Effect of temperature on the friction and wear properties of graphene nano-platelets as lubricant additive on Al-25Si alloy

The development in automotive field requires a new class of lubricant additive that can be environment friendly and stands against wear and reduce the energy dissipation by enhancing friction properties. The present study reports the friction and wear behaviour of polyalphaolefin base oil with and without the addition of 0.5 wt% graphene nano-platelets. The formulations were tested on hypereutectic Al-25Si alloy against steel ball under dry and lubricated conditions. Tribological tests were conducted from room temperature to 250 degrees C with an applied load of 5 N at 100 rpm. The normal load was varied from 5-20 N at 200 degrees C and also, sliding distance tests were carried out upto 1000 m in step of 250 m at 200 degrees C with an applied load of 5 N. Coefficient of friction and wear rate were significantly reduced due to the adsorption of GNP between the tribopair. Moreover, the results noticeably prove that GNP particles in PAO oil easily form protective tribofilm to prevent the direct contact between the tribopair surfaces.