• Title, Summary, Keyword: Fe50Cr50

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Electromagnetic Wave Absorbing Properties of FeSiCr and Fe50Ni Flaky Powder-Polymer Composite Sheet (FeSiCr에 Fe50Ni가 첨가된 폴리머 복합 시트의 전자파 흡수 특성)

  • Lee, Seok-Moon;Kim, Sang-Mun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.7
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    • pp.462-467
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    • 2014
  • In this paper, we studied the magnetic composite sheets for electromagnetic wave noise absorber of quasi-microwave band by using soft magnetic FeSiCr and Fe50Ni flakes with the thickness of about $1{\mu}m$ and polymer. The magnetic hysteresis curve including saturation magnetization and residual magnetization and the complex permeability characteristics of the composite sheets were investigated to clarify the mixing effect on electromagnetic wave absorption properties. The saturation magnetization was decreased about 10% while the residual magnetization was increased about 15% and the real parts of complex permeability at below 500 MHz were increased 0.6~4 while those values at above 500 MHz were decreased 0.4~2.5 according to the change of contents of FeSiCr and Fe50Ni powders. As a result, the reflection loss can be moved to the lower frequency from 2~3 GHz to 1~1.5 GHz as the contents of Fe50Ni flaky powder into FeSiCr flaky powder was increased up to 50%.

Structural and Magnetic Properties of Fe50Cr50 Alloys Prepared by Mechanical Alloying Method

  • Yang, Dong-Seok;Park, Ji-Yeon;Yoo, Yong-Goo;Kim, Kyeong-Sup;Yu, Seong-Cho
    • Journal of Magnetics
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    • v.15 no.3
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    • pp.108-111
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    • 2010
  • Fe50Cr50 metastable alloys were prepared by the mechanical alloying method with milling periods of 1, 2, 4, 6, 12 and 24 hours, respectively. The structural evolution was analyzed by the extended x-ray absorption fine structure (EXAFS). In this work, the EXAFS analysis provided the local structural information around Fe central atom. The saturation magnetization was also measured by VSM. The magnetization decreased as the process mechanical alloying progressed. The magnetic property was related to the local structural variation as a function of processing time. The analysis showed that the diffusion Cr atoms into Fe clusters caused the reduction of magnetization. EXAFS analysis exhibited that the local ordering of magnetic atoms caused the magnetic ordering. Also, EXAFS analysis showed that the long range order of Fe atoms was destroyed completely in 24 hour milling.

Synthesis of Cobalt Oxide Free Black Color Spinel Pigment (CoO가 첨가되지 않은 스피넬계 흑색안료의 합성)

  • Kim, Jun-Ho;Lee, Seong-Ho;Suh, Man-Chul;Lee, Byung-Ha
    • Journal of the Korean Ceramic Society
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    • v.44 no.11
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    • pp.639-644
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    • 2007
  • Spinel pigments, developing black color in high temperature glazes at oxidation or reduction atmosphere, without CoO because of its high price were synthesized by solid solution method. Ten mixed compositions consisted of NiO, MnO, $Fe_2O_3 and $Mn_2O_3$ were fired at $1250^{\circ}C$ for 1h. The resulting pigments were characterized by using XRD, FT-IR, SEM and UV-vis spectrometer. Structure of the pigments are spinel and particles' shape are spherical or cubic. Glazed tiles containing 5 wt% pigments were fired at $1260^{\circ}C$ and $1240^{\circ}C$ in reduction atmosphere. Color in glazes were analyzed by UV-vis spectrometer. Colors of NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole% in lime glaze showed black in oxidation, in reduction NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.55{\cdot}Mn_2O_3$ 0.0125 mole% showed black. In case of lime-barium glaze, NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.975 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black color in oxidation and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.725 MnO $0.275{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black one in reduction.

Corrosion of Fe-(8.5~36.9) wt% Cr Alloys at 600~800℃ in (N2, H2S, H2O)-Mixed Gases (Fe-(8.5~36.9) wt% Cr합금의 600~800℃, (N2,H2S,수증기)-혼합 가스분위기에서의 부식)

  • Kim, Min Jung;Lee, Dong Bok
    • Korean Journal of Metals and Materials
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    • v.50 no.3
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    • pp.218-223
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    • 2012
  • Fe-(8.5, 18.5, 28.3, 36.9) wt% Cr alloys were corroded between 600 and $800^{\circ}C$ for up to 70 h in a 1 atm gas mixture that consisted of 0.0242 atm of $H_2S$, 0.031 atm of water vapor, and 0.9448 atm of nitrogen gas. Their corrosion resistance increased with an increment in the Cr content. The Fe-8.5%Cr alloy corroded fast, forming thick, fragile, nonadherent scales that consisted primarily of an outer FeS layer and an inner (Fe, Cr, O, S)-mixed layer. The outer FeS layer grew into the air by the outward diffusion of $Fe^{2+}$ ions, whereas the inner mixed layer grew by the inward diffusion of oxygen and sulfur ions. At the interface of the outer and inner scales, voids developed and cracking occurred. The Fe-(18.5, 28.3, 36.9)% Cr alloys displayed much better corrosion resistance than the Fe-8.5Cr alloy, because thin $Cr_2O_3$ or $Cr_2S_3$ scales formed.

Giant Magnetoresistance of Antiferromagnetic Cr-Al based Multilayer Spin-Valve with Anti-Corrosion and Thermal Stability (내열 내식용 Cr-Al반강자성계 스핀밸브막의 거대자기저항 효과)

  • 김병수;이성훈;이찬규
    • Journal of the Korean Magnetics Society
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    • v.8 no.6
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    • pp.362-368
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    • 1998
  • The magnetic properties, thermal stability and anti-corrosion properties of $Cr_86Al_14$ spin valves multilayers were studied. It was found that the magnetic properties of $Cr_86Al_14$ spin valves depend on the thickness of antiferromagnetic, ferromagnetic and non-ferromagnetic layers. Exchange coupled field ($H_{ex}$) and magnetoresistance ratio (%) showed the largest value of 20 Oe, 2 % in $glass/Cr_{86}Al_{14}(600 $\AA$)/Ni_{81}Fe_{19}(50$\AA$)/Cu(40 $\AA$)/Ni_{81}Fe_{19}(40 $\AA$)$ spin valves. The $H_{ex}$ MR ratios (%) of CrAl and FeMn spin valves were decreased with increasing annealing temperatures and were lost at 150 $^{\circ}C$, 250 $^{\circ}C$ respectively. Based on these result, it was elucidated that CrAl is more thermally stable than FeMn. It was also shown that there was no change of $H_{ex}$ MR ratios in CrAl, while FeMn was changed and lost 15 days later in corrosion resistance test under 35 $^{\circ}C$, 90 % humidity condition. FeMn was found to be pitted and peeled off 15 days later by SEM micrographic analysis.

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Phase Transition of As-Milled and Annealed CrCuFeMnNi High-Entropy Alloy Powder

  • Zhao, Rui-Feng;Ren, Bo;Zhang, Guo-Peng;Liu, Zhong-Xia;Zhang, Jian-Jian
    • Nano
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    • v.13 no.9
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    • pp.1850100.1-1850100.11
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    • 2018
  • The CrCuFeMnNi high entropy alloy (HEA) powder was synthesized by mechanical alloying. The effects of milling time and subsequent annealing on the structure evolution, thermostability and magnetic property were investigated. After 50 h of milling, the CrCuFeMnNi HEA powder consisted of a major FCC phase and a small amount of BCC phase. The crystallite size and strain lattice of 50 h-ball-milled CrCuFeMnNi HEA powder were 12 nm and 1.02%, respectively. The powder exhibited refined morphology and excellent chemical homogeneity. The supersaturated solid solution structure of the as-milled HEA powder transformed into FCC1, FCC2, a small amount of BCC and ${\rho}$ phase in annealed state. Most of the BCC phase decomposed into FCC (mainly FCC2 phase) and ${\rho}$ phases, and the dynamic phase transition was almost in equilibrium at $900^{\circ}C$. The saturated magnetization and coercivity force of the 50 h-ball-milled CrCuFeMnNi HEA powder were respectively 16.1 emu/g and 56.2 Oe.

Cyclic Oxidation Behavior of Fe-Cr-Al Joint Brazed with Nickel-Base Filler Metal (Ni계 합금으로 브레이징된 Fe-Cr-Al 합금 접합부의 주기산화거동)

  • Mun, Byeong-Gi;Choe, Cheol-Jin;Park, Won-Uk
    • 연구논문집
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    • pp.141-149
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    • 1999
  • Brazing of Fe-Cr-Al alloy was carried out at $1200^{\circ}C$ in vacuum furnace using nickel-based filler metals : BNi-5 powder(Ni-Cr-Si-Fe base alloy} and MBF-50 foil (Ni-Cr-Si-B). The effect of boron content on the stability of oxide scale on the brazed joint was investigated by means of cyclic oxidation test performed at $1050^{\circ}C$ and $1200^{\circ}C$. Apparently, the joints brazed with MBF-50 containing boron showed relatively stable oxidation rates compared to boron-free BNi-5 at both temperatures. However, it was considered that the slower weight loss of MBF-50 brazed specimen wasn’t resulted from the low oxidation rate but from the spallation of oxide layer. The oxide layer consisted of thick spinel oxide on the surface and $Al_2 O_3$ internal oxide layer along the interface between mother alloy and braze, the mother alloy was also eroded seriously by the formation of spinel oxides such as $FeCr_2 O_4$ and $NiCr_2 O_4$ on the surface, likely to be induced by the change of oxide forming mechanism due to diffusion of boron from the braze. On the contrary, the joint brazed with BNi-5 showed the good oxidation resistance during the cyclic oxidation test. It seems that the oxidation can be retarded by the formation of stable $Al_2 O_3$ layer at the surface.

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Corrosion of Fe-(10~40)%Cr Steels in Na2SO4 Salts at 800~900℃ (Fe-(10~40%)Cr강의 800~900℃에서의 Na2SO4 염에서의 부식)

  • Kim, Seul Ki;Lee, Jae Ho;Lee, Dong Bok
    • Korean Journal of Metals and Materials
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    • v.50 no.5
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    • pp.361-368
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    • 2012
  • Fe-(10, 20, 30, 40) wt%Cr alloys were corroded in $Na_2SO_4$ salts ($m.p.=884^{\circ}C$) at $800{\sim}900^{\circ}C$ for 3-300 hrs. Their corrosion resistance increased with an increase in Cr content owing to the formation of slowly growing $Cr_2O_3$. During corrosion, $Na_2SO_4$ dissociated and reacted with the alloys to form $Cr_2O_3$ and $Fe_2O_3$. Since $Fe_2O_3$ dissolved fast into the salts, most of the scales consisted primarily of $Cr_2O_3$. Inside the scale, a small amount of sulfides also existed. The oxidation, dissolution and detachment of the formed scales occurred significantly.

High Temperature Oxidation Behavior of Fe-14Cr Ferritic Oxide Dispersion Strengthened Steels Manufactured by Mechanical Alloying Process (기계적 합금화 공정으로 제조된 Fe-14Cr Ferritic 산화물 분산 강화(ODS) 합금 강의 고온 산화 거동)

  • Kim, Young-Kyun;Park, Jong-Kwan;Kim, Hwi-Jun;Kong, Man-Sik;Lee, Kee-Ahn
    • Journal of Korean Powder Metallurgy Institute
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    • v.24 no.2
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    • pp.133-140
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    • 2017
  • This study investigates the oxidation properties of Fe-14Cr ferritic oxide-dispersion-strengthened (ODS) steel at various high temperatures (900, 1000, and $1100^{\circ}C$ for 24 h). The initial microstructure shows that no clear structural change occurs even under high-temperature heat treatment, and the average measured grain size is 0.4 and $1.1{\mu}m$ for the as-fabricated and heat-treated specimens, respectively. Y-Ti-O nanoclusters 10-50 nm in size are observed. High-temperature oxidation results show that the weight increases by 0.27 and $0.29mg/cm^2$ for the as-fabricated and heat-treated ($900^{\circ}C$) specimens, and by 0.47 and $0.50mg/cm^2$ for the as-fabricated and heat-treated ($1000^{\circ}C$) specimens, respectively. Further, after 24 h oxidation tests, the weight increases by 56.50 and $100.60mg/cm^2$ for the as-fabricated and heat-treated ($1100^{\circ}C$) specimens, respectively; the latter increase is approximately 100 times higher than that at $1000^{\circ}C$. Observation of the surface after the oxidation test shows that $Cr_2O_3$ is the main oxide on a specimen tested at $1000^{\circ}C$, whereas $Fe_2O_3$ and $Fe_3O_4$ phases also form on a specimen tested at $1100^{\circ}C$, where the weight increases rapidly. The high-temperature oxidation behavior of Fe-14Cr ODS steel is confirmed to be dominated by changes in the $Cr_2O_3$ layer and generation of Fe-based oxides through evaporation.

Effect of Sulfur on the High-temperature Oxidation of Fe-34.4Cr-14.5Ni-2.5Mo-0.4W-0.4Mn-0.5Si Alloys (Fe-34.4Cr-14.5Ni-2.5Mo-0.4W-0.4Mn-0.5Si 합금의 고온 산화에 미치는 S의 영향)

  • Lee, Dong Bok;Lee, Kyong-Hwan;Bae, Geun Soo;Cho, Gyu Chul;Jung, Jae Ok;Kim, Min Jung
    • Journal of the Korean institute of surface engineering
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    • v.50 no.5
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    • pp.386-391
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    • 2017
  • Two kinds of steels whose compositions were Fe-34.4Cr-14.5Ni-2.5Mo-0.4W-0.4Mn-0.5Si-(0.009 or 0.35)S (wt.%) were centrifugally cast, and oxidized at $900^{\circ}C$ for 50-350 h in order to find the effect of sulfur on the high-temperature oxidation of Fe-34.4Cr-14.5Ni-2.5Mo-0.4W-0.4Mn-0.5Si-(0.009 or 0.35)S (wt.%) alloys. These alloys formed oxide scales that consisted primarily of $Cr_2O_3$ as the major oxide and $Cr_2MnO_4$ as the minor one through preferential oxidation of Cr and Mn. They additionally formed $SiO_2$ particles around the scale/alloy interface as well as inside the matrices. The high affinity of Mn with S led to the formation of scattered MnS inclusions particularly in the 0.35S-containing cast alloy. Sulfur was harmful to the oxidation resistance, because it deteriorated the scale/alloy adherence so as to accerelate the adherence and compactness of the formed scales.