• 제목/요약/키워드: Nanophase

검색결과 27건 처리시간 0.031초

한국형 인공월면토 생산 시스템 효율성 및 Fe(0) 모사를 위한 수소 환원반응에 관한 실험적 평가 (Experimental Assessment of Manufacturing System Efficiency and Hydrogen Reduction Reaction for Fe(0) Simulation for KLS-1)

  • 진현우;김영재;류병현;이장근
    • 한국지반공학회논문집
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    • 제36권8호
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    • pp.17-25
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    • 2020
  • 최근 한국건설기술연구원은 우주개발 및 심우주 탐사를 위한 전진기지로서 활용도가 높은 달에 관한 연구수행을 목적으로 달 행성 지상 환경 모사를 위한 대규모 지반 열 진공 챔버(DTVC)를 건설하였다. 유관연구 수행을 위해 대량의 한국형 인공월면토(KLS-1)가 요구되고 있음에도 불구하고 현실적으로 대량생산은 어려운 실정이다. 본 논문에서는 KLS-1의 대량 생산이 가능한 반자동화 시스템에 관해 상세하게 설명하고 있으며, 이것이 기존 생산 시스템보다 7배 이상 효율적임을 밝혀냈다. 뿐만 아니라, 월면토와의 유사성 증대를 위해 월면토 고유 특성인 nanophase Fe(0) (이하 np-Fe(0))을 모사하기 위한 실험적 연구를 진행하였다. 월면토를 이루는 광물 중 하나인 티탄철석(ilmenite)을 활용해 수소기체 환원반응을 진행한 결과, 700℃ 이상의 온도에서는 np-Fe(0)이 형성됨을 밝혀냈으며 900℃까지는 온도와 비례하여 np-Fe(0)이 증가함을 밝혀냈다.

Preparation and Physical Characterizations of Superparamagnetic Maghemite Nanoparticles

  • Yoon, Sunghyun
    • Journal of Magnetics
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    • 제19권4호
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    • pp.323-326
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    • 2014
  • Superparamagnetic maghemite nanoparticles were prepared by chemical co-precipitation, followed by a temperate oxidation stage, and investigated using FE-SEM, XRD, TGA, VSM, and M$\ddot{o}$ssbauer spectroscopy. Through SEM image and XRD analysis, its average particle size was found to be 13.9 nm. While VSM magnetic measurement showed typical superparamagnetic behavior at room temperature, M$\ddot{o}$ssbauer spectroscopic investigation revealed that non-vanishing magnetic hyperfine structure were retained. Cation distribution estimated from M$\ddot{o}$ssbauer spectroscopy confirmed the formation of maghemite nanophase in the sample.

High-Frequency Induction-Heated Combustion Synthesis and Consolidation of Nanostructured NbSi2 from Mechanically Activated Powders

  • Kim, Byung-Ryang;Yoon, Jin-Kook;Nam, Kee-Seok;Shon, In-Jin
    • 한국분말재료학회지
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    • 제15권4호
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    • pp.279-284
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    • 2008
  • Dense nanostructured $NbSi_2$ was synthesized by high-frequency induction-heated combustion synthesis (HFIHCS) method within 1 minute in one step from mechanically activated Nb and Si powders. Highly dense $NbSi_2$ with relative density of up to 99% was simultaneously synthesized and consolidated under the combined effects of an induced current and mechanical pressure of 60 MPa. The average grain size and mechanical properties (hardness and fracture toughness) of the compound were investigated.

소형 직접 메탄올 연료전지를 위한 나노 합금 전극 (Nanostructured Alloy Electrode for use in Small-Sized Direct Methanol Fuel Cells)

  • 박경원;최종호;박인수;남우현;성영은
    • 한국전기화학회:학술대회논문집
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    • 한국전기화학회 2003년도 연료전지심포지움 2003논문집
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    • pp.83-88
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    • 2003
  • PtRu alloy and $PtRu-WO_3$ nanocomposite thin-film electrodes for methanol electrooxidation were fabricated by means of a sputtering method. The structural and electrochemical properties of well-defined PtRu alloy thin-film electrodes were characterized using X-ray diffraction, Rutherford backscattering spectroscopy. X-ray photoelectron spectroscopy, and electrochemical measurements. The alloy thin-film electrodes were classified as follows: Pt-based and Ru-based alloy structure. Based on structural and electrochemical understanding of the PtRu alloy thin-film electrodes, the well-controlled physical and (electro)chemical properties of $PtRu-WO_3$, showed superior specific current to that of a nanosized PtRu alloy catalyst, The homogeneous dispersion of alloy catalyst and well-formed nanophase structure would lead to an excellent catalytic electrode reaction for high-performance fuel cells. In addition, the enhanced catalytic activity in nanocomposite electrode was found to be closely related to proton transfer in tungsten oxide using in-situ electrochemical transmittance measurement.

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Phase Identification of Nano-Phase Materials using Convergent Beam Electron Diffraction (CBED) Technique

  • Kim, Gyeung-Ho;Ahn, Jae-Pyoung
    • Applied Microscopy
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    • 제36권spc1호
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    • pp.47-56
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    • 2006
  • Improvements are made to existing primitive cell volume measurement method to provide a real-time analysis capability for the phase analysis of nanocrystalline materials. Simplification is introduced in the primitive cell volume calculation leading to fast and reliable method for nano-phase identification and is applied to the phase analysis of Mo-Si-N nanocoating layer. In addition, comparison is made between real-time and film measurements for their accuracy of calculated primitive cell volume values and factors governing the accuracy of the method are determined. About 5% accuracy in primitive cell determination is obtained from camera length calibration and this technique is used to investigate the cell volume variation in WC-TiC core-shell microstructure. In addition to chemical compositional variation in core-shell type structure, primitive cell volume variation reveals additional information on lattice coherency strain across the interface.