Colloidal processing for fine particles of Al₂O₃-15 vol% ZrO₂ system

Al₂O₃-15vol%ZrO₂ composites were produced by colloidal process. Dispersed suspensions consisting of α-Al₂O₃ and ZrO₂ fine powders were prepared by adjusting the pH value and salt concentration, or adding appropriate amounts of polyelectrolyte. The dispersion of powder particles was characterized by Theological measurement. In multicomponent particle systems, long range particle segregation occurs due to different particle size and specific gravity. The segregation decreases with increasing the salt concentration and/or solid content in the suspensions. The suspensions were consolidated by slip casting and cold isostatic pressing (CIP). They were sintered at temperatures from 1573K to 1793K for 2h in air. The microstmctures were observed by SEM. For the specimen sintered at 1673K, the density was more than 98% and the grain size of AljOj matrix was 0.42nm. At 1723K, the density was about 99.5% and the grain size was 0.59-0.70μm.