Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Tribology
O 27.8: Vortrag
Dienstag, 19. März 2024, 12:15–12:30, MA 144
Effect of Amorphous-Crystalline Phase Transition on Superlubric Sliding — Ebru Cihan1,2, •Dirk Dietzel1, Benedykt Jany3, and Andre Schirmeisen1 — 1Institute of Applied Physics, Justus-Liebig-Universität Giessen, Germany — 2Institute for Materials Science and Max Bergmann Center for Biomaterials, TU Dresden, Germany — 3Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland
‘Structural superlubricity‘ describes a state of ultralow friction, that can be attributed to the lattice mismatch between two incommensurate surfaces in sliding motion. It is commonly anticipated that structural superlubricity is most effective for crystalline surfaces, while the irregular structure of amorphous surfaces leads to less efficient lateral force cancellations and thus higher friction. To verify this fundamental assumption, we analyzed friction of antimony nanoparticles sliding on HOPG for temperatures between 300 and 750K1 under UHV conditions. At about 420K a distinct and irreversible decrease in friction was observed. Based on complementary EBSD-analysis, this decrease was linked to a phase transition from amorphous to crystalline structure of the nanoparticles. More quantitatively, the results are described based on the Prandtl-Thomlinson model, where the relative changes of the effective energy barrier are correlated to a characteristic scaling factor γ that represents a measure for the crystalline state of the interface. γ is found to decrease by 20% and thereby also corroborates the influence of the phase transition on structural superlubricity.
1Cihan et al., PRL 130, 126205 (2023)