Study of run-in behaviour of laser-patterned surfaces underdry sliding conditions

该提案的主要目标是检查和了解激光纹理化表面在第一次滑动循环中关于形貌和微观结构的演变，以定制摩擦和磨损性能。定义明确的表面形貌将通过激光干涉冶金（LIMET）创建。与使用顺序激光纹理化工艺可实现的那些相比，该技术允许在一个加工步骤中以相关工程规模的横向特征尺寸生产高度受控的表面特征。传统技术表面的特征在于随机粗糙度分布，其难以整体描述。与此相反，LIMET允许精确定义的模型表面的可重复形成，从而克服了随机粗糙度的情况，这是该项目的主要优势之一。首先，将仔细检查与激光图案化基板摩擦的扁平球。在下一步中，计数器主体也将被激光图案化，并且详细研究相互对准的作用和所得图案的横向特征尺寸。在这种情况下，将对技术相关的材料（镍、钨、钛）进行测试，这些材料都具有不同的晶体结构。此外，该项目还将研究晶粒结构（准单晶和柱状生长的多晶样品）的影响。此外，实验数据将作为输入参数，用于与伦敦帝国理工学院伦敦直接合作（A.V. Olver教授，D. Dini和S. Medina）。我们在伦敦的合作伙伴提出的研究解决了表面相互作用的一些方面，这些方面在真实的粗糙表面的接触分析中通常被忽视，特别是两个表面的粗糙度的相互作用及其与法向切向载荷相互依赖性的关系以及外部载荷机制的影响。虽然在不考虑这些问题的情况下，接触建模已经取得了很大进展，目前可以很好地预测载荷应力和接触条件，现在有必要将这些细节引入建模系统，以达到摩擦和磨损的基本和预测建模所需的复杂程度。通过高分辨率技术制作的标本与我们在伦敦的科学合作伙伴最近开发的模型相结合，将导致对干滑动下相互作用的接触表面的更深入的理解。此外，激光图案的微观结构退化将被广泛研究，这可以直接与模型相关。最后，所获得的结果将适用于其他材料和日益重要的纳米接触。

The main goal of this proposal is to examine and to understand the evolution of laser textured surfaces, regarding topography and microstructure, in the very first sliding cycles in order to tailor friction and wear properties. The well-defined surface topographies will be created by laser interference metallurgy (LIMET). This technique allows for the production of highly controlled surface features in one processing step with lateral feature sizes on relevant engineering scales compared to those achievable using sequential laser texturing processes. Conventional technical surfaces are characterized by a stochastic roughness distribution which is difficult to describe in its entirety. In contrast to that, LIMET permits the reproducible formation of precisely-defined model surfaces and thus overcomes the stochastic roughness situation which is one of the major benefits within the project. First of all, a flat ball rubbing against a laser-patterned substrate will be scrutinized. In a next step, also the counter body will be laser-patterned and the role of mutual alignment and the lateral features sizes of the resulting pattern studied in detail. In this context, tests will be performed on technologically relevant materials (Ni, W, Ti), all having different crystal structures. Furthermore, the influence of grain structure (quasi-single crystalline and columnar-grown polycrystalline samples) will be investigated within the project.In addition, the experimental data will be used as input parameters for modelling the surfaces and microstructural evolutions in a direct collaboration with the Imperial College London (Prof. A.V. Olver, Dr. D. Dini and Dr. S. Medina). The research proposed by our collaboration partners in London addresses some aspects of surface interaction that are commonly neglected in contact analysis of real rough surfaces, specifically the interaction of the roughness of both surfaces and its relationships with normal-tangential loading interdependency and the influences of external loading mechanisms. Whilst much progress has been made in contact modelling without consideration of these subjects, currently allowing good prediction of loading stresses and contact conditions, it has now become necessary to introduce such details into the modelling system in order to reach the level of sophistication needed for fundamental and predictive modelling of friction and wear.The possibility to generate well-defined surface and the subsequent characterisation of the as-fabricated specimens by high resolution techniques combined with recently developed models by our scientific partners in London will lead to an enhanced understanding of interacting contact surfaces under dry sliding. Moreover, the microstructural degradation of the laser pattern will be extensively studied which can be directly correlated with the models. Finally, the gained results will be applicable to other materials and increasingly important nanoscale contacts.