Alumina (Al2O3), the industrial Al2O3 is prepared from alumina (Al2O3, 3H2O) and hard alumina, and the Al2O3, which is high in purity, is usually prepared by chemical methods. Al2O3 has many isomorphic crystals, and there are currently more than 10 known types, mainly three types of crystal, namely gamma-al2o3, beta-al2o3, alpha-al2o3.Which structure is different, with different properties in high temperature above 1300 s almost entirely into alpha Al2O3.
