Synergistic tribological performance of a water based lubricant using graphene oxide and alumina hybrid nanoparticles as additives

Graphene oxide (GO) and alumina (Al 2 O 3 ) nanoparticles were added in deionized water in order to synthesise a dimensionally integrated nanolubricant. Tribological tests were performed using an alloy/stainless steel contact pair. A 0.12 wt% 1:1 GO-Al 2 O 3 lubricant produced 64% and 47% reductions in the COF as well as 63% and 60% improvements in the Ra compared with 0.06 wt% Al 2 O 3 and 0.06 wt% GO solutions. Analysis of the worn surface indicated that a thin film consisting of a layer of GO and a tribo-layer of Al 2 O 3 was formed during testing. The GO layer prevented the direct contact of surface asperities, leading to a low resistance to sliding, whilst the Al 2 O 3 tribo-layer acted as a load bearer to strengthen the GO layer.