Persistence of Structural Lubricity on Contaminated Graphite: Rejuvenation, Aging, and Friction Switches.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39311444.
- Also identified by DOI 10.1021/acs.nanolett.4c02883 and PMC identifier 11450813.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Using atomic force microscopy experiments and molecular dynamics simulations of gold nanoislands on graphite, we investigate why ultralow 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: <i>rejuvenation</i>, a drop in kinetic friction of an order of magnitude shortly after the onset of sliding; <i>aging</i>, a significant increase in kinetic friction forces after a rest period of 30 min or more; and <i>switches</i>, 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 without leading to its breakdown.