Journal of Powder Materials

Volume 15(1); February 2008

[Korean]
Fabrication of ZnS-SiO₂ Composite and its Mechanical Properties: Dae-Hoon Shin, Gil-Su Kim, Young-Jung Lee, Hoon Cho, Young-Do Kim; J Korean Powder Metall Inst. 2008;15(1):1-5.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.001

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Abstract PDF: ZnS-SiO_2 composite is normally used for sputtering target. In recent years, high sputtering power for higher deposition rate often causes crack formation of the target. Therefore the target material is required that the sintered target material should have high crack resistance, excellent strength and a homogeneous microstructure with high sintered density. In this study, raw ZnS and ZnS-SiO_2 powders prepared by a 3-D mixer or high energy ball-milling were successfully densified by spark plasma sintering, the effective densification method of hard-to-sinter materials in a short time. After sintering, the fracture toughness was measured by the indentation fracture (IF) method. Due to the effect of crack deflection by the residual stress occurred by the second phase of fine SiO_2, the hardness and fracture toughness reached to 3.031 GPa and 1.014MPacdotm1/2, respectively.

[Korean]
Synthesis of Yba₂Cu₃O_7-y Superconductor using a Low Purity BaCO₃ Powder: Chan-Joong Kim, Soon-Dong Park, Jung-Suk Choi, Byung-Hyuk Jun, Jong-Baik Moon, Sang-Heon Lee, Tae-Hyun Sung; J Korean Powder Metall Inst. 2008;15(1):6-12.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.006

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Abstract PDF: [ YBa_2Cu_3O_7-y ](123) powders were synthesized by the solid state reaction method using two different purity BaCO_3 powders (99.75% and 99.7% purity) and Y_2O_3 (99.9%) and CuO (99.9%) powders. The effect of BaCO_3 purity on the formation of a 123 phase and the superconducting properties were investigated. The mixtures of raw powders were calcined at temperature ranges of 800°C-880°C in air and finally made into a single grain samples by a melt processing with top seeding. It was found that a 123 phase was well formed at temperature above 870°C, but the purity effect on the 123 formation was negligible. The single-grain 123 samples prepared from the different BaCO_3 powders showed the same T_c value of 90.5 K and similar J_c values about 104;A/cm2 at 0 T and 77 K, and 103;A/cm2 at 2 T and 77 K. This result indicates that the low purity, cheap price BaCO_3 powder can be used as a raw material for the fabrication of single-grain, high-J_c superconducting levitator.

[Korean]
Preparation of Visible-light Responsive TiO₂:Zr, N Photocatalysts by Polymer Complex Solution Method and Photo-degradation of NO: Jae-Young Choi, Ji-Young Kim, Young-Hyuek Cho, Hee-Dong Jang, Han-Kwon Chang, Byoung-Gon Kim, Tae-Oh Kim; J Korean Powder Metall Inst. 2008;15(1):13-17.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.013

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Abstract PDF: Visible-light responsive TiO_2:Zr, N powders were prepared by polymer complex solution method and the particle properties were characterized by using transmission electron microscope, BET method, X-ray diffractometer and UV-Vis spectrophotometer. The photocatalytic reactivity of the catalysts was also estimated by analyzing NO degradation. Polyhedral TiO_2 powder having about 20 um in the average particle diameter was successfully prepared, The XRD analysis revealed that the as-prepared powder consisted of anatase and rutile phases. The light absorption of the as-prepared TiO_2:Zr, N powder was shifted to the visible light. In addition, the as-prepared TiO_2:Zr, N nanoparticles showed the higher photocatalytic activity than the commercial TiO_2 under both UV and visible lights.

[Korean]
Effect of Annealing Temperature on the Electromagnetic Wave Absorbing Properties of Nanocrystalline Soft-magnetic Alloy Powder: S.H. Hong, K.Y. Sohn, W.W. Park, B.G. Moon, Y.S. Song; J Korean Powder Metall Inst. 2008;15(1):18-22.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.018

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Abstract PDF: The electromagnetic (EM) wave absorption properties with a variation of crystallization annealing temperature have been investigated in a sheet-type absorber using the Fe_73Si_16B_7Nb_3Cu_1 alloy powder. With increasing the annealing temperature the complex permeability (µ_r), permittivity (varepsilon_r) and power absorption changed. The EM wave absorber shows the maximum permeability and permittivity after the annealing at 610°C for 1 hour, and its calculated power absorption is above 80% of input power in the frequency range over 1.5 GHz.

[Korean]
Variation of Tensile Strength by Addition of Y₂O₃ and Effect of Aging Treatment in Ni Base Alloy Fabricated by MA Method: Il-Ho Kim, Won-Sik Lee, Se-Hyun Ko, Jin-Man Jang, Sook-In Kwun; J Korean Powder Metall Inst. 2008;15(1):23-30.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.023

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Abstract PDF: Ni-20Cr-20Fe-5Nb alloy with or without Y_2O_3 was manufactured by mechanical alloying process and consolidated by spark plasma sintering (SPS). The grain size of the alloy with Y_2O_3 was smaller than that of alloy without Y_2O_3 which results from the effect of Y_2O_3 suppressing grain growth. The tensile strength at room temperature was increased by the addition of Y_2O_3 but decreased abruptly at temperature above 600°C. It seems to result from the change of deformation mechanism due to fine grain size, that is, grain boundary sliding is predominant at above 600°C while internal dislocation movement is predominant at below 600°C. After conventional heat treatment process of solution treatment and aging, a small amount of delta(Ni_3Nb) phase was formed in Ni-20Cr-20Fe-5Nb alloy while a large amount of gamma"(Ni_3Nb) was formed in Inconel 718 in the previous report. This is due to exhaustion of Nb content by the formation of NbC during consolidation.

[Korean]
Consolidation and Mechanical Property of Rapidly Solidified Al-20 wt% Si Alloy Powders by Continuous Equal Channel Multi-Angular Pressing: Seung-Chae Yoon, Cheon-Hee Bok, Min-Hong Seo, Soon-Jik Hong, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2008;15(1):31-36.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.031

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3 Citations

Abstract PDF

In this study, the bottom-up powder metallurgy and the top-down severe plastic deformation (SPD) techniques for manufacturing bulk nanomaterials were combined in order to achieve both full density and grain refinement without grain growth of rapidly solidified Al-20 wt% Si alloy powders during consolidation processing. Continuous equal channel multi-angular processing (C-ECMAP) was proposed to improve low productivity of conventional ECAP, one of the most promising method in SPD. As a powder consolidation method, C-ECMAP was employed. A wide range of experimental studies were carried out for characterizing mechanical properties and microstructures of the ECMAP processed materials. It was found that effective properties of high strength and full density maintaining nanoscale microstructure are achieved. The proposed SPD processing of powder materials can be a good method to achieve fully density and nanostructured materials.

Citations

Citations to this article as recorded by

X-ray diffraction study on the microstructure of a Mg–Zn–Y alloy consolidated by high-pressure torsion
Péter Jenei, Jenő Gubicza, Eun Yoo Yoon, Hyoung Seop Kim
Journal of Alloys and Compounds.2012; 539: 32. CrossRef
Microstructures and mechanical properties of Mg–Zn–Y alloy consolidated from gas-atomized powders using high-pressure torsion
Eun Yoo Yoon, Dong Jun Lee, Taek-Soo Kim, Hong Jun Chae, P. Jenei, Jeno Gubicza, Tamas Ungár, Milos Janecek, Jitka Vratna, Sunghak Lee, Hyoung Seop Kim
Journal of Materials Science.2012; 47(20): 7117. CrossRef
Synthesis and microstructure control of Mg alloy powder composites by multi-extrusion
Taek-Soo Kim, Hong Jun Chae, Sun-Mi Kim, Hanshin Choi, Hye Sung Kim
Journal of Alloys and Compounds.2011; 509: S247. CrossRef

[Korean]
Densification of Al₂O₃ Nanopowder by Magnetic Pulsed Compaction and Their Properties: R.C. Kang, M.K. Lee, W.W. Kim, C.K. Rhee, S.J. Hong; J Korean Powder Metall Inst. 2008;15(1):37-45.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.037

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2 Citations

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This article presents the challenges toward the successful consolidation of Al_2O_3 nanopowder using magnetic pulsed compaction (MPC). In this research the ultrafine-structured Al_2O_3 bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were investigated. The obtained density of Al_2O_3 bulk prepared by the combined processes was increased with increasing MPC pressure from 0.5 to 1.25 GPa. Relatively higher hardness and fracture toughness in the MPCed specimen at 1.25 GPa were attributed to the retention of the nanostructure in the consolidated bulk without cracks. The higher fracture toughness could be attributed to the crack deflection by homogeneous distribution and the retention of nanostructure, regardless of the presence of porosities. In addition, the as consolidated Al_2O_3 bulk using magnetic pulsed compaction showed enhanced breakdown voltage.

Citations

Citations to this article as recorded by

Microstructure and Characteristics of Ag-SnO2Contact Materials Prepared by Magnetic Pulsed Compaction
J.S. Park, Y.J. Kim, M.H. Lee, H.S. Lee, S.J. Hong, J.K. Lee
Journal of Korean Powder Metallurgy Institute.2011; 18(4): 372. CrossRef
The Effect of Ti Powder addition on Compaction Behavior of TiO2Nano Powder
Jin-Sub Park, Hyo-Seob Kim, Ki-Seok Lee, Jeong-Goo Lee, Chang-Kyu Rhee, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2009; 16(3): 223. CrossRef

[English]
Laser Microfabrication for Silicon Restrictor: Kwang-Ryul Kim, Young-Keun Jeong; J Korean Powder Metall Inst. 2008;15(1):46-52.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.046

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Abstract PDF: The restrictor, which is a fluid channel from a reservoir to a chamber inside a thermal micro actuator, has been fabricated using ArF and KrF excimer lasers, Diode-Pumped Solid State Lasers (DPSSL) and femtosecond lasers for a feasibility study. A numerical model of fluid dynamics for the actuator chamber and restrictor is presented. The model includes bubble formation and growth, droplet ejection through nozzle, and dynamics of fluid refill through the restrictor from a reservoir. Since an optimized and well-fabricated restrictor is important for a high frequency actuator, some special beam delivery setups and post processing techniques have been researched and developed. The effects of variations of the restrictor length, diameter, and tapered shapes are simulated and the results are analyzed to determine the optimal design. The numerical results of droplet velocity and volume are compared with the experimental results of a cylindrical-shaped actuator. It is found that the micro actuators having tapered restrictors show better high frequency characteristics than those having a cylindrical shape without any notable decrease of droplet volume. The laser-fabricated restrictors demonstrate initial feasibility for the laser direct ablation technique although more development is required.

[Korean]
The Characteristic Changes of Electromagnetic Wave Absorption in Fe-based Nanocrystalline P/M Sheet by the Additions of BaTiO₃ Powder and Dispersant: Mi-Rae Kim, Hyeon-Jeong Cho, Won-Wook Park; J Korean Powder Metall Inst. 2008;15(1):53-57.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.053

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2 Citations

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The amorphous Fe_73Si_16B_7Nb_3Cu_1(at%) alloy strip was pulverized using a jet mill and an attrition mill to get flake-shaped powder. The flake powder was mixed with dielectric BaTiO_3 powder and its dispersant to increase the permittivity. The powders covered with dielectric powders and its dispersant were mixed with a binder and a solvent and then tape-cast to form sheets. The absorbing properties of the sheets were measured to investigate the roles of the dielectric powder and its dispersant. The results showed that the addition of BaTiO_3 powders and its dispersant improved the absorbing properties of the sheets noticeably. The powder sheet mixed with 5 wt% of BaTiO_3 powder and 1 wt% of dispersant showed the best electromagnetic wave absorption rate because of the increase of the permittivity and the electrical resistance.

Citations

Citations to this article as recorded by

Effects of various barium titanate additives on the electromagnetic wave absorbing behavior of FeSiBNbCu P/M sheets
S J Woo, S I Kim, M R Kim, K Y Sohn, Y S Song, W W Park
Journal of Physics: Conference Series.2009; 144: 012061. CrossRef
The Effect of Carbon Black Additions on Electromagnetic Wave Absorption of Fe73Si16B7Nb3Cu1 Base P/M Sheets
Sun-I Kim, K. Y. Sohn, W. W. Park
MRS Proceedings.2008;[Epub] CrossRef

[Korean]
Joining of Reaction Bonded SiC using Preceramic Polymer: Dong-Hwa Lee, Deug-Jooug Kim; J Korean Powder Metall Inst. 2008;15(1):58-62.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.058

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1 Citations

Abstract PDF

Reaction bonded silicon carbide (RBSiC) is an important engineering ceramic because of its high strength and stability at elevated temperatures, and it is currently fabricated using reasonably cheap manufacturing processes, some of which have been used since the 1960s. However, forming complicated shapes from these materials is difficult because of their poor workability. The purpose of this work is to join the reaction-bonded SiC parts using a preceramic polymer as joint material. The manufacturing of ceramic material in the system Si-O-C from preceramic silicon containing polymers such as polysiloxanes has attained particular interest. The mixtures of preceramic polymer and filler materials, such as SiC, Si and MoSi, were used as a paste for the joining of reaction sintered SiC parts. The joining process during the annealing in Ar atmosphere at 1450°C were described. The maximum strength of the joints was 63 MPa for the specimen joined with 10 vol.% of MoSi_2 and 30 vol.% of SiC as filler materials. Fracture occurred in the joining layer. This indicates that the joining strength is limited by the strength of the joint materials.

Citations

Citations to this article as recorded by

Joining of SiCf/SiC using polycarbosilane and polysilazane preceramic mixtures
Dong-Hyuk Jeong, Arifin Septiadi, Pipit Fitriani, Dang-Hyok Yoon
Ceramics International.2018; 44(9): 10443. CrossRef

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