Thermal dependence of the wear of molybdenum disulphide coatings

Molybdenum disulphide (MoS2) is a common constituent for vacuum and space solid lubricant coatings because of its low friction, vacuum compatibility, and insensitivity to radiation effects. In this study the effects of temperature on the tribological properties of a low wear MoS2 coating was examined. Three temperatures were analyzed, ‘cold’ (−100 °C), ‘ambient’ (22 °C), and ‘hot’ (100 °C). It was found that for all three temperatures the friction coefficient remained below μ = 0.02 and was athermal, but the wear of the coating decreased with decreasing temperature. Under the cold temperature conditions the volume of material removed was reduced by approximately half as compared to the ambient and elevated temperature experiments. Characterization of the debris was done using an environmental scanning electron microscope in conjunction with energy dispersive spectroscopy. It was found that at the lower temperatures the debris size was smaller (i.e. finer) than at the higher temperatures. As the temperature regime increased, the range of debris size increased.