Journal of Powder Materials

Phase Formation and Thermo-physical Properties of Lanthanum/Gadolinium Zirconate with Reduced Rare-earth Contents for Thermal Barrier Coatings: Sujin Lee, Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Sahn Nahm, Seongwon Kim; J Korean Powder Metall Inst. 2015;22(6):420-425. Published online December 1, 2015; DOI: https://doi.org/10.4150/KPMI.2015.22.6.420

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Rare-earth zirconates, such as lanthanum zirconates and gadolinium zirconates, have been intensively investigated due to their excellent properties of low thermal conductivity as well as chemical stability at high temperature, which can make these materials ones of the most promising candidates for next-generation thermal barrier coating applications. In this study, three compositions, lanthanum/gadolinium zirconates with reduced rare-earth contents from stoichiometric RE₂Zr₂O₇ compositions, are fabricated via solid state reaction as well as sintering at 1600°C for 4 hrs. The phase formation, microstructure, and thermo-physical properties of three oxide ceramics are examined. In particular, each oxide ceramics exhibits composite structures between pyrochlore and fluorite phases. The potential of lanthanum/ gadolinium zirconate ceramics for TBC applications is also discussed.

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Rare earth zirconate nanostructures: Recent development on preparation and photocatalytic applications
Sahar Zinatloo-Ajabshir, Masoud Salavati-Niasari, Azam Sobhani, Zahra Zinatloo-Ajabshir
Journal of Alloys and Compounds.2018; 767: 1164. CrossRef
A novel Co-ions complexation method to synthesize pyrochlore La 2 Zr 2 O 7
Chunhui Xu, Hongyun Jin, Qifeng Zhang, Can Huang, Daifeng Zou, Fujian He, Shuen Hou
Journal of the European Ceramic Society.2017; 37(8): 2871. CrossRef
Fabrication and Characteristics of Thermal Barrier Coatings in the La2O3-Gd2O3-ZrO2System by Using Suspension Plasma Spray with Different Suspension Preparations
Soyul Lee, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Sahn Nahm, Seongwon Kim
Journal of the Korean institute of surface engineering.2016; 49(6): 595. 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; J Korean Powder Metall Inst. 2015;22(6):413-419. Published online December 1, 2015; DOI: https://doi.org/10.4150/KPMI.2015.22.6.413

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Lanthanum zirconate, La₂Zr₂O₇, is one of the most promising candidates for next-generation thermal barrier coating (TBC) applications in high efficient gas turbines due to its low thermal conductivity and chemical stability at high temperature. In this study, bulk specimens and thermal barrier coatings are fabricated via a variety of sintering processes as well as suspension plasma spray in lanthanum zirconates with reduced rare-earth contents. The phase formation, microstructure, and thermo-physical properties of these oxide ceramics and coatings are examined. In particular, lanthanum zirconates with reduced rare-earth contents in a La₂Zr₂O₇-4YSZ composite system exhibit a single phase of fluorite or pyrochlore after fabricated by suspension plasma spray or spark plasma sintering. The potential of lanthanum zirconate ceramics for TBC applications is also discussed.

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Phase Formation and Thermo-physical Properties of Lanthanum/Gadolinium Zirconate with Reduced Rare-earth Contents for Thermal Barrier Coatings
Sujin Lee, Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Sahn Nahm, Seongwon Kim
Journal of Korean Powder Metallurgy Institute.2015; 22(6): 420. CrossRef

Effect of the SiC Size on the Thermal and Mechanical Properties of Reaction-bonded Silicon Carbide Ceramics: Chang-Sup Kwon, Yoon-Suk Oh, Sung-Min Lee, Yoonsoo Han, Hyun-Ick Shin, Youngseok Kim, Seongwon Kim; J Korean Powder Metall Inst. 2014;21(6):467-472. Published online December 1, 2014; DOI: https://doi.org/10.4150/KPMI.2014.21.6.467

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RBSC (reaction-bonded silicon carbide) represents a family of composite ceramics processed by infiltrating with molten silicon into a skeleton of SiC particles and carbon in order to fabricate a fully dense body of silicon carbide. RBSC has been commercially used and widely studied for many years, because of its advantages, such as relatively low temperature for fabrication and easier to form components with near-net-shape and high relative density, compared with other sintering methods. In this study, RBSC was fabricated with different size of SiC in the raw material. Microstructure, thermal and mechanical properties were characterized with the reaction-sintered samples in order to examine the effect of SiC size on the thermal and mechanical properties of RBSC ceramics. Especially, phase volume fraction of each component phase, such as Si, SiC, and C, was evaluated by using an image analyzer. The relationship between microstructures and physical properties was also discussed.

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Structural and Mechanical Properties of SiC-Rich By-Products of the Metal Grade Si Process
Thomas Hafner, Jonas Hafner, Frank Kimm, Vira Bovda, Oleksandr Bovda, Oleksandr Kuprin, Anatoliy Pikalov, Kostiantyn Lentsov, Pavlo Schikhaylo, Yriy Onyschuk, Andriy Tarasuk, Viktoriya Podhurska, Bogdan Vasyliv, Oleksandr Shcheretsky, Ihor Vorona, Roman Y
Materials Science Forum.2024; 1113: 87. CrossRef
Effect of Y2O3 Additive Amount on Densification of Reaction Bonded Silicon Carbides Prepared by Si Melt Infiltration into All Carbon Preform
Kyeong-Sik Cho, Min-Ho Jang
Korean Journal of Materials Research.2021; 31(5): 301. CrossRef
Mechanical Strength Values of Reaction-Bonded-Silicon-Carbide Tubes with Different Sample Size
Seongwon Kim, Soyul Lee, Yoon-Suk Oh, Sung-Min Lee, Yoonsoo Han, Hyun-Ick Shin, Youngseok Kim
Journal of Korean Powder Metallurgy Institute.2017; 24(6): 450. 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 Korean Powder Metall Inst. 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

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 Korean Powder Metall Inst. 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

Phase Evolution and Thermal Conductivities of (La_1-xGd_x)₂Zr₂O₇ Oxides for Thermal Barrier Coatings: Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seong Won Kim; J Korean Powder Metall Inst. 2012;19(6):429-434.; DOI: https://doi.org/10.4150/KPMI.2012.19.6.429

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With increase in operating temperature of gas turbine for higher efficiency, it is necessary to find new materials of TBC for replacement of YSZ. Among candidate materials for future TBCs, zirconate-based oxides with pyrochlore and fluorite are prevailing ones. In this study, phase structure and thermal conductivities of (La_1-xGd_x)_2Zr_2O_7 oxide system are investigated. (La_1-xGd_x)_2Zr_2O_7 system are comprised by selecting La3+/Gd3+ as A-site ions and Zr4+ as B-site ion in A_2B_2O_7 pyrochlore structures. With powder mixture from each oxide, (La_1-xGd_x)_2Zr_2O_7 oxides are fabricated via solid-state reaction at 1600°C. Either pyrochlore or fluorite or mixture of both appears after heat treatment. For the developed phases along (La_1-xGd_x)_2Zr_2O_7 compositions, thermal conductivities are examined, with which the potential of (La_1-xGd_x)_2Zr_2O_7 compositions for TBC application is also discussed.

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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
Preparation of Suspension in La2O3-Gd2O3-ZrO2System via Planetary Mill and Characteristics of (La1-xGdx)2Zr2O7Coatings Fabricated via Suspension Plasma Spray
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim
Journal of Korean Powder Metallurgy Institute.2013; 20(6): 453. 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
Journal of Korean Powder Metallurgy Institute.2013; 20(6): 445. CrossRef

Effect of the Size and Amount of SiC on the Microstructures and Thermal Conductivities of ZrB₂-SiC Composite Ceramics: Seong-Won Kim, Chang-Sup Kwon, Yoon-Suk Oh, Sung-Min Lee, Hyung-Tae Kim; J Korean Powder Metall Inst. 2012;19(5):379-384.; DOI: https://doi.org/10.4150/KPMI.2012.19.5.379

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This paper reports the microstructures and thermal conductivities of ZrB_2-SiC composite ceramics with size and amount of SiC. We fabricated sintered bodies of ZrB_2-x vol.% SiC (x=10, 20, 30) with submicron and nanosized SiC densified by spark plasma sintering. Microstructure retained the initial powder size of especially SiC, except the agglomeration of nanosized SiC. For sintered bodies, thermal conductivities were examined. The observed thermal conductivity values are 40~60 W/mK, which is slightly lower than the reported values. The relation between microstructural parameter and thermal conductivity was also discussed.

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Analysis of Polymer Hybrid-coated Anodic Aluminum Oxide
Mira Kim, Yeongwoo Kim, Hakyoung Lee, Chan-Young Park, Won-Ki Lee, Taeho Kang, Kwon Taek Lim
Molecular Crystals and Liquid Crystals.2015; 622(1): 120. CrossRef
Thermal Properties of Diamond Aligned Electroless Ni Plating Layer/Oxygen Free Cu Substrates
Da-Woon Jeong, Song-Yi Kim, Kyoung-Tae Park, Seok-Jun Seo, Taek Soo Kim, Bum Sung Kim
Journal of Korean Powder Metallurgy Institute.2015; 22(2): 134. CrossRef
Effect of the SiC Size on the Thermal and Mechanical Properties of Reaction-bonded Silicon Carbide Ceramics
Chang-Sup Kwon, Yoon-Suk Oh, Sung-Min Lee, Yoonsoo Han, Hyun-Ick Shin, Youngseok Kim, Seongwon Kim
Journal of Korean Powder Metallurgy Institute.2014; 21(6): 467. CrossRef

The Effect of Sintering Processes and Additives on the Microstructures and Mechanical Properties of ZrB₂-SiC Composite Ceramics: Chang-Sup Kwon, Jung-Min Chae, Hyung-Tae Kim, Kyung-Ja Kim, Seong-Won Kim; J Korean Powder Metall Inst. 2011;18(6):562-567.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.562

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This paper reports the effect of sintering processes and additives on the microstructures and mechanical properties of ZrB_2-SiC composite ceramics. We fabricated sintered bodies of ZrB_2-20 vol.% SiC with or without sintering additive, such as C or B_4C, densified by spark plasma sintering as well as hot pressing. While almost full densification was achieved regardless of sintering processes or sintering additives, significant grain growth was observed in the case of spark plasma sintering, especially with B_4C. With sintered bodies, mechanical properties, such as flexural strength and Vickers hardness, were also examined.

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Citations to this article as recorded by

Effect of the Size and Amount of SiC on the Microstructures and Thermal Conductivities of ZrB2-SiC Composite Ceramics
Seong-Won Kim, Chang-Sup Kwon, Yoon-Suk Oh, Sung-Min Lee, Hyung-Tae Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(5): 379. CrossRef

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