Project Details
Projekt
Coordination Funds
Applicant
Professor Dr.-Ing. Bernd Sauer
Subject Area
Engineering Design, Machine Elements, Product Development
Term
from 2018 to 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 404647253
The majority of tribological systems in technical applications are lubricated with fluids, which are mostly oils and greases. In cases where lubrication with oil or grease is not possible, e.g. in medical technology, in food technology, in production engineering using vacuum processes and in aerospace applications, a solid is often applied to the component surface as an alternative.The lubrication mechanism in solid layers differs fundamentally from tribological systems with fluids; there is, for example, no lubricant circuit of the kind normally found in fluid lubrication. In general, material is transferred from the surface carrying the lubricant to the counterbody, forming transfer layers. During operation of the system, a layer degradation by wear processes takes place continuously, whereby mechanisms for the renewed or continuous build-up of the solid lubricant layer act at the same time. While in the field of sliding movements with lower contact pressures more extensive knowledge with solid lubrication and its functionality is already available, the complex chemical-physical interactions on the surfaces of highly loaded contacts, such as in rolling bearings or gears, have so far only been researched to a limited extent.In this research program, the mechanisms of friction and wear caused by transfer layer formation in tribological systems when lubricated with solid lubricants are to be investigated. For this purpose, system-specific provision processes of the solid lubricant are to be determined as a function of the operating conditions (e.g. temperature, pressure, sliding speeds) in order to be able to guarantee the prerequisites for the availability of solid lubricant in the contact area to be lubricated. Depending on the operating conditions, the lubricant and the contact partners in the highly loaded contact, the transfer processes are to be clarified on this basis. Here, a distinction can be made between physical and chemical transfer processes, which enable a transfer that is as permanent as possible. Physical adhesion mechanisms can be achieved by mechanical "stapling" of solid lubricant components with the surface, chemical mechanisms can be based on physi- and chemisorption. Finally, this understanding is to be used for the synthesis of systems for the provision and suitable transfer of solid lubricants in highly stressed contact areas.The focus of the investigations is on the highly loaded rolling contacts (pressure > 100 MPa). Depending on the lubrication concept, however, it may also be necessary, for example when using a lubricant depot, to include the provision of lubricant from such a less loaded contact in the analysis and modelling in order to adjust the wear of the depot in such a way that sufficient solid lubricant is always available in the highly loaded contact.
DFG Programme
Priority Programmes
