Many ceramic and metal materials will be damaged if they are in high temperature, reduction, oxidation and other environments for a long time. Such problems can be solved by coating the surface of the material with a compound coating material that can remain stable in the use environment. Mullite has stable chemical properties, good corrosion resistance, and excellent performance, which makes it widely used in compound coatings and other aspects.

Because mullite has excellent high-temperature mechanical properties, chemical stability, creep resistance, thermal shock stability, low thermal expansion coefficient, etc., it is widely used in the field of high-temperature thermal materials. However, mullite has no dislocation slip system. When the external load exceeds a certain limit, more microcracks will be generated inside to consume energy, causing catastrophic damage to mullite ceramics. Therefore, how to toughen mullite materials has become a hot topic in recent years.

Researchers at home and abroad have conducted a lot of research on mullite composites and have achieved certain results in the field of mullite toughening. Mullite composites include mullite matrix, mullite fiber, etc. Mullite composites can reduce the inherent brittleness of mullite material systems and improve their strength and toughness. After years of efforts, the thermodynamic behavior of mullite-based composite materials has been improved by particle reinforcement (SiC, ZrO2) or flake reinforcement, and some progress has been made in the toughening of mullite.