Bioinspired superhydrophobic surface via one-step electrodeposition and its corrosion inhibition for Mg-Li alloy

The extremely low corrosion resistance of Mg-Li alloy is a critical obstacle to overcome for its practical usage. In this work, targeting this hard problem, we prepare bioinspired superhydrophobic surface onto Mg-Li (LA141) alloy (contact angle up to 167.4° with the sliding angle as low as 1°) for corrosion prohibition by a facile one-step electrodeposition. Transient image capture technique reveals the dynamic interaction between water droplet and superhydrophobic surface, demonstrating the strong repellency to water phase. Superhydrophobic surface plays an essential role in limiting the time of wetness, so that the opportunity for corrosion will be substantially decreased. In atmospheric condition, the corrosion inhibition capability of superhydrophobic coating to Mg-Li alloy is revealed by scanning Kelvin probe. In water immersion state, the electrochemical impedance spectroscopy and the potentiodynamic polarization curve technique is used to uncover the corrosion resistance of the superhydrophobic coatings prepared under different voltage and time. The electrochemical impedance obtained at 40 V after electrolysis for 30 min is up to 5.62 × 105 Ω cm2, which is about 104 times larger than that of the bare state Mg-Li alloy. Meanwhile, the corrosion current density is about 4.36 × 10−8 A/cm2, which is ca. 4 orders of magnitude lower than that of bare Mg-Li alloy, suggesting great corrosion resistance property of the prepared coating in this work.