Effects of multi-walled fullerene-like particles on tribological properties of a-C:H DLCs under boundary lubrication

Abstract

Suitable friction modifiers and anti-wear additives for hydrogenated amorphas carbon (a-C:H) films have been investigated by many research groups for a decade since it is well-known that the combination of the a-C:H film and the conventional additives hardly exhibits good tribological performances under boundary lubrication. In this study, to confirm the effectiveness of nano-carbon additives for improving the tribological performance of a-C:H films, the tribological performances of the combination of the a-C:H film and multi-walled fullerenes (MWFs) containing oil was investigated under boundary lubrication. Especially, we compared the effects of the MWFs on the tribological performances of two DLCs: a-C:H and tetrahedral amorphous carbon (ta-C) using a ball-on disk tribometer and in-contact Raman tribometer that can monitor the chemical structure of frictional interfaces. All our results suggest that the combination of a-C:Hs and MWFs exhibits an ultralow friction and remarkable wear reduction compared to non-MWF added oils due to the formation of MWF tribofilms uniformly at the frictional interfaces.

Keywords

• diamond-like carbon
• multi-walled fullerenes
• boundary lubrication
• friction modifier
• anti-wear additive