Tribological behaviors of graphene oxide partly substituted with nano-SiO₂ as lubricant additives in water for magnesium alloy/steel interfaces

Although graphene oxide (GO) has emerged as an excellent lubricant additive in water, there remain great challenges in their practical application due to high production costs. By taking into account the low cost and also its excellent tribological properties, it is likely that nano-SiO₂ can be used as a lubricant additive to partially replace GO. Hence, this paper aims to explore the tribological properties of nano-SiO₂ incorporated in GO nanofluids for partial GO replacement by investigating the friction coefficient and wear volume of the prepared SiO₂/GO hybrid nanofluids for magnesium alloy/steel sliding pairs. The experiments reveal that the SiO₂/GO hybrids retain low friction coefficients as compared to individual GO or SiO₂ at all test conditions in this study. However, as for the bearing capacity test, all samples can provide a low wear volume under the loads of 1 and 3 N. With the increase of the normal load, there is considerable differences in the anti-wear behavior. Compared with that of individual GO nanofluids, the wear volume of the GO/SiO₂ (mass ratio of 0.3:0.2) hybrid nanofluids was reduced by 50.5% at 5 N and by 49.2% at 8 N. Furthermore, the wear volume of the GO/SiO₂ (mass ratio of 0.3:0.2) hybrid nanofluids was reduced by 46.3% under the rigorous conditions, as compared to individual GO nanofluids. The findings provide new insights into developing carbon nanomaterial-based hybrid nanofluids for magnesium alloy formation.