Improving the anticorrosive performance of epoxy coatings by embedding various percentages of unmodified and imidazole modified CeO2 nanoparticles

Abstract

The surface of CeO2 nanoparticles was modified with imidazole as an effective corrosion inhibitive pigment via layer by layer method. At first, the surface of nanoparticles was coated by polyaniline via oxidative polymerization. Then, the imidazole layer was formed on polyaniline due to opposite electrostatic charges. The modification of nanoparticles by imidazole was investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), Dynamic light scattering (DLS) and Zeta potential (ZP) and Transmission electron microscopy (TEM). The anticorrosion performance of epoxy coating on mild steel in the presence of different concentrations of unmodified and imidazole modified CeO2 nanoparticles (0.5, 1 and 2 wt%) was evaluated in NaCl 3.5 wt% solution by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The optimum percentage of embedded CeO2 nanoparticles in the epoxy coating (unmodified and imidazole modified) was 0.5 wt% in which the coating has minimum agglomeration and appropriate corrosion resistance. The coating resistance of epoxy/imidazole modified CeO2 nanoparticles 0.5 wt% after 200 h immersion in NaCl 3.5 wt% solution was obtained 1.19 × 107 Ω cm2 which is higher than epoxy/unmodified CeO2 nanoparticles (6.51 × 106 Ω cm2). Also, the water uptake percentage of epoxy containing 0.5 wt% of imidazole modified CeO2 nanoparticles at the end of immersion time was obtained 3.85% which was lower than unmodified CeO2 nanoparticles (4.56%) due to inhibitive features and hydrophobicity of imidazole.