Hydrothermal ageing of yttria-stabilised zirconia, sintered at 1300°C–1325°C: the effects of copper oxide doping and sintering time variations

Co-precipitated yttria-stabilised zirconia powders were doped with 0.05% wt of copper oxide (CuO). Samples were sintered at 1300°C–1325°C with holding times varying from 12 mins up to 4 hrs. The material was stable when exposed to hydrothermal ageing at 180°C, with only minimal signs of degradation in many cases for in excess of 3000 hrs. Excellent ageing resistance was observed for samples doped with 0.05 wt% of CuO, sintered at 1315°C for 12 mins which developed less than 1% monoclinic phase content, after 5000 hrs. Samples doped with 0.05 wt% of CuO, sintered at 1325°C for 12 mins, developed more than 50% of surface monoclinic phase content after 800 hrs of ageing, maintaining the same amount of monoclinic phase content for in excess of 3000 hrs. Plain samples sintered at 1325°C for 2 hrs developed more than 30% monoclinic phase content after 750 hrs. Doping with CuO improved the ageing resistance of the samples sintered at 1300°C–1315°C for 2 hrs and 12 mins holding times respectively.