가장 많이 사용되고 안정적인 것은 α-알루미나이다. 최고 사용온도 1600C 정도인 우수한 내열성과 MOH's Hardness 9의 고경도를 가지며, 높은 전기절연성, 산․알칼리에 대해 안정적이다. 

α-Alumina는 내화물, 절연체, 스파크 플러그, IC기판과 팩키지, 분쇄․연마 재료, 내열․내화학성자기를 적용범위표에 나타냈다. α-결정크기, 입도분포와 불순물 등은 각 제품들의 특정한 요구에 맞춘 다양한 종류의 알루미나를 사용 할 수 있다.

A White crystalline powder, alumina is obtained by calcining aluminum hydroxide. Although there are many variations of alumina crystals, the one that is the stablest and accordingly most widely used is α-alumina. It has a high melting point, is themally stable, and ranks nest to silicone carbide, boron carbide and diamond in hardness. Moreover, it has high electric resistance and is stable against acids and alikalis.

α-alumina consequently serves in broad range of applications, including refractories, insulators. spark plugs. IC substrates and chemical resistane porcelains. Available are different types of alumina, each having its α-ultimate crystal size and particle size distribution and its impuritites content controlled to meet the particular requirements of such applications.