Influence of multilayer structuring morphology on the characteristics of self-propagation reaction in hybrid joining

• Applicants: Professor Dr.-Ing. Jean Pierre Bergmann; Professor Dr.-Ing. Frank Mücklich
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials ; Joining and Separation Technology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426339810

Hybrid plastic-metal composites are steadily increasing in use and application, but also require further development of joining technologies to meet chemical and physical material properties. Based on previous work, the use of reactive multilayers and their self-propagating high temperature synthesis reaction has proven to be a particularly promising joining method in this regard. If the used multilayers can be specifically opened in advance or during the reaction process itself, molten plastic caused by the reaction can penetrate this separation layer and form a strong composite bond with the metal partner. In the proposed follow-up project, the joining of plastic and metal by means of reactive Al/Ni multilayers will be investigated systematically in order to achieve an optimized material throughput and thus maximum bond strength. The aim is to analyze and derive the interactions between both process-related and self-introduced foil structures as well as the surface characteristics introduced into the metal. The specific project aim is to derive tailored reaction profiles in the composite by influencing the surface structure of the metal partner as well as the structure of the reactive multilayer itself. Different laser-based ablation processes are used to structure the metal surface, enabling different surface structures in terms of both geometric shape and structure density. The occurring forms of oxidation and redeposition and their influence on the bond are considered specifically. For the structuring of multilayers by means of ultrashort pulsed laser, previous own results are the basis for further research. The aim is to derive foil structures that create a desired heat release distribution by guiding the reaction front while ensuring maximum material flow. By developing a new joining device, it will be possible to characterize the reaction process in the composite in-situ and to derive influences from the reaction process and the joining partners themselves. The main focus is on the inspection of the reaction orthogonal to the foil plane in the plastic-metal composite system using transparent plastic materials and an optical transparent force initiation system. In addition, this allows to identify the temperature-time characteristics in the overall composite. Supporting numerical analyses will be performed by developing a macroscopic 2D/3D FE-model setup that represents the time-temperature behavior of the reactive multilayer foil in the plastic-metal composite.

• DFG Programme: Research Grants