Journal of Powder Materials

Fabrication and Application of Aluminum Powders: J Korean Powder Metall Inst. 2002;9(5):287-302.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.287

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Fabrication and Mechanical Properties of Powder Metallurgical High Speed Steels with Various Co Contents: J Korean Powder Metall Inst. 2002;9(5):303-306.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.303

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Abstract PDF: P/M high speed steels with various Co contents were fabricated by gas atomization and Canning/HIP process. As Co content in P/M high speed steel increased, hardness, transverse rupture strength and yield strength in compressive testing increased due to solid solution hardening of Co in matrix. Especially, PM high speed steels with Co have high deformation resistance to repeated compressive loading.

High Temperature Compressive Properties of Tungsten Activated Sintered Pare Prepared by 0.4 wt.% Ni-doped Tungsten Powder Compacts: J Korean Powder Metall Inst. 2002;9(5):307-314.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.307

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Abstract PDF: The high temperature deformation behavior of the activated sintered W powder compacts was investigated. The W compact showed the relative density of 94% with the average W grain size of 23mutextrmm by activated sintering at 1400°C for 1 hour. Compression tests were carried out in the temperature range of 900-1100°C at the strain rate range of 100/sec - 10-3/sec. True stress-strain curve and microstructure exhibited the grain boundary brittleness which was dependent on the compression test temperature. The activated sintered W compact showed that the maximum stress as well as the strain at the maximum stress was abruptly decreased as the test temperature increase from 900°C to 1000 and 1100°C regardless of the strain rate. The discrepancy of the microstructure in the specimen center was obviously observed with the increase of the test temperature. After compression test at 900°C the W grain was severely deformed normally against the compression axis. However, after compression test at 1000°C and 1100°C the W grain was not deformed, but the microcrack was formed in the W grain boundary. The Ni-rich second phase segregated along the W grain boundary could be partly unstable over 900°C and affect the poor mechanical property of the activated sintered W compact.

Characteristic of Tantalum Powder and Effect of Reaction Temperature on the amount of Diluent: J Korean Powder Metall Inst. 2002;9(5):315-321.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.315

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Pure tantalum powder has been produced by combining Na as a reducing agent, K_2TaF_7 as feed material, KCl and KF as a diluent in a stainless steel(SUS) bomb, using the method of metallothermic reduction. The present study investigated the effect of the amount of the diluent and reaction temperature on the characteristics of tantalum powder in the production process. The temperature applied in this study 850°C and the amount of the additional reductant from +5% of the theoretical amount used for the reduction of the entire K_2TaF_7. The results showed that as the amount of the diluent increased, the reaction temperature became lower because the diluent prevented a temperature rise. Also, according to the mixture ratio of the feed materials and the diluent changed from 1 : 0.25 to 1 : 2, the particle size decreased from 5mutextrmm to 1mutextrmm and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. The average size of Tantalum powder, 2-4mutextrmm, was close to that of the commercial powders(2-5mutextrmm). Also under this condition, impurities contained in the powder were within the range allowed for the commercial Ta powders.

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Characteristics and production of tantalum powders for solid-electrolyte capacitors
Jae Sik Yoon, Byung Il Kim
Journal of Power Sources.2007; 164(2): 959. CrossRef
Production of Tantalum Powder by External Continuous Supply of Feed Materials and Reductant
Jae Sik Yoon, Hyeoung Ho Park, In Sung Bae, Shoji Goto, Byung Il Kim
MATERIALS TRANSACTIONS.2005; 46(2): 272. CrossRef
Production of Tantalum Powder by External Continuous Supply of Feed Material and Reductant
Jae Sik Yoon, Hyeoung Ho Park, In Sung Bae, Shoji Goto, Byung Il Kim
Journal of the Japan Institute of Metals.2004; 68(4): 247. CrossRef

Characterization of Fe-Co Nanocomposite Powders Produced by Chemical Vapor Condensation Methods: H. Z., D. Z.; J Korean Powder Metall Inst. 2002;9(5):322-328.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.322

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Fe-Co nanocomposite powders with different composition were prepared by chemical vapor condensation (CVC) process and their characterizations were studied by means of X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The particles having the mean size of 5~25 nm consisted of metallic cores and oxide shells. The Co contents and particle size increased with increasing the carrier gas flow rate of Co precursor. The saturation magnetization and coercivity increased with increasing Co content. and the saturation magnetization maximized at the 40 wt.%Co. The Fe-Co nanocomposite powder oxidized at 400°C showed the maximum coercivity of 1739 Oe.

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Fabrication and Characterization of Nano-sized Fe-50 wt% Co Powder from Fe- and Co-nitrate
도형 류, 승탁 오
Korean Journal of Materials Research.2010; 20(10): 508~512. CrossRef
Characterization of Ni Nanopowders Produced by Electrical Explosion of Wire Technique
Hwan Tae Kim, Won Sik Seo, Dae Hwan Kwon, Pyuck Pa Choi, Ji Soon Kim, Young Soon Kwon
Materials Science Forum.2006; 510-511: 710. CrossRef
Effect of Chamber Pressure on the Microstructure of Fe Nano Powders Synthesized by Plasma Arc Discharge Process

Journal of Korean Powder Metallurgy Institute.2004; 11(4): 328. CrossRef

Microstructure of W-Cu Composite Powders with Variation of Milling Method during Mechanochemical Process: J Korean Powder Metall Inst. 2002;9(5):329-335.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.329

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Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using WO_3-CuO mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in H_2 atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

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Grinding Behaviour of Aluminum Powder for Al/CNTs Nano Composites Fabrication by Dry Grinding Process Using a High Speed Planetary Ball Mill
Heekyu Choi, Jehyun Lee, Seongsoo Kim, Gyungpil Choi, Daehyung Bae, Sungbak Lee, Woong Lee
Korean Journal of Materials Research.2013; 23(2): 89. CrossRef

Fabrication of Zirconium Phosphate Nanoparticles through Solution Technique: J Korean Powder Metall Inst. 2002;9(5):336-340.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.336

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Abstract PDF: The alpha-zirconium phosphate particles as fine as 20 nm were fabricated through solution technique using ZrOCl_2cdot8H_2O and H_3PO_4 as precursors. Stability of alpha-Zirconium phosphate could be ensured by adding excess phosphoric acid to a stoichiometric composition Instead of using reflux route that resulted in coarsening of particles due to an inevitably long aging. The excess phosphorous incorporated in the crystal could be successfully eliminated afterwards through careful washing. Moreover, heavily agglomerated particles are observed before washing, but fairly dispersed state is found out after washing treatment. Thus, it is found that dispersed state as well as phase stability is ensured through proper washing treatment.

Study of Magnetic Fe₂O₃ Nano-particles Synthesized by Pulsed Wire Evaporation (PWE) Method: J Korean Powder Metall Inst. 2002;9(5):341-345.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.341

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Abstract PDF: Nanoparticles of Fe_2O_3 with a mean particle size of 4-30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mossbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mossbauer spectrum, the amounts of gamma-Fe_2O_3 and alpha-Fe_2O_3 in as-prepared sample are about 70% and 30%, respectively. The coercivity (53 Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk gamma-Fe_2O_3. The low value of coercivity and saturation magnetization indicate that the gamma-Fe_2O_3 phase nearly shows the spin glass-like behavior. Analysis of the set of Mossbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk gamma-Fe_2O_3 and alpha-Fe_2O_3. A quadrupole line on the center of spectrum represents of superparamagnetic phase of gamma-Fe_2O_3 with a mean particle size of 7 nm or below.

Synthesis of Two-Component Titanate Powders Using Ethylene Glycol Solution: J Korean Powder Metall Inst. 2002;9(5):346-351.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.346

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Abstract PDF: Pure and fine, two-component titanate powders (barium titanate, calcium titanate etc.) were synthesized by an ethylene glycol method. Titanium isopropoxide and other metal ionic salts were dissolved in liquid-type ethylene glycol without any precipitation. In non-aqueous system, the amount of ethylene glycol affected the solubility and homogeneity of metal cation sources in the solution. At the optimum amount of the polymer, the metal ions were dispersed effectively in solution and a homogeneous polymeric network was formed. Most of the synthesized powders had sub-micron or nano-size primary particles after calcination and the agglomerated calcined powders were easily ground by ball milling process. All synthesized titanate powders had stable crystallization behavior at low temperature and high specific surface area after ball milling. The crystallization behavior and the microstructures of the calcined powders were affected on the ethylene glycol content.

Effect of Addition of Other Componene (B₄C, Mn, TiB₂, B) on TiC-Ni₃Al Cermet: J Korean Powder Metall Inst. 2002;9(5):352-358.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.352

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Abstract PDF: The effects of boron or manganese added as B_4C, Mn, TiB_2, B on TiC-30vo1.%Ni_3Al cermet sintered at 1380 and 1400°C for 1 hour, were examined in relation with shrinkage, relative density, microstructure, lattice parameter, hardness and fracture toughness (K_IC). The results are summarized as follows: 1) The highest shrink-age showed about 30.5% in the specimen added B_4C and the maximum relative density was about 99% in the specimen added TiB_2; 2) The grains of TiC were grown during sintering and made the surrounding structure by adding boron and manganese. The largest grain size showed about 2.8mutextrmm in the specimen with boron sintered at 1400°C;3) The lattice parameter of TiC was about 4.325AA and Ni_3Al about 3.592AA by adding other elements; 4) The highest hardness was about 1100kgf/textrmmm2 in the specimen with B4C; 5) The fracture toughness (K_IC) showed about 15MNm-3/2 in the specimen added TiB_2.

Formation and Chemical Leaching of a Non-Equilibrium Al(Fe-Cu) Alloy Powder produced by Rod-Milling: J Korean Powder Metall Inst. 2002;9(5):359-364.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.359

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Abstract PDF: We report the structure, thermal and magnetic properties of a non-equilibrium Al_0.6(Fe_50Cu_50)_0.4 alloy powder produced by rod milling and chemical leaching. An X-ray diffractometry(XRD), a transmission electron microscope(TEM), a differential scanning calorimeter(DSC), a vibrating sample magnetometer(VSM), and superconducting quantum interference device(SQUID) were utilized to characterize the as-milled and leaching specimens. The crystallite size reached a value of about 8.82 nm. In the DSC experiment, the peak temperatures and crystallization temperatures decreased with increasing milling time. The activation energy of crystallization is 200.5 kJ/mole for as-milled alloy powder. The intensities of the XRD peaks of as-milled powders associated with the bcc type Al_0.5Fe_0.5 structure formative at 350°C sharply increase with increasing annealing temperature. Above 400°C, peaks alloted to Al_0.5Fe_0.5 and Al_5Fe_2 are observed. After annealing at 600°C for 1h, the leached Ll specimen transformed into bcc alpha-Fe and fcc Cu phases, accompanied by a change in the structural and magnetic properties. The saturation magnetization decreased with increasing milling time, and a value of about 8.42 emu/g was reached at 500 h of milling. The coercivity reached a maximum value of about 142.7 Oe after 500 h of milling. The magnetization of leached specimens as function of fields were higher at 5 K, and increased more sharply at 5 K than at 100 K.

Study on the Synthesis and thermal Characteristics of Nano Porous Silica Powder: J Korean Powder Metall Inst. 2002;9(5):365-369.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.365

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Abstract PDF: Silica hydrogel was synthesized by the reaction of liquid sodium silicate with sulfuric acid. The condensation polymerization of the synthesized hydrogel was carried out via an aging process under the acidic or alkaline conditions. Nano porous silica with the pore size below 3 nm and surface area of 715m2/g, was obtained by the above processes in acidic ranges(pH : 3~5). The pore size and surface area of the silica varied with pH, and in alkaline ranges(pH : 8~10), those were 21 nm and 300m2/g respectively. The characteristics of the silica varied with the thermal treatment which caused the change of surface area, pore volume and pore diameter.

나노결정립분말을 이용한 리튬 2차전지용의 새로운 전지재료: J Korean Powder Metall Inst. 2002;9(5):370-375.; DOI: https://doi.org/10.4150/KPMI.2002.9.5.370

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Syntheses of nano-sized Co-based powders by carbothermal reduction for anode materials of lithium ion batteries
Seong-Hyeon Hong, Myoung Youp Song
Ceramics International.2018; 44(4): 4225. CrossRef
Electrochemical properties of nano-cobalt powder prepared by chemical reduction with and without cetyltrimethylammonium bromide and carbon-coated at 500 °C for secondary lithium Batteries
Seong-Hyeon Hong, Yeong-Mi Jin, Myoung Youp Song
Metals and Materials International.2014; 20(4): 793. CrossRef
Synthesis of Nanocobalt Powders for an Anode Material of Lithium-Ion Batteries by Chemical Reduction and Carbon Coating
Seong-Hyeon Hong, Yeong-Mi Jin, Kyung Tae Kim, Cheol-Woo Ahn, Dong-Su Park, Myoung Youp Song
Journal of Nanomaterials.2014; 2014: 1. CrossRef

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