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The effect of diluent gases on the growth of β-SiC films by laser CVD with HMDS

materials Research Innovations 2015年 19卷 403-407页

作者： Zhu, P.P. Tu, R. Zhang, S. Han, M.X. Xu, Q.F. Sun, Q.Y. Zhang, L.M. Goto, T. Yan, J.S. Li, S.S. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology 122 Luoshi Road Wuhan430070 China Institute for Materials Research Tohoku University 2-1-1 Katahira Aoba-ku Sendai980-8577 Japan Tech Semiconductors Ltd Xiangyang441000 China

β-SiC films have been fabricated on (100) Si substrates by laser chemical vapour deposition using hexamethyldisilane ((CH3)3-Si-Si-(CH3)3) as a source precursor while argon or hydrogen as a diluent gas, respectively. The effects of different diluent gases species on the microstructure and deposition rate have been investigated by varying the flow rate of hexamethyldisilane (fHMDS). The results showed that pyramid, flower and needle-like morphologies were obtained using argon as diluent gas, whereas only pyramid with little flower structure appeared in the case of hydrogen. The deposition rate (Rdep) was in proportion to the fHMDS irrespective of diluent gases. Rdep was nearly 50% higher for hydrogen as diluent gas. © 2015 W. S. Maney & Son Ltd.

关键词： Microstructure

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RESEARCH ON VIBRATION CHARACTERISTICS OF POROUS RECTANGULAR HEXAHEDRON SONOTRODE

RESEARCH ON VIBRATION CHARACTERISTICS OF POROUS RECTANGULAR ...

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2015全国压电和声波理论及器件技术研讨会

作者： Kai LI Guang-chao HAN Gao-feng PAN Zhuo PENG Faculty of Mechanical & Electronic Information China University of Geosiences State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology

Rectangular hexahedron sonotrode has remarkable advantage as a platform to realize auxiliary ultrasonic vibration of workpiece with its abundant resonant ***,the three-dimensional coupled vibration characteristics of rectangular hexahedron sonotrode is hard to meet the requirement of ultrasonic assisted micro forming process,which should be made structural optimization for improving its vibration *** this paper,the basic structure of 20kHz rectangle hexahedron sonotrode was designed according to the apparent elastic method and R-L square transformer design *** influence of number,size and distribution of inner holes and structure transition arc radius was simulated analysed for optimizing the vibration properties of the *** results show that the optimized rectangular hexahedron sonotrode can realize the conversion of ultrasonic vibration direction and get uniform vertical vibration amplitude on the whole radiant surface,so as to meet the requirement of ultrasonic assisted micro forming processing.

关键词： Porous sonotrode Rectangular hexahedron Vibration characteristics Simulation analysed

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Effect of 2,2′-dipyridyl on the plating rate, microstructure and performance of copper-coated tungsten composite powders prepared using electroless plating

Effect of 2,2′-dipyridyl on the plating rate, microstructur...

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作者： Chen, Wenshu Luo, Guoqiang Li, Meijuan Shen, Qiang Wang, Chuanbin Zhang, Lianmeng State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Highly pure copper-coated tungsten powders were successfully prepared in fixed quantities using electroless plating, via the addition of an appropriate amount of 2,2′-dipyridyl to the plating bath. The effect of 2,2′-dipyridyl on the plating Cu rate, microstructure and performance of the coated Cu layer was studied systematically. Changing the concentration of 2,2′-dipyridyl had significant effects on the plating Cu rate, surface morphology, average grain size, purity and quantity of coated Cu. With a 2,2′-dipyridyl concentration of approximately 20-40 mg/L, the coated Cu was highly pure, with very little oxygen content (less than 0.1 wt.%). The complexation of the 2,2′-dipyridyl with cuprous ions and the absorption of the 2,2′-dipyridyl on the coated Cu surface can explain these findings. With increase in the concentration of 2,2′-dipyridyl in the plating bath, the plating Cu rate, microstructure and performance of the coated Cu layer changed steadily, indicating that the complexation and absorption of 2,2′-dipyridyl gradually approached a saturation level. High thermal performance W-Cu composite can be fabricated by using these composite powders. © 2014 Published by Elsevier B.V.

关键词： Electroless plating

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Effect of flow-field dimensions on the formability of Fe-Ni-Cr alloy as bipolar plate for PEM Fuel Cell 20

Effect of flow-field dimensions on the formability of Fe-Ni-...

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20th World Hydrogen Energy Conference, WHEC 2014

作者： Hu, Qinghui Zhang, Dongming Fu, Hao State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China

The Fe-Ni-Cr alloy is a potential material as bipolar plate for proton exchange membrane fuel cell, and the stamped metal bipolar plate is a promising candidate for the traditional graphite due to the advantages of mass production, low cost and excellent performance. The flow-channel geometrical dimensions, including channel width, rib width, channel depth, draft angle and radius of the fillet, have vital influences on the formability of the alloy during the stamping process. This paper numerically investigates how the serpentine flow-field geometrical dimensions affect the formability of the alloy plate by the finite element software. The finite element model was established with different channel dimensions in this study. The results predict the proper scope of flow-field dimension for alloy used for bipolar plate, further, the stamping process of alloy plate is also optimized to obtain better performance.

关键词： Proton exchange membrane fuel cells (PEMFC)

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Fabrication and properties of W-Cu functionally graded material by tape-casting

Fabrication and properties of W-Cu functionally graded mater...

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5th International Symposium on advanced Ceramics, ISAC 2013 and 3rd International Symposium on advanced synthesis and processing technology for materials, ASPT 2013

作者： Luo, Guoqiang Dai, Yang Liu, Shulong Yu, Kan Shen, Qiang Zhang, Lianmeng State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

ISBN: (纸本)9783038351306

In this paper, the W-Cu functionally graded material (FGM) was prepared by using the non- Aqueous tape-casting technique combined with vacuum hot-pressing sintering. The graded composite material with high density, uniform transition and graded component was designed by 7 layers with the copper content range from 40 to 100 wt. %. Then the structures and properties of the composite were characterized. The scanning acoustic microscope (SAM) results for the W-Cu graded material showed that the interface between different layers was of high smoothness and parallel. The SEM-EDS results of cross section show that the W and Cu content changed gradually along the laminating direction after sintering. The equivalent electrical conductivity and the equivalent thermal conductivity of the W-Cu graded material were 0.3976×108 S/m and 323.5 W/(m·K), respectively, which were much higher than that of the W-40 wt. % Cu homogeneous composite. The Vickers hardness of the high tungsten content surface and the high copper surface were 163 HV and 80 HV, respectively, which were same with that of the homogeneous material. © (2014) Trans Tech Publications, Switzerland.

关键词： Functionally graded materials

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Investigation of stamping process of metallic bipolar plates in PEM fuel cell - Numerical simulation and experiments

Investigation of stamping process of metallic bipolar plates...

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作者： Hu, Qinghui Zhang, Dongming Fu, Hao Huang, Kaikai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Flow channel in bipolar plate for PEMFC has the function of transporting the fuel and oxygen and water. Stamping process for flow channel on metallic bipolar plates is an economic and convenient method for mass production. It is extremely important to predict and prevent the tearing, wrinkling, thinning, skid mark and spring back in stamping process. In this study, finite element method is used to predict the imperfection and analyze thickness variation during the stamping process. Dynaform software is employed to predict the performance of a stamping process. Forming Limit Diagrams are used to determine the safe limit of the metallic bipolar plates. In simulation, the dimension of flow channels, punch speed, radius of punch and die and draft angle were selected as variable process parameters. Experiments were conducted to compare with the simulation results. It is demonstrated that the simulation results are in good agreement with the experimental ones for ss304 metal sheets. So simulation model could be employed as a predictive tool to provide optimal parameters for better performance of the stamping process. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Skids

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The activity influence of isopropyl alcohol for flat plant Pt and Pt/C electrode

The activity influence of isopropyl alcohol for flat plant P...

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2014 Electrochemical Conference on Energy and the Environment, ECEE 2014

作者： Sun, Shuang Pan, Mu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China

ISBN: (纸本)9781607685555

Pt, as a precious metal, is an important component of fuel cell catalyst, however the impurities in polymer electrolyte membrane fuel cell(PEMFC) has a great influence on the electrochemical activity. This paper studies the electrochemical activity influence of isopropyl alcohol(IPA) on a flat plate Pt and Pt/C electrodes by means of cyclic voltammograms and oxygen reduction test methods, the influence of the research results show that the addition of isopropyl alcohol will not change the stripping potentials of hydrogen, but it will obviously block the absorption of proton at the Hads potentials, and the biggest oxidation current on the Pt/C electrode was larger than that on the flat plate Pt electrode;we also find that the present of IPA reduces the limit current density of the plate Pt electrode, thus further influence on the performance of the catalyst in PEMFC. © The Electrochemical Society.

关键词： Proton exchange membrane fuel cells (PEMFC)

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Research on phase-field model of three-dimensional dendritic growth for binary alloy

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Journal of Computational and Theoretical Nanoscience 2015年第11期12卷 4289-4296页

作者： Feng, Li Jia, Jinfang Zhu, Changsheng Lu, Yang Xiao, Rongzhen Wang, Zhiping College of Materials and Engineering Lanzhou University of Technology Lanzhou730050 China State Key Laboratory of Gansu Advanced Processing and Recycling of Non-Ferrous Metal Lanzhou730050 China

Based on the three-dimensional phase-field model (KKS model) of single-phase system and pure diffusion dendritic growth for binary alloy, the normal vector of dendritic solid-liquid interface migration direction is employed as an independent variable to describe phase-field governing function and interfacial free energy anisotropy equation, and the angle between the normal direction of dendritic growth interface migration and the optimal growth direction is used to describe interfacial free energy anisotropy function, and the purpose is to improve phase-field model. Taking Al-Cu binary alloy for example, the three-dimensional dendritic growth with different growth orientations and the dendritic tip growth velocities under different undercoolings are simulated. The simulation results are compared with the KKS model's simulation results and the predicted results of the classical solidification theory (LKT (BCT) theory). The results show that the simulation results agree well with the theoretical prediction results. The definitional domains of three angle variables in the interfacial free energy anisotropy function used this paper research are the same and there is a one-to-one relationship among them, and then the numerical simulation of solid-liquid interface evolution about different grains' common growth with different optimal growth orientations is realized. © 2015 American Scientific Publishers.

关键词： Binary alloys

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Effects of the Interaction between Hydroxyapatite Nanoparticles and Hepatoma Cells

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Journal of Wuhan University of technology(materials Science) 2014年第3期29卷 635-642页

作者：尹美珍 XU Weiguo CUI Bingcun 戴红莲 HAN Yingchao YIN Yixia LI Shipu School of Medicine Hubei Polytechnic University Tongji Hospital Tongji Medical College Huazhong University of Science and Technology State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Biomedical Materials and Engineering Center Wuhan University of Technology

To gain a better understanding of the anticancer effects of hydroxyapatite （HAP） nanoparticles in vivo and in vitro, the effects of the interaction of HAP nanoparticles with hepatoma cells were explored. HAP nanoparticles were prepared by homogeneous precipitation and characterized by laser particle analysis and transmission electron microscopy （TEM）. HAP nanoparticles were observed to be uniformly distributed, with rod-like shapes and diameters in the range of 42.1-87.1 nm. Overnight attached, suspended, and proliferating Bel-7402 cells were incubated with HAP nanoparticles. Inverted microscopy observation revealed that HAP nanoparticles with a cell membrane showed good adsorption. TEM demonstrated that HAP nanoparticles were present on the surface of cells, continuously taken up by cells through endocytosis, and transported in vesicles close to the nucleus. Fluorescence microscopy showed that the concentrations of intracellular Ca2＋ labeled with Fluo-3 calcium fluorescent probe were significantly enhanced. In addition, inverted microscopy observation revealed that suspended cells treated with HAP nanoparticles did not adhere to the culture bottle, resulting in cell death. After the overnight attached cells were treated with HAP nanoparticles for 96 h with increasing doses of HAP nanoparticles, inverted microscopy observation revealed that cell proliferation was slowed and ceU-ceU adhesion was weakened. Feulgen staining and image analysis indicated that the nuclear DNA content of the cells was markedly reduced, and argyrophilic nucleolar organizer region （AgNOR） staining and image analysis indicated that the number of AgNORs was significantly decreased. Therefore, hepatoma cells brought about the adsorption, uptake, transport and degradation of HAP nanoparticles. In addition, HAP nanoparticles affected hepatoma cells with regard to cell-cell adhesion, cell and extracellular matrix adhesion, and DNA and protein synthesis; thus inhibiting cell proliferation. This und

关键词： hydroxyapatite nanoparticles hepatoma cells interaction effects cell adhesion

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Microstructure of stress-induced martensite in nanocrystalline NiTi shape memory alloy

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Rare Metals 2014年第4期33卷 379-382页

作者： Xiao-Bin Shi Li-Shan Cui Zhen-Yang Liu Da-Qiang Jiang Xiao-Dong Han State Key Laboratory of Heavy Oil Processing China University of Petroleum Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology

The microstructure of stress-induced martensite （SIM） in the nanocrystalline NiTi alloy was investigated by means of transmission electron microscopy （TEM）. The result shows that the multi-variant structure of the martensite is suppressed and only single-variant martensitic twins form after tensile deformation when the grain size is smaller than 80 nm. The normal directions of the （001）B19, twin planes are all. within the range of 45° from the axial direction of the wire. The angle between twin crystals （111）M and （111）x of the SIM is also found to be smaller than that of thermally induced martensite in nanocrystalline NiTi.

关键词： Martensitic transformation Microstructure Shape memory alloys Twin

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