title: Superlubricity in centimetres-long double-walled carbon nanotubes under ambient conditions.
abstract: Friction and wear are two main causes of mechanical energy dissipation and component failure, especially in micro/nanomechanical systems with large surface-to-volume ratios. In the past decade there has been an increasing level of research interest regarding superlubricity, a phenomenon, also called structural superlubricity, in which friction almost vanishes between two incommensurate solid surfaces. However, all experimental structural superlubricity has been obtained on the microscale or nanoscale, and predominantly under high vacuum. Here, we show that superlubricity can be realized in centimetres-long double-walled carbon nanotubes (DWCNTs) under ambient conditions. Centimetres-long inner shells can be pulled out continuously from such nanotubes, with an intershell friction lower than 1 nN that is independent of nanotube length. The shear strength of the DWCNTs is only several pascals, four orders of magnitude lower than the lowest reported value in CNTs and graphite. The perfect structure of the ultralong DWCNTs used in our experiments is essential for macroscale superlubricity.
authors.affiliation: Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Rufan
authors.initials: R
authors.lastname: Zhang
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Ning
authors.forename: Yingying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Quanshui
authors.initials: Q
authors.lastname: Zheng
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Xie
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Weizhong
authors.initials: W
authors.lastname: Qian
authors.forename: Fei
authors.initials: F
authors.lastname: Wei
mesh_terms: D006108:Graphite / Q000737:chemistry; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D006108:Graphite