Effect of Some Pyridine Derivatives on the Corrosion Behavior of Carbon Steel in an Environment Like NACE TM0177

An electrochemical study of corrosion behavior for carbon steel in a solution like NACE TM0177 after adding pyridine derivatives is presented. Weight-loss measurements, as the modification of corrosion potentials toward less negative potentials (in linear polarization) in the presence of pyridine compounds, indicated the inhibition of the corrosion process; however, potentiodynamic polarization curves showed an acceleration of the oxidation process. An analysis of the electrochemical impedance spectroscopy (EIS) spectra by equivalent circuit fitting showed charge-transfer resistances that also indicate an activation of the corrosion process. The absence of a corrosion product film shown by scanning electron microscopy (SEM) confirms the results obtained with the electrochemical techniques used in this work. The effect of the pyridine compounds was observed through the modification on the adsorbing species of the double layer through the time constants obtained in the equivalent circuit analysis.