• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3201-3204
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• 2000

In general, analog tester or strip chart recorder have been used to measure the corrosion potential of structures such as gas pipelines, oil pipelines, hot water pipelines, power cables etc. Recently, automatic digital data logger substitutes for these manual equipment because using these manual equipments are tedious and time consuming. However, digital data logger also has a shortcoming, that is, short measuring time because of the short lifetime of batteries. Therefore, we developed a long lifetime and low power loss battery taking advantage of galvanic series. In this paper, the results of development for power generator using two metals and DC/DC converter in order to obtain enough voltage for the operation of digital data logger. DC/DC converter operates with 0.5[V]. Its output voltage is 3.5[V] and output current is from 60[mAh] to 1,200[mAh].

• Corrosion Science and Technology
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• 제12권1호
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• pp.12-26
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• 2013

This work focused on galvanic corrosion of carbon steel bolted GECM/Al plates by long-term test in tap water and NaCl solutions. Test product was carbon steel bolted between cross packed GECM and painted aluminium. Tests for the product and coupled parts determined corrosion rate in tap water and NaCl solutions. Also, using a potentiostat and salt water sprayer, galvanic test was done. In galvanic test on carbon steel bolted GECM/Al plates, corrosion of carbon steel bolt was faster in series of tap water>1% NaCl solution>3.5% NaCl solution. In galvanic couple between aluminium and carbon steel bolt, their corrosion rates were higher than those of single specimen. In galvanic couple between GECM, aluminium, and carbon steel bolt, corrosion behaviors of carbon steel bolt and aluminium were changed due to different corrosion mechanism in tap water and chloride solution.

• Corrosion Science and Technology
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• 제19권2호
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• pp.75-81
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• 2020

To reduce structural weight, light metals, including aluminum and magnesium alloys, have been widely used in various industries such as aircraft, transportation and automobiles. Recently, composite materials such as Carbon Fiber Reinforced Plastics (CFRP) and Graphite Epoxy Composite Material (GECM) have also been applied. However, aluminum and its alloys suffer corrosion from various factors, which include aggressive ions, pH, solution temperature and galvanic contact by potential difference. Moreover, carbon fiber in CFRP and GECM is a very efficient cathode, and very noble in the galvanic series. Galvanic contact between carbon fiber composites and metals in electrolytes such as rain or seawater, is highly undesirable. Notwithstanding the potentially dangerous effects of chloride and temperature, there is little research on galvanic corrosion according to chloride concentration and temperature. This work focused on the effects of chloride concentration and solution temperature on AA7075T6. The increased galvanic corrosion between CRFP and AA7075T6 was evaluated by electrochemical experiments, and these effects were elucidated.

• Bulletin of the Korean Chemical Society
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• 제29권2호
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• pp.445-449
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• 2008

Micrometer-sized copper (mCu) powders are weakly surface-enhanced Raman scattering (SERS) active by the excitation at 632.8 nm, but nearly ineffective as a SERS substrate at 514.5 nm excitation. The SERS activity of mCu powders at both excitation wavelengths can be increased dramatically by a simple method of the galvanic exchange reaction with AgNO3 in aqueous medium. In this work, the SERS activity of the Ag-exchanged Cu powders (mCu@Ag) has been evaluated by taking a series of Raman spectra using benzenethiol (BT) as the probe molecule. It is clearly confirmed by field emission scanning electron microscopy and X-ray diffractometry that the SERS activity of mCu@Ag powders is, in fact, highly dependent on the extent of galvanic reaction.

• 한국철도학회논문집
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• 제4권2호
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• pp.62-70
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• 2001

Pure copper, Cu-1.1wt%Cd and ACSR(Aluminum Conductor Steel Reinforced) have been used as catenary materials of the electric railway system. Since these materials may be exposed to the corrosive environments like polluted air, acid rain and sea water, it is important to investigate the corrosion rates in various corrosive environments. The aqueous corrosion characteristics of catenary materials in aerated acid, neutral and alkali solutions were studied by using immersion corrosion tests, electrochemical measurements and analytical techniques. In order to examine corrosion characteristics according to the dissolved oxygen content, pH, chloride ion concentration ion, and the addition of Cd to Cu, a series of tests such as potentiodynamic polarization, a.c impedance spectroscopy and galvanic corrosion tests were carried out with these materials. Results showed that the addition of Cd to Cu and chloride ion in the solution have an adverse effects on the resistance to corrosion. Additionally, Galvanic currents between Al and steel wires of ACSR were confirmed by using ZRA(zero resistance ammeter) method.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.58-68
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• 2000

When SS400 steel was welded with low hydrogen type and ilmennite type welding, the effect of post-weld heat treatment(PWHT) was investigated with parameters such as micro vickers hardness, corrosion potential, polarization behaviors, galvanic current, Al anode generating current and Al anode weight loss etc. Hardness of each parts(HAZ, BM, WM) by PWHT in case of low hydrogen type and ilmennite type welding was lower than that of each parts by As-welded However hardness of WM area in case of low hydrogen type and ilmennite type welding was the highest among those three parts regardless of PWHT, Whereas in case of ilmennite type welding, WM area was the highest potential among these three parts on galvanic potential series with As-welded while BM area was the highest potential among these three parts by PWHT on the contrary. And in case of low hydrogen type welding, galvanic corrosion and micro cell corrosion of welding parts was decreased with PWHT. However, It was increased with PWHT in case of ilmennite type welding. Moreover Al anode generating current and anode weight loss in case of low hydrogen type was decreased by PWHT compared to As-wedled but, which was increased than that of As-welded in case of ilmennite type welding. Therefore, it is suggested that Corrosion resistance property in case of low hydrogen type welding is increased by PWHT. However its property was devreased with PWHT in case of ilmennite type welding.

• Steel and Composite Structures
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• 제42권4호
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• pp.553-568
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• 2022

This paper explored the viability of utilising titanium alloy bolts in the construction industry through an experimental programme, where a total of sixty-six titanium alloy (Ti/6Al/4V) bolts were tested under axial tension, pure shear and combined tension and shear. In addition, a series of Charpy V-notch specimens machined from titanium alloy bolts, conventional high-strength steel bolts, austenitic and duplex stainless steel bolts were tested for impact toughness comparisons. The obtained experimental results demonstrated that the axial tensile and pure shear capacities of titanium alloy bolts can be reasonably estimated by the current design standards for steel structures (Eurocode 3, AS 4100 and AISC 360). However, under the combined tension and shear loading conditions, significant underestimation by Eurocode 3 and unsafe predictions through AS 4100 and AISC 360 indicate that proper modifications are necessary to facilitate the safe and economic use of titanium alloy bolts. In addition, numerical models were developed to calibrate the fracture parameters of the tested titanium alloy bolts. Furthermore, a design-based selection process of titanium alloy bolts in the structural applications was proposed, in which the ultimate strength, ductility performance and corrosion resistance (including galvanic corrosion) of titanium alloy bolts was mainly considered.

• Journal of Power Electronics
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• 제16권2호
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• pp.786-797
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• 2016

This paper describes the design and development of a novel semiconductor-based solid-state switch for damped oscillating voltage test system. The proposed switch is configured as two identical series-connected switch stacks, each of which comprising 10 series-connected IGBT function units. Each unit consists of one IGBT, a gate driver, and an auxiliary voltage sharing circuit. A single switch stack can block 20 kV-rated high voltage, and two stacks in series are proven applicable to 30 kV-rated high voltage. The turn-on speed of the switch is approximately 250 ns. A flyback topology-based power supply system with a front-end power factor correction is built for the drive circuit by loosely inductively coupling each unit with a ferrite core to the primary side of a power generator to obtain the advantages of galvanic isolation and compact size. After the simulation, measurement, and estimation of the parasitic effect on the gate driver, a prototype is assembled and tested under different operating regimes. Experimental results are presented to demonstrate the performance of the developed prototype.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.681-686
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• 2017

태양광 모듈에서 태양전지를 연결해주는 인터커넥터로 리본 솔더로 SnPbAg가 사용되고, 옥외 태양광 발전에 장기간 노출시 리본의 부식으로 인한 열화가 흔히 관찰된다. 이러한 부식현상으로 인하여 리본과 태양전지의 접합이 약해져 접촉저항이 증가하고, 또한 리본 자체의 직렬 저항이 증가하게 되어 태양전지의 전압 전류 곡선에서 충진률 손실로 출력이 저하된다. 본 논문에서는 리본의 부식을 완화시킬 수 있는 방법으로 희생양극법을 이용하여 순수 알루미늄 및 아연, 알루미늄, 아연 그리고 마그네슘의 합금을 이용한 5가지 희생양극 소재의 부식에 의한 열화 저감을 연구하였다. 전기화학적 방법으로 희생양극 소재의 개방회로 전위와 폐쇄회로 전위를 측정하였고, 포텐시오다이나믹 분극 곡선을 측정하고, 영저항전류계를 이용하여 리본과 소재간의 갈바닉 전류를 측정하였다. 또한, 아세트산과, NaCl에 리본과 희생양극 소재의 부착 전후의 침지시험과 4셀 미니모듈로 제작한 후 1500시간 고온고습 시험 전후 출력을 평가하였다. 그 결과 Al-3Mg와 Al-3Zn-1Mg의 희생양극 소재가 부식속도가 느리고, 출력저하를 저감시킬 뿐만 아니라 장기 안정성에도 효과적인 것으로 평가된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.535-542
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• 2000

전차선로 가선재료에는 순수구리로 이루어진 전차선, 카드뮴이 포함된 조가선, steel과 Al의 이종금속으로 이루어진 ACSR이 있고 이들 재료는 산성비와 같은 부식환경에 노출되어 있다. 따라서 다양한 부식환경에서의 이들 재료의 부식특성 및 부식속도를 규명하는 것은 매우 중요한 일이다 이에 본 실험에서는 pH, 용존산소 및 염소이온의 영향을 동전위분극시험, 선형분극시험, 교류임피던스시험 및 갈바닉시험 등의 전기화학적 분석기법을 통해 가선재료의 부식거동 및 부식속도를 조사하였다. 실험 결과 카드뮴이 함유된 재료의 부식저항성이 순수구리로 이루어진 재료에서의 부식저항성보다 낮은 것을 확인하였고, 염소이온이 내식성을 감소시킨다는 것을 관찰하였으며, 갈바닉시험 결과 산성용액에서 염소이온을 첨가하였을 경우 steel의 높은 갈바닉부식 전류밀도를 ZRA 법을 통해 확인하였다.