Journal of Powder Materials

Volume 20(6); December 2013

Effect of Passivation on the Sintering Behavior of Submicron Nickel Powder Compacts for MLCC Application: Gi-Young Jo, Kwi-Jong Lee, Suk-Joong L. Kang; J Powder Mater. 2013;20(6):405-410.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.405

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During sintering of Ni-electrode multi-layer ceramic capacitors (MLCCs), the Ni electrode often becomes discontinuous because of its lower sintering temperature relative to that of BaTiO_3. In an attempt to retard the sintering of Ni, we introduced passivation of the Ni powder. To find the optimal passivation conditions, a thermogravimetric analysis (TGA) was conducted in air. After passivation at 250°C for 11 h in air, a nickel oxide shell with a thickness of 4-5 nm was formed on nickel nanoparticles of 180 nm size. As anticipated, densification of the compacts of the passivated Ni/NiO core-shell powder was retarded: the starting temperature of densification increased from sim400°C to sim600°C in a 97N_2-3H_2 (vol %) atmosphere. Grain growth was also retarded during sintering at temperatures of 750 and 1000°C. When the sintering atmosphere was changed from wet 99.93N_2-0.07H_2 to wet 99.98N_2-0.02H_2, the average grain size decreased at the same sintering temperature. The conductivity of the passivated powder sample sintered at 1150°C for 8 h in wet 99.93N_2-0.07H_2 was measured to be 3.9times104S/cm, which is comparable with that, 4.6times104S/cm, of the Ni powder compact without passivation. These results demonstrate that passivation of Ni is a viable means of retarding sintering of a Ni electrode and hence improving its continuity in the fabrication of BaTiO_3-based multi-layer ceramic capacitors.

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In-situ preparation of Ni@ZrO2 nanocapsules powder by DC arc plasma for internal electrode of MLCC
Xi-Yang Li, Xing-Hao Qu, Dong Liu, Guang-Yun Zhu, Xing-Long Dong, Youngguan Jung
Vacuum.2024; 224: 113130. CrossRef
Effect of Sn addition on the low temperature shrinkage of Ni nanoparticles
Jongwon Lee, Hyung-Ho Kim, Hyunwoong Na, Jeongryeol Kim, Seong-Hyeon Hong
Ceramics International.2024; 50(4): 6793. CrossRef
Research Trends on the Influence of Oxygen Vacancies in Post BaTiO3 (BT) Ceramics for Next-Generation MLCCs
Intae Seo, Ka-Young Lee, Cheol-Min Oh, Hyoung-Won Kang
Ceramist.2023; 26(2): 172. CrossRef
Coating Ni particles to preserve their conductivity during sintering in oxidizing atmospheres
Damoon Sohrabi Baba Heidary, Clive A. Randall
Chemical Engineering Journal.2016; 304: 1009. CrossRef
Redesigning Multilayer Ceramic Capacitors by Preservation of Electrode Conductivity and Localized Doping
Damoon Sohrabi Baba Heidary, Clive A. Randall
ACS Applied Materials & Interfaces.2016; 8(45): 31449. CrossRef
Study on the behavior of atomic layer deposition coatings on a nickel substrate at high temperature
Damoon Sohrabi Baba Heidary, Clive A Randall
Nanotechnology.2016; 27(24): 245701. CrossRef

Synthesis of Nickel and Copper Nanopowders by Plasma Arc Evaporation: Young-Sang Cho, Jong Woo Moon, Kook Chae Chung, Jung-Goo Lee; J Powder Mater. 2013;20(6):411-424.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.411

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In this study, the synthesis of nickel nanoparticles and copper nanospheres for the potential applications of MLCC electrode materials has been studied by plasma arc evaporation method. The change in the broad distribution of the size of nickel and copper nanopowders is successfully controlled by manifesting proper mixture of gas ambiance for plasma generation in the size range of 20 to 200 nm in diameter. The factors affecting the mean diameter of the nanopowder was studied by changing the composition of reactive gases, indicating that nitrogen enhances the formation of larger particles compared to hydrogen gas. The morphologies and particle sizes of the metal nanoparticles were observed by SEM, and ultrathin oxide layers on the powder surface generated during passivation step have been confirmed using TEM. The metallic FCC structure of the nanoparticles was confirmed using powder X-ray diffraction method.

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Tribological properties and tribomechanism of nickel nanoparticles in-situ synthesized in rapeseed oil
Wenya Xu, Guangbin Yang, Shengmao Zhang, Jun Xu, Yujuan Zhang, Tianhua Sun, Ningning Song, Laigui Yu, Pingyu Zhang
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Arc Discharge Synthesis of Chitosan‐Mediated Copper Nanoparticles for Heterogeneous Catalysis in 4‐Nitrophenol Degradation
Noor Azfarena Ahmad, Mohammad Taghi Hajibeigy, Mohsen Nabi Poor, Aras Kartouzian, Hassan Moeini, Kamyar Shameli
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Functional metal powders: Design, properties, applications, and prospects
Xin Wang, Haitao Yang, Xiaohua Yu, Chaoquan Hu, Jiacheng Hu, Rongxing Li, Yingzhi Zhang
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Facile synthesis of Cu and CuO nanoparticles from copper scrap using plasma arc discharge method and evaluation of antibacterial activity
S. B. Tharchanaa, K. Priyanka, K. Preethi, G. Shanmugavelayutham
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Fabrication of Hollow or Macroporous Silica Particles by Spray Drying of Colloidal Dispersion
Young-Sang Cho
Journal of Dispersion Science and Technology.2016; 37(1): 23. CrossRef
Fabrication Of Colloidal Clusters Decorated With Dye Molecules For Potential Application As Photonic Molecules
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Effect of Sintering Temperature on the Microstructure and Mechanical Properties of Solid Oxide Fuel Cell Anode Fabricated by Spark Plasma Sintering: Byung Ju Song, Ka Ram Kim, Hye Sung Kim; J Powder Mater. 2013;20(6):425-431.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.425

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Abstract PDF: Microstructural and mechanical properties of Ni-YSZ fabricated using SPS processing have been investigated at various sintering temperatures. Our study shows samples to be applied as a SOFC anode have the proper porosity of 40% and high hardness when processed at 1100°C. These results are comparable to the values obtained at 100-200°C higher sintering temperature reported by others. This result is important because when the fabrication processes are performed above 1100°C, the mechanical property starts to decrease drastically. This is caused by the fast grain coarsening at the higher temperature, which initiates a mismatch between thermal expansion coefficients of Ni and YSZ and induces cracks as well.

The Oxidation Behavior of Sintered STS 316L at High-Temperature in the Air: Hye Seong Kim, Jong Pil Lee, Dong Kyu Park, In Shup Ahn; J Powder Mater. 2013;20(6):432-438.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.432

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In this study, analysis on the oxidation behavior was conducted by a series of high-temperature oxidation tests at both 800°C, 900°C and 1000 in the air with sintered STS 316L. The weight gain of each oxidized specimen was measured, the oxidized surface morphologies and composition of oxidation layer were analyzed with Scanning Electron Microscope-Energy Dispersive x-ray Spectroscopy (SEM-EDS), finally, the phase change and composition of the oxidized specimen were shown by X-Ray Diffraction (XRD). As a result, the weight gain increased sharply at 1000°C when oxidation test was conducted for 210 hours. Also, a plentiful of pores were observed in the surface oxidation layers at 900°C for 210 hours. In addition, the following conclusions on oxidation behavior of sintered STS 316L can be obtained: Cr_2O_3 can be formed on pores by influxing oxygen through open-pores, (Fe_0.6Cr_0.4)_2O_3 can be generated on the inner oxidation layer, and Fe_2O_3 was on the outer oxidation layer. Also, NiFe_2O_4 could be precipitated if the oxidation time was kept longer.

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Effect of laser remelting on the surface characteristics of 316L stainless steel fabricated via directed energy deposition
Seung Yeong Cho, Gwang Yong Shin, Do Sik Shim
Journal of Materials Research and Technology.2021; 15: 5814. CrossRef
The Effect of Oxide Compound on Electrical Resistivity and Oxidation Stability in High-temperature for Ferritic P/M Stainless Steel
Jin-Woo Park, Byung-Hyun Ko, Woo-young Jung, Dong-Kyu Park, In-Shup Ahn
Journal of Korean Powder Metallurgy Institute.2016; 23(3): 240. CrossRef
The Effects of Composition and Microstructure Variation on the Oxidation Characteristics of Stainless Steels Manufactured by Powder Metallurgy Method
Jong-Pil Lee, Ji-Hyun Hong, Dong-Kyu Park, In-Shup Ahn
Journal of Korean Powder Metallurgy Institute.2015; 22(1): 52. CrossRef
The Effect of Oxides Additives on Anti-corrosion Properties of Sintered 316L Stainless Steel
Jong-Pil Lee, Ji-Hyun Hong, Dong-Kyu Park, In-Shup Ahn
journal of Korean Powder Metallurgy Institute.1970; 22(4): 271. CrossRef

The Effect of Binder Content for the Pore Properties of Fe Foam Fabricated by Slurry Coating Process: Jin Ho Choi, Sangsun Yang, Yang-Do Kim, Jung-Yeul Yun; J Powder Mater. 2013;20(6):439-444.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.439

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Fe foam with above 90% porosity and 2 millimeter pore size was successfully fabricated by a slurry coating process. In this study, the binder contents were controlled to produce the Fe foam with different pore size, strut thickness and porosity. Firstly, the slurry was prepared by uniform mixing with Fe powders, distilled water and polyvinyl alcohol(PVA) as initial materials. After slurry coating on the polyurethane(PU) foam the sample was dried at 80°C. The PVA and PU foams were then removed by heating at 700°C for 3 hours. The debinded samples were subsequently sintered at 1250°C with holding time of 3 hours under hydrogen atmosphere. The three dimensional geometries of the obtained Fe foams with open cell structure were investigated using X-ray micro CT(computed tomography) as well as the pore morphology, size and phase.

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Interfacial Bonding and Abrasive Wear Behavior of Iron Matrix Composite Reinforced by Ceramic Particles
Yefei Li, Cong Li, Shuli Tang, Qiaoling Zheng, Juan Wang, Zhibo Zhang, Zhicheng Wang
Materials.2019; 12(22): 3646. CrossRef
A Fatigue Fracture Study on TDCB Aluminum Foam Specimen of Type Mode III Bonded with Adhesive
J.H. Lee, J.U. Cho
Archives of Metallurgy and Materials.2017; 62(2): 1359. CrossRef
Torsion Property of the Structure Bonded Aluminum Foam Due to Impact
G.W. Hwang, J.U. Cho
Archives of Metallurgy and Materials.2017; 62(2): 1353. CrossRef
Experimental Study On Fracture Property Of Double Cantilever Beam Specimen With Aluminum Foam
Y.C. Kim, H.K. Choi, J.U. Cho
Archives of Metallurgy and Materials.2015; 60(2): 1151. CrossRef
Experimental Study On Fracture Property Of Tapered Double Cantilever Beam Specimen With Aluminum Foam
Y.C. Kim, S.S. Kim, J.U. Cho
Archives of Metallurgy and Materials.2015; 60(2): 1459. CrossRef
The Effect of Fe and Fe2O3Powder Mixing Ratios on the Pore Properties of Fe Foam Fabricated by a Slurry Coating Process
Jin Ho Choi, Eun-Mi Jeong, Dahee Park, Sangsun Yang, Yoo-Dong Hahn, Jung-Yeul Yun
Journal of Korean Powder Metallurgy Institute.2014; 21(4): 266. CrossRef

Fabrication and Characteristics of Yttria-stabilized Zirconia (7.5 wt% Y₂O₃-ZrO₂) Coating Deposited via Suspension Plasma Spray: Won-Jun Lee, Chang-Sup Kwon, Seongwon Kim, Yoon-Suk Oh, Hyung-Tae Kim, Dae-Soon Lim; J Powder Mater. 2013;20(6):445-452.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.445

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Yttria-stabilized zirconia (YSZ) coatings are fabricated via suspension plasma spray (SPS) for thermal barrier applications. Three different suspension sets are prepared by using a planetary mill as well as ball mill in order to examine the effect of starting suspension on the phase evolution and the microstructure of SPS prepared coatings. In the case of planetary-milled commercial YSZ powder, a deposited thick coating turns out to have a dense, vertically-cracked microstructure. In addition, a dense YSZ coating with fully developed phase can be obtained via suspension plasma spray with suspension from planetary-milled mixture of Y_2O_3 and ZrO_2.

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Fabrication and Characterization of 7.5 wt% Y2O3-ZrO2Thermal Barrier Coatings Deposited by Suspension Plasma Spray
Won-Jun Lee, Yoon-Suk Oh, Sung-Min Lee, Hyung-Tae Kim, Dae-Soon Lim, Seongwon Kim
Journal of the Korean Ceramic Society.2014; 51(6): 598. CrossRef
Structure and Thermal Conductivity of Thermal Barrier Coatings in Lanthanum/Gadolinium Zirconate System Fabricated via Suspension Plasma Spray
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim
Journal of the Korean institute of surface engineering.2014; 47(6): 316. CrossRef

Preparation of Suspension in La₂O₃-Gd₂O₃-ZrO₂ System via Planetary Mill and Characteristics of (La_1-xGd_x)₂Zr₂O₇ Coatings Fabricated via Suspension Plasma Spray: Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim; J Powder Mater. 2013;20(6):453-459.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.453

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Lanthanum/gadolinium zirconate coatings are deposited via suspension plasma spray with suspensions fabricated by a planetary mill and compared with hot-pressed samples via solid-state reaction. With increase in processing time of the planetary mill, the mean size and BET surface area change rapidly in the case of lanthanum oxide powder. By using suspensions of planetary-milled mixture between lanthanum or gadolinium oxide and nano zirconia, dense thick coatings with fully-developed pyrochlore phases are obtained. The possibilities of these SPS-prepared coatings for TBC application are also discussed.

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Phase Equilibria in the ZrO2–La2O3–Gd2O3 System at 1600°C
E.R. Andrievskaya, O.A. Kornienko, A.I. Bykov, A.V. Sameliuk
Powder Metallurgy and Metal Ceramics.2020; 58(11-12): 714. CrossRef
Characteristics of Bulk and Coating in Gd2−xZr2+xO7+0.5x(x = 0.0, 0.5, 1.0) System for Thermal Barrier Coatings
Sun-Joo Kim, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim
Journal of the Korean Ceramic Society.2016; 53(6): 652. CrossRef
Fabrication and Characterization of Ceramics and Thermal Barrier Coatings of Lanthanum Zirconate with Reduced Rare-earth Contents in the La2O3-ZrO2 System
Chang-Sup Kwon, Sujin Lee, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim
Journal of Korean Powder Metallurgy Institute.2015; 22(6): 413. CrossRef
Structure and Thermal Conductivity of Thermal Barrier Coatings in Lanthanum/Gadolinium Zirconate System Fabricated via Suspension Plasma Spray
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim
Journal of the Korean institute of surface engineering.2014; 47(6): 316. CrossRef

Thermal Durability of 4YSZ Thermal Barrier Coating Deposited by Electron Beam PVD: Chanyoung Park, Younghwan Yang, Seongwon Kim, Sungmin Lee, Hyungtae Kim, Daesoon Lim, Byungkoog Jang, Yoonsuk Oh; J Powder Mater. 2013;20(6):460-466.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.460

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Abstract PDF: 4 mol% Yttria-stabilized zirconia (4YSZ) coatings with 200µm thick are fabricated by Electron Beam Physical Vapor Deposition (EB-PVD) for thermal barrier coating (TBC). 150µm of NiCrAlY based bond coat is prepared by conventional APS (Air Plasma Spray) method on the NiCrCoAl alloy substrate before deposition of top coating. 4 mol% YSZ top coating shows typical tetragonal phase and columnar structure due to vapor phase deposition process. The adhesion strength of coating is measured about 40 MPa. There is no delamination or cracking of coatings after thermal cyclic fatigue and shock test at 850°C.

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 Powder Mater. 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

Preparation of WO₃-TiO₂ Photocatalyst and Evaluation of Its Photo-activity in the Visible Light Range: In-Chul Yeo, In-Cheol Kang; J Powder Mater. 2013;20(6):474-478.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.474

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The most general photocatalyst, TiO_2 and WO_3, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with TiO_2 and WO_3. In the TiO_2-WO_3 composite, WO_3 absorbs visible light creating excited electrons and holes while some of the excited electrons move to TiO_2 and the holes remain in WO_3. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor, retarding the recombination rate of excited electrons and holes. In making a mixture of TiO_2-WO_3 composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of TiO_2(4) and WO_3(6) shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.

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Photocatalytic activity of rutile TiO2 powders coupled with anatase TiO2 nanoparticles using surfactant
Jong Min Byun, Chun Woong Park, Young In Kim, Young Do Kim
journal of Korean Powder Metallurgy Institute.2018; 25(3): 257. CrossRef
Synthesis and Characterization of TiO2/CuS Nanocomposite Fibers as a Visible Light-Driven Photocatalyst
HyeLan An, Leeseung Kang, Hyo-Jin Ahn, Yong-Ho Choa, Chan Gi Lee
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Deaggregation and Ultradispersion of Detonation Nanodiamonds in Polar Solvent Using Physicochemical Treatments: Changkyu Kim, Gyoung-Ja Lee, Changkyu Rhee; J Powder Mater. 2013;20(6):479-486.; DOI: https://doi.org/10.4150/KPMI.2013.20.6.479

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In the present work, physicochemical treatments were introduced for de-aggregation and stable dispersion of detonation nanodiamonds (DND) in polar solvents. The DNDs in water exhibited a particle size of 138 nm and high dispersion stability without particular treatment. However, the DNDs in ethanol were severely aggregated to several micrometers in size and showed poor dispersion stability with time. To break down aggregates of DNDs and enhance the dispersion stability of them in ethanol, mechanical force and chemical surfactant were introduced as functions of zirconia ball size, kind of surfactant and amount of surfactant added. From the analyses of average particle size and Turbiscan results, it was suggested that the size of DNDs in ethanol can be reduced by only mechanical force; however, the DNDs were re-aggregated due to high surface activity. The long-term dispersion stability can be achieved by applying mechanical force to break down the aggregates of DNDs and by preventing re-aggregation of them using proper surfactant.

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