Sulfidation behavior of a ferritic commercial alloy in different sulfidizing environments at high temperature

The sulfidizing behavior of Fe–22Cr–4Al–0.15Zr (wt.%) was studied in two atmospheres: S₂ vapor over the range 4.4–25.4 Pa and H₂–H₂S mixtures corresponding to aP _{S 2} range 0.2–1.297 Pa in the temperature range 973–1373 K. It was found that the constitution of the gaseous phase is of great importance on the corrosion kinetics and the morphology of the corrosion products. Furthermore, a stratification phenomenon during scale growth was observed during the initial sulfidation stage in H₂–H₂S mixtures containing a sufficiently high H₂S partial pressure. This behavior was not observed during tests in puresulfur vapor.