Mechanical properties and dependence with temperature of tetragonal polycrystalline zirconia materials

Polycrystalline zirconia materials with a high content of metastable tetragonal phase have been obtained by pressureless sintering from experimental powders. Mechanical properties have been determined at room temperature and compared with similar materials. The fracture strength (σ /SUB f/ ) and fracture toughness (K /SUB 1c/ ) temperature dependence has been studied, in air environment up to 10000 C. Microstructure was studied by SEM examinations of fracture faces and TEM observations. Fracture toughness (of about 10 MPa √m at room temperature) decreases from 2000 C to 8000 C. The critical temperature (T /SUB c/ ) is estimated at 6000 C. We observe an important decreases of fracture strength at 2000 C. These mechanical properties are discussed on the basis of the stability of the tetragonal phase depending on additive content, grain size and temperature