• Title, Summary, Keyword: 분극저항

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Effect of YSZ Particle Size and Sintering Temperature on the Microstructure and Impedance Property of Ni-YSZ Anode for Solid Oxide Fuel Cell (고체산화물 연료전지용 Ni-YSZ 음극의 미세구조와 임피던스특성에 미치는 YSZ 입자크기 및 소결온도의 영향)

  • 김구대;문지웅;이기태;이홍림
    • Journal of the Korean Ceramic Society
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    • v.38 no.5
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    • pp.466-473
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    • 2001
  • Ni-YSZ 음극의 미세구조와 임피던스특성에 미치는 YSZ 입자크기 및 소결온도의 영향을 고찰하였다. 0.3~0.6$\mu\textrm{m}$의 미세한 NiO 분말을 사용할 경우에는 NiO 분말과 크기가 비슷한 미세한 YSZ 분말(TZ8Y, 0.3$\mu\textrm{m}$)을 첨가했을 때 NiO의 입성장을 억제하는 효과가 가장 크고 환원후 Ni의 입자크기를 미세하게 유지할 수 있는 미세구조를 형성하였다. 또한 미세한 YSZ 분말 (TZ8Y, 0.3$\mu\textrm{m}$)과 조대한 YSZ 분말(FYT13.0, 2$\mu\textrm{m}$)의 혼합비를 달리하여 후막을 제조하였을 때에 TZ8Y 분말만 첨가한 조성이 가장 낮은 분극 저항을 나타내었다. 한편 소결온도는 삼상계면의 양과 분극저항에 영향을 주었으며, 140$0^{\circ}C$에서 소결한 시편의 분극저항이 가장 낮은 값을 나타내었다.

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초내식성 오스테나이트계 스테인리스강의 증기발생기 전열관 적용가능성 평가

  • 김택준;박용수;김영식
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.201-206
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    • 1997
  • 본 연구에서는 Ni-기 합금인 합금 600과 합금 690, Fe-기 합금인 합금 800 및 초내식성 오스테나이트계 스테인리스강인 SR-50A에 대하여 부식 환경의 변화에 따른 특성 평가를 행하였다. 전기화학적 부식 평가는 양극 분극 시험을 통하여 행하였으며 부식 환경은 NaCl, HCI, NaOH(+$Na_2$SO$_4$) 액이었다. 응력 부식 균열 시험으로는 CERT(Constant Extension Rate Test)를 행하였으며 부식환경은 40%NaOH, 40%OH+12%$Na_2$SO$_4$ 용액이었다. CERT시험 후 그 파면을 SEM관찰하여 파괴 양상을 관찰하였다. 각 합금의 양극 분극 특성을 부식 환경에 따라 평가한 결과, 부식 용액의 증류에 따라 서로 다른 분극 거동을 보이고 있는데 산성과 중성 용액에서는 SR-50A가 가장 큰 저항성을 보이는 반면, 강 알카리용액인 NaOH용액에서는 Ni-기 합금의 저항성이 Fe-기 합금의 저항성보다 우수하게 나타났다. 응력 부식 균열 저항성은 전반적으로 Fe-기 합금보다 Ni-기 합금이 우수하게 나타났다. 파단면을 SEM관찰한 결과 합금 800과 SR-50A(tube)는 용액에 관계없이 입내 파괴 모드를 나타내고 있으며, 합금 600과 SR-50A판재는 입계 파괴 양상을 보이고 있다. 또한 가성 용액 중에 $Na_2$SO$_4$를 첨가할 경우, 부식 속도를 가속화시키고 응력 부식 균열 저항성을 감소시키고 있다.

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A Study on the Concentration Polarization Layer Resistance in Ultrafiltration of Macromolecular Solutions (고분자 용액의 한외여과에서 농도분극층 저항에 관한 연구)

  • 염경호
    • Membrane Journal
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    • v.2 no.1
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    • pp.59-66
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    • 1992
  • The experimental studies were carried out on ultrafiltration of PEG #6000 and dextran 70T macromole¬cules. using an asymmetric cellulose acetate membrane in a cross flow plane type cell. Effects of pressure difference. feed concentration were studied on permeate flux and observed rejection for both the macromole¬cules. and the concentration polarization layer resistance $R_{b1}$ on permeate flux was analysed. The concentration polarization layer resistance $R_{b1}$ was correlated with the average macromolecule concen¬tration $C_{b1}$ in polarization layer. The resulting dimensionless correlation was expressed as : $\frac{R_{b1}}{{R_m}}=\alpha[\frac{\rho_{b1}}{C_{b1}}]^\beta$

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Recognition of Seawater Intrusion Using Reference IP Technique (참조채널 유도분극탐사기술에 의한 해수침투대 인지)

  • Lee, Sang-Kyu;Hwang, Hak-Soo;Hwang, Se-Ho;Park, In-Hwa;Shin, Je-Hyun
    • Geophysics and Geophysical Exploration
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    • v.5 no.1
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    • pp.56-63
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    • 2002
  • Tracing the history of study, problems of seawater intrusion are commonly investigated with electrical techniques because seawater saturated zone is indicative of the low resistivity anomaly. There we, however, silt and mud layers in the western and southern coastal areas of Korea, so we may make a mistake in case we determine seawater intrusion only with resistivity survey. Hence, reference IP survey was carried out in Kimje, Jeollabuk-Do and Youngkwang, Jeollanam-Do in order to decide whether or not the area is under the influence of seawater intrusion. With the use of a electric field cable to minimize EM coupling, we obtained more accurate results by appling reference If technique measuring simultaneously wavelet of current as well as potential. With the aid of reference IP technique, it is possible that we can exactly evaluate seawater intrusion by discriminating seawater saturated area (no IP effect) from very highly conductive layer composed of clay mineral (high IP effect).

Research on the Polarization Procedure Using PMS-PZT Piezoelectric Materials (PMS-PZT계 압전재료의 분극공정에 대한 연구)

  • Kim, H.S.;Kim, J.R.;Huh, J.S.;Lee, H.Y.;Oh, Y.W.;Park, H.Y.
    • Proceedings of the KIEE Conference
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    • pp.1609-1611
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    • 2004
  • 압전재료의 분극공정에서 제어되는 인가전압, 유지시간 및 온도 변수들에 대한 최적의 조건을 확립하기 위해 Rosen형 안전 변압기를 설계 및 제조하여 특성분석 하였다. 분극처리를 위한 분극전계, 온도, 유지시간 등의 외부 에너지가 증가할수록 쉽게 분극되어 포화현상이 나타났으며, 140$^{\circ}C$ 이상의 온도에서 4kV/mm의 분극전계로 3분 이상 분극시키면 최대 전압 이득을 얻을 수 있다. 또한 부하저항이 증가할수록 공진주파수는 고주파 방향으로 이동하며, 공진전류가 증가하여 전압이득이 증가하였다.

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An Experimental Study on Corrosion Behavior in Steel of Concrete Applied with Arc Metal Spray Method Surface Treatment Technology Using EIS (EIS를 이용한 아크 금속용사 표면처리기법이 적용된 강재의 콘크리트 내 부식 거동에 관한 실험적 연구)

  • Yoon, Chang-Bok;Park, Jang hyun;Lee, Han-Seung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.3
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    • pp.87-95
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    • 2020
  • As an experimental study on the corrosion behavior of steel materials to which ATMS method using EIS was applied in concrete, immersion of Ca(OH)2 saturated aqueous solution and NaCl aqueous solution simulating the environment inside concrete The corrosion behavior was tested. The equivalent circuit was derived through the analysis of the Nyquist plot, and the interfacial resistance and the polarization resistance of the Ca(OH)2 aqueous solution were compared, and Al ATMS was the best interfacial resistance and Zn ATMS was the best polarization resistance. After burying ATMS steel material of cement mortar, the initial immersion impedance measurement value was the highest in the Zn ATMS test body in the impedance measurement by the immersion time by immersing it in the NaCl aqueous solution. Al ATMS test piece has the highest impedance and is highly reliable. This is because Al, which has a high ionization tendency, is continuously oxidized in a strong alkaline environment to form a film and protect the steel from permeation of chlorine ions.

The Use of Galvanostatic Pulse Transient Techniques for Assessing of Corrosion Rate of Reinforcing steel in Concrete (정전류 펄스법을 이용한 콘크리트 내 보강철근의 부식 연구)

  • So, Hyoung-Seok
    • Journal of the Korea Concrete Institute
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    • v.19 no.6
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    • pp.785-793
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    • 2007
  • An electrochemical transient response technique was used to study the corrosion of reinforcing steel bar in the concrete. Analysis of the transient electrochemical potential response in a corrosion interface to an applied current has enabled the separate components that make up the measured transient response to be isolated. These components display a range of resistances and capacitances, dependent on the corrosion conditions of the reinforcing steel, which may be attributed to the corrosion process, to effects within the concrete cover or to film effects on the surface of the concrete. In this technique, the corrosion rate was evaluated by summing all of the resistances in the separate components to obtain an aggregated corrosion resistance. However, it is possible that not all resistances identified are associated with the corrosion process. The results obtained show that the corrosion rates are significant dependent on the assignment of the separate components to either corrosion or to other processes. The assignment of resistive components associated with the corrosion rate can be clearly identified by taking a series of the transient measurement at different lateral distances from the corroding reinforcing steel. An inappropriate selection of measurement time however may result in an additional resistance, which is not associated with corrosion, being included or part of the resistance associated with corrosion being left out.

Analysis of the Electromagnetic Scattering of Resistive Strip Grating with Uniform Resistivity on a Grounded Dielectric Layer - H-Polarization Case - (접지된 유전체 위의 저항율이 일정한 저항띠 격자구조에 대한 전자파 산란 해석 - H-분극인 경우 -)

  • Tchoi Young-Sun;Yang Seung-In
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.3A
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    • pp.321-327
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    • 2006
  • In this paper, when a H-polarized plane wave is incident on the grating consisting of uniform resistive strips, electromagnetic scattering is analyzed using the moment of methods (MoM). The current density of each resistive strip on a grounded dielectric plane is fixed by zero at both edges. To satisfy the condition at both ends of each resistive strip, the induced surface current density is expanded in a series of cosine and sine functions. The scattered electromagnetic fields are expanded in a series of floquet mode functions. The boundary conditions are applied to obtain the unknown current coefficients. According to the variation of the involving parameters such as strip width and spacing and angle of the incident field, numerical simulations are performed by applying the Fourier-Galerkin moment method. The numerical results of the normalized reflected power for resistive strips case for zero and several resistivities are obtained.

Macrocell and Microcell Corrosion of Reinforcing Steel in Concrete Immersed in Saltwater (염수 환경하에서 콘크리트내 철근의 마크로 및 마이크로 셀 부식)

  • 이재봉;이수열;정영수;이광명;정원기;배수호
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.211-214
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    • 1999
  • 염화물 및 방청제가 함유된 철근 콘크리트의 부식특성을 마크로 셀 부식측정 방법인 갈바닉 전류 측정과 마이크로 셀 부식측정 방법인 선형분극 측정법 및 교류 임피던스법을 이용하여 염화물 및 방청제의 영향을 평가하였다. 마크로/마이크로 셀 부식측정기 Calcium Nitrite 방청제가 첨가된 시험체의 경우 갈바닉 전류 측정결과 낮은 전류값을 유지하였고, 교류 임피던스 측정결과 분극저항의 감소가 나타나지 않았으므로, 방청제의 첨가가 콘크리트내 철근의 부동태 피막을 보호하여 부식저항성을 향상시킴을 알 수 있었다.

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