Influence of Transfer Film Formation Mechanisms on the Friction and Wear of Polymer Matrix Composites

过去两年的研究表明，二氧化硅纳米颗粒在特定的pv负载范围内形成耐磨膜的能力，克服了传统复合材料在没有纳米填料的情况下不可接受的宏观磨损。此外，我们还观察到，要获得具有理想结构和性能的良好粘附转移膜，一定的表面粗糙度和最小的pv负载是必不可少的。这些粘附良好的转移膜几乎完全由纳米填料制成。我们的假设是，为了获得原位生成保护膜的最佳条件，填料尺寸和反体粗糙度应该具有相似的量级。如果这种考虑是正确的，最佳表面形貌适用于每个填料尺寸。此外，通过在磨合状态下施加更高的负载，可以产生可以在较低负载下使用的保护膜。最后，由于转移膜中几乎没有基质材料，因此这种粘附良好的转移膜的形成机制可能可转移到其他聚合物中。新提案的主要目标是通过实验和数值方法证明这些假设，同时也从根本上研究转移膜的性质，如膜厚度和分布。在实验方法中，将合成尺寸在50、250和1000 nm范围内的二氧化硅颗粒，并将其用于聚合物复合材料中，同时通过激光处理进行适当的表面结构。多模态粒度分布也将被考虑，例如，在一个特定的复合材料中组合50纳米和250纳米大小的颗粒。目标是推导出颗粒大小和表面形貌对最终转移膜形成机制的影响。在第二系列试验中，分别进行了增加和减少pv负载时负载历史试验的影响。目的是利用这些结果在磨合状态下产生粘附良好的传递膜，并在磨合后的稳态状态下产生较低的负载。最后，通过用热塑性基质代替环氧基，研究了迄今为止确定的转移膜形成机制的可转移性。研究结果将对根据需求定制明确的摩擦学性能产生重大影响。摩擦膜形成建模将通过可移动元胞自动机方法进行。自动机的尺寸将在与二氧化硅粒度相同的范围内变化（50至1000 nm，多模态）。负载和对应表面的粗糙度将相应地调整。

Previous studies performed during the last two years revealed the capability of silica nanoparticles towards forming a wear-resistant film at a specific pv-load range which overcomes the unacceptable macroscopic wear of the conventional composite without nanofiller. Furthermore, it was observed that a certain roughness of the counterbody and minimum pv-load is essential for obtaining well adhering transfer films of the desired structure and properties. These well adhering transfer films are made of almost exclusively nanofillers.Our hypothesis is that filler size and counterbody roughness should be of the similar magnitude in order to obtain optimum conditions for in situ generating protecting films. If this consideration is right, an optimum surface topography applies for each filler size. Furthermore, by applying higher loads in the running-in regime, it is possible to generate protecting films that can be used in lower loads afterwards. Finally, due to the fact that almost no matrix material is in transfer film, the formation mechanisms of this well adhering transfer film might be transferable to other polymers. The main goal of the new proposal is to prove these hypotheses by experimental and numerical approaches while also fundamentally investigating transfer film properties such as film thickness and distribution.For the experimental approach, silica particles in the size range 50, 250, and 1000 nm will be synthesized and used in polymer composites, while appropriate surface structuring will be performed by laser treatment. Multimodal particle size distribution will be considered as well, e.g. the combination of 50 nm and 250 nm sized particles in one specific composite. Target is to derive influences of particle size and surface topography on the formation mechanisms of the resultant transfer films. In the second series of tests, the influence of the load history test under both increasing and decreasing pv-loads are conducted. The objective is to utilize the results to create well adhering transfer films in the running-in regime, and for lower loads in the steady-state regime afterwards. Finally, by replacing the epoxy matrix for a thermoplastic matrix, the transferability of the so far identified transfer film formation mechanisms is investigated. The results will have a major impact on customizing well defined tribological properties according to demands.Tribofilm formation modelling will be performed by the movable cellular automata method. The automata size will be varied in the same range as the silica particle size (50 to 1000 nm, multimodal). Loads and the roughness of the counterpart surface will be adjusted accordingly.