Corrosion Behavior of an HVOF-Sprayed Fe₃Al Coating in a High-Temperature Oxidizing/Sulfidizing Environment

An iron aluminide (Fe₃Al) intermetallic coating was deposited onto F22 (2.25Cr-1Mo) steel substrate using a JP-5000 high velocity oxy-fuel (HVOF) thermal spray system. The as-sprayed coating was characterized by electron microscopy, X-ray diffraction, oxidation, and adhesion. Fe₃Al coated steel specimens were exposed to a mixed oxidizing/sulfidizing environment of N₂-10%CO-5%CO₂-2%H₂O-0.12%H₂S (by volume) at 500, 600, 700, and 800°C for approximately seven days. All specimens gained mass after exposure, inversely proportional to temperature increases. Representative cross-sectioned specimens from each temperature underwent scanning electron microscopy (SEM) and X-ray mapping examination. Results are presented in terms of corrosion weight gain and product formation. The research evaluated the effectiveness of an HVOF-sprayed Fe₃Al coating in protecting a steel substrate exposed to a fossil energy environment.