In this study, high velocity-oxy fuel (HVOF) technique was used to deposit Cr3C2-NiCr coating on the Ni-base superalloys for their hot corrosion applications. The coatings were characterised with regard to coating thickness, porosity, microhardness and microstructure. The hot corrosion behaviours of the bare and Cr3C2-NiCr coated superalloys were studied after exposure to molten salt (Na2SO4-60%V2O5) at 900°C under cyclic conditions. Optical microscopy, XRD, SEM/EDAX and EPMA techniques were used to characterise the coatings. The thermogravimetric technique was used to establish kinetics of corrosion. The structure of the as sprayed Cr3C2-NiCr coating mainly consisted of γ-nickel solid solution with very low intensity peaks of Cr7C3 and Cr2O3 phases. Some porosity (less than 1.5%), inclusions, unmelted and semi-melted powder particles were observed in the structure of the coatings. Coating microhardness values were found to be in the range of 850-900 Hv (Vickers hardness). The Cr3C2- NiCr coating was resistant to hot corrosion in the given molten salt environment at 900°C. The hot corrosion resistance imparted by Cr3C2-NiCr coatings may be attributed to the formation of oxides of nickel, chromium, and spinels of nickel and chromium.

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