Thermal Stability and Mechanical Properties of Surface CuO- and MgO-Modified Y-TZP Ceramics

The transformation stability (from tetragonal-to-monoclinic) and mechanical properties of 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystal) treated by CuO and MgO surface modification were investigated after annealing in water at 200°C. Surface CuO- and MgO-doped materials did not show an obvious decrease in mechanical properties after annealing in water. For surface CuO-doped 3Y-TZP, this behavior is attributed to re-distribution of ytrria by diffusion of Y3+ into the 3Y-TZP grains resulting in a higher stability of the tetragonal phase in the surface. However, compared with surface CuO modification, the effect of surface MgO modification is totally different. It is believed that the isolated nature of the tetragonal phase precipitated in the stable cubic zirconia matrix phase lead to less susceptibility to aqueous attack.