Autocatalytic effect and microstructural development during ageing of 3 mol% Y₂O₃-TZP

The ageing kinetics of a 3 mol% Y-TZP are different at temperatures of 120-400°C in air and in ∼0·1 MPa water-vapour atmosphere. In air, a sigmoidal curve is observed while in water, a characteristic exponential curve is obtained. A new phase with d = 0·3027-0·2979 nm appeared after ageing in air and in a water-vapour atmosphere. An indication of the formation of a superlattice was observed by selected area diffraction pattern (SADP); it is suggested that the orthorhombic phase is responsible for the additional reflections.