Duplex stainless steel passive film electrical properties studied by in situ current sensing atomic force microscopy

• Electrical properties of the passive film on DSS were studied by current sensing atomic force microscopy.
• The conductivity of the passive film on austenite is higher than on ferrite.
• The film conductivity decreases by passivation and drops sharply with the applied potential.
• I–V curves reveal the passive film n- or p-type semiconductor properties.
• XPS analysis demonstrates that the film composition changes with passivation.

The duplex stainless steel passive film electrical properties before and after passivation were investigated by current sensing atomic force microscopy and X-ray photoelectron spectroscopy (XPS). The current maps and band gap energies extracted from I–V curves show that the conductivity of passive film covering austenite and ferrite is different and decreases with increasing film formation potential due to the changes in the passive film thickness and composition, confirmed by XPS analysis. I–V curves reveal that the passive films exhibit p-type or n-type semiconducting properties depending on the film formation potential, attributed to different film chemical composition, supported by XPS results.

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