Fabrication and characterization of a Fe3O4/polyvinylpyrrolidone (Fe3O4/PVP) nanocomposite as a coating for carbon steel in saline media

Abstract

Corrosion of carbon steel (CS) is a security and financial concern for numerous industries involving oil, petroleum, and automotive industries. The outstanding mechanical properties and comparatively low price of CS have made it one of the most commonly used materials in many industries. Nevertheless, CS is very vulnerable to corrosion through many applications and media where the iron content of the alloy suffers from oxidation in saline or acidic media. Protection of these alloys against corrosion is an essential strategy to reduce damage and costs of industrial operations. Corrosion protection by polyvinylpyrrolidone (PVP) coating composed of several magnetite (Fe₃O₄) nanoparticle contents was investigated in this research. Primarily, a Fe₃O₄/PVP nanocomposite was prepared and then it was examined by multiple characterization techniques such as FT-IR, XRD, and SEM. CS samples were coated by using the as-prepared nanocomposite through an immersion method. The coating function was evaluated by several electrochemical methods such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, in NaCl 3.5% media. Electrochemical tests results showed that the nanocomposite coating decreased the corrosion current density from 10.56 μA to less than 0.42 μA. Electrochemical impedance spectroscopy data analysis revealed that the charge transfer resistance for the corrosion reaction was increased from 94 Ω for the bare sample up to 159 Ω for the coated sample. The inhibition efficiency of the Fe₃O₄/PVP nanocomposite was found to be ca. 96%. Therefore, the Fe₃O₄/PVP nanocomposite coating can be used as an efficient corrosion protection method for CS.