• 한국산업융합학회 논문집
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• 제27권3호
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• pp.573-580
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• 2024

Recently, the special alloy, for instance, such as Monel and Inconel, is used for valves, bolt/nuts, and fittings in semiconductor facility, FCEV(fuel cell electric vehicle) and hydrogen gas station, to reduce the hydrogen embrittlement. Even though the Monel material has high cost, it is recommended to use for the cases of ultra high pressure, ultra high leak-proof and so on. The purpose of this study is to investigate the characteristics of Monel material within elastic limit through the comparative analysis when Monel material is extruded or drawn. As the results, the deformation of Monel material was increased as the number of pass was increased, further, the deformation of Monel material by drawing was larger than that by extrusion. In the safety factor, the case that load is less than 420kN, the plastic deformation due to drawing could be happened faster than that due to extrusion. However, the case of more than 420kN, it showed that the plastic deformation for extrusion and drawing was almost similar.

• 한국산업융합학회 논문집
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• 제25권6_2호
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• pp.961-968
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• 2022

Hydrogen embrittlement leads to the damages in bolts, nut, especially, high pressure valves, in the semiconductor facilities, hydrogen vehicles, hydrogen stations and so on. Monel material has higher strength than SUS material. Therefore, even though Monel material with special alloy is usually used to prevent the hydrogen embrittlement, it needs powerful drawing system to manufacture the rectangular or hexagonal bar using circular bar. The purpose of this study is to investigate the characteristics of plastic deformation of Monel material and 2 rollers of rolling unit in plastic limit through numerical analysis. As the results, it was predicted that, based on mean stress, as the rolling step was increased, the rolling force of rolling unit was decreased. In addition, the heat treatment for Monel material was needed because of residual stress due to plastic deformation. As for rollers, the roller was safe about 1.86 times compared with that of ultimate strength. In this study, as the roller 2 showed larger stress than roller 1, thus, roller 2 should be designed carefully to guarantee the safety. Further it was confirmed that the reaction force of roller could be helpful in bearing design.

• 한국표면공학회지
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• 제29권4호
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• pp.278-285
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• 1996

The structure of coating layer formed by hot dip Al-Cu alloy coating on Monel 1400 metal was studied. The coating layer consists of alloyed layer adjacent to the Monel 400 substrate and Al-Cu alloy. It was found that the hardness of coating increased with dipping time and heat treatment associated with the diffusion and the formation of intermetallic compound at the interface. However the thickness of coating layer was decreased at high dipping temperature due to tile higher viscosity of liquid coating alloy. Diffusion heat treatment at $600^{\circ}C$ after coating resulted in the disappearence of adhered Al(Cu) and $CuAl_2$ phases, and then they transformed into the new phases of CuAl and Al7Cu4Ni at coating layer.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.19-21
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• 1997

• 한국산학기술학회논문지
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• 제17권11호
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• pp.42-50
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• 2016

오버레이 용접은 희석율에 의해 적층 두께에 따라 화학성분 함량과 용접부의 경도에 영향을 미치며 이는 파이프 제품의 표면성질을 결정한다. 이로 인해 오버레이 용접은 적층의 수를 고려하여야 한다. 본 연구에서는 탄소강 모재에 내부식성 소재인 모넬 소재를 오버레이 용접하여 적층수에 따른 Fe함량, 모재와 모넬 소재와의 용접성, 부위별 경도와 표면 평탄도를 실험적으로 연구하였다. 각각의 평가는 평판의 모재와 파이프 모재에 3개의 층으로 오버레이 용접 후 실시하였다. Fe함량은 각 층별 시료를 채취하여 성분 분석을 통해 평가하였으며, 3Layer에서 만족하는 함량을 나타내었다. 또한 적층별 시편을 밴딩 시험하여 용접성을 평가하였다. 적층별 경도와 비드 평탄도는 Micro Vickers와 3차원 측정을 통해 평가하였다. 경도는 1Layer에서 발생하는 HAZ부에 의해 가장 높은 경도 값을 보였으며, 적층이 증가할수록 경도가 감소하였다. 비드 평탄도의 경우 적층수 증가에 따라 편차가 급격한 차이가 발생하였으며, 이는 경도와 함께 사용 목적의 측면에서 주의 깊게 고려해야 한다. 이러한 실험적 결과는 목적에 따른 용접 파이프 적층수의 결정 방법을 나타내었다.

• 한국정밀공학회지
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• 제25권4호
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• pp.100-107
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• 2008

Bellows is an important component in Joule-Thomson cryocooler, which minimize the excessive flow of the cryogenic gas. The bellows is made of Monel 400 and its geometry is an axial symmetric shell. During cool-down process, the pressure and volume within bellows must be satisfied with Benedict-Webb-Rubin state equation. Moreover, Poisson's ratio of Monel 400 is nearly constants, but its Young's modulus varies for a drop in temperature. Under these conditions, bellows contracts in the axial direction like a spring. To evaluate deformation of bellows at cryogenic temperature, the numerical calculation of the volume within bellows and finite element analysis are iteratively used in this research. the numerical results show that deformation of the bellows is approximately linear for change of temperature.

• 한국안광학회지
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• 제20권1호
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• pp.9-14
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• 2015

목적: 본 논문에서는 안경테가 땀에 노출되었을 때 나타나는 변화를 알아보았다. 방법: 양백, 모넬 및 티타늄 재질의 안경테를 pH 6.5, 6.0, 5.0의 인공땀에 1주, 3주, 6주 동안 노출시킨 후 표면, 경도, 인장강도의 변화를 알아보았다. 결과: 인공땀에 의해 양백, 모넬, 티타늄 재질 안경테 표면의 부식이 유발되었으며 부식 양상은 각 재질별로 상이하였다. 인공땀의 pH와 노출시간에 비례하여 3가지 재질의 안경테 모두 경도가 감소하였으나 인장강도는 변화가 없었다. 결론: 인공땀에 의해 안경테의 표면 부식과 경도 변화가 관찰되었으므로 안경테의 일상적인 관리가 필요함을 제안한다.

• Steel and Composite Structures
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• 제44권1호
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• pp.17-31
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• 2022

This investigation studies the characteristics of wave dispersion in sigmoid functionally graded (SFG) curved beams lying on an elastic substrate for the first time. Homogenization process was performed with the help of sigmoid function and two power laws. Moreover, various materials such as Zirconia, Alumina, Monel and Nickel steel were explored as curved beams materials. In addition, curved beams were rested on an elastic substrate which was modelled based on Winkler-Pasternak foundation. The SFG curved beams' governing equations were derived according to Euler-Bernoulli curved beam theory which is known as classic beam theory and Hamilton's principle. The resulted governing equations were solved via an analytical method. In order to validate the utilized method, the obtained outcomes were compared with other researches. Finally, the influences of various parameters, including wave number, opening angle, gradient index, Winkler coefficient and Pasternak coefficient were evaluated and indicated in the form of diagrams.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.1-5
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• 2016

Field and temperature dependence of the critical current density, Jc, were measured for both un-doped and carbon doped $MgB_2/Nb/Monel$ wires manufactured by Hyper Tech Research, Inc. In particular, carbon incorporation into the $MgB_2$ structure using malic acid additive and a chemical solution method can be advantageous because of the highly uniform mixing between the carbon and boron powders. At 4.2 K and 10 T, Jc was estimated to be $25,000-25,300Acm^{-2}$ for the wire sintered at $600^{\circ}C$ for 4 hours. The irreversibility field, $B_{irr}$, of the malic acid doped wire was approximately 21.0 - 21.8 T, as obtained from a linear extrapolation of the J-B characteristic. Interestingly enough, the Jc of the malic acid doped sample exceeds $10^5Acm^{-2}$ at 6 T and 4.2 K, which is comparable to that of commercial Nb-Ti wires.

• 대한기계학회논문집A
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• 제33권3호
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• pp.201-209
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• 2009

The objective of present research work is to design the heat conductive mould to improve cooling characteristics of the injection mould for a mouse. In order to obtain the high cooling rate of the mould, a heat conductive mould with three different materials was designed. The materials of the base structure, the mid-layer and the molding part of the heat conductive mould were chosen as Cu-Ni alloy (Ampcoloy 940) to improve the heat conductivity of the mould, Ni-Cu alloy (Monel 400) to reduce a thermal stress, injection tool steel (P21), respectively. Through the three-dimensional transient heat transfer analysis and the thermal stress analysis, the effects of the geometrical arrangement of each material on the cooling characteristics and the thermal stress distribution were examined. From the results of the analyses, a proper design of the thermal conductive mould was obtained.