Ube Industries, Inc.

Toshihiko Hogami

Kyoji Ohdan

Kenji Matsunaga

Shinji Kajii

Sumio Umemura

Fumihiko Sakai

Kenichi Suzuki

Masataka Fuginaga

Masataka Fujinaga

Mitsuhiko Sato

Toshihiro Ishikawa

Yasuo Bando

An SiC fiber bonded ceramic constituted of both a base material which comprises both inorganic fibers made mainly of a sintered SiC structure containing 0.01 to 1 wt % of oxygen (O) and at least one of Groups 2A, 3A and 3B metals and a 1 to 100-nm and carbon (C)-base boundary layer formed among the fibers and a surface part which is made mainly of an SiC-base ceramic structure and formed on at least part of the surface of the base material, characterized in that the boundary portion between the surface part and the base material takes such a gradient structure that the structure of the base material changes into the structure of the surface part gradually and continuously.

SiC fiber-bonded ceramic and process for production of the same

Production processes of an inorganic fiber-bonded ceramic component comprising inorganic fibers mainly comprising Si, M, C and O, an inorganic substance mainly comprising Si and O and boundary layers comprising carbon as a main component; and an inorganic fiber-bonded ceramic component comprising inorganic fibers which are composed mainly of a sintered structure of SiC and contain specific metal atoms and boundary layers composed mainly of carbon, wherein a preliminary shaped material is set in a carbon die, covered with a carbon powder and then hot-pressed to load a pseudo-isotropic pressure on the preliminary shaped material; and a highly heat-resistant inorganic fiber-bonded ceramic component almost free from the occurrence of peelings of surface fibers or delamination, wherein fibers are aligned in a surface shape.

Highly heat-resistant inorganic fiber-bonded ceramic component and process for the production thereof

A highly heat-resistant sintered SiC fiber bonded material free of a decrease in strength and less breakable at an ultra-high temperature over 1,400.degree. C., comprising inorganic fibers which are composed mainly of a sintered SiC crystal, contain at least one kind of metal atoms selected from the class consisting of metal atoms of the 2A, 3A and 3B groups of the periodic table and are bonded nearly in the close-packed structure and 1 to 50 nm boundary layers composed mainly of carbon which are present at the interface of fibers, the less breakable highly heat-resistant sintered SiC fiber-bonded material having a density of at least 2.7 g/cm.sup.3 and an elastic modulus of at least 200 GPa, and a process for the production thereof.

Sintered SIC fibers bonded material

A heteropolyacid type catalyst capable of producing methacrylic acid from methacrolein and molecular oxygen at an extremely high yield for a long time at a relatively low temperature for a short contacting time under a vapor phase is provided. This catalyst is prepared by:

Methacrylic acid production catalyst

An improved catalyst suitable for use in the production of an unsaturated carboxylic acid by the catalytic vapor phase oxidation of an unsaturated aldehyde is provided. In this catalyst, a heat-resistant inorganic substance, such as alumina, silica-alumina and silicon carbide, having a particle diameter of 3 through 10 mm, an apparent porosity of 35 through 60%, a water absorption of 20 through 50%, an average pore diameter of not less than 40 microns, a specific surface area of not more than 2 m.sup.2 /g and a bulk specific gravity of 1.5 through 2.0 is used for supporting a composition containing molybdenum, phosphorus, vanadium and the alkali metals. The use of the above-mentioned carrier results in the advantages that the unsaturated carboxylic acid, such as methacrylic acid, can be selectively produced from the unsaturated aldehyde at a high yield and that the mechanical strength of the catalyst is remarkably improved.

Catalyst for production of unsaturated carboxylic acid, preparation

Methacrolein is catalytically oxidized into methacrylic acid in the vapor phase at a temperature of 200.degree. to 450.degree. C. The catalyst used is comprised of molybdenum, phosphorus, potassium and/or cesium, vanadium, silver and/or tellurium, and oxygen, and represented by the formula:

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Ube, Japan

Toshihiko Hogami