• 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.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.288-297
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• 1994

In this study, lattice parameter, binding energy and microstructures of TiC layer according to the addition of Fe, Cr were investigated in the reactive deposition coating. From the results, the lattice parameters of the TiC layers by using ferro-titanium as a precursor were 4.329~4.339A but the lattice parameters of the TiC layers formed by ferro-titanium and ferro-chromium decreased to 4.316~4.330A. The hardness of the former's was HV(100g) 3,000~3,400kg/mm and the hardness of the latter's was HV (100g) 3,800~3,900. But, regardless of Cr and Fe, the binding energy of TiC layers were 454.75 eV for $Ti2p_{3/2}$ and were 281.85 eV for Cls. Meanwhile, the TiC layers were densified by addition of Fe, Cr and internal defects were reduced Therefore. it can be concluded that the remarkable hardness increment was obtained by the improvement of microstructures of TiC rather than the increase of bond strength or Peierls stress.

• Korean Journal of Materials Research
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• v.27 no.5
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• pp.263-269
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• 2017

Fe-Si-Cr ferroalloy is predominantly produced by carbothermic reduction. In this study, silicothermic and carbothermic mixed reduction of chromite ore to produce Fe-Si-Cr alloy is suggested. As reductants, silicon and silicon carbide are evaluated by thermochemical calculations, which prove that silicon carbide can be applied as a raw material. Considering the critical temperature of the change from the carbide to the metallic form of chromium, thereduction experiments were carried out. In these high temperature reactions, silicon and silicon carbide act as effective reductants to produce Fe-Si-Cr ferroalloy. However, at temperatures lower than the critical temperature, silicon carbide shows a slow reaction rate for reducing chromite ore. For the proper implementation of a commercial process that uses silicon carbide reductants, the operation temperature should be kept above the critical temperature. Using equilibrium calculations for chromite ore reduction with silicon and silicon carbide, the compositions of reacted metal and slag were successfully predicted. Therefore, the mass balance of the silicothermic and carbothermic mixed reduction of chromite ore can be proposed based on the calculations and the experimental results.

• Economic and Environmental Geology
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• v.27 no.1
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• pp.29-39
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• 1994

Gabbroic rocks in which titanomagnetite orebodies are embedded were emplaced in Precambrian metasedimentary rocks. Hornblende K-Ar ages for equigranula and gneissic gabbros were obtained to be $1021.8{\pm}14.5$ Ma and $1468.4{\pm}20.8$ Ma, respectively. Biotite-granite has an age of 116.4 Ma, which has corresponded to Daebo granite. Amphibole minerals of the gabbroic rock and the magnetite orebodies belong to calcic amphibole group such as ferroan pargasite, pargasite, and ferro-pargasite. The gabbroic rocks have unusually high content of $TiO_2$ ranging from 0.88 to 6.03 wt.% with an average value of 3.46 wt.% as compared to normal gabbroic rock with 1.32 wt.% in $TiO_2$. Incompatible elements such as Ba and Sr of the gabbros are negatively correlated with $SiO_2$. In contrast, Co and Cr have a positive correlation with $SiO_2$, suggesting a normal differentiation trend of gabbroic magma.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.297-302
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• 2022

We investigated the origin of magnetic behaviors induced by an asymmetric spin exchange interaction in Fe-site engineered lead iron niobate [Pb(Fe_1/2Nb_1/2)O₃, PFN], which exhibits a room-temperature multiferroicity. The magnitude of spin exchange interaction was regulated by the introduced transition metals with a distinct Bohr magneton, i.e., Cr, Co, and Ni. All compositions were found to have a single-phase perovskite structure keeping their ferroelectric order except for Cr introduction. We discovered that the incorporation of each transition metal imposes a distinct magnetic behavior on the lead iron niobate system; antiferro-, hard ferro-, and soft ferromagnetism for Cr, Co, and Ni, respectively. This indicates that orbital occupancy and interatomic distance play key roles in the determination of magnetic behavior rather than the magnitude of the individual Bohr magneton. Further investigations are planned, such as X-ray absorption spectroscopy, to clarify the origin of magnetic properties in this system.