Fe-based amorphous coating for high-temperature wear, marine and low pH environments

Fe-based amorphous coatings have been manufactured by the high-velocity oxygen fuel (HVOF) process to explore their applications for high-temperature wear, marine and acidic corrosion environments. The microstructural and mechanical characterization of the coating was performed using XRD, SEM-EDS, micro and nanoindentation techniques. The dry sliding wear performance of the coating was analyzed against an Al2O3 ball at room tem-perature (RT) and 600 degrees C. In addition, the corrosion behaviour of coating was evaluated in filtered seawater and 0.5M H2SO4 solutions. The coating retained the amorphous state. Substantial enhancement in nano and micro -mechanical properties were observed after exposure at 600 degrees C. Dry sliding wear tests indicated that the coating displayed three times better wear resistance at 600 degrees C than at RT. The combined effects of enhanced mechani-cal properties due to nanocrystal precipitation and stimulated splat-to-splat cohesion behaviour and a compact, dense oxide glazed layer improved the overall wear resistance at 600 degrees C. The coating exhibited higher corrosion resistance than 316L stainless steel and other Fe-based amorphous coatings in seawater and acidic solutions. In both environments, the coating demonstrated passivation behaviour derived from a layer composed of a stable Cr-based oxide reinforced with Mo and W-based oxides.