Ultra low friction of conductive carbon nanotube films and their structural evolution during sliding

• Published in: Diamond and related materials 2021-12, Vol.120, p.108617, Article 108617
• Main Authors: Zhang, Zhenxi, Yu, Guomin, Geng, Zhongrong, Tian, Pei, Ren, Kexin, Wu, Wenchao, Gong, Zhenbin
• Format: Article
• Language: English
• Subjects: Carbon; Carbon nanotube; Carbon nanotubes; Coefficient of friction; Conductivity; Electrical resistivity; Electrophoretic deposition; Evolution; Film thickness; Friction; Friction reduction; Lubricants; Lubrication; Mechanical systems; Rubbing; Shearing; Single crystals; Structure evolution
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2021.108617

Solid lubricating coatings with high conductivity are widely used in aerospace, tram and micro mechanical systems. In this study, a solid lubricating film with ultralow friction coefficient and good electrical conductivity was prepared using hydroxylated CNTs through electrophoretic deposition, and the structural evolutions when the CNT films act as lubricants are investigated in-depth. It was found that the electric resistance reduced significantly with the increase of the deposited CNT film thickness, and then it reached a saturation value of approximately 40 Ω at the film thickness of 0.7 ± 0.10 μm deposited at 50 V. Moreover, the friction coefficient was reduced by 71% at the deposition voltage of 40 V compare to the single crystal silicon. It is worth noting that the original carbon nanotubes transformed into nano-scrolls under the action of friction shearing and heating. At the same time, this work provided new insights for the structure evolution of carbon nanotube films during the rubbing process. [Display omitted] •The structure of the film evolved from carbon nanotube to nano-scroll.•COF was reduced by 71% when the CNTs were deposited on the silicon wafers.•Electric resistance of CNT film reached a saturation value of approximately 40 Ω.•Electrophoretic deposition is a green deposition method.