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The electrical switching characteristics of single copper tetra-cyanoquinodimethane nanowire

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nano-Micro letters 2009年第1期1卷 23-26页

作者： K.B.Zheng h.T.Shen C.n.Ye j.l.li D.l.Sun G.R.Chen Department of Materials Science Fudan University Department of Materials Science and Engineering Soochow University

In this paper, method combined vapor transportation with in-situ chemical reaction is employed to synthesize Cu(TCnQ) nanowires. The typical diameter of nanowires is 50-500 nm with high uniformity. The electrical switching characteristics of single nanowire are observed. The On-OFF resistance ratio for switching reaches 10~4. The investigation reveals a linear relationship between the switching threshold and the spacing between the two electrodes. The temporal response of the switching process is 30 ns and the switch exhibits good reproducibility. The collapse of the nanowire under the condition of current surge is also discussed. It is believed that the Cu(TCnQ) nanowire could be promising for applications in nanoelectronics.

关键词： Cu(TCnQ) nanowire Electrical switching Charge transfer Complexes

Comparative methane estimation from cattle based on total CO_2 production using different techniques

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Animal nutrition 2017年第2期3卷 175-179页

作者： Md n.haque hanne h.hansen Ida M.l.D.Storm jφrgen Madsen Department of large Animal Sciences Faculty of Health and Medical SciencesUniversity of Copenhagen

The objective of this study was to compare the precision of Ch4 estimates using calculated CO_2(hP) by the CO_2 method(CO_2 T) and measured CO_2 in the respiration chamber(CO_2 R). The CO_2 R and CO_2 T study was conducted as a 3 × 3 latin square design where 3 Dexter heifers were allocated to metabolic cages for 3 periods. Each period consisted of 2 weeks of adaptation followed by 1 week of measurement with the CO_2 R and CO_2 T. The average body weight of the heifer was 226 ± 11 kg(means±SD). They were fed a total mixed ration, twice daily, with 1 of 3 supplements: wheat(W), molasses(M), or molasses mixed with sodium bicarbonate(Mbic). The dry mater intake(DMI: kg/day) was significantly greater(P n the metabolic cage compared with that in the respiration chamber. The daily Ch4(l/day) emission was strongly correlated(r=0.78) between CO_2 T and CO_2 R. The daily Ch4(l/kg DMI) emission by the CO_2 T was in the same magnitude as by the CO_2 R. The measured CO_2(l/day) production in the respiration chamber was not different(P = 0.39) from the calculated CO_2 production using the CO_2 T. This result concludes a reasonable accuracy and precision of Ch4 estimation by the CO_2 T compared with the CO_2 R.

关键词： Carbon dioxide Precision Methane Measurement Respiration chamber

Different Diffusion Behavior of Cu and ni Undergoing liquidesolid Electromigration

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journal of Materials Science & Technology 2014年第12期30卷 1235-1242页

作者： M.l.huang Z.j.Zhang h.T.Ma l.D.Chen Electronic Packaging Materials laboratory School of Materials Science & Engineering Dalian University of Technology IC Packaging Department Xi'an Institute of Microelectronic Technology

The diffusion behavior of Cu and ni atoms undergoing liquidesolid electromigration（l-S EM） was investigated using Cu/Sn/ni interconnects under a current density of 5.0 103A/cm2 at 250℃. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and ni atoms, i.e., under downwind diffusion, both Cu and ni atoms can diffuse to the opposite interfaces; while under upwind diffusion,Cu atoms but not ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the ni, only Cu atoms diffuse to the opposite anode ni interface, resulting in the transformation of interfacial intermetallic compound（IMC） from ni3Sn4into（Cu,ni）6Sn5and further into [（Cu,ni）6Sn5t Cu6Sn5], while no ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 *** electrons flow from the ni to the Cu, both Cu and ni atoms diffuse to the opposite interfaces,resulting in the interfacial IMC transformation from initial Cu6Sn5into（Cu,ni）6Sn5and further into[（Cu,ni）6Sn5t（ni,Cu）3Sn4] at the anode Cu interface while that from initial ni3Sn4into（Cu,ni）6Sn5and further into（ni,Cu）3Sn4at the cathode ni interface. It is more damaging with electrons flowing from the Cu to the ni than the other way.

关键词： Cu/Sn/ni Electromigration Cross-solder interaction Interfacial reaction Diffusion

Application of a new reagent for analysis of oxygen presence in a lowcarbon steel wire rod

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journal of Iron and Steel Research International 2021年第6期28卷 729-738页

作者： M.I.Dávila-Pérez h.j.Vergara-hernández O.Vázquez-Gómez F.Reyes-Calderón E.lópez-Martínez j.M.Salgado-lópez national Technology of Mexico/T.I.of Morelia Morelia 58120MichoacanMexico national Council for Science and Technology COnACYT Mexico City 03940Mexico Isthmus University Santo Domingo TehuantepecOaxaca 70760Mexico Engineering and Industrial Development Center CIDESI Santiago de Queretaro 76125QueretaroMexico

A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire *** failure zone was analyzed by comparison using three different attack reagents:alkaline sodium chromate(ASC),ASC with hydrogen peroxide and amyl alcohol,and a solution of nitric acid in ethyl *** reagents were applied in samples in the failure zone,showing different types of zones in regions with internal and superficial defects such as carbides,pores,cracks,deformation,and detachment zones,indicating the possible presence of *** areas identified were observed by means of an optical microscope and were correlated with the content of elements that were present in the region using a scanning electron microscope and a scattered X-ray energy spectrometer,which determined that the areas identified by chromate sodium correspond to regions with a high concentration of oxygen and slag-forming elements such as silicon,aluminum,and iron;this is associated with the presence of oxygen in the oxide *** was also observed that the ASC and the modified ASC solution with hydrogen peroxide and amyl alcohol could identify areas with a high presence of oxides,while the nitric acid solution only identified the steel *** modified ASC solution is an alternative to identify the presence of chemical variants of oxygen because the conventional formulation is unstable and has a too short shelf life,and therefore,its application must be carried out at the time of preparation.

关键词： Etching Alkaline sodium chromate Oxide presence Internal defect

Achieving ultra-high strength friction stir welded joints of high nitrogen stainless steel by forced water cooling

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journal of Materials Science & Technology 2018年第11期34卷 2183-2188页

作者： h.Zhang D.Wang P.Xue l.h.Wu D.R.n B.l.Xiao Z.Y.Ma Shenyang national laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China University of Chinese Academy of Sciences 19 Yuquan RoadBeijing 100049China

The microstructure and properties of water-cooled and air-cooled friction stir welded（FSW） ultra-high strength high nitrogen stainless steel joints were comparatively studied. With additional rapid cooling by flowing water, the peak temperature and duration at elevated temperature during FSW were significantly reduced. Compared to those in the air-cooled joint, nugget zone with finer grains（900 nm） and heat affected zone with higher dislocation density were successfully obtained in the water-cooled joint,leading to significantly improved mechanical properties. The wear of the welding tool was significantly reduced with water cooling, resulting in better corrosion resistance during the immersion corrosion test.

关键词： Friction stir welding Stainless steels Mechanical properties Corrosion

Extension/Compression-Controlled Complete Band Gaps in 2D Chiral Square-lattice-like Structures

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Acta Mechanica Solida Sinica 2018年第1期31卷 51-65页

作者： Y. l. huang n. Gao W.Q. Chen R.h. Bao Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China State Key lab of CAD & CG Zhejiang University Hangzhou 310058 China Key laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Hangzhou 310027 China Soft Matter Research Center Zhejiang University Hangzhou 310027 China

Achieving tunable band gaps in a structure by external stimuli is of great importance in acoustic applications. This paper aims to investigate the tunability of band gaps in square-lattice-like elastic periodic structures that are usually not featured with notable band gaps. Endowed with chirality, the periodic structures here are able to undergo imperfection-insensitive large deformation under extension or compression. The influences of geometric parameters on band gaps are discussed via the nonlinear finite element method. It is shown that the band gaps in such structures with curved beams can be very rich and, more importantly, can be efficiently and robustly tuned by applying appropriate mechanical loadings without inducing buckling. As expected, geometry plays a more significant role than material nonlinearity does in the evolution of band gaps. The dynamic tunability of band gaps through mechanical loading is further studied. Results show that closing, opening, and shifting of band gaps can be realized by exerting real-time global extension or compression on the structure. The proposed periodic structure with well-designed chiral symmetry can be useful in the design of particular acoustic devices.

关键词： Band gap Tunability Square-lattice-like periodic structure Chiral symmetry,large deformation

Effects of temperature on the tribological behavior of Al0.25CoCrFeni high-entropy alloy

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journal of Materials Science & Technology 2019年第5期35卷 917-925页

作者： l.M.Du l.W.lan S.Zhu h.j.Yang X.h.Shi P.K.liaw j.W.Qiao Research Center for high-Entropy Alloys College of Materials Science and Engineering Taiyuan University of Technology Taiyuan 030024 China national Key laboratory for Remanufacturing Academy of Armored Forces Engineering Beijing 100072 China Department of Materials Science and Engineering The University of Tennessee Knoxville TN 37996-2200 USA

The tribological behavior of Al0.25 CoCrFeni high-entropy alloy(hEA) sliding against Si3n4 ball was investigated from room temperature to 600°. The microstructure of the alloys was characterized by simple FCC phase with 260 hV. Below 300°, with increasing temperature, the wear rate increased due to high temperature softening. The wear rate remained stabilized above 300°due to the anti-wear effect of the oxidation film on the contact interface. The dominant wear mechanism of hEA changed from abrasive wear at room temperature to delamination wear at 200°, then delamination wear and oxidative wear at 300°and became oxidative above 300°. Moreover, the adhesive wear existed concomitantly below 300°.

关键词： Abrasive wear Friction and wear characteristics hardness high temperature Microstructure Oxidation Rapid solidification Sliding Wear mechanism

FInITE ElEMEnT nUMERICAl SIMUlATIOn OF TEMPERATURE FIElD In METAl PATTERn CASTInG SYSTEM AnD "REVERSE METhOD" OF DEFInInG ThE ThERMAl PhYSICAl COEFFICIEnT

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Acta Metallurgica Sinica(English letters) 2007年第3期20卷 217-224页

作者： l. Chen P.l. Wang P.n. Song j.Y. Zhang Mechanical Engineering College Tianjin University of Technology Tianjin 300191China

With the technology support of virtual reality and AnSYS software, an example on the simulation of temperature distribution of casting system during the solidification process was provided, which took the latent heat of phase change, the conditions for convection, and the interface heat transfer coefficient into consideration. The result of AnSYS was found to agree well with the test data. This research offers an unorthodox way or ＂reverse method＂ of defining the relevant thermal physical coefficient.

关键词： solidification process reverse method AnSYS software

Effect of Solidification Condition and Carbon Content on the Morphology of MC Carbide in Directionally Solidified nickel-base Superalloys

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journal of Materials Science & Technology 2014年第12期30卷 1296-1300页

作者： X.W.li l.Wang j.S.Dong l.h.lou Superalloys Division Institute of Metal Research Chinese Academy of Sciences

Evolution of the morphology of MC carbides with the change of cooling rate and carbon content in two kinds of nickel-base superalloys, K417 G and DD33, has been investigated. The morphology of MC carbides evolves from faceted to script-like with increasing cooling rate. Varying the carbon content from 40X10-6 to 320X10-6, the morphology of carbides changes from blocky, rod-like into script-like. Scanning electron microscopy observation of deep-etched samples indicates that these carbides evolve from octahedral to dendritic and then into welldeveloped dendrites accordingly in a three-dimensional manner. The morphology evolution is discussed from the viewpoint of the preferential growth orientation of fcc crystals and the carbide growth rate during directional solidification.

关键词： Carbides morphology Directional solidification Three-dimensional microstructure nickel-base superalloys