Removable metallic susceptor for induction welding of thermoplastic composites

초록

Induction welding of thermoplastic composites typically relies on metallic susceptors, which remain embedded in the joint and introduce unnecessary mass and interfacial discontinuities. Here, we introduce a low-melting-point alloy as a removable metallic susceptor for induction welding. Field's Metal (In–Bi–Sn, melting point 62 °C) provides a conductive pathway for induction heating, then liquefies and is expelled during consolidation, leaving <2.5 wt% residue. Owing to the phase-transition-induced increase in electrical resistivity, the removable susceptor achieves heating rates exceeding 20 °C/s with improved temperature uniformity. A pneumatic direct-writing system combined with a machine-learning-assisted path design workflow enables controlled deposition and extension to complex geometries. The approach is validated by welding polyetherimide (PEI) substrates and further demonstrated for unidirectional (UD) polyetherketoneketone (PEKK) carbon fiber reinforced thermoplastic (CFRTP) laminates, where conventional induction welding is ineffective. This strategy provides a new route for rapid and structurally efficient induction welding without permanent susceptor inclusion. © 2026 Elsevier Ltd

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