Superior wear resistance of epoxy composite with highly dispersed graphene spheres

Graphene has been proved to have an obvious superiority in suppression of the wear of polymers. However, the wide industrial application was suppressed by the bad graphene dispersion and complex preparation procedure. In this work, we employed carbon spheres coated with dispersed graphene (graphene spheres, g-AM) as filler to prepare the epoxy composites with direct mixing and curing. Comparing with neat epoxy and composites filled with calcined carbon spheres (CM, without graphene), the thermal and tribological properties of g-AM/EP composites were improved when the g-AM content was low. When chemical functionalization by grafting epoxy chain on the graphene (E–g-AM) was conducted, the total performance, especially the wear resistance, was remarkably improved even at high graphene content. The wear rate of E–g-AM/EP composites was reduced by 95% at 20 wt.% E–g-AM, compared to pure cured epoxy resin. This superior wear resistance was related to the synergistic effect of carbon spheres and graphene. Carbon spheres improved shore hardness and flexural strength, thus reducing the wear rate. The graphene had the high dispersion and good interface adhesion with epoxy, leading to the excellent lubricating effect and the improved mechanical and thermal performance of the composites. Graphical abstract: Graphene spheres with high dispersion state were firstly used as fillers of epoxy and made the composite excellent wear resistance.[Figure not available: see fulltext.].