Structural Lubricity and Molecular Contamination: Rejuvenation, Aging, and Friction Switches

Fuente: arXiv
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Autores principales: Oo, Wai H., Gao, Hongyu, Müser, Martin H., Baykara, Mehmet Z.
Formato: Preprint
Publicado: 2024
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author Oo, Wai H.
Gao, Hongyu
Müser, Martin H.
Baykara, Mehmet Z.
author_facet Oo, Wai H.
Gao, Hongyu
Müser, Martin H.
Baykara, Mehmet Z.
contents Using atomic force microscopy experiments and molecular dynamics simulations of gold nanoislands on graphite, we investigate why ultra-small friction commonly associated with structural lubricity can be observed even under ambient conditions. Measurements conducted within a few days after sample synthesis reveal previously undiscovered phenomena in structurally lubric systems: rejuvenation, a drop in kinetic friction of an order of magnitude shortly after the onset of sliding; aging, a significant increase in kinetic friction forces after a rest period of 30 minutes or more; switches, spontaneous jumps between distinct friction branches. These three effects are drastically suppressed a few weeks later. Imaging of a contamination layer and simulations provide a consistent picture of how single- and double-layer contamination underneath the gold nanoislands as well as contamination surrounding the nanoislands affect structural lubricity but not lead to its breakdown.
format Preprint
id arxiv_https___arxiv_org_abs_2407_03360
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Structural Lubricity and Molecular Contamination: Rejuvenation, Aging, and Friction Switches
Oo, Wai H.
Gao, Hongyu
Müser, Martin H.
Baykara, Mehmet Z.
Soft Condensed Matter
Using atomic force microscopy experiments and molecular dynamics simulations of gold nanoislands on graphite, we investigate why ultra-small friction commonly associated with structural lubricity can be observed even under ambient conditions. Measurements conducted within a few days after sample synthesis reveal previously undiscovered phenomena in structurally lubric systems: rejuvenation, a drop in kinetic friction of an order of magnitude shortly after the onset of sliding; aging, a significant increase in kinetic friction forces after a rest period of 30 minutes or more; switches, spontaneous jumps between distinct friction branches. These three effects are drastically suppressed a few weeks later. Imaging of a contamination layer and simulations provide a consistent picture of how single- and double-layer contamination underneath the gold nanoislands as well as contamination surrounding the nanoislands affect structural lubricity but not lead to its breakdown.
title Structural Lubricity and Molecular Contamination: Rejuvenation, Aging, and Friction Switches
topic Soft Condensed Matter
url https://arxiv.org/abs/2407.03360