• 한국결정성장학회지
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• 제28권2호
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• pp.85-90
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• 2018

폐니켈수소전지에 함유되어 있는 희토류를 회수하기 위하여 $H_2SO_4$로 침출한 용액에 10 M NaOH를 첨가하여 희토류를 pH 2.0 이하에서 약 98 % 침전시켰다. 이후 회수된 희토류 복합 침전물은 $800^{\circ}C$에서 4시간 동안 열처리를 통해 $HNO_3$에 대한 침출률을 증가시켰으며, 희토류 복합 침전물이 용해된 용액에 oxalic acid를 첨가하여 2차 침전을 실시하였다. 재침전된 희토류는 다시 $800^{\circ}C$에서 4시간 열처리를 통해 산화물 형태로 변환되었으며, 이때 희토류 산화물의 순도는 약 99.5 %를 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.402.1-402.1
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• 2016

The performance of solid oxide fuel cells (SOFCs) is directly related to the electrocatalytic activity of composite electrodes in which triple phase boundaries (TPBs) of metallic catalyst, oxygen ion conducting support, and gas should be three-dimensionally maximized. The distribution morphology of catalytic nanoparticle dispersed on external surfaces is of key importance for maximized TPBs. Herein in situ grown nickel nanoparticle onto the surface of fluorite oxide is demonstrated employing gadolium-nickel co-doped ceria ($Gd0.2-xNixCe0.8O2-{\delta}$, GNDC) by reductive annealing. GNDC powders were synthesized via a Pechini-type sol-gel process while maximum doping ratio of Ni into the cerium oxide was defined by X-ray diffraction. Subsequently, NiO-GNDC composite were screen printed on the both sides of yttrium-stabilized zirconia (YSZ) pellet to fabricate the symmetrical half cells. Electrochemical impedance spectroscopy (EIS) showed that the polarization resistance was decreased when it was compared to conventional Ni-GDC anode and this effect became greater at lower temperature. Ex situ microstructural analysis using scanning electron microscopy after the reductive annealing exhibited the exsolution of Ni nanoparticles on the fluorite phases. The influence of Ni contents in GNDC on polarization characteristics of anodes were examined by EIS under H2/H2O atmosphere. Finally, the addition of optimized GNDC into the anode functional layer (AFL) dramatically enhanced cell performance of anode-supported coin cells.

• 한국분말재료학회지
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• 제18권5호
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• pp.456-462
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• 2011

Yttrium oxide is one of the most thermo-dynamically stable materials, so that it is generally used as a dispersoid in many kinds of dispersion strengthed alloys. In this study, a nickel-base superalloy is strengthened by dispersion of yttrium oxide particles. Elemental powders with the composition of Ni-22Cr-18Fe-9Mo were mechanically alloyed(M.A.) with 0.6 wt% $Y_2O_3$. The MA powders were then HIP(hot isotactic press)ed and hot rolled. Most oxide particles in Ni-22Cr-18Fe-9Mo base ODS alloy were found to be Y-Ti-O type. The oxide particles were uniformly dispersed in the matrix and also on the grain boundaries. Tensile test results show that the yield strength and ultimate tensile strength of ODS alloy specimens were 1.2~1.7 times higher than those of the conventional $Hastelloy^{TM}$ X(R), which has the same chemical compositions with ODS alloy specimens except the oxide particles.

• International Journal of Safety
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• 제1권1호
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• pp.58-61
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• 2002

A preparation method of cobalt supported alumina catalyst for a emergency escape mask cartridge has been studied. Catalysts were prepared by incipient wetness impregnation method using pre-shaped $\gamma$=alumina powders of 70-100 mesh. The catalyst was tested in a continuous-flow reactor system and characterized by elemental analysis, BET and TGA-DTA techniques. Cobalt shows higher activity than platinum or nickel for carbon monoxide oxidation at room temperature. Optimum loading amount of cobalt was 10 wt.% for CO oxidation and the reaction activity increases gradually with the increase of calcination temperature up to $450^{\circ}C.

• 한국전기전자재료학회논문지
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• 제23권9호
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• pp.736-740
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• 2010

Nickel wires of 0.8 mm in diameter and 80 mm in length were electrically exploded in liquid media such as water, ethyl alcohol. The distribution of particle sizes was broad from a few micrometers to tens of nanometer. It was identified that the particles could be classified according to its sizes by using centrifugal separator. The powder prepared in distilled water showed mainly pure metallic Ni phase although a little oxide phase was observed. The powders prepared in ethyl alcohol showed complicated unknown phases, which is attributed to the compound of carbon in the organic liquid. This unknown phase was turned to pure metallic Ni phase after heat treatment.

• 한국세라믹학회지
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• 제38권12호
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• pp.1162-1166
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• 2001

석유화학 공정 중 Styrene(SM) 공정에서 발생되는 산화철 폐촉매는 산업 폐기물로서 전량 매립되고 있는데, 이를 출발 원료로 사용하여 NiZn-페라이트를 합성하였고 그 자기적 특성을 조사하였다. 산화철 폐축매 펠렛을 분쇄한 후 NiO 및 ZnO를 혼합하여 90$0^{\circ}C$에서 하소하고 123$0^{\circ}C$에서 5시간 소결하여 스핀넬형 페라이트 소결체를 얻었다. N $i_{x}$ Z $n_{1-x}$F $e_2$ $O_4$(x=0.36, 0.50, 0.66)조성에 대하여 초투자율을 측정하였고, S-parameter를 측정하여 반사 감쇄량을 계산하였다. 산화철 폐촉매를 이용하여 X-band 주파수 영역에서 높은 전자파 흡수능을 갖는 전파흡수체를 제조할 수 있음을 확인하였다.다.

• 한국결정학회지
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• 제14권1호
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• pp.1-6
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• 2003

석유화학 공정 중 styrene monomer제조공정에서 발생되는 산화철 폐촉매는 산업 폐기물로서 전량 매립되고 있는데, 이를 출발원료로 사용하여 NiZn-페라이트를 합성하였고, 그 자기적 특성을 조사하였다. 출발 원료인 산화철 폐촉매는 산 처리와 CeO₂ 분리과정을 거쳤으며, 이렇게 정제된 산화철 폐촉매에 NiO및 ZnO를 혼합하여 900℃에서 하소하여 스핀넬형 페라이트를 합성하고 1325℃에서 5시간 소결하였다. Ni/sub x/Zn/sub 1-x/Fe₂O₄(x=0.36, 0.50, 0.66)과 (Ni/sub 0.5/Zn/sub 0.5/)/sub 1-y/Fe/sub 2+y/O₄(y =-0.02, 0, 0.02)의 조성에 대하여 초투자율을 측정하였고, S-parameter를 측정하여 반사 감쇄량을 계산하였다.

• 자원리싸이클링
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• 제22권4호
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• pp.62-69
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• 2013

$Li(NCM)O_2$계 폐리튬전지 공정 스크랩의 재활용 연구의 일환으로서 리튬화합물의 회수와 NCM전구체를 제조하기 위한 침출거동에 대하여 살펴보았다. 우선 탄소를 이용하여 층상 구조의 NCM계 산화물 분말을 분해시켰으며, $600^{\circ}C$ 이상의 탄소반응으로 리튬은 탄산리튬으로 변화시켰다. 탄산리튬은 수세 후 농축과정을 거쳐 순도 99% 이상의 탄산리튬 분말로 회수하였다. 그리고 탄소에 의한 환원 반응율은 $800^{\circ}C$에서 약 88%을 나타내었으며, 탄소환원 처리 후 분말에 대한 황산 침출 결과, 2M 이상의 황산농도에서 코발트, 니켈, 망간의 침출율은 99% 이상이었다.

• 한국분말재료학회지
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• 제7권4호
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• pp.237-243
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• 2000

The property and performance of the $Al_2O_3/Ni$ nanocomposites have been known to strongly depend on the structural feature of Ni nanodispersoids which affects considerably the structure of matrix. Such nanodispersoids undergo structural evolution in the process of consolidation. Thus, it is very important to understand the microstructural development of Ni nanodispersoids depending on the structure change of the matrix by consolidation. The present investigation has focused on the growth mechanism of Ni nanodispersoids in the initial stage of sintering. $Al_2O_3/Ni$ powder mixtures were prepared by wet ball milling and hydrogen reduction of $Al_2O_3$ and Ni oxide powders. Microstructural development and the growth mechanism of Ni dispersion during isothermal sintering were investigated depending on the porosity and structure of powder compacts. The growth mechanism of Ni was discussed based upon the reported kinetic mechanisms. It is found that the growth mechanism is closely related to the structural change of the compacts that affect material transport for coarsening. The result revealed that with decreasing porosity by consolidation the growth mechanism of Ni nanoparticles is changed from the migration-coalescence process to the interparticle transport mechanism.

• 한국산업보건학회지
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• 제26권2호
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• pp.225-236
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• 2016

Objectives: Nanomaterials have been used in various fields. As use of nanoproducts is increasing, workers dealing with nanomaterials are also gradually increasing. Exposure assessments for nanomaterials have been carried out for protection of worker's health in workplace. Exposure studies were mainly focused on manufacturing processes, but these studies on after-treatment processes such as refinement, weighing, and packing were insufficient. So, we investigated exposure characteristics of particles during after-treatment processes of $Al_2O_3$ fibers and Ni powders. Methods: Mass-production of Ni powder process was carried out in enclosed capture-type canopy hood. In a developing stage, $Al_2O_3$ was handled with a local ventilation unit. Exposure characteristics of particles were investigated for $Al_2O_3$ fiber and Ni powder processes during the periods of 10:00 to 16:00, 20 May 2014 and 13:00 to 16:00, 21 May 2014, respectively. Three real-time aerosol instruments were utilized in exposure assessment. A scanning mobility particle sizer(SMPS, nanoscan, model 3910, TSI) and an optical particle counter(OPC, portable aerosol spectrometer, model 1.109, Grimm) were used to determine the particle size distribution in the size range of 10-420 nm and $0.25-32{\mu}m$, respectively. In addition, a nanoparticle aerosol monitor(NAM, model 9000, TSI) was used to measure lung-deposited nanoparticle surface area. Membrane filters(isopore membrane filter, pore size of 100 nm) were also used for air sampling for the FE-SEM(model S-5000H, Hitachi) analysis using a personal sampling pump(model GilAir Plus by 2.5 L/min, Gilian). Conclusions: For Ni powder after-treatment process, only 27% increase in particle concentration was found during the process. However, for $Al_2O_3$ fiber after-treatment process, significant exposure(1.56-3.34 times) was observed during the process.