Sintering kinetics at constant rates of heating: Effect of alumina on the initial sintering stage of Yttria-stabilized cubic zirconia powder

The sintering behavior of 7.8 mol% Yttria-stabilized cubic stabilized zirconia (Y-CSZ) powders was investigated, with emphasis on the effect of Al2O3 addition at the initial sintering stage. The shrinkage of powder compact was measured under constant rates of heating (CRH). The powder compact with 0.25 mass% Al2O3 enhanced the densification rate with elevating temperature. The activation energies at the initial stage of sintering were determined by analyzing the densification curves. The activation energy of powder compact with Al2O3 was lower than that of powder compact without Al2O3. The diffusion mechanisms at the initial sintering stage were determined by the new analytical method applied to the CRH data. This analysis exhibited that the diffusion mechanism changed from grain boundary to volume diffusions (VD) by Al2O3 addition. It is therefore concluded that the Al2O3 addition enhances the densification rate because of decreasing the activation energy of VD at the initial sintering stage.