Kureha Kagaku Kogyo Kabushiki Kaisha

Kureha Chemical Industry Company, Limited

Ryuichi Kurita

Tatsuhiko Noguchi

Saburo Hori

Kiichi Endo

Ken Nemoto

Sigeru Seki

Minoru Ohta

A mullite-alumina composite sintered body composed of from 75 wt % to 85 wt % Al.sub.2 O.sub.3 balance SiO.sub.2, consisting of two crystalline phases, mullite and .alpha.-phase alumina, and being free from glass phase, wherein both of the average diameters of mullite grains and .alpha.-phase alumina grains are not more than 1.0 .mu.m, the content of grains having the longitudinal-length of not less than 2.5 .mu.m is 1% or less in the observation of a cross section of said sintered body, and the porosity of said sintered body is 1% or less. The sintered body of the present invention is produced by a process comprising the steps of preparing a starting powdery material composed of from 75 wt % to 85 wt % Al.sub.2 O.sub.3 balance SiO.sub.2 and containing amorphous phase from 65 wt % to 90 wt %, wherein each particle of said starting powdery material contains both Al.sub.2 O.sub.3 and SiO.sub.2, and sintering said starting powdery material at a temperature in the range from 1500.degree. C. to 1650.degree. C. The sintered body of the present invention has a high bending strength exceeding 500 MPa at room temperature.

Mullite-alumina composite sintered body and process for producing the

Alumina-zirconia ceramic powders comprise from 10% to 25% by weight of zirconium oxide having specific crystalline phases and from 75% to 90% by weight of aluminum oxide having specific crystalline phases, and have an average particle size of no more than 1,000 .ANG.ngstroms and a two-phase structure wherein the zirconium oxide phase is dispersed in the aluminum oxide phase. A method of making such alumina-zirconia ceramic powders comprises the steps of suspending composite powders having a specific chemical composition and a specific average particle size in water to form a slurry, freeze-drying the slurry, and calcining the freeze-dried powder at atmospheric pressure in air at a temperature of from 800.degree. C. to 1,250.degree. C.

Alumina-zirconia ceramic powders and a method of making the same

There is provided a novel detergent composition containing no phosphorus component, which comprises an anionic and/or nonionic synthetic surfactant(s) and an effective amount of a mixture in a specified proportion consisting essentially of an imido-bis-sulfate salt, a palmitate salt and an N,N-bis(carboxymethyl)glutamate salt and/or a salt of N,N-bis(carboxymethyl)phenylalanine. The detergent composition exhibits the detergency at least equivalent to conventional detergent compositions containing 20% or more of sodium tripolyphosphate and causes no pollution problems.

Phosphate-free detergent composition

A detergent composition containing an anionic surface active agent and/or a nonionic surface active agent, characterized by containing as a builder 5 to 50% by weight of a salt of imido-bis-sulfuric acid, 0.05 to 30% by weight of a salt of a saturated or unsaturated fatty acid or a mixture thereof and 0.1 to 15% by weight of a salt of a polycarboxylic acid or a mixture thereof.

Detergent composition

A self-hardening composition for making sand molds comprising a molding sand, a water glass as a binder and at least one salt of imidodisulfonic acid as a hardener.

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Iwaki, Japan

Ryuichi Kurita