aluminaA white crystalline powder, alumina is obtained by calcining aluminum hydroxide. Although there are many variations of alumina crystals, the one that is the most stable and accordingly most widely used is α-alumina. It has a high melting point, is thermally stable, and ranks next to silicone carbide, boron carbide and diamond in hardness. Moreover, it has high electric resistance and is stable against acids and alkalis. α-alumina consequently serves in broad range of applications, including refractories, insulators, spark plugs, IC substrates and packages, grinding and polishing materials, and heat and chemical resistant porcelains. Available are different types of alumina, each having its α-ultimate crystal size and particle size distribution and its impurities content controlled to meet the particular requirements of such applications

Properties of α-alumina


Particle size distribution




Positions of aluminas


Sintering properties