Sintering of 3 mol % Y₂O₃-TZP and its fracture after ageing treatment

TZP ceramic of 99.7% theoretical relative final density was obtained by pressureless sintering a commercial co-precipitated 3 mol % Y₂O₃-ZrO₂ powder at 1400° C for 10 h. Fracture surfaces of the aged material revealed that the fracture of TZP ceramic was typified by an intergranular mode in areas where the phase was mainly tetragonal, whereas the transgranular mode was found predominantly in the area containing more monoclinic phase. Microcracks induced by the (t) → (m) transformation provided short paths for water to accelerate the property degradation of TZP upon low-temperature ageing in a humid atmosphere.