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. 15, 1983
Filed:
Sep. 16, 1981
Bernhard Schepers, Bergheim, DE;
Volker Nobbe, Neuhausen, CH;
Bernd Schroder, Cologne, DE;
Werner Borer, Flurlingen, CH;
Manfred Kullack, Bergheim, DE;
Swiss Aluminium Ltd., Chippis, CH;
Abstract
The invention describes a process for the production of coarse crystalline alumina from aluminum hydroxide, which after preparation by known methods is advantageously useful for abrasives, lapping and polishing purposes or for refractory materials. The process is characterized by aluminum hydroxide, either directly or after previous partial dehydration in the range 200.degree.-550.degree. C., being added with a mineralizer of compound type x(BF.sub.4).sub.n, wherein x stands for NH.sub.4 and metallic elements and n is for the formal valence of x, and subsequently is subjected to an elevated temperature treatment between 750.degree. C. and a value higher than the phase change temperature to .alpha.-Al.sub.2 O.sub.3.