High alumina brick is divided into four grades according to the aluminum content. The aluminum content of grade III high alumina brick is not less than 55%, that of grade II high alumina brick is not less than 65%, that of grade I high alumina brick is not less than 75, and that of super high alumina brick is more than 85. As for the shape of high alumina brick, in addition to standard high alumina brick, there are also general-purpose high alumina brick, also known as special-shaped high alumina brick. If the shape is very irregular, it is usually called special high alumina brick.
1. Wear resistance

2. Thermal conductivity:

Under the condition of unit temperature gradient, the heat flow rate per unit area through the material is related to the porosity

3. Impact resistance:

No need to explain. Good impact resistance and long service life

4. Slag resistance:

Resistance to slag erosion at high temperature without damage

Item	Index
Al2O3,%	≥78
Fe2O3， %	≤2.0
bulk densityBD，g/cm3	≥2.70
Apparent porosityAP，％	≤19
Normal temperature compressive strengthCCS，MPa	≥70
0.2MPa load softening start temperature ℃≥	≥1550
Change rate of reheating linePLC（1500℃×2h），％	－0.1～+0.6
purpose	Furnace top and other non-contact hot metal parts