Chemical state analysis of corrosion products on a steel in H 2S-N 2 and H 2S-O 2-N 2 environment by means of conversion electron Mössbauer spectrometry

Abstract

Chemical states of iron compounds produced on a steel surface, which was exposed to H 2S(0.86 vol%)-N 2(99.14 vol%) environment, were analysed and the variation of iron sulfides formed with the advance of corrosion was experimentally clarified. In the environment, FeS 1− x (mackinawite) was formed as an initial corrosion product and it transformed to Fe 3)S 4 (greigite). Further FeS 1− x , formed at the initial stage of corrosion, was oxidised to γ-FeOOH in the water-saturated air. The production of FeS 1− x was faster in the H 2 S(0.86 vol%)-O 2(20.0 vol%)-N 2(79.14 vol%) environment (relative humidity 100%).