Conversion Electron Mössbauer Studies of the Corrosion Products Formed on the Steel Surface in Atmospheres Containing HCl, H2S, and S02

Conversion electron Mossbauer spectrometry, CEMS, was applied to the analyses of the steel surface corroded and the corrosion products formed in HCl, H₂S, and S0₂ environments. In an HCl environment, FeCl₂•2H₂0 and FeCl₂•4H₂0 was formed at the initial stage and transformed into γ-FeOOH if the relative humidity was high and ß-FeOOH if it was low. The exposure to an H₂S atmosphere resulted in the formation of paramagnetic FeS_l-x, as fine particles at the initial stage, coarse ferromagnetic FeS_l-x particles at the intermediate stage, and finally the surface was sulfided to Fe₃S₄. In a combined S0₂ air atmosphere, the formation of FeSO₄•H₂0 and FeS0₄•4H₂0 as the initial and γ-Fe00H as the final corrosion product could be confirmed. The Utility of CEMS for the corrosion study was demonstrated.