Study of the corrosion layer on iron obtained in solutions of water-polyethylene glycol (PEG 400)-sodium phosphate

The iron behaviour in phosphate/water/polyethylene glycol (PEG) was studied in-situ and ex-situ by spectrometry Raman, ESCA spectroscopy, X-ray diffraction, Auger spectroscopy were used as surface analysis methods. It changes with phosphate concentration. At low phosphate concentration (5 x 10(-4) M-10(-3) M-5 x 10(-3) M), iron is corroded. The thin corrosion layer is a mixture of iron oxides (gamma-Fe2O3, Fe3O4) and iron phosphate( Fe-3(PO4)(2), 8H(2)O). At high phosphate concentration (10(-2) M-5 x 10(-2) M), the iron is protected. The protection could be due to an heterogenous layer containing PEG 400 and phosphates. (C) 2003 Kluwer Academic Publishers.