Low temperature preparation of Ce-TZP/Ba hexaaluminate composites

Composites consisting of Ce-TZP matrix and in-situ grown particles of barium hexaaluminate (BaAl12O19) as the second phase were prepared. To lower the sintering temperature and improve the microstructure of the composites, starting materials of two types of the second phase were used: mixed powders of BaCO3 and alpha-Al2O3, a and amorphous precursor powder. When the composites were prepared using the mixed powder of BaCO3 and larger alpha-Al2O3 (3.0 mu m) particles, aggregations of in-situ formed BaAl12O19 particles were observed in the Ce-TZP matrix. Although the formation temperature of BaAl12O19 decreased with decreasing average size of alpha-Al2O3 a particles, full dense composites were unobtainable, even at the sintering temperature of 1400 degrees C. To lower the formation temperature of the second phase further, amorphous precursor powder of BaAl12O19 was prepared using coprecipitation method. The composite prepared using the amorphous precursor powder was sufficiently densified at 1400 degrees C. The BaAl12O19 particles formed in the composite were finer than those prepared using the mixed powder of BaCO3 and alpha-Al2O3. (C)2011 The Ceramic Society of Japan. All rights reserved.