MoS2 Lubricating Film Meets Supramolecular Gel: A Novel Composite Lubricating System for Space Applications.

In the field of space mechanical lubrication, to improve the reliability and life of space lubrication, solid lubricating film-liquid lubricant composite lubrication has been used in recent years. This lubrication method can improve the durability of sliding friction mating surfaces, reduce equipment wear, and extend the service life of motion mechanisms. However, due to unstable factors such as volatilization and creeping of liquid lubricants in microgravity and ultra-high-vacuum environments, the solid lubricating film wears out after long-term use and produces wear debris and other unfavorable factors. To solve the above problems, this study proposes a novel composite lubrication system constituting a MoS2 film in combination with a supramolecular gel. The tribological performance of this lubrication system establishes an extended service life with a lower wear rate compared to the MoS2 film, regardless of functioning in vacuum or atmospheric conditions. More importantly, the results of the irradiation experiment demonstrate that MoS2-gel exhibits better anticreep performance as compared to MoS2-oil when exposed to atomic oxygen and ultraviolet light for 4 h. The analysis of this composite lubrication mechanism also reveals the formation of a continuous transfer film on the surface of the friction pairs by virtue of the outstanding synergistic effect between the MoS2 film and the gel. MoS2 debris is present in the gel as an additive, and the gel is capable of replenishing automatically once the MoS2 film is depleted. Moreover, the strong anticreep properties of the gel are attributable to the multialkylated cyclopentane oil being trapped by the intricate reassembling of the gelator network. It is firmly believed that this novel MoS2-gel composite lubrication system may have good prospective applications in space and special machinery domains.