Cr3C2-NiCr, NiCr, WC-Co and Stellite-6 alloy coatings were sprayed on ASTM SA213-T11 steel using the HVOF process. Liquid petroleum gas (LPG) was used as the fuel gas. Hot corrosion studies were conducted on the uncoated as well as HVOF sprayed specimens after exposure to molten salt at 9000C under cyclic conditions. The thermo-gravimetric technique was used to establish the kinetics of corrosion. XRD, SEM/EDAX and EPMA techniques were used to analyse the corrosion products. All these overlay coatings showed a better resistance to hot corrosion as compared to that of uncoated steel. NiCr Coating was found to be most protective followed by the Cr3C2-NiCr coating. WC-Co coating was least effective to protect the substrate steel. It is concluded that the formation of Cr2O3, NiO, NiCr2O4, and CoO in the coatings may contribute to the development of a better hot corrosion resistance. The uncoated steel suffered corrosion in the form of intense spalling and peeling of the scale, which may be due to the formation of unprotective Fe2O3 oxide scale.

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