High Temperature Corrosion Performance of Carbon Steel Coated with Iron Aluminide in Mixture of O2 and SO2 Atmosphere

In this investigation the surface of an aluminized sample of plain carbon steel was melted and alloyed using a tingsten inert gas (TIG) welding process to produce iron-aluminide intermetallic phases on the surface. The produced coating was then characterized by SEM and EDS and its high-temperature properties in O₂ + 1%SO₂ gas were examined. The results showed that the Fe₃ Al coating produced could protect the substrate as it was subjected to the corroding gases at 700°C due to the formation of an alumina layer between the substrate and an outer layer of Fe₂ O₃ . At 900°C, the coating could only protect the substrate for 64 h. The lack of further protection at this temperature is attributed to the decrease in the protective properties of alumina with an increase in its temperature and the lack of presence of enough Al atoms in the coating for the repair of the defects formed in the alumina layer.