• Title/Summary/Keyword: Ni-$ZrO_2$

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Effect of Excess PbO Addition on Sintering and Piezoelectric Characteristics in Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 System (PbO 과잉량이 Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3계의 소결 및 압전특성에 미치는 영향)

  • 전구락;김정주;조상희;김도연
    • Journal of the Korean Ceramic Society
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    • v.26 no.4
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    • pp.568-574
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    • 1989
  • Effect of PbO addition on sintering and piezoelectric properties at 0.45Pb(Ni1/3Nb2/3)O3-0.40PbTiO3-0.15PbZrO3 composition which is tetragonal phase was investigated. In this composition, Porosity and dielectric constant were increased with excess PbO addition, but Kp and d31 was not changed. These variation of physical properties could be interpreted as composition change of solid grains from tetragonal to MPB region due to amount of PbO-rich liquid changing.

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Micro-Macro Domain Switching and Thermoelastic Martensitic Transformation in $PbZrO_3$-doped $Pb(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3$ System ($PbZrO_3$가 첨가된 $Pb(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3$ 계의 미소-거시 분역 반전과 열탄성 마르텐사이트 변태)

  • 윤만순;장현명
    • Journal of the Korean Ceramic Society
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    • v.32 no.9
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    • pp.967-976
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    • 1995
  • The possiblity of the existence of a spontaneous relaxor-normal ferroelectric transition was proposed and examined using 1~5 mol% PbZrO3-doped Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) systems having tetragonal symmetry at rom temperature. On cooling, the system with 60mol% Pb(Ni1/3Nb2/3)O3 underwent a spontaneous transition from a relaxor to a normal ferroelectric state. A microscopic examination demonstrates that the relaxornormal ferroelectric transition corresponds to a micro-macro domain switching accompanied with thermoelastic martensitic transformation. The long-range macrodomains below the transition temperature were characterized by twinlike 90$^{\circ}$macrodomains with tetragonal symmetry. The relaxor-normal ferroelectric transition was further correlated with the rhombohedral-tetragonal first-order structural transition.

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Synthesis of Ni supported on Ce-$ZrO_2$ for HDO Reaction to Produce New Generation Bio-diesel (차세대 바이오디젤 생산을 위한 HDO 반응용 Ce-$ZrO_2$에 담지된 Ni 촉매 합성)

  • Jeong, Dae-Woon;Eum, Ic-Hwan;Kim, Ki-Sun;Ko, Chang-Hyun;Roh, Hyun-Seog
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.527-527
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    • 2009
  • 1세대 바이오디젤인 fatty acid methyl ester(FAME)의 문제점을 극복하기 위하여 많은 연구가 진행 중 이다. 소위 차세대 바이오디젤은 triglyceride의 산소 화합물을 제거하여 정유 공정을 통해 생산된 디젤과 동일한 특성을 지닌 탄화수소로 전환시킨 오일이다. 이를 위하여 수소를 첨가하여 산소를 제거 시키는 Hydrodeoxygenation(HDO) 반응이 필요하다. 고온($300-400^{\circ}C$), 고압(50-100 bar)의 혹독한 조건에서 높은 수율과 안정성을 보이는 촉매 개발이 필요하다. 이를 위하여 반응물중의 산소를 효과적으로 제거하기 위하여 산소 전달능이 뛰어난 $CeO_2$ 담체에 열안정성을 높이는 $ZrO_2$를 조합한 $Ce-ZrO_2$ 담체를 선정하였으며 수소첨가 탈산소 반응에 활성을 나타낼 것으로 예상되는 니켈을 활성성분으로 선정하였다. 본 연구에서는 15%Ni-$Ce_{(1-x)}Zr_{(x)}O_2$ ($0{\leq}x{\leq}1$)촉매를 공침법(co-precipitation)으로 제조하였으며 $500^{\circ}C$에서 소성하였다. 촉매 특성분석은 XRD, BET, H2-TPR을 이용하였다.

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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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Dielectric and Piezoelectric Properties of Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 Solid Solution Ceramics (Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3계의 유전 및 압전특성)

  • 손정호;남효덕;조상희
    • Journal of the Korean Ceramic Society
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    • v.25 no.5
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    • pp.523-531
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    • 1988
  • The dielectric and piezoelectric properties with compositions in Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3-(PNN-PT-PZ)solid solution ceramics were investigated. In this study, the compsition ranges were 30 PNN 45mole%, 20 PT 50mole% and 50 PZ5mole%. As PT fraction were increased the grain size was increased and the fired density was decreased, but the changes of PNN fraction had no effect on the grain size. The Curie temperature was increased when PT and PNN fraction were increased. The displacement was increased but had a great hysteresis loss when PT fraction was increased. In morphotropic phase boundary, the maximum piezoelectric and electromechanical coupling factor were indicated. Morphotropic phase boundary(MPB) was 34 PT 36mole% in chang of compositions.

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$Ba(Zr_{0.85}Y_{0.15})O_{3-\delta}$-NI Composite Membrane for Hydrogen Separation by Aerosol Deposition Method (에어로졸 증착법(Aerosol Depostion method)에 의한 $Ba(Zr_{0.85}Y_{0.15})O_{3-\delta}$-NI 수소분리막 제조)

  • Park, Young-Soo;Choi, Jin-Sub;Byoun, Myoung-Sub;Kim, Jin-Ho;Hwang, Kwang-Taek
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.4
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    • pp.271-277
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    • 2010
  • $(Ba(Zr_{0.85}Y_{0.15})O_{3-\delta})$ oxide, showing high protonic conductivity at high temperatures and good chemical stability with $CO_2$ are referred to as hydrogen separation membrane. For high efficiency of hydrogen separation ($H_2$ flux and selectivity) and low fabrication cost, ultimate thin and dense BZY-Ni layer has to be coated on a porous substrate such as $ZrO_2$. Aerosol depostion (AD) process is a novel technique to grow ceramic film with high density and nano-crystal structure at room-temperature, and may be applicable to the fabrication process of AD integration ceramic layer effectively. XRD, SEM, X-ray mapping measurements were conducted in order to analyze the characteristics of BZY-Ni membrane fabricated by AD process. it is observed that it is homogeneous distribution for BZY-Ni. The result of $H_2$ permeation rate suggests that BZY-Ni composite is higher than BZY.

A Study on the joining of $Al_2O_3$ to STS 304 with using Cu-7.5wt% Zr Insert metal (Cu-7.5wt% Zr 삽입 금속을 이용한 $Al_2O_3$-STS 304 접합체 계면 조직에 관한 연구)

  • 김병무;한원진;강정윤;이상래
    • Journal of Welding and Joining
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    • v.11 no.1
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    • pp.62-72
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    • 1993
  • Recently there is an increased interest in joining of ceramics to metals and brazing now an accepted method of joining for a wide variety of ceramic to metal combination. The present research work is aimed at establishing the basis of the metal-ceramic joining of $Al_{2}$O$_{3}$ to STS 304 with using Cu-7.5wt% Zr insert metals. Also the microstructures of the brazed joints were observed by using optical microscope and SEM and the reaction products were analyzed by using EDX, WDX and XRD. As a result, the following findings were obtained. The reaction layers of the brazed joints of $Al_{2}$O$_{3}$ to STS 304 are composed of four layers at the bonded interlayer. Double reaction layers are formed at the interface of $Al_{2}$O$_{3}$ insert metal. Layer I was composed of ZrO$_{2}$ particles, Fe-Cr-Ni compounds in Cu matrix, while layer II ZrO$_{2}$ band phase containing Fe-Cr-Ni compounds.

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