Resistant Coatings
Drying shrinkage problem
During the transformation from sol to gel and the subsequent drying process, due to the volatilization of solvents and other reasons, gel will shrink significantly, which is easy to lead to cracks in the coating. This will not only affect the appearance integrity of the coating, but also damage the continuity of the coating, reduce the density of the coating, and thus weaken its high temperature resistance and protection ability to the substrate.
Long preparation cycle
The whole sol gel preparation process includes sol preparation, gel formation, drying, curing and other links, and each link often takes a certain amount of time to ensure full reaction, complete solvent volatilization, etc. Compared with some relatively fast preparation methods such as thermal spraying, the sol gel method takes a long time as a whole, which is not conducive to efficient and large-scale production.
Relatively high cost
On the one hand, the precursor materials used, such as metal alkoxides, are usually expensive; On the other hand, this method has strict requirements for the preparation environment, such as being carried out under relatively clean and well controlled temperature and humidity conditions. The use of some organic solvents and subsequent treatments also increase the cost input, resulting in higher overall costs compared to some traditional preparation processes, which limits its large-scale use in some cost sensitive application scenarios.
Limited coating thickness
Although coating thickness can be controlled to some extent, preparing thicker coatings often faces many problems. For example, as the thickness increases, defects such as cracks caused by drying shrinkage will become more severe. In addition, the solvent evaporation inside thicker coatings is more difficult to completely evaporate, which can easily leave residue and affect the quality of the coating. Therefore, it is generally difficult to prepare thick and qualified high-temperature resistant coatings using this method.
Poor mechanical performance
The hardness, toughness and other mechanical properties of the coating prepared by the sol-gel method are generally inferior to those of some coatings prepared by thermal spraying and other processes, which are mainly composed of metals or ceramics. Under the circumstances of external impact, friction and other conditions, the coating is more likely to be damaged, thus affecting its long-term stable use under some high-temperature conditions with high requirements for the mechanical properties of the coating.

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