Nissan Chemical Industries Limited

Takao Kaga

Yutaka Kimura

Isao Ota

Tohru Nishimura

Toshio Kasai

Kenji Tanimoto

Masamichi Obitsu

Yuzi Hoshi

Hiroaki Tanaka

Isao Tomi

Yasuhiro Fujii

Fumio Saito

According to the present invention, a process is provided for producing crystalline ceric oxide particles having a particle diameter of 0.005 to 5 &mgr;m, which comprises the steps of reacting a cerium (III) salt with an alkaline substance in an (OH)/(Ce ) molar ratio of 3 to 30 in an aqueous medium in an inert gas atmosphere to produce a suspension of cerium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension at a temperature of 10 to 95&deg; C. and at an atmospheric pressure.

Polishing abrasive of crystalline ceric oxide particles having surfaces modified with hydroxyl groups

A polishing composition for an aluminum disk includes water, an alumina abrasive agent and a polishing accelerator. The polishing accelerator is preferably basic aluminum nitrate. A process for polishing an aluminum disk using the polishing composition is also provided.

Polishing composition for aluminum disk and polishing process therewith

According to the present invention, a process is provided for producing crystalline ceric oxide particles having a particle diameter of 0.005 to 5 .mu.m, which comprises the steps of reacting a cerium (III) salt with an alkaline substance in an (OH)/(Ce.sup.3+) molar ratio of 3 to 30 in an aqueous medium in an inert gas atmosphere to produce a suspension of cerium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension at a temperature of 10 to 95.degree. C. and at an atmospheric pressure.

Process for producing crystalline ceric oxide particles and abrasive

A stable aqueous sol of colloidal zirconia having lowered surface activity and useful for polishing semiconductors and the like, is prepared by a process comprising calcining a colloidal zirconia having a specific surface area of 10 to 400 m.sup.2 /g, a particle size of 20 to 500 nm and a dehydratable water content of 4 to 15% by weight at 400.degree. to 1,000.degree. C. to form a calcined zirconia having a dehydratable water content of 0.1 to 2% by weight, and pulverizing the calcined zirconia in the presence of a water-soluble acid or alkali in water, to form the stable sol of colloidal zirconia having a specific surface area of 5 to 200 m.sup.2 /g, a particle size of 20 to 1,500 nm and a dehydratable water content of 0.1 to 3% by weight. The stable sol of colloidal zirconia has a ZrO.sub.2 concentration of 5 to 80% by weight.

Aqueous zirconia sol and method of preparing same

A sintered zirconia sheet is prepared by firing a green sheet of zirconia while placing at least one weight on the sheet to apply a load thereto. Preferably a weight made of a porous material having a porosity of 5 to 30% and having a weight per unit area W (g/cm.sup.2) and a surface area S (cm.sup.2) is placed on the sheet to apply a load per unit area G (g/cm.sup.2) to the sheet under the conditions: S.ltoreq.200, G.ltoreq.5, and W/G.gtoreq.0.5. Sintered zirconia sheets free of camber, distortion or cracking are obtained, particularly when their dimensions are at least 15 cm.times.15 cm and up to 0.5 mm thick.

Preparation of sintered zirconia body

A sheet-forming slurry composition is composed of zirconia powder, an organic binder, and a solvent. The zirconia powder contains 2 to 10 mol % of yttria in solid solution form and has a BET specific surface area of up to about 12 m.sup.2 /g and a mean particle size multiplied by the specific surface area of up to 3 .mu.m.m.sup.2 /g. The composition is formed into a green sheet having improved flexibility, binder removal capability, sinterability, and dimensional stability, which is then fired into a sintered part having improved denseness, gas barrier property, and surface smoothness.

Slurry composition and sintered part prepared therefrom

A stable basic zirconia sol can be prepared by adding to an acidic aqueous zirconia sol a dispersion stabilizer selected from the group consisting of a water-soluble organic acid having a hydroxyl group and a water-soluble organic compound having at least two hydroxyl groups, and thereafter adjusting the sol with a basic compound to pH 6 to 14.

Zirconia sol and method for making the same

A process for manufacturing fine zirconium oxide powder comprises adding a hydroxide of at least one metal selected from calcium, magnesium, yttrium and a lanthanide series element to a zirconia sol, which is dehydrated, dried and calcined. A zirconia sol prepared by hydrolyzing under heating an aqueous solution containing a zirconium salt, zirconium hydroxide or zirconia hydrate and then filtering the hydrolized aqueous solution through a ultra-filtration membrane is preferably used.

Growing community of inventors

Funabashi, Japan

Takao Kaga