Journal of Powder Materials

Jin-Woo Kim

6 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

20 View
0 Download
1 Citations

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.

Citations

Citations to this article as recorded by

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

28 View
0 Download
3 Citations

Abstract PDF

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.

Citations

Citations to this article as recorded by

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

11 View
0 Download

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

20 View
0 Download
3 Citations

Abstract PDF

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.

Citations

Citations to this article as recorded by

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

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

18 View
0 Download
6 Citations

Abstract PDF

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.

Citations

Citations to this article as recorded by

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

16 View
0 Download
1 Citations

Abstract PDF

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.

Citations

Citations to this article as recorded by

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

Author index