Nihon Cement Co., Ltd.

Yukio Kishi

Hideto Kamiaka

Ceramic substrate and producing process thereof, and a suction carrier

A titania ceramic body consists of a surface thereof not exceeding 35 pores per square millimeter. The titania ceramic body is made by preparing a titania powder having a purity of at least 99.8 wt % titania and an average particle diameter of 0.5 .mu.m, compacting the powder, sintering a compact at a temperature in the range for 1000.degree. to 1300.degree. C. in air or in a non-air surrounding gas under ordinary pressure to produce a sintered body, hot isostatic pressing treating the sintered body in argon at a temperature of from 800.degree. C. to below temperature carried out in above sintering step under pressure of at least 500 kg/cm2, and then grinding and polishing the hot isostatic pressing treated body.

Oxide ceramic sintered bodies

An oxide ceramic sintered body of a single component having a purity of at least 99% by weight of titania and a surface with a plurality of pores therein not exceeding 100 pores per square millimeter. The sintered ceramic body is made by preparing a raw titania powder having a purity of at least 99% titania by weight and an average maximum particle diameter of 1 .mu.m, compacting the titania powder to produce a compact, sintering the compact at a temperature in the range of about 1000.degree. C. to about 1300.degree. under ordinary pressure in air, or an inert or reducing atmosphere. The sintered ceramic body may be hot isostatic pressure treated below the sintering temperature in an inert atmosphere under a pressure of at least 500 kg/cm.sup.2 to further reduce the number of pores in the surface. The number of pores in the surface is determined by pressing the sintered ceramic body in sliding contacting engagement with a polishing buff sprinkled with carbon black so that the carbon black is forced into the pores to produce black spots on the surface representing the pores, and thereafter counting the black spots by inspecting the surface under a microscope to determine the number of pores.

Method for manufacturing oxide ceramic sintered bodies

A ceramic mirror having a surface flatness of no more than 1 .mu.m and/or a centerline average height of no more than 1 nm as measured by the laser interference method, is made from a titanium oxide powder having an average particle diameter of 0.5 .mu.m and a minimum purity of 99.8% by weight. The mirror also has a maximum amount of irregular reflection of incident light not exceeding 5% when the angle of projection is between 0.degree. and 90.degree. as measured by a colorimeter and is made by the process including forming a titanium oxide powder having a maximum average particle diameter of 0.5 .mu.m and a minimum purity of 99.8 wt. %, compacting the titanium oxide powder by cold isostatic pressing to produce a compact, sintering the compact of titanium oxide powder in air at a temperature of 1000.degree. C.-1300.degree. C. to produce a ceramic body, hot isostatic pressing the ceramic body after the sintering in an inert atmosphere at 800.degree. C.-1500.degree. C. under a minimum pressure of 500 kg/cm.sup.2, and machining the sintered body by surface grinding and lapping.

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Funabashi, Japan

Yukio Kishi