An evaluation of the anticorrosion properties of the spinel nanopigment-filled epoxy composite coatings applied on the steel surface

MnAl2O4 nanopigment was synthesized through co-precipitation method. The composition and morphology of the pigment were investigated by X-ray diffraction and scanning electron microscope. Electrochemical impedance spectroscopy (EIS) and linear polarization techniques were utilized to investigate the corrosion inhibition performance of the pigment. Scanning electron microscope (equipped by energy dispersive spectroscopy) was utilized in order to evaluate the surface morphology and composition of the steel samples exposed to the solutions without and with nano-MnAl2O4 pigment. Solubility of nano-MnAl2O4 pigment in the 3.5 wt% NaCl solution was evaluated by inductively coupled plasma test method. Results obtained from X-ray diffraction analysis revealed that nano-MnAl2O4 pigment was synthesized successfully. Results obtained from inductively coupled plasma and electrochemical measurements showed that nano-MnAl2O4 pigment could significantly reduce the corrosion rate of the steel sample immersed in the 3.5 wt% NaCl solution through releasing inhibitive species. Epoxy nanocomposite coatings containing 3 wt% Al2O3 and MnAl2O4 nanoparticles were produced. The epoxy nanocomposites were applied on the steel surface and then their corrosion protection properties were evaluated by EIS. Results showed that the MnAl2O4 nanopigment filled coating showed higher corrosion resistance than the coating loaded with Al2O3 nanoparticle.