Enhancing interfacial adhesion of induction welded CF/PA66 joints via fabricating a hierarchical micro-nano porous structure on heating element

The development of efficient and reliable bonding techniques for thermoplastic composites was crucial for lightweight and high-performance structural applications in industries such as automotive and aerospace. This study investigated the use of aluminum mesh as a heating element (HE) for the induction welding of thermoplastic composites, aiming to produce lightweight and high-strength joints. A hierarchical micro-nano porous structure was developed on the HE surfaces via an anodization and acid etching (AAE) treatment to enhance the interfacial adhesion between the HE and resin matrix. The results showed that the hierarchical micro-nano porous structure significantly increased HE surface roughness and hydroxyl adsorption, improving wettability and promoting mechanical interlocking between HE and the resin matrix during welding. Interface analysis further demonstrated that this micro-nano structure also facilitated stronger Al-O-C bond interactions between HE and resin matrix. As a result, under the synergistic effect of mechanical interlocking and chemical bonding at the HE/PA66 interface, the lap shear strength (LSS) of the AAE-treated joints increased by 45.5 %, reaching 16.06 MPa. Digital image correlation (DIC) technique analysis revealed that the hierarchical micro-nano porous structure effectively alleviated strain concentration at the weld seam. Overall, the introduction of the hierarchical micro-nano porous structure on the HE surfaces significantly improved weld seam uniformity and joint strength, providing an innovative solution for the efficient and reliable joining of thermoplastic composites.