Synergistic heating effect via CNT/Fe3O4 nanocomposite aerogels enabling uniform and rapid induction welding with high bond strength in CFRTPs

Effective induction welding of carbon fiber-reinforced thermoplastic composites (CFRTPs) requires both uniform temperature distribution and rapid heating at the welding interface. However, achieving both is challenging because heat localizes due to non-uniform magnetic-field distribution and the difficulty of forming current loops within the composite structure. In this study, a powdered CNT/Fe ₃ O ₄ /PA6 aerogel (Nanocomposite) was adopted to enhance induction-heating performance by simultaneously leveraging electrical conductivity and magnetic-loss mechanisms. The nanocomposite contains carbon nanotubes (CNTs) that form continuous conductive pathways, enabling efficient Joule heating and improved heat transfer. The CNTs also act as nanoscale mechanical pins that bridge CFRTPs, thereby enhancing interfacial weld strength. In addition, embedded Fe ₃ O ₄ particles respond rapidly to the alternating magnetic field and act as localized heat sources via magnetic losses, increasing heating efficiency. As a result, the nanocomposite-enabled system demonstrated a 94.6% higher initial heating rate and a 57% reduction in the time required to reach the target processing temperature at the welding interface. The interfacial shear strength increased by 30.8%, and fracture-surface analysis revealed more uniform melting and more effective impregnation across the weld area. These results indicate that the proposed nanocomposite offers a promising strategy for achieving both rapid and uniform heating, leading to improved mechanical performance in the induction welding of CFRTPs.