265 / 2021-04-20 15:32:21

Molecular design of epoxy-functionalized polysiloxanes and tribological properties of the polysiloxane/MoS2 lubricating coating for low-earth orbit environment

epoxy-functionalized polysiloxane,lubricating coating,Tribological properties,atomic oxygen resistance

Polysiloxanes have been widely used in spacecraft due to their excellent atomic oxygen (AO) resistance. However, the low adhesion and mechanical strength of polysiloxane coatings limit their application on moving parts. In this paper, a series epoxy-functionalized polysiloxanes with different R/Si value were synthesized. The lubricating coatings were prepared by adding MoS₂ to the polysiloxanes. The tribological properties of the polysiloxane/MoS₂ lubricating coatings were investigated. Meanwhile, the effects of AO irradiation on the micro-structure and tribological properties were thoroughly studied. Results show that wear life of the polysiloxane lubricating coatings is related to the R/Si value and epoxy group of the polysiloxanes resin. And the prepared epoxy-functionalized polysiloxane lubricating coatings exhibited better tribological properties under vacuum condition due to the synergistic effect of low surface energy polysiloxane and MoS₂ during vacuum friction. The polysiloxane coating achieved excellent AO resistance ascribe to the generation of SiO₂ protective layer. The thickness of SiO₂ layer was only 60 nm, which has no effect on the vacuum tribological properties of the polysiloxanes lubricating coating. After AO irradiation, the polysiloxane lubricating coating maintained a low friction coefficient and excellent wear resistance under the vacuum condition.