• Title/Summary/Keyword: sealing performance at low temperature

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Effect of Phenyl Vinyl Methyl Silicone (PVMQ) on Low Temperature Sealing Performance of Fluorosilicone Composites

  • Lee, Jin Hyok;Bae, Jong Woo;Choi, Myoung Chan;Yun, Yu-Mi;Jo, Nam-Ju
    • Elastomers and Composites
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    • v.56 no.4
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    • pp.209-216
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    • 2021
  • In this study, we observed the mechanical properties, thermal stability, and low temperature sealing performance of fluorosilicone elastic composites. When the blend ratio of Phenyl vinyl methyl silicone (PVMQ) was increased, the tensile strength, modulus at 100%, and compression set were decreased. The thermal stability of fluorosilicone elastic composites showed a similar tendency. These were caused by poorer green strength of PVMQ than Fluorosilicone rubber (FVMQ). The change in the tensile strength and elongation at -40℃ showed a decreasing tendency with increasing PVMQ blend ratio. By increasing the PVMQ blend ratio, low-temperature performance was improved. The Dynamic mechanical analysis (DMA) results showed that Tg was decreased and low-temperature performance was improved with increasing PVMQ blend ratio. However tanδ was decreased becaused of the poor green strength and elasticity of PVMQ. From a hysteresis loss at -40℃, the hysteresis loss value was increased and fluorosilicone elastic composites showed the decreasing tendency of elasticity with increasing PVMQ blend ratio. From the TR test, TR10 was decreased with increasing PVMQ blend ratio. FS-4 (45% PVMQ blended composites) showed a TR10 of -68.0℃ that was 5℃ lower than that of FS-1 (100% FVMQ). The gas leakage temperature was decreased with increasing PVMQ blend ratio. The gas leakage temperature of FS-4 was -69.2℃ that was 5℃ lower than that of FS-1. Caused by the polymer chain started to transfer from a glassy state to a rubbery state and had a mobility of chain under Tg, the gas leakage temperature showed a lower value than Tg. The sealing performance at low temperature was dominated by Tg that directly affected the mobility of the polymer chain.

Investigation of Glass Substrate Sealing for ECL Application using Laser Welding Technology (레이저 웰딩 기술을 이용한 ECL용 유리 기판 접합에 대한 고찰)

  • Sung, Youl-Moon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.12
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    • pp.28-32
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    • 2015
  • In this work, we reported fabrication of sealing the glass substrate using laser treatment at low temperature for electrochemical luminescence (ECL) cell. The laser treatment at temperature is using laser diode. The glass substrate sealing by laser treatment tested at 3-10W, 2-5 mm/s for build and tested. The sealing laser treatment method will allow associate coordination between the two glass substrate was enclosed. The effect of laser treatment to sealing the glass substrate was found to have cracks and air gap at best thickness of about 550-600 im for condition 3 W, 3 mm/s. The surface of sealing was roughness which was not influent to electrodes It can reduce the cracks, crevices and air gaps as well, improves the performance viscosity in butter bus bar electrodes. Therefore, it is more effective viscosity between two FTO glasses substrate.

Application of Au-Sn Eutectic Bonding in Hermetic Rf MEMS Wafer Level Packaging (Au-Sn 공정 접합을 이용한 RF MEMS 소자의 Hermetic 웨이퍼 레벨 패키징)

  • Wang Qian;Kim Woonbae;Choa Sung-Hoon;Jung Kyudong;Hwang Junsik;Lee Moonchul;Moon Changyoul;Song Insang
    • Journal of the Microelectronics and Packaging Society
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    • v.12 no.3 s.36
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    • pp.197-205
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    • 2005
  • Development of the packaging is one of the critical issues for commercialization of the RF-MEMS devices. RF MEMS package should be designed to have small size, hermetic protection, good RF performance and high reliability. In addition, packaging should be conducted at sufficiently low temperature. In this paper, a low temperature hermetic wafer level packaging scheme for the RF-MEMS devices is presented. For hermetic sealing, Au-Sn eutectic bonding technology at the temperature below $300{\times}C$ is used. Au-Sn multilayer metallization with a square loop of $70{\mu}m$ in width is performed. The electrical feed-through is achieved by the vertical through-hole via filled with electroplated Cu. The size of the MEMS Package is $1mm\times1mm\times700{\mu}m$. By applying $O_2$ plasma ashing and fabrication process optimization, we can achieve the void-free structure within the bonding interface as well as via hole. The shear strength and hermeticity of the package satisfy the requirements of MIL-STD-883F. Any organic gases or contamination are not observed inside the package. The total insertion loss for the packaging is 0.075 dB at 2 GHz. Furthermore, the robustness of the package is demonstrated by observing no performance degradation and physical damage of the package after several reliability tests.

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On the Contact Behavior Analysis and New Design of O-ring Seals

  • Kim, Chung-Kyun;Cho, Seung-Hyun;Kim, Young-Gyu
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.121-122
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    • 2002
  • This paper presents contact behavior of an Polyperfluoroalkoxyethylene(PTFE) ring seals by a non-linear finite element method using the thermomechanical analysis. PTFE elastomer was assumed as odgen model for numerical analysis in FEM commercial code because elastomer has nonlinear behaviour character. The shape effects are investigated for sealing performance of ring seal in boundary conditions which as gas pressure, groove temperature and various O-ring seal models. Also contact stress and equivalent total strain are investicated. An O-ring seals was modeled four shape which are circle, two sunflower and X. The highest contact stress occurs at sunflower-ring seal with groove deapth of 0.35mm. the equivalent total strain of sunflower-ring seal is lower than that of the others under low gas pressure condition but under gas pressure condition over 4Mpa, that of sunflower-ring seal is higher. The calculated FEM results shows that the Sunflower-ring seal with groove depth of 0.35mm has excellent performance compared with other seal models.

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Fabrication Characteristics and Performance Evaluation of a Large Unit Cell for Solid Oxide Fuel Cell (고체산화물연료전지용 대면적 단위전지 제조특성 및 성능평가)

  • Shin, Y.C.;Kim, Y.M.;Oh, I.H.;Kim, H.S.;Lee, M.S.;Hyun, S.H.
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.05a
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    • pp.13-16
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    • 2008
  • Solid oxide fuel cell(SOFC) is an electrochemical energy conversion system with high efficiency and low-emission of pollution. In order to reduce the operating temperature of SOFC system under $800^{\circ}C$, the thickness reduction of YSZ electrolyte to be as thin as possible, e.g., less than 10 ${\mu}m$ are considered with the microstructure control and optimum design of unit cell. Methods for reducing the thickness of YSZ electrolyte have been investigated in coin cell. Moreover, a large unit cell($8cm{\times}8cm$) for SOFC was fabricated using an anode-supported electrolyte assembly with a thinner electrolyte layer, which was prepared by a tape casting method with a co-sintering technique. we studied the design factors such as active layer, electrolyte thickness, cathode composition, etc,. by the coin type of unit cell ahead of the fabrication process of a large unit cell and also reviewed about the evaluation technique of a large size unit cell such as interconnect design, sealing materials and current collector and so forth. Electrochemical evaluations of the unit cells, including measurements such as power density and impedance, were performed and analyzed. Maximum power density and polarization impedance of coin cell were 0.34W/$cm^2$ and $0.45{\Omega}cm^2$ at $800^{\circ}C$, respectively. However, Maxium power density of a large unit cell($5cm{\times}5cm$) decreased to 0.21W/$cm^2$ at $800^{\circ}C$ due to the increase of ohmic resistance. However, It was found that the potential value of a large unit cell loaded by 0.22A/$cm^2$ showed 0.76V at 100hrs without the degradation of unit cell.

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A Study on the Thermal Stability of Long-Term Fuel Storage and Lifetime Estimation of Rubber O-ring in Contacted with Fuel (장기 저장연료의 열안정성 및 연료접촉 고무오링의 수명예측 연구)

  • Chung, K.W.;Hong, J.S.;Kim, Y.W.;Han, J.S.;Jeong, B.H.;Kwon, T.S.;Suh, D.O.;Sung, M.J.;Kwon, Y.I.
    • Tribology and Lubricants
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    • v.34 no.5
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    • pp.197-207
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    • 2018
  • Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.