%0 Generic
%A Brizuela, M.
%A García-Luis, A.
%A Oñate, J. I.
%A Garmendia, I.
%T Tribolab: 												An experiment on space tribology. In-orbit data at the ISS
%J European Space Agency, (Special Publication) ESA SP
%D 2009
%@ 0379-6566
%U https://hdl.handle.net/11556/1759
%X In February 2008, the Discovery Shuttle mission ST-122 brought the European Columbus Space Laboratory to the International Space Station (ISS). One of the Columbus External Payload Facilities (CEPA) is occupied by the European Technological Exposure Facility (EuTEF), a group of seven different scientific experiments, where the tribology experiment Tribolab is located. The TriboLAB instrument is a space tribometer which performs tests with different lubricants and different devices at basic and component level respectively: pin-on-disk and ball bearing. TriboLAB allows to investigate the tribological behavior of lubricants under conditions not possible to simulate simultaneously on earth: g-0, vacuum, microvibrations, LEO radiation, etc. It is interesting to point out that previously obtained tribological data on Earth (friction coefficients, friction torques and long term durability of the lubricant thin layers) are going to be compared to the results obtained in the microgravity conditions of the LEO orbit of the ISS. In this way, a correlation between both data series is going to be done and the effect of the severe conditions that the lubricant has to withstand on the space is going to be evaluated. Up to now, these data are not available and the mechanisms designers will benefit from the knowledge obtained in this experiment for their future designs, as lubricants play a key role in the deployment of mechanisms and structures. Previous works by the authors have shown that the WC alloyed MoSx coating shows better tribological properties than conventional MoS2 coating, both under vacuum and under air at higher humidity conditions [1,2]. This work reports on the results of the pin-on-disk tests on the alloyed MoSx coatings in orbit in comparison with the results obtained under laboratory conditions on ground. These tests have shown that the solid lubricating film maintain very low friction levels of 0.04 and reach a maximum of 1,011,000 wear cycles demonstrating a similar behavior to that experienced on ground.
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