• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.407-414
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• 1994

Compacts were prepared using the SHS(Self-propagating High-temperature Synthesis) method and nitrided at temperatures range from 145$0^{\circ}C$ to 175$0^{\circ}C$, and pressed at 180$0^{\circ}C$ under N2 atmosphere. The samples were characterized for bulk density, porosity, pore size and distribution, phase composition, microstructure and fracture toughness. Compacts were composed of whiskers, which showed a good candidate for the composite materials. The major phases of the compacts nitrided at 175$0^{\circ}C$ and pressed at 180$0^{\circ}C$ were 15R-sialon with a large aspect ratio.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.987-992
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• 1998

Titanium aluminide intermetallic compound was formed from high purity elemental Ti and A1 foils by selfpropagating, high-temperature synthesis(SHS1 in hot press. Formation of $TiAl_3$ intermetallics at the interface between Ti and Al foil was observed to be controlled by temperature, pressure and heating rate. Especially, the heating rate is the most important role to form intermetallic compound by SHS reaction. According to DTA experiment, the SHS reactions appeared at two different temperatures below and above the melting point of Al. It was also observed that both SHS reaction temperatures increased with increasing the heating rate. After the SHS reaction of alternatively layered 10 Ti and 9 A1 foils at the heating rate of $20^{\circ}C$/min, the $700\mu\textrm{m}$ thick titanium aluminide sheet was formed by heat treatment at $810^{\circ}C$ for 4hours.

• Korean Journal of Materials Research
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• v.7 no.4
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• pp.295-302
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• 1997

금속분말 Fe와 Si에 KNO$_{3}$(Fe+Si)무게비=0.2로 점화촉매 KNO$_{3}$를 혼합하고 50MPa로 성형한 후 점화시키는 비기체연소합성(SHS; Self propagating High temperature Synthesis)법으로 출발 분말을 얻었다. 점화분위기를 공기 및 Ar으로 한 경우 XRD결과에서 특별한 차이가 없었고 두 경우 모두 SiO$_{2}$피크가 검출되었다. 합성된 분말을 성형한 후 119$0^{\circ}C$환원분위기에서 소결하고 포석온도이하에서 열처리하여 반도성 FeSi$_{2}$가 주상인 Fe-Si계 열전재료를 제조하였다. Fe/Si무게비=46/54,44/56 및 42/58시편의 제벡계수는 Si함량이 증가할수록 증가하였다. 점화후의 세척처리를 2단계로 하는 경우 제벡계수의 부호가 변화하여 p-type에서 n-type으로 변화하며 소결밀도가 크게 상승하였다. 조성에 관계없이 공통적으로 발견되는 SiO$_{2}$는 점화시의 분위기보다는 점화촉매에 포함된 K성분이 소결 및 열처리시 산화제로 작용하여 형성되는 것이 확인되었다.

• Journal of the Korean Ceramic Society
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• v.32 no.6
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• pp.659-668
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• 1995

Zirconium carbide was prepared from the mixture of metal zirconium and carbon powders in argon atmosphere by Self-propagating High-temperature Synthesis (SHS) in order to obtain the best carbon source and dilution contents. The most exellent result was obtained in the case that active carbon was added as a starting material, 20~30 wt% dilution content. From thermal profile analysis an apparent activation energy of 118 KJ/mol was calculated. The maximum heating rate achieved during 15 wt% ZrC reaction by product dilution method was approximately 1.54$\times$105 K/s. Coupling this value with the measured wave velocity of 1.026cm/s yielded a maximum thermal gradient fo $1.5\times$105 K/cm. Using the definition of t* and the measured wave velocity, the effective thermal diffusivity, $\alpha$, was calculated to be 0.62$\times$102 $\textrm{cm}^2$/s.

• Korean Journal of Materials Research
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• v.14 no.12
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• pp.885-888
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• 2004

$BaMgAl_{10}O_{17}:Eu^{2+}$ for PDP blue phosphor was synthesized using SHS(Self-propagating High temperature Synthesis) method. While Al metal powder was oxidized in this combustion, $Eu_{2}O_3$ was reduced to Eu2+. Therefore the mole ratio of $Al/Al_{2}O_3$ is one of the most important variable of the reaction. When $Al/Al_{2}O_3$ is 2.5/3.75, it has not only appropriate temperature and reaction velocity, but also excellent luminescent property. The sample synthesized in this system has similar characteristics comparing to sample using conventional solid-state reaction.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.341-348
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• 1995

An analysis of the use of temperature profiles in the determination of the kinetic parameters of combustion synthesis of Ti5Si3 were investigated. From profile analysis, an apparent activation energy of 12KJ/mol was calculated. The Maximum heating rate achieved during 10wt% Ti5Si3 reaction by the product dilution method was approximately $1.5\times$104 K/s. Coupling this value with the measured wave velocity of 7.02 cm/s yields a maximum thermal gradient of 2.14$\times$103 K/cm. The value of tr (=t*) was calculated to be 1.2$\times$10-1 s and the value of td (=tx) was calculated to be 32.89 s. Using the definition of t* and the measured wave velocity, the effective thermal diffusivity, $\alpha$, was calculated to be 0.59$\times$10 $\textrm{cm}^2$/s. From these analysis, the power function, G, was also calculated.

• Composites Research
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• v.16 no.3
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• pp.68-74
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• 2003

In this paper, intermetallic/metal laminated composites have been successfully produced that utilizes SHS reactions between Ni and Al elemental metal foils. The reaction between Ni and Al started from the nucleation and growth of NiA1$_3$ and was followed by the diffusional growth of Ni$_2$A1$_3$ between Ni and NiA1$_3$. The SHS reaction was thermodynamically analyzed through the final volume fraction of the non-reacted Al related with the initial thickness ratio of Ni:Al and prior heat treatment. Thermally aging these 1aminates resulted in formation of a functionally gradient series of intermetallic phases. Microstructure showed that the intermetallic volume percent was 82, 59.5, 40% in the 1:1, 2:1, 4:1 thickness ratio specimen. Main phases of the intermetallic were NiAl and Ni$_3$Al having higher strength at room and high temperatures.

• 연구논문집
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• s.34
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• pp.131-138
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• 2004

Porous silicon nitride ceramics were prepared by Self-propagating High Temperature Synthesis from silicon powder, silicon nitride powder and the pore-forming precursor. The microstructure, porosity and the flexural strength of the porous silicon nitride ceramics were varied according to the Si/$Si_3N_4$ ratio, size and amount of the pore-forming precursors. Some samples exhibited as high flexural strength as $162\pm24$ MPa. The high strength is considered to result from the fine pore size and the strong bonding among the silicon nitrid particles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.451-454
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• 2001

The ionic conductivity of cubic solid solutions in the system $Y_{2}O_{3}-ZrO_{2}$ prepared by SHS was examined. Conductivity-temperature data obtained at $1000^{\circ}C$ in atmosphere of low oxygen partial pressure ($10^{-40}$ atm) for $Y_{2}O_{3}-ZrO_{2}$ cubic solid solutions indicated that these materials could be reduced, the degree of reduction being related to the measuring electric field. At low impressed fields no reduction was observed. Thus, these conductivity data give a transference number for the oxygen ion in $Y_{2}O_{3}-ZrO_{2}$ cubic solid solutions greater than 0.99.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.451-454
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• 2001

The ionic conductivity of cubic solid solutions in the system Y$_2$O$_3$-ZrO$_2$ prepared by SHS was examined. Conductivity-temperature data obtained at 1000$^{\circ}C$ in atmosphere of low oxygen partial pressure (10$\^$-40/ atm) for Y$_2$O$_3$-ZrO$_2$ cubic solid solutions indicated that these materials could be reduced, the degree of reduction being related to the measuring electric field. At low impressed fields no reduction was observed. Thus, these conductivity data give a transference number for the oxygen ion in Y$_2$O$_3$-ZrO$_2$ cubic solid solutions greater than 0.99.