Journal of Powder Materials

Effect of Particle Size on Compactibility of Water-atomized Pure Iron Powder: Dong-Jun Lee, Eun-Yoo Yoon, Ha-Neul Kim, Hee-Soo Kang, Eon-Sik Lee, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2011;18(3):221-225.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.221

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In the current study, the effects of particle size on compaction behavior of water-atomized pure iron powders are investigated. The iron powders are assorted into three groups depending on the particle size; 20-45 µM, 75-106 µM, and 150-180 µM for the compaction experiments. The powder compaction procedures are processed with pressure of 200, 400, 600, and 800 MPa in a cylindrical die. After the compaction stage, the group having 150-180 µM of particle size distribution shows the best densification behavior and reaches the highest green density. The reason for these results can be explained by the largest average grain size in the largest particle group, due to the low plastic deformation resistance in large grain sized materials.

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Preparation of high-purity reduced iron powder by Höganäs process from ultra-pure magnetite concentrate
Jin-tian Wu, Bin Xu, Zhong-lin Dong, Yu-juan Zhou, Liang-ping Xu, Guang-hui Li, Tao Jiang
Journal of Central South University.2023; 30(9): 3006. CrossRef
Hydrogen Reduction Behavior of Oxide Scale in Water-atomized Iron Powder
Hea-Min Shin, Kyeong-Ho Baik
Journal of Korean Powder Metallurgy Institute.2014; 21(6): 422. CrossRef
Quantitative Analysis of Roughness of Powder Surface Using Three-Dimensional Laser Profiler and its Effect on Green Strength of Powder Compacts
Dong-Jun Lee, Eun-Yoo Yoon, Ha-Neul Kim, Hee-Soo Kang, Eon-Sik Lee, Hyoung-Seop Kim
Journal of Korean Powder Metallurgy Institute.2011; 18(5): 406. CrossRef

Manufacturing and Properties of Low Vacuum Plasma Sprayed W-Carbide Hybrid Coating Layer: Jin-Hyeon Cho, Young-Min Jin, Jee-Hoon Ahn, Kee-Ahn Lee; J Korean Powder Metall Inst. 2011;18(3):226-237.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.226

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Abstract PDF: W-ZrC and W-HfC composite powders were fabricated by the Plasma Alloying & Spheroidization (PAS) method and the powders were sprayed into hybrid coating layers by using Low Vacuum Plasma Spray (LVPS) process, respectively. Microstructure, mechanical properties, and ablation characteristics of the fabricated coating layers were investigated. The LVPS process led to successful production of W-Carbide hybrid coatings, approximately 400 µM or above in thickness. As the substrate preheating temperature increased from 870°C to 917°C, the hardness of the W-ZrC coating layer increased due to decreased porosity. Vickers hardness showed higher value (about 108.4 HV) in W-ZrC hybrid coating material compared to that of W-HfC while adhesive strength was found to be similar in both coating layers. The plasma torch test revealed good ablation resistance of the W-Carbide hybrid coating layers. The relatively high performance W-ZrC coating layer at the elevated temperature is thought to be attributed to both the strengthening effect of ZrC particle remained in the layer and the formation of ZrO2 phase with high temperature stability.

Synthesis of Al/AlN Composites by Mechanical Alloying and the Effect of PCA on Their Properties: Seok-Hyeoun Kim, Yong-Jin Kim, Jung-Ho Ahn; J Korean Powder Metall Inst. 2011;18(3):238-243.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.238

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Abstract PDF: Al/AlN composites were synthesized by mechanical alloying using process control agents(PCAs). Three different PCAs which contain N element, were examined to see the effectiveness of ball-milling and the nitridation during sintering. Among examined PCAs, C_8H_6N_4O_5 was the most effective to facilitate ball-milling and to form nitrides during a subsequent sintering. By a proper control of ball-milling and sintering, we could obtained surface-hardened Al-based composites.

Preparation of the Nano Cobalt Powder by Wet Chemical Reduction Method: Hyun-Seon Hong, Young-Dae Ko, Lee-Seung Kang, Geon-Hong Kim, Hang-Chul Jung; J Korean Powder Metall Inst. 2011;18(3):244-249.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.244

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Spherical nanosized cobalt powder with an average size of 150-400 nm was successfully prepared at room temperature from cobalt sulfate heptahydrate (CoSO_4cdot7H_2O). Wet chemical reduction method was adopted to synthesize nano cobalt powder and hypophosphorous acid (H_3PO_2) was used as reduction agent. Both the HCP and the FCC Co phase were developed while CoSO_4cdot7H_2O concentration ranged from 0.7 M to 1.1 M. Secondary phase such as Co(OH)_2 and CO_3O_4 were also observed. Peaks for the crystalline Co phase having HCP and FCC structure crystallized as increasing the concentration of H_3PO_2, indicating that the amount of reduction agent was enough to reduce Co(OH)_2. Consequently, a homogeneous Co phase could be developed without second phase when the H_3PO_2/CoSO_4cdot7H_2O ratio exceeded 7.

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First-principles calculations to investigate electrochemical performance, storage mechanism and magnetocaloric effect of LiFeBO3 for lithium-ion batteries and magnetic refrigerants
Othmane Mennaoui, Rachid Masrour, Ling Xu, El Kebir Hlil
Ionics.2024;[Epub] CrossRef
Spark plasma sintering of WC–Co tool materials prepared with emphasis on WC core–Co shell structure development
Sungkyu Lee, Hyun Seon Hong, Hyo-Seob Kim, Soon-Jik Hong, Jin-Ho Yoon
International Journal of Refractory Metals and Hard Materials.2015; 53: 41. CrossRef
Coating of Cobalt Over Tungsten Carbide Powder by Wet Chemical Reduction Method
Hyun-Seon Hong, Jin-Ho Yoon
Journal of Korean Powder Metallurgy Institute.2014; 21(2): 93. CrossRef
Optimization of Wet Reduction Processing for Nanosized Cobalt Powder
Hyun-Seon Hong, Hang-Chul Jung, Geon-Hong Kim, Lee-Seung Kang, Han-Gil Suk
Journal of Korean Powder Metallurgy Institute.2013; 20(3): 191. CrossRef
Synthesis and Characterization of CoFe2O4/SiO2using Cobalt Precursors from Recycling Waste Cemented Carbide
Ri Yu, Jae-Hwan Pee, Yoo-Jin Kim
Journal of the Korean Ceramic Society.2011; 48(5): 454. CrossRef
Preparation of Spherical Cobalt Fine Powders by New Liquid Reduction Method
Dae Weon Kim, Ji-Hoon Kim, Yo-Han Choi, Hee Lack Choi, Jin-Ho Yoon
journal of Korean Powder Metallurgy Institute.1970; 22(4): 260. CrossRef

Oxygen-Response Ability of Hydrogen-Reduced Nanocrystalline Cerium Oxide: Dong-Won Lee; J Korean Powder Metall Inst. 2011;18(3):250-255.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.250

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Abstract PDF: The potential application of ultrafine cerium oxide (ceria, CeO_2) as an oxygen gas sensor has been investigated. Ceria was synthesized by a thermochemical process: first, a precursor powder was prepared by spray drying cerium-nitrate solution. Heat treatment in air was then performed to evaporate the volatile components in the precursor, thereby forming nanostructured CeO_2 having a size of approximately 20 nm and specific surface area of 100 m2/g. After sintering with loosely compacted samples, hydrogen-reduction heat treatment was performed at 773K to increase the degree of non-stoichiometry, x, in CeO_2-x. In this manner, the electrical conductivity and oxygen-response ability could be enhanced by increasing the number of oxygen vacancies. After the hydrogen reduction at 773K, CeO_1.5 was obtained with nearly the same initial crystalline size and surface. The response time t_90 measured at room temperature was extremely short at 4 s as compared to 14 s for normally sintered CeO_2. We believe that this hydrogen-reduced ceria can perform capably as a high-performance oxygen sensor with good response abilities even at room temperature.

Effects of Ball Milling Condition on Sintering of Cu, Zn, Sn and Se Mixed Powders: Jong-Heon Ahn, Woon-Hwa Jung, Yun-Jung Jang, Seong-Heon Lee, Kyoo-Ho Kim; J Korean Powder Metall Inst. 2011;18(3):256-261.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.256

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Abstract PDF: In order to make a Cu_2ZnSnSe_4 (CZTSe) sputtering target sintered for solar cell application, synthesis of CZTSe compound by solid state reaction of Cu, Zn, Sn and Se mixed powders and effects of ball milling condition on sinterability such as ball size, combination of ball size, ball milling time and sintering temperature, was investigated. As a result of this research, sintering at 500°C after ball milling using mixed balls of 1 mm and 3 mm for 72 hours was the optimum condition to synthesis near stoichiometric composition of Cu_2ZnSnSe_4 and to prepare sintered pellet with high density relatively.

The Characteristic Changes of Sintered WC-10Co Fabricated by PIM Method with Different Carbon Content: Sang-Dae Kang, Dong-Wook Park, Young-Sam Kwon, Kwon-Koo Cho, In-Shup Ahn; J Korean Powder Metall Inst. 2011;18(3):262-268.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.262

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Abstract PDF: In order to investigate the microstructure and mechanical properties of WC-10 wt% Co insert tool alloy fabricated by PIM (Powder Injection Molding) process, the feedstock of WC-10 wt% and wax used as a kind of binder were mixed together by two blade mixer. After injection molding, the debinding process was carried out by two-steps. First, solvent extraction, in which the binder was eliminated by putting the specimen into normal hexane for 24 hrs at 60°C, and subsequently thermal debinding which was conducted at 260°C and 480°C for 6 hrs in the mixed gas of H_2/N_2, respectively. Meantime, in order to compensate the decarburization due to hydrogen, 1.2~1.8% of carbon was added to ensure the integrity of the phase. Finally, the specimens were sintered in vacuum under different temperatures, and the relative density of 99.8% and hardness of 2100 Hv can be achieved when sintered at 1380°C, even the TRS is lower than the conventional sintering process.

The Synthesis of Hydrophobic Silica Aerogel in the Macroporous Ceramic Structure by Ambient Drying Process: Sun-Wook Hong, In-Hyuck Song, Young-Jo Park, Hui-Suk Yun, Yoo-Dong Hahn, Ki-Young Hwang, Young-Woo Rhee; J Korean Powder Metall Inst. 2011;18(3):269-276.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.269

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Abstract PDF: The synthesis behavior of nanoporous silica aerogel in the macroporous ceramic structure was observed using TEOS as a source material and glycerol as a dry control chemical additive (DCCA). Silica aerogel in the macroporous ceramic structure was synthesized via sono-gel process using hexamethyldiazane (HMDS) as a modification agent and n-hexane as a main solvent. The wet gel with a modified surface was dried at 105°C under ambient pressure. The addition of glycerol appears to give the wet gel a more homogeneous microstructure. However, glycerol also retarded the rate of surface modification and solvent exchange. Silica aerogel completely filled the macroporous ceramic structure without defect in the condition of surface modification (20% HMDS/nhexane at 36hr).

Synthesis of LiCoO₂ Powders using Recycled Cobalt Precursors from Waste WC-Co Hard Metal: Hee-Seung Yang, Jae-Hwan Pee, Yoo-Jin Kim; J Korean Powder Metall Inst. 2011;18(3):277-282.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.277

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[ LiCoO_2 ] a cathode material for lithium rechargeable batteries, was prepared using recycled Co_3O_4. First, the cobalt hydroxide powders were separated from waste WC-Co hard metal with acid-base chemical treatment, and then the impurities were eliminated by centrifuge method. Subsequently, Co_3O_4 powders were prepared by thermal treatment of resulting Co(OH)_2. By adding a certain amount of Li_2CO_3 and LiOHcdotH_2O, the LiCoO_2 was obtained by sintering for 10 h in air at 800°C. The synthesized LiCoO_2 particles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis.

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Fabrication of Flake-like LiCoO2Nanopowders using Electrospinning
Bon-Ryul Koo, Geon-Hyoung An, Hyo-Jin Ahn
Journal of Korean Powder Metallurgy Institute.2014; 21(2): 108. CrossRef

Effect of MgO and NH₄OH on Formation of 5Mg(OH)₂·MgSO₄·3H₂O Whiskers: Ri Yu, Jae-Hwan Pee, Hyung-Tae Kim, Kyung-Ja Kim, Young-Woong Kim, Woong Kim, Yoo-Jin Kim; J Korean Powder Metall Inst. 2011;18(3):283-289.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.283

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Magnesium hydroxide sulfate hydrate whiskers (5Mg(OH)_2cdotMgSO_4cdot3H_2O, abbreviated 513 MHSH) were prepared using hydrothermal reaction with magnesium oxide (MgO) and magnesium sulfate (MgSO_4cdot7H_2O) as the starting materials. The effects of the molar ratio of MgSO_4/MgO and amount of NH_4OH were studied. As a result, 513 MHSH whiskers co-existed with hexagonal plate Mg(OH)_2 at low concentration of SO_42-. The molar ratio of MgSO_4cdot7H_2O/MgO was 7:1, uniform 513 MHSH whiskers were formed without impurity such as Mg(OH)_2. Appropriate amount of NH_4OH has affected to formation of high quality MHSH. Their morphologies and structures were determined by powder X-ray diffraction (XRD) scanning electron microscopy (SEM) and thermo-gravimetric analyzer (TGA).

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Effect of sulfate ion on synthesis of 5 Mg(OH)2·MgSO4·3H2O whiskers using non-hydrothermal method with acid catalyst
Areum Choi, Nuri Oh, YooJin Kim
Journal of the Korean Ceramic Society.2022; 59(2): 224. CrossRef
Effect of H₂SO₄ and Reaction Time on Synthesis of 5Mg(OH)₂∙MgSO₄∙3H₂O Whiskers using Hydrothermal Reaction
Areum Choi, Nuri Oh, YooJin Kim
Journal of Korean Powder Metallurgy Institute.2020; 27(5): 401. CrossRef
Study of Fabrication and Improvement of Mechanical Properties of Mg-based Inorganic Fiber using Reflux Process and Silica Coating
Ri Yu, YooJin Kim
Journal of Korean Powder Metallurgy Institute.2019; 26(3): 195. CrossRef
Effect of MgSO4/MgO on the Synthesis of 5Mg(OH)2·MgSO4·3H2O Whiskers using One-step Ambient Pressure
Ri Yu, Jae-Hwan Pee, Hyung Tae Kim, YooJin Kim
Journal of the Korean Ceramic Society.2013; 50(3): 201. CrossRef

Characteristics of Stainless Steel Composites with Nano-sized TiCxNy: Tae-Ho Ban, Sung-Bum Park, Soo-Jeong Jo, Dong-Won Lee, Farkhod R. Turaev, Yong-Il Park, Sung-Jin Kim; J Korean Powder Metall Inst. 2011;18(3):290-296.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.290

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Abstract PDF: Titanium carbonitride is more perspective materials compared to titanium carbide. It can be used in tool industry and special products because of its higher strength, abrasive wear-resistance and especially its strong chemical stability at high temperatures. We produced STS+TiCxNy composite by the spark plasma sintering for higher strength and studied the characteristics. The planar and cross-sectional microstructures of the specimens were observed by scanning electron microscopy. Characterizations of the carbon and nitride phases on the surface of composite were carried out using an X-ray diffractometer. During annealing TiCxNy particles diffusion into STS 430 was observed. After annealing, sintering isolations between particles were formed. It causes decreasing of mechanical strength. In addition when annealing temperature was increased hardness increased. Heterogeneous distribution of alloying elements particles was observed. After annealing composites, highest value of hardness was 738.1 MHV.

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

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