Large-scale quantum molecular dynamics of water-lubricated diamond (111) surfaces in sliding contact reveals multiple friction regimes. While water starvation causes amorphization of the tribological interface, small H_{2}O traces are sufficient to preserve crystallinity. This can result in high friction due to cold welding via ether groups or in ultralow friction due to aromatic surface passivation triggered by tribo-induced Pandey reconstruction. At higher water coverage, Grotthuss-type diffusion and H_{2}O dissociation yield dense H/OH surface passivation leading to another ultralow friction regime.
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http://dx.doi.org/10.1103/PhysRevLett.119.096101 | DOI Listing |
Prev Nutr Food Sci
December 2024
Department of Food Science and Biotechnology, Dongguk University-Seoul, Gyeonggi 10326, Korea.
This study investigated the rheological and tribological properties of cold beverages [bottled water (BW), sports drink (SD), orange juice (OJ), and whole milk (WM)] thickened with various concentrations (1%, 2%, and 3%, w/w) of xanthan gum-based food thickeners. All thickened beverages exhibited high pseudoplastic behavior, with increasing thickener concentration leading to higher viscosity and viscoelastic moduli and a lower flow behavior index. Thickened BW, SD, and WM exhibited typical Stribeck curves covering the boundary, mixed, and hydrodynamic lubrication regimes.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Mechanical Engineering, College of Engineering, University of Ha'il, 81451, Ha'il City, Saudi Arabia.
Non-Newtonian fluids are also widely used in a variety of scientific, engineering, and industrial domains, including the petroleum sector and polymer technologies. They are vital in the development of drag-reducing agents, damping and braking systems, food manufacturing, personal protective equipment, and the printing industry. Fluid movement and transport via porous materials draw a lot of attention; they are important in science and technology.
View Article and Find Full Text PDFSci Rep
December 2024
School of architecture, Ocean and energy power engineering, Wuhan University of Technology, Wuhan, 430070, China.
During maritime operations, extreme events such as explosions, grounding, and seal failures can cause water ingress into lubricant compartments, forming oil-water emulsions that significantly affect the lubrication performance of ship stern bearings. Existing studies mainly focus on low water content, with limited exploration of the impact of high water content on lubrication performance. To address this gap, viscosity measurements of oil-water mixtures were conducted, and an emulsification viscosity equation applicable to varying water contents was derived.
View Article and Find Full Text PDFPhys Rev E
November 2024
CEA, DAM, DIF- 91297 Arpajon, France and Université Paris-Saclay, CEA, Laboratoire Matière en Conditions Extrêmes (LMCE), 91680 Bruyères-le-Châtel, France.
The nonlinear evolution of bubble and spike fronts growing through the generalized Rayleigh-Taylor instability are studied by numerical simulations and by solving an extension of Alon's [Phys. Rev. E 48, 1008 (1993)2470-004510.
View Article and Find Full Text PDFMaterials (Basel)
November 2024
Faculty of Mechanical Engineering, Poznań University of Technology, Piotrowo 3, 61-138 Poznań, Poland.
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