The synthesis of two-dimensional MoS₂ nanosheets with enhanced tribological properties as oil additives

The use of MoS₂ nanosheets as oil additives has been proved effective to reduce friction and wear. Furthermore, it has been suggested that the synthesis of MoS₂ nanosheets with an ultrathin structure could benefit the friction and wear reduction, as they would penetrate into the contact area easily. In this paper, two-dimensional MoS₂ nanosheets were successfully fabricated by a solvothermal method with the aid of oleylamine. Meanwhile, the synthesized MoS₂ nanosheets exhibited perfect dispersing stability in paraffin oil, due to the surface modification by oleylamine molecules. The friction and wear properties of the synthesized MoS₂ nanosheets as oil additives were investigated using a ball-on-disk tribotester. The results showed that the two-dimensional MoS₂ nanosheets exhibited enhanced friction-reducing and antiwear behaviors as compared to the multilayered MoS₂ nanosheets. The prominent tribological performance of the two-dimensional MoS₂ nanosheets was attributed to the formation of a thick tribofilm inside the wear tracks, which was confirmed by XPS analyses of the rubbing interfaces.