Every autumn rail networks across the world suffer delays, accidents and schedule changes due to low friction problems caused by leaves landing on the rails. These leaves form a layer that can reduce the friction between the wheel and the rail to a similar level as that between ice and an ice-skate ( ). Previous works have generated several hypotheses for the chemical reactions and low friction mechanism associated with these layers. In this work, the reaction between an aqueous extract of sycamore leaves and metallic iron is investigated. This reaction has been shown to produce a black precipitate, which matches field observations of leaf layers, while friction tests with these extracts produce characteristic ultra low friction. The reaction is investigated through FTIR, XPS, CHNS and ICP-MS analysis as well as wet chemical testing. The impact of the reaction on friction is investigated through three rounds of tribological testing. The results indicate that the black precipitate produced is iron tannate, formed by complexation of tannins with dissolved iron ions. Friction testing showed that eliminating tannins from the leaf extract resulted in a significant increase in the friction coefficient compared with the control.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7426055 | PMC |
| http://dx.doi.org/10.1098/rspa.2020.0057 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Advanced Solid Lubrication with COK-47: Mechanistic Insights on the Role of Water and Performance Evaluation.
Adv Sci (Weinh)
January 2025
Institute for Engineering Design and Product Development, Research Unit Tribology E307-05, TU Wien, Vienna, 1060, Austria.
Metal-organic framework (MOF) nanoparticles have attracted widespread attention as lubrication additives due to their tunable structures and surface effects. However, their solid lubrication properties have been rarely explored. This work introduces the positive role of moisture in solid lubrication in the case of a newly described Ti-based MOF (COK-47) powder.
View Article and Find Full Text PDFIntramolecular Cyclization and Energetic Group Modifications for Thermally Stable and Low-Sensitivity Monocyclic Dinitromethyl Zwitterionic Pyrazoles.
Inorg Chem
January 2025
School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Zwitterionic energetic materials offer a unique combination of high performance and stability, yet their synthesis and stability enhancement remain key challenges. In this study, we report the synthesis of a highly stable (dinitromethyl-functionalized zwitterionic compound, 1-(amino(iminio)methyl)-4,5-dihydro-1H-pyrazol-5-yl)dinitromethanide (), with a thermal decomposition temperature of 215 °C, surpassing that of most previously reported energetic monocyclic zwitterions ( < 150 °C). This compound was synthesized via intramolecular cyclization of a trinitromethyl-functionalized hydrazone precursor.
View Article and Find Full Text PDFA Novel Self-Opening Transfer Shuttle for the Transfer of Air-Sensitive Sample to Scanning Electron Microscopy.
Microsc Microanal
January 2025
Instrumental Analysis Center, Dalian University of Technology, No.2 Linggong Road, Ganjingzi District, Dalian, Liaoning Province 116024, China.
A self-opening transfer shuttle has been designed and fabricated for the transfer of air-sensitive samples to scanning electron microscopy (SEM). Delayed push out of an airtight sample cabin sealed inside the shuttle allows the protection of the sample from air exposure during the pumping of SEM chamber. A compressed spring is employed to automatically drive the push out of the cabin.
View Article and Find Full Text PDFTribological Performance of Short Fibers Reinforced Thermoplastic Polyurethane Composite Materials Under Water-Lubricated Condition.
Polymers (Basel)
December 2024
School of Transportation and Logistics Engineering, Wuhan University of Technology, Wuhan 430063, China.
The water-lubricated bearing plays a crucial role in the ship propulsion system, significantly impacting vessel safety. However, under the harsh working conditions of low-speed and heavy-load, the lubrication state of water-lubricated bearings is usually poor, leading to serious friction and wear. To improve the tribological performance of composites and reduce friction, three short fibers (ultra-high-molecular-weight polyethylene fibers, basalt fibers, and bamboo fibers) with the same mass fraction (5%) were added into the melted thermoplastic polyurethane (TPU).
View Article and Find Full Text PDFBoundary Lubrication with Adsorbed Anionic Surfactant Bilayers in Hard Water.
Langmuir
January 2025
R&D - Analytical Science Research, Kao Corporation, 1334 minato, Wakayama, Wakayama 640-8580, Japan.
The adsorption behavior of an anionic surfactant, hydroxy alkane sulfonate with an alkyl chain length of 18 (C18HAS), from its hard water solution onto a mica surface and resulting lubrication properties were investigated. Because of the double chain-like chemical structure and aggregation behavior, C18HAS formed vesicles in hard water, which adsorbed onto a negatively charged mica surface via cation (Ca) bridging and then transformed into a bilayer film. The number of bilayers formed on the surface was evaluated by force curve measurements using an atomic force microscope (AFM), and the results showed a time-dependent increase of the number of adsorbed bilayers.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!