• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.17-22
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• 1999

Hexagonal M-type barium ferrite $BaFe_{12}O_{19}$ was prepared by a direct solid state reaction between $BaCO_3$ and ${\Alpha}-Fe_2O_3$ powders at temperatures ranging from 800 to 1000 $^{\circ}C$ in a nitrogen or air environment. The effects of NaCl on phase transformation of mixture of $BaCO_3$ and ${\Alpha}-Fe_2O_3$ to $BaFe_{12}O_{19}$ were studied using X-ray diffraction and M$\"{o}$ssbauer spectroscopy. Regardless of the environment for heat treatment or the added NaCl, two phases, BaFe and ${\Alpha}-Fe_2O_3$, coexist for samples heat treated at 800 $^{\circ}C$, but a single phase was observed from samples heat treated at 100$0^{\circ}C$ in both air and nitrogen environments. It was found that the addition of NaCl reduced the amount of $a-Fe_2O_3$ phase.hase.

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1308-1311
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• 1997

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.123.2-123.2
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• 2017

Fe-Ni-Cu 합금 전주를 위하여 황화물 용액에의 상의 열역학적 안정도를 작성하고 전주 조건을 선정하였다. $Fe-Ni-Cu-S-H_2O$ 용액의 열역학적 상의 안정도를 전산모사하기 위한 프로그램은 C#으로 작성하였다. JANAF 자료를 근거한 적정 전주 조건은 $130mA/cm^2$, $50{\sim}55^{\circ}C$, pH 2.4 이었다. XRF을 이용한 Fe-Ni-Cu의 합금 도막의 평균 조성은 Fe-42Ni-1Cu [wt.%] 이었다, 전류밀도가 낮아질수록 Ni과 Cu량은 증가하였다. 구리 농도가 증가하면 표면조도는 60 nm로 변화하였다.

• Journal of the Korean institute of surface engineering
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• v.40 no.5
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• pp.219-224
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• 2007

The corrosion characteristics of Fe-18Cr-10Ni steels were studied between $600^{\circ}C$ and $1000^{\circ}C$ in Ar+(0.2, 1)%$SG_2$ gas for up to 300 hr in order to employ Fe-18Cr-10Ni steels in the coal-fired power plants. The corrosion resistance of Fe-18Cr-10Ni steels was good due mainly to the high amount of Cr, which formed $Cr_2O_3$ from the initial corrosion stage. Fe in the steels corroded to mainly $Fe_2O_3$ and $Fe_3O_4$. Ni was not susceptible to corrosion under the current corrosion condition. Relatively thin, single-layered scales formed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1760-1767
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• 2010

FAT compounds photocatalysts were prepared with $TiOSO_4{\cdot}xH_2O$ (TOS) by a sol-gel method. The samples were characterized by scanning electron microscopy (SEM), BET specific surface area, X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDX). The SEM results showed that ferric compounds and titanium dioxide were fixed onto the AC surfaces. The XRD results showed that Fe-AC/$TiO_2$ composites mostly contained anatase phase. EDX showed the presence of C, O, and Ti with Fe peaks in all samples. The photocatalytic activities were evaluated by the photocatalytic oxidation of methylene blue (MB) solution, via compare photodegradation of MB solution under visible light and UV light separately. Fe-AC/$TiO_2$ composites had an excellent photocatalytic under strong visible light irradiation. A small amount of Fe ions in AC/$TiO_2$ particles could obviously enhance their photocatalytic activity.

• Corrosion Science and Technology
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• v.3 no.3
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• pp.98-101
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• 2004

The corrosion behavior of Al-Fe coatings was studied in the wet-seal atmosphere of molten carbonate fuel cells (MCFC). Fe-8Al, Fe-16Al, Fe-25Al, Fe-36Al, and Fe-70Al (in at.%) specimens were tested in Li/K carbonate at $650^{\circ}C$ by a single cell test and an immersion test. In general, the corrosion resistance of the Al-Fe coatings was enhanced due to the formation of a protective $LiAlO_2$ layer. However, when the Al-Fe coatings didn't have sufficient content of aluminum enough for maintaining the protective layer, the corrosion resistance of the Al-Fe coatings was severely degraded by the growth of non-protective scales like $LiAlO_2$. The test results revealed that the aluminum contents in the coatings should be higher than 25 at.% in order to form and maintain the protective $LiAlO_2$ layers.

• Journal of the Korean Magnetics Society
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• v.11 no.5
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• pp.211-216
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• 2001

Top synthetic spin valves wi th structure Ta/NiFe/CoFe/Cu/CoFe(Pl)/Ru/CoFe(P2)/FeMn/Ta on Si (100) substrate with SiO$_2$ of 1500 were prepared by dc magnetron sputtering system. We have changed only the thickness of the free layer and the thickness difference (Pl-P2) in the two ferromagnetic layers separated by Ru, and investigated the effect of magnetic film thickness on the GMR properties and the interlayer coupling field in a spin valve with a synthetic antiferromagnet. As thickness difference of pinned layer was decreased from +25 to -25 , MR ratio was decreased gradually. However, there was a dip zone indicating a big change of MR ratio around Pl = P2, which can be due to the large canting of pinned layers. The modified Neel model was suggested for the top synthetic spin valve to explain the interlayer coupling field according to the thickness change of ferromagnetic layers. The interlayer coupling field was decreased due to the magnetostatic coupling (orange peel coupling) as suggested by model. However, the interlayer coupling field was not explained at the dip zone by the modified Neel model. The deviation of modified Neel model at the dip zone could be due to the largely canting of the pinned layers as well, which depends on different thickness in synthetic antiferromagnetic structure.

• Journal of the Korean Ceramic Society
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• v.18 no.3
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• pp.152-156
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• 1981

$Fe_2O_3$ was reduced over the temperature range of 600-100$0^{\circ}C$ in both the atmospheres for the Fe-stable and FeO-stable states. It was found that the reduction follows first order kinetics and the reduction of $Fe_3O_3$ to $Fe_3O_4$ is the rate-controlling step.

• Journal of the Korean Magnetics Society
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• v.18 no.6
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• pp.217-220
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• 2008

We have investigated the magnetic properties of $ErFe_2O_4$. Stoichiometric polycrystalline sample of $ErFe_2O_4$ was prepared by solid-state reaction method in a stream of CO/$CO_2$ gas. The X-ray power diffraction pattern shows that the diffraction peaks are indexed with respect to the rhombohedral structure with a space group of R3m. The temperature dependent magnetization for $ErFe_2O_4$ shows two-step phase transitions at about 220 and 250 K. The transition at 250 K is an antiferromagnetic transition and that at 220 K is a structural transition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1883-1889
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• 2013

Although Fe-Si based alloy has lower figure of merit than Si-Ge alloy applied for space probe, its low cost related to abundant raw material, rather simple processing, high temperature resistance and reliability up to $800^{\circ}C$ made it one of the most promising middle temperature thermoelectric generation materials. The effect of particle size and additive on the thermoelectric properties of p-$FeSi_2$ prepared by a RF inductive furnace was investigated. The electrical conductivity increased slightly with decreasing particle size and hence better grain-to-grain connectivity due to the increase of density. The Seebeck coefficient exhibited the maximum value at about 600~800K and decreased slightly with increasing particle size. This must be due to the amount of residual metallic phase ${\varepsilon}$-FeSi. $Fe_2O_3$ and/or $Fe_3O_4$-doped specimens showed the higher electrical conductivity and the lower Seebeck coefficient due to increase of the metallic phase and Si-vacancy. On the other hand, $SiO_2$-doped specimen showed the higher electrical conductivity and the higher Seebeck coefficients.