Alumina ceramic is a kind of ceramic material with alumina (Al2O3) as the main body, which is used in thick film integrated circuit. Alumina ceramics have good conductivity, mechanical strength and high temperature resistance.
      At present, alumina ceramics are divided into high-purity type and common type. High purity alumina ceramics with Al2O3 content of more than 99.9% are generally made into molten glass to replace platinum crucible because of its sintering temperature of 1650-1990 ℃ and transmission wavelength of 1-6 μ M. it can be used as sodium lamp tube by its light transmittance and alkali resistance. It can be used as integrated circuit substrate and high frequency insulating material in electronic industry.
      According to the content of Al2O3, ordinary alumina ceramics can be divided into 99, 95, 90 and 85 ceramics. Sometimes, alumina ceramics with Al2O3 content of 80% or 75% can also be classified as ordinary alumina ceramics. Among them, 99 alumina ceramic materials are used to make high temperature crucible, fire-resistant furnace tube and special wear-resistant materials, such as ceramic bearing, ceramic seal and water valve plate, etc.; 95 alumina ceramic is mainly used as corrosion-resistant and wear-resistant parts; 85 ceramics can be sealed with molybdenum, niobium, tantalum and other metals, and some of them can be used as electric vacuum devices.