Characterisation of rf Sputtered Fe-Cr-oxide films

Several Fe-Cr-oxide films containing 10, 20, 50 or 90 wt% of Cr2O3 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, alpha-Fe2O3, and Cr2O3 or a solid solution (Fe, Cr)(2)O-3 between the two oxides. In (Fe, Cr)(2)O-3, iron was in the Fe3+ oxidation state whereas chromium was found to exist both in the Cr3+ and in the Cr6+ oxidation states. (C) 1999 Elsevier Science Ltd. All rights reserved.