In situ study of selective manganese oxidation on low-alloyed steel using high-temperature cyclic voltammetry

High-temperature cyclic voltammetry was applied to study the early stage oxide formation on low-alloyed steels with different manganese contents. Experiments were carried out at 560 °C using yttria stabilized zirconia (YSZ) as solid eletrolyte and reduced oxygen partial pressure. The acquired voltammograms show the oxidation and reduction sequence from pure iron to hematite. Redox transitions of Mn oxides appear at more positive potentials compared to their standard electrode potentials as a result of incorporation of Mn ions into the Fe2O3 lattice. According to Raman analysis, Fe2O3 peaks are shifted to lower wavenumbers with increasing Mn content. EDX analysis was performed as supporting analytical technique to verify the Raman results. The manganese oxidation behaviour on low alloyed steels as well as the benefits of HT-CV in the field of high-temperature corrosion were successfully demonstrated. •Redox reaction sequence from Fe to Fe2O3 observed for all four steels.•Manganese oxide peaks are shifted to more positive potentials indicating selective oxidation out of the material.•Raman shifts resulting from increasing Mn content suggest incorporation of ionic Mn species in Fe2O3 lattice.