Achieving the thermal reinforcement between aluminum sensing elements and composites in induction welding via silane layers

Abstract

The surface modification of aluminum sensing elements (SEs) was conducted using three distinct silane coupling agents: γ-aminopropyl trimethoxy silane (ATS), γ-glycidoxypropyl trimethoxy silane (GTS), and γ-methacryloxypropyl trimethoxy silane (MTS). These modified SEs were subsequently employed in the induction welding of carbon fiber reinforced thermoplastic composites (CFRTP). The improved adhesion work at the modified SE/CFRTP interface facilitated the spreading of CFRTP across the SE surface. Microscopic examination of the weld cross-section demonstrated a reduction in porosity defects, and the jagged fracture morphologies approved strong adhesion between matrix and siloxane network. Furthermore, the formation of Al–O–Si covalent bonds at the silane/SE interface augmented interfacial thermal conductivity, thereby optimizing the heat transfer process at the SE/CFRTP interface. This enhancement improved the uniformity of the interfacial temperature distribution and reduced the residual stress at the joints. Ultimately, the combination of adhesion enhancement at the interface and improved thermal conductivity enabled the GTS-treated SE to achieve the maximum lap shear strength (LSS) of 15.9 MPa for the joints, representing a 1.7 times improvement compared to pretreated joints. The residual strength following hygrothermal aging was also improved due to good interfacial bonding.