Journal of Powder Materials

C.K. Rhee

13 Articles

Tribology Properties of Nanodiamond Dispersed Engine Oil: S.H. Jun, Y.R Uhm, C.K. Rhee; J Korean Powder Metall Inst. 2011;18(5):417-422.; DOI: https://doi.org/10.4150/KPMI.2011.18.5.417

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Hydrophobic nanodiamond (ND) were dispersed in engine oil (Helix Oil, Shell co.) as an additives to improve tribology properties. In this study, nanodiamond prepared by an explosive method was used. Tribology properties of both pure Helix oil and engine oil containing ND additive were evaluated. The rotating disks were made of Gray Cast Iron (240 Hv) and SKD11 (710 Hv). Surface topographies of the disks' wear tracks and friction coefficient were compared. The results show that nanodiamond-dispersed lubricants are capable of reducing these metals' wear loss. The friction coefficient is strongly affected to the hardness of wear track.

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Wear Characteristics of Lubricant with Nano-diamond Particles on Al-6061 Aluminum Alloy
Sung-Wan Hwang
Journal of the Korean Society of Manufacturing Process Engineers.2021; 20(12): 16. CrossRef
Tribological properties of nanodiamonds in aqueous suspensions: effect of the surface charge
Zijian Liu, Dustin Leininger, Amir Koolivand, Alex I. Smirnov, Olga Shenderova, Donald W. Brenner, Jacqueline Krim
RSC Advances.2015; 5(96): 78933. CrossRef

Comparative Analyses of Commercial Detonation Nanodiamonds: A.P. Puzyr, A.E. Burova, V.S. Bondar, C.K. Rhee, W.H. Rhee, K.C. Hwang; J Korean Powder Metall Inst. 2011;18(3):297-302.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.297

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Colloidal stability is one of crucial factors for many applications of nanodiamond. Despite recent development, nanodiamonds available on the market often exhibit a high impurity content, wide size distribution of aggregates and low resistance to sedimentation. In the current study, four commercial nanodiamond powders synthesized by detonation synthesis were surface modified and then separated with respect to the size into six fractions by centrifugation. The fractions were evaluated by zeta potential, particle size distribution and elemental composition. The results showed that the modified nanodiamonds form stable colloidal suspensions without sedimentation for a long time.

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Production, surface modification, physicochemical properties, biocompatibility, and bioimaging applications of nanodiamonds
Tirusew Tegafaw, Shuwen Liu, Mohammad Yaseen Ahmad, Abdullah Khamis Ali Al Saidi, Dejun Zhao, Ying Liu, Huan Yue, Sung-Wook Nam, Yongmin Chang, Gang Ho Lee
RSC Advances.2023; 13(46): 32381. CrossRef
Tribology Properties of Nanodiamond Dispersed Engine Oil
S.H. Jun, Y.R Uhm, C.K. Rhee
Journal of Korean Powder Metallurgy Institute.2011; 18(5): 417. CrossRef

One-step Physical Method for Synthesis of Cu Nanofluid in Ethylene Glycol: L.H. Bac, K.S. Yun, J.S. Kim, J.C. Kim, C.K. Rhee; J Korean Powder Metall Inst. 2010;17(6):464-469.; DOI: https://doi.org/10.4150/KPMI.2010.17.6.464

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The Cu nanofluid in ethylene glycol was prepared by electrical explosion of wire, a novel one-step method. The X-ray diffraction, field emission scanning electron microscope and transmission electron microscope were used to study the properties of Cu nanoparticles. The results showed that the nanoparticles were consisted of pure face-centered cubic structure and near spherical shape with average grain size of 65 nm. Ultraviolet-visible spectroscopy (UV-Vis) confirmed Cu nanoparticles with a single absorbance peak of Cu surface plasmon resonance band at 600 nm. The nanofluid was found to be stable due to high positive zeta potential value, +51 mV. The backscattering level of nanofluid in static stationary was decreased about 2% for 5 days. The thermal conductivity measurement showed that Cu-ethylene glycol nanofluid with low concentration of nanoparticles had higher thermal conductivity than based fluid. The enhancement of thermal conductivity of nanofluid at a volume fraction of 0.1% was approximately 5.2%.

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Enhanced heat transfer of laser-fabricated copper nanofluid at ultra-low concentration driven by the nanoparticle surface area
S. Khamlich, J. Jakobi, T. Khamliche, F. Ismail, O. Nemraoui, C. Rehbock, V. Fester, S. Barcikowski
Journal of Molecular Liquids.2023; 383: 122104. CrossRef
Preparation and thermophysical study on a super stable copper oxide/deep eutectic solvent nanofluid
Changhui Liu, Yu Yan, Wenjie Sun, Xiancong Shi, Ningyu Shi, Yixuan Huo, Jiateng Zhao, Zafar Said, Mohsen Sharifpur
Journal of Molecular Liquids.2022; 356: 119020. CrossRef
Electroexplosive Technology of Nanopowders Production: Current Status and Future Prospects
Young-Soon Kwon, Jin-Chun Kim, Alexander P. Ilyin, Olga B. Nazarenko, Dmitry V. Tikhonov
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 40. CrossRef
Effect of Electrical Parameters and Surrounding Gas on the Electroexplosive Tungsten Nanopowders Characteristics
Young-Soon Kwon, Jin-Chun Kim, Alexander P. Ilyin, Olga B. Nazarenko, Dmitry V. Tikhonov
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 49. CrossRef
Characterization and Stability of Silver Nanoparticles in Aqueous Solutions
L.H. Bac, W.H. Gu, J.C. Kim, B.K. Kim, J.S. Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 55. CrossRef

Synthesis of Core/shell Structured Ag/C Nano Particles and Properties on Annealing Conditions: S.H. Jun, Y.R. Uhm, C.K. Rhee; J Korean Powder Metall Inst. 2010;17(4):295-301.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.295

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Multi shell graphite coated Ag nano particles with core/shell structure were successfully synthesized by pulsed wire evaporation (PWE) method. Ar and CH_4 (10 vol.%) gases were mixed in chamber, which played a role of carrier gas and reaction gas, respectively. Graphite layers on the surface of silver nano particles were coated indiscretely. However, the graphite layers are detached, when the particles are heated up to 250°C in the air atmosphere. In contrast, the graphite coated layer was stable under Ar and N_2 atmosphere, though the core/shell structured particles were heated up to 800°C. The presence of graphite coated layer prevent agglomeration of nanoparticles during heat treatment. The dispersion stability of the carbon coated Ag nanoparticles was higher than those of pure Ag nanoparticles.

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Fabrication of Carbon-coated Tin Nano-powders by Electrical Wire Explosion in Liquid Media and its Electrochemical Properties
Yoo-Young Kim, Ju-Suck Song, Kwon-Koo Cho
Journal of Korean Powder Metallurgy Institute.2016; 23(4): 317. CrossRef
Study of Mössbauer Spectroscopy for Iron Oxides Synthesized by Pulsed Wire Evaporation (PEW)
Young Rang Uhm
Journal of the Korean Magnetics Society.2014; 24(5): 135. CrossRef

Fabrication and Characterization of Carbon-Coated Cu Nanopowders by Pulsed Wire Evaporation Method: H.M. Lee, J.H. Park, S.M. Hong, Y.R. Uhm, C.K. Rhee; J Korean Powder Metall Inst. 2009;16(4):243-248.; DOI: https://doi.org/10.4150/KPMI.2009.16.4.243

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Carbon-coated Cu nanopowders with core/shell structure have been successfully fabricated by pulsed wire evaporation (PWE) method, in which a mixed gas of Ar/CH_4 (10 vol.%) was used as an ambient gas. The characterization of the samples was carried out using x-ray diffraction (XRD), scanning electron microscope (SEM), and high resolution transmission electron microscope (HRTEM). It was found that the nanoparticles show a spherical morphology with the size ranging of 10-40 nm and are covered with graphite layers of 2-4 nm. When oxygen-passivated Cu nanopowders were annealed under flowing argon gas (600 and 800°C), the crystallinity of Cu_2O phase and the particle size gradually increased. On the other hand, carbon-coated Cu nanopowders remained similar to as-prepared case with no additional oxide or carbide phases even after the annealing, indicating that the metal nanoparticles are well protected by the carbon-coating layers.

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Improved oxidation stability of carbon-coated Ni nanoparticles synthesized by one-step electrical wire explosion
Jun-Hyeok Lee, Byung-Hoon Kim, Gyoung-Ja Lee
Materials Chemistry and Physics.2022; 276: 125410. CrossRef
Fabrication of Ni-free Fe-based Alloy Nano Powder by Pulsed Wire Evaporation in Liquid: Part I. Effect of Wire Diameter and Applied Voltage
Ho-Jin Ryu, Yong-Heui Lee, Kwang-Ug Son, Young-Min Kong, Jin-Chun Kim, Byoung-Kee Kim, Jung-Yeul Yun
Journal of Korean Powder Metallurgy Institute.2011; 18(2): 105. CrossRef
A Study on Thermal Properties of Ethylene Glycol Containing Copper Oxide Nanoparticles
Chang-Kyu Kim, Gyoung-Ja Lee, Chang-Kyu Rhee
Journal of Korean Powder Metallurgy Institute.2010; 17(4): 276. CrossRef
Synthesis and Characterization of Cu Nanofluid Prepared by Pulsed Wire Evaporation Method
Chang-Kyu Kim, Gyoung-Ja Lee, Chang-Kyu Rhee
Journal of Korean Powder Metallurgy Institute.2010; 17(4): 270. CrossRef
Synthesis of Core/shell Structured Ag/C Nano Particles and Properties on Annealing Conditions
S.H. Jun, Y.R. Uhm, C.K. Rhee
Journal of Korean Powder Metallurgy Institute.2010; 17(4): 295. CrossRef
Synthesis and Characterization of Glold Nanofluid Prepared by the Solution Plasma Processing
Yong-Kang Heo, Sang-Yul Lee
Journal of Korean Powder Metallurgy Institute.2010; 17(4): 342. CrossRef

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

Consolidation of Segment Powder for Diamond Tool by Magnetic Pulsed Compaction: J.S. Yun, J.G. Lee, M.K. Lee, C.K. Rhee, M.S. Park, S.J. Hong; J Korean Powder Metall Inst. 2008;15(5):378-385.; DOI: https://doi.org/10.4150/KPMI.2008.15.5.378

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This article presents the successful consolidation of the mixed Co and Diamond powders for a drilling segment by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were analyzed. Homogeneous hardness (Hv 220) and density (97%) of sintered bulks fabricated by MPC were obtained by the new technique, where higher pressure has been employed for short period of time than that of general process. A fine microstructure and homogeneous hardness in the consolidated bulk were observed without cracks. Relatively higher drilling speed of 9.61 cm/min and life time of 6.55 m were found to the MPCed specimens, whereas the value of the specimens fabricated by general process was 11.71 cm/min and 7.96 m, respectively. A substantial improvement of mechanical properties of segment was achieved through this study.

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Machining Characteristics of Micro Structure using Single-Crystal Diamond Tool on Cu-plated Mold
Chang-Eui Kim, Eun-chae Jeon, Tae-Jin Je, Myung Chang Kang
Journal of Korean Powder Metallurgy Institute.2015; 22(3): 169. CrossRef
Comparison of Micro Trench Machining Characteristics with Nonferrous Metal and Polymer using Single Diamond Cutting Tool
Hwan-Jin Choi, Eun-Chae Jeon, Doo-Sun Choi, Tae-Jin Je, Myung-Chang Kang
Journal of Korean Powder Metallurgy Institute.2013; 20(5): 355. CrossRef
Comparison of Machinability Between PCD Tool and SCD Tool for Large Area Mirror Surface Machining Using Multi-tool by Planer
Chang-Eui Kim, Hwan-Jin Choi, Eun-Chae Jeon, Tae-Jin Je, Myung-Chang Kang
Journal of Korean Powder Metallurgy Institute.2013; 20(4): 297. CrossRef
Consolidation of mixed diamond and cobalt granule powders by magnetic pulsed compaction
Jung G. Lee, M.K. Lee, S.J. Hong, H.W. Lee, S.P. Pyun, C.K. Rhee
Materials Letters.2010; 64(1): 35. CrossRef

Densification of Al₂O₃ Nanopowder by Magnetic Pulsed Compaction and Their Properties: R.C. Kang, M.K. Lee, W.W. Kim, C.K. Rhee, S.J. Hong; J Korean Powder Metall Inst. 2008;15(1):37-45.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.037

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This article presents the challenges toward the successful consolidation of Al_2O_3 nanopowder using magnetic pulsed compaction (MPC). In this research the ultrafine-structured Al_2O_3 bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were investigated. The obtained density of Al_2O_3 bulk prepared by the combined processes was increased with increasing MPC pressure from 0.5 to 1.25 GPa. Relatively higher hardness and fracture toughness in the MPCed specimen at 1.25 GPa were attributed to the retention of the nanostructure in the consolidated bulk without cracks. The higher fracture toughness could be attributed to the crack deflection by homogeneous distribution and the retention of nanostructure, regardless of the presence of porosities. In addition, the as consolidated Al_2O_3 bulk using magnetic pulsed compaction showed enhanced breakdown voltage.

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Microstructure and Characteristics of Ag-SnO2Contact Materials Prepared by Magnetic Pulsed Compaction
J.S. Park, Y.J. Kim, M.H. Lee, H.S. Lee, S.J. Hong, J.K. Lee
Journal of Korean Powder Metallurgy Institute.2011; 18(4): 372. CrossRef
The Effect of Ti Powder addition on Compaction Behavior of TiO2Nano Powder
Jin-Sub Park, Hyo-Seob Kim, Ki-Seok Lee, Jeong-Goo Lee, Chang-Kyu Rhee, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2009; 16(3): 223. CrossRef

Effect of Alumina Nanooxide Application on Nitrendipine Manufacturing Process: E.J. Chae, Y.R. Uhm, B.S. Han, C.K. Rhee, S.E. Park; J Korean Powder Metall Inst. 2007;14(2):127-131.; DOI: https://doi.org/10.4150/KPMI.2007.14.2.127

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Abstract PDF: The alumina nano powders synthesized by levitational gas condensation (LGC) method were applied to catalyst in manufacturing process of Hanzsch reaction for Nitrendipine. The L-tartaric acid on the surface is carried out with participation of carbonyl fragments, O-H, C-H bonds which affects stereo selectivity, yield on the reagents positively. From the analysis of the IR-spectroscopy, the carbonyl fragments, O-H, and C-H bond were created by the catalytic reaction. From the analysis of the rR-spectroscopy, the carbonyl fragments, O-H, and C-H bond were created by the catalytic reaction. The newly created bonds made a chiral center on the final product.

An Investigation of Dispersion Behavior of Y₂O₃ Ceramic Particles in Hypo, Eutectic and Hyper Binary Al-Cu Cast Alloys: J.J. Park, G.H. Kim, S.M. Hong, S.H. Lee, M.K. Lee, C.K. Rhee; J Korean Powder Metall Inst. 2007;14(2):123-126.; DOI: https://doi.org/10.4150/KPMI.2007.14.2.123

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Abstract PDF: In this work, the dispersion behavior of Y_2O_3 particles in binary aluminum (Al)-copper (Cu) cast alloy was investigated with respect to Cu contents of 20 (hypoeutertic), 33 (eutectic) and 40 (hypereutectic) wt.%. In cases of hypo and hypereutectic compositions, SEM images revealed that the primary Al and theta phases were grown up at the beginning, respectively, and thereafter the eutectic phase was solidified. In addition, it was found that some of Y_2O_3 particles can be dispersed into the primary Al phase, but none of them are is observed inside the primary 6 phase. This different dispersion behavior of Y_2O_3 particles is probably due to the difference in the val- ues of specific gravity between Y_2O_3 particles and primary phases. At eutectic composition, Y_2O_3 particles were well dispersed in the matrix since there is few primary phases acting as an impediment site for particle dispersion during solidification. Based on the experimental results, it is concluded that Y_2O_3 particles are mostly dispersed into the eutectic phase in binary Al-Cu alloy system.

Study of Mechanically Alloyed Nano Cu-Fe Particles With a Hetero-Structure: Y.R. Uhm, H.M. Lee, C.K. Rhee; J Korean Powder Metall Inst. 2007;14(2):97-100.; DOI: https://doi.org/10.4150/KPMI.2007.14.2.097

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Abstract PDF: The magnetic alloys of Cu-Fe (Cu_50Fe_50,;Cu_80Fe_20;and;Cu_90Fe_10) were prepared by a mechanical alloying method and their structural and magnetic behaviors were examined by X-ray diffraction and Mossbauer spectra. The magnetization curves did not distinctly show the saturation at 70 kOe for the concentrated alloys of Cu_80Fe_20;and;Cu_90Fe_10. The Mossbauer spectrum of Cu_80Fe_20 at room temperature shows one Lorentzian line of the paramagnetic phase, whereas the Mossbauer spectrum of Cu_90Fe_10 consists of sextet Lorentzian line at room temperature and a centered doublet line. The Mossbauer spectra of Cu_90Fe_10 measured in the temperature ranges from 13 to 295 K, implies that Cu_90Fe_10 to consists of two magnetic phases. One superimposed sextet corresponds to the ferromagnetic iron in Cu and the other one indicates the superparamagnetic iron rich phase.

A study on the Particulate Properties of Ti-Ni alloy Nanopowders Prepared by Levitational Gas Condensation Method: B.S. Han, Y.R. Uhm, M.K. Lee, G.M. Kim, C.K. Rhee; J Korean Powder Metall Inst. 2006;13(6):396-400.; DOI: https://doi.org/10.4150/KPMI.2006.13.6.396

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Abstract PDF: The Ti-Ni alloy nanopowders were synthesized by a levitational gas condensation (LGC) by using a micron powder feeding system and their particulate properties were investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) method. The starting Ti and Ni micron powders 150µm were incorporated into the micron powder feeding system. An ingot type of the Ti-Ni ahoy was used as a seed material for the levitation and evaporation reactions. The collected powders were finally passivated by oxidation. The x-ray diffraction experiments have shown that the synthesized powders were completely alloyed with Ti and Ni and comprised of two different cubic and monoclinic crystalline phases. The TEM results showed that the produced powders were very fine and uniform with a spherical particle size of 18 to 32nm. The typical thickness of a passivated oxide layer on the particle surface was about 2 to 3 nm. The specific surface area of the Ti-Ni alloy nanopowders was 60m2/g based on BET method.

Room-temperature Ferromagnetism in Fe-doped Reduced TiO_2-δ: H.M. Lee, C.S. Kim, Y.R. Uhm, C.K. Rhee; J Korean Powder Metall Inst. 2006;13(6):401-407.; DOI: https://doi.org/10.4150/KPMI.2006.13.6.401

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Abstract PDF: Effects of oxygen deficiency on the room temperature ferromagnetism in Fe-doped reduced TiO_2 have been investigated by comparing the air-annealed Ti_0.97Fe_0.03O_2 compound with secondly post-annealed one in vacuum ambience. The air-annealed sample showed a paramagnetic behavior at room temperature. However, when the sample was further annealed in vacuum, a strongly enhanced ferromagnetic behavior was observed at same temperature. M"ossbauer spectra of air-annealed sample at 295K showed a single doublet of Fe3+

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