Alumina ceramics are classified into two types: high purity type and normal type.
The high-purity alumina ceramics have a Al2O3 content of 99.9% or more. Since the sintering temperature is as high as 1650-1990 ° C and the transmission wavelength is 1 to 6 μm, the molten glass is generally used to replace the platinum crucible; Alkali metal corrosion resistance is used as a sodium lamp; it can be used as an integrated circuit substrate and high frequency insulation material in the electronics industry.
Ordinary alumina ceramics are classified into 99 porcelain, 95 porcelain, 90 porcelain, and 85 porcelain according to the Al2O3 content. Sometimes the Al2O3 content of 80% or 75% is also classified as a common alumina ceramic series. Among them, 99 alumina ceramic materials are used to make high temperature crucibles, refractory furnace tubes and special wear-resistant materials, such as ceramic bearings, ceramic seals and water valve sheets; 95 alumina ceramics are mainly used as corrosion-resistant and wear-resistant parts; In addition, due to the incorporation of part of talc, the electrical properties and mechanical strength are improved, and it can be sealed with metals such as molybdenum, niobium and tantalum, and some are used as electric vacuum device devices.