• Title/Summary/Keyword: Ni/MgO

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Application of Ultrasonic Wet-Magnetic Separation Method to Prepare Nano-sized MgxNiyZn1-x-yFe2O4 (MgxNiyZn1-x-yFe2O4나노입자 제조를 위한 초음파 습식 자기분류법의 적용)

  • Gu, Mun-Seon;Choe, Yong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2016.11a
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    • pp.201.2-201.2
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    • 2016
  • $Mg_xNi_yZn_{1-x-y}Fe_2O_4$ ferrite powders were prepared by self-propagating high temperature synthesis followed by classified by ultrasonic wet-magnetic separation method to get nano-sized particles with high purity. The $Mg_xNi_yZn_{1-x-y}Fe_2O_4$ ferrites were well formed by using several powders like iron, nickel oxide, zinc oxide and magnesium oxide at 0.1 MPa of oxygen pressure. The ultrasonic wet-magnetic separation of pre-mechanical milled ferrite powders produced the powders with average size of $3.7-0.8{\mu}m$. The addition of a surfactant during the separation process improved productivity more than twice. The coercive force, maximum magnetization and residual magnetization of the $Mg_xNi_yZn_{1-x-y}Fe_2O_4$ nano-powders with 810 nm size were 45.89 Oe, 53.92 emu/gOe, 0.4 emu/Oe, respectively.

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RF (Radio-Frequency) Thermal Plasma Synthesis of Ni-Based Nano Powders

  • Seo, Jun-Ho;Nam, Jun-Seok;Lee, Mi-Yeon;Kim, Jeong-Su
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.138-138
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    • 2013
  • Ni-CeO2 및 Ni-MgO와 같이 Ni이 포함된 나노복합물질을 고주파 유도결합 플라즈마를 이용하여 합성하였다. 이를 위해, 먼저, 1~100 ${\mu}m$ 크기의 가상 Ni 입자와 고융점 세라믹 입자가 플라즈마 유동 내에서 겪는 열전달 과정을 수치해석을 통해 묘사하였다. 묘사 결과로부터, 완전 기화한 Ni 증기가, 채 기화하지 못하고 고체 형태로 남은 세라믹 입자 위에서 균일하게 응축된 형태를 갖는 Ni-세라믹 나노입자 합성을 예측하고, 실제 합성 실험을 25 kW 급 고주파 유도결합 플라즈마에 0.1~10 ${\mu}m$ 크기의 Ni, CeO2 및 MgO 분말을 주입하여 수행하였다. 마지막으로, 실험을 통해 합성된 Ni 계 복합나노물질에 대해, FE-SEM 및 TEM 사진 분석과 EDS 및 ICP-AES 성분 분석을 진행하고, 수치해석을 통해 예측된 결과와 비교 검토하였다.

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Electromagetic Wave Absorbing Properties of $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$(X=Cu, Mg, Mn)-Rubber Composite ($Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$(X=Cu, Mg, Mn)-Rubber Composite의 전파흡수특성에 관한 연구)

  • Im, Hui-Dae;Yun, Guk-Tae;Lee, Chan-Gyu
    • Korean Journal of Materials Research
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    • v.9 no.12
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    • pp.1234-1239
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    • 1999
  • Electromagnetic wave asorbing properties of the $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$, where X was replaced by substitution elements Cu, Mg, Mn, have been studied. The structure, shape, size and magnetic properties of the $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$ were analyzed by XRD, SEM, VSM. The relative complex permittivity, permeability, and electromagnetic wave absorbing properties were measured by Network Analyzer. The structure, shape, size and magnetization value of the $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$ were found to be similar in spite of substitution elements. The coercive force and hysteresis-loss showed maximum value when Mg was substituted for X. The dielectric loss(${\varepsilon}_r"/{\varepsilon}_r'$) was found to be maximum value when Mn was substituted for X. Also the magnetic loss(${\mu}_r"/{\mu}_r'$} was found to be maximum with Cu substitution. The electromagnetica wave absorbing property of the $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$-Rubber composite with 4mm thickness was excellent as over - 40dB at 9GHz, and the $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$-Rubber composite with 8mm thickness was over-40dB at 2GHz. Those composites also showed superior microwave absorbing properties.

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Geochemical Dispersion and Enrichment of Fluvial Sediments Depending on the Particla Size Distribution (입도분포에 따른 하상퇴적물의 지구화학적 분산 및 부화)

  • 이현구
    • Economic and Environmental Geology
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    • v.32 no.3
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    • pp.247-260
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    • 1999
  • Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

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Hydrogen Storage Characteristics of Melt Spun Mg-23.5Ni-xCu Alloys and Mg-23.5Ni-2.5Cu Alloy Mixed with $Nb_{2}O_{5}$ and $NbF_{5}$

  • Hong, Seong-Hyeon;Kwon, Sung-Nam;Song, Myoung Youp
    • Korean Journal of Metals and Materials
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    • v.49 no.4
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    • pp.298-303
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    • 2011
  • Mg-23.5 wt%Ni-xwt%Cu (x = 2.5, 5 and 7.5) samples for hydrogen storage were prepared by melt spinning and crystallization heat treatment from a Mg-23.5 wt%Ni-5 wt%Cu alloy synthesized by the gravity casting method. They were then ground under $H_2$ to obtain a fine powder. Among these samples the Mg-23.5Ni-2.5Cu sample had the highest hydriding and dehydriding rates after activation. The Mg-23.5Ni-2.5Cu sample absorbed 3.59 and 4.01 wt%H for 10 and 60 min, respectively, at 573K under 12 bar $H_{2}$. The activated 88(87.5Mg-10Ni-2.5Cu)-$5Nb_{2}O_{5}-7NbF_{5}$ sample absorbed 2.93 wt%H for 10 min, and 3.14 wt%H for 60 min at 573K under 12 bar $H_{2}$.

The Performance of NI/$MgAl_2O_4$ Coated Metal Monolith in Natural Gas Steam Reforming for Hydrogen Production (NI/$MgAl_2O_4$코팅된 금속 모노리스 촉매의 수소 생산을 위한 천연가스 수증기 개질 반응특성에 관한 연구)

  • Choi, Eun-Jeong;Koo, Kee-Young;Jung, Un-Ho;Rhee, Young-Woo;Yoon, Wang-Lai
    • Journal of Hydrogen and New Energy
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    • v.21 no.6
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    • pp.500-506
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    • 2010
  • The metal monolith catalyst coated with 15wt% Ni/$MgAl_2O_4$ is applied to the natural gas steam reforming for hydrogen production. To address the improvement of adherence between metal monolith and catalyst coating layer, the pre-calcination temperature as well as the coating conditions of $Al_2O_3$ sol are optimized. When the Fe-Cr alloy monolith is pre-calcined at $900^{\circ}C$ for 6 h, $Al_2O_3$ layer was formed uniformly on the entire surface of the metal substrate. It is seen that the formation of $Al_2O_3$ layer on the monolith surface is essential for the uniform coating of $Al_2O_3$ sol onto the monolith substrate. The monolith catalyst coated with 10wt% $Al_2O_3$ sol shows high $CH_4$ conversion and good thermal stability as compared with the monolith catalyst without $Al_2O_3$ sol coating under severe reaction conditions with high GHSV of 30,000 $h^{-1}$ at $700^{\circ}C$. In addition, the metal monolith catalyst shows higher catalytic activity and better thermal conductivity than 15wt% Ni/$MgAl_2O_4$ pellet catalyst.

Microstructure and Electrical Properties of Zn-Pr-Co-Y-M(M=Ni, Mg, Cr) Oxide-Based Varistors (Zn-Pr-Co-Y-M(M=Ni, Mg, Cr) 산화물계 바리스터의 미세구조 및 전기적 특성)

  • Nahm Choon-Woo;Park Jong-Ah
    • Korean Journal of Materials Research
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    • v.14 no.6
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    • pp.420-424
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    • 2004
  • The microstructure and electrical properties of $ZnO-Pr_{6}$$O_{11}$ $-CoO-Y_2$$O_3$-based varistors were investigated with and without various metal oxide additives (NiO, MgO, and $Cr_2$$O_3$). The addition of NiO promoted the grain growth while that of Cr$_2$O$_3$ decreased average grain size. Thereby, the varistor voltage was higher in $Cr_2$$O_3$-added composition. Among $ZnO-Pr_{6}$ $O_{11}$ /$-CoO-Y_2$$O_3$-based varistors, the$ Cr_2$$O_3$-added varistor exhibited the highest nonlinear exponent (51.2), the lowest leakage current (1.3 $\mu$A), and the lowest dielectric dissipation factor (0.0433).

Preparation of 27Ni6Zr4O143M(M=Mg, Ca, Sr, or Ba)O/70 Zeolite Y Catalysts and Hydrogen-rich Gas Production by Ethanol Steam Reforming

  • Kim, Dongjin;Lee, Jun Su;Lee, Gayoung;Choi, Byung-Hyun;Ji, Mi-Jung;Park, Sun-Min;Kang, Misook
    • Bulletin of the Korean Chemical Society
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    • v.34 no.7
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    • pp.2073-2080
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    • 2013
  • In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the $Ni_6Zr_4O_{14}$ main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, $H_2$-TPR, $NH_3$-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and $H_2$ production and ethanol conversion were maximized to 82% and 98% respectively in 27($Ni_6Zr_4O_{14}$)3MgO/70Zeolite Y catalyst at $600^{\circ}C$. Many carbon deposits and carbon nano fibers were seen on the surface of $30Ni_6Zr_4O_{14}$/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

Mineralogy of Garnierite from New Caledonian Ni Lateritic Ore (뉴칼레도니아 니켈 라테라이트 광석 내 가니어라이트의 광물학적 특징)

  • Cho, Hyen-Goo;Kim, Soon-Oh;Kim, Sang-Bae
    • Journal of the Mineralogical Society of Korea
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    • v.24 no.4
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    • pp.253-263
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    • 2011
  • Mineralogical characteristics of garnierite ores from the Nakety, Kouaoua, and Ouaco Ni laterite deposits in New Caledonia are investigated using optical microscopy, powder X-ray diffractometer, and electron proble microanalyzer. Green garnierite ores have colloform, cellular, and boxwork texture, which are formed by precipitation under low temperature surface environment. They are mainly composed of Ni-bearing talc~willemseite series mineral and partly of lizardite. In Ni-bearing talc~willemseite series mineral, NiO contents are Ouaco (average 40.63%), Nakety (average 28.58%), and Kouaoua (average 24.90%), in descending order. Ni atomic percentage replacing Mg in octahedral site are 43.5~85.0%. Dark brown garnierite ores show cellular or boxwork texture, and consist of lizardite~Ni lizardite with some Ni-bearing talc~willemseite series mineral. Ni contents in lizardite~Ni lizardite are 1.14~4.06 wt. % and Ni atomic percentage replacing Mg in octahedral site 1.7~6.8%. Low NiO content in dark brown garnierite attributes to high Fe content replacing Mg in octahedral site.