References of "Koch, Marcus"
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See detailFailure mechanism analysis based on laser-based surface treatments for aluminum-polyamide laser joining
Amne Elahi, Mahdi UL; Koch, Marcus; Bardon, Julien et al

in Journal of Materials Processing Technology (2021), 298

The development of strong metal to polymer assemblies is currently an important research subject thanks to its prominence to develop lightweight structures. Furthermore, laser welding is known to be a ... [more ▼]

The development of strong metal to polymer assemblies is currently an important research subject thanks to its prominence to develop lightweight structures. Furthermore, laser welding is known to be a fast, reliable, and versatile joining process, and it was demonstrated recently that it can be applied to such metal to polymer systems. To enhance the mechanical properties of the laser-joined aluminum-polyamide (Al-PA) specimens, laser polishing and laser ablation processes have been implemented on the aluminum surface before joining. The polyamide surface was also treated with the laser beam, separately. The surfaces were tested by several characterization techniques before and after each surface treatment. Then aluminum and polyamide samples with different surface treatments have been joined with an identical laser joining process. The mechanical properties of the joints in single lap shear configuration are reported and the failure mechanisms are discussed based on micro-computed x-ray tomography imaging of joined specimens and microscopic analysis before failure. Results show that both surface treatments of aluminum significantly improve the shear load of the joint; however, with different failure mechanisms. Polyamide surface treatment and increasing degree of crystallinity are effective when combined with the laser polishing of the Al surface. This combination is responsible for further enhancement of the shear load of the joint to the limit of base metal strength which is approximately 60 % improvement compared to the untreated samples. Finally, energy dispersive X-ray mapping shows the physicochemical bonding between aluminum oxide and polyamide at the interface. [less ▲]

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See detailEVALUATION OF THE JOINT BASED ON DIFFERENT SURFACE CONDITIONS FOR ALUMINUM-POLYAMIDE LASER WELDING
Amne Elahi, Mahdi UL; Koch, Marcus; Plapper, Peter UL

in Journal of Laser Applications (2021)

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface ... [more ▼]

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface treatment of the metal has a decisive effect on the joint quality and thus on the mechanical properties. In the present study, different mechanical and laser-based surface treatments have been investigated to develop diverse surface conditions on aluminum. Abrasive blasting and laser ablation were used to increase the surface roughness, while abrasive polishing and laser polishing were applied to minimize the surface roughness. In contrast to abrasive surface treatments, laser-based ones were implemented to create artificial oxide layers on the aluminum surface. The surface structures of pretreated samples have been studied with scanning electron microscopy and roughness test. The laser welding of pretreated aluminum with polyamide was achieved with the heat conduction joining technique. To enlarge the welding area and control the heat input, spatial and temporal modulations of the laser beam were implemented. Finally, a single lap tensile-shear test, microscopic analysis of fractured surfaces, and welding cross sections were employed to evaluate the joints. Results show that the presence of an artificial aluminum oxide layer and low roughness are essential to achieve a superior joint between aluminum and polyamide (improvement of approximately 58% in the shear load of the joint compared to as-received welded samples). The cross section of the superior joint which is the laser-polished aluminum welded to polyamide is studied with transmission electron microscopy. [less ▲]

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See detailPre and post-treatments to improve weldability and mechanical properties of Aluminum-Polyamide laser welded specimens
Amne Elahi, Mahdi UL; Koch, Marcus; Heck, Mike et al

in Procedia CIRP (2020), 94

The laser polishing surface treatment is a prerequisite for enhanced weldability that is enabled by superior adhesion between the weldments. The paper describes the laser polishing process of the aluminum ... [more ▼]

The laser polishing surface treatment is a prerequisite for enhanced weldability that is enabled by superior adhesion between the weldments. The paper describes the laser polishing process of the aluminum surface to develop a relatively thick and porous artificial aluminum oxide layer. Microscopic observation shows the laser polishing process significantly improves the adhesion of molten polyamide to the aluminum surface. Besides, the shear load of the pretreated joints is much higher than that of as-received ones. However, for the majority of the welded samples, the failure happens at the polyamide near the interface of aluminum/polyamide due to the thermal effect and structural changes of polyamide during the welding process. By applying the post-treatment of the welded specimens with different cycles, the mentioned failure mechanism is not observed anymore. Therefore, the mechanical properties of the joint will be improved and reach to the limits of the base materials. [less ▲]

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See detailLaser polishing of Aluminum and Polyamide for dissimilar laser welded assemblies
Amne Elahi, Mahdi UL; Koch, Marcus; Plapper, Peter UL

Scientific Conference (2019, June 27)

Detailed reference viewed: 117 (5 UL)