Effects of Nano SiO₂ on the Corrosion Resistance of Epoxy Resin Coatings on Aluminum Alloys

SiO₂/epoxy resin coatings were prepared by adding nano SiO₂ in epoxy resin coating. The corrosion resistance of SiO₂/epoxy resin coatings was studied by Machu test and electrochemical impedance spectroscopy (EIS). The porosity of the coatings was obtained by analyzing the EIS. The results show that the pure epoxy resin coating added with 0%SiO₂ had the worst corrosion resistance, while the epoxy resin coating added with 10% SiO₂ had the best corrosion resistance. The SiO₂ acted as a barrier shield in epoxy resin coatings, but agglomeration occurred in the epoxy resin coating added with too much SiO₂, which decreased the corrosion resistane of the coating. The larger the porosity of coating, the more the micropores and the larger the micropore areas in the coatings, resulting in more transmission channels for corrosive medium and bad corrosion resistance of SiO₂/epoxy resin coatings.