Investigation and Verification of Potential Impacts of Third Body Nanostructure on Tribological Properties of Conventional and Unconventional Material Combinations for Automotive Braking and Risk Assessment of Particle Emission

我们的假设是，在干滑动过程中，光滑的滑动行为和恒定的摩擦水平是由第三体膜形成的颗粒层决定的，第三体膜在盘式制动系统的情况下屏蔽第一主体、衬块和盘。我们详细研究摩擦过程的方法首先是研究第三体膜的纳米结构，其次是通过在纳米尺度上建模来理解这种膜的功能。建模不仅有助于理解摩擦的基本原理，还将提供检查不同微观结构（纳米结构）和应力条件对摩擦行为的影响的机会。第三步和第四步将是通过建模到新的制动片配方中来实施优化过程的结果，并显示修改后的系统可以工作。我们的目标不仅是改善性能，而且还展示了如何替代或消除对环境至关重要的衬垫成分。除了基于铸铁盘的传统汽车制动器外，还将考虑基于陶瓷盘（非传统）的轻质制动器。我们的目的是要证明的假设，该系统的优化方面的光滑的滑动行为和最小的磨损率将导致纳米结构的表面膜和排放的纳米粒子或小团聚体的纳米粒子。因此，我们计划在测功机测试期间进行在线颗粒测量，并在测试程序的某些阶段对排放颗粒进行采样，以进行进一步的纳米级和纳米分析研究。计划在第二阶段对测功机测试期间制动器释放的空气颗粒进行风险评估项目。BAM目前已为该企业设置了两个重要的先决条件：i）准备参考材料和活细胞纳米毒理学研究的体外测试程序，以及ii）构建具有空气传播纳米颗粒的细胞培养物暴露系统。

Our hypothesis is that smooth sliding behaviour and a constant friction level during dry sliding is determined by the formation of a granular layer from third body films which are screening the first bodies, pad and disc in case of a disc brake system. Our method to study friction processes in detail is firstly to investigate the nanostructure of third body films and secondly to understand the function of such films by modelling on the nanometre scale. Modelling will not only help to understand the fundamentals of friction but will also provide the opportunity to check the impact of different microstructures (nanostructures) and stressing conditions on the friction behaviour. The third and fourth steps will be to implement results of an optimization process done by modelling into new brake pad formulations and show that the modified system works. The goal is not only to improve properties, but also to show how environmentally critical pad ingredients can be substituted or eliminated. Besides conventional automotive brakes, based on cast iron discs, light weight brakes based on ceramic discs (unconventional) will be considered as well. Our intention is to prove the hypothesis that optimization of the system with respect to smooth sliding behaviour and minimal wear rate will result in nanostructured surface films and the emission of either single nanoparticles or small agglomerates of nanoparticles. Therefore we have planned to perform on-line particle measurements during dynamometer tests and sampling of emitted particles during certain stages of a test procedure for further nanoscopic and nanoanalytical investigations.Risk assessment of airborne particles released from brakes during dynamometer tests is planned for a second period of the project. Two important prerequisites for this enterprise are currently installed at BAM: i) preparation of a reference material and in vitro test procedure for nanotoxicological studies with living cells, and ii) construction of an exposure system for cell cultures with airborne nanoparticles.