Preparation and anticorrosion properties of polyaniline-SiO2-containing coating on Mg-Li alloy

摘要

Purpose - The purpose of this paper is to synthesise polyaniline-SiO2 (PANI-SiO2) composites and investigate the anticorrosion properties of polyaniline-SiO2-containing coating on Mg-Li alloy. Design/methodology/approach - The PANI-SiO2 composites were prepared by in situ chemical oxidative polymerisation in phosphoric acid medium. The PANI-SiO2 composites were characterised by Fourier transform infrared, X-ray diffraction and scanning electron microscopy techniques. The coating consisted of PANI-SiO2 composites and epoxy resin was formed on Mg-Li alloy. The anticorrosion properties were investigated by open circuit potentials (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation curves. Findings - The results indicated that the PANI-SiO2-containing coating on Mg-Li alloy demonstrated good anticorrosion properties in 3.0 wt% NaCI solution. It has been found that the OCP of PANI-SiO2-containing coating were able to maintain more noble potential values in comparison to pure epoxy coatings in 3.0 wt% NaCI solution. EIS analysis indicated that the resistance of PANl-SiO2-containing coating was more than 10~6 ft cm~2 in 3.0 wt% NaCI solution in immersion process. Furthermore, the corrosion current of PANI-SiO2-containing coating on Mg-Li alloy showed a significant reduction. Originality/value - Previous reports on PANI-SiO2 composites were mostly focused on their conductivity and optical properties and there are few studies so far on their anticorrosion properties as protective coatings for Mg-Li alloy.