Improved Wear Resistance and Environmental Adaptability of a Polysiloxane/Molybdenum Disulfide Composite Lubricating Coating Using Polyhedral Oligomeric Silsesquioxane

Polysiloxane/molybdenum disulfide (MoS₂) composite lubricating coatings that are used in low-earth orbit spacecraft have high resistance to atomic oxygen attack and outstanding vacuum tribological properties. However, their atmospheric environment wear resistance and adaptability under high humidity are poor. In this paper, octa-aminophenyl T8-polyhedral oligomeric silsesquioxane (NH₂-POSS) was used to enhance their atmospheric wear resistance and environmental adaptability to increase the protection of polysiloxane lubricating coatings for spacecraft. In this study, the effect of NH₂-POSS on the mechanical properties of a polysiloxane coating and the tribological properties of the POSS-enhanced polysiloxane/MoS₂ lubricating coating were investigated and the mechanism of NH₂-POSS enhancement was discussed. Results showed that the addition of NH₂-POSS markedly improved the hardness and elastic modulus of the polysiloxane coatings by increasing the crosslink density of the polysiloxanes and nanofiller effect of POSS. Among them, 6 wt% NH₂-POSS can reduce the wear rate of the lubricating coating by 25%. In addition, this study also explores the adaptability of polysiloxane/MoS₂ lubricating coatings in a high-humidity environment and an atomic oxygen irradiation environment, which provides a reference for further optimization of polysiloxane lubricating coatings.