The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 09, 2004
Filed:
Jul. 27, 1999
Hisashi Watanabe, Tsukuba, JP;
Yoshio Uchida, Tsukuba, JP;
Sumitomo Chemical Company, Limited, Osaka, JP;
Abstract
A process for producing a polycrystalline alumina sintered body which includes the steps of: subjecting alumina powder to ultrasonic irradiation, mechanical stirring not using a grinding medium, or ultrasonic irradiation and mechanical stirring not using a grinding medium, resulting in slurry dispersed in a solvent; drying and forming the slurry to produce a green body; and then sintering the green body in an air atmosphere at a temperature in the range of 1400° C. to 1800° C.; wherein the alumina powder has: a purity of 99.99 wt % or more and includes &agr; alumina particles having polyhedral shape, having substantially no red surface and a D/H ratio of from 0.5 or more to 3.0 or less; the number-average particle size of from 0.1 &mgr;m or more to 1.0 &mgr;m or less; and a D90/D10 ratio of 7 or less.