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:
Apr. 23, 1991
Filed:
May. 31, 1990
Helmut Scharf, Aurich, DE;
Huels Aktiengesellschaft, Marl, DE;
Abstract
1. Unstablized or stablized zirconium dioxide powder and processes for its preparation. 2.1 The use of aqueous solutions and the isolation of precipitates are substantial disadvantages of conventional processes for the preparation of zirconium dioxide powders. Furthermore, the products often do not have the desired flow properties, compression properties and sinter properties owing to the lack of microcrystallinity. 2.2 By melting zirconyl chloride optionally with a stabilizer or with a precursor of a stabilizer in the presence of a diol of the general formula HO--X--OH, in which X represents a saturated hydrocarbon radical having 2 to 5 carbon atoms, evaporating off water and hydrogen chloride, calcining the reaction product at elevated temperature in an oxygen-containing gas and optionally milling the calcined residue, an unstabilized or stabilized zirconium dioxide powder having good properties can be prepared without the use of disadvantageous process measures. 2.3 The unstabilized or stabilized zirconium dioxide powder is suitable for the production of sintered articles which can be subjected to high mechanical and/or thermal stresses.