The main crystal phase of mullite bricks is mullite (3Al₂O₃·2SiO₂). However, ordinary high alumina bricks only have alumina content that meets the standard, and their crystal phase is usually composed of a mixture of corundum, mullite and glass.
In actual use, mullite bricks have significant advantages in thermal shock resistance and creep resistance. They have better volume stability under high temperature environments and are less prone to deformation and cracking problems.

Refractory castables are attracting more and more attention from customers, but they are often affected by the ambient temperature during use and undergo drastic changes. The thermal shock resistance of the castables reflects its value. Its thermal shock resistance is an important indicator for measuring the breakage resistance of the castables. It is the ability to counteract the loss caused by rapid changes in temperature during the use of the castables.