For high current carrying plug-in connections, which are used in electrical power supply and in electrical transportation, silver or silver alloys are almost exclusively used as coating materials in order to combine low frictional wear with the lowest electrical contact resistance. In electrically powered vehicles, the charging connectors must withstand thousands or tens of thousands of charging cycles during their service life. Also the environmental conditions differ strongly. However, the use of lubricants, such as those commonly used for switchgears in electrical power supply, is ruled out due to the untrained users, the problematic dosage, and the transfer to possibly unsuitable contact partners. Silver dispersion coatings, in which particles with lubricating properties are embedded, are considered as an alternative.
This publication therefore compares self-lubricating silver dispersion coatings (Ag-C, Ag-WS2) to lubricated and unlubricated coatings. These were already evaluated electrically and mechanically in preliminary tests on model geometries. Subsequent tests on industrial test specimens serve to qualify the various self-lubricating coatings for use. Heating tests as well as friction wear tests under current load and without current load are performed. Finally, the self-lubricating coatings are compared.