Einfluss von unterschiedlich erzeugten Verschleißschutzschichten auf das Dauerschwingverhalten ausgewählter Werkstoffe und deren Verbesserung

一般来说，磨损损伤的过程可以很好地估计，但叠加的机械载荷和高温会对涂层部件的寿命产生灾难性的影响。例如，滚动力可以产生高循环轴承压力。同时，剪切应力在地表以下几毫米处产生最大值。由于这些压缩和剪切应力的循环特性，需要设计和测试耐磨涂层的高循环疲劳性能。此外，还必须考虑温度的影响。摩擦学系统要求表面具有合适的微观结构，可以在高温下实现高磨损和抗疲劳。进一步决定寿命的因素是所应用服务负载的性质和大小。单个涂层系统在轴向或弯曲载荷下的表现必须通过一系列测试来研究，这些测试是在准静态和循环载荷下作为温度的函数。还必须分析衬底/涂层或基体/硬质合金相之间的界面形态的程度。该项目将包括保护基材免受干磨料磨损的MMC涂层。颗粒增强铁、镍、钴基合金可提高磨料耐磨性。通过将合适几何形状的硬金属颗粒嵌入相对柔软的基体中并垂直对准表面来实现磨损保护。然而，这种特殊的组织形态可能对裂纹形核和裂纹扩展产生不利影响。在高压载荷下，硬相和硬相与基体之间的界面可能成为裂纹成核的部位。在多大程度上可能发生这种疲劳进展，以及在多大程度上可能导致多层系统过早失效，将进行研究。在剧烈磨损的情况下，基体必须足够坚固，以支持嵌入的硬质金属颗粒抵抗施加的力，并防止涂层脆性失效。热处理将用于优化耐磨和抗疲劳性能。这一目标可以通过析出分散的碳化物的二次硬化来实现。精确调整的热处理增加了基体的强度，从而也增加了疲劳强度，但除此之外，还可以改善嵌入的硬质合金颗粒的支撑。然而，强度的增加往往导致延展性的丧失。本项目的研究活动旨在将材料和材料系统性能结合起来，从而优化磨损和HCF性能。所要求的热处理必须考虑到基体的微观结构变化。为了在这些遭受磨损和疲劳载荷的部件的制造中实现经济的过程，必须详细阐述综合的工艺步骤。

Whereas in general, the progress of wear damage can be quite well estimated, superposed mechanical loading and high temperatures can have catastrophic effects on the life time of coated components. For example, high cyclic bearing pressures can result from rolling forces. At the same time, shear stresses are induced with maximum values located some millimeters below the surface. Because of the cyclic nature of these compressive and shear stresses, the wear resistant coatings need to be designed and tested with regard to high cycle fatigue performance. In addition, the influence of temperature has to be taken into account. Tribological systems require surfaces with suitable microstructures that can achieve both high wear and fatigue resistances at high temperatures. Further life-determining factors are the nature and magnitude of the applied service loads. How the individual coating systems behave under axial or bending loads must be investigated by test series under quasi-static and cyclic loading as a function of temperature. The degree to which the interface morphology between substrate/coating or matrix/hardmetal phase must also be analyzed.This project will include MMC coatings that protect the substrate against dry abrasive wear. The abrasive wear resistance will be enhanced by particle reinforced Fe, Ni and Co base alloys. The wear protection is realized by hard metal particles of suitable geometry being embedded in the relatively soft matrix and vertically aligned to the surface. However, this particular structural morphology may detrimentally affect crack nucleation and crack propagation. At high pressure loads, the hard phases and the interfaces between the hard phase and the matrix may become crack nucleation sites. To what extent such fatigue progress may occur and to what extent this may contribute to premature failure of the multilayer system will be investigate.In case of intensive wear situations, the matrix must be strong enough to support the embedded hardmetal particles against the applied forces and to prevent brittle failure of the coating. Heat treatments will be performed for optimizing wear and fatigue resistances. This target can be realized by secondary hardening due to the precipitation of finely dispersed carbides. A precisely tuned heat treatment increases the strength of the matrix and thereby also the fatigue strength but in addition, can lead to an improved support of the embedded hardmetal particles.The increase in strength, however, often results in a loss of ductility. The research activities in this project aim to combine the material and material system properties in such a way that wear as well as HCF performance are optimized. The required heat treatments must take into account the microstructure changes of the substrate. In order to realize economic processes in the manufacturing of these components that are subjected to wear and fatigue loading, integrative process steps must be elaborated.