High-temperature corrosion of aluminized-AISI 1020 steel with NaCl and Na2SO4 deposits

High-temperature corrosion of aluminized-American Iron and Steel Institute (AISI) 1020 steel with sodium chloride (NaCl) and sodium sulphate ( Na 2 SO 4 ) deposits was studied using isothermal oxidization in a dry air environment at 700 ∘ C for 49 h. NaCl and Na 2 SO 4 deposits on the aluminide layer interfered with protective alumina/aluminium oxide ( Al 2 O 3 ) scale formation on the steel substrate. Chlorine and sulphur gases ( Cl 2 g and S g , respectively) released into the atmosphere corroded the protective Al 2 O 3 layer. Corrosion of the Al 2 O 3 layer was also due to local formation of iron oxide ( Fe 2 O 3 ). Fe 2 O 3 growth is attributed to ferric chloride ( FeCl 3 ) vaporization. S g diffusion into the Al 2 O 3 scale via Al 3 + vacancy defects led to the formation of aluminium sulphide on the aluminide layer surface. Cl and S consequently induced hot corrosion of the aluminized steel, thereby increasing cyclic oxychloridation and sulphidation rates at high temperatures.