Tribological study on preparation of two- dimensional MoS2 as grease additive by ultrasonic liquid phase stripping

MoS2 nanosheets with different sizes were prepared by ultrasonic liquid phase stripping and used as additives in lithium grease. The morphology, composition and structure of MoS2 nanosheets were characterized by electron microscopy, Raman spectroscopy, X-ray diffractometer and thermogravimetric analyzer; the tribological properties of lithium MoS2 grease were investigated by using four-ball friction and wear testing machine. The wear surface morphology of steel ball under MoS2 grease lubrication was analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, and the lubrication mechanism of MoS2 grease was preliminarily explored. The results show that MoS2 nanosheets show excellent wear resistance and friction reduction performance. When the diameter of the added sheet is 80 nm and the amount is 1.0%(mass fraction), the tribological performance of lithium grease is the best, the maximum no-bite load and sintering load are increased by 55.4% and 61.2% respectively compared with the base grease, and the friction coefficient is decreased by 23.15%. The maximum diameter of wear scar diameter is decreased by 21.13%.The improvement of its tribological properties is mainly related to the tribological protective film composed of various oxides of Fe, FeOOH, MoS2 and related organic matter.

Automated summary

MoS2 nanosheets with different sizes were prepared and used as additives in lithium grease. The morphology, composition, and structure of the nanosheets were characterized and the tribological properties of the grease were investigated. The results showed that MoS2 nanosheets exhibited excellent wear resistance and friction reduction performance. The improvement in tribological properties was attributed to the formation of a protective film composed of various oxides of Fe, FeOOH, MoS2, and related organic matter.