Tribological performances of SiO_2/graphene combinations as water-based lubricant additives for magnesium alloy rolling

摘要

The tribological performances and rolling lubrication properties of SiO2/graphene combinations as water-based lubricant additives were evaluated using a reciprocating ball-on-plate tribometer and two-high rolling mill. The results obtained therein revealed that dispersion of the SiO2/graphene combinations in water is conducive to the reduction of the friction coefficient and wear volume and the increase in the load-bearing capacity, which were superior to the results obtained for the graphene nanofluids or SiO2 nanofluids separately. In the best case, the addition of 0.1 wt% nano-SiO2 mixed with 0.4 wt% graphene in water reduced the friction coefficient by 48.5% and the wear volume by 79% compared with the addition of 0.5 wt% graphene. Transmission electron microscopy images of the SiO2/graphene combinations additives after friction testing showed that nano-SiO2 supports the graphene layers as pillars and prevent assembly between the graphene layers. The synergistic effect of the components considerably enhanced the SiO2/graphene combination. Additionally, the preliminary application of the SiO2/graphene combination nanofluids in magnesium alloy rolling effectively decreased the rolling force and improved the surface quality of sheets.