Al2O3 has a high melting point, so the preparation of Al2O3 ceramics often requires the addition of sintering aids, which are dense through liquid phase sintering. This method usually promotes the sintering of Al2O3 ceramics. The liquid phase sintering of Al2O3 ceramics generates a liquid phase through a chemical reaction, promotes diffusion and viscous flow, to achieve the process of particle rearrangement and mass transfer, reduces the sintering temperature of Al2O3 ceramics, and accelerates effective sintering. Since there is no external driving force for atmospheric pressure sintering, it is very difficult to exclude all the pores inside the ceramic to reach the theoretical density. The special sintering process refers to the addition of sintering driving force during the sintering process of alumina ceramics to promote the densification of the ceramics. At present, the common special sintering processes mainly include hot pressing sintering, hot isostatic pressing sintering, microwave heating sintering, microwave plasma sintering, discharge plasma sintering, etc.