Interactions in laser joining of metals to polymers

由于塑料在许多工业部门中的使用越来越多，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。电子工业向着小型化和功能集成化的发展，以及汽车部门使用的材料的特殊轻量化潜力的利用，加强了这一趋势。然而，这种化合物在程序上不容易实现，因为这些材料具有非常不同的物理和机械性能。在这种背景下，平板、牢固结合的化合物尤其难以实现。本研究项目的目的是研究经过物理/化学表面处理的牢固结合、激光连接的塑料-金属复合材料的结合机理和复合材料性能。金属试件将在搭接过程中使用两种不同的配置直接连接到塑料试件，采用直接和间接激光连接工艺。在第一步中，将确定对热连接金属-塑料接头粘接强度的重要影响因素。工艺参数和所获得的结合强度的相关性允许确定所选材料组合的有用工艺窗口。为此，对热接头的失效行为进行了分析和评价。随后，对与等离子处理/涂层有关的结合强度和结合机理进行了检查。此外，还研究了等离子体前处理/涂层对复合材料老化的影响。此外，还将制作具有金属夹层的金属-塑料复合材料，并研究其结合强度和粘接机理。研究了金属过渡层对复合材料时效性能的影响。在建模部分，将使用直接和间接激光拼接过程的热图像和热机械图像来计算局部温度场和热应力。最后，将比较和评估使用等离子预处理/涂层或使用金属中间层的工艺变体。

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.