Smart anti-corrosion self-healing zinc metal-based molybdate functionalized-mesoporous-silica (MCM-41) nanocomposite coatings

Abstract

We report on the electrodeposition of smart corrosion-resistant zinc-based composite coatings containing mesoporous silica (MCM-41), impregnated with molybdate. The molybdate functionalization, which is known as a common corrosion inhibitor, was added as an "anti-corrosive self-healing" agent to the coating to be released during the corrosion process. The dispersion and bonding of the functional MCM-41 particles in the electrodeposition solution were both improved by adding 3-mercopropyltrimethoxysilane (MPTMS). Zinc metal base was co-deposited galvanostatically with the MCM-41 particles under conditions that were varied to achieve the smoothest and most corrosion-resistant films. The open circuit potential of Zn-MCM-41-SH-Mo (SH: silane, Mo: molybdate functionalization) in a chloride solution increases as a function of time owing to the release of Mo as an anodic inhibitor which makes the self-healing functionality in the coating. Based on electrochemical impedance spectroscopy and potentiodynamic polarization tests, it was observed that the corrosion resistance increases in the order: Zn-MCM-41-SH-Mo > Zn-MCM-41-Mo > Zn-MCM-41 > Zn.