Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 39: Tribology

O 39.3: Talk

Wednesday, September 7, 2022, 11:00–11:15, H6

The Influence of Temperature and Wear on Nanoscale Friction Anisotropy — •Jennifer Konrad, Dirk Dietzel, and Andre Schirmeisen — Institute of Applied Physics, Justus-Liebig University Giessen, 35392 Giessen, Germany

On atomically flat surfaces, the nanoscale friction force measured by atomic force microscopy shows a distinct variations dependent on the sliding direction of the AFM-tip. This anisotropy occurs as a consequence of the surface structure and is related to different energy barrier heights along different directions of the sample surface. In this work, this anisotropy of friction force is now analyzed as a function of temperature under UHV conditions on hexagonal latices like HOPG or MoS2 and also on ionic crystals with 90 degree symmetry like NaCl. At low sample temperatures, the friction force as deduced from the thermally activated Prandtl Tomlinson Model increases, and thermally activated random jumps become more unlikely, which direct influences the stability of the different sliding directions. This can be confirmed for HOPG and MoS2, while, our results for the ionic crystals additionally show that the both the absolute friction and the anisotropy are not only influenced by temperature, but also reflect temperature dependent wear effects.