Microwave sintering and mechanical properties of Y-TZP/20 wt.% Al2O3 composites

Y2O3-stabilized t-ZrO2 (Y-TZP)/20 wt% Al2O3 composites were fabricated using microwave (MW) and conventional sintering techniques at temperatures in the 1200-1500 degrees C range. A considerable difference in the densification behavior between conventional and microwave sintered specimens up to 1300 degrees C was observed. The microwave sintered composites attain a bulk density similar to 97% theoretical density (T.D.) at 1200 degrees C, while the conventional fired materials attain only similar to 95% T.D. at 1500 degrees C. The average bulk density of the specimens, made by microwave sintering at 1500 degrees C, was similar to 99% T.D. At a given sintering temperature, microwave fabricated composites exhibited superior bending strength, fracture toughness and Vickers hardness when compared with conventionally sintered materials. For example, the composites fabricated at 1500 degrees C exhibited a K-1C of similar to 7.7 MPa root m and bending strength of similar to 990 MPa. For comparison, specimens made by conventional sintering exhibited K-1C of similar to 6.5 MPa root m and bending strength of similar to 820 MPa. This is due to a better densification of the MW-sintered specimens. (C) 2000 Elsevier Science S.A. All rights reserved.