Comparison of hot corrosion behaviors of thermally sprayed NiCr and Cr3C2–NiCr coatings exposure to molten vanadium pentoxide and sodium sulfate

NiCr and Cr₃C₂-NiCr coatings were deposited on T91 boiler tube steel by high velocity oxy fuel (HVOF) process to enhance their high-temperature corrosion resistance. Hot corrosion studies were conducted on bare as well as HVOF-coated T91 steel after exposure to a molten salt environment at 600 °C under cyclic conditions. Each cycles consisted of 1 h heating in the silicon carbide tube furnace followed by 20 min cooling in air. The mass gain measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. The coatings and the oxide scale formed on the exposed surface were found to be intact with the substrate steel. Cr₃C₂-NiCr coating has provided a better protection to the substrate T91 steel in the given molten salt environment, as a result of the formation of continuous and protective oxides of chromium, nickel and their spinel.