• Title/Summary/Keyword: Self-propagating high-temperature synthesis

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Study on Synthesis and Mechanical Properties of (B.Si)C Composite by Self Propagating High Temperature Synthesis Chemical Furnace (SHS 화학로에 의한 (B.Si)C 복합체의 합성 및 기계적 특성에 관한 연구)

  • 이형복;조덕호;이재원
    • Journal of the Korean Ceramic Society
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    • v.32 no.4
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    • pp.413-418
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    • 1995
  • The (B.Si)C composite was prepared form the mixture of metal boron, silicon, and carbon powders in Ar atmosphere by Self-propagating High-temperature Synthesis Chemical Furnace. The characterization of synthesized power and sintered body were investigated. The microstructure of sintered body suggested that SiC boundary was made between B4C grains. The most excellent mechanical properties, the relative density of 95% oftheoretical value, 3 point flexural strength of 360MPa, and fracture toughness of 3.6MN/m3/2 could be obtained in 80wt% B4C-20 wt% SiC composite were obtained.

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Formation of Fe Aluminide Multilayered Sheet by Self-Propagating High-Temperature Synthesis and Diffusion Annealing (고온자전반응합성과 확산 열처리를 이용한 FeAl계 금속간화합물 복합판재의 제조)

  • Kim, Yeon-Wook;Yun, Young-Mok
    • Korean Journal of Materials Research
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    • v.18 no.3
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    • pp.153-158
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    • 2008
  • Fe-aluminides have the potential to replace many types of stainless steels that are currently used in structural applications. Once commercialized, it is expected that they will be twice as strong as stainless steels with higher corrosion resistance at high temperatures, while their average production cost will be approximately 10% of that of stainless steels. Self-propagating, high-temperature Synthesis (SHS) has been used to produce intermetallic and ceramic compounds from reactions between elemental constituents. The driving force for the SHS is the high thermodynamic stability during the formation of the intermetallic compound. Therefore, the advantages of the SHS method include a higher purity of the products, low energy requirements and the relative simplicity of the process. In this work, a Fe-aluminide intermetallic compound was formed from high-purity elemental Fe and Al foils via a SHS reaction in a hot press. The formation of iron aluminides at the interface between the Fe and Al foil was observed to be controlled by the temperature, pressure and heating rate. Particularly, the heating rate plays the most important role in the formation of the intermetallic compound during the SHS reaction. According to a DSC analysis, a SHS reaction appeared at two different temperatures below and above the metaling point of Al. It was also observed that the SHS reaction temperatures increased as the heating rate increased. A fully dense, well-bonded intermetallic composite sheet with a thickness of $700\;{\mu}m$ was formed by a heat treatment at $665^{\circ}C$ for 15 hours after a SHS reaction of alternatively layered 10 Fe and 9 Al foils. The phases and microstructures of the intermetallic composite sheets were confirmed by EPMA and XRD analyses.

Study on Sintering Properties of $TiB_2-TiC$ Composite by Self-Propagating High Temperature Synthesis Method (SHS법에 의한 $TiB_2-TiC$ 복합체의 소결특성에 관한 연구)

  • 이형복;조덕호;장준원
    • Journal of the Korean Ceramic Society
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    • v.29 no.7
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    • pp.577-585
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    • 1992
  • TiB2 and TiC were prepared from the mixture of metal titanium, boron and graphite powders in Argon atmosphere by Self-propagating High-temperature Synthesis method. The sintered properties of TiB2-TiC composite as a function of TiC content and sintering temperature were investigated in TiB2 matrix. The sintered properties were the most excellent at 10 wt% TiC content in TiB2-TiC composite. The relative density, M.O.R strength, hardness and fracture toughness of TiB2-10 wt% TiC composite sintered at 190$0^{\circ}C$ for 90 min by hot-pressing under the pressure of 30 MPa were 98.6%, 634 MPa, 2128.1 kg/$\textrm{mm}^2$ and 4.09 MN/m3/2, respectively.

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High-Temperature Oxidation of MoSi2 Heating Elements (이규화몰리브덴 고온발열체의 고온산화거동)

  • Seo, Chang-Yeol;Jang, Dae-Ga;Sim, Geon-Ju;Jo, Deok-Ho;Kim, Won-Baek
    • Korean Journal of Materials Research
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    • v.6 no.1
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    • pp.57-66
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    • 1996
  • MoSi2 heating elements were fabricated by sintering of MoSi2 powders which were synthesized through SHS(Self-propagating high-temperature synthesis). Their high-temperature oxidation behavior in air through SHS(Self-propagating high-temperature synthesis). Their high-temperature oxidation behavior on air at 1000-1600$^{\circ}C$ was investigated through a high-temperature X-ray diffractomer and isothermal heating in a muffle furnace. The thermal expansion of MoSi2 and SiO2 was studied by measuring their lattice parameters on heating. The linear expansion coeffcient of MoSi2 along c-axis was about 1.5 times larger than that along a-axis showing a strong thermal anisotropy. Few $\mu\textrm{m}$-thick Mo5Si3 layer was found beneath SiO2 layer suggesting that The major reaction products would be SiO2 and Mo5Si3. The Si-rich bentonite resulted in the faster growth of MoSi2 grains probably by enhancing the mass transport when they are melted during high-temperature oxidation.

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Fabrication Process of Laminated Composites by Self-propagating High-temperature Synthesis Reaction (자전고온반응에 의한 적층복합재료의 제조공정)

  • 김희연;정동석;홍순형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.05a
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    • pp.155-158
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    • 2002
  • Fabrication process of metal/intermetallic laminated composites by using self-propagating high temperature synthesis(SHS) reactions between Ni and Al elemental metal foils have been investigated. Al foils were sandwiched between Ni foils and heated in a vacuum hot press to the melting point of aluminium. SHS reaction kinetics was thermodynamically analyzed through the final volume fraction of the unreacted Al related with the initial thickness ratio of Ni:Al and diffusion bonding stage before SHS reaction. Thermal aging of laminated composites resulted in the formation of functionally gradient series of intermetallic phases. Microstructure showed that the main phases of intermetallics were NiAl and $Ni_3Al$ having higher strength at room and high temperatures. The volume fractions of intermetallic phases were measured as 82.4, 58.6, 38.4% in 1:1, 2:1, 4:1 initial thickness ratio of Ni:Al.

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