Corrosion Resistance of Fe-Cr-Mo-(C,B,P) Amorphous Coatings Thermal Sprayed by HVOF and APS Processes

Two kinds of Fe-16Cr-30Mo-(C,B,P) alloy powders of different composition were thermal sprayed onto mild steel using HVOF and APS processes. Perfect amorphous coating was formed by HVOF and APS processes in both powders. The corrosion potential of the amorphous coatings sprayed by HVOF process was higher and the passive current density was lower than that of the amorphous coatings sprayed by APS process in 1N HCl solution. The coatings of perfect amorphous phase were little corroded after one week immersion tests and the corrosion rates of the amorphous coatings showed a fairly less value of 0.03 mm/y compared with Inconel 625 plate in 5N HCl solution at room temperature.