what is alumina ceramic?

Alumina ceramic is a kind of ceramic material with α-Al2O3 as the main crystalline phase. The content of Al2O3 in engineering practical application is generally between 75% and 99.9%. It is usually classified by the Al2O3 content in ingredients. The content of about 75% is called "75" porcelain, the content of 85% is called "85" porcelain, the content of 95% is "95" porcelain, and the content of 99% is "99" porcelain.