• Title, Summary, Keyword: Reaction layer

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Impact Fracture and Shear Strength Characteristics on Interfacial Reaction Layer of Nb/MoSi2 Laminate Composite

  • Lee, Sang-Pill;Yoon, Han-Ki;Park, Won-Jo
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.3 no.1
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    • pp.35-39
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    • 2000
  • The present study dealt with the relationships among the interfacial shear strength, the thickness of interfacial reaction layer and the impact value of $Nb/MoSi_2$ laminate composites. In addition, the tensile test was conducted to evaluate the fracture strain of $Nb/MoSi_2$ laminate composites. To change the thickness of the reaction layer, $Nb/MoSi_2$ laminate composites alternating sintered MoSi2 layers and Nb foils were fabricated as the parameter of hot press temperature. It has been found that the growth of the reaction layer increases the interfacial shear strength and decreases the impact value by localizing a plastic deformation of Nb foil. There also exist appropriate shear strength and the thickness of the reaction layer, which are capable of maximizing the fracture energy of $Nb/MoSi_2$.

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The Effects of Alloying Elements on the Formation of Interfacial Reaction Layer between Molten Aluminium Alloys and STD61 Tool Steel (알루미늄 합금 용탕/STD61 공구강의 계면 반응층 형성에 미치는 합금원소의 영향)

  • Park, Heung-Il;Park, Ho-Il
    • Journal of Korea Foundry Society
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    • v.25 no.4
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    • pp.161-167
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    • 2005
  • The experiment of hot dip interaction tests was carried out in order to study the formation behavior of interfacial reaction layer between as-received STD61 hot work tool steel and a commercial pure aluminum melt, Al-xwt.%Fe(x=0.2, 0.5, 0.8 and 1.1) alloys melt and Al-xwt.%Si(x=1.0, 4.0, 7.0 and 10.0) alloys melt, respectively. The results show that the reaction layer, over 300 ${\mu}m$ in thickness, is easily formed by the dissolution of silicon from as-received tool steel. When the iron content in the aluminum alloy is higher than 1.1 wt.%, the thickness of reaction layer decreases below 180 ${\mu}m$ by preventing iron dissolution from the tool steel. The silicon dissolved from tool steel acts as a strong promoter on the formation of reaction layer, but the alloyed silicon in molten aluminum alloys acts as an inhibitor on the formation of reaction layer.

A Study on the Direct Synthesis of TaC by Cast-bonding (주조접합법에 의한 TaC 직접합성에 관한 연구)

  • Park, Heung-Il;Lee, Sung-Youl
    • Journal of Korea Foundry Society
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    • v.17 no.4
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    • pp.371-378
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    • 1997
  • The study for direct synthesis of TaC carbide which was a reaction product of tantalum and carbon in the cast iron was performed. Cast iron which has hypo-eutectic composition was cast bonded in the metal mold with tantalum thin sheet of thickness of $100{\mu}m$. The contents of carbon and silicon of cast iron matrix was controlled to have constant carbon equivalent of 3.6. The chracteristics of microstructure and the formation mechanism of TaC carbide in the interfacial reaction layer in the cast iron/tantalum thin sheet heat treated isothermally at $950^{\circ}C$ for various time were examined. TaC carbide reaction layer was grown to the dendritic morphology in the cast iron/tantalum thin sheet interface by the isothermal heat treatment. The composition of TaC carbide was 48.5 at.% $Ti{\sim}48.6$ at.% C-2.8 at.% Fe. The hardness of reaction layer was MHV $1100{\sim}1200$. The thickness of reaction layer linearly increased with increasing the total content of carbon in the cast iron matrix and isothermal heat treating time. The growth constant for TaC reaction layer was proportional to the log[C] of the matrix. The formation mechanism of TaC reaction layer at the interface of cast iron/tantalum thin sheet was proved to be the interfacial reaction.

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Effect of Interfacial Reaction Layer on Mechanical Properties of 3-plyMg/Al/STS Clad-metal (Mg/Al/STS 3층 클래드재의 기계적 특성에 미치는 계면반응층의 영향)

  • Kim, In-Kyu;Song, Jun-Young;Lee, Young Sun;Hong, Sun Ig
    • Korean Journal of Metals and Materials
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    • v.49 no.8
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    • pp.664-670
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    • 2011
  • 3-ply Mg/Al/STS clad-metal was fabricated by the roll bonding process. An interfacial reaction layer was formed at the Mg/Al interface at and above $300^{\circ}C$ whereas no interfacial reaction layer was observed up to $400^{\circ}C$. The effect of the interfacial reaction layer on the mechanical and fracture properties in clad metals after heat treatments were investigated The chemical compositions were analyzed at the Mg/Al interface by an Energy dispersive X-ray analysis (EDX). A tension test was performed to examine the interfacial cracking properties. The Mg layer fractured first, causing a sudden drop of the stress and Al/STS layer continued to deform until the final fracture. Periodic cracks and crack propagation was observed at the reaction layer between Mg and Al.

High speed deposition technique of YSZ film for the superconducting tape (고온초전도테이프 제작을 위한 YSZ 박막의 고속증착방법)

  • Kim Ho-Sup;Shi Dongqui;Chung Jun-Ki;Ko Rock-Kil;Ha Hong-Soo;Song Kyu-Jeong;Youm Do-Jun;Park Chan
    • Progress in Superconductivity and Cryogenics
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    • v.6 no.3
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    • pp.27-32
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    • 2004
  • High temperature superconducting coated conductor has a structure of /< superconducting layer>//. The buffer layer consists of multi layer, and the architecture most widely used in RABiTS approach is CeO$_2$(cap layer)/YSZ(diffusion barrier layer)/CeO$_2$(seed layer). Evaporation technique is used for the CeO$_2$ layer and DC reactive sputtering technique is used for the YSZ layer, A chamber was set up specially for DC reactive sputtering, Detailed features are as following. A separator divided the chamber into two halves a sputtering chamber and a reaction chamber. The argon gas for sputtering target elements flows out of the cap of sputtering gun, and water vapor for reaction with depositing species spouts near the substrate. Turbo pump is connected with reaction chamber. High speed deposition of YSZ film could be achieved in the chamber. Detailed deposition conditions (temperature and partial pressure of reaction gas) were investigated for the rapid growth of high quality YSZ film.

A Study on Bumping of Micoro-Solder for Optical Packaging and Reaction at Solder/UBM interface (광패키징용 마이크로 솔더범프의 형성과 Contact Pad용 UBM간의 계면 반응 특성에 관한 연구)

  • Park, Jong-Hwan;Lee, Jong-Hyun;Kim, Yong-Seog
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.332-336
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    • 2001
  • In this study, the reaction at UBM(Under Bump Metallurgy) and solder interface was investigated. The UBM employed in conventional optical packages, Au/Pt/Ti layer, were found to dissolve into molten Au-Sn eutectic solder during reflow soldering. Therefore, the reaction with different diffusion barrier layer such as Fe, Co, Ni were investigated to replace the conventional Pt layer. The reaction behavior was investigated by reflowing the solder on the pad of the metals defined by Cr layer for 1, 2, 3, 4, and 5 minutes at $330^{\circ}C$. Among the metals, Co was found to be most suitable for the diffusion barrier layer as the wettability with the solder was reasonable and the reaction rate of intermetallic formation at the interface is relatively slow.

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A Study on Bumping of Micro-Solder for Optical Packaging and Reaction at Solder/UBM interface (광패키징용 마이크로 솔더범프의 형성과 Contact Pad용 UBM간의 계면 반응 특성에 관한 연구)

  • 박종환;이종현;김용석
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.332-336
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    • 2001
  • In this study, the reaction at UBM(Under Bump Metallurgy) and solder interface was investigated. The UBM employed in conventional optical packages, Au/Pt/Ti layer, were found to dissolve into molten Au-Sn eutectic solder during reflow soldering. Therefore, the reaction with different diffusion barrier layer such as Fe, Co, Ni were investigated to replace the conventional R layer. The reaction behavior was investigated by reflowing the solder on the pad of the metals defined by Cr layer for 1, 2, 3, 4, and 5 minutes at 330$^{\circ}C$. Among the metals, Co was found to be most suitable for the diffusion barrier layer as the wettability with the solder was reasonable and the reaction rate of intermetallic formation at the interface is relatively slow.

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Joining of AIN Ceramics to Metals: Effect of Reactions and Microstructural Developments in the Bonded Interface on the Joint Strength (질화알루미늄과 금속간 계면접합에 관한 연구: 계면반응과 미세구조 형성이 접합체 강도에 미치는 영향)

  • 박성계
    • Journal of Korean Powder Metallurgy Institute
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    • v.4 no.3
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    • pp.196-204
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    • 1997
  • Joining of AIN ceramics to W and Cu by active-metal brazing method was tried with use of (Ag-Cu)-Ti alloy as insert-metal. Joints were produced under various conditions of temperature, holding time and Ti-content in (Ag-Cu) alloy Reaction and microstructural development in bonded interface were investigated through observation and analysis by SEM/EDS, EPMA and XRD. Joint strengths were measured by shear test. Bonded interface consists of two layers: an insert-metal layer of eutectic Ag- and Cu-rich phases and a reaction layer of TiN. Thickness of reaction layer increases with bonding temperature, holding time and Ti-content of insert-metal. It was confirmed that the growth of reaction layer is a diffusion-controlled process. Activation energy for this process was 260 KJ/mol which is lower than that for N diffusion in TiN. Maximum shear strength of 108 MPa and 72 MPa were obtained for AIN/W and AIN/Cu joints, respectively. Relationship between processing variables, joint strength and thickness of reaction layer was also explained.

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Intramolecular Esterification by Lipase Powder in Microaqueous Cycohexane (미소 수용 Cyclohexange 중에서 분말 Lipase에 의한 분자내 에스테르화반응)

  • 이민규;감삼규
    • Journal of Life Science
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    • v.5 no.4
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    • pp.155-161
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    • 1995
  • The effects of substrate concentration, enzyme concentration, reaction temperature, and water content were investigated in intramolecular esterification. This study used cyclohexane as organic solvent, power lipase as enzyme, and benzyl alcohol and octanoic acid as substrate. The initial reaction rate was found to be proportional to enzyme concentration; followed Michaelis-Menten equation for octanoic acid; and was inhibited by benzyl alcohol . The observed initial reaction rate first increased, then decreased with increasing reaction temperature, giving rise to the maximum rate at 20$\circ$. The drop in the reaction rate at higher temperature was to partition equilibrium change of substrate between organic solvent and hydration layer of enzyme molecule in addition to the deactivation by enzyme denaturation. Water layer surrounding enzyme molecule seemed to activate in organic solvent and the realistic reaction was done in the water layer. In the enzymatic reaction in organic solvent, the initial reaction rate was influenced by partition quilibrium of substrate, so the optimum condition of substrate concentration, enzyme concentration, reaction temperature, and water content would give a good design tool.

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Electrochemical Effectiveness Factors for Butler-Volmer Reaction Kinetics in Active Electrode Layers of Solid Oxide Fuel Cells

  • Nam, Jin Hyun
    • Journal of Electrochemical Science and Technology
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    • v.8 no.4
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    • pp.344-355
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    • 2017
  • In this study, a numerical approach is adopted to investigate the effectiveness factors for distributed electrochemical reactions in thin active reaction layers of solid oxide fuel cells (SOFCs), taking into account the Butler-Volmer reaction kinetics. The mathematical equations for the electrochemical reaction and charge conduction process were formulated by assuming that the active reaction layer has a small thickness, homogeneous microstructure, and high effective electronic conductivity. The effectiveness factor is defined as the ratio of the actual reaction rate (or equivalently, current generation rate) in the active reaction layer to the nominal reaction rate. From extensive numerical calculations, the effectiveness factors were obtained for various charge transfer coefficients of 0.3-0.8. These effectiveness data were then fitted to simple correlation equations, and the resulting correlation coefficients are presented along with estimated magnitude of error.