Corrosion resistance of AZ31B magnesium alloy with a conversion coating produced from a choline chloride—Urea based deep eutectic solvent

A novel ionothermal strategy for developing a chemical conversion film on magnesium alloys is proposed based on the interaction of a deep eutectic solvent (DES) with the substrate. Upon heating the choline chloride/urea mixture-based DES can react with the AZ31B magnesium alloy surface to form a promising anti-corrosion conversion film. Interestingly, the chemical conversion film is mainly composed by MgH 2 and MgCO 3 phases. The as-grown conversion film exhibits superhydrophobicity after surface modification in a stearic acid/ethanol solution. Electrochemical tests and visual investigations indicate the corrosion resistance of the magnesium alloy can be improved by the conversion film.