Study of Barrier Property of Composite Film Coated on Mg-Gd-Y Alloy by Water Diffusion

A composite film was prepared by depositing layers of plasma electrolysis oxidation (PEO) film and self-assembled nanoparticle (SANP) film on a Mg-Gd-Y alloy. The electrochemical impedance spectroscopy (EIS) results showed that the structure of the PEO + thin SANP layers greatly increased the corrosion protection of the composite film. In addition, two water diffusion coefficients (D) of the composite film were obtained using EIS and Kalnin's model. The Dvalues indicated the composite film had a good barrier property against water.