• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.285-291
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• 2004

LiCl-$Li_2O-O_2$ 용융염계에서 용융염 취급장치의 구조재료를 위한 평가의 일환으로 Inconel 718, X-750, Haynes 75, 263 합금의 부식거동을 분위기온도; $650^{\circ}C$, 부식시간: 24~168h, $Li_2O$농도; 3wt%, 혼합가스농도; Ar-10%$O_2$에서 조사하였다. LiCl-$Li_2O-O_2$ 용융염계에서 부식속도는 Haynes 263 ＜ Haynes 75 ＜ Inconel X-750 ＜ Inconel 718 순서로 나타났으며, Haynes 263 합금이 가장 우수한 내부식성을 나타내었다. Haynes 75의 부식생성물은 $Cr_2O_4$, $NiFe_2O_4$, $LiNiO_2$, $Li_2NiFe_2O_4$, Inconel 718의 부식생성물은 $Cr_2O_4$ 및 $NiFe_2O_4$ 이며 Haynes 263은 $Li(Ni,Co)O_2$, $NiCr_2O_4$ 및 $LiTiO_2$, Inconel X-750은 $Cr_2O_3$, $NiFe_2O_4$,$FeNi_3$, (Al,Nb,Ti)$O_2$의 부식생성물을 나타내었다. Haynes 263은 국부부식의 거동을 보이는 반면, Haynes 75, Inconel 718 및 Inconel X-750은 전면 부식 거동을 나타내었다.

• 한국산학기술학회논문지
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• 제19권1호
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• pp.699-704
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• 2018

일차원 나노구조물은 양자 갇힘 효과 및 나노와이어가 갖는 체적 대비 높은 표면적 비에 기인하는 독특한 전기적, 광학적, 광전기적, 전기화학적 특성으로 인하여 많은 주목을 받아왔다. 특히 수직으로 성장된 나노와이어는 체적 대비 높은 표면적 비의 특성을 나타낸다. VLS(Vapor-Liquid-Soild) 공정은 나노구조물의 성장 과정에서 자기정렬 효과 때문에 더욱 주목을 받는다. 본 연구에서는 두 영역 열화학 기상증착법을 이용하여 Si\$SiO_2$(300 nm)\Pt 기판 위에 수직으로 정렬된 실리콘 옥사이드 나노기둥을 VLS 공정으로 성장시켰다. 성장된 실리콘 옥사이드 나노기둥의 형상과 결정학적 특성을 주사전자현미경 및 투과전자현미경으로 분석하였다. 그 결과 성장된 실리콘 옥사이드 나노기둥의 지름과 길이는 촉매 박막의 두께에 따라 변하였다. 실리콘 옥사이드 나노 기둥의 몸체는 비정질 상을 나타내었으며, Si과 O로 구성되어 있었다. 또한 성장된 실리콘 옥사이드 나노 기둥의 머리는 결정성을 나타내었으며, Si, O, Pt 및 Ti으로 구성되어 있었다. 실리콘 옥사이드 나노 기둥의 수직 정렬은 촉매물질인 Pt/Ti 합금의 결정성 정렬 선호에 기인하는 것으로 판단되며, 수직 성장된 실리콘 옥사이드 나노기둥은 기능성 나노소재로 활용이 가능할 것으로 기대된다.

• 한국분말재료학회지
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• 제9권6호
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• pp.394-408
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• 2002

Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. $Mg_{55}Y_{15}Cu_{30}$- based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% $Y_2O_3$ particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The $Y_2O_3$ additions increase the mechanical strength of the composites compared to the $Mg_{55}Y_{15}Cu_{30}$ metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. $Al_{98-x}Mn_xCe_2$ (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of $Al_{63}Cu_{25}Fe_{12}$ leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming $Al_{100-x}$$(Al_{0.63}Cu_{0.25}Fe_{0.12})_x$ (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of ${\sigma}_y{\geq}$700 MPa and a ductility of ${\varepsilon}_{pl}{\geq}$5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is ${\sigma}_y{\leq}$550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few $Ti_3Sn,\;{\beta}$-(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.

• 한국결정성장학회지
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• 제22권5호
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• pp.227-232
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• 2012

차세대 원자력발전용 고온 열교환기 소재로 이용될 가능성이 높은 Ni-Cr계 고온합금인 Inconel 617과 Hastelloy X의 표면처리에 따른 FLiNaK(LiF-NaF-KF) 용융염 하에서의 고온물성에 대한 연구를 수행하였다. Inconel 617과 Hastelloy X기판 상에 각각 PVD인 arc discharge 및 sputtering법에 의해 TiAlN 및 $Al_2O_3$ 박막을 코팅 하였다. 이러한 표면처리가 이들 합금의 FLiNaK 용융염 하 고온 안정성에 미치는 영향에 대해 연구하였다. 용융염 하 Ni-Cr계 고온합금의 부식 원리를 이해하기 위해, 용융염 수송 loop에 사용 중 파단된 Inconel 파이프에 대한 미세구조 분석을 수행하였다. 표면처리 된 합금들을 $600^{\circ}C$ 용융염 내에서 열처리 하였으며, 열처리 전후 시편들에 대해 상형성, 미세구조 등 고온 물성 변화를 측정하였다. 연구결과 코팅되지 않은 경우 보다 TiAlN 및 $Al_2O_3$ 박막이 코팅된 소재에서 보다 우수한 고온 안정성을 보여주었다.

• 대한치과보철학회지
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• 제45권5호
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• pp.601-610
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• 2007

Statement of problem: The adhesion between titanium and ceramic is less optimal than conventional metal-ceramic bonding, due to reaction layer form on cast titanium surface during porcelain firing. Purpose: This study characterized the effect of titanium-ceramic adhesion after gold and TiN coating on cast and wrought titanium substrates. Material and method: Six groups of ASTM grade II commercially pure titanium and cast titanium specimens$(13mm{\times}13mm{\times}1mm)$ were prepared(n=8). The conventional Au-Pd-In alloy served as the control. All specimens were sandblasted with $110{\mu}m\;Al_2O_3$ particles and ultrasonically cleaned for 5min in deionized water and dried in air before porcelain firing. An ultra-low-fusing dental porcelain (Vita Titankeramik) was fused on titanium surfaces. Porcelain was debonded by a biaxial flexure test at a cross head speed of 0.25mm/min. The excellent titanium-ceramic adherence was exhibited by the presence of a dentin porcelain layer on the specimen surface after the biaxial flexure test. Area fraction of adherent porcelain (AFAP) was determined by SEM/EDS. Numerical results were statistically analyzed by one-way ANOVA and Student-Newman-Keuls test at ${\alpha}=0.05$. Results: The AFAP value of cast titanium was greatest in the group 2 with TiN coating, followed by group 1 with Au coating and the group 3 with $Al_2O_3$ sandblasting. Significant statistical difference was found between the group 1, 2 and the group 3 (p<.05). The AFAP value of wrought titanium was greatest in the group 5 with TiN coating, followed by the group 4 with Au coating and the group 6 with $Al_2O_3$ sandblasting. Conclusion: No significant difference was observed among the three groups (p>.05). The AFAP values of the cast titanium and the wrought titanium were similar. However the group treated with $Al_2O_3$ sandblasting showed significantly lower value (p<.05).

• 자원리싸이클링
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• 제26권6호
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• pp.3-9
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• 2017

본 연구에서는 anode로 Kroll 공정 처리된 Ti 스폰지를 사용하여 아크 전류, 아크 전압, 플라즈마 가스 종류에 따른 플라즈마 아크 재용해 거동을 조사하였다. 진공펌프의 토출 압력 범위($200{\sim}300kgf/cm^2$)에서는 토출 압력 증가에 따라 주어진 아크 길이에서 아크 전압이 크게 달라지지 않았다. 이것은 작업하는 동안 진공챔버내 압력이 거의 변화하지 않고, 주어진 분위기 압력을 잘 유지함을 의미한다. 여러가지 아크 전류 조건(700~900A)에서, 아크 전류 증가에 따라 아크 전압이 약간 증가하였고, anode 재료변화에 대한 효과도 이전 연구결과와 비교하였다. 분위기 가스가 Ar에서 He으로 변경되는 경우에는 정상상태의 출력이 2배 정도 향상되는 효과가 관찰되었다. 플라즈마 아크 장치의 출력 증가는 Ti 스폰지의 재용해 속도 증가와 함께 잉곳 표면도 양호해졌다. New 스크랩인 타이타늄과 old 스크랩인 지르코늄 합금을 플라즈마 아크 재용해한 결과, 매우 양호한 표면을 갖는 잉곳을 제조할 수 있었다.

• Korean Chemical Engineering Research
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• 제57권1호
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• pp.11-16
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• 2019

높은 산소 분리 특성과 $CO_2$에 대한 안정성을 보인 $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$(LSTF)가 코팅된 $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$(BSCF) 분리막을 bench 규모의 장치에 적용하여 산소 투과 실험을 수행 하였다. 또한 실험실 규모 장치와 bench 규모장치의 분리막 반응기 내 온도 구배에 따라서 분리막을 3영역으로 나누어 각각 비교 분석하였다. $900^{\circ}C$까지 온도 범위에서 산소 투과 실험을 진행하면서 Cr 침적의 온도 의존성을 조사하였다. 그 결과 실험실 장치에서 측정한 산소 투과율인 $3.79ml/min{\cdot}cm^2$에 비해 현저히 낮은 $2.37ml/min{\cdot}cm^2$를 확인했다. 이와 같은 산소 투과율의 감소는 XRD와 SEM/EDS 분석을 통하여 분리막 반응기의 합금 재질에서 방출되어 나온 기상 Cr의 분리막 표면 침적에 의한 것임을 밝혀냈다. 특히 중온 영역에서 많은 양의 Cr이 발견되었다.

• 한국수소및신에너지학회논문집
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• 제16권3호
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• pp.244-252
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• 2005

It is very interesting and important in the academic point of view and in practical use the hydrogen-induced phase separation(HIPS) which appears during hydrogen heat treatment. Since hydrogen can be removed very fast by pumping it out the hydrogen-induced new lattice phase which can not be obtained without hydrogen can be preserved as meta-stable state. In this study it has been investigated whether the HIPS appear in Pd-Al, Pd-Co, Pd-Cr, Pd-Ti, Pd-V and Pd-Zr alloys and discussed thermodynamic representation of the HIPS. The Pd alloys were arc-melted under argon atmosphere and remelted 4 or 5 times for homogenization. The alloys were annealed at 600$^{\circ}C$ under vacuum for 24 hrs and then subjected to pressure-composition isotherm measurements at 100$^{\circ}C$. The hydrogen heat treatment(HHT) of samples was carried out at 600$^{\circ}C$ under hydrogen pressure of 70 bar for 6 days and PC isotherms at 100$^{\circ}C$ were measured. By comparing the PC isotherms measured before and after HHT, occurrence of phase separation was determined. The experimental results showed that the HIPS appeared only in Pd-0.05Co alloy. For Pd-Co alloys with various composition the PC isotherms were measured. By adopting Park-Flanagan model for ternary thermodynamics the Gibbs free energy change for Pd-Co-H solid solution was calculated and subsequently with this the HIPS in Pd-Co alloy was explained fairly.

• 한국전기전자재료학회논문지
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• 제31권3호
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• pp.141-145
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• 2018

Ni-InGaAs shows promise as a self-aligned S/D (source/drain) alloy for n-InGaAs MOSFETs (metal-oxide-semiconductor field-effect transistors). However, limited thermal stability and instability of the microstructural morphology of Ni-InGaAs could limit the device performance. The in situ deposition of a Pd interlayer beneath the Ni layer was proposed as a strategy to improve the thermal stability of Ni-InGaAs. The Ni-InGaAs alloy layer prepared with the Pd interlayer showed better surface roughness and thermal stability after furnace annealing at $570^{\circ}C$ for 30 min, while the Ni-InGaAs without the Pd interlayer showed degradation above $500^{\circ}C$. The Pd/Ni/TiN structure offers a promising route to thermally immune Ni-InGaAs with applications in future n-InGaAs MOSFET technologies.

• Progress in Superconductivity
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• 제9권1호
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• pp.85-90
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• 2007

Lanthanum aluminate($LaAlO_3$) film has been prepared on single crystal and metal substrates by dip coating method. Lanthanum acetate and aluminum were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate in acetate glacial acetic acid solution after being refluxed. Coating solution was obtained by diluting the gel with methanol and 2-methoxyethanol to adjust the total cation concentration to 0.67 M. Precursor coated film was prepared by dip-coating with a speed of 25 mm/min on various substrates such as $LaAlO_3$ (001), MgO(001), $SrTiO_3$(001) single crystal, LMO/MgO/Ni-alloy. Thin films have been obtained by heat treating the precursor film at various temperatures from $600^{\circ}C{\sim}900^{\circ}C$ and various heating rate from $0.83^{\circ}C/min{\sim}1.25^{\circ}C/min$ under $Ar/O_2$ mixture containing 1000ppm oxygen. The films have been characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). XRD analysis for the prepared film showed that $LaAlO_3$ thin films with a preferred orientation of (100) plane parallel to substrate surface were obtained at $800^{\circ}C(1.11\;^{\circ}C/min)$ on LMO/MgO/Ni-alloy substrate, but the intensity decreased with the increase of heat treatment temperature.