A smart acid-responsive GO/MS/BTA hybrid epoxy-based anti-corrosion coating for Mg alloy

Conventional surface coatings exhibit poor self-healing ability, especially under the acid corrosion conditions, which is regarded as a huge challenge for the effective protection of Mg alloy . In this study, a smart self-healing hybrid coating is facilely fabricated, providing an excellent long-term anti-corrosion performance for Mg alloys within the harsh environments. Mesoporous silica (MS) loaded with corrosion inhibitor benzotriazole (BTA) is grafted onto the surface of graphene oxide (GO), to synthesize GO-based nanomaterials , which can be uniformly dispersed in the epoxy (EP) coating through ring opening reaction and form the covalent bonds . Electrochemical Impedance Spectroscopy (EIS) results show that the modulus of the EP-GO-MS-BTA hybrid coating remains at 2.57 × 10 11 Ω cm 2 after immersion in 3.5 wt% NaCl solution for 15 days. In contrast to previously reported works that achieved the self-healing ability in acidity, the current EP-GO-MS-BTA coating represents an ultra-high self-healing efficiency of 1.2 × 10 8 Ω cm 2 h −1 under acid 3.5 wt% NaCl condition (pH = 3). Due to the labyrinth effect, the impermeability of epoxy coating is enhanced by the ameliorative dispersity of GO sheet. In addition, the as-prepared GO-based nanomaterial can be used to load corrosion inhibitor BTA and possess H + ion-responsive release property, leading to an improved corrosion protection . Combining the dual effects of superior GO dispersion and smart self-healing, it will provide a green and convenient synthetic method for constructing self-healing coatings with the excellent anticorrosion resistance.