Alumina ceramics are divided into two types: high purity and common type.
Al2O3 content of high purity alumina ceramics is 99. More than 9% of the ceramic material, due to the sintering temperature up to 1650-1990 ℃, the transmission wavelength of 1 ~ 6 microns, usually made from molten glass to replace platinum crucible; It is used as the sodium lamp tube with its transmittance and alkali resistance. In the electronics industry, it can be used as integrated circuit board and high frequency insulation material.
Ordinary alumina ceramics are divided into 99 porcelain, 95 porcelain, 90 porcelain and 85 porcelain in accordance with Al2O3 content. Sometimes the content of Al2O3 is in 80% or 75% of the ceramic series. Among them, 99 alumina ceramic materials are used to make high temperature crucible, furnace tube and special wear-resisting material such as ceramic bearing, ceramic seal and water valve, etc. Alumina porcelain is mainly used as corrosion resistant and wear-resisting parts; In China, due to the constant incorporation of the sliding stone, the electrical performance and mechanical strength can be improved with metal sealing, such as molybdenum, niobium and tantalum, and some used as vacuum devices.