• 한국세라믹학회지
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• 제50권6호
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• pp.423-428
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• 2013

Porous YSZ ceramics are fabricated using 3 mol% yittria-stabilized zirconia (3YSZ) and NiO with different particlesizes (0.6 and 7 ${\mu}m$). Nickel oxide (NiO) is added to the YSZ powder as a pore former with different amounts(40, 50, and 60 vol%) and at different sintering temperatures (1350 and $1400^{\circ}C$) are applied in order to evaluate the temperature effects on the pore and mechanical properties. Heat treatment is conducted after sintering at $700^{\circ}C$ in $H_2$ for the NiO reduction process; then, Ni is removed using a $HNO_3$ etchant solution. According to the NiO contentand sintering temperatures, 41-67% porous YSZ ceramic is obtained and the flexural strength increases, while the porosity decreases with an increasing sintering temperature. The optimum flexural strength ($136.5{\pm}13.4MPa$) and porosity (47%) for oxygen transport porous YSZ membrane can be obtained with 40 vol% of 7 ${\mu}m$ NiO particle at a sintering temperature of $1350^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.783-784
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• 2011

• Nuclear Engineering and Technology
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• 제32권5호
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• pp.514-520
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• 2000

The mechanism of corrosion behavior has to be understood clearly to select an optimum material for handling molten salts to be used in the oxide reduction process of PWR spent fuel. In this study, the oxidation states of corrosion products on the surface of Inconel 600 and 800H as well as their chemical compositions and structural informations were determined by using XPS, ICP-AES, AAS, EPMA and XRD after the corrosion experiment with lithium molten salts at 75$0^{\circ}C$ for 25 hours. Nickel and oxygen were detected from the corrosion products on the surface of Inconel plates and chromium was found to be dissolved out into lithium molten salts leaving cracks on the surface. The corrosion products were identified as metal oxides such as Fe$_2$O$_3$, Cr$_2$O$_3$, NiO, NiFe$_2$O$_4$and MnO by using XPS and XRD.

• 한국세라믹학회지
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• 제50권1호
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• pp.63-69
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• 2013

Negative-temperature coefficient (NTC) thermistors based on nickel manganite spinel ($NiMn_2O_4$) are widely used for many applications, such as sensors and temperature compensators, due to their good thermistor characteristics and stabilities. However, to achieve thermistors with a high NTC B constant, which is an important figure of merit pertaining to the degree of temperature sensitivity, the activation energy should be high such that high resistivity at ambient temperatures results. To obtain a high B constant and low resistivity, Al and Si modified spinel structured $Ni_{0.6}Si_{0.2}Al_{0.6}Mn_{1.6}O_4$ hybrid thick films with the conducting metal oxide of $LaNiO_3$ were fabricated on a glass substrate by aerosol deposition at room temperature (RT). The NTC-$LaNiO_3$ hybrid thick films showed resistivity as low as < $100k{\Omega}\;cm$ at $90^{\circ}C$, which is one or two orders of magnitude lower than that of the monolithic NTC films, while retaining a high B constant of $NiMn_2O_4$ of over 5500 K when 20 wt% $LaNiO_3$ was added without a post-thermal treatment. These phenomena are explained by the percolation threshold mechanism.

• 한국수소및신에너지학회논문집
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• 제24권3호
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• pp.237-241
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• 2013

The correlation between NiO-YSZ microstructure and its electrical property used for SOFC anode was critically evaluated with image processing and direct measurement techniques. These innovative processing techniques were employed to quantify the contiguity of the anode constituent phase. The calculated contiguities were then correlated with electrical conductivity attained from 4-probe DC method. This investigation described that contiguity of nickel oxide phases of an anode has a linear relationship with its electrical conductivity. We observed that the contiguity of NiO increased from 0.18 to 0.50 then electrical conductivity attained was significantly increased from 520 S/cm to 1468 S/cm at $900^{\circ}C$.

• 한국표면공학회지
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• 제51권4호
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• pp.231-236
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• 2018

We report p-type electrical characteristics of the amorphous $La_2NiO_{4+{\delta}}$ thin films which were sputtered on the glass substrates using an RF sputtering system. As-deposited thin films at room temperature and $300^{\circ}C$ were amorphous in nature. Post-annealing of the thin film samples over $400^{\circ}C$ resulted in the nano-crystallization of the $La_2NiO_{4+{\delta}}$. The electrical properties of the films were much dependent on the oxygen partial pressure, temperature of the post-annealing and sputtering ambient. The as-deposited samples at room temperature show a hole concentration of $7.82{\times}10^{13}cm^{-3}$, and it could be increased as high as $3.51{\times}10^{22}cm^{-3}$ when the films were post-annealed in an oxygen atmosphere at $500^{\circ}C$. Such p-type conductivity behavior of the $La_2NiO_{4+{\delta}}$ films suggests that the amorphous and nano-crystallized $La_2NiO_{4+{\delta}}$ films have potential for the application as p-type semiconductive or conductive materials at low temperatures where material diffusion is limited.

• Advances in nano research
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• 제2권2호
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• pp.77-88
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• 2014

Solvothermal treatment of late transition metal acetylacetonates in a novel medium composed either of pure acetophenone or acetophenone mixtures with amino alcohols offers a general approach to uniform hydrophilic metal nanoparticles with high crystallinity and low degree of aggregation. Both pure metal and mixed-metal particles can be accesses by this approach. The produced materials have been characterized by SEM-EDS, TEM, FTIR in the solid state and by Nanoparticle Tracking Analysis in solutions. The chemical mechanisms of the reactions producing nanoparticles has been followed by NMR. Carrying out the process in pure acetophenone produces palladium metal, copper metal with minor impurity of $Cu_2O$, and NiO. The synthesis starting from the mixtures of Pd and Ni acetylacetonates with up to 20 mol% of Pd, renders in minor yield the palladium-based metal alloy along with nickel oxide as the major phase. Even the synthesis starting from a mixed solution of $Cu(acac)_2$ and $Ni(acac)_2$ produces oxides as major products. The situation is improved when aminoalcohols such as 2-aminoethanol or 2-dimethylamino propanol are added to the synthesis medium. The particles in this case contain metallic elements and pairs of individual metals (not metal alloys) when produced from mixed precursor solutions in this case.

• 자원리싸이클링
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• 제16권6호
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• pp.3-9
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• 2007

생활 폐기물은 대부분 유리류와 자기류뿐만 아니라 많은 양의 iron을 함유하고 있으며 약 $3{\sim}11%$에 달한다. 대부분의 iron은 Ni-Fe와 Ni-Cr-Fe 같은 합금으로 존재하거나, 부식방지와 광택을 위해 Ni와 Cr로 도금된 iron으로 존재하고 있기 때문에 소각로에서 소각될 경우 철 재품 표면에 심하게 파손된 $Fe_3O_4$층과 함께 $NiFe_2O_4$와 FeCr_2O_4$을 형성하게 되어 바닥재에 존재하게 되어 중금속산화물 층을 형성시킬 수 있다. iron은 자력이 매우 강해 자력선별에 의해 쉽게 선별되며 이러한 효과로 인해 중금속 산화물의 선별까지 얻을 수 있다. 또한 바닥재는 다양한 Ni와 Cr 산화물들을 함유하고 있으며, Ni와 Cr은 강자성을 띈 물질이기 때문에 자력선별에 의해 큰 영향을 받을 수 있다. 따라서 자력선별에 따른 Ni와 Cr의 거동에 대해 조사하였으며 그 밖의 다른 중금속(Cu, Pb, Cd, As)들의 거동 또한 확인해 보았다. 그 결과 Ni와 Cr은 약 $45{\sim}50%$의 선별율을 보였으며, Cu와 Pb는 $15{\sim}20%$을 나타냈다. 또한 자력선별 전과 후의 바닥재에 대해 Ni와 Cr의 용출량을 확인해본 결과 자력선별 후 바닥재의 용출량이 더 낮음을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.156-168
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• 2023

This study investigates the high temperature oxidation behaviour of a Ni-20Cr-1.2Si (wt.%) alloy in steam from 1200 ℃ to 1350 ℃ by Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). The results demonstrate that exposed Ni-based alloy developed a thin oxide scale, consisted mainly of Cr₂O₃. The oxidation kinetics obtained from the experimental results was applied to evaluate the hydrogen generation considering a simplified reactor core model with different cladding alloys following an unmitigated Loss-Of-Coolant Accident (LOCA) scenario in a hypothetical Small Modular Reactor (SMR). Overall, experimental data and simulations results show that both Fe-based and Ni-based alloys may enhance cladding survivability, delaying its melting, as well as reducing hydrogen generation under accident conditions compared to Zr-based alloys. However, a substantial neutron absorption occurs when Ni-based alloys are used as cladding for current uranium-dioxide fuel systems, even when compared to Fe-based alloys.

• 전기화학회지
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• 제6권3호
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• pp.178-182
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• 2003

용융탄산염형 연료전지의 특성을 결정짓는 탄산염 전해질에 있어, 기존의 Li-K와 Li-Na 탄산염과는 다른 Li-Na-K 삼원계 탄산염의 특성을 산소환원 및 산화니켈 용해거동을 통해 검토하였다. 대상 삼원계 전해질은 Li-Na-K=47.4-32.6-20, 60-20-20, 50-40-10, $40-40-20mo1\%$이었으며, $650^{\circ}C$, 1기압 조건에서 산소환원 거동은 전기화학적 방법을 통해, NiO용해거동은 화학적 방법을 통해 검토하였다 삼원계 조성에 따라 산소환원 전류치의 차이가 관찰되어, 산소용해도가 조성에 의존함을 나타내었다. 또한 $Li-Na-K = 50-40-10 mol\%$ 조성에서는 다른 형태의 산소환원 피크가 관찰되어 조성에 따라 산소환원 메카니즘의 차이가 존재할 수 있음을 시사하였다. 그러나 산화니켈 용해도는 조성에 크게 의존하지 않는 특성을 보여주었다.