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가미다;하국현;김병기
- Journal of Powder Materials
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- v.10 no.1
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- pp.1-5
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- 2003
Nano-sized WC powders were synthesized by vapor phase reaction using the precusor of tungsten ethoxide under helium and hydrogen atmosphere. The phases of the powder were varied with reaction Bone and gas flow rate. The powder size was about 30nm in diameter, and the tungsten carbide powder was coated by carbon layer. The synthesis of nano-sized WC powders was promoted as the hydrogen gas flow rate became higher. Inversely, tungsten oxide was formed by increasing the flow rate of helium gas. The synthesized powders were analyzed by XRD, FE-SEM, carbon analyzer etc.
https://doi.org/10.4150/KPMI.2003.10.1.001 인용 PDF KSCI

안영수;한문희;김종오
- Journal of the Korean Ceramic Society
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- v.33 no.6
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- pp.693-699
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- 1996
YIG precursor powder was obtained by homogeneous precipitation in chloride salt solution by thermal decom-position of urea. It was found that ferric ions precipitated prior to yttrium ions. The precipitate was minute and spherical in shape. The precipitate formed consisted of the mixture of amorphous and ferric oxyhydroxide. Crystallization of YIG was proceeded by solid state reaction of intermediate YFeO3 and Fe2O3 in the temperature range of 85$0^{\circ}C$ to 140$0^{\circ}C$. Single phase of YIG was obtained by heat-treatment of the powder at 140$0^{\circ}C$ for 6 hrs in air. The powder calcined was molded into pellets and sintered in air. The maximum density of 4,92 g/cm3(95.1% of theoretical density) was obtainable for the pellet sintered at 145$0^{\circ}C$ using the powder calcined at 90$0^{\circ}C$.
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현성호;김정환;허윤행
- Journal of environmental and Sanitary engineering
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- v.13 no.1
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- pp.147-156
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- 1998
A synthesis process for PZT powder using $NH_{3}$ gas as a precipitator in a bubble column reactor was experimentally successful in develope a production process of piezoelectric ceramic PZT powder. Also as a reaction by coprecipitation, the crystalized PZT ceramic powder at the condition of over pH 9 could be attained. The time needed for reaction on the condition of $NH_{3}$ gas flow rate = 0.5 1/min, Ar gas flow rate = 2.0 1/min. Feed flow rate = 2.33 ml/sec was less than five minutes, so it could synthesize PZT powder for such a few moments. And the synthesized PZT powder was $0.17{\mu}m$ in diameter on an average.
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Han, Jae-Ho;Park, Sang-Whan;Kim, Young-Do
- Proceedings of the Korean Powder Metallurgy Institute Conference
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- 2006.09b
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- pp.868-869
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- 2006
[ $Cr_2AlC$ ] was synthesized by a reactive hot pressing of $CrC_x(x=0.5)$ and Al powder mixture used as starting materials at the temperature range of $1200^{\circ}C{\sim}1400^{\circ}C$ under 25 MPa in Ar atmosphere. Fully dense $Cr_2AlC$ with high purity was synthesized by hot pressing $CrC_x$ and Al powder mixture at the temperature as low as $1200^{\circ}C$. The average grain size of synthesized bulk $Cr_2AlC$ was varied in the range of $10-100{\mu}m$ depending on hot pressing temperatures. The maximum flexural strength of synthesized bulk $Cr_2AlC$ exceeded 600 MPa.
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Seong, Ki-Hun;Lee, Jai-Sung
- Proceedings of the Korean Powder Metallurgy Institute Conference
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- 2006.09a
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- pp.482-483
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- 2006
Synthesis of iron nanopowder by room-temperature electrochemical reduction process of ${\alpha}-Fe_2O_3$ nanopowder was investigated in terms of phase evolution and microstructure. As process variables, reduction time and applied voltage were changed in the range of $1{\sim}20$ h and $30{\sim}40$ V, respectively. From XRD analyses, it was found that volume of Fe phase increased with increasing reduction time and applied voltage, respectively. The crystallite size of Fe phase in all powder samples was less than 30 nm, implying that particle growth was inhibited by the reaction at room temperature. Based on the distinct equilibrium shape of crystalline particle, phase composition of nanoparticles was identified by TEM observation.
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