Self-healing polymer coating with efficient delivery for alginates and calcium nitrite to provide corrosion protection for carbon steel

This study described the development of a polymer coating that binds alginates and multivalent cations. This coating utilized cellulose nanofibers (CNF) of 1% to create pathways for the corrosion inhibitors sodium alginate (Alg) and calcium nitrite (CN). These pathways allowed the release of Alg and CN to damaged areas for corrosion protection. Electrochemical impedance of scratches to the coatings was monitored in corrosive solutions to evaluate the self-healing properties of the polymer coatings. The positions of the Alg and CN layers in the coatings were instrumental in the effectiveness of corrosion protection to the damaged areas. As a result, the CN layer was the first to spread to the damaged area, and the Alg layer followed. The combination formed a coating of 8% CN layer and 5% Alg layer with CNF that delivered excellent self-healing properties. The corrosion inhibitors first formed a thin film via nitride ions, which was followed by a well-adhered thick film composed of alginates and calcium ions.