Tribological properties of dispersed carbon nanotubes in lubricant

This study examined the tribological properties of two lubricating oils, mobil gear 627 and paraffinic mineral oils, with multi-walled carbon nanotubes (MWCNTs) nanoparticles used as additives with various concentrations (0.1, 0.5, 1, and 2 wt.%). The friction and wear experiments were performed using a four ball tribotester. The samples were tested for their anti-wear, load carrying capacity, and friction coefficients according to ASTM D-2783, ASTM D-2596, and ASTM D-5183 standards. The experimental results show that the addition of MWCNTs to base oils exhibit good friction reduction and anti-wear properties. The wear test results show a decreased wear by 68% and 39% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. Furthermore, the friction reduction results show a decrease of friction about 57% and 49% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. The weld load of the base oil containing 1% MWCNTs was found to be 400 kgf and 125 kgf as compared with base mobil gear 627 and paraffinic mineral oils, respectively, which got welded at 200 kgf and 100 kgf. The morphologies and typical element distribution of the worn surfaces were characterized by scanning electron microscope (SEM) and energy-dispersive X-ray (EDX). The SEM micrographs and EDX chemical analysis confirm the formation of a tribolayer composed of the elements from the nanoparticles.