Changes in the composition, structure and friction property of sputtered MoS 2 films by LEO environment exposure

Xiaoming Gao, Ming Hu, Jiayi Sun, Yanlong Fu, Jun Yang, Weimin Liu, Lijun Weng

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Radio frequency-sputtered MoS 2 films had been exposed for 43.5 h in real low earth orbit (LEO) space environment by a space environment exposure device (SEED) aboard China Shenzhou-7 manned spaceship. The composition, morphology, phase structure and friction property of the exposed films were investigated using X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray energy-dispersive spectroscopy (EDS) and ball-on-disk tribometer. XRD and EDS results revealed that the as-deposited MoS 2 films were characterized by a MoS x O y phase structure, in which x and y values were determined to be ∼0.65 and 1.24, respectively. XPS analysis revealed that due to space atomic oxygen attack, the film surface was oxidized to MoO 3 and MoS x O y with higher O concentration, while the partial S was lost. However, the affected depth was restricted within the surface layer because of protective function of the oxidation layer. As a result, the friction coefficient only exhibited a slight increase at initial stage of sliding friction.

Original languageEnglish
Pages (from-to)30-38
Number of pages9
JournalApplied Surface Science
Volume330
DOIs
StatePublished - 1 Mar 2015
Externally publishedYes

Keywords

  • Atomic oxygen
  • LEO
  • MoS films

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