High alumina brick is a kind of refractory, the main component of which is Al2O3.

If Al2O3 content is higher than 90%, it is called corundum brick. Due to different resources, the standards of different countries are not completely consistent. For example, in European countries, the lower limit of Al2O3 content for high alumina refractories is 42%. In China, Al2O3 content in high alumina brick is generally divided into three grades: Grade I - Al2O3 content > 75%; grade II - Al2O3 content is 60-75%; grade III - Al2O3 content is 48-60%.
a. Fire resistance

The refractoriness of high alumina brick is higher than that of clay brick and semi silica brick, reaching 1750 ~ 1790 ℃, which belongs to high-grade refractories.

b. Load softening temperature

Because Al2O3 in high alumina products is high, the impurity quality is small, and the formation of fusible glass body is small, the load softening temperature is higher than that of clay brick, but because mullite crystal does not form network structure, the load softening temperature is still lower than that of silica brick.

c. Slag resistance

There are more Al2O3 in the high alumina brick, which is close to the neutral refractory and can resist the erosion of acid slag and alkaline slag. Because SiO2 is contained in the brick, the ability of resisting alkaline slag is weaker than that of resisting acid slag.
     It is mainly used for lining blast furnace, hot blast furnace, electric furnace top, blast furnace, reverberatory furnace and rotary kiln. In addition, high alumina brick is widely used as open hearth heat storage lattice brick, plug head for pouring system, nozzle brick, etc. But the price of high alumina brick is higher than that of clay brick, so it is unnecessary to use high alumina brick where clay brick can meet the requirements.

Project indicators	Specification value	Typical value
Al2O3　% ≥	40	42
Fe2O3　% ≤	2.5	2.0
bulk density　g/cm3 ≥	2.15	2.20
Apparent porosity　% ≤	22	20
Normal temperature withstand voltage　MPa ≥	29.4	36
Reborn line change　%	1400℃×2h -0.4～0.1 -0.3
Fire resistance　℃ ≥	1730	1750
Lotus soft 0.2MPa	1350	1400