Enhanced tribological properties in core–shell structured SiO2@GO hybrid fillers for epoxy nanocomposites

SiO2 coated with graphene oxide (GO) hybrids (SiO2@GO) were fabricated by electrostatic self-assembly and introduced into an epoxy polymer (EP) matrix to prepare epoxy composites by a solvent-free curing process. The thermal stability, mechanical properties and tribological behavior of SiO2@GO/EP composites were investigated and compared. It was found that the epoxy composites with the aligned core–shell structure of SiO2@GO improved the thermal stability, as well as excellent mechanical and tribological properties. The low content 0.5 wt% SiO2@GO/EP nanocomposites exhibited nearly 88.4% reduction in the friction coefficient and several orders of magnitude reduction in wear rate, constituting a potential breakthrough for future tribological applications. Compared with unfilled epoxy polymers or epoxy polymers with unmodified fillers, the major increase in the tribological properties of the SiO2@GO/EP composites shows the synergy effect between nano-SiO2 and GO during the wear process. The behavior of nano-SiO2 and GO were probably mostly due to ball-bearing and an ultrathin lamellar effect, respectively. The obtained results indicate that the core–shell structure of SiO2@GO as a more effective synergistic system is a valid method for greatly improving the friction and wear properties and mechanical properties of resin-based composites.