Journal of Powder Materials

Se-Hoon Kim

13 Articles

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; J Korean Powder Metall Inst. 2012;19(2):105-109.; DOI: https://doi.org/10.4150/KPMI.2012.19.2.105

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Magnetic properties and the microstructures of magnets prepared by spark plasma sintering were investigated in order to enhance magnetic properties by grain size control. Nd-Fe-B magnets were fabricated by the spark plasma sintering under 30 MPa at various temperatures. The grain size was effectively controlled by the spark plasma sintering and it was possible to make Nd-Fe-B magnets with grain size of 5.9 µm.

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Development of Fe-Mn-based Hybrid Materials Containing Nano-scale Oxides by a Powder Metallurgical Route
Jonggyu Jeon, Jungjoon Kim, Hyunjoo Choi
Journal of Korean Powder Metallurgy Institute.2020; 27(3): 203. CrossRef

Synthesis of Platinum Nanoparticles by Liquid Phase Reduction: Jin-Ho Lee, Se-Hoon Kim, Jin-Woo Kim, Min-Ha Lee, Young-Do Kim; J Korean Powder Metall Inst. 2012;19(1):60-66.; DOI: https://doi.org/10.4150/KPMI.2012.19.1.060

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In this study, Platinum(Pt) nanoparticles were synthesized by using polyol process which is one of the liquid phase reduction methods. Dihydrogen hexachloroplatinate (IV) hexahydrate (H_2PtCl_6cdot6H_2O), as a precursor, was dissolved in ethylene glycol and silver nitrate (AgNO_3) was added as metal salt for shape control of Pt particle. Also, polyvinylpyrrolidone (PVP), as capping agent, was added to reduce the size of particle and to separate the particles. The size of Pt nanoparticles was evaluated particle size analyzer (PSA). The size and morphology of Pt nanoparticles were observed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Synthesized Pt nanoparticles were studied with varying time and temperature of polyol process. Pt nanoparticles have been successfully synthesized with controlled sizes in the range 5-10 and 20-40 nm with cube and multiple-cube shapes.

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Facile Strategy for Mass Production of Pt Catalysts for Polymer Electrolyte Membrane Fuel Cells Using Low-Energy Electron Beam
Jongmin Shin, Jiho Min, Youngjin Kim, Jin Hee Lee, Geunseok Chai, Namgee Jung
Nanomaterials.2020; 10(11): 2216. CrossRef
Synthesis of Nanosized Nickel Particle from Spent Cathodic Material Containing Lithium
Jei-Pil Wang
Journal of Korean Powder Metallurgy Institute.2019; 26(4): 340. CrossRef
Fabrication and Characterization of Ag Particles by Polyol Process and Wet Chemical Process
Juyeon Yoo, Hyosung Jang, Kun-Jae Lee
Journal of Korean Powder Metallurgy Institute.2016; 23(4): 297. CrossRef

Fabrication of Gradient Porous Al-Cu Sintered Body: Jong-Min Byun, Se-Hoon Kim, Jin-Woo Kim, Young-Moon Kim, Young-Do Kim; J Korean Powder Metall Inst. 2011;18(4):365-371.; DOI: https://doi.org/10.4150/KPMI.2011.18.4.365

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Abstract PDF: In this study, gradient porous Al-Cu sintered body was fabricated by powder metallurgy processing. Al-Cu powder mixtures were prepared by low energy ball milling with various milling time. After ball milling for 3h, the shape of powder mixtures changed to spherical type with size of 100~500 µm. Subsequently, Al-Cu powder mixtures were classified (under 150, 150~300 and over 300 µm) and compacted (20, 50 and 100 MPa). Then, they were sintered at 600°C for various holding time (10, 30, 60 and 120 min) in N_2 atmosphere. The sintered bodies had 32~45% of porosity. As a result, the optimum holding time was determined to be 60 min at 600°C and sintered bodies with various porosity were obtained by controlling the compacting pressure.

The Coercivity Enhancement of (Nd,Dy)-Fe-B Sintered Magnet by Microstructure Control: Jin-Woo Kim, Se-Hoon Kim, Young-Do Kim; J Korean Powder Metall Inst. 2011;18(1):18-23.; DOI: https://doi.org/10.4150/KPMI.2011.18.1.018

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Sintered Nd-Fe-B magnets are widely used in many fields such as motors, generators, actuators, microwaves and so on due to their excellent magnetic properties. Many researchers have shown that the Nd-rich phase was essentially important for high magnet properties. In this study, we focused on controlling of the Nd-rich phase to enhance magnetic properties by the cyclic sintering process. Nd-Fe-B based sintered magnets were prepared by isothermal sintering and cyclic sintering processes. Magnetic properties and microstructure of the magnets were investigated. The coercivity was enhanced from 21.2 kOe to 23.27 kOe after 10 cycles of the sintering. The Nd-rich phase was effectively penetrated into the grain boundary between the Nd_2Fe_14B grains by the cyclic sintering.

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Effect of cyclic sintering process for NdFeB magnet on microstructure and magnetic properties
Jin Woo Kim, Sun Yong Song, Young Do Kim
Journal of Alloys and Compounds.2012; 540: 141. CrossRef
Transmission electron microscopy studies of sintered Nd-Fe-B magnets prepared by cyclic sintering
Jin Woo Kim, Se Hoon Kim, Sun Yong Song, Young Do Kim
Journal of Applied Physics.2012;[Epub] CrossRef
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

Fabrication of Ultra Fine Grained Molybdenum and Mechanical Properties: Se-Hoon Kim, Young-Ik Seo, Dae-Gun Kim, Myung-Jin Suk, Young-Do Kim; J Korean Powder Metall Inst. 2010;17(3):235-241.; DOI: https://doi.org/10.4150/KPMI.2010.17.3.235

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Abstract PDF: Mo nanopowder was synthesized by ball-milling and subsequent hydrogen-reduction of MoO_3 powder. To fabricate ultra fine grained molybdenum, two-step sintering and spark plasma sintering process were employed. The grain size of specimen by two-step sintering and spark plasma sintering was around 0.6;µm and 0.4;µm, respectively. Mechanical properties of ultra fine grained Mo with relative density of above 90% were significantly improved at room and high temperatures comparing to commercial bulk Mo of 99% relative density. This result was mainly explained by the grain size refinement due to diffusion-controlled sintering.

Sintering Behavior and Phase Analysis of (Nd, Dy)-Fe-B Powder: Se-Hoon Kim, Jin-Woo Kim, Young-Do Kim; J Korean Powder Metall Inst. 2010;17(2):154-159.; DOI: https://doi.org/10.4150/KPMI.2010.17.2.154

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In this study, the sintering behavior of (Nd, Dy)-Fe-B powder which fabricated by strip-casting was investigated with various sintering temperatures and holding times. The relative density over 99% could be obtained by both sintering at 1070°C for 1h and sintering at 970°C for 20h. The grain growth was observed in sintered specimen at 1050°C compared to one at 970°C. The isothermal sintering process below 1000°C led to suppress grain growth showing the improved magnetic properties. The phase transformation of Nd-rich was confirmed by X-ray diffraction pattern.

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Crystallographic and Mössbauer studies of sintered Nd-Fe-B magnet
Yong Hui Li, Jung Tae Lim, Chul Sung Kim, Sung Yong An, Kang Ryong Choi, Moonhee Choi
Journal of the Korean Physical Society.2013; 62(11): 1641. CrossRef
Mechanical properties of (Nd,Dy)–Fe–B magnets sintered via cyclic sintering
Jin Woo Kim, Se Hoon Kim, Young Do Kim
Materials Science and Engineering: A.2012; 535: 325. CrossRef
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
High coercive Nd–Fe–B magnets fabricated via two-step sintering
Se Hoon Kim, Jin Woo Kim, Tae Sun Jo, Young Do Kim
Journal of Magnetism and Magnetic Materials.2011; 323(22): 2851. 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

Coercivity Enhancement of Nd₂₃Dy₁₀Fe₆₄TM₂B₁ Sintered Magnet by Convergent Heat Treatment: Hoon-Sup Kim, Se-Hoon Kim, Jin-Woo Kim, Young-Do Kim; J Korean Powder Metall Inst. 2010;17(1):1-6.; DOI: https://doi.org/10.4150/KPMI.2010.17.1.001

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In this study, a convergent heat treatment was performed in certain temperature regions in order to control the microstructures of Nd-rich phases and to reduce thermal stress on grain boundaries which could be caused during expansion and shrinkage of Nd-rich and Nd_2Fe_14B phases. The difference of thermal expansion coefficient between Nd_2Fe_14B and Nd-rich phases is the mechanism for convergent heat treatment. The Nd-rich phases which were located in junctions could penetrate into the grain boundaries between Nd_2Fe_14B phases due to the difference of thermal expansion coefficient. Through the convergent heat treatment, the microcracks that were observed in cyclic heat treatment were not observed and coercivity was increased to 34.05 kOe at 8 cycles.

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Sintering Behavior and Phase Analysis of (Nd, Dy)-Fe-B Powder
Se-Hoon Kim, Jin-Woo Kim, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(2): 154. CrossRef

Warm Compaction of Fe-Si/Fe Powder Mixture and its Magnetic Property: Se-Hoon Kim, Myung-Jin Suk, Young-Do Kim; J Korean Powder Metall Inst. 2009;16(4):249-253.; DOI: https://doi.org/10.4150/KPMI.2009.16.4.249

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Abstract PDF: 3-D shape soft magnetic composite parts can be formed by general compaction method of powder metallurgy. In this study, the results on the high density nanostructured Fe-Si/Fe composite prepared by a warm compaction method were presented. Ball-milled Fe-25 wt.%Si powder, pure Fe powder and Si-polymer were mixed and then the powder mixture was compacted at various temperatures and pressures. Pore free density of samples up to 95% theoretical value has been obtained. The warm compacted sample prepared at 650 MPa and 240°C had highest compaction properties in comparison with other compacts prepared at 300, 400 MPa and room temperature and 120°C. The magnetic properties such as core loss, magnetization saturation and coercivity were measured by B-H curve analyzer and vibration sample magnetometer.

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

Production and Application of Nd-Fe-B Sintered Magnets: Se-Hoon Kim, Young-Do Kim, Tae-Suk Jang; J Korean Powder Metall Inst. 2008;15(4):263-270.; DOI: https://doi.org/10.4150/KPMI.2008.15.4.263

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A novel composite hot-extruded Nd-Fe-B permanent magnetic ring
Yajing Li, Siyuan Zuo, Liyun Zheng, Minggang Zhu, Yikun Fang, Lixin Zhao, Chenglin Li, Wei Li, George C. Hadjipanayis
Journal of Magnetism and Magnetic Materials.2023; 577: 170781. CrossRef
Sintering Behavior and Phase Analysis of (Nd, Dy)-Fe-B Powder
Se-Hoon Kim, Jin-Woo Kim, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(2): 154. CrossRef
Trend in Research and Development Related to Sm-Fe-N Bonded Magnets
Jung-Goo Lee, Hun Kwak, Chul-Jin Choi, Joon-Chul Yun, Jai-Sung Lee
Journal of Korean Powder Metallurgy Institute.2009; 16(1): 1. CrossRef

Magnetic Properties of Fe Powder Core Fabricated by Warm Compaction: Se-Hoon Kim, Tae-Sun Jo, Min-Suh Park, Young-Do Kim; J Korean Powder Metall Inst. 2007;14(5):298-302.; DOI: https://doi.org/10.4150/KPMI.2007.14.5.298

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In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.

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Warm Compaction of Fe-Si/Fe Powder Mixture and its Magnetic Property
Se-Hoon Kim, Myung-Jin Suk, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2009; 16(4): 249. CrossRef

Compaction Properties of Fe Powder Fabricated by Warm Compaction: Se-Hoon Kim, Young-Jung Lee, Jea-Sung Lee, Young-Do Kim; J Korean Powder Metall Inst. 2007;14(3):185-189.; DOI: https://doi.org/10.4150/KPMI.2007.14.3.185

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Abstract PDF: Various approaches have been proposed to increase the green density. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effect of warm compaction on green density of Fe powder was investigated. After ball-milling of Fe oxide powder for 30 hours, Fe oxide powder was reduced through the hydrogen reduction process. The pure Fe powder and polymer binder were mixed by 3-D tubular mixer. And then the mixed powder was warm-compacted with various compaction pressure and binder contents. The green density of specimen was added polyvinyl binder was higher than any other specimens.

Effect of Grain Size on Nanostructured Fe-20 wt.%Si Alloy Powders Produced by High-energy ball milling: Se-Hoon Kim, Young Jung Lee, Baek-Hee Lee, Kyu Hwan Lee, Young Do Kim; J Korean Powder Metall Inst. 2005;12(5):362-368.; DOI: https://doi.org/10.4150/KPMI.2005.12.5.362

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Abstract PDF: The structural and magnetic properties of nanostructued Fe-20 ;wt.%Si alloy powders were investigated. Commercial Fe-20 wt.%Si alloy powders (Hoeganaes Co., USA) with 99.9% purities were used to fabricate the nanostructure Fe-Si alloy powders through a high-energy ball milling process. The alloy powders were fabricated at 400 rpm for 50 h, resulting in an average grain size of 16 nm. The nanostructured powder was characterized by fcc Fe_3Si and hcp Fe_5Si_3 phases and exhibited a minimum coercivity of approximately 50 Oe.

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