• Journal of the Korean Magnetics Society
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• v.10 no.6
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• pp.269-273
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• 2000

Fe-l7Cr-2M(M=Si, Nb, Mo) alloy powder was prepared by plasma electrode rotating atomizer and than the alloy powder was formed and sintered. The particle shape of the Fe-l7Cr-2M(M=Si, Nb, Mo) alloy power is spherical. The saturation magnetization of the sintered Fe-17Cr-2Mo and Fe-l7Cr-2Nb alloy are 155 emu/g. The saturation magnetization of the sintered Fe-l7Cr-2Si alloy is less than that of the sintered Fe-l7Cr-2Mo and Fe-l7Cr-2Nb alloy. The amplitude relative permeability of the sintered Fe-l7Cr-2M(M=Si, Nb, Mo) alloy has the maximum value in the range of 3∼5 Oe applied field at forming pressure 12 ton/cm$^2$, sintering temperature 1200$^{\circ}C$, and frequency 1 kHz. Power loss of the sintered Fe-l7Cr-2Nb alloy is 40 mW/cc at applied field, H$\sub$a/=5 Oe, and frequency, f=1 kHz. The power loss of the sintered Fe-l7Cr-2Nb alloy is a half of that of the sintered Fe-l7Cr-2Si and Fe-l7Cr-2Mo alloy.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.608-613
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• 2011

Nanopowders of Mo, Ti and Si were made by high-energy ball milling. A dense nanostructured $(Ti,Mo)Si_2$ compound was sintered by the pulsed current activated combustion method within two minutes from mechanically activated powder of Mo, Ti and Si. A highly dense $(Ti,Mo)Si_2$ compound was produced under simultaneous application of 80 MPa pressure and a pulsed current. The mechanical properties and micorostructure were investigated. The hardness and fracture toughness of the $(Ti,Mo)Si_2$ were $1030kg/mm^2$ and $4.9MPa{\cdot}m^{1/2}$, respectively. The mechanical properties were higher than monolithic $TiSi_2$.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.938-944
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• 1998

$MoSi_2$/W composites were fabricated by vacuum hot press at $1600^{\circ}C$ under 30MPa for 3 hrs. The effects of the amount of tungsten in the composites was explained in terms of the microstructure and mechanical properties. Although tungsten was mainly substituted to Mo atoms forming a complete solid solution of (Mo.W).Si, (x= 1, 5, y=2, 3). the grain size of composites became smaller with the increase of tungsten added. Vickers hardness was increased with the increase of tungsten content due to the solid-solution hardening. On the other hand, toughness of composites decreased sharply by increasing the amount of tungsten. Optimum tungsten amount was determined to be a 10 vol% of composite. Indentation fracture toughness was calculated to be 4.5MPa\sqrt{m}$ in this composites, compared with $2.7MPa\sqrt{m}$ in pure $MoSi_2$.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.823-829
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• 2000

[ $Nb/MoSi_2$ ]laminate composites have been successfully fabricated by hot pressing in a graphite mould. Lamination of Nb foil and $MoSi_2$ layer showed a sufficient improvement in the absorbed impact energy compared to that of monolithic $MoSi_2$ material. The impact value of $Nb/MoSi_2$ laminate composites obviously is reduced when sintered at temperatures higher than 1523K, even if the composite density contributing to impact load increased along with fabricating temperatures. Impact value of laminate composites was also drastically decreased with the growth of reaction layer after the heat treatment. However, it was effective to increase the pressure at the same sintering temperature for the improvement of the impact value.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.43-43
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• 2001

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.115-118
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• 1999

Carbon composites with $MoSi_2$ dispersion were prepared by hot-pressing at $1700^{\circ}C$ under 30 MPa for 1 h using polysilazance as binding material. The composites consisted of C, $Mo_{4.8}Si_3C_{0.6}$ and SiC. Bulk density and porosity of the carbon composites with 10 vol% $MoSi_2$ was 1.8g.$\textrm{cm}^{-3}$ and 34%, respectively. This composite was oxidized about 0.05mm from the surface of the carbon composite after oxidation test at $1500^{\circ}C$ for 10h in air. Formation of the $SiO_2$ glass layer was observed by SEM. When this composite suffered damage in the coating layer, it had hardly farther oxidation because of its self-repairing property. The composite prepared in this study indicated good oxidation resistance.

• Journal of Hydrogen and New Energy
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• v.26 no.6
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• pp.524-531
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• 2015

To improve the electrochemical and mechanical characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK). The SPEEK organic-inorganic blended composite membranes were prepared by sol-gel casting method. It was loaded with the highly dispersed ceria and cesium-substituted molybdosilicic acid (Cs-MoSiA) and 1,4-diiodobutane which was cross-linking agent contents of $10{\mu}L$. Cs-MoSiA was added to increase proton conductivity. Ceria ($CeO_2$) was used as a free radical scavenger which degrade the membrane in polymer electrolyte membrane water elctrolysis (PEMWE). In conclusion, CL-SPEEK/Cs-MoSiA/Ceria 1% composite membrane showed high proton conductivity 0.2104 S/cm at $25^{\circ}C$ which was better than Nafion 117 membrane.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.29-34
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• 2002

[ $Nb/MoSi_2-ZrO_2$ ] laminate composites have been successfully fabricated by alternately stacking $MoSi_2-ZrO_2$ powder layer and Nb sheet, followed by hot pressing in a graphite mould. The fabricating parameters were selected as hot press temperatures. The instrumented Charpy impact test was carried out at the room temperature in order to investigate the relationship between impact properties and fabricating temperatures. The interfacial shear strength between $MoSi_2-ZrO_2$ and Nb, which is associated with the fabricating temperature and the growth of interfacial reaction layer, is also discussed. The plastic deformation of Nb sheet and the interfacial delamination were macroscopically observed. The $Nb/MoSi_2-ZrO_2$ laminate composites had the maximum impact value when fabricated at 1623K, accompanying the increase of fracture displacement and crack propagation energy. The interfacial shear strength of $Nb/MoSi_2-ZrO_2$ laminate composites increased with the growth of interfacial reaction layer, which resulted from the increase of fabricating temperature. there is an appropriate interfacial shear strength for the enhancement of impact value of $Nb/MoSi_2-ZrO_2$ laminate composites. A large increase of interfacial shear strength restrains the plastic deformation of Nb sheet.

• Composites Research
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• v.16 no.3
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• pp.41-48
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• 2003

In this work, the effect of molybdenum disilicide(MoSi$_2$) content on the impact properties of carbon-carbon composites(C/C composites) was investigated in the presence of MoSi$_2$. The content of MoSi$_2$ was varied in 0, 4, 12 and 20 wt% on the basis of resin matrix for anti-oxidation properties of the composites under high temperature. As a result, the composites made with MoSi$_2$ resulted in an increase of interfacial adhesion between fibers and matrix, which could improve the impact properties of the composites. Especially, 12 wt% Mosi$_2$ composites showed the highest impact properties in the present system. This was probably due to the existence of brittle-to-ductile transition(BDT) properties of MoSi$_2$ in the vicinity of 90$0^{\circ}C$, resulting from increasing the interfacial adhesion force among fibers, filler, and matrix in the composites.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.525-529
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• 2017

Molybdenum oxide ($MoO_3$) offers pivotal advantages for high optical transparency and low light reflection. Considering device fabrication, n-type $MoO_3$ semiconductor can spontaneously establish a junction with p-type Si. Since the energy bandgap of Si is 1.12 eV, a maximum photon wavelength of around 1,100 nm is required to initiate effective photoelectric reaction. However, the utilization of infrared photons is very limited for Si photonics. Hence, to enhance the Si photoelectric devices, we applied the wide energy bandgap $MoO_3$ (3.7 eV) top-layer onto Si. Using a large-scale production method, a wafer-scale $MoO_3$ device was fabricated with a highly crystalline structure. The $MoO_3/p-Si$ heterojunction device provides distinct photoresponses for long wavelength photons at 900 nm and 1,100 nm with extremely fast response times: rise time of 65.69 ms and fall time of 71.82 ms. We demonstrate the high-performing $MoO_3/p-Si$ infrared photodetector and provide a design scheme for the extension of Si for the utilization of long-wavelength light.