Journal of Powder Materials

Trend of Advanced Technology for the Synthesis of Nanopowders in Russia by Chemical Process: Dong-Soo Kim, Dong-Won Lee, Byoung-Kee Kim; J Korean Powder Metall Inst. 2006;13(4):233-242.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.233

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Synthesis and Phase Transformation Behavior of YAG Powders by a Mechanochemical Solid Reaction: Hyun-Gi Jung, Gil-Ho Hwang, Kwang-Young Lim, Young-Hun Lee, Sung-Goon Kang; J Korean Powder Metall Inst. 2006;13(4):243-249.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.243

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Yttrium aluminum garnet (YAG) powders were synthesized via mechanochemical solid reaction using Y_2O_3 with three types of aluminum compounds. Y_2O_3 reacted mechanochemically with all A1 compounds and formed YAM (yttrium aluminum monoclinic), YAG and YAP (yttrium aluminum perovskite) phases depending on the starting materials. The ground samples containing gamma-A1_2O_3 showed the best reactivity, whereas the ground sample containing A100H, which had the largest surface area, exhibited pure YAG after calcination at 1200°C. The sample containing Al had the least reactivity, producing YAP along with YAG at 1200°C. The types and grinding characteristics of the starting materials and grinding time are believed to be important factors in the mechanochemical synthesis of YAG.

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Optical Properties of Spherical YAG:Ce³⁺ Phosphor Powders Synthesized by Atmospheric Plasma Spraying Method Appling PVA Solution Route and Domestic Aluminium Oxide Seed
Yong-Hyeon Kim, Sang-Jin Lee
journal of Korean Powder Metallurgy Institute.2023; 30(5): 424. CrossRef
Pulverization and Densification Behavior of YAG Powder Synthesized by PVA Polymer Solution Method
Hyun-Ho Im, Sang-Jin Lee
Korean Journal of Materials Research.2020; 30(11): 573. CrossRef
Synthesis of YAG:Ce3+ phosphor powders employing several types of alumina seeds
A-Reum Kim, Yong-Hyeon Kim, Sang-Jin Lee
Metals and Materials International.2015; 21(2): 324. CrossRef
Effect of PVA Polymerization on Synthesis of YAG:Ce3+Phosphor Powders Prepared by a Solid-liquid Hybrid Route
A-Reum Kim, Sang-Jin Lee
Journal of the Korean Ceramic Society.2014; 51(5): 424. CrossRef
Synthesis of YAG:Ce3+Phosphor Powders by Polymer Solution Route and Alumina Seed Application
Yong-Hyeon Kim, Sang-Jin Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(1): 37. CrossRef

Wear Behaviors of Gas Atomized and Extruded Hypereutectic Al-Si Alloys: Hyeong-Ho Jin, Ki-Young Nam, Yong-Jin Kim, Yong-Ho Park, Seog-Young Yoon; J Korean Powder Metall Inst. 2006;13(4):250-255.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.250

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Abstract PDF: Wear behaviors of gas atomized and extruded Al-Si alloys were investigated using the dry sliding wear apparatus. The wear tests were conducted on Al-Si alloy discs against cast iron pins and vice versa at constant load of 10N with different sliding speed of 0.1, 0.3, 0.5m/s. In the case of Al-Si alloy discs slid against the cast iron pins, the wear rate slightly increased with increasing the sliding speed due to the abrasive wear occurred between Al-Si alloy discs and cast iron pins. Conversely, in the case of cast iron discs against Al-Si alloy pins, the wear rate decreased with increasing the sliding speed up to 0.3m/s. However, the wear rate increased with increasing the sliding speed from 0.3m/s to 0.5m/s. It could be due to adhesive wear behavior and abrasive wear behavior_between cast iron discs and Al-Si alloy pins.

Effect of Grain Size Control and Binder Additions on the Soft Magnetic Properties of Fe-based Nanocrystalline Powder Cores: E.K. Cho, H.J. Cho, H.T. Kwon, E.M. Cho, H.H. Ryu, K.Y. Sohn, W.W. Park; J Korean Powder Metall Inst. 2006;13(4):256-262.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.256

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Abstract PDF: The amorphous Fe_73Si_16B_7Nb_3Cu_1 alloy strip was pulverized to get a flake-shaped powder after annealing at 425°C for 90 min and subsequently ground to obtain finer flake-shaped powder by using a ball mill. The powder was mixed with polyimide-based binder of 0.5sim3wt%, and then the mixture was cold compacted to make a toroidal powder core. After crystallization treatment for 1 hour at 380sim600°C, the powder was transformed from amorphous to nanocrystalline with the grain size of 10sim15nm. Soft magnetic characteristics of the powder core was optimized at 550sim600°C with the insulating binder of 3wt%. As a result, the powder core showed the outstanding magnetic properties in terms of core loss and permeability, which were originated from the optimization of the grain size and distribution of the insulating binder.

Stability and Sedimentation Properties of TiO₂ Nanoparticles: S.H. Woo, M.K. Lee, C.K. Rhee; J Korean Powder Metall Inst. 2006;13(4):263-268.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.263

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In this study, the colloidal stability and sedimentation behavior of crystalline TiO_2 particles (300nm) in various organic solvents have been investigated by means of a backscattered light flux profile (Turbiscan). The backscattered light flux profiles revealed that the TiO_2 nanoparticles were readily sedimented in water, methyl alcohol, and ethyl alcohol due to a flocculation-induced particle growth, while a particle coalescence and a sedimentation of the TiO_2 nanoparticles were hardly observed in isopropyl alcohol. The migration velocities of the TiO_2 particle were measured as around 6.15/min, 12.53 m/min, 6.51m/min, and 0.18m/min for water, methyl alcohol, ethyl alcohol, and isopropyl alcohol, respectively, showing a remarkably slow migration of the TiO_2 particles in isopropyl alcohol.

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Effects of Viscosity on Dispersion Stability of Nano CoAl₂O₄ Ceramic Ink
Ji-Hyeon Lee, Hae-Jin Hwang, Jin-Ho Kim, Kwang-Taek Hwang, Kyu-Sung Han
Journal of the Korean Ceramic Society.2015; 52(6): 497. CrossRef

Reduction and Spark Plasma Sintering of the W(Tungsten) Nanopowder Produced by the Electric Explosion of Wire Process: Ji-Soon Kim, Cheol-Hee Kim, Eun-Ju Park, Young-Soon Kwon, Jin-Chun Kim, Sung-Ho Lee, Dong-Ik Jung; J Korean Powder Metall Inst. 2006;13(4):269-277.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.269

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Abstract PDF: [ beta-W(W_3O) ] oxide layer on the surface of each W(tungsten) nanopowder produced by the electric explosion of wire(EEW) process were formed during the 1vol.% air passivation process. The oxide layer hindered sintering densification of compacts during SPS process. The oxide phase was reduced to the pure W phase during SPS. The W nanopowder's compacts treated by the hydrogen reduction showed high sintered density of 94.5%. after SPS process at 1900°C.

Preparation of Ag Powder by Wet Reduction Method using NaBH₄ Reducing Agent: Chang-Whan Won, Huk-Hee Lee; J Korean Powder Metall Inst. 2006;13(4):278-284.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.278

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Abstract PDF: Spherical Ag powder was prepared in the system of AgNO_3;and;NaBH_4 by wet chemical reduction method. The size of Ag powder was increased as the reaction temperature and the concentration of reducing agent was decreased in the constant concentration of dispersion agent. Optimum conditions of producing Ag powder having 1.39µm of D50 was 1M of AgNO_3, 0.5M of NaBH_4, 1.5g of Gelatine in the room temperature.

Effect of Crystallization Treatment on the Magnetic Properties of Amorphous Strips Based on Co-Fe-Ni-B-Si-Cr Containing Nitrogen: H.J. Cho, H.T. Kwon, H.H. Ryu, K.Y. Sohn, B.S. You, W.W. Park; J Korean Powder Metall Inst. 2006;13(4):285-289.; DOI: https://doi.org/10.4150/KPMI.2006.13.4.285

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Abstract PDF: Co-Fe-Ni-B-Si-Cr based amorphous strips containing nitrogen were manufactured via melt spinning, and then devitrified by crystallization treatment at the various annealing temperatures of 300°Csim540°C for up to 30 minutes in an inert gas (N_2) atmosphere. The microstructures were examined by using XRD and TEM and the magnetic properties were measured by using VSM and B-H meter. Among the alloys, the amorphous ribbons of Co_72.6Fe_9.8Ni_5.5B_2.4Si_7.1Cr_2.6 containing 121 ppm of nitrogen showed relatively high saturation magnetization. The alloy ribbons crystallized at 540°C showed that the grain size of Co_72.6Fe_9.8Ni_5.5B_2.4Si_7.1Cr_2.6 alloy containing 121 ppm of nitrogen was about f nm, which exhibited paramagnetic behavior. The formation of nano-grain structure was attributed to the finely dispersed Fe4N particles and the solid-solutionized nitrogen atoms in the matrix. Accordingly, it can be concluded that the nano-grain structure of 5nm in size could reduce the core loss within the normally applied magnetic field of 300A/m at 10kHz.

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