• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.314-319
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• 2007

The destruction of synthetic acetic acid wastewater was carried out using UV, $O_3$, $H_2O_2$, $Fe^{2+}$ oxidants in various combinations by the advanced oxidation processes. $UV/H_2O_2$, $UV/H_2O_2/Fe^{2+}$, $O_3$, $O_3/H_2O_2$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes were tested. $UV/H_2O_2/Fe^{2+}$, $O_3/H_2O_2$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ processes shows the most effective destruction efficiency at low pH (3.5) condition of wastewater, but $UV/H_2O_2$ and $O_3$ processes were observed less than 20%. Destruction efficiency was gradually increased with the reaction time in the $O_3/H_2O_2$ and $UV/O_3/H_2O_2$ processes, in case of the $UV/H_2O_2/Fe^{2+}$ and $UV/O_3/H_2O_2/Fe^{2+}$ processes shows rapid increasing of destruction efficiency within 90 min, then slightly decreasing with time. The destruction efficiencies of $UV/H_2O_2/Fe^{2+}$, $O_3/H_2O_2$, $UV/O_3/H_2O_2$ and $UV/O_3/H_2O_2/Fe^{2+}$ processes were observed 55, 66, 66 and 64%, respectively.

• Korean Journal of Materials Research
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• v.11 no.1
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• pp.39-43
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• 2001

Nanocrystalline Fe-Sm-O thin films were prepared by RF magnetron reactive sputtering method in $Ar+O_2$mixed atmosphere with the $O_2$content of 5%. The compositions of the thin films were changed by changing the number of $Sm_2O_3$ chips. The best soft magnetic properties of the thin film with the composition of $Fe_{83.4}Sm_{3.4}O_{13.2}$ were saturation flux density of 18 kG, coercivity of 0.82 Oe and effective permeability about 2,600 at 0.5~100 MHz, respectively. The electrical resistivity of Fe-Sm-O thin films was increased with increasing the amount of Sm and O elements which combined each other, the electrical resistivity of$Fe_{83.4}Sm_{3.4}O_{13.2}$ thin film was $130{\mu}{\Omega}cm$. In case of the small amount of Sm and O elements, the microstructures of Fe-Sm-O thin films showed a precipitated phase of $Sm_2O_3$ on the ${\alpha}-Fe$ phase. With the increase of the amount of Sm and O elements, the microstructures of the Fe- Sm-O thin films were changed into a mixed structure of ${\alpha}-Fe$ crystal-phase and Sm-oxide amorphous phase. The Fe-Sm-O thin films with Fe content in the range of 72~94 at% exhibited the quality factor (Q = $\mu$′/$\mu$") of 7~75 up to 50 MHz.

• Journal of Magnetics
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• v.9 no.4
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• pp.101-104
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• 2004

The crystallization behaviours of nanocomposite made by a function of quenching rate (roller speed) were studied. The results showed that there was one step c$\mathbb{r}$ystallization process for the alloy quenched at roller speed of 32 m/s, which could be shown as, Am (amorphouse) + ${\alpha}-Fe/Nd_2Fe_{14}B$ ${\rightarrow}$ ${\alpha}-Fe/Nd_2Fe_{14}B$ . For the alloy quenched at roller speed of 40 m/s, there was steps crystallization process taking place at different temperatures, which could be shown as, Am ${\rightarrow}$ ${\alpha}-Fe/Nd_2Fe_{23}B_3+Nd_2Fe_{14}B+Am`$ ${\rightarrow}$ ${\alpha}-Fe/Nd_2Fe_{14}B$. The presence of transition phase ($Nd_2Fe_{23}B_3$) was harmful to get fine and uniform grain size during crystallization process. Uniform microstructures and high magnetic properties could be attained for the as-quenched alloy containing less amorphous phase and no presence of transition phase during annealing treatment. For the alloy prepared at roller speed of 32 m/s, the following properties were obtained, $B_r= 0.904 T,_iH_c = 801 kA/m, (BH)_{max} = 122 kJ/m^3 and M_r/M_s = 0.6$.

• Journal of the Korean institute of surface engineering
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• v.51 no.2
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• pp.104-109
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• 2018

Fe-2 wt.%Ni alloys were fabricated by metal powder injection molding, and their oxidation behavior at $600-700^{\circ}C$ for 30 h in air was studied in order to find the effect of the small addition of Ni in the iron matrix on the high-temperature oxidation. Oxide scales that formed after oxidation consisted primarily of $Fe_2O_3$, where microscopic voids were scattered. Nickel was segregated initially at the scale/matrix interface, and later at the lower part of the $Fe_2O_3$ scale. At $600^{\circ}C$, Fe-2wt.%Ni alloys oxidized parabolically initially, and linearly after 15 h. At $650-700^{\circ}C$, they oxidized linearly from the initial period. Although Fe-2wt.%Ni alloys oxidized slower than pure iron, their oxidation rates were relatively fast.

• Journal of Powder Materials
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• v.8 no.3
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• pp.157-162
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• 2001

An optimum route to fabricate the ferrous alloy dispersed $Al_2O_3$ nanocomposites such as $Al_2O_3$/Fe-Ni and $Al_2O_3$/Fe-Co with sound microstructure and desired properties was investigated. The composites were fabricated by the sintering of powder mixtures of $Al_2O_3$ and nano-sized ferrous alloy, in which the alloy was prepared by solution-chemistry routes using metal nitrates powders and a subsequent hydorgen reduction process. Microstructural observation of reduced powder mixture revealed that the Fe-Ni or Fe-Co alloy particles of about 20 nm in size homogeneously surrounded $Al_2O_3$, forming nanocomposite powder. The sintered $Al_2O_3$/Fe-Ni composite showed the formation of Fe$Al_2O_4$ phase, while the reaction phases were not observed in $Al_2O_3$/Fe-Co composite. Hot-pressed $Al_2O_3$/Fe-Ni composite showed improved mechanical properties and magnetic response. The properties are discussed in terms of microstructural characteristics such as the distribution and size of alloy particles.

• 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 Korea Institute of Military Science and Technology
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• v.15 no.2
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• pp.224-230
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• 2012

Thermal batteries have excellent mechanical robustness, reliability, and long shelf life. Due to these characteristics as well as their unique activation mechanism, thermal batteries are widely adopted as military power sources. Li(Si)/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as molten salt electrolyte. However, it is known that Li(Si)/$FeS_2$ thermal batteries have high internal resistance. Especially, $FeS_2$ cathode accounts for the greater part of internal resistance in unit cell. Many efforts have been put into to decrease the internal resistance of thermal batteries, which result in the development of new electrode material and new electrode manufacturing processes. But the applications of these new materials and processes are in some cases very expensive and need complicated additional processes. In this study, internal resistance study was conducted by adding carbon black and carbon nano-tube, which has high electron conductivity, into the $FeS_2$ cathode. As a results, it was found that the decrease of internal resistance of $FeS_2$ cathode by the addition of carbon black and carbon nano-tube.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.499-502
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• 2000

In this study, $\alpha$-Fe$_2$O$_3$thin films were deposited on $Al_2$O$_3$substrate by RF magnetron sputtering method from a $\alpha$-Fe$_2$O$_3$target(99.9%). The sputtering atmosphere was Ar and 80%Ar:20%O$_2$mixture in a total gas pressure of 1~3mTorr. As-deposited $\alpha$-Fe$_2$O$_3$thin films were heated to 300, 400, 500, $600^{\circ}C$ for 5hr in oxygen atmosphere. The structure and the morphology of $\alpha$-Fe$_2$O$_3$thin films were examined by scanning Electron microscopy(SEM) and the crystal structure was analyzed by X-Ray Diffractometer(XRD). The microstructure of the annealed $\alpha$-Fe$_2$O$_3$films exhibits rather gross particle and the grain size was less than 100nm. Since the grain size was very small, the gas sensitivity was expected to be improved.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.412-415
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• 1995

By adding 1wt.% $HfB_{2}$ into $Nd_{3-4}Fe_{77-78.5}B_{18.5}$ alloys, the grain growth of $Fe_{3}B/Nd_{2}Fe_{14}B$ composite phases during annealing was found to be hindered by 40~50%. It is proposed that the addition of $HfB_{2}$ leads to the formation of fine dispersoids of $HfB_{2}$ in the $Fe_{3}B/Nd_{2}Fe_{14}B$ composite magnet. The maximum energy product($(B.H)_{max}$) as well as intrinsic coercivity($_{i}H_{c}$) for the $Nd_{3}Fe_{78.5}B_{18.5}\;+\;1wt.%\;HfB_{2}$ alloy were enhanced by more than 25% $(B.H)_{max}=10\;MGOe,\;_{i}H_{c}=2.5\;kOe)$ due to the addition of $HfB_{2}$ while remanent magntization($B_{r}$) was reduced slightly. Itis deduced that the formation of fine dispersoids will also play a role of magnetic domain pinning.

• Journal of Powder Materials
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• v.28 no.1
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• pp.38-43
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• 2021

A high NIR-reflective black pigment is developed by Mn doping of Fe2O3. The pigment powders are prepared by spray pyrolysis, and the effect of the Mn concentration on the blackness and optical properties is investigated. Mn doping into the crystal lattice of α-Fe2O3 is found to effectively change the powder color from red to black, lowering the NIR reflectance compared to that of pure Fe2O3. The pigment doped with 10% Mn, i.e., Fe1.8Mn0.2O3, exhibits a black color with an optical bandgap of 1.3 eV and a Chroma value of 1.14. The NIR reflectance of the prepared Fe1.8Mn0.2O3 black pigment is 2.2 times higher than that of commercially available carbon black, and this material is proven to effectively work as a cool pigment in a temperature rise experiment under near-infrared illumination.