Objective: The aim of this study was to analyze the surface composition, roughness, and relative friction of metal clips from various ceramic self-ligating brackets.
Methods: Six kinds of brackets were examined. The control group (mC) consisted of interactive metal self-ligating brackets while the experimental group (CC, EC, MA, QK, and WA) consisted of interactive ceramic self-ligating brackets. Atomic force microscopy-lateral force microscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy were used to analyze the surface of each bracket clip.
Results: All the clips in the experimental groups were coated with rhodium except for the QK clip. The results showed that the QK clip had the lowest average roughness on the outer surface, followed by the MA, EC, WA, and CC clips. However, the CC clip had the lowest average roughness on the inner surface, followed by the QK, WA, MA, and EC clips. The QK clip also had the lowest relative friction on the outer surface, followed by the MA, EC, CC, and WA clips. Likewise, the CC clip had the lowest relative friction on the inner surface, followed by the QK, WA, MA, and EC clips.
Conclusions: The surface roughness and relative friction of the rhodium-coated clips were generally higher than those of the uncoated clips.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306314 | PMC |
http://dx.doi.org/10.4041/kjod.2019.49.1.12 | DOI Listing |
Nat Commun
January 2025
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, China.
Micro actuators are widely used in NEMS/MEMS for control and sensing. However, most are designed with suspended beams anchored at fixed points, causing two main issues: restricted actuated stroke and movement modes, and reduced lifespan due to fatigue from repeated beam deformation, contact wear and stiction. Here, we develop an electrostatic in-plane actuator leveraging structural superlubric sliding interfaces, characterized by zero wear, ultralow friction, and no fixed anchor.
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January 2025
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, MA, 02134, USA.
Many aquatic organisms utilize suction-based organs to adhere to diverse substrates in unpredictable environments. For multiple fish species, these adhesive discs include a softer disc margin consisting of surface structures called papillae, which stabilize and seal on variable substrates. The size, arrangement, and density of these papillae are quite diverse among different species, generating complex disc patterns produced by these structures.
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January 2025
Civil and Environmental Engineering Department, Faculty of Engineering Sciences, Ben- Gurion University of the Negev, Beer-Sheva, Israel.
The concept of friction was integrated into the broader field of tribology in the 20th century. Here, we revive the older friction coefficient concept and show that it is the defining parameter for a family of granular materials. We show, for the first time, that kinetic friction coefficients of such systems can be described as a function of the lubricating fluid and the shape of the granules, without any fitting parameters.
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January 2025
Beijing Solidwel Intelligent Technology Co., Ltd., BeiJing, 100000, China.
Based on the Johnson-Cook constitutive model and modified Coulomb's law, the study investigates the impact of various process parameters on the weld temperature field in high-strength 5052 aluminum alloy friction stir welding (FSW) for aerospace applications. Utilizing a thermo-mechanical model, the significance of rotational speed, welding speed, and indentation on the peak weld temperature is examined through Taguchi's orthogonal experimental design. S/N ratio and ANOVA results show that the rotational speed has the most significant effect on the peak temperature of the weld, followed by the amount of indentation, and the welding speed has the smallest effect, the optimal combination of welding process parameters is determined as follows:the rotational speed is 1000 rpm, the amount of indentation is 0.
View Article and Find Full Text PDFRSC Adv
December 2024
Department of Human Ecology, Korea National Open University Seoul 03087 Republic of Korea
This study aimed to determine optimal washing and drying methods for maintaining the functionality of silver-coated conductive knitted fabrics, commonly used in wearable smart products. By investigating changes in the physical, chemical, and electrical properties of these fabrics under various care conditions, we sought to provide recommendations for their proper maintenance. Results showed that mechanical friction during washing, combined with the chemical effect of detergent and the effects of machine drying, led to peeling and oxidation of the silver layer, resulting in changes to the fabric's appearance, color and increased surface resistance.
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