• Title/Summary/Keyword: NiMo

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Corrosion Behavior of Bimetal Materials (Fe-Ni / Fe-Ni-Mo) for Electromagnetic Switches (전자 개폐기용 바이메탈 소재(Fe-Ni / Fe-Ni-Mo)의 부식거동)

  • Yu-Jeong An;Eun-Hye Hwang;Jae-Yeol Jeon;Sung Jin Kim
    • Corrosion Science and Technology
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    • v.22 no.6
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    • pp.478-483
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    • 2023
  • This study examined the corrosion behavior of bimetal materials composed of Fe-Ni alloy and Fe-Ni-Mo alloy, both suitable for use in electromagnetic switches. Electrochemical polarization and weight loss measurements revealed that, in contrast to Fe-Ni alloy, which exhibited pseudo-passivity behavior, Fe-Ni-Mo alloy had higher anodic current density, displaying only active dissolution and greater weight loss. This indicated a lower corrosion resistance in the Fe-Ni-Mo alloy. Equilibrium calculations for the phase fraction of precipitates suggested that the addition of 1 wt% Mo may lead to the formation of second-phase precipitates, such as Laves and M6C, in the γ matrix. These precipitates might degrade the homogeneity of the passive film formed on the surface, leading to localized attacks during the corrosion process. Therefore, considering the differences in corrosion kinetics between these bimetal materials, the early degradation caused by galvanic corrosion should be prevented by designing a new alloy, optimizing heat treatment, or implementing periodic in-service maintenance.

Dependence of giant magnetoimpedance on aspect ratio and thickness of electrode layer for phto-lithograpically patterned $Ni_{79}Fe_{18}Mo_{5}\%/Ag/Ni_{79}Fe_{18}Mo_{5}\%$ multilayer (사진공정으로 제작된 $Ni_{79}Fe_{18}Mo_{5}\%/Ag/Ni_{79}Fe_{18}Mo_{5}\%$ 박막의 전도층 형상비 및 두께에 따른 자기 임피던스 효과)

  • 이기언;이두현;정근희;윤성용;임태완;장대영;김용성;서수정
    • Proceedings of the Korean Magnestics Society Conference
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    • 2004.12a
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    • pp.80-80
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    • 2004
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Fabrication of Ni-Mo-based Electrocatalysts by Modified Zn Phosphating for Hydrogen Evolution Reaction

  • Im, Han Seo;Park, Seon Ha;Ha, Hyo Jeong;Lee, Sumin;Heo, Sungjun;Im, Sang Won;Nam, Ki Tae;Lim, Sung Yul
    • Journal of Electrochemical Science and Technology
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    • v.13 no.1
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    • pp.54-62
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    • 2022
  • The preparation of low-cost, simple, and scalable electrodes is crucial for the commercialization of water electrolyzers for H2 production. Herein, we demonstrate the fabrication of cathodes through Mo-modified Zn phosphating of Ni foam (NiF) for water electrolysis, which has been largely utilized in surface coating industry. In situ growth of electrocatalytically active layers in the hydrogen evolution reaction (HER) was occurred after 1 min of phosphating to form ZnNiMoPi, and subsequent thermal treatment and electrochemical activation resulted in the formation of ZnNiMoPOxHy. ZnNiMoPOxHy exhibited superior HER performance than NiF, primarily because of the increased electrochemically active surface area of ZnNiMoPOxHy compared to that of bare NiF. Although further investigations to improve the intrinsic electrochemical activity toward the HER and detailed mechanistic studies are required, these results suggest that phosphating is a promising coating method and will possibly advance the fabrication procedure of electrodes for water electrolyzers with better practical applications.

High-valence Mo doping for promoted water splitting of Ni layered double hydroxide microcrystals

  • Kyoungwon Cho;Seungwon Jeong;Je Hong Park;Si Beom Yu;Byeong Jun Kim;Jeong Ho Ryu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.33 no.2
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    • pp.78-82
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    • 2023
  • The oxygen evolution reaction (OER) is the primary challenge in renewable energy storage technologies, specifically electrochemical water splitting for hydrogen generation. We report effects of Mo doping into Ni layered double hydroxide (Ni-LDH) microcrystal on electrocatalytic activities. In this study, Mo doped Ni-LDH were grown on three-dimensional porous nicekl foam (NF) by a facile solvothermal method. Homogeneous LDH structure on the NF was clearly observed. However, the surface microstructure of the nickel foam began to be irregular and collapsed when Mo precursor is doped. Electrocatalytic OER properties were analyzed by Linear sweep voltammetry (LSV) and Electrochemical impedance spectroscopy (EIS). The amount of Mo doping used in the electrocatalytic reaction was found to play a crucial role in improving catalytic activity. The optimum Mo amount introduced into the Ni LDH was discussed with respect to their OER performance.

Characterization of Oxide Scales Formed on Ni3Al-7.8%Cr-1.3%Zr-0.8%Mo-0.025%B (Ni3Al-7.8%Cr-1.3%Zr-0.8%Mo-0.025%B 합금의 고온산화막분석)

  • Kim, Gi-Yeong;Lee, Dong-Bok
    • Korean Journal of Materials Research
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    • v.12 no.3
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    • pp.220-224
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    • 2002
  • The oxide scales formed on $Ni_3Al$-7.8%Cr-1.3%Zr-0.8%Mo-0.025%B after oxidation at 900, 1000 and 110$0^{\circ}C$ in air were studied using XRD, SEM, EPMA and TEM. The oxide scales consisted primarily of $NiO,\; NiAl_2O_4,\;{\alpha}-Al_2O_3,\; monoclinic-ZrO_2,\; and \;tetragonal-ZrO_2$. The outer layer of the oxide scale was rich in Ni-oxides, whereas the internal oxide stringers were rich in Al-oxides and $ZrO_2$. Within the above oxide scales, Cr and Mo tended to exist as dissolved ions.

Microstructures of W-Mo-Ni-Fe Heavy Alloys

  • Lin, Kuan-Hong;Hsu, Chen-Siang;Lin, Shun-Tian
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.937-938
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    • 2006
  • Tungsten heavy alloys with different ratios of Mo and Ni-Fe matrix were liquid-phase-sintered to investigate their microstructural evolution. Results indicated that increased Mo in the alloy promoted the formation of a (W,Mo)(Ni,Fe) type intermetallic compound in the furnace-cooled condition. It was a monoeutectic reaction when the added Mo content was higher than 49at.%, or a eutectic reaction when this value was between 37at,% to 49at.%. When Mo was added between 25at.% to 37at.%, the precipitation of the intermetallic compound took place by either a eutectoid or peritectoid reaction.

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Thermodynamic Calculation and Observation of Microstructural Change in Ni-Mo-Cr High Strength Low Alloy RPV Steels with Alloying Elements (압력용기용 Ni-Mo-Cr계 고강도 저합금강의 합금원소 함량 변화에 따른 미세조직학적 특성변화의 열역학 계산 및 평가)

  • Park, Sang Gyu;Kim, Min-Chul;Lee, Bong-Sang;Wee, Dang-Moon
    • Korean Journal of Metals and Materials
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    • v.46 no.12
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    • pp.771-779
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    • 2008
  • An effective way of increasing the strength and fracture toughness of reactor pressure vessel steels is to change the material specification from that of Mn-Mo-Ni low alloy steel(SA508 Gr.3) to Ni-Mo-Cr low alloy steel(SA508 Gr.4N). In this study, we evaluate the effects of alloying elements on the microstructural characteristics of Ni-Mo-Cr low alloy steel. The changes in the stable phase of the SA508 Gr.4N low alloy steel with alloying elements were evaluated by means of a thermodynamic calculation conducted with the software ThermoCalc. The changes were then compared with the observed microstructural results. The calculation of Ni-Mo-Cr low alloy steels confirms that the ferrite formation temperature decreases as the Ni content increases because of the austenite stabilization effect. Consequently, in the microscopic observation, the lath martensitic structure becomes finer as the Ni content increases. However, Ni does not affect the carbide phases such as $M_{23}C_6 $ and $M_7C_3$. When the Cr content decreases, the carbide phases become unstable and carbide coarsening can be observed. With an increase in the Mo content, the $M_2C$ phase becomes stable instead of the $M_7C_3$ phase. This behavior is also observed in TEM. From the calculation results and the observation results of the microstructure, the thermodynamic calculation can be used to predict the precipitation behavior.

MoOx-Windowed High-Performing Transparent Photodetector (MoOx 기반의 고성능 투명 광검출기)

  • Park, Wang-Hee;Lee, Gyeongnam;Kim, Joondong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.6
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    • pp.387-392
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    • 2017
  • A high-performing all-transparent photodetector was created by configuring a $MoO_x$/NiO/ZnO/ITO structure on a glass substrate. The ITO bottom layer was applied as a back contact. To achieve the transparent p/n junction, p-type NiO was coated on the n-type ZnO layer. Reactive sputtering was used to spontaneously form the ZnO or NiO layer. In order to improve the transparent photodetector performance, the functional $MoO_x$ window layer was used. Optically, the $MoO_x$ window provided a refractive index layer (n=1.39) lower than that of NiO (n=2), increasing the absorption of the incident light wavelengths (${\lambda}s$). Moreover, the $MoO_x$ window can provide a lower sheet resistance to improve the carrier collection for the photoresponses. The $MoO_x$/NiO/ZnO/ITO device showed significantly better photoresponses of 877.05 (at ${\lambda}$=460nm), 87.30 (${\lambda}$=520 nm), and 30.38 (${\lambda}$=620 nm), compared to 197.28 (${\lambda}$=460 nm), 51.74 (${\lambda}$=520 nm) and 25.30 (${\lambda}$=620 nm) of the NiO/ZnO/ITO device. We demonstrated the high-performing transparent photodetector by using the multifunctional $MoO_x$ window layer.

Preparation and Characteristics of the Ni-Ferrite Encapsulated Mo-Permalloy Powder

  • Park, Hyun-Kyu;Ji, In-Geol;Oh, Jae-Hee;Ko, Taeg-Yung
    • Journal of the Korean Ceramic Society
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    • v.43 no.11 s.294
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    • pp.700-702
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    • 2006
  • We prepared a Ni-ferrite encapsulated Mo-permalloy powder through simple electroless plating and heat treatment. It was observed that Ni-ferrite particles formed in a spherical form on each Mo-permalloy grain. The microstructure and the magnetic characteristics of the encapsulated powders depended strongly on oxidation time in the heat-treatment. When the powder was oxidized for 60 min, a dense Ni-ferrite layer covered the Mo-permalloy grain, which in turn exhibited high saturation magnetization of 85.8 emu/g. The magnetic core prepared additionally with the encapsulated powder exhibited a resonant frequency of 12 kHz.