Characterization of plasma electrolytic oxidation coatings formed on Mg-Li alloy in an alkaline silicate electrolyte containing silica sol

We investigate the influence of silica Sol addition on the ceramic coatings of Mg-Li alloy by plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy are employed to characterize the microstructure and composition of the ceramic coatings. The anti-corrosion behavior of the ceramic coatings is evaluated by potentiodynamic polarization measurements in conjunction with electrochemical impedance analysis. The ceramic coating formed in the electrolyte containing silica Sol contains SiO2 and Mg2SiO4 phase and has more uniform morphology and higher corrosion resistance than that formed in the electrolyte without addition of silica Sol.