• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.11.1-11.1
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• 2010

As one of the non-vacuum, low temperature fabrication route, electrochemical synthesis has been focused for pursuing the cost-effective pathway to produce high efficiency photovoltaic devices. Especially the availability to form the thin film structure on flexible substrate would be the great advantage of electrochemical process. The successful synthesis of the most favorable absorber materials such as CdTe and CIGS has been reported by many researchers, however, the efficiency of electrochemically synthesized could not exceed that from vacuum process, because of microstructural controllability and compositional variation on devices. In this study, we represent the effect of process parameters on the microstructure and composition of compound semiconductor during the synthesis, and propose the photovoltaic characteristics of electrochemically synthesized solar cells.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.449-453
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• 2005

Electrochemical systems find widespread technical application. Industrial electrolytic process include electroplating, electroforming, and electropolishing. Electroforming and electroplating is widely used in the manufacture of metal parts. This paper based on the basic equations of electrics and electrochemical kinetics, was employed for a theoretical explanation of the current density distribution on electroforming process. We calculated current density distribution and potential distribution on cathode. Also, calculated current density distribution of vertical direction. It was shown that current density is related with distance of between anode and cathode and mass transfer process. And make an experiment on its relation and electroformed thickness. It shows that it is useful method using FEM with multi-physics to estimate electroformed thickness.

• 한국표면공학회지
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• 제55권3호
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• pp.143-155
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• 2022

Ceramic oxide layers successfully were formed on the surface of cast Al alloys with high Si contents using plasma electrolytic oxidation (PEO) process in electrolytes containing Na₂SiO₃, NaOH, and additives. The microstructure of the oxide layers was systematically analyzed using scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (TEM), X-ray diffraction patterns (XRD), and energy X-ray dispersive spectroscopy (EDS). XRD analysis indicated that the PEO untreated high-silicon Al alloys (i.e., 17.1 and 11.7 wt.% Si) consist of Al, Si and Al₂Cu phases whereas Al₂Cu phase selectively disappeared after PEO treatment. PEO process yielded an amorphous oxide layer with few second phases including γ-Al₂O₃ and Fe-rich phases. The corrosion behaviors of high-silicon Al alloys treated by PEO process were investigated using electrochemical impedance spectroscopy (EIS) and other electrochemical techniques (i.e., open circuit potential and polarization curve). Electroanalytical studies indicated that high-silicon Al alloys treated by PEO process have greater corrosion resistance than high-silicon alloys untreated by PEO process.

• 마이크로전자및패키징학회지
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• 제18권1호
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• pp.23-27
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• 2011

전기화학적 에칭을 이용한 다공성 실리콘 이중층 형성은 초박형 태양전지 제작에서 PS layer transfer 기술을 적용하기 위한 선행 공정이다. 다공성 실리콘 층의 다공도는 전류밀도와 에칭용액 내 불산의 농도를 조절하여 제어할 수 있다. 전기화학적 에칭을 이용한 다공성 실리콘 형성을 위하여 비저항 $0.01-0.02\;{\Omega}{\cdot}cm$의 p-type (100)의 실리콘 웨이퍼를 사용하였으며, 에칭용액의 조성은 HF (40%) : $C_2H_5OH$(99 %) : $H_2O$ = 1 : 1 : 2 (volume)으로 고정하였다. PS layer transfer 기술에 사용되는 다공성 실리콘 이중층을 형성하기 위해서 에칭 도중 전류밀도를 낮은 전류밀도 조건에서 높은 전류밀도 조건으로 변환하여 low porosity layer 하부에 high porosity layer를 형성할 수 있다.

• 한국해양환경ㆍ에너지학회지
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• 제6권3호
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• pp.45-53
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• 2003

본 연구에서는 선저폐수 중에 유화된 상태의 유분이 존재할 경우엔 기존의 유처리 분리장치에 의해 선박의 배출허용기준치를 만족하는데 어려움이 있는 것을 감안하여 기존의 유처리 분리시스템에 전기화학적 처리장치를 추가하는 방안을 검토하고자한다. 이를 위해 실험실 규모의 전기화학적 처리장치를 설계ㆍ제작하여 각종 변수인 수력학적 체류시간, 전류밀도, 양극과 음극간의 간격 등을 변화시키며 유화유 폐수중의 유분 제거성능실험을 실시하였으며, 유화된 선저폐수 중의 유분 제거성능실험을 수행하였다. 본 실험결과 전기화학적 처리장치에 의해 유화유 폐수를 효과적으로 처리할 수 있는 가능성을 확인할 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제13권2호
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• pp.261-268
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• 2022

In this study, electrochemical treatment of urban wastewater with electrical conductivity of 1000 μS cm^-1 and chemical oxygen demand of 250 mg L^-1 was investigated using the variables of initial pH value, current density and flow rate. Electrocoagulation was used, in which aluminum and stainless steel were selected, as the electrochemical treatment process. The electrocoagulation process was operated in continuous mode. The data obtained in experimental studies show that the best COD removal efficiency occurred in experiments where the initial pH value was 6. The increase in current density from 5 A to 15 A decreased the removal efficiency from 79 to 67%. The increase in flow rate under constant current density also reduced the efficiency of removal as expected. In experiments in which current density and flow rate were examined together, the increase in flow rate allowed the application of higher current densities. This situation led to considerable reductions in energy consumption values, even if the COD removal efficiency did not significantly increase. The high COD removal obtained with the use of high flow rate and high current density indicates that the electrocoagulation process can be used for high flow rate municipal wastewater treatment.

• 대한환경공학회지
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• 제31권8호
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• pp.627-634
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• 2009

본 연구는 염화 이온 ($Cl^-$)을 전해질로 이용하는 전기화학적 공정에서 생성되는 염소산화부산물인 클로레이트 ($ClO_3\;^-$, 염소산염)의 생성 메커니즘을 알아보기 위해 수행되었다. 우선, pH 및 초기농도에 따른 생성 특성을 살펴보았으며, 유리염소 생성과의 관련성 및 오존, OH 라디칼 등의 혼합산화제의 영향을 간접 평가하여 클로레이트의 생성 메커니즘을 구체화하였다. 그 결과, 클로레이트의 생성은 유리염소 (HOCl/$OCl^-$)의 전기화학적 반응을 주된 반응으로 하며, 염화 이온의 직접 양극산화 반응 및 OH 라디칼에 의한 경로가 있음을 확인하였다. 이어서 생성된 클로레이트가 퍼클로레이트로 산화되는 반응도 볼 수 있었다. 또한, 전극 간격에 따른 생성 농도를 유리염소 생성과 함께 평가하여, 유리염소 생성 효율은 극대화 시키되 클로레이트의 발생을 최소화 할 수 있는 최적조건을 찾는 방안을 제시하였다.

• 전기화학회지
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• 제2권2호
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• pp.106-111
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• 1999

[ $CaNi_5$ ] 수소저장합금의 전기화학적 충$\cdot$방전 특성에 미치는 MG(mechanical grinding) 영향이 Ar및 $H_2$ 가스분위기에서 조사되었다 MG공정중 $CaNi_5$ 합금은 표면 산화층의 파괴와 재생성 및 산화층 근방의 불균질화로 인하여 MG 15시간 이후부터 CaO와 Ni로 뚜렷한 상분리가 일어났다. $MG-CaNi_5$는 MG시간이 길어질수록 초기의 전기화학적 방전용량은 현저히 감소하였지만 충$\cdot$방전 싸이클의 증가에 따른 용량저하 속도는 $CaNi_5$합금에 비하여 낮았다. MG처리된 $CaNi_5$합금의 퇴화는 MG공정중의 상분리 및 불규칙화에 의한 수소의 가역반응 site의 감소 및 분극저항의 증가, KOH 전해질 내에서 합금 표면의 산화반응에 의한 부동태 피막형성에 기인하는 것으로 판단되었다.

• Tribology and Lubricants
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• 제31권3호
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• pp.79-85
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• 2015

RC delay is a critical issue for achieving high performance of ULSI devices. In order to minimize the RC delay time, we uses the CMP process to introduce high-conductivity Cu and low-k materials on the damascene. The low-k materials are generally soft and fragile, resulting in structure collapse during the conventional high-pressure CMP process. One troubleshooting method is electrochemical mechanical polishing (ECMP) which has the advantages of high removal rate, and low polishing pressure, resulting in a well-polished surface because of high removal rate, low polishing pressure, and well-polished surface, due to the electrochemical acceleration of the copper dissolution. This study analyzes an electrochemical state (active, passive, transpassive state) on a potentiodynamic curve using a three-electrode cell consisting of a working electrode (WE), counter electrode (CE), and reference electrode (RE) in a potentiostat to verify an electrochemical removal mechanism. This study also tries to find optimum conditions for ECMP through experimentation. Furthermore, during the low-pressure ECMP process, we investigate the effect of current density on surface roughness and removal rate through anodic oxidation, dissolution, and reaction with a chelating agent. In addition, according to the Faraday’s law, as the current density increases, the amount of oxidized and dissolved copper increases. Finally, we confirm that the surface roughness improves with polishing time, and the current decreases in this process.

• Corrosion Science and Technology
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• 제17권1호
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• pp.20-29
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• 2018

Ti and its alloys show the excellent corrosion resistance to chloride environments, but they show less corrosion resistance in HCl, $H_2SO_4$, NaOH, $H_3PO_4$, and especially HF environments at high temperature and concentration. In this study, we used the commercially pure titanium and Ti-6Al-4V alloy, and evaluated the effect of the manufacturing process on the electrochemical properties. We used commercial products of rolled and forged materials, and made additive manufactured materials by DMT (Directed Metal Tooling) method. We annealed each specimen at $760^{\circ}C$ for one hour and then air cooled. We performed anodic polarization test, AC impedance measurement, and Mott-Schottky plot to evaluate the electrochemical properties. Despite of the difference of its microstructure of CP-Ti and Ti-6Al-4V alloys by the manufacturing process, the anodic polarization behavior was similar in 20% sulfuric acid. However, the addition of 0.1% hydrofluoric acid degraded the electrochemical properties. Among three kinds of the manufacturing process, the electrochemical properties of additive manufactured CP-Ti, and Ti-6Al-4V alloys were the lowest. It is noted that the test materials showed a Warburg impedance in HF acid environments.