Corrosion Behavior of Epoxy/Polysulfide Coatings Incorporated with Nano-CeO2 Particles on Low Carbon Steel Substrate

Abstract

The corrosion resistance properties of epoxy coatings applied to St37 carbon steel were modified with polysulfide and nano cerium oxide (CeO2). The surface chemistry of the epoxy/polysulfide coating was studied by Fourier transform infrared spectroscopy, which confirmed the presence of the thiol group. The toughness and corrosion properties of epoxy/polysulfide composites were investigated by cupping and electrochemical impedance spectroscopy (EIS) tests, respectively. Results showed that the addition of 10 wt% of polysulfide to epoxy, led to a notable increase in toughness and corrosion resistance. Epoxy/polysulfide/CeO2 nanocomposites were prepared by incorporating 0.5 wt%, 1 wt%, 2 wt%, 4 wt%, and 6 wt% of CeO2 nanoparticles into the epoxy coating with 10 wt% of polysulfide. Field emission scanning electron microscopy observations indicated the uniform dispersion of 1 wt% nano CeO2 and agglomeration of higher concentrations of particles in the composite. The effect of nano CeO2 on the corrosion behavior of the coatings was investigated in a 3.5% NaCl solution using EIS and salt spray tests. The adhesion strength of the nanocomposites was measured by a pull-off adhesion tester. Results revealed that the incorporation of 1 wt% CeO2 nanoparticles significantly increased the corrosion resistance and adhesion strength of the epoxy/polysulfide coatings.