• Title, Summary, Keyword: Anodic polarization

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Influence of Ca-Si Addition on Anodic Polarization Chgaraqcteristics of Al-Zn-In Anodes (海水中 Al-Zn-In 合金陽極의 分極特性에 미치는 Ca-Si 添加의 影響)

  • Seo, Chang-Je
    • Journal of the Korean institute of surface engineering
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    • v.12 no.1
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    • pp.3-10
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    • 1979
  • Many excellent Al-Zn-In anode have been developed up to the present. But for the purpose of the better performance of Al-Zn-In anodes in sea water the effect of calcium silicon addition on anodic polarization and current capacity of Al-Zn-In anodes was measured and analysed in sea water and artificial sea water. The results and conclusions obtained are summarized as follows. 1) Being compared with Al-Zn-In anodes, Al-Zn-In anodes containing 0.05% calcium silicon had superior characteristics in both anodic polarization and current capacity. 2) Corrosion patterns of the anodes containing calcium silicon were much more uniform than those of Al-Zn-In anodes. 3) In this experiment the most useful anode was Al-4% Zn-0.03% In-0.05% (Ca-Si). It had a capacity of 2.60Amp-hr of current/g and a voltage of 1.13(SCE reference) at anodic current density 1,000 4{\mu}A/cm^2$.

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Influence of Redox Potential Current Density on Polarization Curves with Polypropylene Polymer

  • Park, Chil-Nam;Kim, Myung-Sun
    • Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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    • v.4 no.4
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    • pp.255-261
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    • 2000
  • Experiments were carried out to measure the corrosion potential and current density variations in the polarization curves of polypropylene. In particular, the results were examined to identify those influences affecting the corrosion potential, such as temperature, pH, salt, and oxygen. The Tafel slope for the anodic dissolution was determined based on the polarization effect under various conditions. Furthermore, the optimum conditions for the most rapid transformation were establish based on a variety of conditions, including temperature, pH, corrosion rate, and resistance of corrosion potential. The second anodic current density peak and maximum passive current density were designated as the critical corrosion sensitivity(I(sub)r/I(sub)f). This I(sub)r/I(sub)f value was then used to measure the critical corrosion sensitivity of polypropylene. The potentiodynamic parameters of corrosion were obtained using a Tafel plot.

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Anodic Polarization Properties of Ti-Zr-Pd Based Alloys for Biomedical Applications (생체용 Ti-Zr-Pd계 합금의 양극분극특성)

  • Jung, Jong-Hyun
    • The Journal of Korean Academy of Dental Technology
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    • v.23 no.1
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    • pp.21-30
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    • 2001
  • For biomedical applications. Ti-X%Zr-Y%Pd(X: $10{\sim}20$, Y:0.2 or 0.4) based alloys not containing harmful Al and V were newly designed, and polarization curves for their alloys were measured at $37^{\circ}C$ in 5% HCl solution in order to understand effects of Zr on the corrosion. From the results of anodic polarization behavior, it was found that the corrosion resistance increased with increasing Zr content. The results show their potential to develope Ti-based alloys for biomedical materials. The Ti-20%Zr-0.2%Pd alloy shows excellent corrosion resistance and was superior to those of the Ti. Ti-6%Al-4%V ELI alloy, Co-30%Cr-6%Mo alloy and STS 316L stainless steel.

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Micro Electrochemical Machining using Anodic Polarization Curve (양극분극곡선을 미용한 미세 전해가공)

  • 최영수;강성일;전종업;박규열
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.999-1002
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    • 2002
  • In this research, the mechanism of micro-ECM was investigated with potentiodynamic method and the optimal condition for micro-ECM was selected by voltage-current-time curve with potentiostatic method. From the experimental result. it was confirmed that anodic voltage curve could be used very effectively for determining the optimal condition of micro-ECM, and the micro part which has extremely fine surface could be fabricated by use of micro-ECM with point electrode method.

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Characteristics on Corrosion Resistance of Medium High Carbon Low Alloy Steels using Plasma Nitriding Process (플라즈마 질화처리한 중, 고탄소저합금강의 내식성에 관한 연구)

  • 이병찬
    • Journal of the Korean Society of Marine Engineering
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    • v.22 no.5
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    • pp.702-711
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    • 1998
  • The characteristics of corrosion resistance for the surface of medium high carbon steels and low alloy steels utilizing as manufacturing the machinery structures and machining tools and treating by plasma/ion nitriding process have been studied in terms of electrochemical polarization behav-iors including corrosion potential(Ecorr) anodic polarization trends and polarization resistance(Rp) The seven base materials showed a clear passivation behavior for the polarization tests in the ASTM standard solution 1N ${H_2){SO_4}$ Although the treated surface by plasma nitriding for the seven test materials showed a significant increase in hardness the treatment gave a detri-mental effect in corrosion resistance. The various characteristics including corrosion potential polarization curves microstructures corrosion current polarization resistance among non-treat-ed nitriding and/or soft-nitriding treated specimens have been investigated and some of the mechanisms discussed.

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Effect of Stress on the Polarization Characteristic of Al-brass (Al-황동의 분극특성에 미치는 응력의 영향)

  • Lim, Uh-Joh;Jeong, Hae-Kyoo;Sim, Kyong-Tae
    • Journal of the Korean Society of Safety
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    • v.19 no.2
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    • pp.1-5
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    • 2004
  • Al-brass is the raw material of mnufacturing tubes for heat exchanger of vessel where seawater is used to coolant because it has high level of heat coductivity and excellent mechanical properties and high level of corrosion resistance due to cuprous oxide($Cu_2O$) layer against seawater. However, damage of Al-brass tubes for heat exchanger of vessel is reported that local corrosion such as stress corrosion cracking occurred by synergism effect between mechanical factor and corrosion environment. In this study, to investigate on the effect of stress on the polarization characteristics of Al-brass. At the stress of 0% and 95% yield strength by constant displacement tester, in 3.5% NaCl + 0.1% $NH_4OH$ solution, the polarization tests were carried out. And thus open circuit potential, corrosion current density, anodic polarization, cyclic polarization and dezincification behavior of Al-brass are investigated.

The Study on the Corrosion Characteristics of Al-Alloy Shell for Cooler (알루미늄합금 원통냉각기의 부식 특성에 관한 연구)

  • 임우조;김성진;윤병두
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.39 no.2
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    • pp.152-157
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    • 2003
  • Most Recently, with rapid development in marine industries such as marine structures and ship, there occurs much interest in the study of corrosion characteristics which play an important role in design of cooling water system like heat-exchanger. Especially, as operating environment of fresh cooling water system in vessels is acidified, this system is seriously corroded. In this study, to study on the corrosion characteristics of Al-alloy shell for cooler, the electrochemical polarization test of materials for the marine fresh water cooler such as Al-alloy, Cu and naval brass was carried out in fresh water. And thus the polarization resistance and anodic polarization behavior of Al-alloy, Cu and naval brass are investigated. Also, galvanic corrosion characteristics of Al-alloy coupled with Cu and naval brass is considered. The main results obtained are as follows ; (1) The current density of corrosion is high in order of Al-alloy > naval brass > Cu (2) As anodic potential increases, the corrosion resistance of naval brass is better than that of Cu. (3) The galvanic corrosion of Al-alloy coupled with Cu and naval brass is activated than corrosion of Al-alloy.

A STUDY ON THE ANODIC POLARIZATION OF DENTAL AMALGAMS (수종 아말감의 Anodic Polarization에 관한 연구)

  • Um, Chung-Moon
    • Restorative Dentistry and Endodontics
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    • v.14 no.1
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    • pp.199-204
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    • 1989
  • The purpose of this study was to observe the anodic polarization curve from 4 kinds of low copper amalgam (Fine cut alloy, Spheralloy, Aristalloy and Amalcap) and 4 kinds of high copper amalgam (Dispersalloy, Sybraloy Orosphere and Tytin) obtained by using the potentiostat. The specimen made as the direction of manufacturer was stored at room temperature for about 7 days. The standard surface preparation was routinely carried out. The 0.9% saline solution was used as electrolyte in pH 6.8-7.0 at $37^{\circ}C$. The open circuit potential was determined after 30 minutes' immersion of specimen. The scan rate was 1mV/sec and the surface area of amalgam exposed to the solution was 0.785$cm^2$ for each specimen. All potentials reported are with respect to Ag/AgCl eelctrode. The following results were obtained. 1. The corrosion potential of high copper amalgams was higher than one of low copper amalgams, and the current density of high copper amalgam was lower than one of low copper amalgams. 2. The low copper amalgams had the similar pattern of polarization curve, but the high copper amalgams had the different pattern one another. 3. The polarization curve of Orosphere amalgam which is the admixed type was similar to one of low copper amalgam.

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정전위법에 의한 Alloy 600의 입계응력부식균열 거동 연구

  • 맹완영;강영환;일본명
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.111-116
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    • 1996
  • IGSCC(Intergranular stress corrosion cracking) behaviors of Alloy 600 were studied by the electrchemical ten methods of controlling specimens electrode potentials in the active-passive transition region of anodic polarization curve. Anodic polarization and static potential tests of stressed C-ring type MA Alloy 600 were carried out in 10% NaOH at 300 $^{\circ}C$ for 7days. It was confirmed that IGSCC of Alloy 600 was accellerated by maintaining the specimen potential in the susceptible active-passive transition region of anodic polarization curve. An intergranular crack was initiated on the surface area of C-ring specimens where protective oxide layer was broken down. And the depth of the crack growth was about 100 ${\mu}$m during the testing periods.

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Determination of optimum protection potential for cathodic protection of offshore wind-turbine-tower steel substructure by using potentiostatic method (정전위법에 의한 해상풍력 타워 구조물용 강재의 음극방식을 위한 최적방식전위 결정)

  • Lee, Jung-Hyung;Jung, Kwang-hu;Park, Jae-Cheul;Kim, Seong-Jong
    • Journal of the Korean Society of Marine Engineering
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    • v.41 no.3
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    • pp.230-237
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    • 2017
  • In this study, electrochemical methods were used to determine the optimum protection potential of S355ML steel for the cathodic protection of offshore wind-turbine-tower substructures. The results of potentiodynamic polarization experiments indicated that the anodic polarization curve did not represent a passivation behavior, while under the cathodic polarization concentration, polarization was observed due to the reduction of dissolved oxygen, followed by activation polarization by hydrogen evolution as the potential shifted towards the active direction. The concentration polarization region was found to be located between approximately -0.72 V and -1.0 V, and this potential range is considered to be the potential range for cathodic protection using the impressed current cathodic protection method. The results of the potentiostatic experiments at various potentials revealed that varying current density tended to become stable with time. Surface characterization after the potentiostatic experiment for 1200 s, by using a scanning electron microscope and a 3D analysis microscope confirmed that corrosion damage occurred as a result of anodic dissolution under an anodic polarization potential range of 0 to -0.50 V, which corresponds to anodic polarization. Under potentials corresponding to cathodic polarization, however, a relatively intact surface was observed with the formation of calcareous deposits. As a result, the potential range between -0.8 V and -1.0 V, which corresponds to the concentration polarization region, was determined to be the optimum potential region for impressed current cathodic protection of S355ML steel.