The electronic structure characterization of oxide film on bulk nanocrystalline 304 stainless teel in hydrochloric acid solution

The electronic structures and compositions of the two oxide films on bulk nanocrystalline 304 stainless steel (BN-SS304) and its conventional polycrystalline counterpart (CP-SS304) after 30 days' immersion test in 0.5 mol/L HCl solution at room temperature were studied by X-ray photoelectron spectroscopy. The enhanced uniform and pitting corrosion resistances of BN-SS304 were attributed to the larger resistance and better chemical stability of the oxide film on BN-SS304, the less corrosion rate of Cr0 for BN-SS304 and the larger atomic percentage of Cr3+ in the oxide film on BN-SS304. The larger resistance of oxide film on BN-SS304 resulted from the less state densities of valence electrons around Fermi level in the oxide film on BN-SS304. The better chemical stability of oxide film on BN-SS304 was attributed to (1) the larger binding energies of Fe2+ 2p3/2, Fe3+ 2p3/2 and Cr3+ 2p3/2 in the oxide film on BN-SS304; (2) the larger atomic percentages of Cr3+ and Fe2+ in the oxide film on BN-SS304.