Effect of preparation route on the properties of slip-casted Al2O3/YAG composites

Alumina composites containing 5, 10 and 20 vol.% YAG were produced by a slip-casting process. Two different routes for adding the YAG phase were chosen. Either by mixing of alumina with previously produced YAG powder or by coating of an adequate amount of yttria to form YAG precipitates during the calcining step. The mechanical properties of the sintered samples were measured and compared. Independent from the preparation route Al2O3/10 vol.% YAG composites showed best mechanical properties. Significant differences in the densification behavior appeared between the two different manufacturing technologies. The presence of intermediately formed phases like YAM and YAP during the powder preparation step of coated composites is probably the reason why mixed composites showed higher mechanical properties than coated composites.