Vereinigte Aluminium-werke Aktiengesellschaft

Jorg F Greber

Gunter Winkhaus

Heidemarie Melas

A method is disclosed for manufacturing transparent aluminum oxide ceramic articles by sintering dry-pressed acid-containing aluminum oxide monohydrate in vacuo or in hydrogen. The method includes obtaining the acid-containing aluminum oxide monohydrate by peptisization of aluminum alkoxide with a mixture of water and acid vapor, with the acid bound to the formed monohydrate by electrostatic force. Such attachment allows ease in separation of the monohydrate crystals in water due to the polarizing effect of the acid. Subsequently, the acid-containing aluminum oxide monohydrate is gelled and dried, with the product, having an acid content of from 12 to 25%, being suitable for forming transparent ceramic articles without requiring calcination.

Method for the manufacture of transparent aluminum oxide ceramic

The present invention relates to a modified form of alumina hydrate filler, thermosetting and thermoplastic compositions having improved workability and mechanical properties containing such filler and methods of manufacturing such modified alumina hydrate filler. More specifically, the invention provides for the admixture of modified alumina hydrate crystals with a resinous composition in which the individual alumina hydrate crystal edges are substantially rounded, have a mean crystal size of less than about 35 microns and less than about 0.1% by volume of alumina hydrate crystals have a diameter of less than 2 microns. The resulting compositions have improved viscosity properties and exhibit good bending strength and flame retardant characteristics.

Growing community of inventors

Bonn, Germany

Jorg F Greber