Simulating study of atmospheric corrosion of steels in a coastal industrial zone: Effect of SO 3 2− on the formation of β-FeOOH rust particles synthesized from FeCl 3 solutions

For simulation of the atmospheric corrosion of steel in a coastal industrial district, β-FeOOH rusts were synthesized by aging the aqueous FeCl3 solutions containing SO32−. The yield and crystallite size of β-FeOOH were remarkably decreased by adding SO32−, implying the suppression of formation and crystallization of β-FeOOH. Before aging, added SO32− broke the coordination of Cl− and OH− to Fe3+ in Fe3+-complexes and reduced the Fe3+ to Fe2+. These facts suppose that SO32− generated by dissolution of SOX gas in thin film water on the steels at a coastal industrial zone markedly inhibits the formation of β-FeOOH rust.