Enhanced corrosion resistance of an eco-friendly MXene composite coating with self-healing performance

Abstract

Though various kinds of self-healing composite coatings have been proposed for long-term corrosion protection of metals toward sustainable development, the construction of highly efficient and thin coatings via an eco-friendly and time-saving process still remains a challenge. Herein, by combining MXene with strong impermeability and tannic acid as a green corrosion inhibitor, a calcium myristate/MXene composite coating was designed for Al alloys. The resultant thin composite coating (∼21.59 μm) exhibited high corrosion resistance, with a decreased corrosion current density of 7.028 × 10⁻⁹ A cm⁻² in a 3.5 wt% NaCl solution, as confirmed by electrochemical tests, surpassing the performances of calcium myristate and calcium myristate/MXene coatings without tannic acid. The self-healing capability was evaluated by electrochemical tests and the evolution of surface morphology of the scratched coating. The damaged MXene composite coating presented self-healing behavior, with a high self-healing efficiency of 99.53% after 8 days. The self-healing mechanism was attributed to the release of tannic acid from the damaged areas. In contrast to the complex functionalization and preparation process of organic coatings, the comprehensive advantages of this MXene composite coating outperformed those of previously reported self-healing MXene coatings. This work provides a facile strategy for constructing self-healing MXene coatings and expands the application potential of MXene.