nvestigation of Anti-corrosion Properties of Epoxy Coating Containing Clay Nanoparticles Using EIS and Scanning Kelvin Probe

The purpose of this study was to investigate the effect of the Clay nanoparticles on the protective properties of the epoxy coating on carbon steel. The results of the electrochemical impedance spectroscopy (EIS) showed that the addition of this nanoparticle increased the corrosion resistance of the epoxy coating. The resistance of the coating containing 3% nanoclay after 1000 hours immersion in NaCl 3.5 wt. % was about 3.1 × 106 Ω.cm, indicating good resistance to the coating in the corrosive environment. Also, the results of electrochemical impedance showed that coating containing 3% nanoclay showed better resistance than coating containing 5% nanoclay. The results of the Scanning Kelvin Probe (SKP) showed that in nanoclay-containing samples after 2500 hours, the average potential of the surface gradually dropped from -345 mV to -700 mV, and the drop in surface potential in the presence of nanoclay was much less than in presence of nanoclay which indicates the positive effect of these nanoparticles on corrosion control. Moreover, Volta potential of varnish without a nanoparticle, reached a much lower level over the same period than a nanoclay sample of about 1500 mV. Finally, exfoliated nanoclays by reducing and prolonging the penetration path of electrolyte containing oxygen, water, and corrosive ions controlled the corrosion rate and postponed the time of penetration of the electrolyte.