One of the important working properties of high alumina refractory brick is the structural strength at high temperature, which is usually evaluated by the load softening deformation temperature. In recent years, its high temperature creep properties have also been measured to reflect its high temperature structural strength. The test results show that the load softening temperature varies with Al2O3. The content increases with the increase.

For refractory bricks with Al203 content below 70%, the load softening temperature depends on the quantity ratio between the crystalline phase and the liquid phase of mullite, and increases with the quantity of mullite. The quantity and properties of liquid phase have obvious influence on the softening temperature under load. Therefore, reducing the content of impurities in raw materials is conducive to improving the load softening temperature and high temperature creep.

For mullite and corundum refractory bricks with 70% to 90% Al203 content, the increase of Al203 content is not significant. This is due to the partial softening of mullite crystals at high temperatures, as well as a slight increase in the number of flux impurities that interact with the glass crystals, especially the Ti02.Fe203 component increases slightly with the increase in the content of Al203 in the raw material, changing the number and properties of the high-temperature liquid phase.

Due to the large increase of Ti02.Fe203 in the glass phase, the amount of glass phase increases and the viscosity decreases. This is the crux that obviously affects the softening temperature under load and the creep at high temperature. Only when the refractory brick transition to almost entirely composed of corundum, that is, the refractory brick Al203 content of more than 95%, the high temperature structure strength has been significantly improved.

The thermal shock resistance of high alumina refractory brick is worse than that of clay brick, which is closely related to the mineral composition in refractory brick. High aluminum bricks such as I and II are worse than high aluminum bricks such as Ⅲ. In the production, the thermal shock resistance of refractory bricks is often improved by improving the particle structure characteristics of refractory bricks or adding a certain amount of synthetic cordierite (2Mg0.2AI203.5Si0z) and other minerals in the ingredients:

The slag resistance of high aluminum refractory brick increases with the increase of Al203 content. However, its corrosion resistance to alkaline slag is lower than that of alkaline refractory. The decrease of impurity content is conducive to the improvement of slag resistance. At the same time, improving the density of refractory bricks: reducing the porosity is also an effective measure to improve its slag resistance.

High alumina brick has higher thermal conductivity than clay brick, which is related to the decrease of glass phase and the increase of mullite crystal or corundum crystal in high alumina refractory brick.