The isothermal high temperature corrosion behavior of an FeAl coating, coated on 9Cr1Mo steel through laser surface alloying, was studied in atmospheres of pure oxygen and O2 ? 1 %SO2. The specimens were tested at 500, 600 and 700 C for 4–100 h. The mass change of the specimens versus time of exposure was used to study the kinetics of oxidation. The coating degradation through interdiffusion of alloying elements between the surface layer and substrate was investigated by long-term oxidation tests in air. OM, SEM, FESEM, EDS and EPMA analyses were used to study the oxidation behavior of the intermetallic coating. The results showed excellent oxidation/sulfidation resistance of the coated material due to a negligible growth rate of the oxide scale. However, the coating was degraded because of the interdiffusion of Al and Fe atoms between the coating and substrate after prolonged exposure to elevated temperatures.
