An investigation on the lubrication mechanism of MoS₂ nano sheet in point contact: The manner of particle entering the contact area

The goal of the work is to investigate the lubrication mechanism of MoS₂ nano sheet. Polyisobutyleneamine Succinimide (PIBS) provides the steric repulsion to disperse nanoparticles in oil due to its long carbon chain. In the present study, the tribological behavior of nano-MoS₂ sheet mixed with different percentages of PIBS was explored. The dispersed state and the mode of nano-MoS₂ sheet entering the contact point were studied. Ball-on-disk results illustrated that the COF of nano-MoS₂ in paraffin oil with free of PIBS was 26.2% compared with those containing 3 wt% PIBS, and the reduction of wear depth reached 41.9%. The nano-MoS₂ sheets with 3 wt% PIBS were in discrete state in paraffin oil, which moved with side flow and could not enter the contact area to cause poor lubrication. Aggregation of particles took place in the case of low PIBS concentration and without PIBS, it entered the contact area and formed well-distributed MoS₂ tribofilm to reduce friction and wear.