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Application of Silazane Polymers

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Polysilazane used for antioxidant properties of carbon materials

Carbon materials, such as graphite and carbon fiber, have the characteristics of low density, high performance, no creep, resistance to ultra-high temperatures in non oxidizing environments, good fatigue resistance, specific heat and conductivity between non-metals and metals, low coefficient of thermal expansion, and good corrosion resistance. They are essential materials in the field of high temperature resistance. However, the oxidation resistance of carbon materials is poor, and when the temperature reaches 400 ℃ or above in an air environment, there will be weight loss and a decrease in strength.

For carbon fiber reinforced composite materials, when the oxidation weight loss rate reaches 2% to 5%, the mechanical properties decrease by 40% to 50%, which seriously limits their application. Therefore, improving the antioxidant performance of carbon fibers is crucial. German researchers coated carbon fiber filaments with polysilazane and cured them at room temperature to form a coating. Through the isothermal weight loss assessment of fibers in a muffle furnace, it was found that the coating can effectively increase the oxidation temperature of carbon fibers, achieving a thermal stability temperature of 750 ℃. They further coated polysilazane onto carbon fiber coarse yarn and cured it at around 200 ℃. They found that the coating can also effectively improve the antioxidant performance and high-temperature stability of the fibers.

Polysilazane for High Temperature Protection of Metals
The high-temperature anti-corrosion and oxidation resistance of metals has always been an important topic in the industrial and scientific research communities. SiO2 or SiCN formed by the conversion of polysilazane has excellent corrosion resistance, and due to the polarity of Si-N in its structure, it is easy to bind with metal substrates, making it a good high-temperature and anti-corrosion coating material. At present, there are commercial high-temperature resistant coating materials that mainly use polysilazane as the main raw material, mainly used for exhaust pipes, pistons, heat exchangers, etc. in automobiles and trucks.

Polysilazane for high-temperature sealing of pores

When preparing ceramic components or coatings through inorganic sintering or plasma spraying methods, the material always has a certain porosity, which affects the material's airtightness and thus its high-temperature resistance. Therefore, it is necessary to carry out sealing treatment. 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 provide sealing at low temperatures, and lose their effectiveness after high-temperature decomposition. Inorganic adhesives are generally a combination of inorganic powders and organic adhesives, which have higher temperature resistance than organic sealing agents. However, as the temperature further increases, the gaps between inorganic nanoparticles after the adhesive decomposes will cause a decrease in the sealing effect. M. R. Mucalo et al. used polysilazane to coat alumina sheets, and after high-temperature cracking, a Si3N4/Si2N2O coating was formed on the surface of alumina. Scanning electron microscopy observation showed that the density of alumina was significantly increased, and the more coating times, the higher the density.

Due to the excellent temperature resistance of polysilazane, when appropriate fillers are added, the high-temperature insulation effect can be achieved. If hollow glass microspheres are added to polysilazane and sprayed onto the surface of the composite material, they can provide good high-temperature protection for the composite material after curing at 200 ℃.

Room termperature curing polysilazane, pls check IOTA 9150, IOTA 9150A
High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.  

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