Evaluation Of Tribological Properties Of Binder-Free Single-Walled Carbon Nanotube Solids For Solid Lubrication Applications

Binder-free single-walled carbon nanotube (SWCNT) solids were evaluated for solid lubrication applications. The steady-state friction coefficient (p) for the SWCNT solids were found to reach values as low as 0.22-0.24, according to unidirectional sliding friction tests using Si3N4 counterpart in air, which values were slightly higher than that of bulk graphite material ( mu=0.20). SEM and Raman analyses showed that most of SWCNTs that existed in the friction surface transformed into SWCNT-derived transferred film made up of amorphous carbon during sliding. The resultant friction behavior may be related to the smearing of transferred film over the contact area, which was expected to permit easy shear and then help to achieve a lubricating effect during sliding.