PFAS-free laser-textured triple-scale architectures for durable passivation against pitting corrosion of aluminum alloys
摘要
Scalable manufacturing of multifunctional metal surfaces requires precise control over surface topology, chemistry, and interfacial stability. Here, we report a nanosecond laser-enabled strategy integrating hierarchical structuring with PFAS-free chemical functionalization to engineer triple-scale architectures on AA6061 aluminum alloy. Nanosecond fiber laser texturing generated fully covered grid and grid-with-double-diagonal patterns composed of microscale trenches, submicron resolidified ridges, and nanoscale cauliflower-like features formed through photothermal melting and rapid solidification. The oxide-enriched laser-textured surface provided reactive hydroxyl sites that enabled covalent attachment of a non-fluorinated siloxane network through immersion-based OTS-PDMS treatment, producing a mechanically anchored hybrid layer. This morphology-chemistry coupling established a stable Cassie–Baxter wetting regime with water contact angles up to 158°, roll-off angles near 2°, and low contact angle hysteresis. The grid-with-double-diagonal architecture ensured uniform oxide modification and silane anchoring across large areas, demonstrating manufacturability. Electrochemical testing in 0.6 M NaCl showed significantly reduced corrosion current density, elevated pitting potential, and up to three orders-of-magnitude higher impedance than untreated aluminum, demonstrating durable interfacial performance in aggressive environments.