Degussa Aktiengesellschaft

Evonik Degussa Gmbh

Herbert Habermann

Steffen Hasenzahl

Ina Hemme

Christoph Batz-Sohn

Martin Moerters

Uwe Diener

Ralph Hofmann

Christian Schulze-Isfort

Process for preparing an aluminum oxide powder which is present in the form of aggregated primary particles and comprises at least 85% by weight of alpha-aluminum oxide, in which an aluminum oxide powder which a) is present in the form of aggregated primary particles, b) is selected from the group consisting of gamma-aluminum oxide, theta-aluminum oxide, delta-aluminum oxide and/or X-ray amorphous aluminum oxide, and c) has a tamped density of at least 250 g/l, is subject to a heat treatment at 13000 C or more and subsequently milled. Aluminum oxide powder which can be obtained by this process. Aluminum oxide powder in the form of aggregated primary particles having a BET surface area of from 3 to 30 m2/g, in which the proportion of alpha-aluminum oxide is at least 85% by weight and the ratio dgo/dio of the weight distribution of the primary particles is at least 2.8. Use as constituent of fluorescent tubes.

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Silicon-titanium mixed oxide powder prepared by flame hydrolysis, having a ratio by weight of silicon dioxide/titanium dioxide, which is greater on the surface of the primary particles than that within the total primary particle. It is prepared by a flame hydrolysis process, in that a stream consisting of a vaporous titanium dioxide precursor and oxygen or an oxygen-containing gas and hydrogen, and a second stream consisting of a vaporous silicon dioxide precursor and a carrier gas consisting of oxygen, an oxygen-containing gas and/or an inert gas, are guided separately into the reaction chamber of a burner such as is known for the preparation of pyrogenic oxides, and are burnt here, the solid mixed oxide powder and hot gases are subsequently cooled, and the gases are separated from the solid. The powder may be used, for example, for the preparation of sunscreen preparations.

Silicon-titanium mixed oxide powder prepared by flame hydrolysis, which is surface-enriched with silicon dioxide, and the preparation and the use thereof

Iron oxide-silicon dioxide-titanium dioxide mixed oxide is produced by burning vaporizable compounds of iron, silicon and titanium together in a hydrogen/oxygen flame. The mixed oxides may be used as UV absorbers in cosmetics.

Iron oxide and silicon dioxide-titanium dioxide mixed oxide

Iron oxide-silicon dioxide-titanium dioxide mixed oxide is produced by burning vapourable compounds of iron, silicon and titanium together in a hydrogen/oxygen flame. The mixed oxides may be used as UV absorbers in cosmetics.

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Biebergemuend, Germany

Herbert Habermann