Effect of Zirconia Substitution on Structural and Mechanical Properties of ZTA Composites

Zirconia Toughened Alumina (ZTA) composites are attractive structural materials, which combine the high hardness and elastics modulus of the alumina matrix with additional toughening effects, due to the zirconia dispersion. In the present study, ZTA composites containing different amounts of zirconia (in the range 0-16 wt %) were prepared by slurry method and sintered at 1450oC and 1550oC for two hour. Microstructure of the composites was observed using scanning electron microscopy and phase content was detected by means of X- ray diffraction. Mechanical properties such as hardness, elastic modulus and flexural strength were measured. Density was increased with the increase of zirconia content for both sintering temperature, while grain size and elastic modulus was decreased with the same change of zirconia content. Hardness and flexural strength were carried out using the Vickers indentation and were discussed as a function of the ZrO2 content and sintering temperature. The toughening effect is attributed mainly to the zirconia t→m phase transformation. About 61% more flexural strength was found for 16 wt % ZTA composites when compared to the pure alumina.