Superstoichiometric MgAl.sub.2 O.sub.4 spinel and use thereof, and process for the synthesis thereof

US5492871A · kind A · utility

Assignee

• Daimler-Benz AG · DE

Inventors

• Arnold Van Zyl · Ulm, DE
• Ping Wang · Huzhou City, CN

Key dates

• Filing date: Feb 22, 1994
• Grant date: Feb 20, 1996
• Expiry date: Feb 22, 2014

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C04B35/443
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A superstoichiometric MgAl.sub.2 0.sub.4 spinel, which can be used, for example, as material for a high temperature crucible, is synthesized by, producing a precursor mixture comprising intimately mixed oxides of the corresponding metals in the spinel. Magnesium is added in a superstoichiometric amount to the precursor mixture. Prior to spinel formation, from one to five percent by weight of a reactive salt containing fluorine and/or boron, based on the metal oxides of the spinel, are added to the precursor mixture, and the doped precursor mixture is mixed for from 0.5 to 3 hours. Finally, the mixed precursor mixture is heated for between 0.5 and 4 hours at a temperature between 1150.degree. C. and 1400.degree. C. to synthesize the Mg.sub.(1+x) Al.sub.2 0.sub.4 spinel which is superstoichiometric with respect to magnesium.