LIQUID-PHASE-SINTERING OF ALUMINA CERAMICS AND SINTERING KINETIC ANALYSIS

The effect of the addition of CuO and TiO2 on the sintering and microstructure of alumina ceramics was investigated. The sintering kinetics of alumina was also studied in the presence of liquid phase formed by CuO and TiO2. It was found that the sintering densification of alumina ceramic is greatly enhanced by the addition of CuO and TiO2. The sintering rate of alumina increases with the increase of the additive content. The density of alumina ceramic reaches a maximum when the content of additives CuO+TiO2 is 2% (in mass) and the mass ratio of CuO and TiO2 is 1/2. The grain growth of alumina is promoted by the additives, and the shape of the grains is equiaxed crystal. The sintering activation energy of alumina ceramics is 25.2 kJ/mol by determining according to isotrermal sintering kinetics. The results indicate that the sintering process is possibly controlled by the diffusion of Al3+ and O2- in the liquid phase.