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:
Oct. 24, 2000
Filed:
Dec. 28, 1998
Yong Kee Baek, Daejon, KR;
Hyoun-Ee Kim, Seoul, KR;
Won Ho Lee, Seoul, KR;
Ki Min Lee, Seoul, KR;
Seung Su Baek, Daejon, KR;
Eul Son Kang, Daejon, KR;
Agency for Defense Development, Daejon, KR;
Abstract
A silicon nitride sintered body is obtained by mixing 2.about.16 wt % of Yb.sub.2 O.sub.3 as a sintering additive with Si.sub.3 N.sub.4 powders including unavoidable impuirities, pressing the mixed powder into a desired form, and gas-pressure sintering the thusly pressed form, whereby an inner region of the sintered body has a fine microstructure, and an outer region thereof has a mixed microstructure in which elongated grains and fine grains co-exist and a method for manufacturing a silicon nitride sintered body, includes the steps of: adding and mixing 2.about.16 wt % of Yb.sub.2 O.sub.3 powder as a sintering additive into a silicon nitride (Si.sub.3 N.sub.4) powder; ball-milling the mixed powder to obtain a slurry; drying and classifying the slurry; press-forming the resultant powder in a die uniaxially and isostatically; and gas-pressure sintering the resultant compact body at a temperature in the range of 1800.about.2000.degree. C., whereby an inner region of the resultant sintered body has a fine microstructure, and an outer region of the resultant sintered body has a mixed microstructure in which elongated grains and fine grains co-exist.