• Carbon letters
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• v.4 no.2
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• pp.74-78
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• 2003

Four kinds of plasma blacks were prepared by plasma pyrolysis under various metallic catalysts coated on honeycomb, and investigated the catalytic effect on the characteristics of the plasma blacks prepared under plasma pyrolysis condition. Pt, Pt-Rh, and Pd catalysts were employed as active materials to prepare the plasma blacks. In the experimental range studied, the metallic catalysts influenced on surface area, particle size, surface oxygen content and electrical conductivity of the plasma blacks prepared. It was showed that more dense particle of plasma blacks were prepared under existence of metallic catalysts. Presence of the metallic catalyst reduces the electrical resistivity of plasma blacks due to the decrease in the amount of oxygen functional groups. The highest electrical conductivity of plasma black was observed in the Pt catalyst and then followed by those Pt-Rh, Pd and bare cordierite honeycomb.

• Journal of Powder Materials
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• v.14 no.3 s.62
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• pp.197-201
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• 2007

Bulk metallic glass (BMG) composite was fabricated by consolidation of milled metallic glass composite powders. The metallic glass composite powder was synthesized by a controlled milling process using the Cu-based metallic glass powder blended with 30 vol% Zr-based metallic glass powders. The milled composite powders showed a layered structure with three metallic phases, which is formed as a result of mechanical milling. By spark plasma sintering of milled metallic glass powders in the supercooled liquid region, a fully dense BMG composite was successfully synthesized.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.6
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• pp.1-9
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• 2022

This study introduces the calculation model of ionization composition and electrical conductivity for metallic plasma for practical application to modeling and simulation of modern electrical detonators. The present model includes the correction for non-ideality of dense plasma conditions which are expected in electrical explosion of bridge in detonators. The computational results for copper plasma show favorable agreement with experimental data for a wide range of plasma temperature and high density conditions and the model is proper for detonator modeling with good prediction accuracy.

• Journal of Powder Materials
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• v.30 no.1
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• pp.41-46
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• 2023

In this study, an Al₈₂Ni₇Co₃Y₈ (at%) bulk metallic glass is fabricated using gas-atomized Al₈₂Ni₇Co₃Y₈ metallic glass powder and subsequent spark plasma sintering (SPS). The effect of powder size on the consolidation of bulk metallic glass is considered by dividing it into 5 ㎛ or less and 20-45 ㎛. The sintered Al₈₂Ni₇Co₃Y₈ bulk metallic glasses exhibit crystallization behavior and crystallization enthalpy similar to those of the Al₈₂Ni₇Co₃Y₈ powder with 5 ㎛ or less and it is confirmed that no crystallization occurred during the sintering process. From these results, we conclude that the Z-position-controlled spark plasma sintering process, using superplastic deformation by viscous flow in the supercooled liquid-phase region of amorphous powder, is an effective process for manufacturing bulk metallic glass.

• Journal of Powder Materials
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• v.14 no.6
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• pp.405-409
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• 2007

The Cu-based bulk metallic glass (BMG) composites containing Zr-based metallic glass phase have been consolidated by spark plasma sintering using the mixture of Cu-based and Zr-based metallic glass powders in their overlapped supercooled liquid region. The Zr-based metallic glass phases are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation process. The successful consolidation of BMG composites with dual amorphous phases was corresponding to the sound viscous flow of the two kinds of metallic glass powders in their overlapped supercooled liquid region.

• Journal of Powder Materials
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• v.20 no.1
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• pp.33-36
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• 2013

A bulk metallic glass-forming alloy, $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ metallic glass powders was used for good commercial availability and good formability in supercooled liquid region. In this study, the Ni-based metallic glass was synthesized using by high pressure gas atomized metallic glass powders. In order to create a bulk metallic glass sample, the $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ metallic glass powders with ball-milled Ni-based amorphous powder with 40%vol brass powder and Cu powder for 20 hours. The composite specimens were prepared by Spark Plasma Sintering for the precursor. The SPS was performed at supercooled liquid region of Ni-based metallic glass. The amorphous structure of the final sample was characterized by SEM, X-ray diffraction and DSC analysis.

• Journal of Powder Materials
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• v.15 no.4
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• pp.297-301
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• 2008

The Ni-based bulk metallic glass matrix composites were fabricated by spark plasma sintering of mixture of gas-atomized metallic glass powders and ductile brass powders. The successful consolidation of metallic glass matrix composite was achieved by strong bonding between metallic glass powders due to viscous flow deformation and lower stress of ductile brass powders in the supercooled liquid state during spark plasma sintering. The composite shows some macroscopic plasticity after yielding, which was obtained by introducing a ductile second brass phase in the Ni-based metallic glass matrix.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.246-252
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• 2016

In this paper, reduction of monostatic RCS by DBD plasma is measured. For the calibration of monostatic RCS, S-parameters of two metallic plate in different sizes are used and the result is within 0.4 dB error. Metallic plate is put behind DBD plasma generator for measuring reduction of monostatic RCS by DBD plasma. To prevent arc discharge between metallic plate and DBD plasma generator, measurement is progressed spacing the interval between metallic plate and DBD plasma generator. As a result, maximum reduction of monostatic RCS is about 3 dB at 7.4 GHz.

• Journal of Powder Materials
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• v.14 no.6
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• pp.399-404
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• 2007

The Cu-based bulk metallic glass (BMG) composite was fabricated by spark plasma sintering (SPS) using of gas-atomized metallic glass powders and ductile brass powders. No defect such as pores and cavities was observed at the interface between the brass powder and the metallic glass matrix, suggesting that the SPS process caused a severe viscous flow of the metallic glass and brass phases in the supercooled liquid region, resulting in a full densification. The BMG composites shows some macroscopic plasticity after yielding, although the levels of strength decreased.

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.504-509
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• 2009

The Zr-based bulk metallic glass matrix composites of a mixture of gas-atomized metallic glass powders and Fe-based nanostructured powders were fabricated by spark plasma sintering. The Fe-based nanostructured powders adopted for the enhancement of plasticity were well distributed in the matrix after consolidation, and the matrix remains as a fully amorphous phase. The successful consolidation of metallic glass matrix composite with high density was attributed to viscous flow in the supercooled liquid state during spark plasma sintering. Unlike other amorphous matrix composites, in which improved ductility could be obtained at the expense of their strength, the developed composite exhibited improvement both in strength and ductility. The ductility improvement in the composite was considered to be due to the formation of multiple shear bands under the presence of the Fe-based nanostructured particles.