Effect of Nb sub(2)O sub(5)/La sub(2)O sub(3) Additions on Mechanical Properties of Al sub(2)O sub(3) Ceramics Prepared by Microwave Sintering

The influence of Nb2O5 and La2O3 on the phase and microstructure evaluation and mechanical properties of composite ceramics sintered with 2.45 GHz microwave energy was investigated. The results showed that Nb2O5 could density the pure alumina with a lower sintering temperature and a short sintering time. Nb2O5 reacted with Al2O3 to form AlNbO4 completely and the amount of AlNbO4 increased with the increasing content of Nb2O5, distributing at the Al2O3 grain boundaries. The specimen doped with 10 Vol.% Nb2O5 sintered at 1500 [degrees]C exhibited plenty of columnar grains with draw ratio about 1:3. La2O3 reacted with Al2O3 to form LaAl11O18 completely, the specimen doped with 10 Vol.% and 15 Vol.% La2O3 sintered at 1500 [degrees]C exhibited plenty of columnar grains with draw ratio about 1:4. The existence of columnar grains enhanced the micro hardness and fracture toughness of composite ceramics.