• 대한금속재료학회지
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• 제46권9호
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• pp.577-584
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• 2008

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. So, it is essential to choose the optimum material for the process equipment handling molten salt. In this study, corrosion behavior of Inconel 713LC, Inconel MA 754, Nimonic 80A and Nimonic 90 in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere was investigated at $650^{\circ}C$ for 72~216 hrs. Inconel 713LC alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of Inconel 713LC were $Cr_2O_3$, $NiCr_2O_4$ and NiO, and those of Inconel MA 754 were $Cr_2O_3$ and $Li_2Ni_8O_{10}$ while $Cr_2O_3$, $LiFeO_2$, $(Cr,Ti)_2O_3$ and $Li_2Ni_8O_{10}$ were produced from Nimonic 80A. Also, corrosion products of Nimonic 90 were found to be $Cr_2O_3$, $(Cr,Ti)_2O_3$, $LiAlO_2$ and $CoCr_2O_4$. Inconel 713LC showed local corrosion behavior and Inconel MA 754, Nimonic 80A, Nimonic 90 showed uniform corrosion behavior.

• 대한금속재료학회지
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• 제46권10호
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• pp.646-651
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• 2008

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. It is essential to choose the optimum material for the process equipment handling molten salt. IN713LC is one of the candidate materials proposed for application in electrolytic reduction process. In this study, yttria-stabilized zirconia (YSZ) top coat was applied to a surface of IN713LC with an aluminized metallic bond coat by an optimized plasma spray process, and were investigated the corrosion behavior at $675^{\circ}C$ for 216 hours in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere. The as-coated and tested specimens were examined by OM, SEM/EDS and XRD, respectively. The bare superalloy reveals obvious weight loss, and the corrosion layer formed on the surface of the bare superalloy was spalled due to the rapid scale growth and thermal stress. The top coatings showed a much better hot-corrosion resistance in the presence of $LiCl-Li_2O$ molten salt when compared to those of the uncoated superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing to the hot-corrosion resistance of the structural materials for handling high temperature lithium molten salts.

• 한국재료학회지
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• 제23권2호
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• pp.128-134
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• 2013

A study on the corrosion behavior of Inconel alloys and Incoloy 800H in molten salt of LiCl-$Li_2O$ was investigated at $650^{\circ}C$ for 24-312 hours in an oxidation atmosphere. The order of the corrosion rate was Inconel 600 < Inconel 601 < Incoloy 800H < Inconel 690. Inconel 600 showed the best performance suggesting that the content of Fe, Cr and Ni are the important factor for corrosion resistance in hot molten salt oxidation conditions. The corrosion products of Inconel 600 and Inconel 601 were $Cr_2O_3$ and $NiFe_2O_4$, In case of Inconel 690, a single layer of $Cr_2O_3$ was formed in the early stage of corrosion and an outer layer of $NiFe_2O_4$ and inner layer of $Cr_2O_3$ were formed with an increase of corrosion time. In the case of Incoloy 800H, $Cr_2O_3$ and $FeCr_2O_4$ were observed. Most of the outer scale of the alloys was observed to be spalled from the results of the SEM analysis and the unspalled scale which adhered to the substrate was composed of three layers. The outer layer, the middle one, and the inner one were Fe, Cr, and Ni-rich, respectively. Inconel 600 showed localized corrosion behavior and Inconel 601, 690 and Incoloy 800H showed uniform corrosion behavior. Ni improves the corrosion resistance and too much Cr and/or Fe content deteriorates the corrosion resistance.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.920-926
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• 2021

Capsules containing NaCl-MgCl₂ salt with 316L stainless steel or alloy N samples were irradiated in the Ohio State University Research Reactor for 21 nonconsecutive hours. A custom irradiation vessel was designed for this purpose, and details on its design and construction are given. Stainless steel samples that were irradiated during exposure had less corrosive attack than samples exposed to the same conditions without irradiation. Alloy N samples showed no significant effect of irradiation. This work shows a method for conducting in-reactor irradiation-corrosion experiments in static molten salts and presents preliminary data showing that neutron irradiation may decelerate corrosion of alloys in molten chloride salts.

• 한국표면공학회지
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• 제31권4호
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• pp.223-230
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• 1998

The separator for a molten carbonate fuel cell(MCFC) is mode of stainless steel and known to the suscepibility to corrosion due to environments of high temperature molten carbonte electrolyte. Considering the sensitization of stainless steel in the temperature range of 425~$815^{\circ}C$, the separator is expected to be sensitized so that the interganular corrosion (IGC) occurs during the cell operation at about $650^{\circ}C$. In this study, EPR(electrochemical potentiokinetic reactivation) technique was examined by relating some elements(mainly C and Cr) to the degree of sensitization of austenitic stainless steels in the molten carbonate salt at $650^{\circ}C$and the possible mechanism of intergranular corrosion was analyzed.

• 한국재료학회지
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• 제9권6호
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• pp.556-563
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• 1999

The corrosion behavior of heat-resistant alloys, More 1 and Super 22H in molten salts of LiCl and $LiCl-Li_2$O was investigated in the temperature range of $650~850^{\circ}C$. In a molten salt of LiCl, a dense protective oxide scale of $LiCrO_2$ was formed, following growth of oxide scale with parabolic kinetics. But in a mixed molten salt of LiCl, a dense protective oxide scale of $LiCrO_2$ was formed, following growth of oxide scale with parabolic kinetics. But in a mixed molten salt of $LiCl-Li_2$O, a porous non-protective scale of Li\ulcorner(Cr, Ni, Fe)\ulcornerO$_2$was formed, following growth of oxide scale with linear kinetics. The corrosion rate increased slowly with the increase of temperature up to $750^{\circ}C$, but above $750^{\circ}C$ rapid increase in corrosion rate observed. The corrosion behavior of Super 22H alloy was similar to that of More 1 alloy, but Super 22H showed higher corrosion resistance than More 1.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1727-1732
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• 2017

Pyroprocessing is an alternative method of reprocessing spent fuel, usually involving the dissolving spent fuel in a molten salt media. The National Nuclear Laboratory designed, built, and commissioned a molten salt dynamics rig to investigate the transfer characteristics of molten lithium chloride-potassium chloride eutectic salt. The efficacy and flow characteristics of a high-temperature centrifugal pump and argon gas lift were obtained for pumping the molten salt at temperatures up to $500^{\circ}C$. The rig design proved suitable on an industrial scale and transfer methods appropriate for use in future molten salt systems. Corrosion within the rig was managed, and melting techniques were optimized to reduce stresses on the rig. The results obtained improve the understanding of molten salt transport dynamics, materials, and engineering design issues and support the industrialization of molten salts pyroprocessing.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.285-291
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• 2004

LiCl-$Li_2O-O_2$ 용융염계에서 용융염 취급장치의 구조재료를 위한 평가의 일환으로 Inconel 718, X-750, Haynes 75, 263 합금의 부식거동을 분위기온도; $650^{\circ}C$, 부식시간: 24~168h, $Li_2O$농도; 3wt%, 혼합가스농도; Ar-10%$O_2$에서 조사하였다. LiCl-$Li_2O-O_2$ 용융염계에서 부식속도는 Haynes 263 ＜ Haynes 75 ＜ Inconel X-750 ＜ Inconel 718 순서로 나타났으며, Haynes 263 합금이 가장 우수한 내부식성을 나타내었다. Haynes 75의 부식생성물은 $Cr_2O_4$, $NiFe_2O_4$, $LiNiO_2$, $Li_2NiFe_2O_4$, Inconel 718의 부식생성물은 $Cr_2O_4$ 및 $NiFe_2O_4$ 이며 Haynes 263은 $Li(Ni,Co)O_2$, $NiCr_2O_4$ 및 $LiTiO_2$, Inconel X-750은 $Cr_2O_3$, $NiFe_2O_4$,$FeNi_3$, (Al,Nb,Ti)$O_2$의 부식생성물을 나타내었다. Haynes 263은 국부부식의 거동을 보이는 반면, Haynes 75, Inconel 718 및 Inconel X-750은 전면 부식 거동을 나타내었다.

• 방사성폐기물학회지
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• 제20권2호
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• pp.209-229
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• 2022

This work provided a review of three techniques-(1) spectrochemical, (2) electrochemical, and (3) spectroelectrochemical-for molten salt medias. A spectroelectrochemical system was designed by utilizing this information. Here, we designed a spectroelectrochemical cell (SEC) and calibrated temperature controllers, and performed initial tests to explore the system's capability limit. There were several issues and a redesign of the cell was accomplished. The modification of the design allowed us to assemble, align the system with the light sources, and successfully transferred the setup inside a controlled environment. A preliminary run was executed to obtain transmission and absorption background of NaCl-CaCl₂ salt at 600℃. It shows that the quartz cuvette has high transmittance effects across all wavelengths and there were lower transmittance effects at the lower wavelength in the molten salt media. Despite a successful initial run, the quartz vessel was mated to the inner cavity of the SEC body. Moreover, there was shearing in the patch cord which resulted in damage to the fiber optic cable, deterioration of the SEC, corrosion in the connection of the cell body, and fiber optic damage. The next generation of the SEC should attach a high temperature fiber optic patch cords without introducing internal mechanical stress to the patch cord body. In addition, MACOR should be used as the cell body materials to prevent corrosion of the surface and avoid the mating issue and a use of an adapter from a manufacturer that combines the free beam to a fiber optic cable should be incorporated in the future design.

• 한국재료학회지
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• 제8권8호
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• pp.685-692
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• 1998

용융탄산염 연료전지는 $650^{\circ}C$의 부식성이 강한 용융탄산염내에서 작동되므로, 분리판 재료로 사용되고 있는 316L 스테인레스강의 부식은 용융탄산염 연료전지의 수명을 단축시키는 주요한 원인이다. 특히 분리판 wet-seal부의 부식은 보다 심각한 것으로 알려져 있다. 이를 해결하기 위하여 AI계 합금이 피복재료로 사용되어 왔지만, 본 연구에서는 보다 우수한 분리판 wet-seal부의 내식 피복재료 개발을 위하여 피복재료인 NiAI 합금에 산화 활성화 원소인 yttrium을 최고 1.5 at%까지 첨가하였다. $650^{\circ}C$의 용융탄산염내에서 yttium 함량에 따른 NiAI/Y 합금의 침지부식실험 및 분극실험을 통하여 내식성을 평가하고 부식 억제를 위해 가장 적절한 NiAI/Y 피복 재료의조성을 결정한 결과 최소의 yttrium 조성은 0.7 at% 임을 알 수 있었다.