Superhydrophobic and corrosion-resistant coating on AlSi10Mg alloy via stearic acid etching and amino-modified SiO2/epoxy composite deposition

A superhydrophobic and anti-corrosive coating was fabricated on AlSi10Mg alloy through a two-step approach combining stearic acid etching and spray deposition of an amino-modified silica/epoxy composite. The hierarchical micro/nanostructure required for superhydrophobicity was achieved through the synergistic effect of substrate roughening induced by stearic acid etching and the cross-linked micro/nano-features formed during epoxy resin polymerization. Surface energy reduction was accomplished by the aligned long-chain alkyl groups generated from the stearic acid-aluminum reaction, along with the incorporation of polydimethylsiloxane (PDMS) and polytetrafluoroethylene (PTFE) grafted onto the modified silica nanoparticles. Notably, the coating maintained its superhydrophobic properties after 96 h of salt spray testing, demonstrating excellent corrosion protection for the substrate. The combination of chemically bonded low-surface-energy components and mechanically stable hierarchical structures resulted in durable water repellency and enhanced anti-corrosion performance. • Stearic-acid etching created micro-roughness on additively manufactured AlSi10Mg. • Silane-modified nano-SiO₂ enhanced hydrophobicity and interfacial bonding. • Coral-like micro-nano structure enabled synergistic superhydrophobicity. • Robust coating exhibited salt-fog resistance and corrosion protection.