Multi-functional superhydrophobic coatings on MgLi alloys via SiO2 nano particles assembled surface modification

A multi-structured composite coating with superhydrophobic properties, corrosion resistance, and wear resistance was prepared on the surface of Mg-9Li-3Al alloy. A porous layer was formed on the substrate surface via micro-arc oxidation. Then, LDH was grown in situ on the MAO coating surface through hydrothermal treatment, sealing the pores in the coating. Finally, HDTMS-SiO₂ was assembled on the LDH surface. The SiO₂ formed an island-like micro-nano structure, trapping air and creating an “air cushion” on the coating surface，imparting superhydrophobicity (contact angle and sliding angle of 162.1 ± 2.1° and 4.2 ± 0.2°). And the corrosion resistance of the MLS coating is significantly improved the corrosion current density decreased by three orders of magnitude. The incorporation of HDTMS-SiO₂ not only improved the corrosion resistance of the coating but also significantly enhanced its wear resistance. During friction, the SiO₂ nanoparticles acted as “ball bearings,” shifting the friction mode from sliding to rolling. The fragmented SiO₂ further served as a solid lubricant, reducing the coefficient of friction to 0.11.