Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 120: Tribology: Surfaces and nanostructures
O 120.2: Talk
Friday, March 16, 2018, 11:45–12:00, MA 144
Temperature dependent Contact Ageing Dynamics of Silica Nano-Junctions — •Matthias Vorholzer1, Guilherme Vilhena2, Dirk Dietzel1, Ruben Perez2, Enrico Gnecco3, and Andre Schirmeisen1 — 1Institute of Applied Physics, Justus-Liebig-University, Giessen, Germany — 2Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain — 3Department for Mechanics of Functional Materials, Friedrich-Schiller-University, Jena, Germany
Contact ageing is a fundamental part of rate and state friction laws, which are commonly used to describe macroscale friction. Here, ageing is typically linked to changes of the contact area. Recent nanoscale experiments showed similar ageing for silica nano-junctions, but the effects were attributed to interfacial bond formation [1, 2]. Now, we are probing the temperature dependence of ageing to pinpoint further details about the intrinsic process. We present results for single-asperity slide-hold-slide [1] experiments under UHV conditions for temperatures ranging from 200 K to 300 K for a silica-silica interface. Key for our analysis is measuring the pre-rupture contact stiffness instead of static friction. Our results show logarithmic contact ageing at all temperatures with the expected temperature dependent slope. Additional MD simulations were conducted, which show a striking agreement to the experiments, thereby confirming thermally activated formation of chemical bonds as the governing process for ageing.
[1] Q. Li et al., Nature 480, 233 (2011)
[2] K. Tian et al., PRL 118, 076103 (2017)