• 한국수소및신에너지학회논문집
• /
• 제9권4호
• /
• pp.169-176
• /
• 1998

Ni/MH 2차전지의 음극용 금속간화합물전극의 부식특성에 미치는 합금원소와 결합제의 영향을 조사하였다. 전극의 재료는 $(LM)Ni_{4.49}Co_{0.1}Mn_{0.205}Al_{0.205}$와 $(LM)Ni_{3.6}Co_{0.7}Mn_{0.3}Al_{0.4}$의 $AB_5$ type합금을 모재로 하였다. 여기에 Si sealant 또는 PTFE를 결합제로 첨가한 것과 원재료 분말에 구리를 20% 무전해도금한 것을 냉간 압착하여 전극을 제조하였다. 부식특성을 조사하기위해 탈공기된 6M의 KOH 용액에서 동전위법과 순환전위법을 이용하여 부식전류와 전류밀도를 측정하였다. 모재에 Co가 많이 함유되면 전극의 내식성을 향상시키고 Ni이 많이 함유되면 충전과 방전을 반복하는 동안에 전극의 안정성을 저하시켰다. 부식전류밀도는 Si sealant를 결합제로 사용한 전극의 경우가 PTFE를 사용한 전극의 경우보다 낮았고 Cu가 도금된 전극은 내식성에서 가장 우수하게 나타났다.

• 전기화학회지
• /
• 제7권2호
• /
• pp.94-99
• /
• 2004

연료극 지지체 평관형 고체산화물 연료전지(SOFC)의 셀 전력밀도를 증가시키기 위하여 압출법에 의하여 제조하고 그 특성을 연구하였다. 연료극 지지체로써 Ni/YSZ($8mol\%$ yttria stabilized zirconia) cermet는 기공율 $50.6\%,\;0.23{\mu}m$의 기공크기를 나타내었다. 지지체에서의 Ni의 분포는 균일하였으며 전자전도 경로로써의 Ni의 연결성은 양호하였다. 지지체에 YSZ전해질과 복합 공기극층인 $LSM((La_{0.85}Sr_{0.15})_{0.9}MnO_3)/YSZ$ 복합층, LSM, LSCF $(La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3)$층이 슬러리 디핑법에 의하여 코팅 및 소결된 연료극 지지체식 평관형 고체산화물 연료전지 단위전지의 성능은 $800^{\circ}C$에서 $300mW/cm^2(0.6V,\;500mA/cm^2)$의 성능을 나타내었다. 임피던스 분석에 의하여 평관형 셀의 전기화학적 분극저항을 평가하고 연료측의 가습에 따라 분극저항이 감소되어 성능이 향상됨을 알 수 있었다 슬러리 디핑법으로 LSM이 코팅된 SUS430 금속연결재를 $Ar+10\%\;H_2$에서 소결하였으며, $750^{\circ}C$에서 면저항의 측정할 결과, 초기에는 $148m{\Omega}cm^2$를 나타내었으며, 450시간 경과 후에 $43m{\Omega}cm^2$의 낮은 면저항을 유지하였다. 반면에 동일한 조건으로 LSM이 코팅된 Fecralloy는 높은 면저항을 나타내었다.

• 대한금속재료학회지
• /
• 제48권6호
• /
• pp.523-532
• /
• 2010

Co-application of organic coating and cathodic protection has not provided enough durability to low-alloyed steels inseawater ballast tank (SBT) environments. An attempt has made to study the effect of alloy elements (Al, Cr, Cu, Mo, Ni, Si, W) on general and localized corrosion resistance of steels as basic research to develop new low-allowed steels resistive to corrosion in SBT environments. For this study, we measured the corrosion rate by the weigh loss method after periodic immersion in synthetic seawater at $60^{\circ}C$, evaluated the localized corrosion resistance by an immersion test in concentrated chloride solution with the critical pH depending on the alloy element (Fe, Cr, Al, Ni), determined the permeability of chloride ion across the rust layer by measuring the membrane potential, and finally, we analyzed the rust layer by EPMA mapping and compared the result with the E-pH diagram calculated in the study. The immersion test of up to 55 days in the synthetic seawater showed that chromium, aluminium, and nickel are beneficial but the other elements are detrimental to corrosion resistance. Among the beneficial elements, chromium and aluminium effectively decreased the corrosion rate of the steels during the initial immersion, while nickel effectively decreased the corrosion rate in a longer than 30-day immersion. The low corrosion rate of Cr- or Al-alloyed steel in the initial period was due to the formation of $Cr_2FeO_4$ or $Al_2FeO_4$, respectively -the predicted oxide in the E-pH diagram- which is known as a more protective oxide than $Fe_3O_4$. The increased corrosion rate of Cr-alloyed steels with alonger than 30-day exposure was due to low localized corrosion resistance, which is explained bythe effect of the alloying element on a critical pH. In the meantime, the low corrosion rate of Ni-alloyed steel with a longer than 30-day exposure wasdue to an Ni enriched layer containing $Fe_2NiO_4$, the predicted oxide in the E-pH diagram. Finally, the measurement of the membrane potential depending on the alloying element showed that a lower permeability of chloride ion does not always result in higher corrosion resistance in seawater.

• Applied Science and Convergence Technology
• /
• 제24권5호
• /
• pp.162-166
• /
• 2015

Linear ion beams have been introduced for the ion beam treatments of flexible substrates in roll-to-roll web coating systems. Anode layer linear ion sources (300 mm width) were used to make the linear ion beams. Oxygen ion beams having an ion energy from 200 eV to 800 eV used for the adhesion improvement of Cu thin films on PET substrates. The Cu thin films deposited by a conventional magnetron sputtering on the oxygen ion beam treated PET substrates showed Class 5 adhesion defined by ASTM D3359-97 (tape test). Argon ion beams with 1~3 keV used for the ion beam sputtering deposition process, which aims to control the initial layer before the magnetron sputtering deposition. When the discharge power of the linear ion source is 1.2 kW, static deposition rate of Cu and Ni were 7.4 and $3.5{\AA}/sec$, respectively.

• 한국표면공학회지
• /
• 제37권2호
• /
• pp.76-79
• /
• 2004

Nickel chloride coated protein chip plate was developed by using a spin coating method. The ability of histidine tagged protein adsorption was investigated at various solvents. The surface of plate has a large aggregated nickel complex with high density in water. However, the surface of plate has a very small size of aggregated nickel complex with low density in isopropanol. The ability of protein adsorption decreased as increasing the size of alkyl chain in various alcohol solvents. The mechanism on the ability of protein adsorption at the plate surface is discussed.

• 한국분무공학회지
• /
• 제16권1호
• /
• pp.37-43
• /
• 2011

The present study conducted computational simulation for multiphase flow in the flame spray coating process with commercially available Ni-Cr powders. The flows in a flame spray gun is characterized by very complex phenomena including combustion, turbulent flows, and convective and radiative heat transfer. In this study, we used a commercial computational fluid dynamics (CFD) code of Fluent (ver. 6.3.26) to predict gas dynamics involving combustion, gas and particle temperature distributions, and multi-dimensional particle trajectories with the use of the discrete phase model (DPM). We also examined the effect of particle size on the flame spray process. It was found that particle velocity and gas temperature decreased rapidly in the radial direction, and they were substantially affected by the particle size.

• Carbon letters
• /
• 제9권2호
• /
• pp.105-107
• /
• 2008

In this work, we employed an electroless nickel plating on glass fibers in order to enhance the electric conductivity of fibers. And the effects of metal content and plating time on the conductivity of fibers were investigated. From the results, island-like metal clusters were found on the fiber surfaces in initial plating state, and perfect metallic layers were observed after 10 min of plating time. The thickness of metallic layers on fiber surfaces was proportion to plating time, and the electric conductivity showed similar trends. The nickel cluster sizes on fibers decreased with increasing plating time, indicating that surface energetics of the fibers could become more homogeneous and make well-packed metallic layers, resulting in the high conductivity of Ni/glass fibers.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.2205-2210
• /
• 2003

The 1st stage bucket of the 170MW simple cycle gas turbine is one of the components that is normally run in exposed state at the highest thermally stressful environment while the turbine is operating. After certain period operation, various type of damages are easily found and the damages are identified as due to the turbine operating mode of which the demand of the electricity power is very peaking and cyclic. Since this trend is more evident at some part of power plants in Korea and it has caused higher scrap rate of the bucket at the first repair interval than other country. Therefore, demand for the higher capability and alternative technologies which allow salvaging more buckets and preventing from severe damages is always high. In this study, a review and estimation of the repair technologies for the past 5 years to present have been conducted and show results.

• 태양에너지
• /
• 제9권2호
• /
• pp.69-77
• /
• 1989

The thermal degradation of electroplated black chrome coating on Ni substrates has been investigated by using Auger electron spectroscopy technique. The sample was prepared by electroplating at $20^{\circ}C$ for 20 seconds with the current density at $0.4A/cm^2$. Its surface oxidation process was investigated with 1 hour annealed sample for a temperature range of $300-550^{\circ}C$. While its optical solar absorption was dominated by fine metallic Cr particles, thermal degradation was occurred primarily by oxidation of metallic Cr particles as increasing the annealing temperature.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.416-416
• /
• 2014

탄소나노튜브(CNTs)의 비강도는 철합금에 비해 30~50배 높으며, 알루미늄 밀도($2.7g/cm^3$)보다 낮은 $1.3{\sim}1.4g/cm^3$의 값을 갖는 고강도 고경량의 탄소소재이다. 이러한 CNT를 금속기지에 복합화 하면 비강도가 매우 우수하고 고경량화 소재의 제조가 가능하다. 하지만, CNT는 반데르발스(Van der waals) 힘에 의해 서로 뭉쳐서 존재하며, 젖음성이 나쁘기 때문에 금속과 부상 분리되는 단점이 있다. 따라서, 이러한 문제점을 보완하기 위하여 무전해 도금법, 전해도금법 등으로 Cu, Ni등을 코팅하여 문제점을 해결하려는 연구가 진행되어 왔지만, 복합소재를 제조하기 위해 필요한 CNT를 대량으로 코팅하기엔 적합하지 않다. 본 연구에서는 CNT표면에 Cu를 대량으로 형성시킬 수 있는 시멘테이션법을 이용하여, 공정조건에 따른 CNT/Cu의 석출되는 형상 및 성분의 변화를 조사하였다.