Controlling of the friction in lubricated systems through Multi-Scale texturing with laser interference texturing and micro coining

定制的表面图案可以减少润滑的机器部件中的摩擦和磨损，从而提高效率和使用寿命，并减少润滑油消耗。这种结构的形状、大小和间距对每个摩擦学系统都是特定的，这阻碍了任何关于最佳参数的一般性声明。在第一个资助期，结构是通过激光干涉、微压花和它们的组合(多尺度结构)在平面上产生的，并用实验室摩擦轰炸机进行了表征。研究表明，在流体动力或混合润滑条件下，具有十字图案的激光毛化表面与边界或混合润滑状态下的半球形浮雕结构一样，可延长润滑膜寿命并减少磨损。除了摩擦接触外，表面结构还可用于接触外部，将润滑剂输送到接触区或防止其离开接触。对于高压应用，这样可以保护细小的结构，避免润滑不足。初步研究表明，这种织构(特别是多尺度结构)特别影响润湿和扩散行为，并允许控制被动润滑剂的输送。考虑到初步研究，研究建议的目标可以定义为：1.将所获得的关于使用多尺度结构的平面知识和已证实的增强应用于具有曲面圆柱面的应用(即滑动轴承)。研究作为温度梯度函数的表面结构(激光、浮雕和多尺度)对润滑剂被动输送的影响，以及研究结果的应用(即滚动元件轴承)。从这个意义上讲，将设计和测试构造圆柱形表面的试验装置。将进行模拟以解释和分析成形过程。所制备的样品的表面，即滑动轴承的轴套，将进行表面形貌(形状和粗糙度)和微观结构(扫描电子显微镜、电子背散射光谱、透射电子显微镜)表征。样品的摩擦学检查将在亚琛大学(RWTH)IME的服务合同下进行。为了研究被动润滑剂的传输，将在平坦的纹理表面进行模拟和基本实验，以验证模型并确定结构的候选名单。然后，有希望的结构将被应用于机械元件并进行摩擦学检查。

A tailored surface pattern can reduce friction and wear in lubricated machine parts and thus lead to increased efficiency and service life and reduced lubricant consumption. The shape, size and spacing of such a structure are specific to each tribological system, hindering any generalised statement as to optimal parameters.In the first funding period structures were produced on flat surfaces by means of laser interference, micro-embossing and a combination thereof (multiscale structuring) and characterised with a lab tribometer. The investigations show that under hydrodynamic or mixed lubrication, laser-textured surfaces with a cross pattern increase the lubrication film lifespan and reduce wear, as do hemispheric embossed structures in boundary or mixed lubrication regime.In addition to tribocontacts, surface structures can also be used outside of the contact, to carry lubricant to the contact zone or to prevent it from leaving the contact. For applications with high pressures the fine structures would thus be protected and deficient lubrication could be avoided. Preliminary studies showed that such textures (especially multiscale) specifically affect the wetting and spreading behaviour and allow the control of passive lubricant transport.Taking into account the preliminary investigations, the objectives of the research proposal can be defined as:1. Transference of the acquired knowledge and the proven enhancements in planar surfaces concerning the use of multiscale structures to an application with curved cylindrical surfaces (i.e. plain bearings).2. Investigation of the influence of surface structures (laser, embossed and multiscale) on the passive transport of lubricant as a result of surface topography, as a function of a temperature gradient, as well as the application of the findings (i.e. rolling-element bearings).In this sense, test set-ups to structure cylindrical surfaces will be designed and tested. Simulations will be performed to interpret and analyse of the forming process. The surface of the prepared samples, i.e. the shaft sleeve of a plain bearing, will be topographically (shape and roughness) and microstructurally (SEM, EBSD, TEM) characterised. The tribological examination of the samples will be under a service contract at the IME at Aachen University (RWTH).For the investigation of the passive lubricant transport, simulations and basic experiments will be conducted on flat textured surfaces to validate the model and determine a shortlist of structures. Promising structures will then be applied to a machine element and tribologically examined.