STUDY ON THE EVOLUTION OF IMPEDANCE MODEL OF CARBON STEELS COATED BY NANO-SiO2 MODIFIED EPOXY PAINT

摘要

In this paper, the evolution of the impedance model of nano-silicon dioxide modified epoxy coated carbon steels immersed in 3.5% (wt.%) sodium chloride solution was studied using electrochemical impedance spectroscopy (EIS). It is suggested by equivalent electrical circuit fitting results that there was only one capacitive semicircle in the impedance spectra in the initial immersion time, which means there was one time constant. However, with the increasing immersion time, different EIS spectra are showed. So, the impedance model is changed. By the study on the evolution of impedance model in the given system, it can be seen that, the nano-silicon dioxide particles play an important part during the electrolyte diffusing to the surface of the carbon steel and the electrolyte reacting with the carbon steel.