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UHT ceramics are essential for aerospace, energy, and power applications, where maintaining mechanical integrity under extreme thermal conditions is critical. Bulk NbB₂ ceramics, consolidated via SPS at 1900 °C, achieved 98% density and 6 µm grains, with flexural strength around 420 MPa from room temperature up to 1600 °C, increasing to 430 MPa at 1700 °C before failure at 1800 °C. TaB₂ with grains of 3–7 µm, SPSed at 2000–2200 °C, displayed strength variations of about 50 MPa up to 1800 °C and exhibited elastic fracture below 1900 °C, with strength rising to 400 MPa. Above 1900 °C, strength became dependent on loading rate, and mixed fracture was observed only in 2200 °C specimens. Reactive SPS processed at 2150 °C yielded bulk TaB with high hardness (18.5 GPa), toughness (9.8 MPa·m¹ᐟ²), and strength increasing from 330 MPa to 425 MPa at 1800 °C. TiB₂–NbB₂ composites showed strengths of 330 MPa at room temperature and about 400 MPa at 1200–1600 °C, shifting to plastic fracture at 1800 °C. A hierarchical Zr–Ta multiboride demonstrated hardness between 22–28 GPa and strength around 400 MPa up to 2000 °C. All these systems maintained nearly temperature-independent strength up to 1800–2000 °C, underscoring their suitability for extreme environments.

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Keyword: Transition Metal Diborides, Ultra‑High‑Temperature Deformation Resistivity, SPS

Conference: 公益社団法人 日本セラミックス協会2026年年会 (2026-03-04 - 2026-03-06)

Funding:

• NIMS AB3080 ( 多結晶光学材料 Research toward Innovative Optical Materials)
• JSPS KCB101 (非晶質相形成による超高温セラミックスの高 KAKENHI Grants-in-Aid for Scientific Research 24K08035.)

Manuscript type: Not a journal article

MDR DOI: https://doi.org/10.48505/nims.6228

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Updated at: 2026-03-21 08:30:41 +0900

Published on MDR: 2026-03-20 21:43:43 +0900