Alumina ceramics are divided into high-purity type and ordinary type.

The sintering temperature of high-purity alumina ceramics is 1650-1990 ℃. Since the content of Al2O3 is more than 99.9%, the transmission wavelength is 1-6 μ  m。 Generally, molten glass is used instead of platinum crucible; Sodium lamp tube adopts light transmittance and alkali metal corrosion resistance; It can be used as integrated circuit substrate and high-frequency insulating material in electronic industry.

Ordinary alumina ceramics are divided into 99 porcelain, 95 porcelain, 90 porcelain and 85 porcelain according to alumina content. Sometimes, alumina ceramic series with Al2O3 content of 80% or 75% are also classified as ordinary alumina ceramic series. Among them, 99 alumina ceramic materials are used to make special wear-resistant materials such as high-temperature crucible, refractory furnace tube, ceramic bearing, ceramic seal and water valve plate; 95 alumina porcelain is mainly used as corrosion-resistant and wear-resistant parts; Due to the high strength of ceramics, some talc powder is often added, which can be sealed with molybdenum, niobium, tantalum and other metals, and some can be used as devices of electric vacuum devices.