Laser-induced superhydrophobic surface of 1420 Al–Li alloy: corrosion resistance comparison between grating and grid patterns

Based on the strategy of enhancing the metal corrosion resistance through superhydrophobicity, two types of superhydrophobic surfaces—grating (anisotropic) and grid (isotropic) —were successfully fabricated on the surface of 1420 aluminum-lithium (Al-Li) alloy by laser etching. The study investigated the differences in corrosion resistance between these two superhydrophobic surfaces. The results showed that both superhydrophobic surface exhibited needle-like nanostructures. As the volume of surface droplets increased, the contact angle gradually decreased and the rolling angle increased, eventually causing the droplets to pin to the surface. The grid surface showed droplet pinning earlier than the grating surface. Electrochemical tests confirmed the improved corrosion resistance of the superhydrophobic surfaces. The self-corrosion potential was increased from -0.851V (bare Al-Li alloy) to -0.644V for the grid surface and -0.622V for the grating surface. Correspondingly, the corrosion current was significantly decreased from 0.316 A/cm 2 to as low as 0.575×10 -7 A/cm 2 (grid surface) and 0.457 × 10 -7 A/cm 2 (grating surface). Furthermore, compared to the grid superhydrophobic surface, the grating surface demonstrated a larger impedance radius. The charge transfer resistance ( R ct ) also increased from 1372Ω•cm 2 (grid surface) to 2252 Ω•cm 2 (grating surface), further indicating its superior corrosion resistance. This work provides valuable insights for the design of anti-corrosion metal surfaces.