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. 23, 2001
Filed:
Jun. 02, 1998
Applicant:
Inventor:
Osamu Yamamoto, Aichi, JP;
Assignee:
Other;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C01B 2/1064 ;
U.S. Cl.
CPC ...
C01B 2/1064 ;
Abstract
Turbostratic boron nitride (t-BN) powder having excellent sinterability. A mixture of boric acid anhydride and urea is charged in a reaction vessel together with alkali-borate, heated step by step in the vessel in an nonoxidizing gas atmosphere of one atmospheric pressure or above, and kept at a temperature from 850° C. to 950° C. to yield an intermediate product formal substantially of an amorphous boron nitride powder (first reaction step). Then the intermediate product is heated and kept at a temperature from 1200° C. to 1400° C. to crystallize crystalline t-BN, and the product is purified by washing with water and aqueous solution to obtain pure crystalline t-BN powder.