A stearic Acid/CeO₂ bilayer coating on AZ31B magnesium alloy with superhydrophobic and self-cleaning properties for corrosion inhibition

Corrosion is one of the most challenging issues for the large-scale application of magnesium alloys. Fabricating a superhydrophobic surface with a low-cost, easy-to-handle method is meaningful for anti-corrosion protection of Mg alloys. In this study, a stearic acid/CeO₂ bilayer coating was prepared on AZ31B Mg by a simple electrodeposition method combined with immersion in stearic acid solution. The growth traits of the coating with different electrodeposition current densities and time were evaluated, which demonstrated that 60 min combined with 0.65 mA/cm² is the optimal electrodeposition condition. Besides, the wettability, anti-corrosion ability, durability, chemical stability and self-cleaning properties of the coating were comprehensively investigated. The results showed that the as-prepared coating exhibited a good superhydrophobic and self-cleaning property with CA>158° and SA<2°. Moreover, the coating demonstrated an improved anti-corrosion performance in 3.5 wt% NaCl solution and was quite stable in the atmosphere and in contact with pH droplets of 1–13.