Robust microscale superlubricity under high contact pressure enabled by graphene-coated microsphere

• Published in: Nature communications Vol. 8; no. 1; p. 14029
• Main Authors: Liu, Shu-Wei, Wang, Hua-Ping, Xu, Qiang, Ma, Tian-Bao, Yu, Gui, Zhang, Chenhui, Geng, Dechao, Yu, Zhiwei, Zhang, Shengguang, Wang, Wenzhong, Hu, Yuan-Zhong, Wang, Hui, Luo, Jianbin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.02.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166/988; 639/925/918/1053; Boron; Carbon; Friction; Grain size; Graphene; Graphite; Humanities and Social Sciences; Microscopy; multidisciplinary; Relative humidity; Science; Science (multidisciplinary); Sliding friction; Beijing China; China
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms14029

Superlubricity of graphite and graphene has aroused increasing interest in recent years. Yet how to obtain a long-lasting superlubricity between graphene layers, under high applied normal load in ambient atmosphere still remains a challenge but is highly desirable. Here, we report a direct measurement of sliding friction between graphene and graphene, and graphene and hexagonal boron nitride (h-BN) under high contact pressures by employing graphene-coated microsphere (GMS) probe prepared by metal-catalyst-free chemical vapour deposition. The exceptionally low and robust friction coefficient of 0.003 is accomplished under local asperity contact pressure up to 1 GPa, at arbitrary relative surface rotation angles, which is insensitive to relative humidity up to 51% RH. This ultralow friction is attributed to the sustainable overall incommensurability due to the multi-asperity contact covered with randomly oriented graphene nanograins. This realization of microscale superlubricity can be extended to the sliding between a variety of two-dimensional (2D) layers. Superlubricity can be unstable in graphene systems, especially under high applied loads. Here the authors use microspheres uniformly coated by graphene to measure friction between 2D materials and show that superlow friction is preserved for long periods of time under high loads and various atmospheres.