title: Tribological characteristics of few-layer graphene over Ni grain and interface boundaries.
abstract: The tribological properties of metal-supported few-layered graphene depend strongly on the grain topology of the metal substrate. Inhomogeneous distribution of graphene layers at such regions led to variable landscapes with distinguishable roughness. This discrepancy in morphology significantly affects the frictional and wetting characteristics of the FLG system. We discretely measured friction characteristics of FLG covering grains and interfacial grain boundaries of polycrystalline Ni metal substrate via an atomic force microscopy (AFM) probe. The friction coefficient of FLG covered at interfacial grain boundaries is found to be lower than that on grains in vacuum (at 10(-5) Torr pressure) and similar results were obtained in air condition. Sliding history with AFM cantilever, static and dynamic pull-in and pull-off adhesion forces were addressed in the course of friction measurements to explain the role of the out-of-plane deformation of graphene layer(s). Finite element simulations showed good agreement with experiments and led to a rationalization of the observations. Thus, with interfacial grain boundaries the FLG tribology can be effectively tuned.
authors.affiliation: Centre for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18, I-38123, Povo (Trento), Italy.
authors.forename: Manoj
authors.initials: M
authors.lastname: Tripathi
authors.affiliation: Centre for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18, I-38123, Povo (Trento), Italy.
authors.forename: Firas
authors.initials: F
authors.lastname: Awaja
authors.affiliation: CNR, Istituto Nanoscienze - Centro S3, Via Campi 213/a, I-41125 Modena, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Paolicelli
authors.affiliation: Centre for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18, I-38123, Povo (Trento), Italy.
authors.forename: Ruben
authors.initials: R
authors.lastname: Bartali
authors.affiliation: Centre for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18, I-38123, Povo (Trento), Italy.
authors.forename: Erica
authors.initials: E
authors.lastname: Iacob
authors.affiliation: Dipartimento di Scienze Fisiche Informatiche e Matematiche, Università di Modena e Reggio Emilia, via Campi 213/a, I-41125 Modena, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Valeri
authors.affiliation: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea.
authors.forename: Seunghwa
authors.initials: S
authors.lastname: Ryu
authors.affiliation: Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, I-38123 Trento, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Signetti
authors.affiliation: Centre for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18, I-38123, Povo (Trento), Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Speranza
authors.affiliation: Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, I-38123 Trento, Italy and Centre for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18, I-38123, Povo (Trento), Italy and School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS London, UK. nicola.pugno@unitn.it.
authors.forename: Nicola Maria
authors.initials: NM
authors.lastname: Pugno