Inhibition of Mild Steel Corrosion using Chitosan–Polyvinyl Alcohol Nanocomposite Films by Sol–Gel Method: An Environmentally Friendly Approach

Abstract

Coatings tailored to corrosion protection of metallic substrates are of the utmost relevance to ensure reliability and long-term performance of coated parts as well as the product value of the coated materials. Presently, there is a strong emphasis on the development of advanced functional and smart coatings for corrosion protection in different technological applications. This work aimed to develop a novel coating based on chitosan and PVA to evaluate its corrosion inhibition effect on mild steel. Chitosan/PVA films were coated on mild steel by dip coating technique. Sol–gel protective coatings have shown excellent chemical stability, oxidation control and enhanced corrosion resistance for metal substrates. Further, the sol–gel method is an environmentally friendly technique of surface protection which has traditionally been used for increasing corrosion resistance of metals. Films so formed were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), the thermal property of the chitosan–PVA film was examined by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Corrosion protection behavior of these coated mild steel substrates in 0.1 N HCl solutions was evaluated by potentiodynamic polarization studies (Tafel), linear polarization studies (LPR), and electrochemical impedance spectroscopy studies (EIS). The experimental results showed that the chitosan/PVA composite coatings were superior to pure chitosan in corrosion protection. EIS measurements and Tafel polarization method have proven that corrosion resistance of mild steel in 0.1 N HCl solutions, increases with increasing the number of layers of chitosan/PVA films. The results indicated that the polymer film adhered to the mild steel surface and inhibited the mild steel corrosion in 0.1 N HCl.