In-situ exfoliated graphene for high-performance water-based lubricants

In this study, the tribological behavior of in-situ exfoliated graphene for water-based lubricants is investigated. The aqueous graphene dispersions show high stability due to the assistance of a non-ionic surfactant, Triton X-100. The steel-steel ball-plate tribotest results reveal that the in-situ exfoliated graphene possesses brilliant frictional and anti-wear properties. Compared with pure deionized water, the graphene-enhanced lubricants can offer 81.3% and 61.8% reduction in friction coefficient and wear scar diameter (i.e. a reduction in wear volume by two orders of magnitude), respectively, owing to the formation of a protective graphene layer at the sliding contact zone. The performance of in-situ exfoliated graphene is also better than that of graphene oxide at the same additive concentration. Furthermore, the as-prepared lubricants exhibit enhanced lubrication effect even in high load and diverse velocity cases. It is proposed that the surfactant, Triton X-100, eases the deposition procedure of the graphene layer by adjusting the dispersion wettability of the sliding surfaces, thus leading to the superior tribological properties.