• Journal of the korean Society of Automotive Engineers
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• v.11 no.6
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• pp.38-47
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• 1989

The Finite Element Method has been employed to calculate the effect of particle size, matrix, and volume fractions on the stress-strain relations of .alpha.-.betha. titanium alloys. It was found that for a given volume fraction, the calculated stress-strain curve was higher for a finer particle size than for a coarse particle size within the range of the strains considered, and this behavior was seen for all the different volume fraction alloys considered. The calculated stress-strain curves for three vol. pct .alpha. alloys were compared with their corresponding experimental curve, and in general, good agreement was found.

• Resources Recycling
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• v.13 no.6
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• pp.9-15
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• 2004

The optimum conditions were studied for the preparation of transparent iron oxide with the air oxidation of FeOOH. The FeOOH obtained by mixing NaOH and FeSO$_4$ solution in various conditions such as R(=2NaOH/FeSO$_4$), FeSO$_4$ concentration. reaction temperature and air flow rate. When the FeSO$_4$ increased gradually, the concentration of iron ion in the solution became high. So, particle size increased precipitating Fe$_3O_4$. Goethite dehydrate at about 200$^{\circ}C$ and ended the reaction at about 320$^{\circ}C$ forming hematite. The lower the reaction temperature was, the shorter the particle length of goethite and particle size decreased. When the flow rate of air as an oxidant increased, the amount of dissolved oxygen in the solution increased, which made oxidation rate increased. And then particle size of goethite decreased.

• Journal of Magnetics
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• v.4 no.4
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• pp.123-127
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• 1999

The Ga-stabilised $Sm_2Fe_{17-}$type alloy can hardly be disproportionated under ordinary HDDR condition. The HDDR characteristics of Ga-substituted $Sm_2Fe_{17-}$type alloy were examined, and, in particular, the effect of particle size on the disproportionation of the Ga-substituted alloy was investigated in detail. The reaction characteristics of the $Sm_2Fe_{17-}$type alloys with or without Ga-substitution with methane (CH4) gas are also examined. The Ga-stabilised $Sm_2Fe_{17-}$type alloy was able to be disproportionated significantly on heating up to 80$0^{\circ}C$ under hydrogen with normal pressure. The particle size influenced significantly on the disproportion-ation of the Ga-substitute alloy, and the materials with finer particle size (<40 ${\mu}{\textrm}{m}$) was fully disproportionated on heating up to around 80$0^{\circ}C$ under hydrogen gas with normal pressure. The Ga-substituted alloy has a very sluggish recombination kinetics with respect to the alloy without Ga-substitution. The $Sm_2Fe_{17}C_{x-}$type carbide was stabilised significantly by the Ga-substitution for Fe in the parent alloy. While the $Sm_2Fe_{17}C_x$ was disproportionated below 80$0^{\circ}C$ the Ga-stabilised $Sm_2Fe_{14}Ga_2C_x$ carbide remained intact even on heating up to 80$0^{\circ}C$.

• Journal of Korea Foundry Society
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• v.10 no.2
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• pp.154-161
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• 1990

The microstructures of sintered products of $Fe_2O_3$or $Fe_3O_4$-Oxide added cast iron powder was investigated. And the effects of particle size distribution was investigated too. As the result, the structures of sintered products did not related to the species of Fe-Oxide. Th porosity of sintered products was decreased in size and spherodized with increasing sintering temperature, decreasing Fe-Oxide quantity. Fe-Oxide itself did not hinder sintering of cast iron powder particularly, therefore sintering could be occurred without termination of reduction of it. And the sintered products of finer particle size distribution had finer and more spherodized porosity, and had minimized the deviation of size and shape of porosity.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.98-104
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• 2008

This research was performed to evaluate the extraction characteristics of heavy metals for soil washing of mine tailings-contaminated soil according to particle size distribution and the chemical distributional existence of the metals. As the soil particle size was decreased, the extracted concentrations of heavy metals was increased except Fe and Mn. Most of all heavy metals were extracted within 6 h by soil washing with 0.05 M EDTA. Extraction efficiency of metals was decreased for Pb, Cu, and Zn with decreasing of particle size. Significant difference was not observed in extraction efficiency for Cd according to particle size distribution. Extraction efficiency for Cd was the highest as 86~91%, while the lowest as 5~14% for Fe. Most metals of the soil without soil washing was distributed as reducible, oxidizable, and residual fractions. Pb, Zn, and Cd existed as reducible (Fe/Mn oxide) and residual fractions and Cu existed as oxidizable and residual fractions after soil washing treatment with 0.05 M EDTA. As the soil particle size was decreased, residual fraction was increased for Pb and Cu. About 90% of reducible fraction in Pb, Zn, and Cd was removed by soil washing with 0.05 M EDTA. As the results, it was founded that soil particle size was the important parameter to effect on distributional fraction and extraction efficiency of metals in mine tailings-contaminated soil.

• Journal of the Korean Ceramic Society
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• v.34 no.5
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• pp.453-460
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• 1997

Sr-ferrite having magnetoplumbite structure is similar to Ba-ferrite in magnetic characteristics, but better magnetic characteristics for using motor application. To improve remanence magnetic flux density(Br) and coercive force(iHc), it is necessary that sintered ferrites must have high density and grain size less than 1 $\mu$m. By varying n values in SrO.nFe2O3 basic composition, calcination temperature, and BaO addition, Sr-ferrite powder and sintered specimen was prepared. The n values, calcination temperature, and BaO addition affected secondary phase formation, particle size, and particle shape. BaO addition enhanced Fe2O3 secondary phase and hexagonal shape particle. Fe2O3 phase reduced sintered density which greatly decreased Br.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.63-69
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• 2007

The present study was focused on the synthesis of a zirconium-based alloyed nanopowder by the plasma arc discharge process. The chemical composition, phase structure, particle size and hydrogen sorption property of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD, SEM, XPS and the ASTM-F798 method. The chemical composition of the synthesized Zr-V-Fe-based powders approached that of the raw material with an increasing hydrogen fraction in the powder synthesis atmosphere. The synthesized $Zr_{55}V_{29}Fe_{16}$ powder consist of a mixed phase structure of the $Zr,\;ZrH_2,\;FeV\;and\;Zr(V_{1-x}Fe_{x})_2$ phases. This powder has an average particle size of about 20 nm. The synthesized $Zr_{55}V_{29}Fe_{16}$ nanopowder showed getter characteristics, even though it had a lower hydrogen sorption speed than the $Zr_{57}\;V{36}\;Fe_7$ getter powder. However, the synthesized Zr nanopowder with an average particle size of 20 nm showed higher hydrogen sorption speed than the $Zr_{57}\;V{36}\;Fe_7$ getter powder.

• Journal of Magnetics
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• v.6 no.3
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• pp.94-100
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• 2001

Fe-Co-Ni particles with an average size of 45 and 135 nm are characterized in terms of magnetic phase transformation and magnetic properties at room temperature. BCC structure of Fe-Co-Ni spherical particles can be synthesized from Fe-Co-Ni-Al-Cu precursor films by heating at 600-80$0^{\circ}C$ for the phase separation of Fe-Co rich Fe-Co-Ni particles, followed by a post heating at $600^{\circ}C$ for 5 hours. The average size of nanoparticles was directly determined by the thickness of precursor films. Exchange interactive hysteresis was observed for the nano-composite (Fe-Co-Ni)+(Fe-Ni-Al) films resulting from the short exchange interface between ferromagnetic Fe-Co-Ni particles surrounded by almost papramagnetic Ni-Al-Fe matrix. Arraying the isolated Fe-Co-Ni nano-particles in a random arrangement on $Al_2O_3$substrate the particle assembly showed a behavior of dipole interactive ferromagnetic clusters depending on their volume and inter-particle distance.

• Journal of Magnetics
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• v.22 no.2
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• pp.188-195
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• 2017

The ferromagnetic resonance and other magnetic properties dependence on $Ni^{2+}/Fe^{3+}$ ratio and crystallite size were investigated for nano nickel ferrite ($NiFe_2O_4$). The crystallite size was controlled by controlling the nickel content in the starting material solution. The XRD and TEM were utilized to measure the crystallite size through Scherrer formula and particle size respectively. The most frequent particle sizes were lower than crystallite size, which ranged from 16.5 to 44.65 nm. The general behavior of M-H loop shapes and parameters showed superparamagnetic one. The saturation magnetization had a maximum value at $Ni^{2+}/Fe^{3+}$ molar ratio equal to 0.186. The FMR signals showed, generally, broad linewidths, where the maximum width and minimum resonance field were for the sample of the lowest crystalline size. Furthermore, FMR resonance field shows linear dependence on crystalline size. The fitting relation was estimated to express this linear dependency on the base of behavior coincidence between particle size and the inverse of saturation magnetization. The given interpretations to understand the intercept and the slope meanings of the fitted relation were based on Larmor equation, and inhomogeneous in the anisotropy constant.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.149-153
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• 2001

This paper describes on the fabrication of Fe-Co hydrophilic magnetic fluids from the waste pickling liquor of steel. By adding with HNO$_3$in the waste liquor oxidation is proceeded from Fe$^{3+}$ion at 6$0^{\circ}C$ with air blowing. Ultra-fine Co-ferrite particles with the mean particle size of 50 $\AA$ were produced at pH 12 after adjusting the ratio of Fe$^{3+}$Co$^{2+}$=7/3(wt%) and Fe-Co particles with the mean particle size of 94 $\AA$ were produced by reducing the Co-ferrite particle with H$_2$at the temperature of 50$0^{\circ}C$. After triple adsorption of oleic acid dodecyl benzene sulfonate(D.B.S.) and tetra methyl ammonium(T.M.A.) ions on the surface of Fe-Co particles Fe-Co hydrophilic magnetic fluid was produced by dispersing the Fe-Co particles in ethylene glycol solution. The magnetization of the Fe-Co hydrophilic magnetic fluid increased with increasing the Fe-Co concentration. The magnetic fluid containing 70% (g/cc) Fe-Co showed 73 emu/g in magnetization at the magnetic intensity of 10 kOe.kOe.e.