• Title/Summary/Keyword: $Mg_2Ni$ based

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Hydrogenation Study of Mg-based Alloys by mechanical Grinding Reaction for Hydrogen Storage of Fuel Cell (연료전지의 수소저장용 마그네슘계 합금의 기계적 분쇄 반응에 의한 수소화 특성 평가)

  • Kim, Ho-Sung;Suh, Hee-Seok;Cha, Jae-Sang
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.6
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    • pp.69-74
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    • 2006
  • The effects of mechanical grinding(MG) treatment on the hydrogen storage of $Mg_2Ni$ alloy and $Mg_2Ni$ composite alloy($Mg_2Ni+graphite$) were investigated by pressure-composition-temperature(PCT) measurement, the micro-electrode technique of electrochemistry and etc, in which PCT was measured at high temperature(around $300[^{\circ}C]$) of gas phase and a carbon-filament micro-electrode for electrochemical evaluation was manipulated to make electrical contact with the particle in 1M KOH aqueous solution. It was found that the hydrogenation properties of $Mg_2Ni$ and graphite composite particle were greatly improved by the mechanical grinding treatment by which the $Mg_2Ni$ and graphite composite alloys could be changed into microstructure and nano-level particles. namely; the hydrogen dissociation pressure of PCT measurement was decreased from 0.55[MPa] to 0.42[MPa] and hydrogenation peaks by micro-electrode were also observed more clearly on the same sample.

Effect of High Energy Ballmilling on the Discharge Properties of Mg-Ni Based Electrodes (고에너지 볼밀링이 Mg-Ni계 수소저장합금전극의 방전특성에 미치는 영향)

  • Han, Ji-Seong;Kim, Ki-Won;Ahn, In-Shup;Hur, Bo-Yong;Ahn, Hyo-Jun
    • Transactions of the Korean hydrogen and new energy society
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    • v.10 no.1
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    • pp.49-57
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    • 1999
  • In order to study the effect of high energy ball milling on the $Mg_2Ni+Ni$, $Mg_2Ni+0.5Ni+0.5Al$ powders, we have investigated on the discharge properties, microstructures. The powder size of samples decreased as ball milling time. From the XRD results, the crystal structure of $Mg_2Ni+Ni$ mixed powders were changed to amorphous or nano-structure after 60hr ball milling. The discharge capacities of both $Mg_2Ni+Ni$ and $Mg_2Ni+0.5Ni+0.5Al$ powders increased, with increasing ballmilling time, the maximum capacity(342mAh/g) was shown for the 60 hrs ballmilled $Mg_2Ni+Ni$ sample. The capacity decreased drastically after a few charge-discharge cycles.

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Electrical and Dielectric Characteristics of Zn-Pr-Co-Dy-M(M=Ni, Mg, Cr) Oxides-Based Varistors (Zn-Pr-Co-Dy-M(M=Ni, Mg, Cr) 산화물계 바리스터의 전기적, 유전적 특성)

  • 남춘우;박종아
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.9
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    • pp.924-929
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    • 2004
  • The microstructure, electrical and dielectric characteristics of $ZnO-{Pr}_6{O}_11-{CoO}-{Dy}_2{O}_3$-based varistors were investigated without and with various metal oxide additives(NiO, MgO, Cr$_2$O$_3$). The average grain size decreased in the range of 18.4 $\backsim$ 11.5 $\mu$m, in order of NiO\longrightarrowMgO\longrightarrow{Cr}_2{O}_3$ and the density decreased in the range of 5.62 \backsim 5.33 $g/{cm}^3$ in order of NiO\longrightarrowCr$_2$O$_3$\longrightarrowMgO. While, the nonlinear exponent increased In the range of 19.8$\backsim$67.4 in order of NiO\longrightarrowMgO\longrightarrow${Cr}_2{O}_3$ and the leakage current decreased in the range of 25.6 $\backsim$ 1.2 $\mu$A in order of NiO\longrightarrow${Cr}_2{O}_3$\longrightarrowMgO. Among all varistors, the Cr$_2$O$_3$-added varistor exhibited the highest nonlinearity, with a nonlinear exponent of 67.4 and a leakage current of 1.2 $\mu$A. Furthermore, this varistor exhibited the lowest dielectric dissipation factor of 0.0407.

Improvement of Mg-based Hydrogen Storage Alloys by Mechanochemical Ball Milling (기계화학적 볼밀링을 이용한 Mg 합금의 수소저장능 향상 연구)

  • 안중호;최영묵
    • Journal of Powder Materials
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    • v.9 no.2
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    • pp.83-88
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    • 2002
  • The mechanochemical milling of Mg and $Mg_2Ni$ alloys were carried out to examine the enhancement of hydrogen storage properties of Mg alloys. The hydroge characteristics of the ball-milled products were evaluated with a Sievert-type apparatus and electrochemical test. Various intermediate compounds were obtained by chemical reactions induced during the ball milling of Mg of $Mg_2Ni$ alloys with C, Ni, $Ni_2Cl$ and $Ca_2Cl$. The system of $Mg_2Ni$ with 10 wt% C improved markedly the kinetics of hydrogen absorption, while the hydrogen capacities were practically unchanged. The hydrogen storage alloys such as Mg-Ca can be successfully.

Fabrication and hydrogen storage property of eutectic Mg-Ni based alloy powder (공정 Mg-Ni계 합금 분말의 제조 및 수소저장 특성)

  • Hong, Seong-Hyeon;Bae, Jong-Soo;Yim, Chang-Dong;Na, Young-Sang;Song, Myoung-Youp
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.2
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    • pp.174-180
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    • 2006
  • The eutectic Mg-23.5%Ni alloy was casted by melting and solidification. The powders of Mg-23.5%Ni and (Mg-23.5%Ni)-10% iron oxide were prepared by mechanical grinding of casted Mg-Ni alloy and casted Mg-Ni alloy+oxide, respectively. As milling time increases, hydriding and dehydriding rates of Mg-Ni and Mg-Ni-oxide alloy powders increase. The additions of iron oxide to Mg-Ni alloy and Mg-Ni-oxide increase hydriding rates and slightly decrease dehydriding rates.

Mass Production of Mg based Hydrogen Absorbing Alloys and Evalution of Hydrogenation and Degradation Properties by Hydriding/Dehydriding Cyclic Test (교반관법에 의한 Mg 기지 수소저항합금의 대량제조와 반복적 수소화 반응에 따른 수소화 특성 및 열화특성 평가)

  • Ha, Won;Lee, Sung-Gon;Hong, Tae-Whan;Kim, Young-Jig
    • Transactions of the Korean hydrogen and new energy society
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    • v.13 no.1
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    • pp.13-23
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    • 2002
  • Hydrogenation properties of Mg-Ni and Mg-Ti-Ni alloys were investigated by Pressure-Composition Isotherm (PCI) test. Those alloys were fabricated by a new alloying method, Rotation-Cylinder Method (RCM). The as-cast microstructure of Mg-10 mass% Ni alloy consists of an island-like hydride forming $\alpha$-Mg phase and the eutectic structure. After 350 cyclic tests, Mg-lO mass % Ni alloy was pulverized into fine particles of 100 nm. The fine particles, which have a large specific surface area, are highly reactive with hydrogen. However, extreme pulvehzation can separate Mg from $Mg_2Ni$ in the eutectic structure, so $Mg_2Ni$ of the eutectic structure cannot behave as a dissociated hydrogen supplier.

Effects of Nickel and Iron Oxide Addition by Milling under Hydrogen on the Hydrogen-Storage Characteristics of Mg-Based Alloys

  • Song, Myoung Youp;Baek, Sung Hwan;Park, Hye Ryoung;Mumm, Daniel R.
    • Korean Journal of Metals and Materials
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    • v.50 no.1
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    • pp.64-70
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    • 2012
  • Samples of pure Mg, 76.5 wt%Mg-23.5 wt%Ni, and 71.5 wt%Mg-23.5 wt%Ni-5 wt%$Fe_2O_3$ were prepared by reactive mechanical grinding and their hydriding and dehydriding properties were then investigated. The reactive mechanical grinding of Mg with Ni is considered to facilitate nucleation and to shorten diffusion distances of hydrogen atoms. After hydriding-dehydriding cycling, the 76.5 wt%Mg-23.5 wt%Ni and 71.5 wt%Mg-23.5 wt%Ni-5 wt%$Fe_2O_3$ samples contained $Mg_2Ni$ phase. In addition to the effects of the creation of defects and the decrease in particle size, the addition of Ni increases the hydriding and dehydriding rates by the formation of $Mg_2Ni$. Expansion and contraction of the hydride-forming materials (Mg and $Mg_2Ni$) with the hydriding and dehydriding reactions are also considered to increase the hydriding and dehydriding rates of the mixture by forming defects and cracks leading to the fragmentation of particles. The reactive mechanical grinding of Mg-Ni alloy with $Fe_2O_3$ is considered to decrease the particle size.

Toxicity Evaluation of Metals and Metal-oxide Nanoparticles based on the Absorbance, Chlorophyll Content, and Cell Count of Chlorella vulgaris (Chlorella vulgaris의 흡광도, 클로로필 및 개체수 통합 영향에 근거한 중금속 및 나노입자 독성 조사)

  • Jang, Hyun Jin;Lee, Mun Hee;Lee, Eun Jin;Yang, Xin;Kong, In Chul
    • Clean Technology
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    • v.23 no.1
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    • pp.27-33
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    • 2017
  • In this study, toxicities of seven metals (Cu, Cd, Cr, As(III), As(V), Zn, Ni) and five metal oxide nanoparticles (NPs: CuO, ZnO, NiO, $TiO_2$, $Fe_2O_3$) were evaluated based on the growth of Chlorella vulgaris. Effect on algae growth was evaluated by integrating the results of absorption, chlorophyll content, and cell count. The toxicity rankings of metals was observed as Cr ($0.7mgL^{-1}$) > Cu ($1.7mgL^{-1}$) > Cd ($3.2mgL^{-1}$) > Zn ($3.9mgL^{-1}$) > Ni ($13.2mgL^{-1}$) > As(III) ($17.8mgL^{-1}$) ${\gg}$ As(V) (> $1000mgL^{-1}$). Slightly different orders and sensitivities of metal toxicity were examined depending on endpoints of algal growth. In case of NPs, regardless of endpoints, similar toxicity rankings of NPs ($TEC_{50}$) were observed, showing ZnO ($2.4mgL^{-1}$) > NiO ($21.1mgL^{-1}$) > CuO ($36.6mgL^{-1}$) > $TiO_2$ ($62.5mgL^{-1}$) > $Fe_2O_3$ ($82.7mgL^{-1}$). These results indicate that an integrating results of endpoints might be an effective strategy for the assessment of contaminants.

Reaction Kinetics with Hydrogen and Temperature Dependence of the Hydriding Rate for a Magnesium-Based Nickel Iron Oxide Alloy

  • Song, Myoung Youp;Baek, Sung Hwan;Park, Hye Ryoung
    • Korean Journal of Metals and Materials
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    • v.50 no.6
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    • pp.463-468
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    • 2012
  • A 71.5 wt%Mg-23.5 wt%Ni-5 wt%$Fe_2O_3$ (Mg-23.5Ni-$5Fe_2O_3$) sample was prepared by a quite simple process, reactive mechanical grinding, and its hydriding and dehydriding properties were then investigated. The reactive mechanical grinding of Mg with Ni and $Fe_2O_3$ is considered to facilitate nucleation and shorten the diffusion distances of the hydrogen atoms. After the hydriding-dehydriding cycling, the Mg-23.5Ni-$5Fe_2O_3$ sample contained $Mg_2Ni$ phase. Expansion and contraction of the hydride-forming materials (Mg and $Mg_2Ni$) with the hydriding and dehydriding reactions are also considered to increase the hydriding and dehydriding rates of the mixture by forming defects and cracks leading to the fragmentation of the particles. The temperature dependence of the hydriding rate of the sample is discussed.

Hydrogen Production from Steam Reforming of n-Hexadecane over Ni-Based Hydrotalcite-Like Catalyst (니켈계 유사 하이드로탈사이트 촉매상에서 n-헥사데칸의 수증기 개질에 의한 수소 생산)

  • Lee, Seung-Hwan;Moon, Dong-Ju
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.5
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    • pp.412-418
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    • 2010
  • Steam reforming of n-hexadecane, a major component of diesel over Ni-based hydrotalcite-like catalyst was carried out at $900^{\circ}C$ at atmospheric pressure with space velocity of $10,000h^{-1}$ and feed molar ratio of steam/carbon=3.0. Ni-based hydrotalcite catalyst was prepared by a solid phase crystallization (spc) method and characterized by $N_2$-physisorption, CO chemisorption, TPR., XRD, and TEM techniques. It was found that spc Ni/MgAl catalyst showed higher catalytic stability and inhibition of carbon formation than Ni/$\gamma-Al_2O_3$ catalyst under the tested conditions. The results suggest that the modified spc-Ni/MgAl catalyst after optimization may be applied for the SR reaction of diesel.