Mullite is a high-quality refractory raw material, which is rare. Mullite is a mineral produced by aluminosilicate at high temperatures, and mullite is formed when artificially heating aluminosilicate. Natural mullite crystals are elongated needle-like and radiate clusters. The mullite mine is used to produce high temperature refractories. It is widely used as a thermal barrier coating in C/C composites and is widely used. The mullite AI2O3-SiO2 element system is a stable binary solid solution under normal pressure. The chemical formula is AI2O3-SiO2. Natural mullite is very rare, and is usually synthesized by sintering or capacitance.