• Korean Journal of Materials Research
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• v.10 no.5
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• pp.343-349
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• 2000

Fabrication of various carbide fibers from carbon fibers and elementary powders of Ti, Zr, Nb, Zi, W, B, and Mo by self-propagating high temperature synthesis was attempted. It was found the almost pure phase of TiC, ZrC, NbC, SiC, $B_4$C, and $Mo_2$C carbides were successfully produced. The three types of morphologies were ob-served, TiC, ZrC, NbC, and $B_4$C had a hollow-type fibrous shape. SiC had fiber shape consisting of smaller particles and fine whiskers. WC and $Mo_2$C had non-fibrous shapes. The reason for the different morphologies was explained. The formation mechanism of hollow fibers was suggested.

• Korean Journal of Materials Research
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• v.6 no.12
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• pp.1199-1212
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• 1996

본 연구는 주조성, 내압성, 내열성 등이 우수하여 군용 및 민수용 기계소재로 이용되고 있는 AI-Si-Mg계 AC4C 합금에 세라믹(AI2O3, AI2O3-TiC)을 강화시키는 복합재료제조에 관한 기초연구의 일환으로 수행하였다. 연구내용은 세라믹 강화재의 젖음성을 높이기 위하여 수소환원법에 의한 AI2O3입자의 Ni 피복과 기존의 프리폰 제조방법보다 간단하고 경제적인 자전연소합성법에 의해 AI2O3-TiC 다공성 pellet을 제조하여, 이들 강화재와 AC4C 기지금속을 이용하여 고대-compocasting 및 squeeze casting법으로 복합재료를 제조하고 미세조직, 계면생성물, 기계적 성질, 내마멸성 등의 특성을 조사하였다. 고대-compocasting법에 의해 제조된 AI2O3Ni 입자 강화 복합재료에서 강화재들은 응집체로 존재하지 않고 비교적 균일하게 분산되었고 AI2O3-TiC 강화재를 이용하여 squeeze casting으로 가압주조 하므로써 기지금속과 강화재의 젖음성이 향상되었다.

• 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.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.152-156
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• 2007

Tungsten carbide powder was synthesized by SHS (self-propagating high-temperature synthesis). Except $WO_{3}$, each concentration of raw material ($WO_{3},\;Mg,\;NaCl,\;Na_{2}CO_{3},\;C$) was investigated. Final product was characterized by XRD and SEM. X-ray data demonstrated that the $NaCl+Na_{2}CO_{3}$ combined mixture has superiority in the WC formation process. Single phase and submicrometer WC powder was synthesized at the temperature below $1600^{\circ}C$. The role of sodium salts in combustion process was discussed, and chemical mechanism of WC formation was proposed. WC powder prepared by salt-assisted combustion synthesis has a size $0.2{\sim}3\;{\mu}m$ and low agglomeration degree.

• Korean Journal of Materials Research
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• v.5 no.3
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• pp.345-356
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• 1995

본 연구에서는 TiAl 금속간 화합물을 자전 고온 반응법을 이용하여 제조시 반응과정을 열시차 분석 방법으로 분석하였다. 합금 조성은 Ti-45at% Al, 53at%Al, 알루미늄 분말 크기, 승온 속도, 성형 밀도 등을 변화시켜 이들이 반응 과정에 미치는 영향을 관찰하였다. 분말이 미세할수록, 승온속도가 느릴수록, 성형 밀도가 낮을수록 반응 점화 온도 및 연소 온도가 감소하였으며, 고상 Ti와 고상 Al간의 반응정도가 증가하는 것이 관찰되었다. 고상 Ti와 고상 Al간의 반응에서 생성되는 것은 XRD 분석 결과 Ti$Al_{3}$상으로 확인되었다. 이에 비하여 반응 점화 온도가 알루미늄의 용융 온도보가 높을 경우에는 생성되는 상이 $Ti_{3}$Al, TiAl상으로 확인되었다. 이러한 상의 생성 원인에 대하여 확산 계수 및 알루미늄의 용해도등의 요인으로 설명하였다.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.338-343
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• 2009

The purpose of this study is to make the tantalum powder for solid electrolyte capacitor with SHS (self-propagating high-temperature synthesis) process. Raw materials for manufacturing Ta powder were used $Ta_{2}O_{5}$, Mg and NaCl. While progressing SHS process, $Ta_{2}O_{5}$ powder was reduced by Mg powder. The combustion temperature and velocity were easily controled by the varying mole ratio of NaCl, Mg and initial reaction pressure. In the case of only using NaCl as an inorganic agent, the shape is unagglomerated and has high surface area. whereas we were given the powder which has good net structure by the addition of excessive Mg as a diluent.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.388-394
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• 2004

LiCoO$_2$ as the cathode activity material for lithium secondary battery was prepared from a homogeneously mixed powder of LiNO$_3$/Co by SHS process under argon gas. The characteristics of powder including electrochemical properties were investigated according to various reaction conditions. The reaction temperature/velocity and the size of LiCoO$_2$ were controlled by Li/Co molar ratio and a cooling rate of the specimen, respectively. The maximum discharge capacity was 145 mAh/g on 1.05 Li/Co molar ratio and the relatively stable cycling characteristic with 6.4% of capacity fading was obtained after 10th charging-discharging test.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.907-914
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• 2004

The nitridation mechanism of Si by SHS at $Si-NaCl-NH_{4}Cl-NaN_3$ system was investigated in this work. It was revealed that NaCl as a diluent was helpful to the perfect nitridation reaction by retarding the growth of Si particle resulted from the melting of Si at the initial stage of the nitridation reaction. And $NH_{4}Cl\;and\;NaN_3$ formed NaCl through decomposition and combination, and the preheating of pellet was helpful to the nitridation reaction in this process. The main nitridation mechanism of this system was liquid-gas reaction. The optimum porosity of the pellet for the nitridation of ${\alpha}-Si_{3}N_4$ was $67-69\%$.

• 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.

• Journal of the Korean Ceramic Society
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• v.43 no.7 s.290
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• pp.427-432
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• 2006

The preparation of SiC powder by SHS in the system of $SiO_2-Mg-C$ was investigated in this study. The effects of various processing parameters such as the initial pressure of inert gas in reactor, the content of Mg and C in mixture and the size of $SiO_2$ particles on the synthesis of SiC by SHS methode were investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5 atm, and as the pressure increased, and the concentration of unreacted Mg decreased. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure SiC was $SiO_2+2.5Mg+1.2C$. SiC powder synthesized in this condition had a mixture of ${\alpha}-SiC\;and\;{\beta}-SiC$ with an irregular shape and the particle size of $0.5{\sim}0.8{\mu}m$.