Aluminum oxide contains the elements aluminum and oxygen. If the alumina raw material is chemically treated to remove oxides such as silicon, iron, and titanium, the product obtained is highly pure alumina raw material, with an Al2O3 content generally above 99%. The mineral phase is composed of 40% to 76% γ- Al2O3 and 24% to 60% α- Al2O3 composition. γ- Al2O3 can be transformed into α- Al2O3 undergoes significant volume shrinkage simultaneously.