A robust superhydrophobic surface on AA3003 aluminum alloy with intermetallic phases in-situ pinning effect for corrosion protection

The tendency of AA3003 towards localized corrosion is one of the most challenging issues for its broader use. Intermetallic phases (IMPs) in AA3003 play dual contradictory roles: strengthening effect and initiating pitting. Solving this contradiction contributes to improvement of corrosion resistance and fully utilizing the potential of materials. Herein, a superhydrophobic surface with IMPs in-situ pinning effect was fabricated via a chemical etching approach combined with stearic acid (STA) modification. Thus, IMPs can provide sound support for the superhydrophobic surface and meanwhile eliminate the adverse effect of promoting localized corrosion. Formation mechanism of etching structure was attributed to the synchronous chemical reaction of IMPs and matrix phases in the etchant. Further modification with STA changed mico/nano hierarchical surface from hydrophilicity to superhydrophobicity. The as-prepared surface exhibited a maximum static contact angle of ~169° and a sliding angle of ~1°, possessing excellent superhydrophobicity. Besides, the wettability, self-cleaning, chemical stability, mechanical durability, and corrosion resistance properties of the superhydrophobic surface were comprehensively investigated. The results showed that the corrosion inhibition efficiency exceeded 99% in 3.5 wt% NaCl solution. The pinning direction of IMPs in superhydrophobic surface influenced its properties. It is anticipated that the construction of superhydrophobic surfaces will broaden its promising applications.