2, Adamas Nanotechnologies, Raleigh, North Carolina, United States
Development of new lubricants and lubricant additives is critical from both energy conservation and environmental impact viewpoints. Current oil-based technologies, which were developed with a focus on wear reduction, rely heavily on sulfur, phosphorous and/or chlorine based additives that have a propensity for bioaccumulation and environmental toxicity. Another key additive in lubricant formulations are antioxidants which are geared toward minimizing the content of acids, alcohols, aldehydes, ketones, esters and peroxides formed as a result of high temperature oxidation of hydrocarbon chains. Conventional antioxidant components often contain toxic elements. Recent studies have shown that nanocarbon based additives to lubricants can provide significant performance enhancement while mitigating environmental concerns. It was demonstrated that lubricant formulations containing detonation nanodiamond (ND) particles with small aggregate sizes are capable of reducing friction and wear at sliding interfaces due to nano-polishing , while fullerene (C60) nanoparticles show antioxidant effects upon addition to oils . A goal of the present work was to investigate if a combination of NDs and C60 can provide a synergism of enhanced tribological and antioxidant properties of polyalphaolefin (PAO) and mineral oils.
Oxidation properties of mineral oil I-20A and PAO-6 oil containing NDs, detonation soot or commercial additives containing ND or detonation soot (ADDO, Karat-5, D-Tribo) has been examined and compared with the oil containing C60 and a conventional antioxidant (N-Phenyl-2-naphthylamine) upon heating at 180oC for 6 hours. The degradation characteristics of the base oils were determined by physical and chemical tests and through FTIR spectroscopy in the region 1800–1650 cm-1. Tests of physical and chemical properties included determination of changes in viscosity and the total acid number (TAN).Both fullerene C60 and ND (but not detonation soot) showed antioxidant properties in the mineral oil and PAO at high temperature. The effects of ND deagglomeration approaches and a method of preparation of colloidal ND in oil on their antioxidant properties will also be discussed. The effect of co-additives (ND and ND/C60) in PAO-6 oil on the tribological properties of the formulation are also reported.
M Ivanov, O Shenderova, Nanodiamond-based nanolubricants for motor oils, Current Opinion in Solid State and Materials Science, 21 (1), p.17-24 (2017)
Zmarzly, D.; Dobry, D. Analysis of properties of aged mineral oil doped with C60 fullerenes. IEEE Trans. Dielectr. Electr. Insul. 2014, 21, 1119–1126.