A ceramic coating from polymer-derived SiCNO for high-temperature electrical insulation on Ni-based alloy substrates

High-temperature thin-film sensors on nickel-based alloy high-temperature components are important for design validation and health monitoring of such high-temperature components, however, maintaining good electrical insulation at high temperatures remains a challenge for the stability and reliability of thin-film sensors. In this study, an insulating coating on nickel-based alloy substrate is proposed to solve the electrical insulation problem of thin-film sensors. A layer of precursor ceramic slurry is prepared on a nickel-based alloy substrate by direct-write printing method, and then a layer of pure precursor liquid is spin-coated on it after vacuum pyrolysis, and then a four-layered structural insulating coating is formed by the vacuum pyrolysis at last. The coatings were characterized by SEM, EDS, FTIR, XRD and XPS for surface morphology, elemental content, functional groups, and physical phase composition. The electrical resistance of the coatings was tested at high temperatures and their adhesion at room temperature was tested. Finally, the temperature and thermal shock resistance of the coatings were verified by preparing thin-film thermistors and heat flux sensors on the coating. A high-temperature resistant electrically insulating coating is provided for the preparation of thin-film sensors on high-temperature nickel-based alloys.