Corrosion inhibition of layered double hydroxide coating for Mg alloy in acidic corrosive environments

• Published in: Materials and corrosion 2020-01, Vol.71 (1), p.118-124
• Main Authors: Xie, Zhi‐Hui, Wu, Liang
• Format: Article
• Language: English
• Subjects: Benzene; Charge transfer; coating; Corrosion; Corrosion currents; Corrosion inhibitors; Corrosion resistance; Electrochemical impedance spectroscopy; Electrode polarization; Fourier transforms; Hydroxides; inhibitor; layered double hydroxide; Magnesium base alloys; Mg alloy; Morphology; Photoelectrons; Pictures; Protective coatings; Scanning electron microscopy; Sodium dodecylbenzenesulfonate; Spectrum analysis
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.201910995

Layered double hydroxide (LDH) shows promising prospects in the application of intelligent coatings to prevent metals from corrosion, while it is not available under acidic conditions. This investigation aims to improve the corrosion resistance of LDH coating in an acidic environment. The surface morphology, structure, and composition of the LDH coating were characterized by scanning electron microscopy (SEM), X‐ray diffraction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy, respectively. The corresponding corrosion inhibition was evaluated by electrochemical methods, including electrochemical impedance spectroscopy and Tafel curves. The significant increase in coating resistance and charge transfer resistance and the obvious decrease in corrosion current density demonstrate the remarkable improvement of the MgAl–LDH coating in corrosion inhibition. The optical pictures and SEM images show that the coating is corroded severely when sodium dodecyl benzene sulfonate (SDBS) is not added, while it is protected competently without any signs of corrosion after polarization in HCl solutions containing SDBS, which enables the application of a MgAl–LDH coating under an HCl‐corrosive medium. Addition of corrosion inhibitors in corrosive medium enables application of layered double hydroxide (LDH) coating on Mg alloy under an acidic condition. After strong polarization of the MgAl–LDH coating, corrosion is not observed when the concentration of sodium dodecyl benzene sulfonate (SDBS) in 0.01 M HCl solution is increased to 1 mM, indicating the excellent corrosion inhibition of SDBS to the coating and the adaptability of the present methodology.