Journal of Powder Materials

Yong-Ho Park

7 Articles

[Korean]
Preparation of Metal Injection Molded Dental Components using Spheroidized Ti Powders by Plasma Process: Ji-Na Gwak, Sangsun Yang, Jung-Yeul Yun, Ju-Yong Kim, Seongjin Park, Hyun-Seung Kim, Yong-Jin Kim, Yong-Ho Park; J Korean Powder Metall Inst. 2013;20(6):467-473.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.467

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This research presents a preparation method of dental components by metal injection molding process (MIM process) using titanium scrap. About 20µm sized spherical titanium powders for MIM process were successfully prepared by a novel dehydrogenation and spheroidization method using in-situ radio frequency thermal plasma treatment. The effects of MIM process parameters on the mechanical and biological properties of dental components were investigated and the optimum condition was obtained. After sintering at 1250°C for 1 hour in vacuum, the hardness and the tensile strength of MIMed titanium components were 289 Hv and 584 MPa, respectively. Prepared titanium dental components were not cytotoxic and they showed a good cell proliferation property.

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Effect of Heat Treatment Temperature and Atmosphere on the Microstructure of TiH2-WO3 Powder Mixtures
Han-Eol Lee, Yeon Su Kim, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2017; 24(1): 41. CrossRef
Characterization Of The Graded Microstructure In Powder Sintered Porous Titanium
J.-J. Oak, J.I. Bang, K.-C. Bae, Y.H. Kim, Y.-C. Lee, H.H. Chun, Y.H. Park
Archives of Metallurgy and Materials.2015; 60(2): 1265. CrossRef

[Korean]
Influence of Particle Size Distribution on Green and Sintered Properties of Fe-Cr-Mo Prealloy Powder: Ki-Bong Kim, Sangsun Yang, Yong-Jin Kim, Yong-Ho Park; J Korean Powder Metall Inst. 2013;20(1):7-12.; DOI: https://doi.org/10.4150/KPMI.2013.20.1.007

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The effect of particle size distribution on green and sintered properties of Fe-Cr-Mo prealloy powder was investigated in this study. For the study, prealloyed Fe-Cr-Mo powders with different particle sizes were mixed as various ratios and cold compacted at various pressure and sintered at 1250°C for 30 min, 90%N_2+10%H_2 atmosphere in the continuous sintering furnace. The results shows that the powders with large particle size distribution have high compressibility and low ejection force. However the green strength are much less than those with small particle size distribution. Tensile prperties of the sintered specimes with large particles size also have high strength and elongation.

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The Effects of MoS2Addition on the Mechanical Properties of Fe-Cr-Mn-C-V P/M Alloy
Geon-Hong Kim, Hyun Seok Yang, Man-Sik Kong
Journal of Korean Powder Metallurgy Institute.2014; 21(4): 294. CrossRef
Investigation on the Sintering Behavior and Mechanical Properties of Al-Zn-Mg Alloy Powders Mixed with Al-Si-SiC Composite Powders
Gwang-Joo Jang, Kyung Tae Kim, Sangsun Yang, Yong-Jin Kim, Yong-Ho Park
Journal of Korean Powder Metallurgy Institute.2014; 21(6): 460. CrossRef

[Korean]
Effect of Milling Time on the Microstructure and Phase Transformation Behaviors of Ni-B Powder During Mechanical Alloying Process: Jung-Geun Kim, Wook-Jin Lee, Sung-Kyun Park, Ik-Min Park, Yong-Ho Park; J Korean Powder Metall Inst. 2011;18(6):496-501.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.496

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Abstract PDF: In this study, the effect of milling time on the microstructure and phase transformation behaviors of Ni-12 wt.%B powders was investigated using vibratory ball milling process. X-ray diffraction patterns showed that the phase transformation of mixed Ni-B elemental powder occurred after 50 hours of milling, with a formation of nickel boride phases. Through the study of microstructures in mechanical alloying process, it was considered that ball milling strongly accelerates solid-state diffusions of the Ni and B atoms during mechanical alloying process. The results of X-ray photoelectron spectroscopy showed that most of B atoms in the powder were linked to Ni with a formation of nickel boride phases after 200 hours of milling. It was finally concluded that mechanical alloying using ball milling process is feasible to synthesize fine and uniform nickel boride powders.

[Korean]
Synthesis of Nano-sized Tungsten Carbide - Cobalt Powder by Liquid Phase Method of Tungstate: Jong-Hoon Kim, Yong-Ho Park, Gook-Hyun Ha; J Korean Powder Metall Inst. 2011;18(4):332-339.; DOI: https://doi.org/10.4150/KPMI.2011.18.4.332

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Cemented tungsten carbide has been used in cutting tools and die materials, and is an important industrial material. When the particle size is reduced to ultrafine, the hardness and other mechanical properties are improved remarkably. Ultrafine cemented carbide with high toughness and hardness is now widely used. The objective of this study is synthesis of nanostructured WC-Co powders by liquid phase method of tungstate. The precursor powders were obtained by freezen-drying of aqueous solution of soluble salts, such as ammonium metatungstate, cobalt nitrate. the final compositions were WC-10Co. In the case of liquid phase method, it can be observed synthesis of WC-10Co. The properties of powder produced at various temperature, were estimated from the SEM, BET and C/S analyser.

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Development of a new nanocrystalline alloy for X-ray shielding
J. H. Cho, H. K. Lee, M. S. Kim, J. D. Rhim, Y. J. Park
Radiation Effects and Defects in Solids.2018; 173(7-8): 643. CrossRef
Study on dispersibility of thermally stable carbon black particles in ink using asymmetric flow field-flow fractionation (AsFlFFF)
Woonjung Kim, Jihyun Bae, Chul Hun Eum, Jongjin Jung, Seungho Lee
Microchemical Journal.2018; 142: 167. CrossRef
Surface Modification of Carbon Black Using Polymer Resin Synthesized by a Phenyl Radical Reaction
Seungho Lee, Chul Hun Eum, Woon Jung Kim
Journal of the Korean Chemical Society.2016; 60(4): 286. CrossRef
Improvement in Mechanical and Wear Properties of WC-Co by Ultrasonic Nanocrystal Surface Modification Technique
Seung-Chul Lee, Jun-Hyong Kim, Gab-Su Choi, Young-Do Jang, Auezhan Amanov, Young-Sik Pyun
Journal of the Korean Society of Tribologists and Lubrication Engineers.2015; 31(2): 56. CrossRef
Changes in Mechanical Properties of WC-Co by Ultrasonic Nanocrystal Surface Modification Technique
Seung-Chul Lee, Jun-Hyong Kim, Hak-Doo Kim, Gab-Su Choi, Auezhan Amanov, Young-Sik Pyun
Journal of the Korean Society of Tribologists and Lubrication Engineers.2015; 31(4): 157. CrossRef

[Korean]
Influence of Boron Content on the Thermoelectric Properties of p-type Si_0.8Ge_0.2 Alloy: Sung-Doo Hwang, Woo-Suk Choi, Ik-Min Park, Yong-Ho Park; J Korean Powder Metall Inst. 2007;14(4):272-276.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.272

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Abstract PDF: P-type thermoelectric material Si_0.8Ge_0.2 was sintered by Hot Press process (HP) and the effect of boron (0.25sim2 at%) addition on the thermoelectric properties were reported. To enhance the thermoelectric performances, the Si_0.8Ge_0.2, alloys were fabricated by mechanical alloying (MA) and HP. The carrier of p-type SiGe alloy was controlled by B-doping. The effect of sintering condition and thermoelectric properties were investigated. B-doped SiGe alloys exhibited positive seebeck coefficient. The electrical conductivity and thermal conductivity were increased at the small amount of boron content (0.25sim0.5 at%). However, they were decreased over 0.5 at% boron content. As a result, the small addition of boron improved the Z value. The Z value of 0.5 at% B doped Si_0.8Ge_0.2 B alloy was 0.9times10-4/K, the highest value among the prepared alloys.

[Korean]
Complex Forming of the High-Functional Intermetallic Compound by the In Process Synthesis: Jung-Hyun Han, Seong-Kab Park, Yong-Ho Park; J Korean Powder Metall Inst. 2006;13(6):408-414.; DOI: https://doi.org/10.4150/KPMI.2006.13.6.408

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Abstract PDF: [ MoSi_2 ] alloys with Al, B or Nb were prepared by an advanced consolidation process that combined mechanical alloying with pulse discharge sintering (complex forming) to improve the mechanical properties. Their microstructure and mechanical properties were investigated. The MoSi_2 alloys fabricated by complex forming method showed very fine microstructure when compared with the sample sintered from commercial MoSi_2 powders. Alloys made from powders milled in Ar gas had fewer silica or alumina phases as compared to their counterparts sintered from powders milled in air. In densification of the sintered body, addition of B was more effective than Al or Nb. Both Victors hardness and tensile test indicated that the alloy fabricated by the complex forming method showed better properties than the sample sintered from commercial MoSi_2 powders. The Al added alloy sintered from the powders milled in air had the superior mechanical properties due to the suppression of SiO_2 and formation of fine Al_2O_3 particles.

[Korean]
Effect of Heat Treatment on the Microstructure and Mechanical Properties for Al-Si Alloyed Powder Material by Gas Atomizing and Hot Extrusion Process: Ki-Young Nam, Hyeong-Ho Jin, Yong-Jin Kim, Seog-Young Yoon, Yong-Ho Park; J Korean Powder Metall Inst. 2006;13(6):421-426.; DOI: https://doi.org/10.4150/KPMI.2006.13.6.421

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Abstract PDF: The microstructural and mechanical properties of Al-Si alloyed powder, prepared by gas atomization fallowed by hot extrusion, were studied by optical and scanning electron microscopies, hardness and wear testing. The gas atomized Al-Si alloy powder exhibited uniformly dispersed Si particles with particle size ranging from 5 to 8µm. The hot extruded Al-Si alloy shows the average Si particle size of less than 1µm. After heat-treatment, the average particle size was increased from 2 to 5µm. Also, mechanical properties of extruded Al-Si alloy powder were analyzed before and after heat-treatment. As expected from the microstructural analysis, the heat-treated samples resulted in a decrease in the hardness and wear resistance due to Si particle growth. The friction coefficient of heat-treated Al-Si alloyed powder showed higher value tough all sliding speed. This behavior would be due to abrasive wear mechanism. As sliding speed increases, friction coefficient and depth and width of wear track increase. No significant changes occurred in the wear track shape with increased sliding speed.

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