Sodium dodecylbenzene sulfonate film absorbed on magnesium alloy surface: An electrochemical, SKPFM, and molecular dynamics study

Sodium dodecylbenzene sulfonate (SDBS) was used as an environmentally friendly corrosion inhibitor to alleviate the corrosion of magnesium alloys in 3.5 wt% NaCl solution. In this study, the corrosion inhibition impact of the SDBS inhibitor on AZ31 alloy surface was investigated by electrochemical, scanning Kelvin probe force microscopy (SKPFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and molecular dynamics (MD) simulation. Electrochemical results indicated that the maximum inhibition efficiency was 93.9% for 0.008 M SDBS after 72 h of immersion. The adsorption of SDBS on the Mg alloy surface obeyed Langmuir adsorption isotherm. The SKPFM and contact angle results show that a thin hydrophobic SDBS film formed on the Mg alloy surface, which isolated the alloy surface from electrolyte and then inhibited micro-galvanic corrosion. Furthermore, the MD simulation substantiated with the experiments and visualized adsorption behavior of the SDBS inhibitor under long-term immersion condition. The long-term corrosion resistance mechanism of the SDBS film is herein proposed.