Showa Denko K.k.

Showa Denko Kabushiki Kaisha

Matsushita Electric Industrial Co., Ltd.

Tanken Seiko K.k.

Fumio Kagawa

Toshiaki Sakaida

Norimichi Aoki

Yoshihiko Yuzawa

Shin'ichi Horie

Fumio Iriko

Yutaka Matsuzaki

A silicon carbide sintered body for a mechanical seal which has independent pores having an average pore diameter of from 10 to 40 .mu.m and a porosity of from 4 to 13 vol %. The mechanical seal includes a stationary sliding ring and a rotary sliding ring, with at least one of the rings being the silicon carbide sintered body. The silicon carbide sintered body is preferably made of .alpha.-silicon carbide powder.

Silicon carbide sintered body for mechanical seal and mechanical seal

A mold for molding an optical disc includes a first mold member having a recess, and a second mold having a body and a plate-like sintered ceramic member secured to the body and having a flat seat surface. The recess and the flat seat surface jointly provides a mold cavity when the first and second mold members are mated together. A disc-shaped thin stamper is adapted to be seated on and detachably secured to the flat seat surface. The ceramic member is made of a ceramic material having Rockwell hardness (A-Scale) of not less than 90, so that the flat seat surface is not subjected to undue damage for a prolonged period of time.

Mold for molding optical disc

A glass-grinding sheet is prepared by a process wherein 100 wt. parts of a powdery metal composition consisting of, based on the weight of the composition, 80-96.8% copper, 3-15% of tin and/or zinc, and 0.2-5% of nickel and/or titanium, are mixed with 0.5-30 wt. parts of a diamond powder; the mixture is sintered; and then, the obtained sintered body is rolled into a sheet of the desired thickness. The powdery metal composition is either a copper alloy consisting of (a) copper, (b) tin and/or zinc and (c) nickel and/or titanium, or a mixture of a copper alloy consisting of (a) copper and (b) tin and/or zinc, with (c) nickel and/or titanium.

Grinding sheet and process for preparing same

An abrader for use in mirror polishing of glass comprises a porous cured unsaturated polyester resin and zirconium oxide or cerium oxide or red iron oxide. Desired mirror polishing of glass is effected by grinding the glass surface with this abrader under continued supply of water or a cutting oil to the interface of grinding.

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Shiojiri, Japan

Fumio Kagawa