Self-Healing of Layered Double Hydroxide Film by Dissolution/Recrystallization for Corrosion Protection of Aluminum

Abstract

The development of smart corrosion protection systems for aluminum and aluminum alloys is a subject of prime importance. Self-healing materials with longer lifetime and lower production costs have received extensive attention. Herein we report an intrinsic self-healing coating of in situ-grown inorganic zinc, aluminum-containing layered double hydroxide (ZnAl-LDH) film with improved corrosion-resistant performance in chloride-containing solution. An artificial defect roughly 30 μm in width, which penetrated to the aluminum substrate, was made by a razor blade to show the process of self-healing. After immersion in the solution of 3.5 wt% NaCl for a period of time, new LDH crystallites on the aluminum substrate at the site of the artificial defect were observed by scanning electron microscope (SEM). Electrochemical impedance spectroscopy (EIS) and dc polarization curves were monitored in artificial seawater at room temperature to further demonstrate the self-healing process. A possible dissolution/recrystallization mechanism was proposed and confirmed to illustrate the phenomenon of self-healing. The ZnAl-LDH film with self-healing ability can reduce the corrosion of aluminum dramatically. Also, the concept of self-healing via dissolution/recrystallization was extended to improve the corrosion resistance of aluminum alloy.