Tuning Autoxidation and Friction of Mineral Oil by Fullerene Cluster Properties

Lubricant oils can autoxidize due to contact with airand can beaccelerated by heat and catalyzed with metal ion impurities. Therefore,new antioxidant additives are needed. Carbon nanomaterials exhibitexcellent thermal oxidation resistance and can act as additives forlubricant oils to extend their operational lifetime. In this work,we studied the autoxidation behavior of a mixture of C-60/C-70 clusters in mineral oil (MO) containing differentamounts of toluene during mixing. The addition of toluene during mixingincreased the ratio of C-60/C-70 and the clustersize. The oil-fullerene mixtures (MO/C-60/70) were heatedat 150 & DEG;C for 48 h under magnetic stirring. FTIR analysis andTGA showed that the initial oxidation rate and high thermal oxidation(ca. 375 & DEG;C) decreased with the addition of fullerenes. Ballon disk friction tests showed that fullerenes effectively reducedthe friction coefficient, favored by smaller C-60/70 clusters.The obtained results demonstrate that small fullerene clusters withhigh C-70 content can be achieved without the addition oftoluene in mineral oil and exhibit higher antioxidation, and lowerfriction coefficient. Thus, fullerenes could be of high interest asan additive for lubricant oils.