title: Origin of ultralow friction and wear in ultrananocrystalline diamond.
abstract: The impressively low friction and wear of diamond in humid environments is debated to originate from either the stability of the passivated diamond surface or sliding-induced graphitization/rehybridization of carbon. We find ultralow friction and wear for ultrananocrystalline diamond surfaces even in dry environments, and observe negligible rehybridization except for a modest, submonolayer amount under the most severe conditions (high load, low humidity). This supports the passivation hypothesis, and establishes a new regime of exceptionally low friction and wear for diamond.
authors.affiliation: Department of Physics & Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Konicek
authors.forename: D S
authors.initials: DS
authors.lastname: Grierson
authors.forename: P U P A
authors.initials: PU
authors.lastname: Gilbert
authors.forename: W G
authors.initials: WG
authors.lastname: Sawyer
authors.forename: A V
authors.initials: AV
authors.lastname: Sumant
authors.forename: R W
authors.initials: RW
authors.lastname: Carpick