Corrosion of iron–aluminium alloys in gaseous atmosphere containing hydrogen chloride and hydrogen sulphide at 600 and 700°C

AbstractThe corrosion of two binary iron–aluminium alloys was compared in gaseous CO2–H2–HCl–H2S and CO2–H2 mixtures at 600 and 700°C. In each environment, the Fe–14Al alloy resisted corrosion due to the formation of a protective alumina scale. The Fe–4Al alloy corroded more rapidly in the CO2–H2–HCl–H2S atmosphere than in the CO2–H2 atmosphere at both temperatures. The corrosion products comprised thick outer layers of iron oxide, porous inner layers of mixed iron–aluminium oxide and internal precipitates of aluminium oxide. Sulphur was detected near the scale/alloy interface and the increase in corrosion rate was attributed to the presence of chlorine and sulphur.