Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 16: Scanning probe methods II
O 16.7: Vortrag
Montag, 26. März 2012, 17:30–17:45, MA 043
Superlubric sliding of metallic nanoparticles: The influence of contact area and crystallinity — •Dirk Dietzel1,2, Tristan Mönninghoff1, Michael Feldmann1,2, Udo D. Schwarz3, and Andre Schirmeisen1,2 — 1Institute of Applied Physics, University of Giessen — 2Institute of Physics & Center for Nanotechnology, University of Muenster — 3Dep. of Mech. Eng., Yale University, USA
The precise analysis of contact area dependence of nanoscale friction is a long standing problem in nanotribology. Currently, interest is especially spurred by the assumption that the scaling of friction with contact area might be a unique fingerprint to identify superlubric sliding. Superlubricity, or also termed structural lubricity, originates from the lattice mismatch at the interface of two atomically flat surfaces, and predicts a decrease of shear stress with contact area, and thus a sublinear contact area dependence of friction. To measure the interfacial friction we have manipulated metallic nanoparticles of different size on atomically flat surfaces by contact mode AFM techniques[1]. Our results confirm the sublinear scaling of friction with contact area. Moreover, we could identify different scaling factors for amorphous and crystalline particles. The experiments have been accompanied by numerical simulations of friction of Au and Sb particles on HOPG, which have indicated that not only contact area and crystallinity are important, but also the precise shape of the nanoparticle is crucial for friction. The good agreement between experiment and simulation enables us to quantitatively predict nanoscale friction from fundamental atomic quantities. [1]Dietzel et al., Phys. Rev. Lett. 101, 125505 (2008)