检索结果-南通市图书馆

Tribological behavior of CNTs-Cu and graphite-Cu composites with electric current

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2012年第1期22卷 78-84页

作者： XU Wei HU Rui LI Jin-shan ZHANG Yong-zhen FU Heng-zhi State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Engineering School Shanxi Datong UniversityDatong 037003China Laboratory of Material Tribology Henan University of Science and TechnologyLuoyang 471003China

CNTs-Cu and graphite-Cu composites were separately prepared by powder metallurgy technique under the same consolidation processing. Tribological behavior of the composites with electric current was investigated by using a pin-on-disk friction and wear tester. The results show that the friction coefficient and wear rate of the composites decrease with increasing the reinforcement content, and increase with increasing the electric current density; the effects of electric current are more obvious on tribological properties of graphite-Cu composites than on CNTs-Cu composites; for graphite-Cu composites the dominant wear mechanisms are electric arc erosion and adhesive wear, while for CNTs-Cu composites are adhesive wear.

关键词： Cu matrix composite tribological behaviors electric current wear mechanisms

Tribological and electric-arc behaviors of carbon/copper pair during sliding friction process with electric current applied

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第2期21卷 292-299页

作者：林修洲朱旻昊莫继良陈光雄金学松周仲荣西南交通大学牵引动力国家重点实验室摩擦学研究所成都610031 四川理工学院材料与化学工程学院自贡643000

The tribological behaviors of carbon block sliding against copper ring with and without electric current applied were investigated by using an advanced multifunctional friction and wear tester, and the electric-arc behaviors were analyzed in detail. The results show that the normal load is one of the main controlling factors for generation of electric arc during friction process with electric current applied. The strength of electric arc is enhanced with the decrease of normal loads and the increase of electric currents. The unstable friction process and the fluctuated dynamic friction coefficients are strongly dependent upon the electric arc. The wear volumes and the wear mechanism of carbon brush were affected by the electric arc obviously. As no electric arc occurs, no clear discrepancy of the wear volumes of the carbon samples with and without electric current applied could be detected. While the wear mechanisms are mainly mechanical wear. However, under the condition of the electric arc appearance, the wear volume of carbon with electric current applied increases much more rapidly than that without electric current applied and also increases obviously with the increase of electric current strengths and the decrease of normal loads. The wear mechanisms of carbon block are mainly electric arc ablation accompanying with adhesive wear and material transferring.

关键词： friction wear electric current electric arc carbon/copper

Influence of electric current on Kirkendall Diffusion of Zn/Cu Couples

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第3期24卷 410-414页

作者： Yingju LI Yuansheng YANG Xiaohui FENG Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The influence of electric current on Kirkendall diffusion in Zn/Cu couples was investigated. Under the action of different electric currents, the Zn/Cu diffusion couples were annealed at 785℃ for different holding time. The experimental results show that the displacement of the Kirkendall plane increases with increasing holding time. However, the displacement of the Kirkendall plane with electric current is larger than that without electric current. The relationship between the displacement of the Kirkendall plane and the holding time is changed under the action of electric current. The likely reason for the electric current enhancing effect is the energy transfer from electron to jumping atom, increasing the integrated diffusion coefficient, which leads to the increase in the velocity of Kirkendall plane.

关键词： electric current Electromigration Kirkendall effect Darken equations

Influence of applied load on wear behavior of C/C-Cu composites under electric current

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2017年第2期27卷 192-196页

作者： Jian Yin Hongbo Zhang Xiang Xiong Huijin Tao Pei Wang Chaoyong Deng State Key Laboratory of Powder Metallurgy Central South University College of Materials Science and Technology Central South University

Using carbon fiber needled fabrics with Cu-mesh and graphite powder as the preform, Cu mesh modified carbon/carbon（C/C-Cu） composites were prepared by chemical vapor deposition（CVD） with C;H;and impregnation-carbonization（I/C） with furan resin. C/C composites, as a comparison, were also *** microstructures and wear morphologies were observed by optical microscopy（OM） and scanning electron microscope（SEM）, respectively. Wear behavior of C/C and C/C-Cu composites under different applied loads were investigated on a pin-on-disc wear tester. The results show that Cu meshes are well dispersed and pyrolytic carbon is in rough laminar structure. Both C/C and C/C-Cu composites had good wear properties. The currentcarrying capacity of C/C-Cu composites increases and the arc discharge is hindered as the applied load increases from 40 N to 80 N. Both C/C and C/C-Cu composites had good wear properties. The mass wear rate of C/C-Cu composites under 80 N was only 4.2% of that under 60 N. In addition, C/C-Cu composites represent different wear behaviors because wear mechanisms of arc erosion, abrasive wear, adhesive wear, and oxidative wear are changing under different applied loads.

关键词： Carbon/Carbon-Copper composites Pantograph slider Wear electric current Applied load

A new brain stimulation method: Noninvasive transcranial magneto–acoustical stimulation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第8期25卷 222-227页

作者：袁毅陈玉东李小俚 Institute of electrical Engineering Yanshan University State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research Beijing Normal University Center for Collaboration and Innovation in Brain and Learning Sciences Beijing Normal University

We investigate transcranial magneto–acoustical stimulation（TMAS） for noninvasive brain neuromodulation in *** as a novel technique uses an ultrasound wave to induce an electric current in the brain tissue in the static magnetic field. It has the advantage of high spatial resolution and penetration depth. The mechanism of TMAS onto a neuron is analyzed by combining the TMAS principle and Hodgkin–Huxley neuron model. The anesthetized rats are stimulated by TMAS, resulting in the local field potentials which are recorded and analyzed. The simulation results show that TMAS can induce neuronal action potential. The experimental results indicate that TMAS can not only increase the amplitude of local field potentials but also enhance the effect of focused ultrasound stimulation on the neuromodulation. In summary, TMAS can accomplish brain neuromodulation, suggesting a potentially powerful noninvasive stimulation method to interfere with brain rhythms for diagnostic and therapeutic purposes.

关键词： transcranial magneto-acoustical stimulation brain neuromodulation electric current Hodgkin-Huxley neuron model

Solidification of Immiscible Alloys Under the Effect of electric and Magnetic Fields

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1240-1248页

作者： Hong-Xiang Jiang Jiu-Zhou Zhao Institute of Metal Research Chinese Academy of Sciences

Immiscible alloys have aroused considerable interests in the last decades on account of their special physical andmechanical properties and potential applications. A considerable number of researches have been implemented toinvestigate the solidification behaviors of immiscible alloys in electric and magnetic fields. It has been indicated that themagnetic field and electric current can remarkably affect the solidification process and microstructures of immisciblealloys. The solidification techniques under the effects of electric and magnetic fields have great potentials for the fabri-cation of immiscible alloys. This paper reviews the research work in this field in recent years.

关键词： Immiscible alloys Solidification Microstructure evolution electric current Magnetic field electric-magnetic fields

Grain nucleation and growth behavior of a Sn-Pb alloy affected by direct current： An in situ investigation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第10期33卷 1134-1140页

作者： Fenfen Yang Zongning Chen Fei Cao Rong Fan Huijun Kang Wanxia Huang Qingxi Yuan Tiqiao Xiao Yanan Fu Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China School of Chemical Engineering Dalian University of Technology Dalian 116024 China School of Automotive Engineering Dalian University of Technology Dalian 116024 China Beijing Synchrotron Radiation Facility Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201204 China

In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification could effectively enhance the grain nucleation and inhibit its growth. Imaging of comparative experiments with varying DC intensity indicated that the final grain size, determined by the competition between grain nucleation and growth, was sensitively dependent on the DC intensity. It was found that the average grain size was decreased from 1632 to 567 μm with DC density of 1.5 A/mm^2 compared to the case without DC. Beyond this value, raising the current density may cause a significant decrease in the nucleation rate, and thus lead to a coarsening of the grain structure.

关键词： Sn-Pb alloy Synchrotron X-ray radiography Solidification Microstructure electric current

Spin and Charge currents through a Quantum Dot Connected to Ferromagnetic Leads

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2005年第8期22卷 2035-2038页

作者：迟锋李树深 StateKeyLaboratoryforSuperlatticesandMicrostructures InstituteofSemiconductorsChineseAcademyofSciencesPOBox912Beijing100083

We investigate the spin polarized current through a quantum dot connected to ferromagnetic leads in the presence of a finite spin-dependent chemical potential. The effects of the spin polarization of the leads p and the external magnetic field B are studied. It is found that both the magnitude and the symmetry of the current are dependent on the spin polarization of the leads. When the two ferromagnetic leads are in parallel configuration, the spin polarization p has an insignificant effect on the spin current, and an accompanying charge current appears with the increase of p. When the leads are in antiparallel configuration, however, the effect of p is distinct. The charge current is always zero regardless of the variation of p in the absence of B. The peaks appearing in the pure spin current are greatly suppressed and become asymmetric as p is increased. The applied magnetic field B results in an accompanying charge current in both the parallel and antiparallel configurations of the leads. The characteristics of the currents are explained in terms of the density of states of the quantum dot.

关键词： TUNNEL-JUNCTIONS DEPENDENT TRANSPORT COHERENT TRANSPORT COULOMB-BLOCKADE MAGNETORESISTANCE OSCILLATIONS BARRIER DEVICE charged currents currents Tunnel junctions electric current Magnetoresistance Coulomb blockade Spin Quantum dots Oscillations Spin polarization water currents exterior magnetic field

A New Discharge Scheme of a Prepulse Plus Two Main Pulses for Capillary-Discharge Soft-X-Ray Laser

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2007年第6期24卷 1580-1582页

作者：栾伯晗赵永蓬王骐程元丽谢耀 National Key Laboratory of Tunable Laser Technology Harbin Institute of Technology Harbin 150001

Reducing the capillary-discharge current is one way of possibly decreasing the pumping power requirement. We examine the influence of various discharge currents on laser intensity and determine the suitable pre-discharge condition for a 46.9-nm discharge-pumped Ne-like Ar soft-x-ray amplifier. The experimental results show that a high additional pre-pulse current at amplitude of several kA and with a very short duration of several tens of nanosecond can effectively decrease the amplitude of the main discharge current at the lasing time. We propose a new discharge scheme of a pre^pulse plus two main pulses which appears to significantly decrease the requirement for discharge current. This in turn may decrease the pumping power requirement for the capillary discharge laser and can greatly increase laser efficiency.

关键词： MAINS Scheme power requirement currents Discharge (fluid mechanics) electric current Amplitude Pumping one way laser efficiency short duration DISCHARGE current Laser