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:
Feb. 18, 2003
Filed:
Sep. 03, 1997
Masahide Mohri, Ibaraki, JP;
Yoshio Uchida, Ibaraki, JP;
Yoshinari Sawabe, Ibaraki, JP;
Hisashi Watanabe, Ibaraki, JP;
Sumitomo Chemical Co., Ltd., Osaka, JP;
Abstract
A process for producing &agr;-alumina containing &agr;-alumina single crystal particles characterized in that at least one of a transition alumina and transition alumina precursor is calcined in an atmosphere containing at least 1% by volume of hydrogen chloride at a temperature of not less than 600° C., preferably from 600 to 1,400° C., and more preferably from 800 to 1,200° C. Aluminum hydroxide, alum, aluminum sulfate, etc. are used as the alumina raw material capable of being converted to transition alumina on heating. &agr;-Alumina comprising octahedral or higher polyhedral &agr;-alumina single crystal particles have a high alumina purity above a given level, are fine and homogeneous, have a narrow particle size distribution, are not agglomerated particles, and can be obtained from raw materials of various kinds, purities, shapes, sizes, and compositions.