Structure property relations in hot pressed 4.4 mol% calcia stabilized zirconia

4.4 Ca-TZP was hot pressed in the temperature range between 1200 and 1325 °C for 1 h at 60 MPa pressure. The material was characterized with respect to phase composition, mechanical properties and microstructure. The mechanical properties and phase composition of the Ca-TZP react very sensitively to changes in sintering temperature and average grain size. Fracture toughness continuously increases with sintering temperature from 5 MPa√m to 8.5 MPa√m while bending strength reaches an optimum of 1160 MPa combined with fracture toughness of 5 MPa√m at 1250 °C sintering temperature. The microstructure of the materials is ultrafine. The onset of monoclinic and cubic phase formation is observed at a sintering temperature of 1300 °C and a grain size of ∼140 nm. Indentation at elevated temperature was applied to suppress crack trapping which would lead to extreme overestimation of indentation toughness values.