Pulse-reverse electrodeposition of a conversion coating based on zinc cation and 3-nitrobenzoic acid on carbon steel to enhance adhesion and protective function of epoxy coating

This work introduces a pulse-reverse electrodeposition method for the application of conversion coating on carbon steel from 0.1 M 3-nitrobenzoic acid and 0.1 M zinc nitrate bath. The impact of current density changes on the surface morphology, composition, and electrochemical characteristics of conversion coatings was explored by surface analysis methods, contact angle, and electrochemical measurements. Results depicted the highest anti-corrosion performance for the sample treated by 0.045 A/cm2. Afterward, an epoxy coating was fabricated over the treated samples. The effect of conversion coating on the epoxy electrochemical behavior and adhesion properties was studied. According to the findings, the adhesion strength and anticorrosion performance of epoxy coating enhanced after the substrate carbon steel being modified by the conversion coating.