Improving Electrochemical Corrosion Property of Magnesium Alloy Prepared by the Combination of Ultrasonic Shot Peening and Laser Etching

This paper utilizes a combination of ultrasonic shot peening (USP), laser etching (LE), and chemical modification (CM) to prepare hydrophobic surfaces on AZ31b magnesium alloys. The corrosion resistance of the magnesium alloy was examined by electrochemical corrosion experiments. The results showed that USP introduced a grain refinement layer and a compressive residual stress layer. After LE on the USPed sample, the sample surface exhibits both macro- and micro-undulations, which improves the adsorption efficiency of the stearic acid. The magnesium alloy treated with USP + LE + CM showed superhydrophobicity with a contact angle 158.5°. The USP pre-treatment increased the superhydrophobic film resistance and charge transfer resistance of the LE + CM sample by more than 2 times, demonstrating excellent corrosion resistance in a 3.5% NaCl solution. The reason for the improved corrosion resistance of the USP + LE + CM samples is that the superhydrophobic surface reduces the contact between liquid and surface, and the refined grains and compressive residual stress layer improve the integrity of the passivation film.