Electrochemical and Corrosion Protection Performance of New Polymer Composite Coatings on Carbon Steel in Sulfuric Acid Medium

Abstract

In this study, galvanostatic electrodeposition mode was used for the synthesis of new composite (Ppy-AOT/PNEA and PNEA/ Ppy-AOT) coatings onto carbon steel of type OLC 45 for corrosion protection. Monolayer poly (N- ethylaniline) (PNEA), polypyrrole (Ppy), dioctyl sulfosuccinate sodium (AOT) and bilayer PNEA/Ppy-AOT and Ppy-AOT/PNEA coatings have been electropolymerization onto carbon steel by galvanostatic synthesis techniques from aqueous solutions 0.1 M N ethylaniline, 0.1M pyrrole, 0.01 M dioctyl sulfosuccinate sodium (AOT) and 0.3 M oxalic acid. In order to include dioctyl sulfosuccinate ions as dopant in the polypyrrole, AOT was also added to the polymerization solution of polypyrrole. The monolayer and bilayer polymers coatings were characterized electrochemically, spectroscopically and morphologically by cyclic voltammetry, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) techniques. Corros ion behaviour of PNEA-AOT/PPY coated carbon steel of type OLC 45 was investigated by potentiostatic and potentiodynamic polarization, open circuit potential measurements and electrochemical impedance spectroscopy (EIS) techniques in 0.5M and 1 M H2SO4solutions. The results of the corrosion tests showed that PNEA/PPY-AOT coatings ensure good corrosion protection of carbon steel in aggressive media. Bilayer coatings revealed better corrosion protection efficiencies than monolayer coatings. The new complex nanostructured composite obtained from this process is promising and might lead to industrial applications in the protection of the carbon steel substrates against corrosion. Keywords: nanocomposite films, galvanostatic electrodeposition, corrosion protection, SEM, EIS, FT-IR