Preparation and anticorrosion properties of polyaniline-containing coating on Mg-Li alloy.

Purpose – The purpose of this investigation was to synthesize a doped polyaniline-containing coating and investigate the anti-corrosion properties of the coating on Mg-Li alloy. Design/methodology/approach – The doped polyaniline pigments were prepared by two different methods using ammonium persulphate as oxidant and hydrochloric acid, phosphoric acid, p-toluene sulfonic acid and sulfosalicylic acid as doping agents. The doped polyaniline was characterized by Fourier transform infrared (FT-IR) analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The coatings consisted of polyaniline, epoxy resin and other additives that were formed on Mg-Li alloy. The anti-corrosion properties of the polyaniline-containing coating on the Mg-Li alloy were investigated in 3.5 wt.% NaCl solution using open circuit potential logging and electrochemical impedance spectroscopy. Findings – The results of the electrochemical tests indicated that the polyaniline-containing coatings showed better anti-corrosion properties, as compared to conventional epoxy coatings on Mg-Li alloy when exposed in 3.5 wt.% NaCl solution. The coating containing 2 wt.% polyaniline (relative to the mass of epoxy resin) doped with hydrochloric acid had the best anti-corrosion properties on the Mg-Li alloy. Originality/value – Previous reports on the anti-corrosion properties of polyaniline-containing coatings focused mainly on the surface of iron, steel, aluminum and magnesium, and there have been few studies on the anti-corrosion properties as protective coatings for Mg-Li alloy. [ABSTRACT FROM AUTHOR]