Significant physicochemical differences between metals and thermoplastics pose challenges for achieving strong interfacial bonding under conventional forming processes. This work presents a novel approach using an external electric field (EEF) to activate functional groups at metal-polymer interfaces, forming complex chemical bonds and strong heterogeneous connections. Silane-modified PA66 composites filled with high-content aluminum spheres were fabricated. Experimental results show that the chemical bonding between Al and PA66 under EEF is due to extensive functional group reactions and secondary bonding within Al-PA66 interface, achieving a remarkable ultimate tensile strength of 65 MPa for the composite with 50 wt% Al filling. Moreover, dissimilar joints of composites and 6061T6, made by friction stir welding, exhibit high strength due to the formation of a “Novel Net-Metallurgy Bonding Structure” during frictional heat transfer. This work provides new insights and theoretical guidance for interfacial bonding in metal-polymer heterogeneous interfaces.
The increasing power density of chips poses a significant challenge in the form of material aging for aluminum-filled polydimethylsiloxane (Al/PDMS) composites, which are widely used in thermal interface materials. Despite the growing importance of this issue, the specific mechanisms behind the interfacial aging process remain elusive, hindering a comprehensive grasp of the aging dynamics in these composites. In our research, we have developed an in-situ Raman aging monitoring system that leverages the non-contact and high-resolution capabilities of Raman spectroscopy to study the interface aging process. Our findings indicate a notable decrease in the intensity of the Raman peak as further cross-linking of the molecules during aging, with the most pronounced decline occurring at the interface between aluminum and PDMS. This insight could potentially elucidate why the interface in composite materials is frequently the site of failure during aging. Our study offers a versatile methodology for investigating the interfacial aging of polymer composites, contributing to a broader understanding of the interface behavior in composite materials at the molecular level.
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