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°C range. A considerable difference in the densification behavior between conventional and microwave sintered specimens up to 1300°C was observed. The microwave sintered composites attain a bulk density ∼97% theoretical density (T.D.) at 1200°C, while the conventional fired materials attain only ∼95% T.D. at 1500°C. The average bulk density of the specimens, made by microwave sintering at 1500°C, was ∼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°C exhibited a KIC of ∼7.7 MPa m and bending strength of ∼990 MPa. For comparison, specimens made by conventional sintering exhibited KIC of ∼6.5 MPa m and bending strength of ∼820 MPa. This is due to a better densification of the MW-sintered specimens.