• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.963-968
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• 2000

Magnetic properties and microstructures of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were investigated as a function of addition of element Ag, (X$\_$Ag/=0 to 6 at.%) and annealing temperature, T$\_$a/=300$\^{C}$ to 600$\^{C}$. In the case of adding Ag, magnetic properties of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were improved than those of Ag-free Fe$\_$93/Zr$_3$B$_4$thin films. The prominent soft magnetic properties with coercivity of 1.1 Oe, saturation magnetization of 2.2 T and permeability of 5400 at 50㎒ were obtained from Fe$\_$88/Zr$_3$B$_4$Ag$\_$5/ thin film annealed was lower than that of Fe-base or Co-base thin films reported previously. Such enhanced magnetic properties are presumably attributed to the format in ultra fine grains. Also, the reduced eddy current loss in the annealed sample is due to refined micro magnetic domains with increasing the amount of Ag in Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films.

• Journal of Applied Biological Chemistry
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• 제61권4호
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• pp.383-389
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• 2018

Degradation of the insecticide O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate (chlorpyrifos) in aqueous solution was investigated using iron salts and potassium persulfate during ZVI treatment through a series of batch experiments. The degradation rate of chlorpyrifos increased with increases in the concentrations of iron salts and potassium persulfate in the aqueous system. Ferric chloride was found to be the most effective iron salt for the ZVI-mediated degradation of chlorpyrifos in aqueous solution. Further, the iron salts tested could be arranged in the following order in terms of their effectiveness: $FeCl_3$> $Fe_2(SO_4)_3$> $Fe(NO_3)_3$. The persulfate-ZVI system could significantly degrade chlorpyrifos present in the aqueous medium. This revealed that chlorpyrifos degradation by treatment with $Fe^0$ was promoted on adding ferric chloride and potassium persulfate. The kinetics of the degradation of chlorpyrifos by persulfate-amended $Fe^0$ was higher than that for iron-salt-amended $Fe^0$. This suggests that using a sequential $Fe^0$ reduction-ferric chloride or $Fe^0$ reduction-persulfate process may be an effective strategy to enhance the removal of chlorpyrifos in contaminated water.

• 한국분말재료학회지
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• 제30권2호
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• pp.116-122
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• 2023

Because magnets fabricated using Nd-Fe-B exhibit excellent magnetic properties, this novel material is used in various high-tech industries. However, because of the brittleness and low formability of Nd-Fe-B magnets, the design freedom of shapes for improving the performance is limited based on conventional tooling and postprocessing. Laser-powder bed fusion (L-PBF), the most famous additive manufacturing (AM) technique, has recently emerged as a novel process for producing geometrically complex shapes of Nd-Fe-B parts owing to its high precision and good spatial resolution. However, because of the repeated thermal shock applied to the materials during L-PBF, it is difficult to fabricate a dense Nd-Fe-B magnet. In this study, a high-density (>96%) Nd-Fe-B magnet is successfully fabricated by minimizing the thermal residual stress caused by substrate heating during L-PBF.

• 한국재료학회지
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• 제33권9호
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• pp.353-359
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• 2023

This study investigated the growth behavior and characteristics of compounds formed at the interface between a liquid Al-Si-Cu alloy and solid cast iron. Through microstructural analyses, it was observed that various AlFe and AlFeSi phases are formed at the interface, and the relative proportion of each phase changes when small amounts of strontium are added to the Al alloy. The results of the microstructural analysis indicate that the primary phases of the interfacial compounds in the Al-Si-Cu base alloy are Al₈Fe₂Si and Al_4.5FeSi. However, in the Sr-added alloys, significant amounts of binary AlFe intermetallic compounds such as Al₅Fe₂ and Al₁₃Fe₄ formed, in addition to the AlFeSi phases. The inclusion of Sr has a slight diminishing effect on the rate at which the interfacial compounds layer thickens during the time the liquid Al alloy is in contact with the cast iron. The study also discusses the nano-indentation hardness and micro-hardness of the interfacial phases.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.185-194
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• 2024

Fe-Ni nanocatalysts loaded on carbon black were prepared via spontaneous reduction reaction of iron (II) acetylacetonate and nickel (II) acetylacetonate in dry process. Their morphology and elemental analysis were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analyzer. The loading weight of the nanocatalysts was measured by thermogravimetric analyze and the surface area was measured by BET analysis. TEM observation showed that Fe and Ni nanoparticles was well dispersed on the carbon black and their average particle size was 4.82 nm. The loading weight of Fe-Ni nanocatalysts on the carbon black was 6.83-7.32 wt%, and the value increased with increasing iron (II) acetylacetonate content. As the Fe-Ni loading weight increased, the specific surface area decreased significantly by more than 50%, because Fe-Ni nanoparticles block the micropores of carbon black. I-V characteristics showed that water electrolysis performance increased with increasing Ni nanocatalyst content.

• 한국재료학회지
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• 제7권2호
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• pp.136-139
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• 1997

증착법을 이용하여 $Sm(Co_{1-x}Fe_{x})$ 및 $Sm_{2}(Co_{1-x}Fe_{x})_{17}$(X=0, 0.3,0.5,0.7)박막을 제작하여 조성변화 및 열처리 온도 변화에 따른 자기적 성질의 변화에 대해 검토 하였다. Fe의 양이 증가 할 수록 포화자화 값은 증가 하지만 각형비는 감소하였고 보자력도 약간 감소하는 경향을 보였다. $Sm(Co_{0.5}Fe_{0.5})_{5}$ 조성박막의 경우, $800^{\circ}C$, 20분 열처리에 의해 약 6.1MGOe의 $(BH)_{max}$을 보였다. 본 박막자석의 자기적 성질의 증대를 위해서는 시료제작 방법의 개선이 필요하다고 사료 된다.

• Journal of Advanced Marine Engineering and Technology
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• 제10권4호
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• pp.57-66
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• 1986

The microstructure and mechanical properties of unidirectionally solidified Al-Fe-Ni and Al-Fe-B alloys have been studied in varying the some conditions. To investigate the change of microstructure and mechanical properties was carried out by the varying the composition and solidification rate from 1.2 to 80 mm/min at temperature gradient 60 .deg. C/cm. The results obtained are as follow; 1. In proportion to the increase of the solidification rate, the type of crystallized phase of these composite alloys was changed by added element. a) The crystallized phase of composite alloy in added nikel was changed from the rod-type fiber to platetype fiber. b) The crystallized phase of composite alloy in added boron was changed from the plate-type fiber to rod-type fiber. 2. The strength was rapidly increased with the changing process of crystallized fiber from the plate-type fiber to the rod-type.

• Journal of Microbiology
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• 제38권3호
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• pp.180-182
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• 2000

The inhibitory effects of nitrate on Fe(III) and humic acid reduction were examined in Shewanella putrefaciens DK-1. Therer is no difference in Fe(III) reduction until 25 hours between cultures using Fe(III) production was decreased drastically when Fe(III) and nitrate were used as electron acceptors. The production of AHQDS(2,6-anthrahydroquinon disulfonate) showed similar patterns when AQDS alone and both AQDS and Fe(III) were used as electron acceptors. When AQDS(2,6-anthraquinon disulfonate) and nitrate were used as electron acceptors, the production of AHQDS was completely inhibited.

• 소성∙가공
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• 제15권4호
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• pp.319-325
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• 2006

The laser forming process is a new flexible forming process without forming tools and external force, which is applied to various fields of industry. Especially, applications of the laser forming process focused on cutting, welding and marking process. In this paper, the laser bending process of sheet metal which is heated by laser beam and formed by internal stress is simulated by using thermo elastic-plastic analysis model. Based on the result of FE-analysis, the laser bending machine is made to obtain reliable data for sheet bending. Under the same condition as FE-analysis, the laser bending experiment has been performed to ver 펴 the result of FE-analysis and good agreement has been obtained between FE-analysis and experiments. Additional laser bending experiments have been performed to evaluate the laser bending machine.

• Journal of Magnetics
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• 제13권2호
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• pp.76-80
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• 2008

This study examined the magnetic properties of ultrathin Fe/Ni films on a Cu(001) surface using the full potential linearized augmented plane wave (FLAPW) method. The magnetic moment of Fe/Ni films was found to be insensitive to strain. Nevertheless, strain had a significant influence on the magnetization direction. For example, Fe/Ni films showed a thickness-dependent spin reorientation transition in the presence of strain, while the Fe/Ni films grown pseudomorphically on Cu(001) always showed perpendicular magnetization. In addition, the theoretically calculated X-ray magnetic circular dichroism (XMCD) was examined.