Consolidation and high-temperature strength of monolithic lanthanum hexaboride

Dmytro Demirskyi; Tohru S. Suzuki; Kyosuke Yoshimi; Oleg O. Vasylkiv

doi:10.1111/jace.18331

Consolidation and high-temperature strength of monolithic lanthanum hexaboride

Dmytro Demirskyi^*, Tohru S. Suzuki, Kyosuke Yoshimi, Oleg O. Vasylkiv

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

In this study we explored the densification, microstructure evolution, and high-temperature properties of bulk lanthanum hexaboride. LaB₆ bulks were consolidated using spark-plasma sintering only in the temperature range between 1400°C and 1700°C. We adopted flash spark plasma sintering (SPS) of LaB₆ using a direct current heating without a graphite die. We observed a peculiar grain-size gradient when coarse grains exceeding 300 μm were observed on the top side of the specimen, while the bottom side had a grain size of 15–20 μm. Such large grain was not observed using SPS at 2000°C, suggesting that these might originate from a local overheating. Based on the three-point flexural tests, it was observed that the toughness and strength of the LaB₆ were acceptable at room-temperature (3.1 ± 0.2 MPa m^1/2, 300 ± 20 MPa). However, at 1600°C, these parameters would decrease to 1.3 ± 0.1 MPa m^1/2 and 120 ± 40 MPa, respectively.

Original language	English
Pages (from-to)	4277-4290
Number of pages	14
Journal	Journal of the American Ceramic Society
Volume	105
Issue number	6
DOIs	https://doi.org/10.1111/jace.18331
Publication status	Published - 2022 Jun
Externally published	Yes

Keywords

borides
densification
flash sintering
grain growth
spark plasma sintering

ASJC Scopus subject areas

Ceramics and Composites
Materials Chemistry

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10.1111/jace.18331

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@article{1c9979f893674677802b8ffa814a5dda,

title = "Consolidation and high-temperature strength of monolithic lanthanum hexaboride",

abstract = "In this study we explored the densification, microstructure evolution, and high-temperature properties of bulk lanthanum hexaboride. LaB6 bulks were consolidated using spark-plasma sintering only in the temperature range between 1400°C and 1700°C. We adopted flash spark plasma sintering (SPS) of LaB6 using a direct current heating without a graphite die. We observed a peculiar grain-size gradient when coarse grains exceeding 300 μm were observed on the top side of the specimen, while the bottom side had a grain size of 15–20 μm. Such large grain was not observed using SPS at 2000°C, suggesting that these might originate from a local overheating. Based on the three-point flexural tests, it was observed that the toughness and strength of the LaB6 were acceptable at room-temperature (3.1 ± 0.2 MPa m1/2, 300 ± 20 MPa). However, at 1600°C, these parameters would decrease to 1.3 ± 0.1 MPa m1/2 and 120 ± 40 MPa, respectively.",

keywords = "borides, densification, flash sintering, grain growth, spark plasma sintering",

author = "Dmytro Demirskyi and Suzuki, {Tohru S.} and Kyosuke Yoshimi and Vasylkiv, {Oleg O.}",

note = "Funding Information: The authors express their sincere appreciation to Dr. Toshiyuki Nishimura (NIMS) for providing access to the evaluation of high-temperature strength; this study would not be as complete otherwise. Dmytro Demirskyi expresses his gratitude to Dr. Byung-Nam Kim (NIMS) for his comments on the structure evolution during the flash spark plasma sintering. D.D. was supported by Core Research Cluster for Materials Science, Tohoku University, Japan. Funding Information: The authors express their sincere appreciation to Dr. Toshiyuki Nishimura (NIMS) for providing access to the evaluation of high‐temperature strength; this study would not be as complete otherwise. Dmytro Demirskyi expresses his gratitude to Dr. Byung‐Nam Kim (NIMS) for his comments on the structure evolution during the flash spark plasma sintering. D.D. was supported by Core Research Cluster for Materials Science, Tohoku University, Japan. Publisher Copyright: {\textcopyright} 2022 The American Ceramic Society.",

year = "2022",

month = jun,

doi = "10.1111/jace.18331",

language = "English",

volume = "105",

pages = "4277--4290",

journal = "Journal of the American Ceramic Society",

issn = "0002-7820",

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number = "6",

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T1 - Consolidation and high-temperature strength of monolithic lanthanum hexaboride

AU - Demirskyi, Dmytro

AU - Suzuki, Tohru S.

AU - Yoshimi, Kyosuke

AU - Vasylkiv, Oleg O.

N1 - Funding Information: The authors express their sincere appreciation to Dr. Toshiyuki Nishimura (NIMS) for providing access to the evaluation of high-temperature strength; this study would not be as complete otherwise. Dmytro Demirskyi expresses his gratitude to Dr. Byung-Nam Kim (NIMS) for his comments on the structure evolution during the flash spark plasma sintering. D.D. was supported by Core Research Cluster for Materials Science, Tohoku University, Japan. Funding Information: The authors express their sincere appreciation to Dr. Toshiyuki Nishimura (NIMS) for providing access to the evaluation of high‐temperature strength; this study would not be as complete otherwise. Dmytro Demirskyi expresses his gratitude to Dr. Byung‐Nam Kim (NIMS) for his comments on the structure evolution during the flash spark plasma sintering. D.D. was supported by Core Research Cluster for Materials Science, Tohoku University, Japan. Publisher Copyright: © 2022 The American Ceramic Society.

PY - 2022/6

Y1 - 2022/6

N2 - In this study we explored the densification, microstructure evolution, and high-temperature properties of bulk lanthanum hexaboride. LaB6 bulks were consolidated using spark-plasma sintering only in the temperature range between 1400°C and 1700°C. We adopted flash spark plasma sintering (SPS) of LaB6 using a direct current heating without a graphite die. We observed a peculiar grain-size gradient when coarse grains exceeding 300 μm were observed on the top side of the specimen, while the bottom side had a grain size of 15–20 μm. Such large grain was not observed using SPS at 2000°C, suggesting that these might originate from a local overheating. Based on the three-point flexural tests, it was observed that the toughness and strength of the LaB6 were acceptable at room-temperature (3.1 ± 0.2 MPa m1/2, 300 ± 20 MPa). However, at 1600°C, these parameters would decrease to 1.3 ± 0.1 MPa m1/2 and 120 ± 40 MPa, respectively.

AB - In this study we explored the densification, microstructure evolution, and high-temperature properties of bulk lanthanum hexaboride. LaB6 bulks were consolidated using spark-plasma sintering only in the temperature range between 1400°C and 1700°C. We adopted flash spark plasma sintering (SPS) of LaB6 using a direct current heating without a graphite die. We observed a peculiar grain-size gradient when coarse grains exceeding 300 μm were observed on the top side of the specimen, while the bottom side had a grain size of 15–20 μm. Such large grain was not observed using SPS at 2000°C, suggesting that these might originate from a local overheating. Based on the three-point flexural tests, it was observed that the toughness and strength of the LaB6 were acceptable at room-temperature (3.1 ± 0.2 MPa m1/2, 300 ± 20 MPa). However, at 1600°C, these parameters would decrease to 1.3 ± 0.1 MPa m1/2 and 120 ± 40 MPa, respectively.

KW - borides

KW - densification

KW - flash sintering

KW - grain growth

KW - spark plasma sintering

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JO - Journal of the American Ceramic Society

JF - Journal of the American Ceramic Society

IS - 6

ER -

Consolidation and high-temperature strength of monolithic lanthanum hexaboride

Abstract

Keywords

ASJC Scopus subject areas

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