Highlighting chemical bonding between nylon-6.6 and the native oxide from an aluminum sheet assembled by laser welding

Polymer/metal hybrid assemblies are well suited for automotive and biomedical applications because of their ability to create lightweight structures with a wide range of design possibilities. Laser welding is a promising technique for joining dissimilar materials thanks to its quickness, freedom of design and absence of adhesives. Still, the fundamental causes of adhesion in hybrid laser welding remain not well understood. Therefore, the present work aims at highlighting a chemical bonding between a polymer, nylon-6.6, and a metal, aluminum. To access the interface information, the samples were first broken, leaving a residue on the surface, which was dissolved afterward. The chemical reactive sites of the nylon molecule able to react with aluminum surface were suggested and the feasibility of these reactions was analyzed in light of the results obtained by means of X-ray photoelectron spectroscopy (XPS) and time of flight secondary electron microscopy (ToF-SIMS).