Corrosion Protection Efficacy of the Electrodeposit of Poly (N-Methyl Pyrrole-Tween20/3-Methylthiophene) Coatings on Carbon Steel in Acid Medium

Abstract

In this study, poly(N-methylpyrrole-Tween20/3-methylthiophene) coatings were electrodeposited on carbon steel type OLC 45 by electrochemical techniques in oxalic acid solution. Surfactant Tween 20 as a dopant ion employed during electropolymerization can have an important influence on the corrosion protection of this coating by obstructing the penetration of aggressive sulfate ions. The new composite coatings have been analyzed electrochemically, spectroscopically and morphologically by cyclic voltammetry, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) methods. Corrosion protection consideration of PNMPY-TW20/P3MT-coated OLC 45 has been analyzed by potentiostatic and potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS) measurements in 0.5 M H2SO4 medium. The corrosion rate of PNMPY-TW20/P3MT-coated OLC 45 has been indicated to be ~10 times reduced compared to uncoated OL 45, and the corrosion protection efficiency of the coating is above 90%. The greatest efficacy is achieved by PNMPY-TW20/P3MT composite by electrodeposition at 5 mA/cm2 and 3 mA/cm2 current densities applied and at 1200 mV potential applied in 5:1 and 3:5 molar ratios. The PNMPY-TW20/P3MT coating realized by the galvanostatic method exhibited a non-damaging surveying after 96 h of immersion in the aggressive medium, further verifying its excellent protection capacity. The consequences of the corrosion experiments clearly divulged that PNMPY-TW20/P3MT coatings ensure a very good anticorrosion protection of OLC 45 in aggressive medium.