High alumina brick is a kind of refractory material, the main component of this refractory brick is Al2O3.
　　If Al2O3 content is higher than 90%, it is called corundum brick. Due to different resources, national standards are not completely consistent. For example, European countries set the lower limit of Al2O3 content for high-alumina refractories at 42%. In China, according to the content of Al2O3 in high alumina bricks, it is usually divided into three grades: Class I—Al2O3 content>75%; Class II—Al2O3 content is 60 to 75%; Class III—Al2O3 content is 48 to 60%.