20.500.12556/RUL-175988 Macroscale superlubricity with a high load-carrying capacity enabled by nitrogen-doped graphene quantum dots in lubricated silicon-doped amorphous carbon films Achieving macroscale superlubricity with engineering materials is highly desirable for energy conservation, environmental benefits, and longevity of mechanical components. However, attaining superlubricity in aqueous-lubricated systems with enhanced load-bearing capacity remains challenging in metallic materials. Herein, nitrogen-doped graphene quantum dots (NGQDs) as a nano-additive in aqueous glycerol facilitate macroscale superlubricity between friction pairs of steel and silicon-doped hydrogenated amorphous carbon (a-C:H:Si). Superlubricity is observed in boundary-lubrication regime with a friction coefficient of 0.0055–0.0097 under various sliding conditions. Notably, the wear of the steel counterface (k = 8.51 × 10−9 mm3/Nm) decreased by 47.8%, resulting in a final contact pressure of 206.7 MPa, which exceeds values reported for aqueous-lubricated systems during superlubricity. The lubrication mechanism reveals that NGQDs' adsorption on the steel-worn surface, coupled with the tribocatalytic generation of FeNxCy moieties on a-C:H:Si surface, is crucial for reducing friction. These FeNxCy moieties, with a multitude of active sites, facilitate the subsequent anionic adsorption of pyrrolic-rich NGQDs. Simultaneously, the formation of amorphous graphitic film, driven by continuous shearing and exfoliation of graphene sheets within the adsorbed NGQDs, contributes to the stability of superlubricity. These findings provide insights into the functional characteristics of NGQDs for achieving superlubricity in aqueous-lubricated systems, paving the way for future energy-saving applications. macroscale superlubricity metallic materials streel supemazljivost kovinski materiali jeklo true false false Angleški jezik Slovenski jezik Članek v reviji 2025-11-17 11:53:06 2025-11-17 11:53:11 2026-01-12 12:22:02 0000-00-00 00:00:00 2025 0 0 21 str. iss. 7, art. 2400671 Vol. 6 May 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 620.1/.2 2688-4062 10.1002/sstr.202400671 236432131 RAZ_Nadeem_Irfan_2025.pdf RAZ_Nadeem_Irfan_2025.pdf 1 1950A8E318DD20086F36DF701027B7E2 418f62d2b8c8a30acbe180fb9c2ed9bd6cbba4045650cde7c0466673bd26e129 9b045e0b-c3a5-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=221992 https://www.sv-jme.eu/?ns_articles_pdf=/ns_articles/files/ojs30/1368/68f8d8ba2df46.pdf&id=7499 0 44a7d77c-c3a3-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=221990 Fakulteta za strojništvo 0 0 0