| Corrosion electrochemical behavior of composite coatings system in corrosion media was studied by electrochemical impedance spectroscopy (EIS). (1) Corrosion process of chlorinated rubber top coating(single layer), inorganic zinc-rich primer/chlorinated rubber top coating(double layer) and inorganic zinc-rich primer/epoxy middle paste/chlorinated rubber top coating(tir-layer) in 3．5% NaCl solution was studied. A series of impedance spectra of three coatings system during immersion was measured, and the protective properties were compared by the spectra. The results showed that, protective properties of the double layers was even worse than that of the single-layer, and protective properties of the tri-layers coatings in the three coatings was best; epoxy middle paste has played a very important role for protective properties of the composite coatings. (2) The effect of UV irradiation on the electrochemical behavior of the tri-layers coatings during immersion in 3．5% NaCl solution was studied, and electrochemical parameters of the tri-layers coatings was gained by the spectra. The results showed that,corrosion process of the composite coatings in 3．5% NaCl solution can be described in form of Four equivalent circuits. The Rc of composite coatings decreased linearly at rate of 2．2×107Ω·h-1 and 808Ω·h-1 respectively before and after 120h, otherwise, the Cc of the coating increased as line law. UV irradiation can accelerated the aging of the coatings rather than not affect the electrochemical behavior in the solution. (3) Corrosion electrochemical behavior of composite coatings systems in salt-spray was studied by EIS. The effect of coating thickness on the performance resisting salt-spray for the tri-layers coatings was gained. The results showed that, the compactness of composite coatings systems was greatly improved after the coating thickness increased, but it did not affect the electrochemical behavior in the solution. |
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