• Corrosion Science and Technology
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• 제17권6호
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• pp.257-264
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• 2018

Anti-graffiti coatings have become more important. These layers must guarantee excellent corrosion protection properties, and graffiti must be easily removable, without reducing protection and aesthetic properties. In this study, anti-graffiti and corrosion behavior of two anti-graffiti polyurethane powder coatings were studied. These layers were deposited on aluminum substrate, with two different surface finishes, smooth, and wrinkled. The action of four different removers are investigated. Graffiti were drawn on coatings by means of red acrylic spray paint. Methyl-ethyl-ketone (MEK) and a "commercial" remover were the most effective solvents, in terms of graffiti removal capability, producing limited change in aesthetical surface aspect for smooth finishing. The wrinkled surface was less resistant. Corrosion protection properties, after removal action and contact with the remover, were evaluate by electrochemical impedance spectroscopy. After approximately 5 hours, coatings were no longer protective due to formation of defects. To simulate the weathering effect, UV-B cyclic test (4 hours of UV exposure followed by 4 hours of saturated humidity at $50^{\circ}C$) were performed for 2000 hours. Gloss and color changes were measured, and electrochemical impedance spectroscopy measurements were performed after aging and graffiti removal.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1873-1875
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• 1999

The effects of electrode and matrix in the PAFC were investigated using AC-impedance spectroscopy. The performance of PAFC was determined by changing external electronic load. AC impedance measurement was carried out as functions of phosphoric acid impregnation temperature. operating temperature and matrix coating method using various cathodes ; 20%Pt/C, 20%Pt-Ni/C, 20%Pt-Co-Ni/C, 10%Pt-Fe-Co/C, and 20%Pt-Fe-Co/C From the analysis of measured impedance data, the interfacial resistance decreased with increasing operating temperature. and with decreasing impregnation temperature. As compared with the alloy catalysts, Pt catalyst showed a lower interfacial resistance. This consist with the cell performance.

• 전기화학회지
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• 제2권4호
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• pp.195-201
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• 1999

탈기된 0.1 M $Na_2SO_4$ 수용액에서 Fe-Cr강의 재부동태 특성을 Cr함량, 인가전위 그리고 염소이온의 농도를 변화시키면서 관찰하였다. 염소이온이 없는 경우 재부동태 속도를 나타내는 식 log i=k-n log t에서 -n값은 Cr함량에 관계없이 -1에 수렴하였으나 Cr함량이 증가할수록 재부동태 전류밀도는 낮아졌다. A. C. impedance spectroscopy측정 결과, Cr 함량과 인가전위가 증가할수록 형성된 재부동태 피막의 charge transfer resistance$(R_{ct})$ 값은 상승하였다. 또한 재부동태 동안 흐르는 전류밀도를 Faraday식을 이용하여 피막의 두께를 계산해보면 Cr함량이 증가할수록 얇은 부동태 피막이 형성된다는 것을 알 수 있었다. 그러나 염소이온이 존재하는 경우, 염소이온이 Fe-Cr강의 재부동태를 방해하는 효과는 인가전위가 증가할수록 상승하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.320-321
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• 2006

In this work, impedance Spectroscopic analysis was applied to study the effect of plasma treatment on the surface of indium-tin oxide (ITO) anodes using $CF_4g$ as and to model the equivalent circuit for organic light emitting diodes (OLEDs) with the $CF_4$ plasma treatment of ITO surface at the anodes. This device with ITO/TPD/$Alq_3$/LiF/Al structure can be modeled as a simple combination of a resistor and a capacitor. The $CF_4$ plasma treatment on the surface of ITO shifts the vacuum level of the ITO as a result of which the barrier height for hole injection at the ITO/organic interface is reduced. The Impedance spectroscopy measurement of the devices with the $CF_4$ plasma treatment on the surface of ITO anodes shows change of values in parallel resistance ($R_p$) and parallel capacitance ($C_p$).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.436-437
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• 2006

In this work, impedance Spectroscopic analysis was applied to study the effect of plasma treatment on the surface of indum-tin oxide (ITO) anodes using $O_2$ gas and to model the equivalent circuit for organic light emitting diodes (OLEDs) with the $O_2$ plasma treatment of ITO surface at the anodes. This device with ITO/TPD/Alq3/LiF/Al structure can be modeled as a simple combination of a resistor and a capacitor. The $O_2$ plasma treatment on the surface of ITO shifts the vacuum level of the ITO as a result of which the barrier height for hole injection at the ITO/organic interface is reduced. The impedance spectroscopy measurement of the devices with the $O_2$ plasma treatment on the surface of ITO anodes shows change of values in parallel resistance ($R_p$) and parallel capacitance ($C_p$).

• 한국세라믹학회지
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• 제32권2호
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• pp.189-196
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• 1995

Materials retaining electrolyte of a phosphoric acid fuel cell (PAFC) have been prepared with SiC powder to SiC whisker mixing ratios of 1:1, 1:2, 1:3, 1:4, 0:1 by a tape casting method. When 3wt% dispersant (sorbitan monooleate) is added to a matrix, the porosity of the matrix decreases a little while the bubble pressure and area of the matrix increase remarkably in comparison with no dispersant content. Effect of the electrolyte resistance and the polarization resistance on perfomance of a PAFC has been investigated using A.C. impedance spectroscopy. With the increase of whisker content, the electrolyte resistance decreases due to the increase of porosity and acid absorbancy, and the polarization resistance increases due to the increase of surface roughness. The polarization resistance affects current density predominantly at the higher potential than 0.7V becuase the polarization resistance is considrably larger than the electrolyte resistance. Both the electrolyte resistance and the polarization resistance affect current density near 0.7V of the fuel cell operating potential because they have similar values. The electrolyte resistance affects current density predominantly at the lower potential than the fuel cell operating potential because the electrolyte resistance is larger than the polarization resistance.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.52-57
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• 2008

In the present study, impedance characteristics for AgO-Zn cell at various State-of-Charge (SoC) has been studied. The impedance measurements of AgO-Zn cell at various SoC were made over the frequency range from 100kHz to 10mHz with an amplitude 5mV. The impedance parameters have been evaluated by the analysis of the data using an equivalent circuit and a Non-linear least squares (NLLS) fitting method. The total resistances reflects the SoC of the cell. This indicates that the total resistance is important parameter for predicting SoC of AgO-Zn cell.

• 한국세라믹학회지
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• 제45권12호
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• pp.788-795
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• 2008

An electrolyte supported SOFC cell was tested at $800^{\circ}C$ in air for 3600 h with an applied current density of $200\;mA/cm^2$ to examine possible cathode degradation issues. A scandium- stabilized zirconia (ScSZ) with additional manganese doping (ScSZ: Mn) was used as electrolyte. A strontium and copper-doped lanthanum ferrite (LaSrCuFe) and platinum were used as cathode and quasi-anode material, respectively. The DC resistance was logged over the complete testing period. Additionally, impedance spectroscopy was used from time to time to track changes of the cell in-situ. Post-test analysis of the cell using methods like scanning electron microscopy imaging and other electrochemical testing methods allow the identification of different degradation sources. The results indicate a promising combination of electrolyte and cathode material in terms of chemical compatibility and electrical performance.

• 한국세라믹학회지
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• 제39권6호
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• pp.540-549
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• 2002

본 실험에서는 Impedance Spectroscopy(IS)를 이용하여 플라이 애쉬, 고로 슬래그, 실리카 퓸 등의 혼합재가 치환 첨가된 포틀랜드 시멘트의 수화거동을 검토하였다. 플라이 애쉬 및 고로 슬래그가 시멘트에 치환 첨가될 경우, 수화 초기 IS 의 전기적 변수, $R_{t(s+1)}$과 $R_{t(s+1)}$의 증가폭이 감소하였다. 이것은 동일한 W/C비에서 혼합재를 포함한 시멘트의 수화가 늦게 진행되고 있음을 보여준다. 그러나, 실리카 퓸의 경우 초기에 매우 빠른 포졸란 반응성으로 인하여 플라이 애쉬 및 고로 슬래그가 첨가된 경우에 비해 큰 폭의 $R_{t(s+1)}$ 및 $R_{t(s+1)}$ 변화를 확인 할 수 있었다. OPC-플라이 애쉬계의 경우 반원과 직선 영역 사이에서 특이 할만한 평할한 곡선 영역이 출현하였으며, 수화가 진행되고 플라이 애쉬의 치환첨가량이 증가할수록 그 영역이 증가하였다.

• 한국전기전자재료학회논문지
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• 제24권11호
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• pp.876-881
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• 2011

The sintering, defect and grain boundary characteristics of Bi-based ZnO chip varistor (1,608 mm size) have been investigated to know the possibility of lowering a manufacturing price by using 100 % Ag inner-electrode. The samples were prepared by general multilayer chip varistor process and characterized by shrinkage, SEM, current-voltage (I-V), admittance spectroscopy (AS), impedance and modulus spectroscopy (IS & MS) measurement. There are no problems to make a chip varistor with 100% Ag inner-electrode in the sintering temperature range of 850~900$^{\circ}C$ for 1 h in air. A good varistor characteristics ($V_n$= 9.3~15.4 V, a= 23~24, $I_L$= 1.0~1.6 ${\mu}A$) were revealed but formed $Zn_i^{{\cdot}{\cdot}}$(0.209 eV) as dominant defect, and increased the distributional inhomogeneity and the temperature instability in grain boundary barriers.