Shin-Etsu Chemical Co., Ltd.

Morinobu Endou

Minoru Takamizawa

Tatsuhiko Hongu

Taishi Kobayashi

Susumu Ueno

Akira Hayashida

Hiromi Ohsaki

Nobuaki Urasato

Takasi Toide

Nichiro Suzuki

The invention provides carbon fibers coated on the surface with a layer of an amorphous silicon carbide of the composition Si.sub.x C.sub.y, x and y each being a positive number with the proviso that the ratio y/x is in the range from 0.5 to 2.5, formed by the exposure of the carbon fibers to low temperature plasma generated in an atmosphere containing an organosilicon compound having no oxygen or chlorine atom directly bonded to the silicon atom in the molecule. The carbon fibers are imparted with greatly increased resistance against air oxidation at high temperatures as well as remarkably improved affinity or wettability with plastics and molten metals along with very low reactivity with molten metals so that the carbon fibers are useful as a reinforcing material in the composite materials of carbon fiber-reinforced plastics and metals.

Carbon fibers having improved surface properties and a method for the

The invention provides a method for the preparation of an ultrafine powder of silicon carbide having an extremely fine and uniform particle size distribution of spherical agglomerate particles each formed of crystallites of 5 nm or smaller in size. The silicon carbide powder is prepared by the vapor phase pyrolysis of a specified methyl hydrogen(poly)silane as diluted with a carrier gas, e.g. hydrogen, to give a concentration of 40% by volume or lower at a temperature of 750.degree. to 1600.degree. C. The silicon carbide powder can readily be sintered at a temperature of 1750.degree. to 2500.degree. C. even without addition of a sintering aid to give a sintered body of extremely high density reaching 80% or larger of the theoretical value which can never be obtained of the conventional silicon carbide powders.

Ultrafine powder of silicon carbide, a method for the preparation

The invention provides a method for providing a highly protective coating layer of silicon carbide on to the surface of a substrate. The method comprises pyrolyzing the vapor of an organosilicon compound having at least one hydrogen atom directly bonded to the silicon atom in a molecule but having no halogen or oxygen atom directly bonded to the silicon atom at a temperature of 700.degree. to 1400.degree. C. in contact with the substrate surface to deposit silicon carbide thereon. In particular, the method is useful to form a sheath-and-core structure composed of the core of carbon filament and the coating layer of silicon carbide so that the carbon fibers are imparted with greatly improved resistance against oxidation and chemicals including molten metals when the carbon fibers are used as a reinforcing material of a fiber-reinforced metal composite as well as with improved affinity with molten resins and metals which is also an advantageous property as a reinforcing material for such matrix materials.

Method for providing a coating layer of silicon carbide on substrate

The invention provides a novel method for the preparation of silicon carbide fibers capable of being performed at a relatively low temperature and giving fibers of relatively large lengths by the vapor-phase pyrolysis of an organosilicon compound on a substrate. The method comprises contacting an organosilicon compound, which should have no halogen and oxygen atoms directly bonded to the silicon atoms and have preferably at least one hydrogen atom directly bonded to the silicon atom in a molecule, with a finely divided powder of a metal or a compound of a metal, such as copper, silver, vanadium, niobium, tantalum, iron, cobalt, nickel, palladium and platinum, at a temperature of 700.degree. to 1450.degree. C. so that the powder serves simultaneously as a catalyst and nucleus for the growth of the silicon carbide fibers thereon formed by the pyrolysis of the organosilicon compound. When the organosilicon compound is deficient of the carbon content relative to the silicon so that free silicon may be formed by the pyrolysis, admixing of a hydrocarbon to the feed of the organosilicon compound can solve the problem.

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Nagano, Japan

Morinobu Endou