Corrosion Inhibition of Mild Steel by Electrodeposited Poly(M-Aminophenol) Coating

Abstract

In this study, poly(m-aminophenol) (PMAP) coating was electrochemically synthesized by cyclic voltammetry (CV) on mild steel surface to investigate the effects of its barrier protection within the scope of its electrochemical impedance towards further oxidation of the mild steel substrates. The developed PMAP coating were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). The barrier resistance ability of PMAP coating towards corrosion of mild steel was determined in 0.5 M aqueous sodium chloride solution (NaCl) at various immersion times by the electrochemical impedance spectroscopy (EIS). The barrier properties were interpreted through impedance measurement using Nyquist and Bode plots. Equivalent electrical circuit models derived from the plots were employed to describe the coating barrier behaviour and performance. Data obtained showed that, the oxidation peak of PMAP coating were observed at potential +1.0 V (Ag/AgCl). The micrograph of FESEM indicates the formation of a dense and continous PMAP coatings. In FTIR analyses, the presence of peak around 1082 cm-1 ascribed to C–O–C etheric linkage which supported the formation of electro polymerized PMAP coating on mild steel surface. EIS measurement revealed that, PMAP coatings experienced a significant drop in total impedance values with time followed by the development of an electrochemical reactions on coating/metal interface, which indicates the gradual degradation of the barrier resistance ability of the PMAP coatings.