Characterization of transparent Al_2O_3 ceramics microstructure

Optical transparent polycrystalline Al2O3 ceramics were fabricated by conventional solid-state pressureless sintering processing using high-purity powder of Al2O3(99.9wt%purity). The effects of Y2O3 additive, sintering temperature and sintering holding time on the microstructure and optical properties of Al2O3 were investigated. The results indicate that small amounts of Y2O3 additiveinhibit the grain growth of the specimens, but the porosity increases with the increase of Y2O3 content.The optimum optical properties are obtained for the specimens sintered at 1800℃. The grain size increases and the porosity decreases with prolonging the sintering holding time.