Corrosion Performance of New Composite Coatings Onto Carbon Steel By Electrochemical Methods

Abstract

In this study, cyclic voltammetry, galvanostatic and potentiostatic electrodeposition mode was used for the synthesis of new composite (Ppy-AOT/PNEA) coatings onto carbon steel of type OLC 45 for corrosion protection. monolayer poly (N, ethylaniline) (PNEA), polypyrrole (Ppy), and bilayer PNDMA/ Ppy-AOT and Ppy-SDS/PNDMA coatings have been electropolymerization on carbon steel by cyclic voltammetry, galvanostatic and potentiostatic synthesis techniques from aqueous solutions 0.1 M N, ethylaniline, 0.1M pyrrole, 0.01 M dioctyl sulfosuccinate sodium (AOT) and 0.1 M, 0.3 M and 0.5M oxalic acid. In order to include dioctyl sulfosuccinateions as dopant in the polypyrrole, AOT was also added to the polymerization solution of polypyrrole. Characterization of monolayer and bilayer polymer coatings was carried out by cyclic voltammetry, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) techniques. Corrosion behaviour of PNEA-AOT/PPY coated carbon steel of type OLC 45 was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in 1 M H2SO4 and 1M HCl solutions. The results of the corrosion tests showed that PNEA/PPY-AOT coatings ensure good corrosion protection of carbon steel OLC 45 in aggressive media. Bilayer coatings revealed better corrosion protection efficiencies than monolayer coatings. The new nanocomposite realized by this method is promising and might lead to industrial applications in the protection of the carbon steel substrates against corrosion The corrosion protection efficiency follows the order: OLC 45/PNEA/PPY-AOT > OLC 45/PPY-AOT/PNEA > OLC 45/PPY- AOT > OLC 45/PNEA because the presence of these coatings causes a significant decrease in corrosion rate. Keywords: nanocomposite films, electrochemical electrodeposition method, corrosion protection, SEM, EIS, FT-IR