RESUMEN
In this work, polypyrrole-based nanocomposites doped with graphene oxide, molybdate, and salicylate (PPy/GO/Mo/Sal) were synthesized via in situ electrochemical polymerization to enhance the anti-corrosion protection performance of polymer coatings. The morphology and structures of the coatings were characterized by SEM, EDX, FTIR, Raman spectroscopy, and XRD. The protection abilities of coatings against corrosion were investigated in 0.1 M NaCl solution with EIS potentiodynamic polarization, salt spray test, and open-circuit potential (OCP) measurements. The results showed that with the presence of both molybdate/salicylate and GO in the PPy matrix, the nanocomposite coating exhibited an excellent protection ability against corrosion for low-carbon steel, better than that with only GO as filler. Compared to the nanocomposites doped with only salicylate or salicylate/GO, the one doped with both molybdate/salicylate and GO exhibited the longest protection plateau (ca. 100 h) on the OCP-time curves with some fluctuation points known as the self-healing action of molybdate dopant. It also resulted in a decrease in the corrosion current (Tafel plots), a higher impedance (Bode plot), and a better protection performance in salt spray tests. In this case, the anti-corrosion ability of the coatings was provided through a barrier and self-healing mechanism.
RESUMEN
Polypyrrole (PPy) films doped with molybdate and salicylate have been successfully electropolymerized on low carbon steel in aqueous solutions containing both molybdate and salicylate in a one-step process that did not require any pre-treatment of the steel substrate. Salicylate-doped PPy films were synthesized in the same way for comparison. The steel surface was rapidly inhibited and the PPy-based films were formed on it easily. The PPy-based films were characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray, and thermal gravimetric analysis methods. The corrosion protection performance of the coatings was investigated with electrochemical impedance spectroscopy, open circuit potential (OCP), salt spray test, and Tafel polarization. It was found that in the presence of both molybdate and salicylate as dopants, the films on steel could present a better corrosion resistance than PPy film doped with only salicylate. The self-healing property of PPy-based films was observed on the OCP measurement with the fluctuation of rest potential. The salt spray test results showed that the PPy film doped with both salicylate and molybdate was more salt-resistant than the PPy film doped with only salicylate. The results suggest that the PPy coatings doped with both molybdate and salicylate are potential for application as metallic anti-corrosion coatings.
