Application of functionalized carbon nanofibers as a modifying additive to motor oil

• Published in: Diamond and related materials Vol. 146; p. 111207
• Main Authors: Afonnikova, Sofya D., Veselov, Grigory B., Larionov, Kirill B., Kibis, Lidiya S., Selyutin, Gennady E., Mishakov, Ilya V., Vedyagin, Aleksey A., Shubin, Yury V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-06-2024
• Subjects: Acidic treatment; Carbon nanofibers; Catalytic pyrolysis; Oxygen-containing functional groups; Tribological characteristics; Acidic treatment; Carbon nanofibers; Oxygen-containing functional groups; Catalytic pyrolysis; Tribological characteristics
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2024.111207

Due to the widespread of lubricants, improving their tribological characteristics remains an important practical task. Among the promising modifying additives, carbon nanomaterials attract special attention. Such materials are found to improve the antifriction characteristics of lubricants and oils. In the present research, carbon nanofibers were synthesized via catalytic pyrolysis of a mixture of light hydrocarbons (C2-C4) over the NiCu catalyst. In order to form functional groups on the surface of carbon nanofibers, they were treated with diluted acids HCl, HNO3, and H2SO4 as well as with concentrated HNO3. The functionalized samples were comprehensively characterized by a set of physicochemical methods including atomic absorption spectroscopy, scanning and transmission electron microscopies, low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, temperature-programmed desorption/oxidation, and Raman spectroscopy. As defined, the surface oxygen concentration in the samples varies from 3.5 to 16.3 at.%. It was shown that the addition of modified carbon nanofibers to a motor oil leads to an improvement in its tribological characteristics. In particular, the most effective additive was the sample treated with diluted HNO3. The motor oil with this modifying additive exhibited the heating temperature decreased by 10 °C and the contact spot area on the stationary body decreased by 20 %.
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•Treatment of CNF with dilute acids does not change their morphology and structure.•Acidic treatment of CNF promotes the formation of surface oxygen-containing groups.•Addition of functionalized CNF to motor oil reduces the heating temperature and decreases the contact spot.•High content of oxygen groups on the CNF surface deteriorates the tribological properties of the oil.