Abstract
Several Fe–Cr-oxide films containing 10, 20, 50 or 90
wt% of Cr
2O
3 were r.f. sputter deposited. These films were made to study the basic corrosion mechanisms of iron chromium alloys and especially the role of the chromium in enhancing the passivity of these alloys. The films were characterised using scanning electron microscopy (SEM), analytical transmission electron microscopy (AEM) equipped with a parallel energy-loss spectrometer (PEELS) and energy-dispersive X-ray spectrometer (EDS), Atomic Force Microscope (AFM), X-ray diffraction method (XRD) and X-ray absorption near edge spectroscopy (XANES). All mixed oxide films showed an amorphous tructure and were composed of hematite,
α-Fe
2O
3, and Cr
2O
3 or a solid solution (Fe,
Cr)
2O
3 between the two oxides. In (Fe,
Cr)
2O
3, iron was in the Fe
3+ oxidation state whereas chromium was found to exist both in the Cr
3+ and in the Cr
6+ oxidation states.