Oxide layer with excellent corrosion resistance obtained on carbon steel by pressure swing oxidation

Utilizing the oxide layer of carbon steel as an anti-corrosion protective layer is an environmentally friendly and cost-effective strategy. In this paper, a novel pressure swing oxidation (PSO) method was used to fabricate an oxide layer on the surface of Q235B, and the limiting effect of PSO on oxidation was presented using a reactive force field (ReaxFF). The surface characteristics and corrosion resistance of the oxide layers formed at varying temperature, as well as the different stage of PSO were investigated, and the formation mechanism of the oxide layer was discussed in detail. It can be found that the PSO process intensively affects the thickness, morphology and surface roughness along with phase composition of the oxide layers, which further influences the corrosion resistance. After the oxidation treatment, the corrosion current density of the treated sample was 3.31 × 10⁻⁷ A·cm⁻² which was reduced by about one order of magnitude in comparison with untreated Q235B. At the same time, an ultra-long passivation zone appeared in the corresponding polarization curve. Moreover, the impedance modulus at 0.01 Hz reached 1.29 × 10⁶ Ω·cm².