• 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.

• Journal of Powder Materials
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• v.12 no.6 s.53
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• pp.406-412
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• 2005

This work is to present a new synthesis of metallic glass (MG)/metallic glass (MG) composites using gas atomization and spark plasma sintering (SPS) processes. The MG powders of $Cu_{54}Ni_6Zr_{22}Ti_{18}$ (CuA) and $Ni_{59}Zr_{15}Ti_{13}Nb_7Si_3Sn_2Al_1$(NiA) as atomized consist of fully amorphous phases and present a different thermal behavior; $T_g$ (glass transition temperature) and $T_x$ (crystallization temperature) are 716K and 765K for the Cu base powder, but 836K and 890K for the Ni base ones, respectively. SPS process was used to consolidate the mixture of each amorphous powder, being $CuA/10\%NiA\;and\;NiA/10\%CuA$ in weight. The resultant phases were Cu crystalline dispersed NiA matrix composites as well as NiA phase dispersed CuA matrix composites, depending on the SPS temperatures. Effect of the second phases embedded in the MG matrix was discussed on the micro-structure and mechanical properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.330-337
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• 2005

La/sub 0.8/Sr/sub 0.2/Ga/sub 0.8/Mg/sub 0.2/O/sub 3-δ/-based solid electrolytes in which Mg site was partially substituted by Fe, Co or Ni (0.05, 0.1, 0.15 at.％) were fabricated by conventional solid-state reaction and their sintered densities were above 94％ of theoretical density. X-ray diffraction analysis and microstructure observation for the sintered specimens were performed. The ac complex impedance were measured at 400。C to l000。C in air and fitted with a Solatron ZView program. The electrical conductivity of La/sub 0.8/Sr/sub 0.2/Ga/sub 0.8/Mg/sub 0.2/O/sub 3-δ/-based solid electrolytes substituted by Fe, Co or Ni was higher than that of pure La/sub 0.8/Sr/sub 0.2/Ga/sub 0.8/Mg/sub 0.2/O/sub 3-δ/. The electrical conductivity of La/sub 0.8/Sr/sub 0.2/Ga/sub 0.8/Mg/sub 0.05/Ni/sub 0.15/O/sub 3-δ/ electrolyte was 3.4×10/sup -2/ Scm/sup -1/ at 800。C and the highest value of the whole electrolytes.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.248-254
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• 2006

The promotion effects of noble metals upon the activity and reducibility in steam methane reforming over $Ni/MgAl_2O_4$ catalysts were investigated. While $Ni/MgAl_2O_4$ catalysts require the pre-reduction by $H_2$, the noble metal-added catalysts show high catalytic activities without pre-treatment. According to $CH_4$-TPR, the addition of noble metal makes the $Ni/MgAl_2O_4$ catalyst easily reducible. The reduction degree of NiO in the noble metal-added catalysts after using at $650^{\circ}C$ without pre-reduction was $15{\sim}20%$, and was lower than that in the $H_2$-reduced $Ni/MgAl_2O_4$ catalyst(reduction degree=27%). The enhancement of the catalytic activity over noble metal-added catalysts results from easier reducibility by addition of noble metal and the synergy effect between noble metal and Ni.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.2
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• pp.148-157
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• 2022

Research on hydrogen storage is active to properly deal with hydrogen, which is considered a next-generation energy medium. In particular, research on metal hydride with excellent safety and energy efficiency has attracted attention, and among them, magnesium-based hydrogen storage alloys have been studied for a long time due to their high storage density, low cost, and abundance. However, Mg-based alloys require high temperature conditions due to strong binding enthalpy, and have many difficulties due to slow hydrogenation kinetics and reduction in hydrogen storage capacity due to oxidation, and various strategies have been proposed for this. This research manufactured Mg₂Ni to improve hydrogenation kinetics and synthesize about 5, 10, 20 wt% of CaF₂ as a catalyst for controlling oxidation. Mg₂NiHx-CaF₂ produced by hydrogen induced mechanical alloying analyzed hydrogenation kinetics through an automatic PCT measurement system under conditions of 423 K, 523 K, and 623 K. In addition, material life cycle assessment was conducted through Gabi software and CML 2001 and Eco-Indicator 99' methodology, and the environmental impact characteristics of the manufacturing process of the composites were analyzed. In conclusion, it was found that the effects of resource depletion (ARD) and fossil fuels had a higher burden than other impact categories.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.8-18
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• 2022

With rapid industrialization and population growth, fossil fuel use has increased, which has a significant impact on the environment. Hydrogen does not cause contamination in the energy production process, so it seems to be a solution, but it is essential to find an appropriate storage method due to its low efficiency. In this study, Mg-based alloys capable of ensuring safety and high volume and hydrogen storage density per weight was studied, and Mg₂NiH_x synthesized with Ni capable of improving hydrogenation kinetics. In addition, in order to improve thermal stability, a hydrogen storage composite material synthesized with CaO was synthesized to analyze the change in hydrogenation reaction. In order to analyze the changes in the metallurgical properties of the materials through the process, XRD, SEM, BET, etc. were conducted, and hydrogenation behavior was confirmed by TGA and hydrogenation kinetics analysis. In addition, in order to evaluate the impact of the process on the environment, the environmental impact was evaluated through "Material Life Cycle Assessments" based on CML 2001 and EI99' methodologies, and compared and analyzed with previous studies. As a result, the synthesis of CaO caused additional power consumption, which had a significant impact on global warming, and further research is required to improve this.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.46-52
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• 2006

The effects of surface treatment on the hydrogen storage properties of a $Mg_2Ni$ alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle in a KOH aqueous solution. It was found that the hydrogen storage properties of $Mg_2Ni$ at room temperature were improved by the surface treatment with a nickel plating solution. The sodium salts(sodium phosphate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen charge/discharge capacity at room temperature as high as about 150[mAh/g] from the original value of 17[mAh/g]. Potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-8}{\sim}10^{-9}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.389-394
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• 2006

Mg and Mg-based alloys are promising hydrogen storage alloys for renewable clean energy applications. It is a lightweight and low cost material with high hydrogen storage capacity. However, commercial applications of the Mg hydride are currently hindered by its high absorption/desorption temperature, and very slow reaction kinetics. In this work, we aim to study the absorption properties of the $Mg_2Ni$-5mass% Nb composite prepared by mechanical alloying under hydrogen. The absorption capacity of the sample is found to be about 3.0 wt.% at T=573 K and P=1.0 MPa. The absorption characteristics observed have been compared with those of the prepared $Mg_2Ni$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.747-750
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• 2003

The microstructure and nonlinear properties of ZPCMR-based varistors were investigated with various additives. The density of varistors were gradually decreased for the same R in order of NiO, MgO, and $Cr_2O_3$, respectively. The ZPCR-based varistors were not affected by NiO and MgO additives in nonlinear properties, whereas greatly affected by $Cr_2O_3$. Among the ZPCCR-based varistors, ZPCCD varistor exhibited the highest nonlinear properties, in which the nonlinear exponent is in the range of $40.5{\sim}67.4$ and the leakage current is in the range of $1.2{\sim}2.7{\mu}A$.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.612-623
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• 2020

This study was initiated to quantitatively evaluate the inhibitory effects of five heavy metals (Cd, Cu, Zn, Pb, Ni) on bacterial growth and phosphorus removal in the binary culture of Alcaligenes sp. plus Pseudomonas sp. IC50 values of Alcaligenes sp. plus Pseudomonas sp. for Cd, Cu, Zn, Pb, and Ni were 0.75, 10.93, 7.08, 13.30, and 15.78 mg/L, respectively. For the binary treatments of heavy metals, IC50 was the lowest in the treatment of Cd + Cu, whereas, it was the highest in the Ni + Pb treatment. The EC50 values for Cd, Cu, Zn, Pb, and Ni were 0.54, 11.08, 6.14, 9.33, and 13.81 mg/L, respectively. For the binary treatments of heavy metals, EC50 was the lowest in the Cd + Zn, whereas, the highest in the Zn + Ni. Based on both IC50 and EC50 values for the binary culture of bacteria with the binary mixtures of heavy metals, the most interactive effect was found to be antagonistic, though the only synergistic effect was found in Cu + Ni treatment. Therefore, our results can provide basic data on the toxic effects of heavy metals on the bacterial growth and phosphorus removal in the wastewater treatment process.