Interactions in laser joining of metals to polymers

由于塑料在许多工业部门的使用越来越多，以及对轻质结构的需求增加，金属和塑料的连接变得越来越重要。这一趋势得到了电气行业小型化和功能集成化的发展以及汽车行业所用材料的特定轻量化潜力的利用的加强。然而，由于材料具有非常不同的物理和机械性能，因此这种化合物在程序上不容易实现。在这种情况下，平坦的，牢固结合的化合物是特别难以实现的。这是本研究项目的目的，调查牢固结合，激光束连接塑料-金属复合材料进行物理/化学表面预处理的粘合机制和复合材料的性能。金属样本将通过在搭接过程中使用两种不同的配置直接连接到塑料样本，使用直接和间接激光束连接工艺。在第一步中，将确定对热连接的金属-塑料接头的粘结强度的显著影响因素。工艺参数和所获得的粘结强度的相关性允许为所选材料组合确定有用的工艺窗口。为此，热接头的失效行为进行了分析和评估。随后，结合强度和粘附机制的检查进行等离子体预处理/涂层。此外，等离子体预处理/涂层对复合材料的老化的影响进行了研究。此外，金属-塑料复合材料与金属夹层将生产和检查有关的粘结强度和粘附机制。金属中间层对复合材料老化的影响也将被研究。在与建模有关的部分中，将使用直接和间接激光束连接过程的热和热机械图像来计算局部温度场以及热致应力。最后，将比较和评估具有等离子体预处理/涂层或具有金属夹层的工艺变体。

The joining of metals and plastics becomes more and more important due to the increasing use of plastics in many industrial sectors and an increased demand for lightweight structures. This trend is reinforced by a development towards miniaturization and functional integration in the electrical industry as well as by the utilization of specific lightweight potentials of materials that are used in the automotive sector. Such compounds are, however, procedurally not easy to realize as the materials have very different physical and mechanical properties. Within this context, flat, firmly bonded compounds are especially difficult to realize.It is the aim of this research project to investigate the adhesion mechanisms and composite properties of firmly bonded, laser beam joined plastic-metal composites that were subjected to physical / chemical surface pre-treatments. The metallic specimens will be directly joined to the plastic specimen by using two different configurations in a lap joint procedure, utilizing direct as well as indirect laser beam joining processes. In a first step, significant influencing factors on the bond strength of thermally joined metal-plastic joints will be determined. The correlation of the process parameters and the obtained bond strengths allows the determination of useful process windows for selected material combinations. For this purpose, the failure behavior of thermal joints is analyzed and evaluated. Subsequently, an examination of the bonding strength and adhesion mechanisms is conducted in relation to the plasma pretreatment /coating. Additionally, the influence of the plasma pretreatment /coating on the aging of the composite is investigated. Furthermore, metal-plastic composites with metallic interlayers will be produced and examined concerning their bond strength and adhesion mechanisms. The influence of the metallic interlayers on the aging of the composite will be investigated as well. In the part that is concerned with modeling, the thermal and thermo-mechanical images of the direct and indirect laser beam joining processes will be used to calculate the local temperature fields as well as the thermally induced stresses. Finally, the process variants with a plasma pretreatment / coating or with metallic interlayers will be compared and evaluated.