Surface treatments for polymer composite welding: A systematic review

Welding of polymer composites, for like-material (composite/composite) and dissimilar (composite/metal) combinations, is a promising alternative to conventional joining methods in sectors such as aerospace and automotive, yet achieving robust joints is critically dependent on optimal interfacial bonding. The primary objective of this systematic review is to evaluate the comparative effectiveness of surface treatment strategies applied prior to welding, based on material properties, process variables, and application contexts. Employing a bibliometric and SWOT analysis, this study categorizes techniques into seven main groups: abrasive, laser texturing, plasma, etching, chemical oxidation, intermediate film application, and nanofiller incorporation. These methods are assessed by how they modify surface properties to enhance mechanical anchoring and chemical interactions. The analysis reveals a multifaceted choice of treatment, highly dependent on the specific materials and welding process, with recurring effective strategies: for like-material joints, robust performance is achieved through compatible thermoplastic films, often combined with plasma or nanofillers, whereas for dissimilar joints, an effective combination strategy frequently involves abrasive preparation, oxide layer growth, and silane deposition to increase roughness and chemical compatibility. This review establishes that engineered surface treatments and their strategic combinations are fundamental for enabling reliable, high-performance welded joints, thereby advancing the application of lightweight composite structures.