Generation and Preconditioning of Aluminium Matrix Composite Friction Surfaces of Braking Discs

在工业化国家，交通运输在产生排放方面发挥着重要作用，除了轮胎和制动系统部件磨损造成的燃料燃烧外，还造成排放。迄今为止，相对较少考虑的摩擦学系统是客车汽车的制动系统，其显著地促进了制动粉尘排放到环境中。目前，绝大多数汽车都使用铸铁制成的制动盘。然而，除了刹车片外，它们也会受到严重的磨损。颗粒增强铝基复合材料（AMC）的应用尤其旨在显著降低刹车盘和刹车片的磨损。在机动车辆中大规模使用这种制动系统仍然是不可能的，因为一方面，基本的摩擦学关系知之甚少。另一方面，缺少在AMC处生成功能表面（摩擦表面）的合适的精加工工艺。因此，该项目的主要目标是更深入地了解由制动盘和制动片组成的摩擦学系统中的相互作用。在这种情况下，应考虑制动盘的特定精加工以及制动盘的预处理所产生的表面特性。最后，应了解在相关载荷制度下发生的磨损机制。这只能通过跨学科的研究方法来实现，将材料和生产工程工作结合在一起。一个重要的研究目标是创造知识，使AMC在很大程度上无损伤，并适合作为制动盘摩擦表面的应用。摩擦学研究的重点在于表面性能之间的基本作用机制、预处理（摩擦学薄膜的受控生产）以及其磨合和磨损行为。对于预处理，垂直于制动运动方向的微边缘被认为是有利的。一种方法是将基体合金去除几微米，使得边缘锋利的颗粒从基体中略微突出。作为第二种方法，通过在车削中叠加超声振动，在精加工期间直接产生相应的微边缘，而无需后续工艺步骤。通过光学和触觉方法以及通过微观结构解析方法的表面层来详细表征各个表面。在切姆尼茨理工大学实验室规模上获得的结果将转移到部件制动盘的工业合作伙伴，并在那里根据制动系统规定的测试程序进行全面测试。

In the industrialised countries, transport plays a significant role in the generation of emissions, which result in addition to the combustion of the fuel from the abrasion of tires and brake system components. A hitherto comparatively little considered tribological system are the braking systems of passenger cars, contributing significantly to brake dust emissions into the environment. Currently, brake discs made of cast iron are used in the vast majority of cars. However, in addition to the brake pads they are subject to significant wear.The application of particle-reinforced aluminium matrix composites (AMCs) is intended in particular to considerably reduce the wear of both the brake disc and the brake pad. A large-scale use of such a braking system in motor vehicles is still not possible, since on the one hand, basic tribological relationships are poorly understood. On the other hand, suitable finishing processes for the generation of functional surfaces (friction surfaces) at the AMCs are missing. The primary goal of the project is therefore to gain a deeper understanding of the interactions in the tribological system consisting of the brake disc and the brake pad. In this case, the surface properties resulting from the specific finishing of the brake discs as well as a preconditioning of the brake discs are to be taken into account. In the end, the wear mechanisms occurring in relevant loading regimes shall be understood. This can only be achieved through an interdisciplinary research approach, uniting material and production engineering work.An important research goal is the creation of knowledge for a largely damage-free and appropriate surface generation of AMCs for the application as a brake disc friction surface. The focus of the tribological investigations lies on fundamental mechanisms of action between the surface properties, a preconditioning (controlled production of tribological films), as well as its running-in and wear behaviour. For preconditioning, micro-edges that are perpendicular to the direction of the braking motion are considered favourable. One approach is to remove the matrix alloy by just a few microns so that the sharp-edged particles protrude slightly out of the matrix. By superimposing an ultrasonic vibration in turning as a second approach, corresponding micro-edges are to be produced directly during finish machining without a subsequent process step. The respective surfaces are characterised in detail by optical and tactile methods as well as the surface layers by means of microstructure resolving methods. The results obtained on a laboratory scale at Chemnitz University of Technology are to be transferred to the industrial partner on the component brake disc and tested there comprehensively according to the test procedures prescribed for the braking system.