Effect of Al2O3 Coating on Densification and Aging Sensibility of 3Y-TZP Ceramics

Al2O3 dopants in amount up to 1.5 wt% were coated on 3-mol-yttria-stabilized zirconia nanopowders adopting heterogeneous precipitation method. The influences of Al2O3 coating on the densification and the aging sensibility of 3Y-TZP were investigated. The process of densification was measured using a dilatometer. The density, the mean grain size and the mechanical properties of the densified 3Y-TZP were tested. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the microstructures of specimens. The results show that the densification of Al2O3-coated zirconia compacts was greatly enhanced by the coating process compared with the conventional co-precipitation process. Dense 3Y-TZP (>6.0 g/cm3) can be obtained using the Al2O3-coated starting powders by pressureless sintering at 1350∼1400 °C. In addition, the aging sensibility of 3Y-TZP is substantially decreased by adding Al2O3. This is probably attributed to the segregation of Al3+ at the grain boundaries of Al2O3-coated 3Y-TZP.