High alumina refractory brick is referred to as high alumina brick, and its main mineral composition is mullite, corundum and glass phase. With the increase of AL₂O₃ content of high alumina bricks, the number of mullite and corundum phases also increases, the glass phase decreases accordingly, and the refractoriness and high temperature performance of the product increase. The increase in the number of glass phases and the decrease in viscosity will destroy the structure of high alumina bricks, especially the presence of KO and NaO not only reduces the temperature of the liquid phase, but also reduces the viscosity of the liquid phase, resulting in a rapid drop in the high temperature strength of the product. So is the refractory temperature of high alumina bricks related to the content of alumina in its raw materials?
The important working properties of high alumina bricks are the loading temperature and high temperature creep, and the loading softening temperature increases with the increase of the AL₂O₃ content of the product. High alumina bricks with an AL₂O₃ content below 70%, the softening temperature under load depends on the quantitative ratio between the mullite crystal phase and the liquid phase, and mullite-corundum products with an AL₂O₃ content between 70% and 90%, with the increase of AL₂O₃. The increase in load softening temperature is not obvious. This is because the FE₂O₃ and TiO₂ components in the raw material slightly increase with the increase of AL₂O₃, which changes the quantity and properties of the high-temperature liquid phase. The mullite crystal phase partially softens at high temperature, and the number of corundum Although there is an increase, the skeleton cannot be formed, resulting in no significant increase in the softening temperature under load. Only when the content of AL₂O₃ in the product is more than 90%, or even more than 95%, the main crystal phase in the product is corundum, the direct bonding rate between grains is significantly improved, and the liquid phase only exists in the gaps between the grains. The softening temperature was significantly increased.
