Active corrosion protection of super-hydrophobic corrosion inhibitor intercalated Mg–Al layered double hydroxide coating on AZ31 magnesium alloy

Abstract

Magnesium alloys, the advanced lightweight structural materials, have been successfully applied in the manufacturing field. Unfortunately, their poor corrosion resistance restrains the potential wide applications. In this work, anti-corrosion coatings were fabricated via the in-situ growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide (Mg–Al LDH) on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating. SEM, XRD, EDS, FTIR, XPS and contact angle test were conducted to analyze physical/chemical features of these coatings. Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings. Surprisingly, Mg–Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance (99.99%) due to the multicomponent synergistic effect such as the physical protection of Mg–Al LDH, the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid. This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field. Keywords: Magnesium alloy, Superhydrophobicity, LDH films, Corrosion inhibitor, Corrosion resistance