• Korean Journal of Materials Research
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• v.16 no.1
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• pp.5-10
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• 2006

This study was performed to investigate the characteristics of the synthesized powder type ferro materials for wear resistant hardfacing. The powder type filler materials were made from ferro Cr and ferro Mn. Those ferro materials are two types, such as high carbon and low carbon contained. The alloy composed of high carbon ferro Cr and high carbon ferro Mn exhibited the best properties in terms of microstructure and hardeness for wear characteristics. Further, the alloys produced by the synthesized powders and wire type filler, were also evaluated in terms of microstructures and microhardness measurements. The results indicated that the synthesized powders displayed reasonable properties compared to commercial grade materials. The hardness value of the alloy produced by the synthesized powders were approached about 90% of the commercial grade's hardness. The hardness values of the alloys closely depended on the amount of the dissolution of the ferro Cr, the hardness and the volume of the eutectic phase.

• Resources Recycling
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• v.21 no.3
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• pp.21-27
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• 2012

In order to make high-purity ferro-manganese from $Mn_3O_4$ dust, the application of aluminothermy process to the reduction of $Mn_3O_4$ dust was investigated in previous work. The result showed the fact that can be obtained high purity ferro-manganese which have over about 93% of manganese content and lower impurities such as C, P, S than those of KS D3712 specification. The addition of silicon powder instead of aluminum powder was investigated as reductant in the thermite reaction process of $Mn_3O_4$ dust in this work because its production cost is lower than that of aluminum powder. In case of addition of silicon powder only as reductant, the experimental result showed the unstable ignition and no thermite reaction of mixture, but in case of simultaneous addition of silicon and aluminum powders as reductant, showed the fact that can be obtained high purity ferro-manganese which have much low content of impurities such as C, P, S component.

• Journal of the Korean Applied Science and Technology
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• v.28 no.2
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• pp.135-139
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• 2011

In order to make high-purity ferro-manganese from $Mn_3O_4$ waste dust, the application of aluminothermite process to the reduction of the waste dust was investigated. The mixture from $Mn_3O_4$ dust as metallic source and Al metal powder as the reductant ignited, and reduced with an extremely intense exothermic reaction. The rapid propagation of the aluminothermite reaction occurred spontaneously and stably by ignition of the mixture. The Manganese having some alloy elements emerged as liquids due to the high temperatures reached up to about $2,500^{\circ}C$ and separated from the liquid by their differences of specific gravity. The result of thermite reaction showed the fact that can be obtained high purity ferro-manganese which have over about 90% of manganese content and lower impurities such as C, P, S than those of KS D3712 specification. The recovery of manganese from $Mn_3O_4$ dust was lower level of about 65% than about 75% from manganese ore by electric furnace process, that is due to spatter loss because of its extremely intense thermite reaction. But it will be improved by the process designed to provide CaO as the cooler or to use the Al metal powder having larger particle size distribution.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.71-77
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• 2013

Aluminium powder as reductant in aluminothermy process needs a fine particle size under 200 mesh, but it is not easy economically to make that because of its high ductility and powder production cost. In order to reduce the production cost of fine aluminum powder as reductant of $Mn_3O_4$ waste dust, therefore, the properties of aluminium alloy powder were investigated. Aluminium alloy ingot containing large amount of manganese can be crushed easily because of its intermetallic compounds having brittle properties. The manganese is also main element in ferro-manganese. We can obtain economically Al-15%Mn alloy powder by mechanical comminution process. And the result of thermite reaction using Al-15% Mn alloy powder instead of pure Al powder showed the fact that can be obtained the ferro-manganese which have a high purity in case of using pure aluminium powder as reductant. The recovery of manganese from $Mn_3O_4$ waste dust with Al-15%Mn alloy powder was higher level of about 70% than about 65% in case of using aluminium powder, that is due to lower spatter loss.

• Journal of Magnetics
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• v.5 no.1
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• pp.9-12
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• 2000

Electron spin resonance and magnetization measurements were carried out on $La_0.7Ca_0.3MnO_3$ in the ferromagnetic as well as paramagnetic phases. Evidence of an inhomogeneous magnetic structure, consisting of ferro-magnetic microregions embedded in an antiferromagnetic matrix near $T_c$, as well as similar local magnetic structures above and below $T_c$, were found.

• Resources Recycling
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• v.9 no.4
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• pp.16-27
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• 2000

In order to produce raw material powder of advanced magnetic material by spray roasting process, newly modified spray roasting system was developed in this work. In this spray roasting system, raw material solution was effectively atomized and sprayed into the reaction furnace. Also, uniform temperature distribution inside reaction furnace made thermal decomposition process fully completed, and produced powder was effectively collected in cyclone and bag filter. This system equipped with apparatus which can purify hazard produced gas. In this study complex acid solution was prepared by dissolution of mill scale and ferro-Mn into the acid solution, and the pH of this complex acid solution was controlled about to 4. It was conformed that mill scale and ferro-Mn containing a lot of impurities such as $SiO_2$, P and Al could be used as raw material by reducing the impurities content of complex acid solution below 20 ppm. Complex oxide powder of Fe-Mn system was produced by spraying purified complex acid solution into the spray roaster through nozzle, and the variations of produced powder characters were studied by changing he reaction conditions such as reaction temperature, the injection velocity of solution and air, nozzle tip size and concentration of solution. The morphology of produced powder had spherical shape under the most experimental conditions, and concentration of solution. The morphology of produced powder has spherical shape under the most experimental conditions, and the composition and the particle size distribution were almost uniform, which tells the excellence of this spray roasting system. The grain size of most produced powder was below 100 nm. From the above results, it will be possible to produce ultra fine oxide powder from the chloride of Fe, Mn, Ni, Cu and rare earth by using this spray roasting system, and also to produce ultra fine pure metal powder by changing reaction atmosphere.

• Resources Recycling
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• v.7 no.4
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• pp.64-75
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• 1998

The purpose of this study is to produce high putity composite powder composed of Fe-oxide, Mn-oxide and Mn-ferrite having superior homogencity in composition and particle size distribution by co-roasting process. Binary component metal (Fe, Mn) chloride solutions were produced by dissolving mill scale and ferro-mangancse alloy in hydrochloric acid. These chloride solutions contained the impurities such as SiO$_{2}$, P, Al, Ca and Na, which were originated from the Fe/Mn source materials. The neutralization and polymeric coagulant method were adoped to refine the hydrochloric liquor. When pH is far below the isoelectric point (pH 2-3), the SiO$_{2}$ was the most effectively reduced element, while other impurities remained unchanged. By increasing pH above 3, most of the impurities could be reduced effectively due to the coprecipitation reaction. The polymeric coagulants such as poly vinyl alcohol, resin amine and ammonium molybdate were found to have no effect on the spray roaster designed by the authors. The produced oxide powders were confirmed to be mixtures of Fe-oxide, Mn-oxide and mn-ferrite. the powders were homogeneously mixed and the particle size increased sleeply with increasing co-roasting temperature.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.4
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• pp.48-58
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• 1988

This study was undertaken to observe the formation behavior of ferro- magnetic phase in Mn-Al-Cu Alloys. The alloy selected for this investigation was 70% Mn-29% Al-1% Cu. This pre-allyed pig was prepared to the cylinderical castings using an Induction furnace after homogenizing at $1100^{\circ}C$ for 2hr, the specimens were cooled by cooling methods. Subwequent isothermal heat treatments were followed at $550^{\circ}C$ for various periods of time at predetermined(1-1000min). The formation behavior of ferromagnetic phase was investigated by measurements of magnetic properties of the specimens at each stage of heat treatment, and optical microscopic esamination and X-Ray diffraction analyses were also employed. By this basic experimental results, the conclusions are as follows 1) In order to obtain much amount of ferromagnetic phase, the optimum average cooling rate was about 7.35-$16.4^{\circ}C$/sec($1100^{\circ}C$-$600^{\circ}C$). 2) We verified the decomposition of {\tau} phase to {\beta} -Mn and {\gamma} , as the specimens were homogenized at $1100^{\circ}C$ for 12hr, then heat-treased at $550^{\circ}C$ for 1-1000min. 3) A condition of optimum heat treatments in Mn-Al-Cu permanent mag-netic alloys showed that after homogenizing at $1100^{\circ}C$ for 2hr, the speciments were cooled in air or furnace(A) and subsequent heat treatments at $550^{\circ}C$ for 1-30min. The maximum magnetic properties were measured as follows: Air cooling; Br=1200(Gause), bHc=100(oe), (BH)max=0.07(MGOe) Furnace cooling(A);Br=950(Gauss), bhe=80(Oe), (BH)max=0.05(MGOe)

• Investigative Magnetic Resonance Imaging
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• v.19 no.2
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• pp.76-87
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• 2015

Purpose: There is an ongoing search for a stent material that produces a reduced susceptibility artifact. This study evaluated the effect of manganese (Mn) content on the MRI susceptibility artifact of ferrous-manganese (Fe-Mn) alloys, and investigated the correlation between MRI findings and measurements of Fe-Mn microstructure on X-ray diffraction (XRD). Materials and Methods: Fe-Mn binary alloys were prepared with Mn contents varying from 10% to 35% by weight (i.e., 10%, 15%, 20%, 25%, 30%, and 35%; designated as Fe-10Mn, Fe-15Mn, Fe-20Mn, Fe-25Mn, Fe-30Mn, and Fe-35Mn, respectively), and their microstructure was evaluated using XRD. Three-dimensional spoiled gradient echo sequences of cylindrical specimens were obtained in parallel and perpendicular to the static magnetic field (B0). In addition, T1-weighted spin echo, T2-weighted fast spin echo, and $T2^*$weighted gradient echo images were obtained. The size of the low-intensity area on MRI was measured for each of the Fe-Mn binary alloys prepared. Results: Three phases of ${\alpha}^{\prime}$-martensite, ${\gamma}$-austenite, and ${\varepsilon}$-martensite were seen on XRD, and their composition changed from ${\alpha}^{\prime}$-martensite to ${\gamma}$-austenite and/or ${\varepsilon}$-martensite, with increasing Mn content. The Fe-10Mn and Fe-15Mn specimens comprised ${\alpha}^{\prime}$-martensite, the Fe-20Mn and Fe-25Mn specimens comprised ${\gamma}+{\varepsilon}$ phases, and the Fe-30Mn and Fe-35Mn specimens exhibited a single ${\gamma}$ phase. The size of the low-intensity areas of Fe-Mn on MRI decreased relative to its microstructure on XRD with increasing Mn content. Conclusion: Based on these findings, proper conditioning of the Mn content in Fe-Mn alloys will improve its visibility on MR angiography, and a Mn content of more than 25% is recommended to reduce the magnetic susceptibility artifacts on MRI. A reduced artifact of Fe-Mn alloys on MRI is closely related to the paramagnetic constitution of ${\gamma}$-austenite and/or ${\varepsilon}$-martensite.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.1
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• pp.12-15
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• 2002

The physical properties, including magneto-optical and transport ones, of Ni$_2$MnG$_2$ alloy in the martensitic and austenitic states were investigated. The dependence of the temperature coefficient of resistivity on temperature shows kinks at the structural and ferro-para magnetic transitions. Electron-magnon and electron-phonon scattering are analyzed to be the dominant scattering mechanisms of the Ni$_2$MnG$_2$ alloy in the martensitic and austenitic states, respectively. The experimental real parts of the off-diagonal components of the dielectric function present two sharp peaks, one at 1.9 eV and the other at 3.2 eV, and a broad shoulder at 3.5 eV, all are identified by the band-structure calculations. These peak positions are coincident with those in the corresponding optical-conductivity spectrum, which is thought to originate from the single-spin state in Ni$_2$MnG$_2$ alloy.