The Influence of Coating and Adhesive Layers on the Mechanical Performance of Additively Manufactured Aluminum-Polymer Hybrid Joints

AddJoining technique has been recently introduced to produce metal-polymer composite hybrid layered structures. The methodology combines the principles of joining and polymeric additive manufacturing. This paper presents three AddJoining process-variants investigated and demonstrated for the material combination aluminum 2024-T3 and acrylonitrile butadiene styrene to form hybrid single lap joints. The microstructure and mechanical performance were assessed. The process variant using heating control showed the ultimate lap shear force of 1.2 +/- 0.05 kN and displacement at a break of 1.21 +/- 0.16 mm as a result of strong bonding formation at the interface of the hybrid joints. For instance, the other two process variants tested (with epoxy adhesive, and with thin-acrylonitrile butadiene styrene (ABS) coating layer applied on the metal) presented reduced mechanical performance in comparison to process variant using heating control, namely approximately 42% and 8.3%, respectively. The former had a mixed adhesive-cohesive failure due to the lower bonding performance between the adhesive and ABS printed layers. The latter displayed a slight decrease in force in comparison to heat-control specimens. This could be explained by the presence of micro-voids formed by solvent evaporation at the ABS coating layer during AddJoining.