Study on Hydrophobic Surface of Magnesium Alloy Prepared by Femtosecond Laser and its Corrosion Resistance

Abstract Due to their excellent barrier and shielding effects, superhydrophobic magnesium alloy surfaces are increasingly interested in corrosion protection. This paper proposes a method for producing a stable superhydrophobic surface by laser scanning ablation of AZ31B magnesium alloy on its surface. The prepared layered micro-nanoemulsion convex structure with a lotus-like surface exhibited excellent superhydrophobicity after modification by stearic acid, and the static water droplet contact angle reached 163°. After 90 days in outdoor air, droplet pressure-based experiments show that the superhydrophobic surface possesses a long-term stable Cassie state. In addition, The superhydrophobic surface showed excellent corrosion resistance against magnesium alloy in a Neutral 3.5 wt.% NaCl solution. The results of the dynamic potential polarization tests showed that the existence of a gas layer cavity on the lotus-like surface structure caused the corrosion current density of superhydrophobic AZ31B (3.86±1 uA/cm2) to decrease by 2 orders of magnitude compared with that of the extruded AZ31B (103±1 uA/cm2). We believe the proposed method is simple, efficient, and non-polluting, especially for medical magnesium alloys in the field of in vivo implant materials to slow down corrosion and promote clinical applications.