Corrosion Sensitivity of Graphene Doped Micro-arc Oxidation Film of Magnesium-lithium Alloy in Cl⁻ Solution

In order to find out the effect of graphene on the corrosion sensitivity of micro-arc oxidation (MAO) film of magnesium-lithium alloys, a modified MAO film was prepared on the surface of magnesium-lithium alloy by adding graphene to the electrolyte of silicate system. The electrochemical susceptibility of the modified film in NaCl solution of different concentration was studied by electrochemical polarization and electrochemical impedance spectrum methods. The results show that the addition of graphene can effectively improve the pores, micro-cracks and other defects due to micro-arc discharge, and improve the film density and corrosion resistance. The corrosion resistance of the modified MAO film decreases with the concentration of NaCl solution increasing. It is mainly due to the accelerated diffusion of aggressive ions into the film under the action of higher concentration gradient, accelerating the corrosion of the MAO film.