Synthesis and analysis of superhydrophobic hybrid coatings on shape memory alloys via immersion method

Abstract

Shape memory alloys (SMA) treated by laser cladding (LC) offer the benefits of a controlled heat-affected zone and strong metallurgical bonding between the coating and substrate, while also reducing the residual stress typically associated with the LC process. However, their limited corrosion resistance has hindered further application and development. In this study, an organic/inorganic hybrid superhydrophobic coating was developed on the surface of Fe-Mn-Si-Cr-Ni-Nb SMA using 1H, 1H, 2H, 2H-perfluorododecyltrimethoxysilane (FDTS) as a low surface energy material, hydrophobic nano-SiO₂ to induce surface roughness, and anhydrous ethanol as a solvent. The coating retained its superhydrophobic properties even after exposure to temperatures ranging from − 70 to 200°C. It demonstrated a silver mirror phenomenon in both strong acids and deionized water, and the surface remained dry after removal from these solutions, underscoring its excellent superhydrophobic performance. Moreover, the superhydrophobic coating achieved a reduction in corrosion current density by more than half and nearly doubled the corrosion potential, marking a significant enhancement in corrosion resistance compared to uncoated SMAs. The incorporation of FDTS with nano-silica effectively addressed the inherent corrosion challenges of SMAs, providing new strategies for the preparation and modification of Fe-based SMA coatings and offering substantial support for the research and industrial production of advanced functional coatings.