Multiscale Photoelectrochemical Studies on Oxidized Duplex Stainless Steels

Abstract

International audiencePhotoelectrochemical 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 A degrees 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) O-3. 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

CHAPTER 3 Characterisation of Thermal Oxide Scales on Stainless Steels

“…Spatial resolution of the image can be achieved 1 μm by this set-up. High Temperature Corrosion of Stainless Steels: An Alain Galerie Festschrift should be from the higher chromium content in ferritic phase and the faster chromium diffusion rate in ferritic phase [49]. In the austenite phase, iron content is high, inducing higher iron diffusion in the corundum oxide and therefore reducing the chromia fraction [49].…”

“…High Temperature Corrosion of Stainless Steels: An Alain Galerie Festschrift should be from the higher chromium content in ferritic phase and the faster chromium diffusion rate in ferritic phase [49]. In the austenite phase, iron content is high, inducing higher iron diffusion in the corundum oxide and therefore reducing the chromia fraction [49]. In the case of the oxidation in oxygen giving the image shown in Fig.…”