• Title/Summary/Keyword: SHS propagation

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A Study on the Behavior of Combustion Wave Propagation and the Structure of Porous TiNi Body during Self-propagating High-temperature Synthesis Process

  • Kim, Ji-Soon;Gjuntera, Victor E.;Kim, Jin-Chun;Kwon, Young-Soon
    • Journal of Powder Materials
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    • v.17 no.1
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    • pp.29-35
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    • 2010
  • We produced cylindrical porous TiNi bodies by Self-propagating High-temperature Synthesis (SHS) process, varying the heating schedule prior to ignition of a loose preform compact made from (Ti+Ni) powder mixture. To investigate the effect of the heating schedule on the behaviour of combustion wave propagation and the structure of porous TiNi shape-memory alloy (SMA) body, change of temperature in the compact during SHS process was measured as a function of time and used for determining combustion temperature and combustion wave velocity. Microstructure of produced porous TiNi SMA body was observed and the results were discussed with the combustion characteristics. From the results it was concluded that the final average pore size could be controlled either by the combustion wave velocity or by the average temperature of the preform compact prior to ignition.

Peculiarities of SHS and Solid State Synthesis of ReBa2Cu3O7-x Materials

  • Soh, Deawha;Natalya, Korobova
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.3
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    • pp.275-280
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    • 2002
  • The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid-stave chase synthesis for production of high temperature superconductor materials were discussed. Oxide superconductors with general formula of $ReBa_2Cu_3O_{7-x}$ (Re=Y, Sm) haute been made by using barium oxide initial powder instead of traditional barium carbonate. Phenomena observed during the grinding of the reactants mixture are presented. Mechano-chemical activation - as a pre-treatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.

Preparation of $Al_2O_3-SiC$ Composite Powder by SHS Method (SHS법에 의한 $Al_2O_3-SiC$ 복합분말의 합성)

  • 이형민;이홍림;이형직
    • Journal of the Korean Ceramic Society
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    • v.32 no.1
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    • pp.11-16
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    • 1995
  • High reaction heat evolved from the oxidation of Al was used to synthesize SiC, which might be difficult to be formed by SHS. Al2O3-SiC composite powder was easily manufactured using KNO3 as an ignition and reaction catalyst. Unreacted Si and C were observed after reaction dependent upon the composition of starting powders, reaction atmosphere and relative densities of compacted bodies. The unreacted carbon could be removed by calcining at $600^{\circ}C$ and the remaining Si could be removed by dissolving in NaOH solution. The final powder particles were smaller than 1${\mu}{\textrm}{m}$ in size.

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A Study on Synthesis and Characterization of $Ti_xZr_{1-x}C$ Solid-Solution by Self-propagation High Temperature Synthesis Method (SHS법에 의한 $Ti_xZr_{1-x}C$ 고용체의 합성 및 특성 연구)

  • 이형복;오유근;이성민
    • Journal of the Korean Ceramic Society
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    • v.34 no.7
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    • pp.731-737
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    • 1997
  • TixZr1-xC(0$0^{\circ}C$, 5.1 mm/sec respectively. The relative density, three point flexural strength, and the hardness of composites, which was sintered at 190$0^{\circ}C$ for 60 min by using hot-pressing under a pressure of 30 MPa, were 99%, 525 MPa and 24 GPa respectively.

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Preparation of B4C-Al2O3 Composite Powder by Self-propagation High-temperature Synthesis(SHS) Process under High Pressure (고압 자전 고온반응 합성법에 의한 B4C-Al2O3복합분말 제조)

  • 임경란;강덕일;김창삼
    • Journal of the Korean Ceramic Society
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    • v.40 no.1
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    • pp.18-23
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    • 2003
  • Composite powder of$B_4C-A1_2O_3$was prepared from a mixed powder of$B_2O_3/A1/C$by SHS under argon pressure instead of using a chemical furnace. A mixture of$B_2O_3,$Al and C powder (equivalent amounts to the reaction,$2B_2O_3+4A1+C=B_4C+2A1_2O_3)$was ball milled for 2 h. The mixed powder was placed in a SHS reactor and filled with 10 atm of argon gas and ignited. The inner and outer products were the same by XRD analysis. It was consisted of a composite powder of$B_4C-A1_2O_3$without $AlB_{12}/C_2$which was always produced using a chemical furnace. The composite powder was about$60~100{mu}m$size which was composed of crystalline particles of about 0.3~l${mu}m$size. But when 15 atm of argon was employed, partial sintering took place to give rise hard composite powder of$15~25{mu}m$$B_4C$with $0.1~0.2{mu}m$$A1_2O_3.$

AlN preparation by Self-propagation High-temperature Synthesis (SHS) in Al-N2 and Al-N2-AIN system (Al-N2와 Al-N2-AlN계에서 고온자전연소법에 의한 AlN 합성)

  • 이재령;이익규;안종관;김동진;안양규;정헌생
    • Journal of Powder Materials
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    • v.11 no.4
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    • pp.294-300
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    • 2004
  • This study for preparation of aluminum nitride (AlN) with high purity was carried out by self-propagating high-temperature synthesis method in two different systems, $Al-N_{2}$ and $Al-N_{2}$-AlN, with the change of nitrogen gas pressure and dilution factor. On the occasion of $Al-N_{2}$ system, unreacted aluminum was detected in the product in spite of high nitrogen pressure, 10 MPa, This may be caused by obstructing nitrogen gas flow to inner part of molten and agglomerate of aluminum, formed in pre-heating zone. In $Al-N_{2}$-AlN system, AlN with a purity of 95% or ever can be prepared in the condition of $f_{Dil}\geq0.5$, $P_{N_{2}}\geq$ 1 MPa, and the purity can be elevated to 98% over in the condition of $f_{Dil}$ = 0.7 and $P_{N_{2}}$ = 10 MPa.

Preparation of TaC Powder from the Waste of Ta powder Fabrication Process for Capacitor (Capacitor용 Ta분말 제조공정 Waste Ta를 이용한 TaC분말 제조)

  • Park Je-Shin;Suh Chang-Youl;Yaon Jae-Sik;Bae In-Sung;Park Hyeoung-Ho
    • Resources Recycling
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    • v.12 no.4
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    • pp.51-57
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    • 2003
  • Using the wastes of Ta powder fabrication process for capacitor, TaC powder was synthesized by SHS method. In previous to synthesis, the waste Ta was needed of milling and deoxidization treatments for active reaction and prevention of oxidation. In SHS reaction, it was found that the TaC single phase was obtained in composition of 5~6wt.%C. The reaction temperature was affected by the compaction pressure of the specimens, exhibiting the maximum values at 1600psi, respectively.

Combustion Synthesis of YAG:Ce Phosphor with Teflon (Teflon을 이용한 YAG:Ce 형광체 합성)

  • Yeon, Jung Woon;Won, Chang Whan;Won, Hyung Il;Nersisyan, H.H.
    • Korean Journal of Metals and Materials
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    • v.50 no.6
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    • pp.439-443
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    • 2012
  • YAG:Ce phosphor were prepared in a self-propagating high-temperature synthesis (SHS) using a $1.5Y_2O_3+2.5Al_2O_3+0.116CeO_2+3.0KClO_3+kCO(NH_2)_2+m(C_2F_4)_n$ precursor mixture. The heat for the combustion propagation was provided by the reaction of a $KClO_3+CO(NH_2)_2+(C_2F_4)n$ mixture. Pure-phase YAG phosphor was synthesized at the combustion temperature of $1210^{\circ}C$ from k=3.6 mole and m=0.3 mole. The as-prepared YAG:Ce phosphor had a particle size of $2-10{\mu}m$. The addition of Teflon to the precursor mixture increased the YAG particle size and its luminescent intensity. The emission peak of the YAG phosphor was blue-shifted with an increase of Teflon concentration.

Effect of Diluent Size on Aluminum Nitride Prepared by Using Self-Propagating High-Temperature Synthesis Process (희석제 입도가 고온자전연소법에 의한 질화알루미늄 합성에 미치는 영향)

  • Lee, Jae-Ryeong;Lee, Ik-Kyu;Shin, Hee-Young;Chung, Hun-Saeng
    • Journal of the Korean Ceramic Society
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    • v.42 no.1
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    • pp.69-75
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    • 2005
  • To investigate the morphological effect on synthesis of aluminum nitride by SHS Process, two type of Al Powder (granular and flacky shape) with the mean size of 34 $\mu$m and the diluent AIN powders of four different mean sizes.0.12, 9.7, 39.3, 50.5 $\mu$m, were used to prepare green compact. The packing density was fixed to $35 TD\%. The initial pressure of $N_{2}$ and diluent fraction was varied in the range of $1\~10 MPa,\;0.4\~0.7$, respectively. AlN with high purity of $98\% or over and large particle size of about several tens fm can be synthesized by SHS reaction as a consequence of adjusting particle size of AlN dilutent similarly to that of Al reactant. This may be caused by improvement of $N_{2}$ gas permeation to compact after passing the propagation wave. In the case of flaky-shape aluminum used as reactant, instead of granular Al-powder, unstable combustion would be occurred. As the result, irregular propagation of combustion wave and falling-off of maximum temperature would be observed during the reaction.