Corrosion Mechanism of Plasma-Sprayed Fe-Based Amorphous Coatings with High Corrosion Resistance

Fe45Cr16Mo16C18B5 amorphous coatings were deposited on the mild steel substrate (0.45 wt.% C) by plasma spraying, and their corrosion resistance in 3.5 wt.% NaCl solution was compared with those of the substrate and 316 stainless steel. Potentiodynamic tests revealed that the as-prepared coatings had higher resistance to local corrosion than 316 stainless steel due to their wide passivation range. Electrochemical impedance spectroscopy (EIS) measurements further explained the long-term corrosion process of the coatings and indicated their excellent corrosion resistance. Based on this analysis, a schematic diagram of the corrosion mechanism of the coatings was proposed. The obtained results imply that Fe45Cr16Mo16C18B5 amorphous coatings have a promising prospect for industrial applications.