• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.245-248
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• 2005

It should be noted that the critical chloride threshold level is not considered to be a unique value for all conditions. This value is dependent on concrete mixture proportions, cement type and constituents, presence of admixtures, environmental factors, steel reinforcement surface. conditions, and other factors. In this study, the accelerated corrosion test for reinforcing steel was conducted by electrochemical and cyclic wet and dry seawater method, respectively and during the test, corrosion monitoring by half cell potential method was carried out to estimate the chloride corrosion threshold value when corrosion for reinforcing steel in concrete was perceived. For this purpose, lollypop and right hexahedron test specimens were made for 31.4$\%$, 41.5$\%$ and 49.7$\%$ of w/c, respectively and then the accelerated corrosion test for reinforcing steel was executed. It was observed from the test that the time to initiation of corrosion was found to be different with water-cement ratio and accelerated corrosion test method, respectively and the chloride corrosion threshold value was found to range from 0.91 to 1.43 kg/$m^{3}$.

• 기술표준
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• 통권14호
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• pp.85-98
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• 2003

• 방사성폐기물학회지
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• 제8권3호
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• pp.247-260
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• 2010

한국원자력연구원 처분시스템개발과제에서는 처분용기 재료로 개발중인 저온분사코팅 구리에 대한 틈새부식(Crevice Corrosion) 시험을 실시하였다. 본 시험을 통하여 틈새에서의 부식의 발생여부와 발생되는 시점인 재부동태 전위(Repassivation Potential)를 측정하고자 하였다. 틈새부식 시험 방법으로 (1) ASTM G61-86 : Cyclic Potentiodynamic Polarization Measurements, (2) SWRI의 Potentiodynamic Polarization plus intermediate Potentiostatic Hold method, 그리고 (3) ASTM G192-08 (THE method) :Potentiodynamic- Galvanostatic -Potentiostatic Method 등의 3가지 방법을 소개하였다. 실제 저온분사 코팅구리의 부식시험에서는 ASTM G61-86에 따라서 틈새부식장치를 설치하고, 저온분사코팅구리가 KURT 지하수를 모사한 용액에서 어떻게 틈새부식이 일어나는지 살펴보았다. 전기적 부식조건으로는 Cyclic Polarization Test, Potentiostatic Polarization Test, 및 Electrochemical Impedance Spectroscopy 등을 사용하였다. 그리고 부식이 된 시편에 대해 Profilometer Measurement를 통해 실제 부식표면의 높낮이를 조사하여 틈새부식 유무를 관찰하였다. 최종적인 결론에서는 저온분사코팅구리는 틈새부식을 나타나지 않는다는 것을 확인할 수 있었다. 그리고 시험에 사용된 세종류의 구리에 대한 상대적인 부식평가를 한 결과, 부식전위를 나타내는 개방회로(Open Cell)에서의 전위는 구리의 제조방식과 상관없이 구리의 순도가 높을수록 높은 값을 보이는 것을 확인할 수 있었다. 결론적으로 KURT 심층지하수 조건에서는 구리는 틈새부식이 발생되지 않는다고 결론지었다.

• 동력기계공학회지
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• 제11권3호
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• pp.41-46
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• 2007

The microstructure and electrochemical analysis of welds of electric resistance welding(ERW) pipe were investigated. The direction of metal flow line in HAZ of ERW pipe shifted to the inner(or outer) surface of pipe by plastic deformation during welding. The lowest heat input welds of ERW pipe was showed crack by liquid penetrant testing. Accelerated corrosion test by constant current density of 20mA/$cm^{2}$ developed groove at the welds of ERW pipe and the measured grooving factors were about $1.2{\sim}1.5$. Corrosion potential of base metal obtained by cyclic polarization in artificial sea water(3.5wt.% NaCl solution) was 100mV higher than that of weld metal of ERW pipe.

• 한국표면공학회지
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• 제20권3호
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• pp.95-105
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• 1987

For the purpose of improving the hot corrosion resistance of Ni-base superalloy, Inconel 600, aluminide and chromium-aluminide coatings by pack cementation process were studied. The morphology of these coatings is dependent on the type of process employed. And their overall composition depends on the composition of the base alloy and on the nature of the cement. Therefore the different aluminide and chromium-aluminide coatings obtained on a superalloy do not possess the same resistance to oxidation and hot corrosion. The mechanisms governing the formation of the coatings and the composition of the coating were varied by pack composition and temperature, and cyclic hot corrosion resistance of the auluminide coating formed by one-step process was inferior to that of the coating formed by two-step process. and Cr-Al composite coating showed good resistance for cyclic hot corrosion.

• Corrosion Science and Technology
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• 제3권6호
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• pp.251-256
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• 2004

Exposure of zinc samples in simulated acid rain solution (SARS) was investigated under a periodic wet-dry conditions using an AC impedance technique. The periodic wet and dry exposure consisted of the immersion of zinc samples in SARS for one hour followed by exposure to 7 hours drying at 60% RH. Phases of the corrosion products were indentified by X-ray diffraction (XRD). The influence of relative humdiity (RH), temperature, and surface inclination on the atmospheric corrosion of zinc is described. The reciprocal of polarization resistance (1/Rp) decreases rapidly during the initial stages then slowly and eventually attains a steady state as exposure time progresses. The average of reciprocal of polarization resistance per cycle, (ARPR) was calculated and found to decrease as number of exposure cycle increases. An increase of temperature enhances the corrsion rate of zinc. The values of ARPR, of a sample inclined at 30 o are lower than those for a sample oriented horizontally. The experiment result shows a pronounced dependence of reciprocal of polarization resistance on RH. Exposure in the presence of carbonate anions gives rise to more protective corrosion products than in nitrate anion solution. The corrosion mechanism during the initial stages of atmospheric zinc corrosion under wet-dry cyclic conditions is suggested.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.192-193
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• 2005

Magnesium thin films were prepared on cold-rolled steel substrates by RF(Radio Frequency) magnetron sputtering technique.$^{1)}$ The crystal orientation and monitoring of the deposited films were investigated by using XRD(X-ray Diffraction) and EIS(Electrochemical Impedance Spectroscopy), respectively. The corrosion rates of Mg thin films deposited with different argon gas pressure and substrate bias voltage were monitored by AC impedance method under a cyclic wet-dry condition, which was conducted by exposure to alternate conditions of 1h immersion in 3%NaCl solution and 5h drying at 60% RH and 25$^{\circ}C$. The result of corrosion rate of Mg thin films deposited at various Ar gas pressures and substrate bias voltage under wet-dry cyclic exposure in chloride-containing solutions was showed the following conclusions. At the region I during the onset of the wet cycle, corrosion rate showed relatively low value. The increase in the Corrosion rate of region II is due to the increase in the chloride concentration. Corrosion rate of region III during the onset of the cycle zero and salt crystals remain on the metal surface.$^{2)}$

• 한국응용과학기술학회지
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• 제29권1호
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• pp.88-94
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• 2012

순환전압전류법을 사용하여 전류-전압 곡선을 측정하였다. 전기화학적 특성과 금속의 표면상태간의 관계는 전자현미경(SEM)을 사용하여 조사하였다. 그리고 순환전압전류법에 의한 전기화학적 측정은 3 전극 시스템을 사용하였다. 측정 범위는 초기 포텐셜에서 -1350 mV까지 환원시키고, 연속적으로 1650 mV까지 산화시키고, 다시 초기지점으로 환원시켜 측정하였다. 스캔속도는 50, 100, 150, 200 및 250 mV/s를 선정하였다. 그 결과, 부식억제로 모노에탄올아민(MEA)을 사용하여 금속의 C-V 특성은 순환전압전류법으로부터 산화 전류에 기인한 비가역 공정으로 나타났다. 부식억제제로 MEA을 사용하였을 경우에는 전해질의 농도가 증가할수록 확산계수가 감소하는 경향을 나타내었다. 그리고 구리의 SEM 이미지를 보면, 전해질 농도를 증가시키면 표면부식은 증가하였다. 부식억제제로 $1.0{\times}10^{-3}M$ MEA를 첨가시키면, 전해질 농도 0.1 N의 경우 확산계수가 상대적으로 커서 부식억제 효과가 적었다.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.90-98
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• 2002

In this paper, the annealing heat treatments for the best corrosion resistant of Ti(Grade 2) were studied in a 3.5% NaCl solution by electrochemical methods. The annealing heat treatments were accomplished at 650, 700 and $750^{\circ}C$ with different time of 30min., 1hour and 2 hours in a vacuum condition. The obtained results are: 1) in the case of solution heat treated $930^{\circ}C$ for 2 hours in a vacuum and air, the corrosion potentials were -348.7 and -567. 1mV, and current densities 2.32 and $22.62\mu\textrm{A}$, respectively, 2) as increase both annealing heat treatment temperature 650, 700, $750^{\circ}C$ and time 30min., 1 hour, 2 hours, the corrosion potential were decreased, whereas corrosion current density increased, 3) in the case of cyclic polarization, the measured charges were increased as increasing solution heat treatment temperature and time, 4) on the bases of corrosion potential, current density and charge, the best annealing temperature and time were measured as $700^{\circ}C$ and 30min. for Ti(Grade 2) material.

• 한국응용과학기술학회지
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• 제27권3호
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• pp.361-369
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• 2010

A study on the corrosion inhibition of metals is important in many industrial applications (carbon steel, copper, aluminum, SUS 304, nickel). In this study, we investigated the C-V diagrams related to the surface corrosion of metals. It was observed through the SEM that the surface corrosion state of the various metals had the corrosion potential by the scan rate and the organic inhibitor containing an amine group. We determined to measure cyclic voltammetry using the three-electrode system. The measurement of oxidation and reduction ranged from -1350mV to 1650mV. The scan rate was 50, 100, 150, and 200mV/s. It turned out that the C-V characterization of SUS 304 was irreversible process caused by the oxidation current from the cyclic voltammogram. After adding organic inhibitors, the adsorption film was constituted, and the passive phenomena happened. As a result, it was revealed that the inhibition effect of metal corrosion depends on the molecular interaction, and the interaction has influence on the adsorption complex.