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

在工业化国家，运输在产生废气排放方面起着重要作用，废气排放除了燃烧燃料外，还造成轮胎和制动系统部件的磨损。迄今为止相对较少考虑的摩擦学系统是乘用车的制动系统，对制动粉尘排放到环境中有很大贡献。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，它们也受到严重磨损。颗粒增强铝基复合材料（amc）的应用主要是为了大大减少制动盘和刹车片的磨损。在机动车辆上大规模使用这种制动系统仍然是不可能的，因为一方面，基本的摩擦学关系了解得很少。另一方面，在amc上产生功能表面（摩擦表面）的合适的精加工工艺是缺失的。因此，该项目的主要目标是更深入地了解由制动盘和刹车片组成的摩擦学系统中的相互作用。在这种情况下，由于制动盘的特定精加工以及制动盘的预处理而产生的表面特性要考虑在内。最后，应了解在相关加载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起来。一个重要的研究目标是创造一个基本无损伤和适当的表面生成的应用于制动盘摩擦表面的amc的知识。摩擦学研究的重点在于表面性能、预调节（摩擦膜的控制生产）以及磨合和磨损行为之间的基本作用机制。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，这样锋利的边缘颗粒就会稍微凸出基体。通过在车削过程中叠加超声振动作为第二种方法，在精加工过程中直接产生相应的微边缘，而不需要后续的加工步骤。通过光学和触觉方法对各自的表面进行详细表征，并通过微观结构解析方法对表面层进行表征。开姆尼茨工业大学（Chemnitz University of Technology）在实验室规模上获得的结果将转移到制动盘组件的工业合作伙伴那里，并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.