20.500.12556/RUL-148685 Superior macro-scale tribological performance of steel contacts based on graphene quantum dots in aqueous glycerol Reducing friction is one of the best ways to lower energy consumption and make processes more environmentally friendly. Because of the growing interest in green lubricants, we investigated the synergetic effects of graphene quantum dots (GQDs) combined with aqueous glycerol to improve the lubrication performance of self-mated steel contacts in reciprocating sliding motion. As a comparison, the lubrication performance of some other two-dimensional (2D) graphitic materials (graphite, graphene oxide, and graphene nanoplatelets) was also studied. The results demonstrate that the GQDs-based nano-lubricant reduces the running-in period and provides super-low friction at a high contact pressure in the boundary-lubrication regime, with 72% and 53% improvements in anti-friction and anti-wear performance compared with aqueous glycerol. On the other hand, the 2D graphitic materials provide super-low friction in the mixed-lubrication regime due to the dominant polishing effect of the hydroxyl groups. The surface Raman mapping indicates that the 2D graphitic materials were severely damaged by the continuous reciprocating motion owing to their inferior crack resistance. In contrast, the superior deformation resistance of the GQDs helps to develop a tough tribofilm. This lubrication mechanism suggests that internal shearing of graphene layers inside the GQDs significantly reduces the wear and friction during the running-in period, while the in-situ formation of strongly adhered tough tribofilm with more surface coverage contributed to the realization of super-low friction under a high contact pressure. This study demonstrated that GQDs-based green nano-lubricants could provide super-low friction at a high contact pressure in the boundary-lubrication regime, which was so far characteristic mainly for conventional environment-polluting lubricants. graphene graphene quantum dots graphite aqueous glycerol super-low friction green tribology grafen grafenske kvantne pike grafit vodni glicerol super nizko trenje zelena tribologija true false true Angleški jezik Slovenski jezik Članek v reviji 2023-08-29 10:27:42 2023-08-29 10:27:44 2024-03-11 12:26:23 0000-00-00 00:00:00 2023 0 0 15 str. Vol. 181, art. 108328 Mar. 2023 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 539.92 1879-2464 10.1016/j.triboint.2023.108328 144799747 1-s2.0-S0301679X23001159-main.pdf 1-s2.0-S0301679X23001159-main.pdf 1 860827BE6A84747DF304F6A89D34F088 f54471ac74249259e09209d3750b68ad2bdd881a53a334b8e1aa8a473f17e2bf 08f6eb7b-4647-11ee-a605-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=172988 https://www.sciencedirect.com/science/article/pii/S0301679X23001159 1 ec315b48-4645-11ee-a605-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=172986 Fakulteta za strojništvo 0 0 0