Fluorine-free laser-textured superhydrophobic surfaces on 3003 aluminum alloy

3003 aluminum alloy is widely used in heat exchangers and new energy vehicle battery casings, but its hydrophilic surface is susceptible to water accumulation, fouling, and icing. In this study, a fluorine-free bioinspired superhydrophobic surface was fabricated on 3003 aluminum alloy by nanosecond laser texturing followed by low-temperature heat treatment, using the hierarchical morphology of Metaplexis japonica leaves as a structural reference. Circular-array laser textures were optimized by response surface methodology. Under the optimized parameters, the treated surface achieved a water contact angle (WCA) of 156.2 ± 0.5°. Morphological and chemical analyses indicated that the superhydrophobicity originated from the synergistic effect of laser-induced hierarchical micro/nanostructures and heat-treatment-induced surface chemical evolution. The formed micro-pits, protruded recast structures, and redeposited nanoparticles promoted air retention, while carbonaceous species reduced the apparent surface free energy. The treated surface also showed improved self-cleaning performance, delayed droplet freezing, and retained hydrophobicity after short-term vibration wear. This work provides a feasible fluorine-free strategy for developing water-repellent 3003 aluminum alloy surfaces with self-cleaning and freezing-delay potential.