The sintering behaviors of high purity Al2O3 ceramics prepared from a submicron-scale powder were investigated. The effects of ball milling on the evolution of alumina powders' compressibility, sinterability, grain growth and microstructure during sintering process were studied. It was observed that the relative density of the Al2O3 ceramics increased with increasing compaction pressure on the green compacts and the sintering temperature. However, the applied pressure had less influence on the relative density of ceramics sintered from green compact with narrower size distribution and finer powder. The fast grain growth of the Al2O3 ceramics occurred in different temperature ranges and was influenced by milling time and forming methods. The effect of milling on the microstructural evolution of alumina during sintering was also discussed.

Keywords: Sintering, High purity alumina, Submicrometer powder, Microstructure.