Preparation of graphene‐loading copper nanoparticles by freeze drying and its tribological properties

To reduce the agglomeration of graphene and improve the synergistic friction‐reducing and anti‐wear action of graphene loading copper, one‐step preparation of reduced graphene oxide/copper(RGO/Cu) nanoparticles by freeze‐drying method was used, the influence of process parameters on particles size of RGO/Cu is studied by orthogonal experiments. The microstructures of RGO/Cu nanoparticles are characterized by SEM and AFM, and the tribological properties of RGO/Cu nanoparticles are studied on a tribometer. The results show that the purity of RGO/Cu nanoparticles prepared by freeze‐drying was higher, and the copper nanoparticles 100–200 nm are uniformly attached to the graphene surface. It was found that RGO/Cu nanoparticles have better friction reduction and anti‐wear properties than graphene mono‐agent as lubricant additive. The synergistic anti‐friction and anti‐wear performance are better at the addition of 0.10 wt% for RGO/Cu nanoparticles. Compared with the base oil, the friction coefficient decreases by 23.1%, and the width of wear scar decreases by 62.5%.