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:
Jun. 30, 1992
Filed:
May. 23, 1991
Naoto Hirosaki, Yokohama, JP;
Akira Okada, Yokohama, JP;
Nissan Motor Co., Ltd., Yokohama, JP;
Abstract
A sintered silicon nitride which comprises silicon nitride as a main component and having an oxygen content not more than 1% by weight and a bulk density not less than 95% of the theoretical density thereof. The sintered silicon nitride is produced as follows: Silicon powder and the oxide of at least one element selected from the group IIIb of a periodic table of the elements are mixed to obtain a mixture, in which the total amount of the oxide is not larger than 4% by weight of the mixture. The mixture of the silicon powder and the oxide is compacted to form a compact. The compact is nitrided in the atmosphere of nitrogen at a temperature of not higher than 1500.degree. C. to have a silicon remaining rate ranging from 2 to 20% by weight. Then, the compact is fired in the atmosphere of nitrogen at a pressure of not less than 1 atmospheric pressure and at a temperature ranging from 1800.degree. to 2200.degree. C. to obtain the sintered silicon nitride having a bulk density not less than 95% of the theoretical density thereof.