Using Radio‐Frequency Fields for Local Heating and Curing of Adhesive for Bonding Metals

Lightweighting of metal structures can be achieved by replacing metallic fasteners with thermosetting adhesives. However, thermal curing of adhesives to bond metals in an oven can lead to distortions due to mismatched coefficients of thermal expansion, thereby compromising the structural integrity. Targeted heating of the adhesive can be utilized to minimize distortions and residual stresses in metal‐composite assembly. Herein, it is shown that rapid heating of carbon nanoparticles in the presence of radio‐frequency (RF) electromagnetic fields can be used to cure nanocomposite adhesives for bonding metal substrates selectively. Using the metal components of a structure as a part of an RF circuit, electric fields are generated through a carbon‐nanofiller loaded adhesive, which then volumetrically heats and cures. Comparable lap‐shear strengths and adhesive peel resistance are measured for RF‐ and oven‐cured composites. RF‐cured multimaterial bonding specimens (aluminum‐to‐steel) show minimal distortion, resulting in ≈590% higher fracture energies in peel mode as compared with oven‐cured specimens.