Mechanical behaviour of partially stabilized zirconia crystals with terbia and ceria additives

Mechanical behaviour of partially stabilized zirconia crystals (PSZC) with terbia and ceria additives was investigated under bending and indentation conditions. Test specimens were oriented along the 010] direction and along the axis of crystal growth. The PSZC bending strength (σ_b) was dependent on the crystallographic orientation of the specimens. The specimen volume subjected to stress influenced the PSZC strength. The highest mechanical characteristics were measured for ceria-doped crystals (σ_b = 1.9 GPa, K_lc = 11.4 MPa m^1/2, E_d = 366 GPa). The failure process was studied on the Vickers indentation, with special emphasis put on the development and propagation of lateral cracks. Anisotropy of lateral cracks in the (100) plane associated with that of the elastic moduli was revealed. At the same time anisotropy of radial cracks and hardness was not found. A new version of the equation to evaluate the fracture toughness (K_c^v) on the Vickers indentation was derived. The K_c^v values calculated by this equation correspond to those (K_lc) obtained by an SENB method.