The effect of adding polyethylene glycol to electrolyte solution on micro-arc oxidation coating on pure aluminum

Micro-arc oxidation (MAO) is a surface treatment technology that enhances the performance of metal surfaces by growing ceramic layers on the valve metal surface to meet the demand of the application. This paper aims to improve the performance of ceramic coatings on pure aluminum surfaces by varying the concentration of polyethylene glycol (PEG) in electrolytes. As an active agent, the PEG extends the ionic activity, and the increasing rate of ion migration in electrolytes improves the reaction rate. And the PEG long chain is also beneficial to electron conduction, which will promote the discharge effect in the MAO process. The MAO coating was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), the wear resistance of MAO coating was evaluated by tribological experiments, and the corrosion resistance of MAO coating was evaluated by the Neutral salt spray test (NSST). The experimental results showed that the MAO coating had the best wear resistance when the concentration of PEG was 2 g/L. The coatings prepared by adding PEG to the electrolyte have good wear and corrosion resistance, which enhance the service life and application range of the metal and are expected to promote the development of valve metal in application fields.