High-temperature sulfur corrosion behavior of h-BN-based ceramic coating prepared by slurry method.

The heating surface of a coal-fired boiler is susceptible to high-temperature sulfur corrosion. To investigate and address this problem, a h-BN-based ceramic coating was prepared on the surface of a 20CrMn steel sheet using the slurry method. After sintering, the coating had a relatively dense surface with only a small number of microcracks. The coating and the substrate exhibited a metallic damascene structure and were well bonded. The high-temperature-corrosion behavior of the uncoated and ceramic-coated steel sheets in sulfur dioxide (SO 2 ), hydrogen sulfide (H 2 S), and sulfate environments was investigated. The results show that the coating could effectively prevent inward diffusion of sulfur, and it exhibited high-temperature-corrosion resistance. The high-temperature-corrosion resistance of the coated steel sheet was 8, 7, and 1.7 times that of the uncoated steel sheet in the SO 2 , H 2 S, and sulfate environments, respectively. After corrosion in the SO 2 and H 2 S atmospheres, potassium sulfate (K 2 SO 4 ) crystal grains were formed on the surface of the coating. However, because the coating was relatively dense, thus preventing S diffusion, the presence of K 2 SO 4 was not detected inside the coating. [ABSTRACT FROM AUTHOR]