Biomimetic liquid infused surface based on nano-porous array: Corrosion resistance for tin metal and self-healing property

Tin material corrosion has been recognized as an important problem for electronic products. Biomimetics strategies have been adopted to develop intriguing materials to combat corrosion. In this paper, by anodic oxidation, mussel inspired dopamine hydrochloride modification and thiol grafting, lotus leaf inspired superhydrophobic surface (SHS) based on porous SnO2 coating is prepared on tin. Further, a stable liquid infused surface (LIS) enlightened by Nepenthes plant is formed by infusing dimethyl silicone oil into SHS. The wettability, microstructure and chemical composition of tin surface with different modification are characterized by contact angle, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and so forth. The porous SnO2 structure endows superhydrophobicity with a contact angle up to 155.9°. The corrosion resistance of SHS and LIS coating is revealed by scanning Kelvin probe (SKP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) curves. Corrosion data show that the prepared LIS exhibits better corrosion resistance than SHS. After being soaked in a representative 3.5 wt% NaCl solution for 180 h, the corrosion inhibition efficiency of LIS maintains 99.6%, which is much better than that of SHS. In addition, when being fold or bent to induce cracks, the LIS shows slight change in corrosion inhibition efficiency, indicating the high tolerance to mechanical torsion. Moreover, in response to externally imposed mechanical scratching, LIS demonstrates good self-healing capability, illustrating the high potential for practical usage.