Raman Spectroscopy and X.P.S. investigations of anodic corrosion films formed on Fe-Mo alloys in alkaline solution

D. Thierry, D. Person, C. Leygraf, N. Boucherit, A. Hugot-Le Goff

Corrosion Science, 32, 1991, 497

Raman spectroscopy and X-ray photo-electron spectroscopy have been used to study anodic films formed on iron-molybdenum (Fe-Mo) alloys. It is shown that the composition of the passive film formed after oxidation/reduction cycles (ORC) in 1M KOH depends upon the anodic reversal potential and the sweep rate of the ORC. Finally it is concluded that the growth of the ferric outer layer (amorphous a-FeOOH able to crystallize in a-FeOOH or g-FeOOH after a certain number of cycles) is related to the reductio of the magnetite (Fe3O4) inner layer that provides a source of iron ions.