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

Abstract

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 × 1011 Ω cm2 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 × 108 Ω cm2 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.