Polysilazane is used for anti-oxidation of carbon materials:
Carbon materials, such as graphite and carbon fiber, have low density, high performance, no creep, ultra-high temperature resistance in non-oxidizing environment, good fatigue resistance, specific heat and electrical conductivity between non-metals and metals, low thermal expansion coefficient, It has the characteristics of good corrosion resistance and is an indispensable material in the field of high temperature resistance. However, the oxidation resistance of carbon materials is poor, and the phenomenon of weight loss and strength reduction will occur when the temperature in the air environment reaches above 400 °C.

For carbon fiber reinforced composites, when the oxidation weight loss rate reaches 2% to 5%, the mechanical properties decrease by 40% to 50%, which seriously limits its application. Therefore, it is very important to improve the antioxidant properties of carbon fibers. German researchers coated polysilazane on carbon fiber filaments and cured them at room temperature to form a coating. By examining the isothermal weight loss of the fiber in the muffle furnace, it is found that the coating can effectively increase the oxidation temperature of the carbon fiber, so that the thermal stability temperature of the carbon fiber reaches 750 ℃. They further coated polysilazane on carbon fiber rovings and cured them at about 200 °C, and found that the coating can also effectively improve the fiber's oxidation resistance and high temperature stability.

Polysilazane for metal high temperature protection:
The high temperature corrosion and oxidation resistance of metals has always been an important topic in the industry and scientific research circles. SiO2 or SiCN formed by the conversion of polysilazane has excellent corrosion resistance, and at the same time, due to the characteristics of Si-N polarity in its structure, it is easy to combine with metal substrates, so it is a good high-temperature anti-corrosion coating material. At present, there are commercial high-temperature resistant coating materials using polysilazane as the main raw material, which are mainly used for exhaust pipes, pistons, heat exchangers, etc. of automobiles and trucks.

Polysilazane for high temperature sealing:
When preparing ceramic parts or coatings by inorganic sintering or plasma spraying, the material always has a certain porosity, which will affect the air tightness of the material and thus affect its high temperature resistance, so it is necessary to seal the pores. Commonly used sealing agents are divided into two types: organic sealing agents and inorganic sealing agents. Organic sealing agents are mostly organic resins, which can only play a sealing role at low temperature, and lose their effect after high temperature decomposition. Inorganic adhesive is generally a combination of inorganic powder and organic adhesive. Its temperature resistance is higher than that of organic sealing agent, but the temperature further rises, and after the adhesive is decomposed, the voids between inorganic nanoparticles will cause the sealing effect to decline. M. R. Mucalo et al. used polysilazane to coat alumina flakes. After high temperature cracking, a Si3N4/Si2N2O coating was formed on the surface of alumina. Scanning electron microscope observation found that the density of alumina was significantly improved, and the more the coating times, the higher the density of alumina. The higher the density.

other:
Due to the good temperature resistance of polysilazane, the effect of high temperature heat insulation can be achieved when appropriate fillers are added. For example, adding hollow glass microbeads to polysilazane and spraying it on the surface of the composite material, after curing at 200 ℃, can play a good high temperature protection effect on the composite material.