Synthesis of ionic liquid decorated muti-walled carbon nanotubes as the favorable water-based lubricant additives

Ionic liquid decorated muti-walled carbon nanotubes (MWCNTs-IL) were prepared by amidation, and their tribological property as a kind of water-based additives was investigated under four-ball mode. The MWCNTs-IL exhibited the best friction-reducing and antiwear performance at optimal additive concentration of 0.015 wt% and the load of 40 N. Under these conditions, the friction coefficient and wear volume of base liquid reduced by 42 and 72%, respectively. The obvious friction-reducing and outstanding antiwear properties of MWCNTs-IL could be attributed to the synergistic lubrication effect of ionic liquid groups and carbon nanotubes. The ionic liquid groups not only endowed the MWCNTs-IL with good dispersion stability in base liquid, but also resulted in the preferable embedded stability of MWCNTs-IL between the rubbing surfaces by electrostatic interactions. Then the friction and wear of the rubbing surfaces were greatly reduced owing to the nanolubrication effects of MWCNTs (such as polishing, mending and rolling effects).