AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Monday Sessions
       Session NS1-MoA

Paper NS1-MoA9
The Observation of Nanoscale Melting at Sliding Interface

Monday, October 31, 2005, 4:40 pm, Room 204

Session: Nanotribology
Presenter: S.M. Lee, North Carolina State University
Authors: S.M. Lee, North Carolina State University
J. Krim, North Carolina State University
Correspondent: Click to Email
Tribological phenomena occurring at buried interfaces undergoing shear are extremely difficult to characterize experimentally, especially since the characterizations must ideally be performed at both atomic length and time scales. We report here one such investigation, involving a scanning probe tip sliding along the metal film electrode of a quartz crystal microbalance (QCM). The atomically sharp STM tip allows the generation of the nano-scale interface area while the sharp resonance of QCM allows measurement of the interaction forces applied to its surface. This in turn yields fundamental information on energy dissipation mechanisms associated with the sliding. For a W-tip sliding along a copper surface, we have observed nano-scale melting that is attributable to the rubbing action of the tip. As the rubbing velocity at the interface increases, the frequency shift converted from the positive to the negative when the interface area melts. Additionally, QCM amplitude shifts are enhanced by ~ 5 times upon melting of the interface. This observation implies that the nano-scale local temperature can be controlled by the rubbing velocity at the film-tip interface. And the temperature rise by rubbing can easily go over 1000°C, since the melting point of copper is 1084.62°C. The experimental results will be discussed with in the context of an extended Laschitsch and Johannsmann (LJ) model.@footnote 1@ @FootnoteText@ @footnote 1@ B. Borovsky, J. Krim, S. A. Syed Asif, and K. J. Wahl, J. Appl. Phys., 90, 6391 (2001)@footnote *@ This work has been supported by the DOE and the AFOSR Extreme Friction MURI program.