• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.528-534
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• 2004

Using the nano Fe powders having 50 nm in diameter, Fe compact bodies were fabricated by injec-tion molding process. The relationship between microstructure and material properties depending on the volume ratio of powder/binder and sintering temperature were characterized by SEM, TEM techniques. In the compact body with the volume percentage ratio of 45(Fe powder) : 55(binder), which was sintered at $700^{\circ}C,$ the relative density was about $97{\%},$ and the values of volume shrinkage and hardness were about $66.3{\%}$ and 242.0 Hv, respec-tively. Using the composition of 50(Fe powder) : 50(binder) and sintered at $700^{\circ}C,$ the values of relative density, volume shrinkage and hardness of Fe sintered bodies were $73.3{\%},\;47.6{\%}$ and 152.8 Hv, respectively. They showed brittle fracture mode due to the porous and fine microstructure.

• Journal of the Korean Ceramic Society
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• v.32 no.12
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• pp.1383-1391
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• 1995

Hexagonal $\delta$-FeOOH was coated with Ba-Sol, which was produced by hydrolizing Ba(OC2H5)2, Ba-Sol coated $\delta$-FeOOH spread on a stainless plate, dried at 8$0^{\circ}C$ and then heat-treated. In this way, Ba-ferrite fine particles were produced. although there was a difference in a degree of hydrolysis of Ba(OC2H5)2, crystalline phase of Ba-ferrite appeared around 617$^{\circ}C$, and Ba-ferrite single phase was obtained after heat treatment at 80$0^{\circ}C$ for 2 hr. When Ba-ferrite was made from Ba-Sol coated $\delta$-FeOOH, $\delta$-FeOOH was thermally decomposed to $\alpha$-Fe2O3 at $700^{\circ}C$, producing a porous structure which was observed by TEM photographs. But the porous structure was not observed at 80$0^{\circ}C$. Ba-ferrite, heat-treated at 80$0^{\circ}C$ for 2 hr, had mean particle size of 1000$\AA$, lattice parameter of a0=5.889243 $\AA$ and c0=23.214502 $\AA$, a saturation magnetization ($\sigma$8) of 45.3 emu/g and a coercive force (Hc) of 5200Oe.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.237-242
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• 2006

$Fe_3O_4$ and $CoFe_2O_4$ magnetic nanoparticles have been synthesized successfully in aqueous solution and coated with oleic acid. The solid and organic solution of the synthesized nanoparticles was obtained. Self-assembled monolayer films were formed using organic solution of these nanoparticles. The crystal sizes determined by Debye-Scherre equation with XRD data were found close to the particle sizes calculated from TEM images, and this indicates that the synthesized particles are nanocrystalline. Especially, EDS, ED, FT-IR, TGA/DTA and DSC were used to characterize the nanoparticles and the oleic acid adsorption, and it was found that oleic acid molecule on the $Fe_3O_4$ nanoparticle is a bilayer adsorption, while that on $CoFe_2O_4$ nanoparticle is single layer adsorption. The superparamagnetic behavior of the nanoparticles was documented by the hysteresis loop measured at 300 K.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.433-438
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• 2010

Fe-carbon/$TiO_2$ composites were prepared by a sol-gel method using AC, ACF, CNT and $C_{60}$ as carbon precursors and were characterized by means of BET surface area, X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The activity of the prepared photocatalysts was investigated by degradation reaction of methylene blue (MB) irradiated with UV lamp. Effects of different carbon sources and irradiation time on photocatalytic activity were also investigated. The results showed that the photocatalytic activity of the Fe-carbon/$TiO_2$ composites was much higher than that of pristine $TiO_2$ and Fe/$TiO_2$ composites. The prominent photocatalytic activity of Fecarbon/$TiO_2$ composites could be attributed to both the effects of photo-adsorption and electron transfer by carbon substrate. In addition, the higher photocatalytic activity of Fe-carbon/$TiO_2$ composites can be compared with that of carbon/$TiO_2$ and Fe /$TiO_2$ composites due to cooperative effects between Fe and carbon.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.341-348
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• 2019

This paper reports the microstructure and electrochemical properties of Si-Al-Fe ternary amorphous alloys prepared by rapid solidification as an anode for lithium secondary batteries. The microstructure was analyzed using XRD and HR-TEM with EDS mapping. In accordance with DSC analysis, annealing was performed to crystallize the active nano-Si in the amorphous alloy. Thus, nano-Si forms (~80 nm) embedded in the matrix alloy, such as $Fe_2Al_3Si_3$, $FeSi_2$, and $Fe_{0.42}Si_{2.67}$, were successfully synthesized. The electrode based on the Si-Al-Fe ternary alloy delivered an initial discharge capacity of approximately $700mAh^{g-1}$, and exhibited a high Coulombic efficiency of 99.0~99.6% from the $2^{nd}$ to $70^{th}$ cycles.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.240.1-240.1
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• 2011

본 연구에서는 펄스레이져 박막 증착법(Pulsed Laser Deposition;PLD)을 이용하여 연자성의 CoNiFe (CNF) 물질과 강유전 특성의$BaTiO_3$ (BTO) 물질을 다층박막 구조로 제작하여 약자장(H=200 Oe)에 의해 에너지를 집적 시키거나 유전상수를 조절하여 박막의 구조 변화에 따른 커패시턴스 변화를 연구하였다. 다양한 구조의 다층 박막은 Si/$SiO_2$/Ti/Pt(111) 기판상에 PLD을 이용하여 증착하였으며, Phillp's X-선 회절기 (XRD)를 이용하여 결정구조와 격자 상수를 결정하였다. FE-SEM, TEM, AFM 및 EDS를 이용하여 박막 표면/단면의 미세구조 및 물질에 따른 조성비를 확인하였다. 자기적 특성을 위해Vibrating Sample Magnetometer (VSM)를 측정하였고, 전기적 특성은 LCR meter를 이용하여 측정하였다.

• Journal of Welding and Joining
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• v.15 no.5
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• pp.46-55
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• 1997

This study has evaluated the liquation cracking behavior in the heat affected zone of several Ni base superalloys (Incoloy 825, Inconel 718 and Inconel 600). 304 and 310S austenitic stainless steels were also included for comparison. In addition, the mechanism of liquation cracking in the HAZ was postulated based on the extensive microstructural examinations with SEM, EDAX and TEM. The liquation cracking resistance of Ni base alloys was found to be far inferior to that of austenitic stainless steels. The liquation cracking of Incoloy 825 and Inconel 718 was believed to be closely related with the Laves-austenite(Ti rich in 825 and Nb rich in 718) and MC-austenitic eutectic phases formed along the grain boundaries by constitutional liquation and incipient melting under rapid welding thermal contraction. Further, liquation cracking resistance of the HAZ was dependent not only upon the type and amount of low melting phases but also on the grain size.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1000-1001
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• 2006

Two atomized alloy powders were pre-compacted by cold and subsequently hot forged at temperatures ranging from 653K to 845K. The addition of Cu and Mg causes a decrease in the eutectic reaction temperature of Al-10Si-5Fe-1Zr alloy from 841K to 786K and results in a decrease of flow stress at the given forging temperature. TEM observation revealed that in addition to Al-Fe based intermetallics, $Al_2Cu$ and $Al_2CuMg$ intermetallics appeared. The volume fraction of intermetallic dispersoids increased by the addition of Cu and Mg. Compressive strength of the present alloys was closely related to the volume fraction of intermetallic dispersoids.

• Journal of Powder Materials
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• v.6 no.1
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• pp.111-118
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• 1999

Ni(Fe)Al powders containing a homogeneous distribution of the in-situ formed AIN and $Al_2O_3$ dispersoids have been produced by mechanical alloying process in a controlled atmosphere using high energy attrition mill. The powders have been successfully consolidated by hot extrusion process. The phase information investigated by TEM and XRD analysis reveals that Fe can be soluble up to 20% to the NiAl phase ($\beta$) at room temperature after MA process. Subsequent thermomechanical treatment under specific condition has been tried to induce secondary recrystallization (SRx) to improve high temperature properties, however, the clear evidence of SRx was not obtained in this material. Mechanical properties in term of strength at room temperature as well as at high temperatures have been improved by the addition pf AIN, and the room temperature ductility has been shown to be improved after heat treatment, presumably due to the precipitation of second phase of $\alpha$ in this material.

• Journal of Magnetics
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• v.22 no.1
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• pp.100-103
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• 2017

We studied the microstructure and magnetic properties of Fe nanosized powder synthesized by the pulsed wire evaporation method. The x-ray diffraction spectrum confirmed that this powder had a pure ${\alpha}$-Fe phase. Scanning electron microscope and transmission electron microscope measurements indicated that the prepared powder had uniform spherical shape with core-shell structure. The mean powder size was about 35 nm and the thickness of the surface passivation layer was about 5 nm. Energy dispersive X-ray spectroscopy measurement indicated that the surface passivation layer was iron oxide. Magnetic field dependent magnetization measurement at room temperature showed that the maximum magnetization of the prepared powder was 177.1 emu/g at 1 T.