Enhanced Corrosion Resistance of OL 37 Steel in Hydrochloric Acid Using a Novel Composite Polymer Film

This study investigated the electrochemical deposition of a novel composite polymer, 3-methylpyrrole-sodium dioctyl sulfosuccinate/3-methylthiophene (P3MPY-AOT/P3MTP), as protective coatings on OL 37 steel for anticorrosion applications. The anionic surfactant sodium dioctyl sulfosuccinate used in the deposition process enhances the protective efficiency of the coating. The coating films were characterized by CV (cyclic voltammetry), FT-IR (Fourier-transform infrared spectroscopy), and SEM (scanning electron microscopy). The anticorrosive properties of OL 37 steel coated with P3MPY-AOT/P3MTP were investigated in 1 M HCl using potentiostatic and potentiodynamic polarization, as well as electrochemical impedance spectroscopy (EIS). The coated samples exhibited a corrosion rate nearly ninefold lower than the bare substrate, with protection efficiencies exceeding 90%. Optimal performance was obtained for electrochemical deposition of P3MPY-AOT/P3MTP at potentials of 1.0, 1.2, and 1.4 V, current densities of 3 and 5 mA/cm², and a molar ratio of 5:3 for 20 min. The influence of electrochemical polymerization parameters-including applied potential, current density, scan rate, cycle number, and monomer ratio-on the anticorrosion efficiency of the coatings was systematically evaluated, allowing the identification of optimal synthesis conditions. Overall, the results confirm that P3MPY-AOT/P3MTP coatings provide highly effective corrosion protection for OL 37 steel in acidic environments.