• 상하수도학회지
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• 제27권5호
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• pp.631-639
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• 2013

국내 하수처리장 인 방류기준이 강화되어 다양한 방법의 인 제거기술이 적용되고 있다. 흡착은 비교적 간단하면서 효과적으로 인을 제거할 수 있다. 본 연구에서는 흡착제인 Fe-Mn-Si oxide와 Fe-Mn oxide을 개발하여, 인 제거효율을 검토하였으며 이 흡착제에 대하여 Kinetic과 Isotherm모델을 비교하였다. 두 흡착제의 최대흡착양은 각각 47.8, 35.5 mg-$PO{_4}^{3-}/g$이었고, 이들은 낮은 pH에서 효과적으로 흡착하였다. Freundlish isotherm 모델이 Langmuir 모델보다 Fe-Mn-Si oxide의 흡착에 더 적합했다. 이온성 용액은 인이 흡착되는 과정에서 음이온들과 경쟁관계로 흡착능이 감소되었다. 비록 음이온과 humic물질들로부터 흡착에 영향을 받지만 Fe-Mn-Si oxide는 Fe-Mn oxide보다 흡착능이 크게 나타났다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2014년도 임시총회 및 하계학술연구발표회
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• pp.148-148
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• 2014

• 한국주조공학회지
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• 제10권2호
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• pp.154-161
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• 1990

The microstructures of sintered products of $Fe_2O_3$or $Fe_3O_4$-Oxide added cast iron powder was investigated. And the effects of particle size distribution was investigated too. As the result, the structures of sintered products did not related to the species of Fe-Oxide. Th porosity of sintered products was decreased in size and spherodized with increasing sintering temperature, decreasing Fe-Oxide quantity. Fe-Oxide itself did not hinder sintering of cast iron powder particularly, therefore sintering could be occurred without termination of reduction of it. And the sintered products of finer particle size distribution had finer and more spherodized porosity, and had minimized the deviation of size and shape of porosity.

• 대한토목학회논문집
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• 제28권1B호
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• pp.149-152
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• 2008

철의 환원 특성에 관한 연구는 이미 널리 수행되었으며 특히 미네랄과 2가철의 반응 메커니즘은 2가철의 흡착이나 바운드를 통해 Fe(II)-Fe(III) (hydr)oxides를 생성하여 2가철이 3가철로 산화됨으로써 물질을 환원시키는 것으로 받아들여지고 있다. 그러나 2가철로 개질된 재강슬래그를 이용한 DS/S 실험과정에서 이러한 메커니즘으로 설명하기 힘든 현상을 발견하였다. 재강슬래그의 주요 성분중의 하나인 FeO와 Fe(II)만을 이용하여 TCE의 분해과정을 실험해 본 결과 초기 TCE의 분해가 이루어지지 않다가 급속히 분해되는 현상을 보였으며 이러한 시스템에서 TCE의 분해는 예상치 못한 결과였다. FeO/Fe(II) 시스템은 3가철이 존재하지 않기 때문에 기존의 Fe(II)-Fe(III) (hydr)oxides를 형성하는 환원 메커니즘으로는 설명할 수 없었다. 따라서 본 연구에서는 TCE의 분해실험과 분해 부산물의 측정, 2가철과 3가철을 확인함으로써 FeO/Fe(II) 시스템의 환원특성을 확인해 보고자 하였다. 실험 결과 2가철이 FeO에 흡착 또는 바운드 되는 것을 확인 할 수 는 있었으나 기존의 메커니즘으로 설명하기에는 부족한 부분이 있었다. 분해부산물들을 통해 환원으로 인한 TCE의 분해는 의심의 여지가 없었으나 FeO/Fe(II) 시스템이 새로운 species를 형성하는지, 혹은 FeO에 Fe(II)가 흡착 또는 바운드 되어 이제껏 알려지지 않은 형태의 새로운 미네랄 상을 형성하는지는 좀 더 상세한 연구가 필요하다.

• 한국표면공학회지
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• 제32권4호
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• pp.538-546
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• 1999

Ti(IV)-Fe(III) oxide films were formed by MOCVD technique, and their photoelectrochemical properties were examined in 0.5M N $a_2$$SO_4$ solution by a photoelectrochemical polarization test. Ti(IV)-Fe(III) oxide films deposited at 40$0^{\circ}C$ by MOCVD have crystalline structure and are all n-type semiconductors. The photocurrent and the quantum efficiency of the films increase with increasing the iron cationic fraction ($X_{Fe}$ ) in the films. The energy band gap of the films increase linearly with increasing the iron cationic fraction in the films. Ti(IV)-Fe(III) oxide film of $X_{Fe}$ /=0.60 has high photocurrent response and corrosion resistance simultaneously.

• 한국재료학회지
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• 제12권11호
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• pp.845-849
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• 2002

Alloys of $Fe_3$Al, $Fe_3$Al-6Cr, $Fe_3$Al-4Cr-1Mo, $Ni_3$Al, and $Ni_3$Al-2.8Cr were oxidized at $1000^{\circ}C$ in air, and the oxide scales formed were studied using XRD. SEM, EPMA, and TEM. The oxide scales that formed on $Fe_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$ containing a small amount of dissolved Fe and Cr ions, whereas those that formed on $Ni_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$, together with a small amount of $NiAl_2$$O_4$, NiO and dissolved Cr ions. For the entire alloys tested, nonadherent oxide scales formed, and voids were inevitably existed at the scale-matrix interface.

• Carbon letters
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• 제13권3호
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• pp.157-160
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• 2012

In this work, iron oxide ($Fe_3O_4$) nanoparticles were deposited on multi-walled carbon nanotubes (MWNTs) by a simple chemical coprecipitation method and $Fe_3O_4$-decorated MWNTs (Fe-MWNTs)/polypyrrole (PPy) nanocomposites (Fe-MWNTs/PPy) were prepared by oxidation polymerization. The effect of the PPy on the electrochemical properties of the Fe-MWNTs was investigated. The structures characteristics and surface properties of MWNTs, Fe-MWNTs, and Fe-MWNTs/PPy were characterized by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The electrochemical performances of MWNTs, Fe-MWNTs, and Fe-MWNTs/PPy were determined by cyclic voltammetry and galvanostatic charge/discharge characteristics in a 1.0 M sodium sulfite electrolyte. The results showed that the Fe-MWNTs/PPy electrode had typical pseudo-capacitive behavior and a specific capacitance significantly greater than that of the Fe-MWNT electrode, indicating an enhanced electrochemical performance of the Fe-MWNTs/PPy due to their high electrical properties.

• Corrosion Science and Technology
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• 제13권2호
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• pp.41-47
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• 2014

The isothermal corrosion tests of several types of stainless steels, Ni-based alloys, and ferritic-martensitic steels (FMS) were carried out at the temperature of 550 and $650^{\circ}C$ in SFR S-$CO_2$ environment (200 bar) for 1000 h. The weight gain was greater in the order of FMSs, stainless steels, and Ni-based alloys. For the FMSs (Fe-based with low Cr content), a thick outer Fe oxide, a middle (Fe,Cr)-rich oxide, and an inner (Cr,Fe)-rich oxide were formed. They showed significant weight gains at both 550 and $650^{\circ}C$. In the case of austenitic stainless steels (Fe-based) such as SS 316H and 316LN (18 wt.% Cr), the corrosion resistance was dependent on test temperatures except SS 310S (25 wt.% Cr). After corrosion test at $650^{\circ}C$, a large increase in weight gain was observed with the formation of outer thick Fe oxide and inner (Cr,Fe)-rich oxide. However, at $550^{\circ}C$, a thin Cr-rich oxide was mainly developed along with partially distributed small and nodular shaped Fe oxides. Meanwhile, for the Ni-based alloys (16-28 wt.% Cr), a very thin Cr-rich oxide was developed at both test temperatures. The superior corrosion resistance of high Cr or Ni-based alloys in the high temperature S-$CO_2$ environment was attributed to the formation of thin Cr-rich oxide on the surface of the materials.

• 한국분말재료학회지
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• 제8권1호
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• pp.49-54
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• 2001

The synthesis and characteristics of W-Ni-Fe nanocomposite powder by hydrogen reduction of ball milled W-Ni-Fe oxide mixture were investigated. The ball milled oxide mixture was prepared by high energy attrition milling of W blue powder, NiO and $Fe_2O_3$ for 1 h. The structure of the oxide mixture was characteristic of nano porous agglomerate composite powder consisting of nanoscale particles and pores which act as effective removal path of water vapor during hydrogen reduction process. The reduction experiment showed that the reduction reaction starts from NiO, followed by $Fe_2O_3$ and finally W oxide. It was also found that during the reduction process rapid alloying of Ni-Fe yielded the formation of $\gamma$-Ni-Fe. After reduction at 80$0^{\circ}C$ for 1 h, the nano-composite powder of W-4.57Ni-2.34Fe comprising W and $\gamma$-Ni-Fe phases was produced, of which grain size was35nm for W and 87 nm for $\gamma$-Ni-Fe, respectively. Sinterability of the W heavy alloy nanopowder showing full density and sound microstructure under the condition of 147$0^{\circ}C$/20 min is thought to be suitable for raw material for powder injection molding of tungsten heavy alloy.

• 한국자기학회지
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• 제22권5호
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• pp.167-172
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• 2012

본 연구에서는 $Fe(OL)_3$ 전구체가 고온에서 열분해 한 후 산화철 나노입자를 형성하는 메커니즘을 분석하기 위하여 전구체의 온도에 따른 열유속을 측정하였으며, 반응 과정에서 순차적으로 채취한 반응 원액의 TEM 및 교류 자화율을 측정 하였다. $Fe(OL)_3$는 고온에서 OL-chain 두 개가 순차적으로 분리되어 Fe-OL 단량체(monomer)가 되고, 이들이 산화철 나노입자 형성에 기여하게 된다. 또한 산화철 나노입자는 초기 성장 과정에서 ${\gamma}-Fe_2O_3$ 구조를 갖는 나노입자를 형성하지만, 나노 입자들이 급격히 성장할 때는 공급되는 산소량의 부족으로 인하여 FeO가 형성되어 ${\gamma}-Fe_2O_3$-FeO의 core-shell 구조를 갖는 나노입자들이 합성된다. 이러한 산화철 나노입자들을 고온에서 장시간 유지시키면 부족한 산소를 점차적으로 보충하여 $Fe_3O_4$ 구조를 갖는 나노입자로 변화한다. 따라서 포화자화량이 높고 공기 중에서 안정한 $Fe_3O_4$ 나노입자는 고온 열분해법을 이용하여 쉽게 제조할 수 있다.