ELECTROCHEMICAL REDUCTION OF THERMALLY PREPARED OXIDES OF IRON AND IRON CHROMIUM-ALLOYS STUDIED BY INSITU RAMAN-SPECTROSCOPY

Pure Fe and Fe/Cr alloys (3% and 12% Cr) were oxidized at 250-260 degree C and subsequently electrochemically reduced in borate buffer, pH 8. 4. The reduction was followed by in situ Raman spectroscopy as well as chronopotentiometric and chronoamperometric measurements. At several time intervals ex situ Raman control investigations and ESCA analyses were undertaken. Although at minus 0. 7 V vs sce partial reduction of the oxide film was observed, alpha -Fe//2O//3 remained unchanged and reduced at minus 0. 9 V. A. mixture of spinel structured oxide, possibly Fe//3O//4, and a ferrous deposit were observed when the oxide film was galvanostatically reduced at 100 mu A cm** minus //2; after prolonged reduction the bare metal resulted.