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

Abstract

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 temperature (RT) and 600°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°C. Dry sliding wear tests indicated that the coating displayed three times better wear resistance at 600°C than at RT. The combined effects of enhanced mechanical 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°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.