Journal of Powder Materials

Production and Application of Nanoparticles by the Chemical Vapor Condensation Process: Jin-Chun Kim, Gook-Hyun Ha, Chul-Jin Choi, Byoung-Kee Kim; J Korean Powder Metall Inst. 2005;12(4):239-248.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.239

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Synthesize of Nd₂Fe₁₄B Powders from 1-D Nd₂Fe₁₄B Wires using Electrospinning Process
Nu Si A Eom, Su Noh, Muhammad Aneeq Haq, Bum Sung Kim
Journal of Korean Powder Metallurgy Institute.2019; 26(6): 477. CrossRef

Fabrication and Characterization of Photocatalytic TiO₂ prepared by Polymer Complex Solution Method: Jeong-Wook Jang, Young-Keun Jeong, Tae-Oh Kim; J Korean Powder Metall Inst. 2005;12(4):249-254.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.249

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Titanium dioxide was prepared by Polymer Complex Solution Method(PCSM) according to the mole ratio of Titanium (IV) isopropoxide(TTIP)/solvent and polymer(Poly Ethylene Glycol). Polymer electrolytes were usually made by dispersing preproduced ceramic nanoparticles in a polymer matrix. Using this method, pure and nano-sized TiO_2 powder was synthesized through a simple procedure and polymer entrapment route. At the optimum amount of the polymer, the titanium ions are dispersed in solution and a homogeneous polymeric network is formed. The maximum intensity of anatase phase of TiO_2 was achieved by calcining at 500°C for 2h. The synthesized TiO_2 powders were nano-sized and the average size was about 50nm. Anatase/Rutile ratio of the synthesized TiO_2 was 70%/30%.

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Synthesis and characterization of N-doped TiO2/ZrO2 visible light photocatalysts
Ji Young Kim, Chan Soo Kim, Han Kwon Chang, Tae Oh Kim
Advanced Powder Technology.2011; 22(3): 443. CrossRef
Effects of ZrO2 addition on phase stability and photocatalytic activity of ZrO2/TiO2 nanoparticles
Ji-Young Kim, Chan-Soo Kim, Han-Kwon Chang, Tae-Oh Kim
Advanced Powder Technology.2010; 21(2): 141. CrossRef

Direct Solid State Synthesis of Zn₄Sb₃ by Hot Pressing and Thermoelectric Properties: Soon-Chul Ur; J Korean Powder Metall Inst. 2005;12(4):255-260.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.255

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Abstract PDF: Direct solid state synthesis by hot pressing has been applied in order to produce high efficiency Zn_4Sb_3 bulk specimens. Single phase Zn_4Sb_3 with 98.5% of theoretical density was successfully produced by direct hot pressing of elemental powders containing 1.2 at.% excess Zn. Thermoelectric properties as a function of temperature were investigated from room temperature to 600 K and compared with results of other studies. Transport properties at room temperature were also evaluated. Thermoelectric properties of single phase Zn_4Sb_3 materials produced by direct synthesis were measured and are comparable to the published data. Direct solid state synthesis by hot pressing provides a promising processing route in this material.

Effect of Debinding Conditions on the Microstructure of Sintered Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃: Jung-Yeul Yun, Jae-Ho Jeon, Suk-Joong L.Kang; J Korean Powder Metall Inst. 2005;12(4):261-265.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.261

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In order to fabricate complex-shaped polycrystalline ceramics by sintering, organic binders are usually pre-mixed with ceramic powders to enhance the formability during the shape forming process. These organic binders, however, must be eliminated before sintering so as to eliminate the possibilities of poor densification and unusual grain growth during sintering. The present work studies the effect of binder addition on grain growth behavior during sintering of 92(70Pb(Mg_1/3Nb_2/3)O_3-30PbTiO_3))-8PbO(mol%) piezoelectric ceramics. The microstructures of the sintered samples were examined for various heating profiles and debinding schedules of the binder removal process. Addition of Polyvinyl butyral(PVB) binder promoted abnormal grain growth especially in incompletely debinded regions. Residual carbon appears to change the grain shape from comer-rounded to faceted and enhance abnormal grain growth.

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Study on the Recovery Silver and Nanoparticles Synthesis from LTCC By-products of Lowly Concentrated Silver
Soyeong Joo, Nak-Kyoon Ahn, Chan Gi Lee, Jin-Ho Yoon
journal of Korean Powder Metallurgy Institute.2018; 25(3): 232. CrossRef

Photocatalytic Behaviors of Transition Metal Ions Doped TiO₂ Synthesized by Mechanical Alloying: S.H. Woo, W.W. Kim, S.J. Kim, C.K. Rhee; J Korean Powder Metall Inst. 2005;12(4):266-272.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.266

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Transition metal ions(Ni2+, Cr3+ and V5+) doped TiO_2 nanostructured powders were synthesized by mechanical alloying(MA) to shift the adsorption threshold into the visible light region. The synthesized powders were characterized by XRD, SEM, TEM and BET for structural analysis, UV-Vis and photoluminescence spectrum for the optical study. Also, photocatalytic abilities were evaluated by decomposition of 4-chlorophenol(4CP) under ultraviolet and visible light irradiations. Optical studies showed that the absorption wavelength of transition metal ions doped TiO_2 powders moved to visible light range, which was believed to be induced by the energy level change due to the doping. Among the prepared TiO_2 powders, NiO2+ doped TiO_2 powders, showed excellent photooxidative ability in 4CP decomposition.

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Influence of Cu modified surface states by sol gel Technique on Photocatalytic Activity of Titanium dioxide
Zulfiqar Ali, Atta ullah Shah, Zahid Ali, Arshad Mahmood
Materials Chemistry and Physics.2020; 249: 123169. CrossRef

Synthesis of TiN/TiB₂/Ti-silicides Nanocomposite Powders by Mechanochemical Reaction and its Reaction Mechanism: Young-Whan Cho, Ji-Woo Kim, Jae-Hyeok Shim, Jae-Pyoung Ahn, Kyu-Hwan Oh; J Korean Powder Metall Inst. 2005;12(4):273-278.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.273

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Abstract PDF: Nanostructured TiN/TiB_2/TiSi_2 and TiN/TiB_2/Ti_5Si_2 composite powders have been prepared by mechanochemical reaction from mixtures of Ti, BN, and Si_3N_4 powders. The raw materials have reacted to form a uniform mixture of TiN, TiB_2 and TiSi_2 or Ti_5Si_3 depending on the amount of Si_3N_4 used in the starting mixtures, and the reaction proceeded through so-called mechanically activated self-sustaining reaction (MSR). Fine TiN and TiB_2 crystallites less than a few tens of nanometer were homogeneously dispersed in the amorphous TiSi_2 or Ti_5Si_3 matrix after milling for 12 hours. These amorphous matrices became crystalline phases after annealing at high temperatures as expected, but the original microstructure did not change significantly.

Application of Mechanical Alloying Method on the Fabrication of Zinc Sulfide Photo-luminescence Powders: In-Shup Ahn, Woo-Hyun Chong, Sung-Yeal Bae, Tek-Kyoung Sung, Dong-Kyu Park; J Korean Powder Metall Inst. 2005;12(4):279-283.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.279

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Abstract PDF: In this study, the ZnS composite powders for host material in phosphor was synthesized in situ by mechanical alloying. As the mechanical alloying time increases, particle size of ZnS decreases. ZnS powders of 1.85;mum in a mean size was fabricated by mechanical alloying for 10h. The crystal structures of ZnS powders were investigated by X-ray diffraction and the photo-luminescence properties was evaluated with the optical spectra analyzer. The steady state condition of mechanically alloyed ZnS was obtained as a mean particle size of 2;mum in 5h milling. The sphalerite and wurtize structures coexist in the ZnS mechanically alloyed for 5h. The ZnS powder mechanically alloyed for 10h grows to the sphalerite structure. And the strong emission peaks of ZnS are observed at 480 nm wave length at the powders of mechanically alloyed for 10h, but the sphalerite and wurtize structures in ZnS coexist and emission peaks are not appeared at the powders of mechanically alloyed for 10h.

Shapes of ZnO Nanostructures Grown in the Aqueous Solutions: Yeon-Ik Jang, Hoon Park, Seung-Yong Lee, Jae-Pyoung Ahn, Jong-Ku Park; J Korean Powder Metall Inst. 2005;12(4):284-290.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.284

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Abstract PDF: ZnO nanostructures with various shapes were synthesized under ambient pressure condition by a wet chemical reaction method. Nanorods of ZnO with hexagonal cross-section and their aggregates with radiate shape were synthesized. Precursor concentration affected considerably the shape evolution of ZnO nanorods. Low precursor concentration was proved to be more preferable to the growth of ZnO nanorods, which is attributed to the intrinsic characteristics of chemical reaction in the synthesis of ZnO from zinc compounds.

Formation of CdSe Hollow Sphere by In-Situ-Template-Interface Reaction (ISTIR) Method: Moon-Hee Choi, Yoon-Bok Lee, Hyong-Kuk Kim, Young-Mok Rhyim, Jin-Chun Kim, Young-Seok Kim, Yang-Do Kim; J Korean Powder Metall Inst. 2005;12(4):291-295.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.291

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Abstract PDF: CdSe hollow sphere with average size of about 30-50 nm was synthesized from the mixed solution of cadmium chloride (CdCl_2), sodium selenosulfate (Na_2SeSO_3) and ethylenediamine(EDA, H_2NCH_2CH_2NH_2) at room temperature. The molar ratio of EDA to Cd2+ showed the most significant effect on the morphology of CdSe hollow sphere. This paper will present and discuss the possible formation mechanism of CdSe hollow sphere based on the observation of morphological changes.

Fabrication and Properties of High Strength Hypereutectic Al-Si Powder by Gas Atomization Process I. Powder Production and Compressibility: Yong-Jin Kim, Jin-Chun Kim; J Korean Powder Metall Inst. 2005;12(4):296-302.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.296

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Abstract PDF: In order to improve mechanical properties, the hypereutectic Al-20 wt%Si based prealloy powder was prepared by gas atomization process. Microstructure and compressibility of the atomized Al-Si powder were investigated. The average powder size was decreased with increasing the atomization gas pressure. Size of primary Si particles of the as-atomized powder was about 5-8;mum. The as-atomized Al-Si powder such as AMB 2712 and AMB 7775 to increase compressibility and sinterability. Relative density of the mixed powder samples sintered at 600°C was reached about 96% of a theoretical density.

Phase Change of Precipitates and Age Hardening in Rapidly Solidified Mg-Zn-Ca Base Alloys: Won-Wook Park, Bong-Sun You; J Korean Powder Metall Inst. 2005;12(4):303-308.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.303

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Abstract PDF: Various kinds of Mg-Zn-Ca base alloys were rapidly quenched via melt spinning process. The meltspun ternary and quaternary alloy ribbons were heat-treated, and then the effects of additional elements on age hardening behavior and phase change of precipitates were investigated using Vickers hardness tester, XRD, and TEM equipped with EDS system. In ternary alloys, age hardening was mostly due to the distribution of Mg_6Ca_2Zn_3 and Mg_2Ca. The stable phases of precipitates were varied according to the aging temperature and the alloy composition. With the increase of Ca content, Mg_2Ca precipitates were detected more than Mg_6Ca_2Zn_3 precipitates. In quaternary alloys, the precipitates taken from Mg-Zn-Ca-Co were identified as new quaternary phase, whereas those taken from Mg-Zn-Ca-Zr as MgZnCa containing Zr. In general, the ternary alloy showed higher peak hardness and thermal stability than the quaternary considering the total amounts of the solutes. It implies that the structure of precipitate should be controlled to have the coherent interface with the Mg matrix.

자성 나노입자를 이용한 온열치료 기술: J.H. Yu, D.W. Lee, Y.J. Kim, Y.H. Choa; J Korean Powder Metall Inst. 2005;12(4):309-314.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.309

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