Abstract
One of the promising approaches to achieving large scale superlubricity is the use of junctions between existing ultra-flat surface together with superlubric graphite mesas. Here we studied the frictional properties of microscale graphite mesa sliding on the diamond-like carbon, a commercially available material with a ultra-flat surface. The interface is composed of a single crystalline graphene and a diamond-like carbon surface with roughness less than 1 nm. Using an integrated approach, which includes Argon plasma irradiation of diamond-like carbon surfaces, X-ray photoelectron spectroscopy analysis and Langmuir adsorption modeling, we found that while the velocity dependence of friction follows a thermally activated sliding mechanism, its temperature dependence is due to the desorption of chemical groups upon heating. These observations indicate that the edges have a significant contribution to the friction. Our results highlight potential factors affecting this type of emerging friction junctions and provide a novel approach for tuning their friction properties through ion irradiation.
Highlights
Graphite has been used as a solid lubricant and known to show ultralow friction since ancient times [1]
For all systems studied at T = 150 °C before irradiation we found a friction coefficient of about 0.008, indicating a superlubric state of graphite/Diamond-like carbon (DLC) heterojunctions
By investigating the temperature and velocity dependence of friction for microscale graphite/ DLC heterojunctions, we found that the velocity dependence follows the thermally activated sliding mechanism, whereas the observed temperature dependence cannot be explained based on existing theories
Summary
Graphite has been used as a solid lubricant and known to show ultralow friction since ancient times [1]. The relatively strong intralayer bonding and weak interlayer interaction lead to almost frictionless sliding at the incommensurate contact between single crystalline graphite surfaces, i.e., to the state called superlubricity [2]. Microscale heterojunctions of graphite and other materials including h-BN [18], MoS2 [19−21], mica [22], diamond-like carbon [23, 24] have been fabricated by transferring graphite mesas onto the target surface These heterostructures open wide opportunities for tuning interfacial frictional properties. In addition to studies of velocity and temperature dependence of friction, investigations of the effect of irradiation on friction may provide an essential information on mechanisms of sliding friction, since this method allows to tune the chemistry and structure of surfaces at atomic scale in a controllable way. X-ray photoelectron spectroscopy (XPS) characterizations revealed that Argon plasma irradiation removes the oxygen from the graphite edges, and converts part of sp carbon states into the sp states
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
