• Title/Summary/Keyword: Casting Process

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Fabrication Process and Characterization of High Thermal Conductivity-Low CTE SiCp/Al Metal Matrix Composites by Pressure Infiltration Casting Process (가압함침법에 의한 고열전도도-저열팽창계수 SiCp/Al 금속복합재료의 제조공정 및 특성평가)

  • 이효수;홍순형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 1999.11a
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    • pp.83-87
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    • 1999
  • The fabrication process and thermal properties of 50~71vol% SiCp/Al metal matrix composites (MMCs) were investigated. The 50~71vol% SiCp/Al MMCs fabricated by pressure infiltration casting process showed that thermal conductivities were 118~170W/mK and coefficient of thermal expansion (CTE) were 9.5~$6.5{\times}10^{-6}/K$. Specially, the thermal conductivity and CTE of 71vol%SiCp/Al MMCs were 115~156W/mK and 6~$7{\times}10^{-6}/K$. respectively, which showed a improved themal properties than the conventional electronic packaging materials such as ceramics and metals.

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Changes in Microstructure and Mechanical Properties due to Heat Treatment of Mg-1.0Al-1.0Zn-0.2Mn-0.5Ca Alloy Sheet Manufactured via Normal Casting and Twin Roll Casting Process (일반주조 및 쌍롤주조 공정으로 제조된 Mg-1.0Al-1.0Zn-0.2Mn-0.5Ca 합금 판재의 열처리에 따른 미세조직 및 기계적 특성 변화)

  • Dong Hwan Eom;No Jin Park
    • Journal of the Korean Society for Heat Treatment
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    • v.36 no.6
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    • pp.359-366
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    • 2023
  • Changes in microstructure and mechanical properties of Mg-1.0Al-1.0Zn-0.2Mn-0.5Ca (AZMX1100) alloy sheet manufactured by normal casting and twin roll casting process, were studied according to process and heat treatment. Non-uniform microstructure was observed in the initial sheet produced through both processes, and in particular, tilted dendrites and shifted central segregation were observed in the twin roll casting sheet. It was homogenized through hot rolling and heat treatment, and heat treated at 350℃ and 400℃ to compare the effect of heat treatment temperature. Both sheets were homogenized by the hot rolling process, and the grain size increased as the heat treatment temperature and time increased. It was confirmed that the grain size, deviation, and distribution of the second phase were finer and more homogenized in the TRC sheet. Accordingly, mechanical properties such as hardness, formability, and tensile strength also showed better values. However, unlike other previously reported AZMX alloy systems, it showed low formability (Erichsen value), which was judged by the influence of Al2Ca present in the microstructure.

A Study on the Die-casting Process of AM50 Magnesium Alloy (AM50 마그네슘 합금의 다이캐스팅 공정에 관한 연구)

  • Kim, Soon-Kook;Jang, Chang-Woo;Lee, Jun-Hee;Jung, Chan-Hoi;Seo, Yong-Gwon;Kang, Choong-Gil
    • Korean Journal of Materials Research
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    • v.16 no.8
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    • pp.516-523
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    • 2006
  • In recent years, Magnesium (Mg) and its alloys have become a center of special interest in the automobile industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die-casting parts can be easily produced. The die casting process is a fast production method capable of a high degree of automation for which certain Mg alloys are ideally suited. In this study, step-dies and flowability tests for AM50 were performed by die-casting process according to various combination of casting pressure and plunger velocity. We were discussed to velocity effect of forming conditions followed by results of microstructure, FESEM-EDX, hardness and tensile strength. Experimental results represented that the conditions of complete filling measured die-casting pressure 400 bar, 1st plunger velocity 1.0 m/s and 2nd plunger velocity 6.0 m/s. The increasing of 2nd plunger velocity 4.0 to 7.0 m/s decreased average grain size of $\alpha$ phase and pore. It was due to rapid filling of molten metal, increasing of cooling rate and pressure followed by increased 2nd plunger velocity. The pressure should maintain until complete solidification to make castings of good quality, however, the cracks were appeared at pressure 800bar over.

Fabrication Process and Forming Analysis of Fuel Cell Bipolar Plate by Injection Condition of Vacuum Die Casting (진공 다이캐스팅 공법의 사출조건에 따른 연료전지용 분리판 성형 해석 및 제조 공정)

  • Jin, Chul-Kyu;Jang, Chang-Hyun;Kim, Jae-Sung;Choi, Jae-Won;Kang, Chung-Gil
    • Journal of Korea Foundry Society
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    • v.31 no.5
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    • pp.274-283
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    • 2011
  • The vacuum die casting is a promising candidate of the stamping process for fabrication of fuel cell bipolar plate due to its advantages, such as precision casting, mass production and short production time. This study proposes vacuum die casting process to fabricate bipolar plates in fuel cell. Bipolar plates were fabricated under various injection conditions such as molten metal temperature and injection velocity. Also, according to injection velocity conditions, simulation results of MAGMA soft were compared to the experimental results. In case of melt temperature $650^{\circ}C$, misrun occurred. When the melt temperature was $730^{\circ}C$, mechanical properties were low due to dendrite microstructure. Injection velocity has to set at more than 2.0 m/s to fabricate the sound sample. When melt temperature, injection velocity (Fast shot), and vacuum pressure are $700^{\circ}C$, 2.5 m/s and 30 kPa respectively, sample had good formability and few casting defects. Simulation results are mostly in agreement with experimental results.

A Study on the Casting Process Variables and Optimum SrSO4 Content of the BSCCO(2212) Bulk Superconductor (BSCCO(2212) 벌크 초전도체의 주조조건 및 SrSO4 최적함량에 대한 연구)

  • Kim Kyu-Tae;Park Eui-Cheol;Jang Seok-Hern;Lim Jun-Hyung;Joo Jin-Ho;Kim Chan-Joong;Kim Hye-Rim;Hyun Ok-Bae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.6
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    • pp.579-585
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    • 2006
  • We fabricated BSCCO-2212 (2212) rod by the melt casting process (MCP) and evaluated the effect of the melt flowing on the critical current ($I_c$) by using vertical and tilt casting. It was observed that the $2212-SrSO_4$ rod processed by the tilt casting method with homogeneous pre-heating temperature of the mold had a higher $I_c$ than that processed by the vertical casting method. We also evaluated the influence of the strontium sulfates ($SrSO_4$) addition on the texture, microstructure, critical current and temperature, and mechanical hardness of the $2212-SrSO_4$ rods. It was observed that the addition of $SrSO_4$ improved the critical current ($I_c$) and mechanical hardness of the 2212. The $I_c$ of the 2212 increased as the $SrSO_4$ content increased and reached a peak value (260 A at 77 K) at an $SrSO_4$ content of 6 wt.%. In addition, the addition of $SrSO_4$ had a beneficial effect on the mechanical hardness of the 2212. We studied the possible cause of the variation in the $I_c$ with the melt flowing and the $SrSO_4$ content based on the XRD, EPMA analysis and the microstructural observation.

Effect of Pressure on Interfacial Heat Transfer Coefficient in the Squeeze Casting Process (용탕단조시 가압력에 따른 계면열전달계수의 변화)

  • Kim, Jin-Soo;Ahn, Jae-Young;Han, Yo-Sub;Lee, Ho-In;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.14 no.3
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    • pp.248-257
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    • 1994
  • Research in heat transfer and solidification commonly involves experimentation and mathematical modeling with associated numerical analysis and computation. Inverse problems in heat transfer are part of this paradigm. During the solidification of metal casting, an interfacial heat transfer resistance exists at the boundary between the casting and the mold, and this heat transfer resistance usually varies with time. In the case of the squeeze casting the contact heat transfer resistance is decreased by pressure and ideal contact is almost accomplished. In the present work, heat transfer coefficient, which is inverse value of the heat transfer resistance, was used for convenience. A numerical technique, Non-Linear Estimation has been adopted for calculation of the casting/mold interfacial heat transfer coefficient during the squeeze casting process. In this method, the measured temperature data from experiment were used. The computational results were applied to the analysis of heat transfer and solidification.

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Material Evaluation of Lead Die-Casted Positive Grid for Battery Using Nondestructive Evaluation Technique (연축전지 양극기판의 기계적 특성비교 분석 및 비 파괴 평가기법의 적용)

  • Kim, Hui-Jung;Lee, Min-Rae;Lee, Jun-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.8
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    • pp.1709-1718
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    • 2002
  • It is well recognized that improving capacity of positive grid in battery is one of key factors for controlling the expected long lift-time of Battery Energy Storage System(B.E.S.S). Thus it is really important to characterized material properties of positive grid which are mainly affected by fabrication process. In this study, two kinds of positive grids, which were fabricated by gravity casting and die-casting technique were used. Micro-structural observation and tensile test were conducted to investigate the effect of fabrication process of positive grid. Ultrasonic measurement based on pulse-echo method and ultrasonic C-scan technique also performed to correlate ultrasonic velocity with porosity ratio in positive grid. It was found that the porosity ratio of grid fabricated by gravity casting technique increased significantly compared to the grid fabricated by die-casting technique. It was also shown that ulrasonic technique is effective to evaluate the porosity ratio in positive grid.

A Study on the Development of Marine Turbocharger Nozzle Ring using Investment Casting (인베스트먼트법을 이용한 선박용 대형 터보차져 노즐링 개발을 위한 연구)

  • Hwang, Seong Ju;Lee, Man Gil;Jung, Jin Wook;Kwon, Soon Kook;Lee, Choon Man
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.8
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    • pp.671-675
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    • 2014
  • Nozzle ring is an important part of turbocharger which is applied to today's most diesel engines. Turbo charger nozzle ring is difficult to process and takes a high cost and a long time relatively. For this reason, it is largely produced by using a precision casting. Investment method, the representative technology of precision casting, has excellent dimensional accuracy and can produce complex shapes relatively easily. However, it is difficult to avoid the casting defects such as shrinkage cavity and short shot. This study is to predict the casting defects which could be occurred during the investment method by use of finite element analysis software and to design the process and mold of the marine turbocharger nozzle ring.

Effect of Applying Pressure of High Pressure Diecasting Process Using Salt core (용탕단조 시 저온염코어 적용 가압력의 영향)

  • Lee, Jun-Ho;Moon, J.H.;Lee, Dock-Young
    • Journal of Korea Foundry Society
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    • v.28 no.3
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    • pp.136-140
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    • 2008
  • A new concept of salt core, a melting temperature of which is lower than the solidus temperature of cast alloy, was introduced to produced an integrated casting part having a complicated inner shape or requiring under-cut in high pressure die casting or squeeze casting process. The main goal of this study is to develop a new integrated net-shape forming technology using fusible core of lower melting temperature than that of a casting alloy. This integrated net-shape forming technology would be very successful and cost-effective for producing the integrated products having a complicated inner shape or requiring under-cut. The technology for measuring and evaluating a various property of fusible core such as a thermal conductivity and thermal expansion coefficient, melting temperature was established. Also, the work space can be cleaned without a pollution inducing products.