Characterization of Oxide Scales Formed on Ferritic Stainless Steel 441 at 1,100 °C under water vapor
Résumé
This study focuses on the characterization of the oxide scales formed after different exposure times in the range of 2.5-20 min. A commercially available ferritic steel grade AISI 441 was exposed to wet argon at 1100 °C with 5, 9 and 13% H2O. Raman microspectroscopy, XRD, EDS and XPS were used to fully characterize the oxide scale. For all samples exposed for over 4 min, the scale was constituted of three layers in this order: a thin top layer of spinel phases (Fe,Cr,Mn)3O4 with local outgrowths; a second and main layer of Cr2O3 + (Mn,Cr)3O4; and finally a bottom layer of SiO2. The uncommon presence of Fe in the top layer was also observed.