At present, it is divided into high-purity type and ordinary type. High-purity alumina ceramics are ceramic materials with an Al2O3 content of more than 99.9%. Because of its sintering temperature as high as 1650-1990°C and a transmission wavelength of 1-6μm, it is generally made into molten glass to replace platinum crucibles: use its light transmittance and It can resist the corrosion of alkali metal and be used as a sodium lamp tube; it can be used as an integrated circuit substrate and high-frequency insulating material in the electronics industry. Ordinary alumina ceramics are divided into 99 porcelain, 95 porcelain, 90 porcelain, 85 porcelain and other varieties according to the Al2O3 content. Sometimes those with Al2O3 content of 80% or 75% are also classified as ordinary alumina ceramic series. Among them, 99 alumina porcelain 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, etc.; 95 alumina porcelain is mainly used for corrosion-resistant and wear-resistant parts; 85 porcelain Because some talc is often mixed in, 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 devices.

China's alumina output is already the first in the world, but we have not yet taken advantage of the most lucrative high-end alumina. Although domestic alumina companies headed by Chinalco have been vigorously developing high-end alumina in recent years, the gap is still obvious. . It is often seen that some domestic companies are proud of exporting alumina to South Korea and Japan and earning tens of dollars more. In fact, they buy high-end alumina and earn several times as much as we do.

Alumina is a white crystalline powder, when the purity reaches more than 99.99%, it is called high-purity alumina. It has the advantages of excellent hardness, high brightness, electrical insulation, super wear resistance and high corrosion resistance. Generally, 3N high-purity alumina is mainly used in advanced ceramics; 4N is mainly used in phosphors; 5N is used in sapphire crystals, lithium battery separators, advanced ceramics, semiconductor materials, etc. Among them, alumina ceramic substrates used in 5G communication integrated circuits and high-purity alumina diaphragms for lithium batteries still rely on imports, while domestic market demand continues to rise.