MoS2: Foundations for improved service life calculations for solid-lubricated rolling bearings in a vacuum based on multiscale investigations
In many technical applications, conventional lubricants such as oils and greases are unsuitable due to operating conditions like vacuum or strict requirements regarding cleanliness and contamination control. In such cases, solid lubricants, especially molybdenum disulfide (MoS₂), represent an alternative, although their tribological behavior has so far not been sufficiently understood.
The objective of the project is the development of a microstructure- and mechanism-based model for predicting the service-life of MoS₂-lubricated rolling bearings. To achieve this, the Chair of Engineering Design and CAD at the University of Bayreuth collaborates with the Chair of Mechanical Behavior of Materials at the University of Kassel and the Computer Chemistry Center at FAU Erlangen-Nuremberg. By combining PVD coating processes, experimental characterization methods, and simulation-based approaches, friction and wear mechanisms are investigated from the macro- to the nanoscale.
The main focus lies on tribologically induced microstructural changes such as reorientation of the coating texture, material removal and transfer, and the formation of transfer films. Furthermore, the influence of intrinsic material properties as well as external load and contact conditions on wear behavior and the usable lubricant volume is analyzed. The insights gained will be used to extend an existing service life model for solid-lubricated rolling bearings, which will be experimentally validated in the later stages of the project.
The project is part of the DFG Priority Programme SPP 2074 and contributes to a deeper understanding of the relationships between microstructure evolution and the tribological behavior of solid lubricant coatings.
Methodology for the multiscale analysis of structural changes in MoS₂ coatings under tribological loading in rolling contact: (a) MoS₂-coated disk with wear track after tribological testing in a twin-disk tribometer, (b) scanning electron microscopy (SEM) image of the wear track, in which a lamella was cut by ion beam milling, (c) preparation and extraction of the cut lamella for investigation in a transmission electron microscope (TEM), (d) high-resolution TEM image of the basal-oriented microstructure of MoS₂, (e) model structure of MoS₂ for ab initio molecular dynamics simulations.
Contact: Christian Orgeldinger