Effects of various fillers on the thermal shock and fouling resistance characteristics of zirconia-based composite coatings for high-temperature applications

Composite coating technology has been extensively developed to meet industrial demands for coatings with specifications that exceed the capabilities of conventional coating technologies and that can function in extreme environments and high temperatures. The composite coating in this study is focused on materials that have hydrophobicity. To achieve this hydrophobicity, the coating must have at least one restrictive property: antifouling. In this research, antifouling coating materials based on certain zirconia ceramic composites (ZrO2) and fillers, such as boron nitride, MoS2, and graphite, are chosen. The substrate used is a low-carbon steel, which is used in high-temperature power plants. The slurry spray coating method is chosen, which is a simple and low-cost method. Thermal shock and fouling resistance tests are conducted, and the samples are further observed with Scanning Electron Microscopy-Energy-Dispersive X-ray Spectroscopy (SEM-EDS). The results show that the higher the hBN filler content in the zirconia composite coating is, the better the thermal shock and antifouling resistance levels. This phenomenon is indicated by the lower delamination of the coating after the thermal shock treatment and the lower fouling of sodium sulfate deposits on the surface of the coating after the antifouling treatment than before. The same result is shown by the zirconia composite coating with hybrid filler (hBN-MoS2-Graphite).