• Title/Summary/Keyword: Porous metal

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Property analysis of polysilane precursors and applications for polysilicon (폴리실란으로부터 생성한 폴리실리콘의 물성 분석과 응용)

  • Lee, Gyu-Hwan
    • Analytical Science and Technology
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    • v.25 no.6
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    • pp.345-349
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    • 2012
  • Polysilane black powders were synthesized by sonochemical methods from silicon tetrachloride with sodium metal with 37.0% yield. Those black powder materials were found to have fibrous or irregular shapes with round surface. It was found that thermal behaviors of those polysilane black powders were similar to that of hydropolysilanes which was reported earlier. After thermal treatment, black polysilicon was obtained with 57.1% residue yield, and those fibrous or irregular shapes with round surface were intact but lots of small cavities were formed indicating porous structure, and found to be an amorphous state from XRD analysis.

The Characteristics Evaluation of the Gas Diffusion Layer for a PEM Fuel Cell by Computational Fluid Dynamics (CFD 해석을 이용한 PEMFC 용 기체확산층의 특성평가)

  • Kim B.H.;Choi J.P.;Jeon B.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.207-210
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    • 2005
  • In this paper, a two-dimensional cross-channel model was applied to investigate influence of the gas diffusion layer(GDL) property and flow field geometry in the anode side for proton exchange membrane fuel cell(PEMFC). The GDL is made of a porous material such as carbon cloth, carbon paper, or metal wire mesh. To the simplicity, the GDL is represented as a block of material containing numerous pathways through which gaseous reactants and liquid water can pass. The purpose of present work was to study the effect of the GDL thickness and the porosity, and flow field geometry by computational fluid dynamics(CFD)

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Synthesis of TCO-less Solar Cell using Metal Mesh Type Electrode and its Photovoltaic Characteristics (금속 메쉬 전극을 이용한 TCO-less 광전변환소자 제작 및 광전변환 특성)

  • Park, Min-Woo;Sung, Youl-Moon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.2
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    • pp.126-130
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    • 2011
  • Transparent conductive oxide (TCO) is an important part in the construction of dye-sensitized solar cells (DSCs) because of its low sheet resistance, sufficient light transparent ability and high photoelectrical response as a porous photo-electrode material of DSCs. However, the use of TCO for the two DSC electrodes can result in significant cost increase for the less effective DSCs compared to Si based solar cell. Therefore, the replacement of TCO is required for the commercial production of DSCs. In this study, TCO electrodes are replaced by stainless steel mesh. The 3.44[%] efficiency of the prepared TCO-less DSCs sample was obtained.

High-Temperature Oxidation Behavior of Commercial Pure Titanium in Mixed Gases (혼합가스 분위기 중에서 공업용 순 타이타늄의 고온산화 거동)

  • Park, S.H.;Ahn, Y.S.
    • Journal of Power System Engineering
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    • v.11 no.2
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    • pp.44-50
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    • 2007
  • The oxidation behavior of commercial pure titanium is investigated in the temperature range of $727^{\circ}C{\sim}950^{\circ}C$ in mixed gases. The weight change is measured by TGA during oxidation in mixed gases. The oxidation behavior indicated by weight gain or the growth of oxide layer is based on the linear rate law at high temperatures. The structure of the oxide scale formed during oxidation is analysed by optical microscopy, electron probe microanalyzer, scanning electron microscope and x-ray diffraction. Oxide scales have a $TiO_2$ structure, and are constituted with multi-layered or two layered porous external one and a dense internal one. Ti-O solid solution region is formed at the interface of metal and scale layer. The formation of oxide scale is influenced by the oxidation temperature, time, crystal structure and the condition of atmosphere.

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Microstructure and Wear Characteristics of Nickel Reinforced AC8A Composites

  • Kim, Hyung-Jin;Tulugan, Kelimu;Park, Won-Jo
    • Journal of Power System Engineering
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    • v.19 no.1
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    • pp.50-55
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    • 2015
  • This study takes AC8A, which is a representative light weight alloy as matrix, and nickel as reinforcement for its superior properties. The manufacturing method applied in this study required low pressure for the infiltration of the metal matrix into the reinforcement. Porous Ni was applied as preform. The fabrication was conducted under 0.3 MPa at 600, 700 and 750 degrees centigrade, respectively. Intermetallic compounds Al3 generated between Al and Ni were observed in the composites. Microstructure, Vickers' hardness and wear characteristics of the composites were also investigated. The result indicates that the structures of compounds created at 650 degree centigrade were distributed densely; the grain size of the substances and the compounds was increased with the infiltration temperature.

Weak Interactions Between Organic Molecules and Alkali Metal Ions Present in Zeolites Help Manipulate the Excited State Behavior of Organic Molecules

  • Ramamurthy, V.
    • Journal of Photoscience
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    • v.10 no.1
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    • pp.127-148
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    • 2003
  • Zeolite is a porous highly interactive matrix. Zeolitic cations help to generate triplets from molecules that possess poor intersystem crossing efficiency. Certain zeolites act as electron acceptors and thus can spontaneously generate radical cations. Zeolites also act as proton donors and thus yield carbocations without any additional reagents. These reactive species, radical cations and carbocations, have long lifetime within a zeolite and thus lend themselves to be handled as ‘regular’ chemicals. Internal structure of zeolites is studded with cations, the counter-ions of the anionic framework. The internal constrained structure and the cations serve as handles for chemists to control the behavior of guest molecules included within zeolites.

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Reduction of Gaseous Acetone by using TiO2 Coated Woven Filters (TiO2 담지 세라믹 필터를 활용한 아세톤 제어에 관한 연구)

  • 윤정호;박덕신;이주열;조영민
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.1
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    • pp.85-92
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    • 2003
  • A new type of catalytic filers has been developed in this work. A porous photocatalytic filter was prepared by coating the titania (anatase phase) powder onto the woven metal mesh. The coating sol was prepared with unique cera-mic binder, and would assist drying condition and enhance the mechanical strength of the final ceramic filers. As a result of the test for acetone decomposition, it was found to be quite effective for the photocatalytic reaction as good at conventional glass reactors which were coated inside. The present filter type reactor is expected as one of plausible devices for the simultaneous treatment of gas - particulate materials.

Characteristics of Spodumene Powders Synthesized by Polyvinyl Alcohol Solution Technique (Polyvinyl Alcohol 폴리머 용액법으로 합성한 스포듀민 분말의 특성연구)

  • Lee, Sang-Jin;Park, Ji-Eun
    • Journal of Powder Materials
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    • v.18 no.1
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    • pp.35-40
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    • 2011
  • LAS-system ceramic powder, spodumene ($Li_2O{\cdot}Al_2O_3{\cdot}4SiO_2$), was successfully synthesized by a chemical solution technique employing PVA(polyvinyl alcohol) as an organic carrier. The PVA content affected the microstructure of porous precursor gels and the crystalline development. The optimum PVA content contributed to homogeneous distribution of metal ions in the precursor gel and it resulted in the synthesis of glass free $\beta$-spodumene powder having a specific surface area of $7.57\;m^2/g$. The agglomerated $\beta$-spodumene powders were also enough soft to grind to fine powders by a simple ball milling process. The microstructures of the densified powder compacts were strongly dependant on the minor phases of spodumene solid solution and amount of liquid phase, which were formed from the inhomogeneous precursors.

Preperation of catalyst having high activity on oxygen reduction (저온형 연료전지용 산소의 고활성 환원 촉매 제조)

  • 김영우;김형진;이주성
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1992.11a
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    • pp.39-40
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    • 1992
  • This paper dealt with the manufacturing of binary alloy catalyst and showed simple electrochemical method for determing catalytic activity of oxygen reduction in acid or alkaline electrolyte. The catalyst was prepared by impregnating transition metal salts on platinum or silver particles adsorbed before on carbon paper substrate. The electrochemical characteristics of the catalysts was investigated with carbon paper electrode or PTFE-boned porous electrode and then cathodic current densities and tafel slopes were compared. As a result, of all binary catalysts utilized in this work, Pt-Fe, Pt-Mo showed better oxygen reduction activity than pure platinum catalyst in acid electrolyte and Ag-Fe, Ag-Pt, and Ag-Ni-Bi-Ti catalyst did than pure silver catalyst in alkaline electrolyte. The current density of Pt-Fe electrode in acid electrolyte was one and half times higher than that of Pt electrode(~500mA/$\textrm{cm}^2$ at 0.7VvsNHE).

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A numerical method for dynamic characteristics of nonlocal porous metal-ceramic plates under periodic dynamic loads

  • Abdulrazzaq, Mohammed Abdulraoof;Kadhim, Zeyad D.;Faleh, Nadhim M.;Moustafa, Nader M.
    • Structural Monitoring and Maintenance
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    • v.7 no.1
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    • pp.27-42
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    • 2020
  • Dynamic stability of graded nonlocal nano-dimension plates on elastic substrate due to in-plane periodic loads has been researched via a novel 3- unknown plate theory based on exact position of neutral surface. Proposed theory confirms the shear deformation effects and contains lower field components in comparison to first order and refined 4- unknown plate theories. A modified power-law function has been utilized in order to express the porosity-dependent material coefficients. The equations of nanoplate have been represented in the context of Mathieu-Hill equations and Chebyshev-Ritz-Bolotin's approach has been performed to derive the stability boundaries. Detailed impacts of static/dynamic loading parameters, nonlocal constant, foundation parameters, material index and porosities on instability boundaries of graded nanoscale plates are researched.