Research on tribological behaviour and interfacial characteristic of Polyimide-MoS2 composite under cryogenic-vacuum environment

Tribological behaviour of Polyimide (PI)-MoS2 composite, pure PI, sputtering MoS2 film is investigated under RTvacuum and cryogenic-vacuum through in-situ methods, i.e., X-ray photoelectron spectrum (XPS), X-Ray Diffraction (XRD), residual gas analyzer (RGA). Cryogenic causes an increase of friction coefficient (friction coefficient) of PI-MoS2 and pure PI, while it is inverse for sputtering MoS2 film. The friction interface is influenced by enriched water under cryogenic, and the possible mechanism is intermolecular hydrogen bonds caused by water restrict the formation of high oriented shear layer. Due to MoS2 film is not as sensitive as PI to moisture, oxidation at friction interface is relaxed because of cryogenic, which leads to a better friction behavior. Cryogenic causes compressive stress at the interface between PI matrix and MoS2 particles, which results in high friction coefficient due to the difficulty in release of the latter and breakage in some regions in where PI covers MoS2. Local cryogenic environment complicates the investigation in which the only purpose is to study the effect of cryogenic-vacuum on tribological properties of some lubricants.

Automated summary

The tribological behavior of Polyimide (PI)-MoS2 composite, pure PI, and sputtering MoS2 film under RTvacuum and cryogenic-vacuum was investigated. Low temperature increased the friction coefficient of PI-MoS2 and pure PI, while it had the opposite effect on sputtering MoS2 film. The friction interface was influenced by water under cryogenic conditions, leading to the formation of intermolecular hydrogen bonds that restricted the formation of highly oriented shear layers.