Journal of Powder Materials

Sung-Soo Ryu

9 Articles

Facile Synthesis of Highly Dispersed Ultra-fine ZrC Powders by Carbothermal Reduction Method Using Nanosized ZrO₂ and Nanosized Graphite Powder Mixtures: Wha-Jun Lee, Sung-Soo Ryu; J Powder Mater. 2013;20(2):100-106.; DOI: https://doi.org/10.4150/KPMI.2013.20.2.100

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Abstract PDF: Ultra-fine zirconium carbide (ZrC) powder with nano-sized primary particles was synthesized by the carbothermal reduction method by using nano-sized ZrO_2 and nano-sized graphite powders mixture. The synthesized ZrC powder was well dispersed after simple milling process. After heat-treatment at 1500°C for 2 h under vacuum, ultra-fine ZrC powder agglomerates (average size, 4.2µm) were facilely obtained with rounded particle shape and particle size of ~200 nm. Ultra-fine ZrC powder with an average particle size of 316 nm was obtained after ball milling process in a planetary mill for 30 minutes from the agglomerated ZrC powder.

Thermo-Mechanical Properties of Al₂TiO₅ Ceramics Stabilized with MgO and ZrO₂ Additives: Da-Mi Kim, Hyung-Tae Kim, Hyeong-Jun Kim, Ik-Jin Kim, Seong-Cheol Choi, Yong-Chan Kim, Jung NamKung, Sung-Soo Ryu; J Korean Powder Metall Inst. 2012;19(4):253-258.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.253

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The characteristics of Al_2TiO_5 ceramics were influenced by the additives and the heat treatment that controls the microcrack behavior at grain boundaries. The effect of additives on Al_2TiO_5 ceramics were investigated in terms of mechanical properties and thermal expansion at high temperature. The Al_2TiO_5 were synthesized at 1500°C, 1550°C and 1600°C for 2h by reaction sintering. The formation of Al_2TiO_5 phase was increased by additives that enhanced the volume of the microcrack that can lead to low thermal expansion. The mechanical properties of the stabilized Al_2TiO_5 ceramics were increased remarkably at 1100°C, 1200°C and 1300°C due to the oneset of mechanical healing of grain-bondary microcracks at a high temperature. The amount of microcrack was decreased at lower sintering temperature that causes the increase of mechanical properties at high temperature.

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The influence of different additives on microstructure and mechanical properties of aluminum titanate ceramics
Weiwei Chen, Anze Shui, Qingliang Shan, Jiawei Lian, Cong Wang, Jianqiao Li
Ceramics International.2021; 47(1): 1169. CrossRef

Synthesis of Nanocrystalline BaTiO₃ Powder by the Combination of High Energy Ball Milling of BaCO₃-TiO₂ Mixture and Solid-State Reaction: Sung-Soo Ryu; J Korean Powder Metall Inst. 2012;19(4):310-316.; DOI: https://doi.org/10.4150/KPMI.2012.19.4.310

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Nanocrystalline BaTiO_3 powder could be synthesized by solid-state reaction using the mixture which was prepared by a high energy milling process in a bead mill for BaCO_3 and nanocrystalline TiO_2 powders mixture. Effect of the milling time on the powder characteristic of the synthesized BaTiO_3 powder was investigated. Nanocrystalline BaTiO_3 with a particle size of 50 nm was obtained at 800°C. High tetragonal BaTiO_3 powder with a tetragonality(=c/a) of 1.009 and a specific surface area of 7.6m2/g was acquired after heat-treatment at 950°C for 2 h. High energy ball milling was effective in decreasing the reaction temperature and increasing the tetragonality.

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Enhancement of dielectric properties and microstructure control of BaTiO3 by seed-induced solid-state synthesis
Seong Hyeok Choi, Yoon-Seok Lee, Sang Heun Lee, Kyungki Beak, Seungchan Cho, Ilguk Jo, Yangdo Kim, Kyoung-Seok Moon, Moonhee Choi
Ceramics International.2023; 49(11): 17921. CrossRef
Major factors affecting the dielectric properties and reliability of solid stated reacted BaTiO3powders for capacitor
Seong Hyeok Choi, Yoon-Seok Lee, Hun Kwak, Hyeon Jin Jung, Minkee Kim, Seungchan Cho, Jun Hyeon Yoon, Ji Woo Choi, Min Seong Kim, Ji Hyeon Kim, Ilguk Jo, Yangdo Kim, Moonhee Choi
Journal of Asian Ceramic Societies.2022; 10(4): 713. CrossRef
Preparation of tetragonal barium titanate nanopowders by microwave solid-state synthesis
Haoyu Qian, Guisheng Zhu, Huarui Xu, Xiuyun Zhang, Yunyun Zhao, Dongliang Yan, Xianyong Hong, Yin Han, Zhenxiao Fu, Shiwo Ta, Aibing Yu
Applied Physics A.2020;[Epub] CrossRef
Facile Synthesis of Highly Dispersed Ultra-fine ZrC Powders by Carbothermal Reduction Method Using Nanosized ZrO2and Nanosized Graphite Powder Mixtures
Wha-Jun Lee, Sung-Soo Ryu
Journal of Korean Powder Metallurgy Institute.2013; 20(2): 100. CrossRef

Densification and Microstructure of Ultrafine-sized AlN Powder Prepared by a High Energy Ball Milling Process: Hae-Ryong Park, Young-Do Kim, Sung-Soo Ryu; J Korean Powder Metall Inst. 2012;19(1):25-31.; DOI: https://doi.org/10.4150/KPMI.2012.19.1.025

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Abstract PDF: In this study, a high energy ball milling process was employed in order to improve the densification of direct nitrided AlN powder. The densification behavior and the sintered microstructure of the milled AlN powder were investigated. Mixture of AlN powder doped with 5 wt.% Y_2O_3 as a sintering additive was pulverized and dispersed up to 50 min in a bead mill with very small ZrO_2 beads. Ultrafine AlN powder with a particle size of 600 nm and a specific surface area of 9.54 m2/g was prepared after milling for 50 min. The milled powders were pressureless-sintered at 1700°C-1800°C for 4 h under N_2 atmosphere. This powder showed excellent sinterability leading to full densification after sintering at 1700°C for 4 h. However, the sintered microstructure revealed that the fraction of yitttium aluminate increased with milling time and sintering temperature and the newly-secondary phase of ZrN was observed due to the reaction of AlN with the ZrO_2 impurity.

A Study on Rheological Behavior of Cordierite Honeycomb Extrusion Paste: Yong-Ik Song, Hyung-Tae Kim, Jin-Gu Lee, Won-Jung Yoon, Sung-Soo Ryu; J Korean Powder Metall Inst. 2010;17(1):44-51.; DOI: https://doi.org/10.4150/KPMI.2010.17.1.044

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Abstract PDF: The rheological behavior of a cordierite honeycomb extrusion paste was investigated by measuring torque values in a Brabender plastograph. The extrusion pastes were formulated using binder (methy cellulose, MC), solvent (water), plasticizer (ploy ethylene glycol, PEG) and lubricants (oleic acid, OA). The mixing sequence and optimum organic binder, at least for homogeneous mixed state, can be determined from the rheological point of view. 3%MC-30%H_2O-1.5%PEG-1.0%OA with respect to the cordierite powder was chosen as a binder composition for the extrusion process of cordierite powder.

Feasibility Test for Mechanical Property Characterization of BaTiO₃ Ceramics for MLCC Application Using Nanoindentation: Sung-Soo Ryu, Seong-Won Kim, Hyeong-Jun Kim, Hyung-Tae Kim; J Korean Powder Metall Inst. 2009;16(1):37-42.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.037

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Abstract PDF: In this study, the feasible test for the mechanical property characterization of BaTiO_3 ceramics and multi-layer ceramic capacitor(MLCC) was performed with nanoindentation technique. In case of BaTiO_3 ceramics, hardness and elastic modulus are dependent on the densification of specimen showing the highest hardness and elastic modulus values of 12.3 GPa and 155 GPa, respectively at 1260°C. In case of MLCC chip, hardness of dielectric layer was lower than that of margin region. The nanoindentation method could be useful tool for the measurement of mechanical property within BaTiO_3 dielectric layer of very thin thickness in high capacitance MLCC.

Characterization of Ti(C,N) Solid Solutions in Densified Ti(C,N) and TiC-TiN-Ni Cermet: Seong-Won Kim, Jung-Min Chae, Shin-Hoo Kang, Sung-Soo Ryu, Hyung-Tae Kim; J Korean Powder Metall Inst. 2008;15(6):503-508.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.503

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Abstract PDF: Ti(C,N) solid solutions in hot-pressed Ti(C_xN_1-x) (x=0.0, 0.3, 0.5, 0.7, 1.0) and 40TiC-40TiN-20Ni (in wt.%) cermet were characterized in this study. For hot-pressed Ti(C,N)s, the lattice parameters and hardness values of Ti(C,N) were determined by using XRD (X-Ray Diffraction) and nanoindentation. The properties of hot-pressed Ti(C,N) samples changed linearly with their carbon or nitrogen contents. For the TiC-TiN-Ni cermet, the hardness of the hard phase and binder phase were determined by nanoindentation in conjunction with microstructural observation. The measured hardness values were sim8.7 GPa for the binder phase and sim28.7 GPa for the hard phase, which was close to the hardness of hot-pressed Ti(C_0.7N_0.3).

Measurement of Hardness of Constituent Phases in Ti(C_0.7N_0.3)-NbC-Ni Cermets Using Nanoindentation: Seong-Won Kim, Dae-Min Kim, Shin-Hoo Kang, Sung-Soo Ryu, Hyung-Tae Kim; J Korean Powder Metall Inst. 2008;15(6):482-488.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.482

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Abstract PDF: The indentation technique has been one of the most commonly used techniques for the measurement of the mechanical properties of materials due to its experimental ease and speed. Recently, the scope of indentation has been enlarged down to the nanometer range through the development of instrumentations capable of continuously measuring load and displacement. In addition to testing hardness, the elastic modulus of submicron area could be measured from an indentation load-displacement (P-h) curve. In this study, the hardness values of the constituent phases in Ti(C_0.7N_0.3)-NbC-Ni cermets were evaluated by nanoindentation. SEM observation of the indented surface was indispensable in order to separate the hardness of each constituent phase since the Ti(C_0.7N_0.3)-based cermets have relatively inhomogeneous microstructure. The measured values of hardness using nanoindentation were sim20 GPa for hard phase and sim10 GPa for binder phase. The effect of NbC addition on hardness was not obvious in this work.

Sintering Behavior of Nano-sized Gd₂O₃-doped CeO₂ Powder Prepared by A High Energy Ball Milling: Sung-Soo Ryu, Hyung-Tae Kim; J Korean Powder Metall Inst. 2008;15(4):302-307.; DOI: https://doi.org/10.4150/KPMI.2008.15.4.302

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Gd_2O_3-doped CeO_2(GDC) solid solutions have been considered as a promising materials for electrolytes in intermediate-temperature solid oxide fuel cells. In this study, the nano-sized GDC powder with average panicle size of 69nm was prepared by a high energy ball milling process and its sintering behavior was investigated. Heat-treatment at 1200°C of nano-sized GDC powder mixture led to GDC solid-solution. The enhanced densification over 96% of relative density was obtained after sintering at 1300°C for 2h. It was found that the sinterability of GDC powder could be significantly improved by the introduction of a high energy ball milling process.

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Synthesis of Nanocrystalline BaTiO3Powder by the Combination of High Energy Ball Milling of BaCO3-TiO2Mixture and Solid-State Reaction
Sung-Soo Ryu
Journal of Korean Powder Metallurgy Institute.2012; 19(4): 310. CrossRef

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