Lightweight high alumina brick usually refers to lightweight refractory products which contain at least 45% of Al2O3. Lightweight high alumina bricks are classified into two categories: one is ordinary light high alumina brick which adopts natural high alumina bauxite clinker as raw material, the other is premium lightweight high alumina brick which adopts fused or sintered Al2O3 as raw material, as its principal crystalline phase is corundum, it is also called lightweight corundum brick.
The usually used production method of lightweight high alumina brick is the foaming method. Ground high alumina clinker, binders(such as chamotte), and foaming agent are proportionally mixed to prepare a slurry, then green lightweight high alumina bricks are produced by casting method, and sintered at 1350~1500℃ high temperature.
The bulk density of lightweight high alumina brick is between 0.4~1.35g/cm3, porosity is between 66%~73%.
Crushing strength is between 1.3~8.1Mpa, thermal conductivity is between 0.291~0.582W/(m·K)(350℃).
Lightweight high alumina brick has high refractoriness, good thermal shock resistance, and so on.
|Bulk density g/cm3 ≤||1.0||0.9||0.8||0.7||0.6||0.4|
|Cold crushing strength Mpa ≥||3.9||3.4||2.9||2.5||2.0||0.8|
|Thermal conductivity W/(m·K)≤||0.50||0.45||0.35||0.35||0.30||0.20|
Lightweight high alumina bricks are usually used as high-temperature insulating lining of industrial kilns and furnaces. High-quality lightweight high alumina bricks can be directly used in working lining of industrial kilns, where contact with flame directly. But light high alumina brick is not suitable in places where molten slag corrosion exists. As lightweight high alumina bricks have good chemical stability at reduction atmosphere, so light high alumina bricks are usually used as insulating lining of kilns and furnaces which adopt H2 or CO as protection atmosphere. The max working temperature of high alumina brick is about 1350~1500℃, high purity lightweight corundum brick max. working temperature can reach 1650~1800℃.