Anti-corrosion behaviour of superwetting structured surfaces on Mg-9Al-1Zn magnesium alloy

Abstract Superhydrophilic and superhydrophobic surfaces were prepared on a rolled Mg-9Al-1Zn magnesium alloy (AZ91) sheet via the combination of simple laser ablation and annealing treatment. After annealing at 160 °C for 60 min, laser ablated superhydrophilic surface transformed into superhydrophobic surface with a water contact angle (WCA) as high as 158.8 ± 2°. Superwetting surfaces, including superhydrophilic and superhydrophobic surfaces, exhibit higher corrosion resistance based on the results of potentiodynamic polarization curves and electrochemical impedance spectroscopy. The corrosion inhibition mechanism of the superwetting surfaces are that, Al element in high volume fraction of fine-spherical Mg 17 Al 12 phases changed to solid-solution aluminum within the melted layer for superhydrophilic surface and the air layer stored by micro/nanostructure could hold back erosive solution for the superhydrophobic surface. It's believed that the facile and highly-efficient method will make magnesium alloys a better engineering application prospects.