Tribo-thermo-electrical investigation on lubricating grease enriched with graphene nano-platelets as an additive

Many efforts are being made in recent years to boost the performance of traditional lubricants with innovative nano-additive, like graphene. In this paper long-term lubricated pin-on-disc tests were performed with four grease compounds filled with 0.5 %–5 % graphene nano-platelets. Severe contact conditions were explored to investigate the impact of graphene on the performance and thermal properties of grease. The temperature of the sliding contact and the in-situ electric contact resistance were monitored and correlated to friction and wear. Results of the tribo-thermo-electrical tests indicated that a moderate quantity of graphene reduce both friction and wear because graphene strengthened the lubricating film against scuffing. However, an excessive quantity was detrimental and interfered with lubrication. Graphene also affected the thermal properties of grease, but it did not directly affect the overall thermal behaviour of the tribopair.