Practical Evaluation of Ionic Liquids for Application as Lubricants in Cleanrooms and under Vacuum Conditions

Abstract

As part of a publicly funded cooperation project, novel high-performance lubricants (oils, greases, assembly pastes) based on ionic liquids and with the addition of specific micro- or nanoparticles are to be developed, which are adapted in their formulation for use in applications where their negligible vapor pressure plays an important role. These lubricants are urgently needed for applications in cleanrooms and high vacuum (e.g., pharmaceuticals, aerospace, chip manufacturing), especially when the frequently used perfluoropolyethers (PFPE) are no longer available due to a potential restriction of per- and polyfluoroalkyl substances (PFAS) due to European chemical legislation. Until now, there has been a lack of suitable laboratory testing technology to develop such innovative lubricants for extreme niche applications economically. There is a large gap in the tribological test chain between model testing, for example in the so-called spiral orbit tribometer (SOT) or ball-on-disk test in a high-frequency, linear-oscillation test machine (SRV-Tribometer from German “Schwing-Reib-Verschleiß-Tribometer”), and overall component testing at major space agencies (ESA—European Space Agency, NASA—National Aeronautics and Space Administration) or their service providers like the European Space Tribology Laboratory (ESTL) in Manchester. A further aim of the project was therefore to develop an application-orientated and economical testing methodology and testing technology for the scientifically precise evaluation and verifiability of the effect of ionic liquids on tribological systems in cleanrooms and under high vacuum conditions. The newly developed test rig is the focus of this publication. It forms the basis for all further investigations.