The passivation of low carbon steel was studied in aqueous solutions of 0.5 M Na2SO4 (pH = 3.5 and 6.5) and of 0.5 M Na2SO4 + 0.001 M NaHSO3 (pH 3.5 and 6.5). The used conversion electron Mössbauer spectroscopy (CEMS) with the complementary electrochemical, microscopic and spectrophotometric investigations proved that the presence of sulfite ion induces pitting corrosion. The compositions and thichnesses of the passive films formed during the electrochemical treatments are determined from the conversion electron Mössbauer spectra. γ-FeOOH was found in each case as a major component. At pH = 3.5, the sextet belonging to Fe3C appears in the spectra in most cases, and also FeSO4 · H2O and could be detected after the shortest (90 min) polarization time.
- acid rain.
- conversion electron Kössbauer spectroscopy
- pitting corrosion
ASJC Scopus subject areas
- Chemical Engineering(all)