Journal of Powder Materials

[Korean]
Research and Development of Hybrid Materials: Young-Keun Jeong, Myung-Chang Kang, Kwang-Ho Kim; J Korean Powder Metall Inst. 2007;14(1):1-7.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.001

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Effect of Casting Speed on Microstructure and Mechanical Properties of Al-Mg-Si/Al Hybrid Material by Duo-Casting
Sung Jin Park, Jun-Young Suh, Hee-Kwon Lee, Si Young Chang
Korean Journal of Materials Research.2020; 30(3): 111. CrossRef
Fabrication of Ultra Fine Grained Molybdenum and Mechanical Properties
Se-Hoon Kim, Young-Ik Seo, Dae-Gun Kim, Myung-Jin Suk, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(3): 235. CrossRef

[Korean]
The Effect of a CAM Treatment on the Sinterability of UO₂ Powder: Je-Sun Moon, S.H. Na, K.H. Kang, C.S. Park, K.C. Song; J Korean Powder Metall Inst. 2007;14(1):8-12.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.008

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Abstract PDF: The effect of a CAM (Continuous Attrition Mill) treatment on the sinterability of ex-ADU UO_2 powder was investigated. As the cycles of a CAM increased, the apparent density, specific surface area and O/U of the milled powder increased, but there particle sizes decreased. However the sintered density of the UO_2 pellet decreased as the cycles of the CAM increased. It is considered that the decrease of the sintered density is due to the formation of U_3O_8, which was produced by a CAM mechanism.

[Korean]
Texture and Mechanical Properties of Ni-W Alloy Tapes Fabricated from Powder Mother Billets: Min-Woo Kim, Byung-Hyuk Jun, Bong-Ki Ji, Kyu-Dong Jung, Chan-Joong Kim; J Korean Powder Metall Inst. 2007;14(1):13-18.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.013

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The mother Ni-W (1-5 wt.%) alloy billets for coated conductor substrate were fabricated by powder metallurgy process. The tensile test results for the sintered Ni-W rods showed the increase of mechanical strength and decrease of ductility with increasing W content due to the solid solution hardening. All the fracture surfaces of the tested specimens showed the typical ductile fracture mode of dimple rupture due to the local necking. The Ni-W alloy billets were made into tape by cold rolling. After the appropriate heat treatment for recrystallization, the brass texture formed by the cold rolling was converted to the complete cube texture. The in-plane and out of plane texture of the tapes estimated by x-ray pole figure were smaller than 9 degree and 7 degree, respectively. The effect of the W addition on the texture development seems not to be significant.

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Production of textured ribbons based on Ni–W paramagnetic alloys
V.A. Finkel
Functional Materials.2013; 20(1): 103. CrossRef

[Korean]
Synthesis of γ-Fe₂O₃ Nanoparticles by Low-pressure Ultrasonic Spraying: Chang-Woo Lee, Soon-Gil Kim, Yong-Ho Choa, Jai-Sung Lee; J Korean Powder Metall Inst. 2007;14(1):19-25.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.019

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Abstract PDF: This study was focused on the optimization of low-pressure ultrasonic spraying process for synthesis of pure gamma-Fe_2O_3 nanoparticles. As process variables, pressure in the reactor, precursor concentration, and reaction temperature were changed in order to control the chemical and microstructural properties of iron oxide nanoparticles including crystal phase, mean particle size and particle size distribution. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies revealed that pure gamma-Fe_2O_3 nanoparticles with narrow particle size distribution of 5-15 nm were successfully synthesized from iron pentacarbonyl (Fe(CO)_5) in hexane under 30 mbar with precursor concentrations of 0.1M and 0.2M, at temperatures over 800°C. Also magnetic properties, coercivity (H_c) and saturation magnetization (M_s) were reported in terms of the microstructure of particles based on the results from vibration sampling magnetometer (VSM).

[Korean]
Finite Element Analysis on the Effect of Die Corner Angle in Equal Channel Angular Pressing Process of Powders: Seung-Chae Yoon, Cheon-Hee Bok, Pham Quang, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2007;14(1):26-31.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.026

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Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve both real density and grain refinement of metallic powders. ECAP (Equal Channel Angular Pressing), one of the most promising processes in SPD, was used for the powder consolidation method. For understanding the ECAP process, investigating the powder density as well as internal stress, strain distribution is crucial. We investigated the consolidation and plastic deformation of the metallic powders during ECAP using the finite element simulations. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method. Effects of processing parameters on densification and density distributions were investigated.

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Finite element analysis of the bending behavior of a workpiece in equal channel angular pressing
Seung Chae Yoon, Anumalasetty Venkata Nagasekhar, Hyoung Seop Kim
Metals and Materials International.2009; 15(2): 215. CrossRef

[Korean]
Consolidation Behavior of Ti-6Al-4V Powder by Spark Plasma Sintering: J.H. Kim, J.K. Lee, T.S. Kim; J Korean Powder Metall Inst. 2007;14(1):32-37.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.032

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Abstract PDF: Using spark plasma sintering process (SPS), Ti-6Al-4V alloy powders were successfully consolidated without any contamination happened due to reaction between the alloy powders and graphite mold. Variation of microstructure and mechanical properties were investigated as a function of SPS temperature and time. Compared with hot isostatic pressing (HIP), the sintering time and temperature could be lowered to be 10 min. and 900°C, respectively. At the SPS condition, UTS and elongation were about 890 MPa and 24%, respectively. Considering the density of 98.5% and elongation of 24%, further improving the tensile strength would obtain by increasing the SPS pressure.

[Korean]
Fabrication of Cu-Zn Alloy Nano Powders by Wire Explosion of Electrodeposited Wires: Won-Baek Kim, Je-Shin Park, Chang-Yeul Suh, Jae-Chun Lee, Yong-Jun Oh, Jeong-Il Mun; J Korean Powder Metall Inst. 2007;14(1):38-43.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.038

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Abstract PDF: Cu-Zn alloy nano powders were fabricated by the electrical explosion of Zn-electroplated Cu wire along with commercial brass wire. The powders exploded from brass wire were composed mainly of alpha,beta,;and;gamma phases while those from electroplated wires contained additional Zn-rich phases as varepsilon, and Zn. In case of Zn-elec-troplated Cu wire, the mixing time of the two components during explosion might not be long enough to solidify as the phases of lower Zn content. This along with the high vapor pressure of Zn appears to be the reason for the observed shift of explosion products towards the high-Zn phases in electroplated wire system.

[Korean]
Fabrication of High-performance Carbon Counter Electrode for Dye-sensitized Solar Cells: Yeon-Ik Jang, Seung-Yong Lee, Dong-Hwan Kim, Jong-Ku Park; J Korean Powder Metall Inst. 2007;14(1):44-49.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.044

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Abstract PDF: In the fabrication of dye-sensitized solar cells (DSSCs), carbon counter electrode has been tested for replacing the platinum counter electrode which has two drawbacks: limited surface area and high material cost. Poor mechanical stability of carbon layer due to weak bonding strength to electrically conductive TCO (transparent conducting oxide) glass substrate is a crucial barrier for practical application of carbon counter electrode. In the present study a carbon counter electrode with high conversion efficiency, comparable to Pt counter electrode, could be fabricated by adaption of a bonding layer between particulate carbon material and TCO substrate.

[Korean]
Changes of Getter properties by Crystallization of Amorphous Zr-V-Ti alloy Powders: Je-Shin Park, Won-Baek Kim, Jin-Sun Baek; J Korean Powder Metall Inst. 2007;14(1):50-55.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.050

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Abstract PDF: The hydrogen sorption speeds of Zr_57V_36Ti_7 amorphous alloy and its crystallized alloys were evaluated at room temperature. Zr_57V_36Ti_7 amorphous alloy was prepared by ball milling. The hydrogen sorption rate of the partially crystallized alloy was higher than that of amorphous. The enhanced sorption rate of partially crystallized alloy was explained in terms of grain refinement that has been known to promote the diffusion into metallic bulk of the gases. The grain refinement could be obtained by crystallization of amorphous phase resulting in the observed increase in sorption property.

[Korean]
Metal Nano Powders as a New Getter Material: Won-Baek Kim, Je-Shin Park, Chang-Youl Suh, Han-Kwon Chang, Jae-Chun Lee, Mi-Young Park; J Korean Powder Metall Inst. 2007;14(1):56-62.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.056

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Abstract PDF: Getter property of nano-sized metallic powders was evaluated as a possible candidate for the future getter material. For the purpose, Ti powders of about 50 nm were prepared by electrical wire explosion. Commercial Ti powders of about 22 micrometer were tested as well for comparison. The room-temperature hydrogen-sorption speed of nano-sized Ti powders was 1.34;L/seccdotcm2 which was more than 4 times higher than that of micron-sized ones. The value is comparable to or even higher than those of commercial products. Its sorption speed increases with activation temperature up to 500°C above which it deteriorates due to low-temperature sintering effect of nano-sized particles.

[Korean]
Synthesis of Zirconium-Based Nanopowder by the Plasma Arc Discharge Process: Gil-Geun Lee, Kyong-Ju Kim, Je-Shin Park; J Korean Powder Metall Inst. 2007;14(1):63-69.; DOI: https://doi.org/10.4150/KPMI.2007.14.1.063

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Abstract PDF: The present study was focused on the synthesis of a zirconium-based alloyed nanopowder by the plasma arc discharge process. The chemical composition, phase structure, particle size and hydrogen sorption property of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD, SEM, XPS and the ASTM-F798 method. The chemical composition of the synthesized Zr-V-Fe-based powders approached that of the raw material with an increasing hydrogen fraction in the powder synthesis atmosphere. The synthesized Zr_55V_29Fe_16 powder consist of a mixed phase structure of the Zr,;ZrH_2,;FeV;and;Zr(V_1-xFe_x)_2 phases. This powder has an average particle size of about 20 nm. The synthesized Zr_55V_29Fe_16 nanopowder showed getter characteristics, even though it had a lower hydrogen sorption speed than the Zr_57;V36;Fe_7 getter powder. However, the synthesized Zr nanopowder with an average particle size of 20 nm showed higher hydrogen sorption speed than the Zr_57;V36;Fe_7 getter powder.

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