At present, alumina ceramics are divided into high-purity type and ordinary type. High purity alumina ceramics are ceramic materials with Al2O3 content of more than 99.9%. Because its sintering temperature is as high as 1650-1990 ℃, the transmission wavelength is 1 ~ 6 μ m. Generally, molten glass is made to replace platinum crucible: it is used as sodium lamp tube by its 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, 85 porcelain and other varieties according to different Al2O3 content. Sometimes those with Al2O3 content of 80% or 75% are also classified as ordinary alumina ceramics 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 plates; 95 alumina porcelain is mainly used as corrosion-resistant and wear-resistant parts; Because some talc is often mixed in 85 porcelain, the electrical properties and mechanical strength are improved. It can be sealed with molybdenum, niobium, tantalum and other metals. Some are used as electric vacuum devices.

 

Alumina crucible has a wide range of uses. It can be used for the analysis of metal and non-metal samples and melting materials in various laboratories. It can also be used for burning color materials, color agents, frits, pigments, luminescent materials, etc. in shuttle kilns and pusher kilns, and for adjusting the formula of small experimental kilns and experimental electric furnaces; Smelting metals, precious metals and optical glass, used for the analysis and firing of rare earth and other mineral raw materials, and the firing of high-temperature products such as ceramic powder.