Polymer-Metal Adhesion of Single-Lap Joints Using Fused Filament Fabrication Process: Aluminium with Carbon Fiber Reinforced Polyamide

Additive manufacturing (AM) is often used for prototyping; however, in recent years, there have been several final product applications, namely the development of polymer-metal hybrid (PMH) components that have emerged. In this paper, the objective is to characterize the adhesion of single-lap joints between two different materials: aluminium and a polymer-based material manufactured by fused filament fabrication (FFF). Single-lap joints were fabricated using an aluminium substrate with different surface treatments: sandpaper polishing (SP) and grit blasting (GB). Three filaments for FFF were tested: acrylonitrile butadiene styrene (ABS), polyamide (PA), and polyamide reinforced with short carbon fibers (PA + CF). To characterize the behaviour of these single-lap joints, mechanical tension loading tests were performed. The analysis of the fractured surface of the joints aimed to correlate the adhesion performance of each joint with the occurred failure mode. The obtained results show the impact of surface roughness (0.16 < Ra < 1.65 µm) on the mechanical properties of the PMH joint. The ultimate lap shear strength (ULSS) of PMH single-lap joints produced by FFF (1 < ULSS < 6.6 MPa) agree with the reported values in the literature and increases for substrates with a higher surface roughness, remelting of the primer (PA and PA + CF), and higher stiffness of the polymer-based adherent.