Corrosion behavior of the oxide films modified with zincizing treatment on AISI 1020 steel

Oxide films were formed on AISI 1020 steel in air at 260 °C with/without zincizing treatment. Corrosion behaviors of the oxide films were investigated by electrochemical potentiodynamic polarization, scanning electron microscope (SEM), photocurrent measurement and Mott-Schottky response analysis. Compared with that without zincizing treatment, the polarization curve of the oxide films with zincizing treatment showed a higher breakdown potential, lower corrosion current density and lower passive current density. Meanwhile, the SEM images suggested that the oxide films with zincizing treatment were more compact than that without zincizing treatment. Furthermore, the photoelectrochemical response results indicated that the composition of the oxide films with zincizing treatment was ZnFe2O4, FeOOH and ZnO while the composition of that without zincizing treatment was Fe2O3. By zincizing treatment, the photocurrent response value and the concentration of the carriers was decreased, the flat band potential of the oxide films was moved in the negative direction.