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O: Fachverband Oberflächenphysik

O 50: Poster Session IV: Tribology: Surfaces and nanostructures II

O 50.2: Poster

Dienstag, 2. März 2021, 13:30–15:30, P

Nanoscale wear mechanisms on bulk and monolayer molybdenum disulphide — •Alper Özogul¹, Felix Cassin¹, Andrey Turchanin², and Enrico Gnecco¹ — ¹Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany — ²Institute of Physical Chemistry, Friedrich Schiller University Jena, Germany

We have compared the response of MoS2 in the form of multi- and mono-layers grown on a silica substrate under abrasive wear conditions on the nanoscale [1]. The samples have been scratched with a sharp diamond tip with normal loads in the uN range and scan velocities in the um/s range. The resulting surface structures are characterized by AFM and related to the lateral force acting on the probing tip during scratching. On the bulk crystal distinct stick-slip motion is observed and sequences of chip structures are built up all along the scratch line. Characteristic parameters of this motion, namely the lateral contact stiffness and slip period are found to depend highly on the applied normal force and scratching velocity decreasing exponentially or, respectively, increasing logarithmically with them. Monolayer MoS2 is cracked along the zigzag direction and completely folded over itself while scratching. The time evolution of the lateral force is overall irregular although periodic structures, which possibly originate from rippling of silica substrate, can be recognized. First attempts to analyze the energetics of the complex processes so observed are also discussed.

[1] A. Özogul et al., Phys. Rev. Materials 4 (2020) 033603