Corrosion resistant coating fabrication through synergies between SiOC conversion and iron oxidation at high temperatures

Abstract High-temperature organic coatings protect assets well at moderately elevated temperatures. However, they degrade severely at higher temperatures (e.g., above 450 °C), leaving little or no corrosion protection to the substrate. Here we report a new approach to making high-temperature hybrid coatings through an open-to-air on-substrate thermal treatment that converts an ambient-cured polysiloxane film to a SiOC glassy ceramic film. During the treatment, iron oxidation products synergistically participate in forming the final coherent and adherent film. Characterization of the hybrid coating, especially its chemical composition evolution, reveals that the organic-inorganic conversion goes through three stages. Together with the plasticizing glass fillers, the SiOC conversion and substrate oxidation process resulted in a defect-free corrosion-resistant SiOC barrier film that maintains corrosion resistance even after being subjected to heat treatment at 760 °C for 1 h. This new approach expands SiOC coatings’ applications in extreme environments previously limited by their complex fabrication process.