Effect of Yttria and Yttrium-Aluminum Garnet on Densification and Grain Growth of Alumina At 1200°-1300°C

Abstract

Densification and grain growth of alumina were studied with yttria or yttrium-aluminum garnet (YAG) additives at the relatively low temperatures of 1200°–1300°C. Yttria doping was found to inhibit densification and grain growth of alumina at 1200°C and, depending on dopant level, had a lesser effect at 1300°C. At 1200°C, yttria inhibits densification more than it hinders grain growth. The rate of grain growth increases faster with temperature than the rate of densification. Alumina-YAG particulate composites were difficult to sinter, yielding relative densities of only 65% and 72% after 100 h at 1200° and 1300°C, respectively. Pure YAG compacts exhibited essentially no densification for times up to 100 h at 1300°C.