Tuning Autoxidation and Friction of Mineral Oil by Fullerene Cluster Properties

Lubricant oils can autoxidize due to contact with air. This reaction is accelerated by heat and can be catalyzed with metal ion impurities. Therefore, new antioxidant additives are needed. Carbon nanomaterials exhibit excellent thermal oxidation resistance and can act as additives for lubricant oils to extend their operation lifetime. In this work, we studied the autoxidation behavior of a mixture of C 60 clusters in mineral oil (MO) containing different amounts of toluene during mixing. The C 60 powder also contains C 70 molecules, and with the presence of toluene during mixing the ratio of C 60 /C 70 was increased. The oil-fullerene mixtures were heated at 150 o C for 48 h under magnetic stirring. FTIR analysis shows that the initial oxidation rate decreased with the addition of fullerenes. The addition of C 60 clusters in the MO decreased its viscosity with values lower than pure MO from start to finish of the autoxidation test. Ball on disk friction tests demonstrated that fullerenes effectively reduced the friction coefficient, favored by smaller C 60 clusters. The obtained results demonstrate that the introduction of small C 60 clusters in mineral oil exhibits higher antioxidation, and lower friction coefficient. Thus, C 60 could be of high interest as an additive for lubricant oils