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:
Aug. 22, 2000
Filed:
Jun. 23, 1997
Masahide Mohri, Ibaraki, JP;
Norio Matsuda, Ibaraki, JP;
Shinichiro Tanaka, Ibaraki, JP;
Yoshio Uchida, Ibaraki, JP;
Yoshinari Sawabe, Ibaraki, JP;
Hisashi Watanabe, Ibaraki, JP;
Hiroshi Ogawa, Ibaraki, JP;
Sumitomo Chemical Co., Ltd., Osaka, JP;
Abstract
Alpha alumina powder is produced by granulating at least one alumina starting material selected from group consisting of transition alumina and alumina compound to obtain particles and calcining the particles in a halogen-containing atmosphere which comprises a hydrogen halide gas, a halogen gas or a mixture of a halogen gas and steam and contains at least 0.1 % by volume of at least one halogen-containing gas selected from the group consisting of hydrogen halide gas and halogen gas. By granulating the alumina starting material powder in the form of particles to increase a bulk density and calcining them in the presence of halogen, .alpha.-alumina powder having a regulated particle size and shape and a narrow particle size distribution and containing fewer agglomerated particles is produced at a high calcining efficiency.