Dry-running screw machines without synchronization gears have improved efficiencies as a result of the minimal profile gap area and, due to the lack of oil, are a sustainable and resource-saving alternative to the conventional liquid-lubricated design. The flexibly adjustable surface pressure represents a possibility of conditioning the dry rolling contact, but control of friction and wear is essential in order to achieve the longest possible operation time for the screw rotors. The friction is reduced by the application of special MoSx thin layers. In addition, the addition of modification elements and the setting of the parameters of the tribological load spectrum lead to an improvement in friction and wear. On the rotor test bench, the functionality of selected MoSx(:X) thin films is evaluated under real operating conditions in the sliding rolling contact between the screw rotors. The project aims to macroscopically and microscopically understand friction and wear mechanisms of MoSx(:X) solid lubricants in real contact situations of screw rotors and to develop strategies to increase the operation time of the solid lubricant. The contact load between the screw rotors is prescribed on the rotor test bench via an adjustable surface pressure (from 100 to 1000 MPa), an externally specified temperature (up to approx. 150 °C) that varies along the rotors, the load duration and the ambient atmosphere (air or just nitrogen).
This project is funded by German Research Foundation and is being carried out in cooperation with institutions Lehrstuhl für Werkstofftechnologie and Experimentelle Physik 2 of the TU Dortmund University.