Improving the anticorrosive performance of epoxy coatings

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).

Different concentrations of nanoparticles

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.

Varying coating 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.

The study is published in: Progress in Organic Coatings Volume 122, September 2018, Pages 56-63.