Raman Studies of corrosion films grown on Fe and Fe-6Mo in pitting conditions

N. Boucherit, A. Hugot-Le Goff and S. Joiret

Corrosion Science, Vol. 32, No. 5/6, pp. 497-507, 1991

Raman spectroscopy is used to identify the corrosion films grown on iron and iron-molybdenum alloy in presence of cl- or SO42-. Pure iron in pitting corrosion is covered by an inner spinel layer and an outer green rust layer. The Raman spectrum of green rust is given for the first time when molybdenum is present in the alloy the green rust is less crystalline, and a molybdate layer is detected at the metal/film interface. The pitting seems to be associated with the presence of Mo4+ in this inner layer, but in passive conditions the films contains FeMoM4.