Sintering Kinetics involving Densification and Grain Growth of 3D printed Ce-ZrO2/Al2O3

In this work, a systematic research is conducted into sintering kinetics of 3D printed Al2O3 and Ce–ZrO2/Al2O3 to evaluate the effect of CeO2/ZrO2 co-doping on the densification and grain growth. The sintering window shows microstructure confinement and full densification could be both realized at 1550 °C for Ce–ZrO2/Al2O3. The density curves versus time sintered at 1550 °C for the two material systems are very close and the highest relative density could be obtained at 1550 °C for both systems. The grain size exponent n is around 3 for all temperatures excluding 1550 °C for the un-doped Al2O3, indicating only grain boundary diffusion-controlled densification mechanism could be explained for the un-doped Al2O3, sintered at 1550 °C. The temperature dependent grain-growth constant K is one order of magnitude lower than that of the undoped Al2O3, which could fully manifest the grain growth retarding effect of Ce–ZrO2 co-doping. The activation energies obtained for the undoped Al2O3 and Ce–ZrO2/Al2O3 composites are 680.2 kJ/mol and 734.8 kJ/mol, respectively. The higher activation energy obtained for Ce–ZrO2/Al2O3 composite could be attributed either to the enthalpy for defect formation or to the presence of a liquid phase at grain interfaces in Ce–ZrO2/Al2O3.