Deposition of the system Mo-N-(Ag) by using highly-ionized PVD methods and its investigation with regard to high performance wear protection and electrical sliding contact

• Applicants: Dr. Martin Fenker; Professor Dr. Frank Schmidl
• Subject Area: Coating and Surface Technology
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 354352022

With the constraint of energy efficiency, materials are forced to the border of resilience. The combination of high temperature and mechanical wear for example is a heavy-duty mechanical process. Diamond-like carbon (DLC) coatings are of limited suitability for this application. Coatings on the basis of Mo-N seem to be more promising. Additionally, the system Mo-N-(Ag) which will be developed within the project, has certain relevance as coating material for electrical sliding contacts for the industrial sector of German electrical power industry. These coatings have the potential to fulfill the requirements with respect to power density for the electrical power supply.High performance wear protecting coatings made from Mo-N or from the less studied system Mo-N-Ag, respectively, show low friction coefficients due to the formation of the lamellar MoO3 phase, Magnéli phases or Ag molybdate phases. For the first time three different PVD techniques - dc magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS) and pulsed laser deposition (PLD) - are utilized in parallel for the synthesis of those coatings. These techniques differ drastically with respect to the ionization degree of the sputtered species and to the ionization/dissociation degree of the N2 gas. The coating properties of the system Mo-N-(Ag) can be tailored by the control of the plasma conditions. The essential scientific-technological goals are the demanding deposition of stoichiometric Mo-N coatings, the development of new high performance Mo-N-(Ag) coatings by alloying with silver and the optimization of appropriate electrical and mechanical-tribological properties.Finally, a systematic understanding of the performance of the coating systems will be achieved by acquiring the plasma and coatings properties and by correlating them with each other. The obtained results will serve for the setting up of an empirical model for the tribological and electrical behavior of Mo-N-Ag coatings. The project will deliver an important contribution to the question of how much ionization in combination with kinetic energy do we need for the film-forming species to tailor selectively coating properties like for example to be able to control the stoichiometry of Mo-N.

• DFG Programme: Research Grants