Two-dimension layered nanomaterial as lubricant additives: Covalent organic frameworks beyond oxide graphene and reduced oxide graphene

Abstract

Two-dimension graphene-like covalent-organic frameworks (GCF) nano-sheets were successfully fabricated to evaluate the tribological behavior as lubricant additive in comparison to GO and rGO in PAO 10 oil. The exploration shows that conjugate system of GCF brings p-d feedback coordination to metal ions created by exoelectron, promoting the formation and stability of adsorbed film. The mechanical strength of covalent bond structure in-plane ensures carrying capacity and durability, and the ultrathin layered feature reduces shear stress due to slide effect. Eventually, the excellent reducing friction (up to 53.5%) and anti-wear (up to 95.4%) were achieved at an ultralow dosage of 0.008 wt%. By contrast, dissociation of C–O linkages of rGO and GO induced by tribo-stress and tribo-heat deteriorates its stability and durability.