Which expansion coefficient is larger, corundum brick or mullite brick?
The high-temperature expansion of refractory bricks refers to the high-temperature performance of the bricks, and the expansion coefficient refers to the relative change ratio of refractory bricks when the temperature rises. Corundum bricks and mullite bricks are both high-end materials in the field of refractory materials and also belong to the alumina series. In comparison, corundum firebricks have a smaller expansion coefficient than mullite firebricks. Corundum refractory bricks have high melting point, stable high temperature performance and good wear resistance.
1. Mullite is similar to high alumina refractory bricks
Mullite bricks are similar to high alumina refractory bricks. There are two forms of mullite, one is mullite produced from clinker with high aluminum content at high temperature, and the other is mullite refractory bricks made of mullite that is shaped and fired at high temperature. In particular, refractory bricks with added mullite have a sintering temperature above 1700°C, can form a protective film at high temperatures, and have good flexibility.
2. The thermal expansion coefficients are different
Refractory bricks will expand in volume after heating, but the thermal expansion coefficients are also different depending on the composition of different minerals. The thermal expansion of clay bricks, high alumina bricks, magnesia bricks, etc. is relatively large, but the expansion coefficient of silica bricks is larger due to polycrystalline transformation.
The larger the thermal expansion coefficient, the less controllable the size of the refractory bricks, and the thermal stability will also be affected. The greater the thermal expansion coefficient, the greater the internal stress generated by the refractory bricks after heating, and they are easily damaged when the temperature changes rapidly.
3. The expansion coefficient is one of the important indicators of refractory bricks
The smaller the expansion coefficient, the smaller the volume change caused by the crystallization, crystal transformation and continuous sintering of refractory bricks under the action of high temperature. The expansion coefficient is one of the important indicators of refractory bricks. The volume of refractory bricks will change due to the influence of temperature during use. It will seriously affect the compactness of the size of the refractory bricks. Under normal circumstances, when laying refractory bricks, expansion joints must be left according to the bricks of different materials. If the expansion coefficient is too large and not handled in time, the furnace body will crack due to brick expansion, affecting use.
There are many types of refractory bricks with different expansion coefficients. Comparing corundum bricks and mullite bricks, the expansion rate of corundum firebricks is smaller than that of mullite fire bricks.
