Multiscale Photoelectrochemical Studies on Oxidized Duplex Stainless Steels
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Photoelectrochemical characterizations at macroscopic, microscopic and mesoscopic scales were performed on thermally oxidized duplex stainless steel samples, with special attention paid to the differences exhibited by the oxides formed on austenitic and ferritic grains. Whereas duplex stainless steel oxidized in water vapour exhibited overall n-type semiconduction after 5 min oxidation, or n-type semiconduction combined with an insulating behaviour after 1 h oxidation at 850 °C, only overall p-type semiconduction was shown by samples oxidized in oxygen. Mesoscopic experiments allowed to put in evidence that the oxides grown on austenitic grains showed a lower chromium content in Fe2−x Cr x O3. On the other hand, the contrast in the photoelectrochemical images could be explained by the ratio of the photocurrents measured on austenitic grains to the ones measured on ferritic grains. Atmosphere-dependent changes in the relative chromia fraction in austenitic and ferritic grains were also evidenced.
KeywordsPhotoelectrochemistry Oxidized duplex stainless steel Multiscale analysis
The authors wish to gratefully acknowledge APERAM STAINLESS FRANCE (Centre de Recherches d’Isbergues) for providing 2205 duplex stainless steel. One of the authors (A.S.) would like to thank to Ministry of Sciences and Technology, Thai Government, for the PhD scholarship.
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