The effect of transition metal oxide doping on the sintering behaviour of yttria-stabilised tetragonal zirconia

The effect of small amounts (0.2 wt% and 0.5 wt%) of transition metal oxide (CuO) doping on the sintering behavior of 3 mol% yttria-stabilized zirconia (Y-TZP) was investigated over the temperature range of 1250 degrees C to 1500 degrees C. Sintered samples were characterized to determine the phase present, relative density, microstructural evolution and Vickers hardness. The studies revealed that the addition of 0.2 wt% CuO dopant was most effective in enhancing the densification of the Y-TZP in particularly at low temperatures below 1350 degrees C. The phase analysis revealed that the tetragonal phase was disrupted as evident from the high monoclinic phase formation in the 0.5 wt% CuO-doped zirconia. This phenomenon was associated with mechanism involving transient liquid phase which believed to have destabilized the tetragonal structure. Nevertheless, the study revealed that compared to the undoped Y-TZP, the sample with addition of 0.2 wt% CuO resulted in enhanced hardness and finer grain sizes when sintered at relatively low temperatures.