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:
Mar. 26, 1991
Filed:
Jan. 04, 1990
Issei Hayakawa, Nagoya, JP;
Shigenori Ito, Kasugai, JP;
NGK Insulators, Ltd., Nagoya, JP;
Abstract
A homogeneous Si.sub.3 N.sub.4 sintered body is produced having a proportion of a grain boundary crystalline phase to the whole grain boundary of 50% or less, maximum pore diameter of 10 .mu.m or less and a porosity of 0.5% or less. A process for manufacturing each an Si.sub.3 N.sub.4 sintered body is, in conventional processes wherein a starting material for Si.sub.3 N.sub.4 is mixed with a sintering aid, pulverized, granulated, then molded and subsequently fired, characterized in that a temperature lowering rate from a firing temperature to 1,000.degree. C. is made to be 30.degree. C./min. Another process of the invention is, in the above conventional process, characterized in that Si.sub.3 N.sub.4 containing at least 90% of .alpha.-Si.sub.3 N.sub.4 as a starting material and a sintering aid, both having an average grain diameter of 1 .mu.m or less, are used, the granulated powder is once forcedly dried and then, if required, water is added, before the molding and firing.