Remarkably Enhancing the Bonding Performance of Aluminum Alloy/ CFRE Hybrid Joints by Directionally Inducing Covalent Bonds and Mechanical Interlocking via Shark Scale Structures and Silane‐Functionalized Interfaces

Interfacial bonding properties critically influence the performance of metal/epoxy composites. This study introduces a surface treatment combining a shark shield scale biomimetic structure and silanization to enhance the interfacial bond strength of aluminum alloy/short carbon fiber reinforced epoxy (CFRE) joints. Surface morphology, roughness, and elemental changes were characterized using laser confocal microscopy and XPS, while wettability and bonding performance were evaluated via contact angle measurements and single‐lap shear tests. The combined treatment increased the initial lap‐shear strength to 12.52 MPa, representing a substantial increase over the pre‐treated baseline (As). Fracture‐surface observations suggest a transition from predominantly interfacial failure toward increased cohesive involvement after the combined treatment. The enhancement is attributed to the synergistic contributions of mechanical interlocking enabled by the shark shield scale texture and a silane‐functionalized interphase that strengthens interfacial interactions (consistent with possible Al–O–Si linkages). This work emphasizes improved initial bonding performance under ambient conditions; durability (e.g., hygrothermal aging, salt spray, and fatigue) will be addressed in future work.