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排序方式: 共有919条查询结果,搜索用时 525 毫秒
911.
Wear investigations concerning the different structures and metal atoms of metal dialkyldithiophosphates (MeDTPs) were conducted using a ball‐on‐disc apparatus. Steel ball bearings (3.175 mm in diameter) and counterface discs, made of hot pressed ZrO2 partially stabilised by Y2O3, were used. The synthesised MeDTPs were made up of primary linear aliphatic alcohols with hydrocarbon lengths varying from 8 to 16 carbon atoms, and contained the following metals: zinc(II), iron(III), gallium(III), antimony(III), and copper(II). Tests were performed at room temperature. The sliding speed was set to a constant 0.03 m/s, and a constant 30 N load was used. The additives investigated were used as solutions in n‐hexadecane. The study also focused on the influence of additive concentration on wear. It was found that the effectiveness in reducing wear depends both on the metal atom and on the length of the hydrocarbon chain in the additive's molecules. The lowest wear volumes were observed for additives with n‐octyl and n‐tetradecyl hydrocarbon chains. The worst antiwear performance was observed for n‐dodecyl derivatives. For almost all additives, more concentrated solutions resulted in less wear. Some friction coefficient results are also presented. 相似文献
912.
The friction and wear behaviour of thin hard coatings, such as TiN and the promising class of C-based coatings (a-C, a-C:H, and diamond for example), are compared under oscillating and reciprocating sliding conditions. The typical effects of test parameters, such as stroke, frequency, normal force, relative humidity and test duration, are described as a basis for the proper selection of test conditions or, conversely, for the selection of suitable coatings for particular practical applications. Friction and wear data from over 1000 vibrating tests using thin hard coatings against 100Cr6 and against Al2O3 have been compiled in a database. This allows easy manipulation and comparison of test results. Using selection criteria and filter procedures (e. g., lifetime of coatings, friction limits, and critical wear rate), suitable coating systems for different test conditions can be chosen from the database. The effects of test parameters on friction and wear behaviour and changes have anyway to be known for meaningful tribotesting, as well as for the selection of coatings. 相似文献
913.
Zhendong Yang Letian Chen Haoyang Jiang Xinghui Liang Jinping Wei Zhaojun Xie Bin Tang Zhen Zhou 《Advanced functional materials》2023,33(47):2306558
Solid-state sodium batteries have garnered considerable interest. However, their electrochemical performance is hampered by severe interfacial resistance between sodium metal and inorganic solid electrolytes, as well as Na dendrite growth within the electrolytes. To address these issues, a uniform and compact SnF2 film is first introduced onto the surface of the inorganic solid electrolyte Na3.2Zr1.9Ca0.1Si2PO12 (NCZSP) to improve contact through an effective and straightforward process. Through experiments and computations, the in situ conversion reaction between SnF2 and molten Na is adequately confirmed, resulting in a composite conductive layer containing NaxSn alloys and NaF at the interface. As a result, the interfacial resistance of Na/NCZSP is significantly decreased from 813 to 5 Ω cm2, and the critical current density is dramatically increased to 1.8 mA cm−2, as opposed to 0.2 mA cm−2 with bare NCZSP. The symmetric cell is able to cycle stably at 0.2 mA cm−2 for 1300 h at 30 °C and exhibits excellent current tolerance of 0.3 and 0.5 mA cm−2. Moreover, the Na3V2(PO4)3/SnF2-NCZSP/Na full cell displays excellent rate performance and cycling stability. The SnF2-induced interlayer proves significant in improving interfacial contact and restraining sodium dendrite propagation, thus promoting the development of solid-state sodium batteries. 相似文献
914.
Saima Batool Muhammad Idrees Su-Ting Han Vellaisamy A. L. Roy Ye Zhou 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(12):2206550
Current electrical contact models are occasionally insufficient at the nanoscale owing to the wide variations in outcomes between 2D mono and multi-layered and bulk materials that result from their distinctive electrostatics and geometries. Contrarily, devices based on 2D semiconductors present a significant challenge due to the requirement for electrical contact with resistances close to the quantum limit. The next generation of low-power devices is already hindered by the lack of high-quality and low-contact-resistance contacts on 2D materials. The physics and materials science of electrical contact resistance in 2D materials-based nanoelectronics, interface configurations, charge injection mechanisms, and numerical modeling of electrical contacts, as well as the most pressing issues that need to be resolved in the field of research and development, will all be covered in this review. 相似文献
915.
A key feature that distinguishes cancer cells from all other cells is their capability to spread throughout the body. Although how cancer cells collectively migrate by following molecular rules which influence the state of cell-cell adhesion contacts has been comprehensively formulated, the impact of physical interactions on cell spreading remains less understood. Cumulative effects of physical interactions exist as the interplay between various physical parameters such as (1) tissue surface tension, (2) viscoelasticity caused by collective cell migration, and (3) solid stress accumulated in the cell aggregate core region. This review aims to point out the role of these physical parameters in cancer cell spreading by considering and comparing the rearrangement of various mono-cultured cancer and epithelial model systems such as the fusion of two cell aggregates. While epithelial cells undergo volumetric cell rearrangement driven by the tissue surface tension, which directs cell movement from the surface to the core region of two-aggregate systems, cancer cells rather perform surface cell rearrangement. Cancer cells migrate toward the surface of the two-aggregate system driven by the solid stress while the surface tension is significantly reduced. The solid stress, accumulated in the core region of the two-aggregate system, is capable of suppressing the movement of epithelial cells that can undergo the jamming state transition; however, this stress enhances the movement of cancer cells. We have focused here on the multi-scale rheological modeling approaches that aimed at reproducing and understanding these biological systems. 相似文献
916.
Dianyu Qi Peng Li Haohui Ou Di Wu Weiguang Lian Zhuo Wang Fangping Ouyang Yang Chai Wenjing Zhang 《Advanced functional materials》2023,33(27):2301704
2D semiconductors have shown great potentials for ultra-short channel field-effect transistors (FETs) in next-generation electronics. However, because of intractable surface states and interface barriers, it is challenging to realize high-quality contacts with low contact resistances for both p- and n- 2D FETs. Here, a graphene-enhanced van der Waals (vdWs) integration approach is demonstrated, which is a multi-scale (nanometer to centimeter scale) and reliable (≈100% yield) metal transfer strategy applicable to various metals and 2D semiconductors. Scanning transmission electron microscopy imaging shows that 2D/2D/3D semiconductor/graphene/metal interfaces are atomically flat, ultraclean, and defect-free. First principles calculations indicate that the sandwiched graphene monolayer can eliminate gap states induced by 3D metals in 2D semiconductors. Through this approach, Schottky barrier-free contacts are realized on both p- and n-type 2D FETs, achieving p-type MoTe2, p-type black phosphorus and n-type MoS2 FETs with on-state current densities of 404, 1520, and 761 µA µm−1, respectively, which are among the highest values reported in literature. 相似文献
917.
José Carlos Pérez-Martínez Mariana Berruet Cedric Gonzales Saeed Salehpour Ali Bahari Belén Arredondo Antonio Guerrero 《Advanced functional materials》2023,33(47):2305211
Halide perovskites are promising candidates for resistive memories (memristors) due to their mixed electronic/ionic conductivity and the real activation mechanism is currently under debate. In order to unveil the role of the metal contact and its connection with the activation process, four model systems are screened on halide perovskite memristors: Nearly inert metals (Au and Pt), low reactivity contacts (Cu), highly reactive contact (Ag and Al), and pre-oxidized metal in the form of AgI. It is revealed that the threshold voltage for activation of the memory effect is highly connected with the electrochemical activity of the metals. Redox/capacitive peaks are observed for reactive metals at positive potentials and charged ions are formed that can follow the electrical field. Activation proceeds by formation of conductive filaments, either by the direct migration of the charged metals or by an increase in the concentration of halide vacancies generated by this electrochemical reaction. Importantly, the use of pre-oxidized Ag+ ions leads to very low threshold voltages of ≈0.2 V indicating that an additional electrochemical reaction is not needed in this system to activate the memristor. Overall, the effect of the metal contact is clarified, and it is revealed that AgI is a very promising interfacial layer for low-energy applications. 相似文献
918.
Hongmei Gao Yimin Jiang Ru Chen Chung-Li Dong Yu-Cheng Huang Mingyu Ma Zude Shi Jiaqi Liu Zijin Zhang Mengyi Qiu Tianyu Wu Jinbo Wang Yubin Jiang Jun Chen Xiuyun An Yongmin He Shuangyin Wang 《Advanced functional materials》2023,33(46):2214795
The high cost of noble metals is one of the key factors hindering the large-scale application of proton exchange membrane (PEM) water electrolyzer for hydrogen production. Recently, single-atom catalysts (SACs) with a potential of maximum atom utilization efficiency enable lowering the metal amount as much as possible; unfortunately, their durability remains a challenge under PEM water electrolyzer working conditions. Herein, a highly-stable alloyed Pt SAC is demonstrated through a plasma-assisted alloying strategy and applies to a PEM water electrolyzer. In this catalyst, single Pt atoms are firmly anchored onto a Ru support via a robust metal–metal bonding strength, as evidenced by these complementary characterizations. This SAC is used in a PEM water electrolyzer system to achieve a cell voltage as low as 1.8 V at 1000 mA cm−2. Impressively, it can operate over 1000 h without obvious decay, and the catalyst is present in the form of individual Pt atoms. To the knowledge, this will be the first SAC attempt at a cell level toward long-term PEM. This work paves the way for designing durable SACs employed in the actual working condition in the PEM water electrolyzer. 相似文献
919.
This paper presents a relatively complete numerical solution to time-dependent micro-thermoelastohydrodynamic lubrication in line contacts subjected to constant load and entraining velocity. Sinusoidal functions are employed to model the traverse roughness on contact surfaces. The Eyring model is used to describe the non-Newtonian flow of the lubricant. With respect to time, the problem is treated as a periodic one so that most variables, such as pressure, film thickness and temperature, can be considered as periodic functions. An efficient algorithm is developed, and a number of cases are solved. The results indicate that the lubricant squeeze induced by the motion and interaction of rough surfaces significantly affects the solution of micro-thermoelastohydrodynamic lubrication. 相似文献