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나노인덴테이션을 이용한 MLCC용 BaTiO<sub>3</sub> 세라믹스의 기계적 물성평가
류성수,김성원,김형준,김형태,Ryu, Sung-Soo,Kim, Seong-Won,Kim, Hyeong-Jun,Kim, Hyung-Tae 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.1
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 $1260^{\circ}C$. 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.
AlN 분말의 고에너지 밀링에 따른 소결체의 절연 특성
류성수,이성민,Ryu, Sung-Soo,Lee, Sung-Min 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.6
Aluminum nitride (AlN) powder specimens are treated by high-energy bead milling and then sintered at various temperatures. Depending on the solvent and milling time, the oxygen content in the AlN powder varies significantly. When isopropyl alcohol is used, the oxygen content increases with the milling time. In contrast, hexane is very effective at suppressing the oxygen content increase in the AlN powder, although severe particle sedimentation after the milling process is observed in the AlN slurry. With an increase in the milling time, the primary particle size remains nearly constant, but the particle agglomeration is reduced. After spark plasma sintering at $1400^{\circ}C$, the second crystalline phase changes to compounds containing more $Al_2O_3$ when the AlN raw material with an increased milling time is used. When the sintering temperature is decreased from $1750^{\circ}C$ to $1400^{\circ}C$, the DC resistivity increases by approximately two orders of magnitude, which implies that controlling the sintering temperature is a very effective way to improve the DC resistivity of AlN ceramics.
고에너지 볼밀링에 의해 제조된 Gd<sub>2</sub>O<sub>3</sub>-doped CeO<sub>2</sub> 나노분말의 소결 거동에 관한 연구
류성수,김형태,Ryu, Sung-Soo,Kim, Hyung-Tae 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.4
$Gd_2O_3$-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 $1200^{\circ}C$ of nano-sized GDC powder mixture led to GDC solid-solution. The enhanced densification over 96% of relative density was obtained after sintering at $1300^{\circ}C$ 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.
류운영,허유,허성수,Ryu, woon-Yeong,Huh, You,Huh, Sung-Soo 한국섬유공학회 1981 한국섬유공학회지 Vol.18 No.3
This study was carried out in order to investigate the compressional deformation of cut-pile carpet. The results are summarized as follows; 1) Pile density being constant, as pile height increases compressional load decreases and pile height being constant, compressional load increases as pile density increases. 2) There is non-linear relationship between the compressional deformation and the load. Linear relationship can be obtained by In-ln plotting of the ratio of load and time. 3) The equation for the relation between the load and pile height is 4) Though the time dependence of compressional deformation exists, relaxation time is very short.
열전지 음극재용 Li-Si 원료의 성형성에 미치는 입자크기와 바인더첨가 효과
류성수,김희식,김성원,김형태,정해원,이성민,Ryu, Sung-Soo,Kim, Hui-Sik,Kim, Seongwon,Kim, Hyung-Tae,Cheong, Hae-Won,Lee, Sung-Min 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.5
The effects of particle size of Li-Si alloy and LiCl-KCl addition as a binder phase for raw material of anode were investigated on the formability of the thermal battery anode. The formability was evaluated with respect to filling density, tap density, compaction density, spring-back and compressive strength. With increasing particle size of Li-Si alloy powder, densities increased while spring-back and compressive strength decreased. Since the small spring-back is beneficial to avoiding breakage of pressed compacts, larger particles might be more suitable for anode forming. The increasing amount of LiCl-KCl binder phase contributed to reducing spring-back, improving the formability of anode powder too. The control of particle size also seems to be helpful to get double pressed pellets, which consisted of two layer of anode and electrolyte.
고에너지 볼밀링된 BaCO<sub>3</sub>와 TiO<sub>2</sub> 혼합분말의 고상반응에 의한 나노결정 BaTiO<sub>3</sub> 분말 합성
류성수,Ryu, Sung-Soo 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.4
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 $800^{\circ}C$. High tetragonal $BaTiO_3$ powder with a tetragonality(=c/a) of 1.009 and a specific surface area of $7.6m^2/g$ was acquired after heat-treatment at $950^{\circ}C$ for 2 h. High energy ball milling was effective in decreasing the reaction temperature and increasing the tetragonality.
열전지 양극용 FeS<sub>2</sub> 분말의 성형성에 미치는 Li<sub>2</sub>O 첨가 및 열처리의 효과
류성수,이원진,김성원,정해원,조성백,강승호,이성민,Ryu, Sung-Soo,Lee, Won-Jin,Kim, Seongwon,Cheong, Hae-Won,Cho, Sung-Baek,Kang, Seung-Ho,Lee, Sung-Min 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.3
$FeS_2$ has been widely used for cathode materials in thermal battery because of its high stability and current capability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical performance and formability of $FeS_2$ cathode powder. In this study, the effects of the addition of $Li_2O$ in LiCl-KCl binder on the formability of $FeS_2$ powder compact were investigated. With the increasing amount of $Li_2O$ addition to LiCl-KCl binder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treated above $350^{\circ}C$. The heat-treatment resulted in promoting the coating coverage of $FeS_2$ particles by the salts as $Li_2O$ was added. The observed coating as $Li_2O$ addition might be attributed to the enhanced wettability of the salt rather than its reduced melting temperature. The high strength of compacts by the $Li_2O$ addition and pre-heat-treatment could improve the formability of $FeS_2$ raw materials.
$Al(OH)_3$ 함유(含有) 인조대리석폐기물(人造大理石廢棄物)로부터 제조(製造)된 알루미나 분말(粉末)의 특성(特性) 및 소결거동(燒結擧動) 연구(硏究)
류성수,서성규,김형태,김형준,박준규,양재규,Ryu, Sung-Soo,Seo, Sung-Gyu,Kim, Hyung-Tae,Kim, Hyeong-Jun,Park, Jun-Gyu,Yang, Jae-Gyu 한국자원리싸이클링학회 2009 資源 리싸이클링 Vol.18 No.2
Alumina powder was prepared from heat-treatment of artificial marble waste fine aggregate containing $Al(OH)_3$ for the purpose of the feasibility of its recycling. Artificial marble waste was heat-treated between $500^{\circ}C$ and $1000^{\circ}C$ and XRD, BET surface area, BJH pore size distribution and adsorption of As were analyzed for heat-treated powder. It was found that the adsorption efficiency of As was significantly affected by phase composition of alumina powder rather than its physical characteristic. Heat-treated powder compact was sintered to produce the pellet. Alumina pellet with porosity more than 60% could be obtained after sintering below $1200^{\circ}C$ and also the addition of glass powder as a sintering aid had a positive effect on lowering sintering temperature, led to the high porosity near 60% and adsorption of As over 60% even at $900^{\circ}C$. 본 연구에서는 수산화 알루미늄이 다량 포함되어 있는 인조대리석 폐기물을 폐광산지역의 지하수 및 지표수 등에서 검출되는 유해중금속 제거용으로 재활용 가능성을 조사하고자 하였다. 이를 위해 폐기물을 $550^{\circ}C$에서 $1000^{\circ}C$ 온도범위에서 열처리하여 알루미나 분말을 추출하였으며, 이렇게 얻어진 열처리분말에 대해 온도에 따른 상변화를 XRD를 통해 분석하고, 비표면적 측정, SEM 분석 등을 통해 분말의 특성을 조사하고, 중금속인 비소의 흡착특성을 조사하였다 그 결과, 열처리된 알루미나 산화물 분말이 중금속 처리에 효과가 있음을 확인할 수 있었으며, 열처리분말의 구성성분에 영향을 받는다는 것을 알 수 있었다. 또한, 열처리 분말 성형체를 소결한 결과, $1200^{\circ}C$ 이하에서 60% 이상의 높은 기공률을 가진 펠렛을 제조할 수 있었으며, 소결조제인 glass 분말의 첨가에 의해 $900^{\circ}C$의 낮은 소결온도에서도 기공률을 유지하면서 비교적 높은 비소흡착률을 가지는 시편을 제조할 수 있었다.
나노크기의 ZrO<sub>2</sub>와 Graphite 분말 혼합체의 열탄소환원법에 의한 고분산 초미립 ZrC 분말의 합성
이화준,류성수,Lee, Wha-Jun,Ryu, Sung-Soo 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.2
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 $1500^{\circ}C$ for 2 h under vacuum, ultra-fine ZrC powder agglomerates (average size, $4.2{\mu}m$) 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.