Composition design and mechanical properties of mixed (Ce,Y)-TZP ceramics obtained from coated starting powders

The microstructure and mechanical properties of a selection of ceramics with compositions in the low ceria and yttria corner of the ZrO2–CeO2–Y2O3 system were investigated and evaluated. The calculated isothermal section of the ZrO2–CeO2–Y2O3 system at 1450 °C was used to define the CeO2 content range of interest resulting in an optimum amount of tetragonal ZrO2 phase for TZP ceramics with an overall yttria content of 2 and 1 mol%. Pure monoclinic ZrO2 starting powder was coated with the appropriate amount of yttria and ceria stabiliser by means of a suspension coating technique and pressureless sintered in air at 1450 °C. The indentation toughness and Vickers hardness were evaluated as a function of the sintering time, grain-size and stabiliser content. An excellent fracture toughness of 13–15 MPa m1/2 was obtained for ZrO2 ceramics with 1 mol% Y2O3 + 4 mol% CeO2, sintered for 1–4 h at 1450 °C.