Japan Atomic Energy Research Institute

Japan Atomic Energy Agency

Masaki Sugimoto

Kiyohito Okamura

Masahito Yoshikawa

Akira Idesaki

Seiichi Tagawa

Tadao Seguchi

Noboru Kasai

Yosuke Morita

Katsuyoshi Takano

Shuhei Seki

Aichi Inouye

Shunya Yamamoto

Satoshi Tsukuda

Masayoshi Itoh

Tsuyoshi Mitsuhashi

A hydrogen gas detecting material, which changes in light absorption characteristics when exposed to an atmosphere containing hydrogen, and the coating method are characterized in that (1) the principal component of the hydrogen gas detecting material is tungsten oxide, (2) palladium is deposited on the surface of the tungsten oxide, (3) the tungsten oxide is coated on a substrate by a sputtering method involving a controlled oxygen pressure, and (4) the temperature of the substrate during coating with the tungsten oxide is room temperature (20&#xb0; C.).

Hydrogen gas detecting material and the coating method

An improved process for producing a silicon carbide ceramic micro tubes (SiC micro tube) from a silicon-based polymer fiber by applying an ionizing radiation such that the surface part of the fiber selectively undergoes oxidative crosslinking, extracting the uncrosslinked core part of the fiber with an organic solvent to form a hollow fiber, and firing it in an inert gas is characterized by using a polymer blend of polycarbosilane and polyvinylsilane as the silicon polymer or applying the ionizing radiation to the silicon-based polymer fiber as it is cooled. The two methods may be performed either individually or in combination to produce tubes with their wall thickness controlled at a desired value in the range of 2-10 &#x3bc;m although this has been impossible to achieve in the prior art.

Process for producing silicon carbide ceramic micro tube with thin wall

A method by which ceramic nanowires with diameters ranging from several to several tens of nanometers can be synthesized with improvements in the shape retention of the nanowires and the yield of conversion to ceramic, which method comprises the steps of forming a thin film of a silicon-containing polymer usable as a ceramic precursor, irradiating the thin film with ion beams to form cylindrical crosslinked portions, extracting the un-crosslinked portions with a solvent to produce nanowires of the silicon-containing polymer, irradiating the nanowires with an ionizing radiation so that they are crosslinked again, and firing the re-crosslinked nanowires.

Ceramic nanowires and a process for producing them by ion beam irradiation

A process for producing a SiC ceramic microtube by oxidizing the surface of an organosilicon polymer to become infusible by exposure to an ionizing radiation, extracting the uncrosslinked central portion of the fiber with an organic solvent to make a hollow silicon polymer fiber, and firing it in an inert gas so that it acquires a ceramic nature.

Process for producing microceramic tubes by radiation exposure of silicon-based polymers

Polycarbosilane is mixed with 5-35 wt % of polyvinylsilane to prepare a silicon-base polymer blend which is impregnated in silicon carbide fibers or fabrics to form a preceramic molding body which is exposed to an ionizing radiation to be rendered curing and then fired in an inert gas to produce a composite in which the silicon carbide matrix is reinforced with the silicon carbide fibers.

Process for producing silicon carbide composites from silicon-based polymers by radiation application

Ultra-high-strength refractory silicon carbide fiber having a decomposition temperature of not less than about 1800K, a breaking strength of not less than about 5 GPa, and a modulus of elasticity of not less than about 300 GPa is disclosed, which is obtained by irradiating a precursor comprising organosilicon compound fiber with an ionizing radiation in a mixed carrier gas comprising a reactive gas and a first inert gas to render the precursor infusible and calcining the irradiated precursor in a second inert gas. Irradiation damage can be minimized, and no oxygen is incorporated into the fiber.

Growing community of inventors

Takasaki, Japan

Masaki Sugimoto