Advanced self-healing coatings based on ZnO, TiO2, and ZnO-TiO2/polyvinyl chloride nanocomposite systems for corrosion protection of carbon steel in acidic solutions containing chloride

Abstract

Anti-corrosion protective self-healing coating systems for carbon steel that utilizes ZnO, TiO2, and ZnO-TiO2 nanocomposites and polyvinyl chloride (PVC) as an organic healing agent was introduced. These nanocomposites systems were fabricated by a facile preparation method by the coating of ZnO, TiO2, and ZnO-TiO2 with PVC. These synthesized systems are well characterized by the investigation techniques of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), and Transmission electron microscopy (TEM). The good crystallinity of the zincite and anatase phases was confirmed by XRD studies along with a nano grain size of 46.5 nm for ZnO and 13.5 nm for TiO2. ZnO, TiO2, and/or ZnO-TiO2/polyvinyl chloride composites films were applied as an anti-corrosive coating deposited on carbon steel by dip-coating processes. The anticorrosion performance of uncoated and coated carbon steel was inspected in 0.5 M HCl+3.5% NaCl by performing immersion test, Eocp vs. time, impedance spectroscopy (EIS), and potentio-dynamic polarization (PDP) methods. The ZnO, TiO2, and/or ZnO-TiO2/PVC composite coating exhibited premium protection against corrosion of C-steel with protection capacity of 96.2–97.1% after 10 days of exposure. The capacity of the fabricated films increased in the order of ZnO-TiO2/PVC > TiO2 /PVC > ZnO /PVC. The surface topology of the coated specimen before and after 240 hrs dipping in the aggressive medium was assessed using FE-SEM. The current study contributes to the preparation of novel protective systems with self-healing capability for steel corrosion in acidic medium containing chloride.