The tribological performance of nanodiamonds (ND) in aqueous suspensions was investigated via experiments and molecular dynamics (MD) simulations. The results indicated that the introduction of ND significantly improved the naturally poor lubrication ability of water. The best performance was characterized by reductions of 70% and 88% in friction and wear, respectively. The enhancement of the tribological performance was mainly attributed to the ball-bearing effect of the ND. According to the results, the above-mentioned mechanisms would be activated in special condition. Findings determined that the hardness of the counterparts would be a key factor. The rolling motion of the nanodiamond particles was verified by MD simulation. Moreover, results indicated that the lubrication quality of the ND was affected by the sonication process in the nano lubricant preparation.
