Effect of tin on the corrosion behavior of sea-water corrosion-resisting steel

• Tin-containing steel has lower corrosion current and higher impedance than tin-free steel.
• SnO2 and SnO formed in the rust layer increase the corrosion resistance of steel.
• Corrosion products of tin have a coprecipitation process with iron oxides.
• Tin can improve the oxidation resistance of substrate steel.

This paper investigated the effect of tin on the corrosion resistance of tin-containing steel and tin-free steel using electrochemical measurements in seawater. Results showed that tin-containing steel had lower corrosion current and higher impedance than tin-free steel. Surface analyses of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) indicated that tin could form SnO2 and SnO in rust layer, and both of them could improve impedance and corrosion resistance of rust layer. Besides, the coprecipitation process of tin oxides with iron oxides could make the rust layer more uniform and compact, which could make the tin-containing steel have better corrosion resistance than tin-free steel. Secondary ion mass spectrometer (SIMS) showed that there was no obvious segregation of tin on substrate steel when tin addition was 0.038 wt.%, and tin could improve the oxidation resistance of substrate steel evenly by lowering the steel's Fermi energy from − 9.276 eV to − 14.445 eV.

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