Comparative Study of Tribological Properties of Modified and Non-modified Graphene-Oil Nanofluids under Heated and Non-heated Conditions

Abstract

With the aim of achieving more effective friction and wear reduction in sliding bearing applications, surface-modified graphene, which exhibits better dispersion stability than non-modified graphene, was synthesized and applied in this study using various graphene allotropes, including graphene nanoplatelets (GNP), multiwalled carbon nanotubes (MWCNT) and nanostructured graphite (NSG). Friction and wear tests of each type of graphene allotrope under modified and non-modified conditions were studied using a pin-on-ring tribo tester. In addition, the dynamic viscosity of each synthesized nanofluid sample was measured using a falling-ball viscometer. A series of modified graphene-oil nanofluids and non-modified graphene-oil nanofluids were prepared and heated before their friction and wear performance was investigated at room temperature. Friction and wear behavior, as well as the dynamic viscosity of the heated nanofluids vary insignificantly when compared to those of the non-heated nanofluids. The results showed that the best friction and wear reduction was achieved by modified GNP with friction and wear reduction of 60.5% and 99.4%, respectively.