Rapid Conversion of Perhydropolysilazane into Thin Silica Coating at Low Temperature

The conversion of perhydropolysilazane (PHPS) to silica at low temperature is beneficial for its application on thermally vulnerable substrates. In this work, it is demonstrated that (3-aminopropyl)triethoxysilane (APTES) has high catalytic efficiency for the low temperature conversion of PHPS and the catalytic mechanism of APTES was suggested. The influence of temperature and humidity on the catalytic conversion process was investigated, and it was found that PHPS can be rapidly converted to silica in 10 min at 80 degrees C with relative humidity of 90%. The achieved silica is mainly composed of SiNO3/SiO3OH and SiO4 structure with O/Si of 1.74 and N content of 1%. As an approach to prepare inorganic coating, the low-temperature conversion method achieves a silica coating with low volume shrinkage of 0.86%, low roughness of R-a=0.293 nm, high nanoindentation hardness of 3.62 GPa and modulus of 30.06 GPa, which exhibits high potentials as protective coating for various materials even those vulnerable to high temperature.

Automated summary

This study demonstrates the high catalytic efficiency of (3-aminopropyl)triethoxysilane (APTES) for the low temperature conversion of perhydropolysilazane (PHPS), and suggests the catalytic mechanism of APTES. The influence of temperature and humidity on the conversion process is investigated, and it is found that PHPS can be rapidly converted to silica at 80 degrees C with 90% relative humidity. The obtained silica coating has low volume shrinkage, low roughness, high nanoindentation hardness, and modulus, showing high potential as a protective coating for various materials, even those vulnerable to high temperature.