Enhancing structure integrity and corrosion resistance of Mg alloy by a two-step deposition to avoid F ions etching to nano-SiO2 reinforcement

摘要

The enhancement of corrosion resistance depends heavily on functionalization of surface coating during plating. The addition of nano-SiO2 particles (NSPs) into electroless nickel plating (ENP) bath provides a possibility to produce functionalized coatings with a wider range of compositions for enhancing corrosion resistance. This report describes a new approach to functionalization of the coating on Mg alloy by using duplex-layers with NSPs incorporated in the outer layer. The effect of the NSPs on the microstructure, composition and corrosion resistance of the coatings was investigated by an array of analytical techniques, including scanning electron microscope (SEM), energy dispersive spectrometry (EDS), and Xray diffraction (XRD), and potentiodynamic polarization (PDP) measurement. The results show that the incorporation of NSPs produces a more uniform and smoother coating surface compared with the coating that without NSPs. The corrosion resistance of the new prepared coating is better than that of single coating, which also depends on detailed preparation methods. An optimum concentration of NSPs in the plating bath for the highest enhancement in corrosion resistance in aggressive NaCl and HCl mediums has been identified. The mechanism of how the NSPs influence the corrosion resistance is also discussed. (C) 2017 Elsevier B. V. All rights reserved.