• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.3
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• pp.193-200
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• 2004

This pot experiment was conducted to investigate the effects of systematic variation application of Fe, Mn, Cu, and Zn on forage performance of orchardgrass and white clover. The treatments of systematic variation were 0/100, 25/75, 50/50, 75/25, and $100/0\%$ in the Fe/Cu(trial-1), Mn/Zn(trial-2), and Fe+Cu/Mn+Zn(trial-3), respectively. The treatments of Fe/Mn/Cu/Zn(trial-4) were composed of $70\%$ in main element and $10\%$ in other 3 elements, respectively. 1. By the systematic variations of Fe, Mn, Cu, and Zn, the yields were more significantly influenced in white clover than in orchardgrass. In addition, the yields of white clover were closely correlated to the trends of root/nodule growth and flowering. In the Fe/Cu trial, the relatively high yields were obtained at the $100/0\%$ in orchardgrass and at the $75/25\%$ in white clover. The yields of white clover were more negatively influenced by the 100/0(Cu control) than by the 0/100(Fe control). The yields of orchardgrass, however, tended to be opposite to the above trends. 2. In the Mn/Zn trial, both forages showed generally high yields at the high ratios of Mn/Zn. Compared with orchardgrass, the yields of white clover were greatly decreased by the Mn-deficiency(low ratio of Mn/Zn). The effects of Zn on forage yields, however, were not recognized. 3. In the Fe+Cu/Mn+Zn trial, the yields of orchardgrass tended to be slightly different among the treatments. The yields of white clover, however, were relatively' high at the 75/25, and showed a severe decrease at the 100/0 in the 2nd half cuts. In the Fe/Mn/Cu/Zn trial, the yields of white clover tended to be relatively high at the Cu and Zn treatments. It was likely to be caused by the balanced Fe/Mn ratio.

• Journal of the Korean Magnetics Society
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• v.13 no.3
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• pp.97-102
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• 2003

Synthetic ferrimagnetic layer (SyFL) with structure NiFe/Ru/NiFe which can be applied high density TMR device in free layer were prepared by an inductively coupled plasma (ICP) helicon-sputter. We proposed a model of predicting coercivity (H$\_$c/), spin-flopping field (H$\_$sf/), and saturation field (H$\_$s/) as a function of Ru thicknesses, from the equilibrium state of energies of Zeeman, exchange, and uniaxial anisotropy. We fabricated the samples of Ta(50 ${\AA}$)/NiFe(50${\AA}$)nu(4∼20${\AA}$)NiFe(30 ${\AA}$)/Ta(50${\AA}$), and measured the M-H loops with a superconduction quantum interference device (SQUID) applying the external field up to ${\pm}$ 15 kOe. The result was well agreed with the proposed model, and reveal K$\_$u = 1000 erg/㎤, J$\_$ex/ =0.7 erg/$\textrm{cm}^2$. We report that H$\_$c/ below 10 Oe is available, and R$\_$u/ thickness range should be in 4-10 ${\AA}$ for MRAM application. Our result implies that permalloy layers may lead to considerable magnetostriction effect in SyFL and intermixing in NiFe/Ru interfaces.

• Journal of the Korean Magnetics Society
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• v.10 no.2
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• pp.67-73
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• 2000

Top spin valve samples with a structure Ta/NiFe/CoFe/Cu/CoFe/FeMn/Ta were deposited on a Si(100) substrate by changing d.c. magnetron sputtering conditions and the exchange-bias and magnetic properties of samples were investigated. The Exchange field, H$\_$ex/ increased with increase of sputtering power of FeMn from 30 to 150 W and CoFe from 30 to 100 W deposited on the Cu, the increase of H$\_$ex/ was found due to the improvement of preferred orientation of (111) FeMn phase from XRD results. In the case of Cu, H$\_$ex/ decreased with the increase of sputtering pressure ranging from 1 to 5 mTorr. The relationship between exchange field and resistance was investigated, spin valve samples with a large exchange field showed the lower resistance, which was strongly dependent on the good crystallinity and grain size increase as well as lower scattering effects. The Cu thickness was changed from 22 to 38 $\AA$ for Si/Ta/NiFe/CoFe/Cu(t), 30 W/CoFe, 100 W/FeMn, 100 W/Ta spin valve structures, MR ratio of 6.5 % and exchange field of about 190 Oe were obtained for the sample with Cu of 22 $\AA$ thickness. The increase of exchange field with decrease of Cu thickness was explained by FM/AFM spin-spin interaction.

• Corrosion Science and Technology
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• v.13 no.2
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• pp.41-47
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• 2014

The isothermal corrosion tests of several types of stainless steels, Ni-based alloys, and ferritic-martensitic steels (FMS) were carried out at the temperature of 550 and $650^{\circ}C$ in SFR S-$CO_2$ environment (200 bar) for 1000 h. The weight gain was greater in the order of FMSs, stainless steels, and Ni-based alloys. For the FMSs (Fe-based with low Cr content), a thick outer Fe oxide, a middle (Fe,Cr)-rich oxide, and an inner (Cr,Fe)-rich oxide were formed. They showed significant weight gains at both 550 and $650^{\circ}C$. In the case of austenitic stainless steels (Fe-based) such as SS 316H and 316LN (18 wt.% Cr), the corrosion resistance was dependent on test temperatures except SS 310S (25 wt.% Cr). After corrosion test at $650^{\circ}C$, a large increase in weight gain was observed with the formation of outer thick Fe oxide and inner (Cr,Fe)-rich oxide. However, at $550^{\circ}C$, a thin Cr-rich oxide was mainly developed along with partially distributed small and nodular shaped Fe oxides. Meanwhile, for the Ni-based alloys (16-28 wt.% Cr), a very thin Cr-rich oxide was developed at both test temperatures. The superior corrosion resistance of high Cr or Ni-based alloys in the high temperature S-$CO_2$ environment was attributed to the formation of thin Cr-rich oxide on the surface of the materials.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.713-717
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• 2001

The magnetic and magnetostrictive properties of amorphous Tb/sub 45.7/Fe/sub 54.3-x/Co/sub x/ and Tb/sub 50.2/Fe/sub 49.8-x/Co/sub x/ (0≤x≤9.6) thin films have systematically been investigated. The films were fabricated by rf magnetron sputtering using a composite target which consists of a Fe plate and Tb, Co chips. The microstructure mainly consists of an amorphous phase. Excellent intrinsic and low magnetic-field-magnetostrictive properties were achieved in Tb/sub 45.7/Fe/sub 54.3-x/Co/sub x/ and Tb/sub 50.2/Fe/sub 49.8-x/Co/sub x/ (0≤x≤9.6). The magnetostriction of 130 ppm was obtained with low field of 100 Oe. The intrinsic magnetostriction(applied field, 5 kOe) were increased from 330ppm to 400ppm.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1159-1164
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• 1997

Magnetite(Fe3O4) powders were synthesized through glycothermal reaction by using crystalline $\alpha$-FeOOH as precursor and ethyleanne glycol as solvent. The phase, morphology and particle size of synthesized powders were characterized by XRD and an SEM. When only ethylene glycol was used as solvent, the phase was transformed from $\alpha$-FeOOH to $\alpha$-Fe2O3 and finally Fe3O4 at 27$0^{\circ}C$ for 6hr without morphological change. But by addition of water, Fe3O4 powders were synthesized at 23$0^{\circ}C$ for 3hr through solution-recrystalization process. As the content of water addition increased, the particle shape changed from sphere to octahedron and the partcle size increased. When the excess amount of water added, residual $\alpha$-FeOOH or $\alpha$-Fe2O3 was recrystalized.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.52-58
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• 2004

The surface property and formation behavior of a boride layer formed on Ni-Cr-Mo steel in a plasma paste boronizing treatment were investigated. The plasma paste boronizing treatment was carried out at 973～1273 K for 1-7 hrs under the gas ratio of Ar:H$_2$ (2:1). The thickness of the boride layer increased with increasing temperature and time in the boronizing treatment. The cross-section of the boride layer was a tooth structure and the hardness was Hv 2000～2500. XRD analysis revealed that the compound was identified as FeB, $Fe_2$B, and mixed phase of FeB/$Fe_2$B in the boride layer formed at 973～1073 K, 1173K, and 1273K, respectively. The Ni-Cr-Mo alloy boronized at 1173-1273 K showed the best excellent wear resistance against the sand. As a results of corrosion test in 1 M $H_2$$SO_4$ solution, $Fe_2$B formed on the matrix alloy exhibited higher corrosion resistance than FeB.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.70-75
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• 2005

The damping property of Fe-12Cr-22Mn-X alloys has been investigated to develop high damping and high strength alloy. Particularly, the effect of the phase of austenite, alpha and epsilon martensite, which constitute the structure of the alloys Fe-12Cr-22Mn-X alloys, on the damping capacity at room temperature has been investigated. Various fraction of these phases were formed depending on the alloy element and cold work degree. The damping capacity is strongly affected by ${\varepsilon}$ martensite while the other phase, such as ${\alpha}'$ martensite, actually exhibit little effect on damping capacity. In case of Fe-12Cr-22Mn-3Co alloy, the large volume fraction of ${\varepsilon}$ martensite formed at about 30% cold rolling, and in case of Fe-12Cr-22Mn-1Ti alloy, formed at about 20% cold rolling and showed the highest damping capacity. Damping capacity showed higher value in Fe-12Cr-22Mn-1Ti alloy than one in Fe-12Cr-22Mn-3Co alloy.

• Journal of Powder Materials
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• v.11 no.2
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• pp.105-110
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• 2004

In this study the possibility to obtain a homogeneous mixture and to produce solid solutions and intermetallic compounds of Fe and Al nano particles by simultaneous pulsed wire evaporation (S-PWE) have been investigated. The Fe and Al wires with 0.45 mm in diameter and 35 mm in length were continuously co-fed by a special mechanism to the explosion chamber and simultaneously exploded. The characteristics, e.g., phase composition, particle shape, and specific surface area of Fe-Al nano powders have been analyzed. The synthesized powders, beside for Al and $\alpha$-Fe, contain significant amount of a high-temperature phase of $\gamma$-Fe, Fe Al and traces of other intermetallics. The phase composition of powders could be changed over broad limits by varying initial explosion conditions, e.g. wire distance, input energy, for parallel wires of different metals. The yield of the nano powder is as large as 40 wt ％ and the powder may include up to 46 wt % FeAl as an intermetallic compound.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.511-515
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• 1995

Since much studies have been performed concerning the electrochemical behaviors and the practical applications of PB based devices, little has yet reported to investigate the best condition for the preparation for PB thin films. As considered some factors(peak shape, peak current, and peak separation) from the i-V curves, the optimal condition in the film growth were investigated under various immersion solutions. An electron-transfer processes of Fe2+/Fe3+ and Fe(CN)63-/4- redox couples were considered by measuring the observed currents as a function of the rotation velocity. The standard heterogeneous electron-transfer rates for these films and bare Au disc electrode in 10-3 M Fe2+/Fe3+ solution, applied at +0.65 V vs. SCE, were 6.14 × 10-3 and 7.78 × 10-3 cm/s, respectively, obtained using a rotating disc electrode. In case of the addition of potassium ion, the rate constants for these Fe2+/Fe3+ system on thin films of PB and bare electrode were given a little high values. The electron transfer rate for 10-3 M Fe(CN)63-/4- were 4.55 × 10-3 and 6.84 × 10-3 cm/s, respectively. The conductivity as directly determined during obtained the voltammogram, was 2.2 × 10-7 (Ω·cm)-1. This value is similar magnitude to that calculated from bulk sample.