Effects of Nano-Additives on the Structure and Properties of 99% Alumina Ceramics

99% alumina ceramics were sintered from the high-purity and superfine alpha-Al2O3 powders by the normal press sintering with the addition of nitrates of magnesium, chromium and copper as the nanometer additives. The influences of the nanometer additives on the sintering temperature, microstructure and the bending strength of the sintered alumina ceramics were investigated by SEM and other test methods in comparison with the micron oxide additives. Results showed that introducing the additives in the form of their nitrate provided well-dispersed oxides at the nanometer scales in the sintered bodies because of their being highly dispersed and high activity. Therefore, the nanometer additives performed better than the micron additives in reducing the sintering temperature and inhibiting the abnormal grain growth. As a result, the sintered alumina ceramics from the nano additives had a higher density and exhibited improved bending strength than those made from micron additives.