Anticorrosive and photocatalytic properties research of epoxy-silica organic–inorganic coating

Abstract

The organic-inorganic hybrid coating was fabricated for anti-corrosion application using bisphenol A diglycidyl ether (BADGE) epoxy resin with inorganic silica nanoparticles prepared by sol-gel method. The precursor, tetraethyl orthosilicate (TEOS) formed via hydrolytic condensation the silica dispersed in the protective coating on the metal substrate that could prevent the permeation of corrosive media. In order to increase the functionality of the coating, the photocatalyst zinc oxide (ZnO) nanoparticles were added to bestow the light degradation on the coating. The as-fabricated nanoparticles and coatings were analyzed using Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis spectrum (UV–vis) analysis. The anti-corrosion performance of the organic-inorganic hybrid coating was investigated by electrochemical impedance spectroscopy (EIS) and salt spray tests. Noteworthily, EIS results showed that the epoxy-silica organic-inorganic coating was109Ωcm2,which could increase the impedance modulus (at 0.01 Hz) of Q215 steel by about 7 orders of magnitude after immersion in 3.5 wt% NaCl aqueous solution for 96 h. The salt spray test results showed that metal substrate was still not completely corroded after 68 days. In addition, the addition of ZnO to the coating has photo-degradation effect on methyl orange and the photo-degradation efficiency can reach 55%.