Rapid preparation of superhydrophobic and corrosion-resistant surfaces based on etching-assisted phosphating modification and analysis of their corrosion resistance mechanisms

Rapid, mild, and scalable routes to superhydrophobic corrosion-resistant surfaces are highly desired for light alloys. Here, we report a two-step process that combines etching-assisted phosphating with Al(H2PO4)3 and a subsequent low-surface-energy modification. The treatment builds a micro/nano hierarchical texture together with a phosphate/hydroxide conversion layer within <1 h, yielding a superhydrophobic interface with a static water contact angle of ∼166.9°. Electrochemical impedance spectroscopy (3.5 wt. % NaCl) evidences a pronounced barrier effect, with the low-frequency |Z| at 0.01 Hz reaching ∼108 Ω cm2, and remaining high over 1 h/24 h/7 d immersion. Equivalent-circuit analysis (two time constants) together with postexposure SEM supports a dual-protection mechanism in which the superhydrophobic top layer blocks electrolyte access while the conversion layer passivates the substrate. Mechanical and chemical stability tests further confirm robust performance under abrasion and saline/alkaline exposures. Overall, this mild and time-efficient strategy balances anticorrosion efficacy with wettability control and manufacturability, offering a practical route for protecting light-alloy surfaces.