Fully additive manufacturing of PC/AlSi10Mg hybrid joints with surface structured substrate: a promissing approach for lightweight applications

This study presents a novel approach to joining polycarbonate (PC) with additive-manufactured AlSi10Mg alloy through AddJoining – a new approach using fused filament fabrication (FFF) to hybridize metal parts. The hybrid joints were entirely produced by additive manufacturing without additional adhesive or fasteners. The AlSi10Mg substrate was designed and 3D-printed by Laser-powder bed fusion (L-PBF) with surface structures in the submillimetric scale to enhance the mechanical interlocking between the deposited FFF polymer and L-PBF metal. The effect of different 3D-printed submillimetric surface structures – i.e., as-built, inkpot-like, lattice and mushroom-like - on the quasi-static single-lap joint strength was investigated. The results showed that the hybrid joints with mushroom-like exhibited the highest mechanical strength (lap-shear strength of 10.8 ± 0.6 MPa) compared to the as-built AlSi10Mg surface (lap-shear strength of 3.5 ± 0.2 MPa). The submillimetric surface structures on the AlSi10Mg substrate significantly improved the joint strength, and the joint failure shifted from adhesive to cohesive failure by adding the surface structures. Apart from the high specific strength of the hybrid joints, the attractive characteristics of the AddJoining process can potentially support circular economy principles. Since AddJoning can reduce material usage, it works with thermoplastic polymers - known for their excellent recyclability - potentially enabling the production of recyclable hybrid structures, offers potential lower energy consumption compared to the state-of-the-art manufacturing process. The hybrid joints described offer enormous potential for lightweight applications, such as the automotive and aerospace sectors, because they can potentially help reduce structural weight without affecting mechanical performance. Moreover, using FFF and L-PBF technologies allows for the development of complicated and bespoke structure geometries, making the suggested hybrid structures applicable to various industries.