Process and apparatus for the preparation of pulverulent metal oxides for ceramic compositions

US5219829A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Gerd Bauer · Kleinostheim, DE
• Matthias Kuntz · Seeheim-Jugenheim, DE
• Ingrid Grobelsek · Darmstadt, DE
• Dirk Reyermann · Darmstadt, DE
• Gunter Nimtz · Frechen, DE

Key dates

• Filing date: Nov 4, 1991
• Grant date: Jun 15, 1993
• Expiry date: Nov 4, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S505/737
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The invention relates to a process and an apparatus for converting metal nitrate or mixed metal nitrate solutions into the corresponding metal oxides in a microwave field. The invention consists in heating, while the feed stream is being metered in, in such a manner that the solvent always evaporates within seconds and the decomposition product is obtained as a porous, sponge-like, purely oxidic material, which can be ground easily to give a powder having particle sizes of 0.5 to about 10 .mu.m. The controlled metering in of the nitrate solution simultaneously makes it possible to control the reaction temperature below the sintering temperature of the powder. The reaction of the nitrate starting solution can take place continuously/batchwise in a reaction flask or continuously in a rotating reaction pipe, which is preferably charged with grinding balls, which possibly exert a reaction-activating effect similar to that exerted very particularly by the metal oxide sponge formed during the reaction.