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Fabrication of SiCf/SiC Composites with a BN Interphase Prepared by the Wet Method
Kyung Ho Kim, Yoonsoo Han
J Powder Mater. 2024;31(6):530-536.   Published online December 31, 2024
DOI: https://doi.org/10.4150/jpm.2024.00339
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This study presents a cost-effective wet chemical coating process for fabricating a boron nitride (BN) interphase on silicon carbide (SiC) fibers, increasing the oxidation resistance and performance of SiCf/SiC ceramic matrix composites. Using urea as a precursor, optimal nitriding conditions were determined by adjusting the composition, concentration, and immersion time. X-ray diffraction analysis revealed distinct BN phase formation at 1300°C and 1500°C, while a mixture of BN and B₂O₃ was observed at 1200°C. HF treatment improved coating uniformity by removing SiO₂ layers formed during the de-sizing process. Optimization of the boric acid-to-urea molar ratio resulted in a uniform, 130-nm-thick BN layer. This study demonstrates that the wet coating process offers a viable and economical alternative to chemical vapor deposition for fabricating high-performance BN interphases in SiCf/SiC composites that are suitable for high-temperature applications.
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Fabrication of 3D Aligned h-BN based Polymer Composites with Enhanced Mechanical Properties for Battery Housing
Kiho Song, Hyunseung Song, Sang In Lee, Changui Ahn
J Powder Mater. 2024;31(4):329-335.   Published online August 30, 2024
DOI: https://doi.org/10.4150/jpm.2024.00220
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As the demand for electric vehicles increases, the stability of batteries has become one of the most significant issues. The battery housing, which protects the battery from external stimuli such as vibration, shock, and heat, is the crucial element in resolving safety problems. Conventional metal battery housings are being converted into polymer composites due to their lightweight and improved corrosion resistance to moisture. The transition to polymer composites requires high mechanical strength, electrical insulation, and thermal stability. In this paper, we proposes a high-strength nanocomposite made by infiltrating epoxy into a 3D aligned h-BN structure. The developed 3D aligned h-BN/epoxy composite not only exhibits a high compressive strength (108 MPa) but also demonstrates excellent electrical insulation and thermal stability, with a stable electrical resistivity at 200 °C and a low thermal expansion coefficient (11.46ⅹppm/℃), respectively.
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Effect of Abnormal Grain Growth on Ionic Conductivity in LATP
Hyungik Choi, Yoonsoo Han
J Powder Mater. 2024;31(1):23-29.   Published online February 28, 2024
DOI: https://doi.org/10.4150/KPMI.2024.31.1.23
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Grain Shape and Grain Growth Behavior in the (K0.5Na0.5)NbO3-CaZrO3 System
Chul-Lee Lee, Kyoung-Seok Moon
J Powder Mater. 2022;29(2):110-117.   Published online April 1, 2022
DOI: https://doi.org/10.4150/KPMI.2022.29.2.110
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The grain growth behavior in the (1-x)K0.5Na0.5NbO3-xCaZrO3 (KNNCZ-x) system is studied as a function of the amount of CZ and grain shape. The (1-x)K0.5Na0.5NbO3-xCaZrO3 (KNNCZ-x) powders are synthesized using a conventional solid-state reaction method. A single orthorhombic phase is observed at x = 0 – 0.03. However, rhombohedral and orthorhombic phases are observed at x = 0.05. The grain growth behavior changes from abnormal grain growth to the suppression of grain growth as the amount of CaZrO3 (CZ) increases. With increasing CZ content, grains become more faceted, and the step-free energy increases. Therefore, the critical growth driving force increases. The grain size distribution broadens with increasing sintering time in KNNCZ-0.05. As a result, some large grains with a driving force larger than the critical driving force for growth exhibit abnormal grain growth behavior during sintering. Therefore, CZ changes the grain growth behavior and microstructure of KNN. Grain growth at the faceted interface of the KNNCZ system occurs via two-dimensional nucleation and growth.

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Effect of Na2CO3 Addition on Grain Growth Behavior and Solid-state Single Crystal Growth in the Na0.5Bi0.5TiO3-BaTiO3 System
Kyoung-Seok Moon
J Korean Powder Metall Inst. 2018;25(2):104-108.   Published online April 1, 2018
DOI: https://doi.org/10.4150/KPMI.2018.25.2.104
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  • 2 Citations
AbstractAbstract PDF

Grain-growth behavior in the 95Na1/2Bi1/2TiO3-5BaTiO3 (mole fraction, NBT-5BT) system has been investigated with the addition of Na2CO3. When Na2CO3 is added to NBT-5BT, the growth rate is higher than desired and grains are already impinging each other during the initial stage of sintering. The grain size decreases as the sintering temperature increases. With the addition of Na2CO3, a liquid phase infiltrates the interfaces between grains during sintering. The interface structure can be changed to be more faceted and the interface migration rate can increase due to fast material transport through the liquid phase. As the sintering temperature increases, the impingement of abnormal grains increases because the number of abnormal grains increases. Therefore, the average grain size of abnormal grains can be decreased as the temperature increases. The phenomenon can provide evidence that grain coarsening in NBT-5BT with addition of Na2CO3 is governed by the growth of facet planes, which would occur via mixed control.

Citations

Citations to this article as recorded by  
  • Growth of single crystals in the (Na1/2Bi1/2)TiO3–(Sr1–xCax)TiO3 system by solid state crystal growth
    Phan Gia Le, Huyen Tran Tran, Jong-Sook Lee, John G. Fisher, Hwang-Pill Kim, Wook Jo, Won-Jin Moon
    Journal of Advanced Ceramics.2021; 10(5): 973.     CrossRef
  • Sintering Behavior of M-type Sr-Hexaferrite by MnCO3 Addition
    MinSeok Jeong, Changjae You, Jung Young Cho, Kyoung-Seok Moon
    Journal of Korean Powder Metallurgy Institute.2020; 27(2): 126.     CrossRef
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Synthesis of Boron Nitride Nanotubes via inductively Coupled thermal Plasma process Catalyzed by Solid-state ammonium Chloride
Mi Se Chang, Young Gyun Nam, Sangsun Yang, Kyung Tae Kim, Ji Hun Yu, Yong-Jin Kim, Jae Won Jeong
J Korean Powder Metall Inst. 2018;25(2):120-125.   Published online April 1, 2018
DOI: https://doi.org/10.4150/KPMI.2017.25.2.120
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AbstractAbstract PDF

Boron nitride nanotubes (BNNTs) are receiving great attention because of their unusual material properties, such as high thermal conductivity, mechanical strength, and electrical resistance. However, high-throughput and highefficiency synthesis of BNNTs has been hindered due to the high boiling point of boron (~ 4000°C) and weak interaction between boron and nitrogen. Although, hydrogen-catalyzed plasma synthesis has shown potential for scalable synthesis of BNNTs, the direct use of H2 gas as a precursor material is not strongly recommended, as it is extremely flammable. In the present study, BNNTs have been synthesized using radio-frequency inductively coupled thermal plasma (RF-ITP) catalyzed by solid-state ammonium chloride (NH4Cl), a safe catalyst materials for BNNT synthesis. Similar to BNNTs synthesized from h-BN (hexagonal boron nitride) + H2, successful fabrication of BNNTs synthesized from h-BN+NH4Cl is confirmed by their sheet-like properties, FE-SEM images, and XRD analysis. In addition, improved dispersion properties in aqueous solution are found in BNNTs synthesized from h-BN +NH4Cl.


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