LAUSR

Abstract The main aim of the present work is to investigate the high-temperature corrosion behavior of bare, high-velocity oxy-fuel coated on iron-based superalloy A-286. Ni-20%Cr and Cr3C2-25%NiCr powders are deposited on the Fe based superalloy A-286 material by high-velocity oxy-fuel (HVOF) process. Surface roughness and coating thickness of the coated specimen is evaluated using surface roughness tester and optical microscope (OM). The hot corrosion study was performed on bare, and HVOF coated Fe-based superalloy A-286 in Na2SO4-50%V2O5-10%NaCl environment at 700 °C under cyclic conditions. Kinetics of corrosion has been determined by thermo-gravimetric analysis using mass change measurement; Cr3C2-25%NiCr coating shows the better corrosion resistance due to the formation of stable Cr2O3 layer. The uncoated superalloy is severely suffered by spallation and sputtering of oxide scales during hot corrosion study. The surface microstructure, chemical composition and phase identification of coatings before and after hot corrosion are analyzed using scanning electron microscope/ energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis. Depth of corrosion attack and oxide scales are characterized using EDS compositional analysis and elemental mapping technique. The result of the cross-sectional image shows that uncoated material was severely suffered by hot corrosion to a depth of 200 µm.