• 대한치과기공학회지
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• 제38권2호
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• pp.79-84
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• 2016

Purpose: The aim of this study was to make nanomesh on the surface of titanium by potentiostatic technique which was done at the suitable potential level. Methods: In order to find the suitable potential level, use a $25^{\circ}C$ NaCl, NaOH and NH4F solution of 1 M and 5 M as supporting electrolyte, working electrode(positive potential) was contact to the titanium specimen and counter electrode(negative potential) was contact to the Pt substrate. At the transpassive potential which was observed by potentiostatic technique, potentiostatic technique was done for 2hours. Results: As a result, 1 M NaOH solution was suitable as a supporting electrolyte, potentiostatic technique used a $25^{\circ}C$ NaOH solution of 1 M for 2hours, nanomesh was formed. Conclusion: The potentiostatic technique was used $25^{\circ}C$ NaOH solution of 1 M and 5 M as supporting electrolyte for 2hours. Nanomesh was built more uniform and fine in 1 M NaOH solution than 5 M NaOH solution.

• 한국표면공학회지
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• 제46권3호
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• pp.120-125
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• 2013

This investigation was to identify the electrochemical corrosion protection conditions to minimize the cavitation damage by generating hydrogen gas with the means of hydrogen overvoltage before the impact pressure of the cavity is transferred to the surface. The hybrid potentiostatic test method is designed to evaluate a complexed cavitation and electrochemical characteristic for ALBC3 alloy that is diverse and its broad applications fields in marine industry. The surface observation showed that neither the cavitation damage nor the electrochemical damage by the hydrogen gas generation occurred in the potential of -2.6 V under the cavitation environment. In the potentiostatic experiments under the cavitation environment, the cavities were reflected or cancelled out by the collision of the cavities with the hydrogen gas generated by the hydrogen overvoltage.

• 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.

• Corrosion Science and Technology
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• 제10권4호
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• pp.125-130
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• 2011

This study was performed to improve the corrosion resistance and the stability of passive film on copper tube by potentiostatic polarization method in synthetic tap water. Formation of passive film was carried out by anodic potentiostatic polarization at various passivation potentials and passivation times in 0.1 M NaOH solution. Stability of passive film and corrosion resistance was evaluated by self-activation time, ${\tau}_0$ from passive state to active state on open-circuit state in 0.1 M NaOH solution. Addition of polyphosphate in NaOH solution prolonged the self-activation time and improved the corrosion resistance, and the addition of 5 ppm polyphosphate was most effective. It was also observed that better corrosion resistance was obtained by potentiostatic polarization at 1.0 V (vs. SCE) than at any other passivation potentials. Passivated copper tube showed perfect corrosion resistance for the immersion test in synthetic tap water showing that the anodic potentiostatic polarization treatment in 0.1 M NaOH with 5 ppm polyphosphate solution would be effective in improving the corrosion resistance and preventing the blue water problem.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.56.1-56.1
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• 2010

A novel electrochemical potentiostatic method has been examined in order to enhance the hole concentration of p-type GaN thin films using KOH and HCl electrolyte. The hole concentration was increased more than 2 times by the electric voltge apply with the mobility of $10{\sim}12cm^2/V.s$. At optimum condition of 3V apply, hole concentration was enhanced more than reference sample from $1.7{\times}10^{-17}cm^{-3}$ to $4.1{\times}10^{-17}cm^{-3}$. Application of this activation method to blue-LED fabrication improved optical output from 18.4mW to 20.6mW, that is ~12% increase. SIMS analysis indicates that nearly 70% of hydrogen atoms could be removed by this method.

• 분석과학
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• 제6권2호
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• pp.157-165
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• 1993

강 중 석출물을 추출분리한 후 이를 정량분석하는 것을 목적으로 개발된 정전위 전해법을 304 스테인레스 판재 및 선재 제조시에 발생한 결함 원인 분석에 활용하여 시료의 조직을 관찰하였으며, 결함 원인을 조사하였다. 스테인레스 선재 및 판재의 균열 전파 양상은 정전위 전해법을 이용하여 에칭한 후 주사전자현미경으로 관찰하였고, 입계를 따라서 존재하는 조대한 석출물은 EDS 및 EPMA를 이용하여 성분분석을 행하였다. 이들 조대한 석출물의 구조분석은 X-선 회절 패턴을 이용하여 행하였다. 판재 및 선재 두 경우 모두 균열은 입계를 따라서 전파하고 있었으며, 입계에는 $M_{23}(C,\;B)_6$ 이외에 조대한 $M_2C$ 석출물이 존재하는 것으로 확인되었다. 이들 석출물들의 분석에 정전위 전해에칭법을 이용함으로써 양호한 시료를 얻을 수 있었다.

• 자원리싸이클링
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• 제10권4호
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• pp.18-23
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• 2001

페놀을 함유한 폐 활성탄의 가열 재생시 대기 오염물인 페놀이 생성되어 환경을 오염시키므로 발생하는 페놀 제거에 대한 검토가 필요하다 본 연구에서 실험에 사용하여 페놀을 함유한 S.회사 활성탄(WS-GAC), C.회사 활성탄(WC-GAC), L.회사 활성탄(UL-GAC)의 전해산화는 정전위 전해방식으로 실험하였다. 시료에 함유된 페놀농도는 100 rng/g, 지지 전해질은 1.0% 염화나트륨 용액, Ti-Ir(10$\times$10$ extrm{cm}^2$)전극 간격은 2 cm,전류밀도는 $1.25 A/dm^2$인 조건에서 실험이 이루워졌을 경우 전해 산화 실험에서 얻은 결과 페놀의 잔류물은 검출되지 않았다. 그러므로 전해산화 반응에서 빈응시간, 전류밀도, 지지전해질의 농도, 전극간의 거리가 60 minutes, 1.25 $A/dm^2$, 1.0%, 2 cm 임을 알 수 있었다.

• 전기화학회지
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• 제7권4호
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• pp.179-182
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• 2004

The aim of this study is to investigate the initiation and propagation of crevice corrosion for ferritic stainless steel in artificial crevice based on micro capillary tube method. The 430 stainless steel in artificial crevice is potentiostatically polarized in different sodium chloride solutions. Potentiodynamic and potentiostatic polarization data were measured in situ. The potentials in the crevice were measured by depth profile using the 0.04 mm diameter micro capillary tube inserted in the crevice. The potentials in the crevice ranged from -220 mV to -360 mV vs SCE from opening to bottom of crevice, which are lower than the external surface potential, -200 mV vs SCE. Such a potential drop induced the change of the metal surface state from passive to active. The surface of metal is located in passive state in -200 mV but the inner surface keeps active state below -220 mV, Thus these results show that the It drop mechanism in the crevice was more objective for evaluation and the method was easier to reproduce. Therefore the potential drop is one of the reasons for crevice corrosion by measuring the potentials in narrow crevice with a new micro measuring system.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 추계학술발표대회 요약집
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• pp.291.2-291.2
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• 2003

• 전기화학회지
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• 제1권1호
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• pp.8-13
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• 1998

This work presents the way how to evaluate the degree of reversibility of the discharging process undergone by the nickel hydroxide film cathodically deposited on pure nickel as a positive electrode for electrochemical capacitor using the combined cyclic voltammetry and potential drop method, supplemented by galvanostatic discharge and open-circuit potential transient methods. The time interval necessary just to establish the current reversal of anodic to cathodic direction from the moment just after applying the potential inversion of anodic to cathodic direction, was obtained on cyclic voltammogram. The cathodic charge density passed upon dropping the applied potential, was calculated on potentiostatic current density-time curve. Both the time interval and the cathodic charge density in magnitude can be regarded as being measures of the degree of reversibility of the discharging process undergone by the positive active material for supercapacitor, i.e. , the longer the time interval is, the lower is the degree of reversibility and the greater the cathodic charge density is, the higher is the degree of reversibility. From the applied potential dependences of the time interval and cathodic charge density, discharge at $0.42 V_{SCE}$ was determined to be the most reversible.