Mechanical bonding of dissimilar materials via anchor-based interfacial interlocking

This study proposes a cold underwater shock wave bonding process for joining polymer sheets to metal substrates. High-pressure loading generated in water presses the polymer into pre-formed grooves on the metal surface, creating mechanical interlocking without heat or adhesives. The approach is applicable to thermoplastics, thermosetting resins, and low-surface-energy materials (e.g., PTFE), and is particularly suited for bonding heat-sensitive or functional polymer sheets carrying micro/nanostructures. Bonding experiments were conducted using stainless steel (SUS304) substrates and various sheets (PTFE, PI, PET, PC), with aluminum included for comparison. The bonding interfaces and deformation behaviors were examined by microscopy techniques, and Smoothed Particle Hydrodynamics (SPH) simulations reproduced polymer flow and substrate deformation, consistent with localized plasticity enhancing interlocking. Quantitatively, bonding grooves closed by ∼30 % across materials, and tensile-type peeling test on Al/SUS304 confirmed interfacial strength exceeding the adhesive layer. Using water as a flexible medium preserved functional micro/nanostructures during bonding. The results demonstrate the feasibility of underwater shock wave bonding as a robust polymer-metal integration technique: PC, PTFE, and PI achieved successful bonding without significant defects, while PET showed brittle fracture behavior that requires further parameter optimization. Overall, the process enables instantaneous, reliable bonding without thermal damage, with potential applications in automotive, aerospace, and biomedical devices. • Developed a cold bonding process using underwater shock waves to join polymers to grooved metals without heat or adhesives. • Demonstrated applicability to polymers including PC, PTFE, and thermosetting PI, but not brittle PET. • Preserved micro/nanostructures on the water side while allowing large deformation on the substrate side. • Clarified polymer flow–substrate deformation interaction forming strong interlocking, supported by simulation.