Superhydrophobicity and high corrosion resistance of secondary alkane sulphonate (SAS) modified Li-Al LDH film in-situ grown on aluminum alloy

Abstract

In this work, a secondary alkane sulfonate (SAS) modified Li-Al LDH film (SLDH) with high corrosion resistance by a simple in-situ growth on aluminium alloy 6N01. Water contact angle (WCA) and scanning electron microscopy (SEM) revealed that the film was fabricated with a flower-shaped microstructure and highly superhydrophobic performance (WCA=153°). XRD patterns and FTIR spectrum revealed that SAS species were intercalated into SLDH. X-ray photoelectron spectroscopy (XPS) analysis indicated that SLDH was mainly composed of C, O, S, Al and Li. Potentiodynamic polarization (PDP) curves proved that SLDH (i_corr = 9.169 × 10⁻⁸ A/cm²) provided pronounced protection than that of CLDH (i_corr = 9.011 × 10⁻⁷ A/cm²), and electrochemical impedance spectra (EIS) demonstrated that corrosion resistance was improved. Neutral salt spray (NSS) tests exhibited that compared to CLDH with severe pitting corrosion, SLDH was virtually undamaged after 360 h exposure. Based on the above results, a sound inhibition mechanism of SLDH was inferred to be a dual effect, including the barrier action of superhydrophobic surface and the ion exchange of intercalated SAS with aggressive chlorides. In conclusion, the special divergent long-chain structure of SAS with low surface energy results in the superhydrophobicity of SLDH.