Journal of Powder Materials

Byung-Koog Jang

4 Articles

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

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

Phase Evolution and Thermo-physical Properties of La₂(Zr_1-xHf_x)₂O₇ Oxides for Thermal Barrier Coatings: Seong-Won Kim, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang; J Korean Powder Metall Inst. 2011;18(6):568-574.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.568

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As operating temperatures of engines or turbines continually increase for higher efficiency, significant amounts of researches have been focused on finding new materials, which would be alternatives to conventional yttria-stabilized zirconia (YSZ) for thermal barrier coatings (TBCs). In this study, phase evolution and thermo-physical properties of La_2(Zr_1-xHf_x)_2O_7 pyrochlore systems are investigated for TBC applications. La_2(Zr_1-xHf_x)_2O_7 systems are comprised by selecting La3+ as A-site ions and Zr4+/Hf4+ as B-site ions in A_2B_2O_7 pyrochlore structures. For the developed phases in La_2(Zr_1-xHf_x)_2O_7 compositions, thermo-physical properties such as thermal conductivity, thermal expansion coefficient are examined. The potential of these La_2(Zr_1-xHf_x)_2O_7 compositions for TBC application is also discussed.

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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
Phase Evolution and Thermal Conductivities of (La1-xGdx)2Zr2O7Oxides for Thermal Barrier Coatings
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seong Won Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 429. CrossRef

Phase Evolution and Thermo-physical Properties of Rare-earth Oxides for Thermal Barrier Systems: Byung-Chul Shim, Kil-Ho Kwak, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seong-Won Kim; J Korean Powder Metall Inst. 2010;17(2):148-153.; DOI: https://doi.org/10.4150/KPMI.2010.17.2.148

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Thermal barrier systems have been widely investigated over the past decades, in order to enhance reliability and efficiency of gas turbines at higher temperatures. Yttria-stabilized zirconia (YSZ) is one of the most leading materials as the thermal barriers due to its low thermal conductivity, thermodynamic stability, and thermal compatibility with metal substrates. In this work, rare-earth oxides with pyrochlore phases for thermal barrier systems were investigated. Pyrochlore phases were successfully formed via solid-state reactions started from rare-earth oxide powders. For the heat-treated samples, thermo-physical properties were examined. These rare-oxide oxides showed thermal expansion of 9sim12times10-6/K and thermal conductivity of 1.2~2.4 W/mK, which is comparable with the thermal properties of YSZ.

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Phase Evolution and Thermal Conductivities of (La1-xGdx)2Zr2O7Oxides for Thermal Barrier Coatings
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seong Won Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 429. CrossRef
Phase Evolution and Thermo-physical Properties of La2(Zr1-xHfx)2O7Oxides for Thermal Barrier Coatings
Seong-Won Kim, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang
Journal of Korean Powder Metallurgy Institute.2011; 18(6): 568. CrossRef

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