• 자원리싸이클링
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• 제2권2호
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• pp.1-8
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• 1993

부선법에 의하여 폐수속에 함유되어 있는 철이온을 제거하기 위한 몇가지 효과적인 포수제와 최적 조건들을 알아본 실험의 결과를 요약하면 다음과 같다. 음이온 포수제인 sodium lauryl sulfate에 의해서 2가와 3가 철은 각각 pH 7과 6에서 효과적으로 제거되었다. 음이온 호수제인 aeropromotor 845에 의해서 2가와 3가철은 모두 pH pH 10~11영역에서, 3가철은 pH4~10영역에서 효과적으로 제거되었따. 따라서, 2가와 3가철은 2가와 3가 철이온침전점 이상으로 단순히 용액의 pH값을 조절하여 수산화철 침전으로 만든 다음 부선법에 의하여 효과적으로 제거된다고 할 수 있다. 그때의 효과적은 pH 조절제는 NaOH와 $Na_2CO_3$였고, 효과적인 포수제는 aeropromotor 845와 trimetyl dodecyl ammomum chloride 이었다.

• Korean Chemical Engineering Research
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• 제55권5호
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• pp.679-684
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• 2017

Fe/BEA 제올라이트 촉매의 $N_2O/NO$ 동시 환원반응에서 Fe이온을 담지하는 방법이 촉매의 활성에 미치는 영향을 고찰하였다. Fe/BEA 제올라이트 촉매는 함침법과 이온교환법으로 제조되었으며, 제조된 촉매의 성능을 확인하기 위하여 암모니아를 환원제로 사용하는 선택적 촉매 환원 반응을 실시하였다. 그 결과 이온교환 촉매는 함침 촉매보다 높은 NO 및 $N_2O$ 전환율을 나타내었다. 이러한 촉매 활성의 차이를 규명하기 위하여 XRD, $H_2-TPR$, $O_2-TPD$, XPS와 같은 촉매 특성 분석들이 수행되었다. 이온교환 촉매의 활성 증가는 향상된 환원 특성 및 증가된 산소 탈착 속도에 기인한 것으로 판단되며, 이온교환 촉매 제조시 촉매 활성과 관련이 있는 $Fe^{2+}$가 함침 촉매에 비해 약 1.6배 이상 형성되는 것을 XPS 분석을 통하여 확인하였다.

• 한국재료학회지
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• 제12권1호
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• pp.44-47
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• 2002

DV(Discrete Variation)-X${\alpha}$ cluster calculation was employed to calculate the electronic states of ${\gamma}'- Fe_4N$ which was one of iron nitride phases synthesized from plasma ion nitriding to improve surface hardness and wear resistance. The result of calculated electron density of states for Fe was similar to the result of band calculation. The cluster used for calculation of electronic states of ${\gamma}'-Fe_4N$ was based on $Fe_{14}N$ cluster which comprises 15 atoms. Finally the electronic states of ${\gamma}'- Fe_4N$ such as net-charge, band order, energy level, electron wave-function, and contour map for electron density were derived by the calculation.

• Applied Science and Convergence Technology
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• 제27권3호
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• pp.47-51
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• 2018

We fabricated an anode-type ion beam source and studied its driving characteristics of the initial extraction of ions using two driving mechanisms: a diffusion phenomenon and a charge repulsion phenomenon. For specimen exposed to the ion beam in two methods, the surface impurity element was investigated by using X-ray photoelectron spectroscopy. Upon Ar gas injection for plasma generation the ion beam source was operated for 48 hours. We found a Fe 2p peak 5.4 at. % in the initial ions by the diffusion mechanism while no indication of Fe in the ions released in the charge repulsion mechanism. As for a long operation of 200 min, the temperature of ion beam sources was measured to increase at the rate of ${\sim}0.1^{\circ}C/min$ and kept at the initial value of $27^{\circ}C$ for driving by diffusion and charge repulsion mechanism, respectively. In this study, we confirmed that the ion beam source driven by the charge repulsion mechanism was very efficient for a long operation as proved by little electrode damage and thermal stability.

• 열처리공학회지
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• 제9권1호
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• pp.69-77
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• 1996

The fatigue crack initiation behavior of plasma ion nitrided SACM645 steel was investigated through the rotary bending fatigue test and residual stress measurement by XRD. It was shown by XRD and EPMA that the plasma ion nitrided surface was composed of ${\gamma}^{\prime}(Fe_4N)$phase and ${\varepsilon}(Fe_{2-3}N)$phase, and that the nitrogen atoms existed in Fe matrix in diffusion layer. The OM, SEM and Auger spectroscopy showed that the depth of compound layer, mixed compound and diffusion layer, and diffusion layer was $8{\mu}m$, $30{\mu}m$ and $300{\mu}m$, respectively. However, the microhardness test showed that the depth of hardened layer was $500{\mu}m$. The tensile strength of the ion nitrided SACM645 was lower than that of the unnitrided SACM645, and the ion nitrided specimen was fractured without plastic deformation. The nitrided SACM645 showed much poorer low cycle fatigue properties than the unnitrided one. In rotary bending fatigue, the fatigue strength of the ion nitrided SACM645 was higher than that of the unnitrided specimen, and the fatigue crack initiation sites changed by applied fatigue stress levels. The XRD result showed that the ion nitrided SACM645 has the compressive residual stress from surface to $600{\mu}m$ deep and the tensile residual stress from $600{\mu}m$ to deeper site. It is thought that crack initiation takes place at the point where the total stress of residual stress and applied stress is maximum.

• 한국세라믹학회지
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• 제53권3호
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• pp.376-380
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• 2016

A composite electrode made of iron oxide nanoparticles/multi-wall carbon nanotube (iNPs/M) delivers high specific capacity and cycle durability. At a rate of $200mAg^{-1}$, the electrode shows a high discharge capacity of ${\sim}664mAhg^{-1}$ after 100 cycles, which is ~ 70% of the theoretical capacity of $Fe_3O_4$. Carbon black, carbon nanotube, and graphene as anode materials have been explored to improve the electrical conductivity and cycle stability in Li ion batteries. Herein, iron oxide nanoparticles on acid treated MWCNTs as a conductive platform are combined to enhance the drawbacks of $Fe_3O_4$ such as low electrical conductivity and volume expansion during the alloying/dealloying process. Enhanced performance was achieved due to a synergistic effect between electrically 3D networks of conductive MWCNTs and the high Li ion storage ability of $Fe_3O_4$ nanoparticles (iNPs).

• 한국표면공학회지
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• 제44권4호
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• pp.149-154
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• 2011

Martensitic stainless steel STS 431 has been nitrided by active screen ion nitriding under the various temperature and time. The thickness of diffusion layer, case depth, hardness and composition phases were investigated using field emission scanning electron microscopy (FE-SEM), micro-Vickers hardness tester, X-ray diffraction (XRD) and glow discharge spectroscopy (GDS). It was observed that the thickness of diffusion layer depends strongly on the treatment temperature and time. A sample, which was nitrided at $450^{\circ}C$ for 8hours, was a maximum hardness of Hv0.01 1558 and nitride layer of $70{\mu}m$. As shown in XRD patterns, $\varepsilon(Fe_{2-3}N)$ and expanded martensite (${\alpha}_N$) phases which was saturated with nitrogen solid solution were in the nitrided layer treated at $450^{\circ}C$ for 2 hours. Composition phases of $\varepsilon$ $(Fe_{2-3}N)$ and ${\gamma}'$ ($Fe_4N$) were observed after active screen nitriding at $450^{\circ}C$ for 8 hours.

• 대한화학회지
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• 제68권3호
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• 대한화학회지
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• 제19권5호
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• pp.325-330
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• 1975

철(III) 이온과 인산간의 착물형성에 관하여 넓은 인산산성범위(0${\sim}40{\%}$)에서 가시부스펙트럼과 용액으로 부터 분리해낸 화합물을 검토함으로써 연구하였다. 철(III)함유 인산용액의 전자흡수 스펙트럼은 19.2kK 및 24.1kK에서 철(III)-인산 착물형성을 나타내는 두개의 가시부 흡수를 나타내었다. 24.1kK 밴드의 인산농도에 따른 흡광도 변화의 측정으로부터 아마도 $[Fe(H_xPO_4)]^{x+}\;및\;[Fe_2 (H_xPO_4)]^{(3+x)+}$등 두개의 형태가 틀린 철(III)-인산착물이 존재함을 알 수 있었다. 이들 두화합물중 몰비가 1:1인 착물은 고체상태로 분리하는데 성공하였으며 인산이온은 염기도 1인 상태로 금속에 배위되어 있음을 알 수 있으나, 이합체로 생각되는 화합물은 분리해낼 수 없었다.

• Bulletin of the Korean Chemical Society
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• 제29권2호
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• pp.309-312
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• 2008

Two different anode composite materials comprising of Fe, Cu and Si prepared using high energy ball milling (HEBM) were explored for their capacity and cycling behaviors. Prepared powder composites in the ratio Cu:Fe:Si = 1:1:2.5 and 1:1:3.5 were characterized through X-Ray diffraction (XRD) and scanning electron microscope (SEM). Nevertheless, the XRD shows absence of any new alloy/compound formation upon ball milling, the elements present in Cu(1)Fe(1)Si(2.5)/Graphite composite along with insito generated Li2O demonstrate a superior anodic behavior and delivers a reversible capacity of 340 mAh/g with a high coulombic efficiency (98%). The higher silicon content Cu(1)Fe(1)Si(3.5) along with graphite could not sustain capacity with cycling possibly due to ineffective buffer action of the anode constituents.