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- PublicaciónSTABILITY AND TRIBOLOGICAL PERFORMANCE OF NANOSTRUCTURED 2D TURBOSTRATIC GRAPHITE AND FUNCTIONALISED GRAPHENE AS LOW-VISCOSITY OIL ADDITIVES(LUBRICANTS, 2023)GUILHERME OLIVEIRA NEVESTHE DISPERSION STABILITY OF CARBON-BASED SOLID LUBRICANTS/LUBRICATING OILS REMAINS A CHALLENGE TO OVERCOME. RECENTLY, NOVEL PROCESSING ROUTES WERE DEVELOPED TO OBTAIN 2D TURBOSTRATIC GRAPHITE PARTICLES VIA SOLID-STATE REACTIONS BETWEEN B4C AND CR3C2 (GBC) AND BETWEEN SIC AND FE (GSF) THAT PRESENT OUTSTANDING TRIBOLOGICAL PROPERTIES IN A DRY SCENARIO, AS WELL AS FUNCTIONALIZED GRAPHENE (GNH). THIS WORK INVESTIGATED THE SUSPENSION STABILITY OF GBC AND GSF PARTICLES (0.05 WT.%) DISPERSED IN A LOW-VISCOSITY POLYOL ESTER LUBRICATING OIL AND THEIR TRIBOLOGICAL PERFORMANCE. AMMONIA-FUNCTIONALIZED GRAPHENE (GNH) PARTICLES WERE ALSO USED AS A REFERENCE. IN ORDER TO EVALUATE THE DISPERSION STABILITY, IN ADDITION TO THE CLASSICAL DIGITAL IMAGE TECHNIQUE, A MUCH MORE ASSERTIVE, RELIABLE, QUANTITATIVE AND RARELY REPORTED IN THE LITERATURE TECHNIQUE WAS USED, I.E., THE STEPTM (SPACE AND TIME-RESOLVED EXTINCTION PROFILES) TECHNOLOGY. RECIPROCATING SPHERE-ON-FLAT TRIBOLOGICAL TESTS WERE CARRIED OUT, IN WHICH BEFORE CONTACT, 0.2 ?L OF PURE OIL AND SUSPENSION (POE + 0.05 WT.% OF SOLID LUBRICANT) WAS APPLIED ON A FLAT SURFACE. THE RESULTS SHOWED THAT THE GBC PARTICLES REMAINED REMARKABLY STABLE AND REDUCED THE SPHERE WEAR RATE BY 61.8%. FROM THE TRIBOSYSTEM POINT OF VIEW, THE PRESENCE OF GBC AND GSF REDUCED THE WEAR RATE BY 18.4% AND 2.2%, RESPECTIVELY, WITH RESPECT TO THE PURE OIL, WHILE THE GNH PARTICLES INCREASED THE WEAR RATE BY 4.2%. FURTHERMORE, THE WEAR RATE WAS IMPROVED DUE TO THE HIGHLY DISORDERED CARBON TRIBOLAYER FORMATION IDENTIFIED ON BOTH SURFACES.