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During the spark plasma sintering at 1900 °C, SiB6 decomposes into cubic silicon carbide and boron carbide, owing to the reducing environment of the furnace. For the HfB2-SiB6 ceramic improvement in hardness (24.5 ± 0.7 GPa) was attributed to the formation of the B12(C,Si,B)3. Fracture toughness by indentation (6.8 ± 2.4 MPa·m1/2), single-edge notched bend specimens (4.6 ± 0.4 MPa·m1/2) and room-temperature strength (513 ± 21 MPa) of the HfB2–SiB6 composite produced by spark plasma sintering was higher or on the same level as the HfB2–SiC ceramics. The high-temperature flexural strength tests suggested that the strength would decrease monotonically with an increase in temperature. At or below 1600 °C, only a linear stress-strain response was observed, and resulted into a mean strength of ~320 MPa. During the tests at 1800 °C, we observed a nonlinear deformation indicating ongoing plastic deformation which led to a strength decrease down to 230 ± 30 MPa.

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

  © 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

Keyword: hafnium diboride, reactive decomposition, silicon hexaboride, flexural strength, hightemperature materials

Date published: 2022-05-05

Publisher: Elsevier BV

Journal:

• Journal of the European Ceramic Society (ISSN: 09552219) vol. 42 issue. 12 p. 4783-4792

Funding:

• NIMS PA3030 (粉体・セラミックス 結晶・界面の階層的構造制御による機能顕在化のための研究 80)
• NIMS PA5180 (セラミックスプロセッシング - 20 )

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4968

First published URL: https://doi.org/10.1016/j.jeurceramsoc.2022.05.004

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Updated at: 2024-11-16 08:31:04 +0900

Published on MDR: 2024-11-16 08:31:04 +0900