Tribological properties of Ni-based self-lubricating composites with addition of silver and molybdenum disulfide

Tribological properties of Ni-based composites containing silver and molybdenum disulfide were studied from room temperature to 700 °C. The composites were prepared by powder metallurgy technique and the phase composition and microstructure were addressed according to the characterization by SEM and XRD. The results show that the composites were composed of Ni, Cr2O3, Ag and CrxSy phases after sintering. The best tribological properties were obtained when the silver and molybdenum disulfide contents were 20 wt% and 8.5 wt%, respectively. The tribo-chemical reaction occurred between Ag and Mo oxide during the rubbing process, which led to the formation of silver molybdate lubricating film. The improved tribological properties were attributed to the formation of silver molybdate lubricating tribolayers.

► Nickel-base composites were prepared by mechanical alloying and sintering.
► The friction coefficient and wear rate decrease with the increasing of Ag contents.
► The reaction between Ag and Mo oxide forms silver molybdates lubricating film.
► The improved tribological properties are attributed to the molybdates tribo-layers.