Journal of Powder Materials

Status and Prospect of Tungsten Resources and Tungsten Related Industries: Han-Shin Choi, Y.H. Kim, J.K. Lee; J Korean Powder Metall Inst. 2008;15(6):441-449.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.441

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The Current Status and Securing Strategies of Core Mineral Tungsten Resources
Dohyun Jeong, Seongmin Kim, Hoseok Jeon
Journal of the Korean Society of Mineral and Energy Resources Engineers.2023; 60(5): 341. CrossRef
Industrial Supply Chain Trend of Domestic Tungsten
Joon-Woo Song, Sang-Hyun Lee, Hyun-Seon Hong, Hong-Yoon Kang, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 79. CrossRef

Effect of Process Variables and exisisting Ions on Highly Active Nano-sized ITO Powders Prepared by Precipitation Method: In-Gyu Lee, Bong-Hyun Noh; J Korean Powder Metall Inst. 2008;15(6):450-457.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.450

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Abstract PDF: The objectives of this study were the development of a synthesis technique for highly active nanosized ITO powder and the understanding of the reaction mechanisms of the ITO precursors. The precipitation and agglomeration phenomena in ITO and In_2O_3 precursors are very sensitive to reaction temperature, pH, and coexisting ion species. Excessive Cl- ion and Sn+4 ions had a negative effect an synthesizing highly active powders. However, with a relevant stabilizing treatment the shape and size of ITO and In_2O_3 precursors could be controlled and high density sintered products of ITO were obtained. By applying the reprecipitation process (or stabilization technique), highly active ITO and In_2O_3 powders were synthesized. Sintering these powders at 1500°C for 5 hours produced 97% dense ITO bodies.

Microstructural Evolution during Hot Deformation of Molybdenum using Processing Map Approach: Young-Moo Kim, Sung-Ho Lee, Seong Lee, Joon-Woong Noh; J Korean Powder Metall Inst. 2008;15(6):458-465.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.458

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Abstract PDF: The hot deformation characteristics of pure molybdenum was investigated in the temperature range of 600sim1200°C and strain rate range of 0.01sim10.0/s using a Gleeble test machine. The power dissipation map for hot working was developed on the basis of the Dynamic Materials Model. According to the map, dynamic recrystallization (DRX) occurs in the temperature range of 1000sim1100°C and the strain rate range of 0.01sim10.0/s, which are the optimum conditions for hot working of this material. The average grain size after DRX is 5µm. The material undergoes flow instabilities at temperatures of 900sim1200°C and the strain rates of 0.01sim10.0/s, as calculated by the continuum instability criterion.

Using Nanosecond Electron Beam to Produce Silver Nanopowder: M.E. Balezin, O.R. Timoshenkova, S.Yu. Sokovnin, Hi-Min Lee, C.K. Rhee; J Korean Powder Metall Inst. 2008;15(6):466-470.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.466

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Experiments with a URT-0.5 accelerator (0.5 MeV, 50 ns, 1 kW) generating a nanosecond electron beam for irradiation of silver nitrate in various liquid solutions (water and toluene) were performed with the aim of producing silver nanopowders. A radiochemical reaction allows making weakly agglomerated pure Ag powders with particles of 10-15 nm and 30-50 nm in size by irradiation in toluene and water respectively. The injection of the nanosecond electron beam energy to the solution is optimal. As the absorbed dose increases, the output of the radiochemical reaction does not grow, but more agglomerated powders are synthesized.

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Application of nanosecond electron beam for production of silver nanopowders
M. E. Balezin, V. V. Bazarnyi, E. A. Karbovnichaya, S. Yu. Sokovnin
Nanotechnologies in Russia.2011; 6(11-12): 757. CrossRef

Microstructure Control and Magnetic Property of Nd-Fe-B Sintered Magnets After Cyclic Heat Treatment: Se-Hoon Kim, Hoon-Sup Kim, Dong-Hwan Kim, Young-Do Kim; J Korean Powder Metall Inst. 2008;15(6):471-476.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.471

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Sintered Nd-Fe-B magnets have been widely used due to their excellent magnetic properties, especially for driving motors of hybrid and electric vehicles. The microstructure of Nd-Fe-B magnets strongly affects their magnetic properties, in particular the coercivity. Therefore, a post-sintering process like heat-treatment is required for improving the magnetic properties of Nd-Fe-B sintered magnets. In this study, cyclic heat treatment was performed at temperatures between 350°C and 450°C up to 16 cycles in order to control microstructures such as size and shape of the Nd-rich phase without grain growth of the Nd_2Fe_14B phase. The 2 cycles specimen at this temperature range showed more homogeneous microstructure which leads to higher coercivity of 35 kOe than as-sintered one.

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Magnetic Properties and Sintering Behavior of (Nd,Dy)-Fe-B Permanent Magnet by Spark Plasma Sintering
Sun-Yong Song, Jin-Woo Kim, Se-Hoon Kim, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(2): 105. CrossRef
Pt and Polymer Electrolyte Membrane Fuel Cell
Hye-Sook Joo, Jung-Yeul Yun, Han-Shin Choi
Journal of Korean Powder Metallurgy Institute.2011; 18(1): 1. CrossRef
The Coercivity Enhancement of (Nd,Dy)-Fe-B Sintered Magnet by Microstructure Control
Jin-Woo Kim, Se-Hoon Kim, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2011; 18(1): 18. CrossRef
Magnetic properties of high coercivity Nd23Dy10Fe64TM2B1 sintered magnets by a convergent heat treatment
Hoon-sup Kim, Se Hoon Kim, Jin Woo Kim, Young Jung Lee, Dae-Gun Kim, Young Do Kim
Research on Chemical Intermediates.2010; 36(6-7): 859. CrossRef
Coercivity Enhancement of Nd23Dy10Fe64TM2B1Sintered Magnet by Convergent Heat Treatment
Hoon-Sup Kim, Se-Hoon Kim, Jin-Woo Kim, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(1): 1. CrossRef
Effects of thermal stress induced by cyclic heat treatment on sintered (Nd, Dy)-Fe-B magnets
Se Hoon Kim, Hoon-sup Kim, Young Jung Lee, Dae-Gun Kim, Young Do Kim
Metals and Materials International.2010; 16(6): 959. CrossRef

A Study on Manufacture of Spraying Powder for BSCCO Superconductor Formation by Plasma Spray: Jeong-Sik Park, Chang-Eun Cho, Kyung-Chae Park; J Korean Powder Metall Inst. 2008;15(6):477-481.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.477

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Abstract PDF: Formation and characteristics of spraying powder for BSCCO High-Tc superconductor prepared by plasma spray coating were investigated. The addition of 3% of binder gives the best flowability of the powder. Ball milling for 30h and 35h gives the best flowability of powder in the case of 2001 and 0212, respectively. The withdraw ratio increases upon binder addition from 12 to 27% in the case of 2001 and from 18 to 31% in the case of 0212 for sieving powder of 30-90µm in size. The built-up efficiency for 100µm thickness of spray coating is increased more than 30% by binder addition. The microstructure of the spray coated layers was investigated by XRD and EDS analysis.

Measurement of Hardness of Constituent Phases in Ti(C_0.7N_0.3)-NbC-Ni Cermets Using Nanoindentation: Seong-Won Kim, Dae-Min Kim, Shin-Hoo Kang, Sung-Soo Ryu, Hyung-Tae Kim; J Korean Powder Metall Inst. 2008;15(6):482-488.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.482

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Abstract PDF: The indentation technique has been one of the most commonly used techniques for the measurement of the mechanical properties of materials due to its experimental ease and speed. Recently, the scope of indentation has been enlarged down to the nanometer range through the development of instrumentations capable of continuously measuring load and displacement. In addition to testing hardness, the elastic modulus of submicron area could be measured from an indentation load-displacement (P-h) curve. In this study, the hardness values of the constituent phases in Ti(C_0.7N_0.3)-NbC-Ni cermets were evaluated by nanoindentation. SEM observation of the indented surface was indispensable in order to separate the hardness of each constituent phase since the Ti(C_0.7N_0.3)-based cermets have relatively inhomogeneous microstructure. The measured values of hardness using nanoindentation were sim20 GPa for hard phase and sim10 GPa for binder phase. The effect of NbC addition on hardness was not obvious in this work.

Synthesis of Tantalum Oxy-nitride and Nitride using Oxygen Dificiency Tantalum Oxides: Jong-Chul Park, Jae-Hwan Pee, Yoo-Jin Kim, Eui-Seock Choi; J Korean Powder Metall Inst. 2008;15(6):489-495.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.489

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Abstract PDF: Colored tantalum oxy-nitride (TaON) and tantalum nitride (Ta_3N_5) were synthesized by ammonolysis. Oxygen deficient tantalum oxides (TaO_1.7) were produced by a titration process, using a tantalum chloride (TaCl_5) precursor. The stirring speed and the amount of NH_4OH were important factors for controling the crystallinity of tantalum oxides. The high crystallinity of tantalum oxides improved the degree of nitridation which was related to the color value. Synthesized powders were characterized by XRD, SEM, TEM and Colorimeter.

Synthesis of Nano-size Aluminum Nitride Powders by Chemical Vapor Process: Jae-Hwan Pee, Jong-Chul Park, Yoo-Jin Kim, Kwang-Taek Hwang, So-Ryong Kim; J Korean Powder Metall Inst. 2008;15(6):496-502.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.496

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Aluminum nitride (AlN) powders were prepared by the chemical vapor synthesis (CVS) process in the AlCl_3-NH_3-N_2 system. Aluminum chloride (AlCl_3) as the starting material was gasified in the heating chamber of 300°C. Aluminum chloride gas transported to the furnace in NH_3-N_2 atmosphere at the gas flow rate of 200-400ml/min. For samples synthesized between 700 and 1200°C, the XRD peaks corresponding to AlN were comparatively sharp and also showed an improvement of crystallinity with increasing the reaction temperature. In additions, the average particle size of the AlN powders decreased from 250 to 40 nm, as the reaction temperature increased.

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A Scale-Up Test for Preparation of AlN by Carbon Reduction and Subsequent Nitridation Method
Hyung-Kyu Park, Sung-Don Kim, Chul-Woo Nam, Dae-Woong Kim, Moon-Soo Kang, Gwang-Hee Shin
Journal of the Korean Institute of Resources Recycling.2016; 25(5): 75. CrossRef
Synthesis of High Purity Aluminum Nitride Nanopowder in Ammonia and Nitrogen Atmosphere by RF Induction Thermal Plasma
Kyung-In Kim, Sung-Churl Choi, Jin-Ho Kim, Kwang-Taek Hwang, Kyu-Sung Han
Journal of the Korean Ceramic Society.2014; 51(3): 201. CrossRef
Synthesis of an aluminum nitride–yttria (AlN–Y2O3) composite from nano-sized porous AlN and YCl3
Jae-Hwan Pee, Jong-Chul Park, Kwang-Taek Hwang, SooRyong Kim, Woo-Seok Cho
Research on Chemical Intermediates.2010; 36(6-7): 801. CrossRef

Characterization of Ti(C,N) Solid Solutions in Densified Ti(C,N) and TiC-TiN-Ni Cermet: Seong-Won Kim, Jung-Min Chae, Shin-Hoo Kang, Sung-Soo Ryu, Hyung-Tae Kim; J Korean Powder Metall Inst. 2008;15(6):503-508.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.503

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Abstract PDF: Ti(C,N) solid solutions in hot-pressed Ti(C_xN_1-x) (x=0.0, 0.3, 0.5, 0.7, 1.0) and 40TiC-40TiN-20Ni (in wt.%) cermet were characterized in this study. For hot-pressed Ti(C,N)s, the lattice parameters and hardness values of Ti(C,N) were determined by using XRD (X-Ray Diffraction) and nanoindentation. The properties of hot-pressed Ti(C,N) samples changed linearly with their carbon or nitrogen contents. For the TiC-TiN-Ni cermet, the hardness of the hard phase and binder phase were determined by nanoindentation in conjunction with microstructural observation. The measured hardness values were sim8.7 GPa for the binder phase and sim28.7 GPa for the hard phase, which was close to the hardness of hot-pressed Ti(C_0.7N_0.3).

Manufacture and Application of Diamond Orifices in Abrasive Suspension Jet for Micro Machining: Youn-Chul Kim, Hee-Dong Park, Jae-Han Jho, Suk-Joong L Kang; J Korean Powder Metall Inst. 2008;15(6):509-513.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.509

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Abstract PDF: High-pressure abrasive entrained jet have rapidly become important machining technology over the last two decades. However, suspension jet by high-pressure has been recently developed for packaging sawing. Ideally, diamond materials should be used for components in abrasive water-jet systems that are subject to high erosive conditions. Using the diamond orifices improve maintenance and extend wear part life. This paper gives insights to using an abrasive suspension jet with diamond orifice. The influences of orifice material and orifice design are evaluated.

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