Nanocontainers-enhanced self-healing Ni coating for corrosion protection of Mg alloy

Self-healing coating based on nanocontainers (NCs) has been emerging as a great strategy to improve the anticorrosion ability of susceptible metal substrate. However, all the research referred to such smart coating to date is focus on organic coating instead of metallic coating. To fill this gap, 2-mercaptobenzothiazole (MBT) loaded porous hollow SiO₂ NCs are synthesized and incorporated successfully into an electroless Ni coating on Mg alloy in this work. The surface morphologies and the loading properties of the NCs are characterized by scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectrophotometer, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The favorable performance of Ni coating after incorporation of NCs is demonstrated by potentiodynamic polarization (PDP), linear polarization, and electrochemical impedance spectroscopy. Based on the results of PDP test, the corrosion current density (i_c) of the MBT@NCs (MNCs)-engineered Ni coating reduces slightly from 6.4 to 5.4 μA cm⁻² after immersion in a corrosive media, while the value for MNCs-free coating increases by almost a factor of ten from 6.8 to 67.4 μA cm⁻². Our findings demonstrate the possibility of using corrosion inhibitors loaded NCs to enhance the corrosion resistance of a metallic coating and give new perspectives for functionalization of a metallic coating with nanomaterials.