spinnability and can be spun at a very high spinning velocity to give a green filament which has a much larger tensile strength than those of conventional precursor materials and is capable of giving silicon carbide fibers having increased tensile strength by the infusibilization and calcination of the green filament of the composition under tension. The composition comprises from 80 to 99.9 parts by weight of a polycarbosilane polymer and from 20 to 0.01 part by weight of a silmethylene polymer having a degree of polymerization larger than the specified lower limit.