Influence of transfer- and transformation processes on service life of dry lubricated ball bearings

固体或干式润滑剂应用于许多技术系统，在这些系统中，由于环境条件(如真空、高温、卫生法规)而不能使用油或润滑脂等常规润滑剂。典型的应用是无流体润滑的滚动轴承。对于它们的功能来说，在整个使用寿命内提供充足的润滑油是必不可少的。在特定材料优化的滚动轴承保持架的帮助下，与传统的MoS2涂层套圈相比，可以显著提高轴承的使用寿命。使用过程中消耗的干润滑剂对耐用性至关重要。过去已经开发了计算使用寿命的模型。然而，对于干润滑球轴承的真正技术设计来说，他们已经接近极限了。在干式润滑剂转移的物理模型和系统描述方面尤其如此。因此，到目前为止，不可能可靠地预测由于转移润滑而延长的使用寿命。该项目的重点是改进的使用寿命模型，以更深入地了解干式润滑轴承系统涉及的复杂物理和技术过程。现代的表面和薄膜分析方法，如电子显微镜、电子光谱和质谱学技术将是实现这一目标的主要工具。它能够对轴承表面的摩擦应力进行精确和定量的分析，为高级使用寿命模型提供必要的经验输入数据。其中，针对所涉及的润滑材料的每个元素测量了以下数量：摩擦系数、摩擦能磨损系数和传递系数。为此，将在真空中使用具有不同转速和载荷的四轴承试验台进行摩擦学试验。固体润滑轴承的多体系统模型将用于分析轴承中的机械载荷谱。除考虑材料转移外，还考虑了摩擦学诱导的化学反应引起的干式润滑剂的转变过程。此外，将寻求新的方法来理解负荷集体对仍由经验确定的输入值的影响。

Solid- or dry lubricants are applied in a number of technical systems, where conventional lubricants, such as oil or grease, could not be used because of environmental conditions (i.e. vacuum, high temperature, hygiene regulations). Typical applications are fluid-free lubricated rolling bearings. For their function, a sufficient lubricant supply over the complete service life is indispensable. With the help of material-specific optimized rolling bearing cages, consisting of a polymer-compound with embedded dry lubricant, it is possible to improve service life significantly in comparison to bearings with conventional MoS2-coated rings. The consumption of dry lubricant during use is essential for the durability. Models have been developed in the past to calculate the duration of service life. However, for the real technical design of dry lubricated ball bearings they approach their limits. This is the case in particular with regard to the physical modelling and the systematic description of dry lubricant transfer. So far, therefore, it is not possible to predict reliably the extension of the service life due to transfer - lubrication. The project focuses on an improved service life model to achieve a deeper knowledge of the complex physical and technological processes involved in dry lubricated bearing systems. Modern methods of surface- and thin film analysis, such as electron microscopy, electron-spectroscopic and mass-spectrometric techniques will be the main tools to reach this objective. It enables precise and quantitative analysis of tribologically stressed bearing surfaces providing the necessary empirical input data for an advanced service life model. Among others, the following quantities are measured with respect to each element of the lubricant materials involved: Friction coefficient, friction energy-wear-factor and transfer – factor. For this purpose tribological tests will be conducted in vacuum using a four-bearing test bench with different rotational speeds and loads. Multi-body system models for solid lubricated bearings will be used for the analysis of the mechanical load spectrum in the bearings. Besides the material-transfer, transformation processes of the dry lubricant due to tribological induced chemical reactions will be taken into consideration. Furthermore, new approaches will be pursued to understand the influence of load collectives on the still empirically determined input values.