Abstract
Dual phase (Hf,Ta,Ti,W,Zr)B2-(Hf,Ta,Ti,W,Zr)C high entropy ultra-high temperature ceramics were processed from commercial diboride and carbide powders with and without SiC additions. A 30-min hold at a maximum temperature of 1850 °C in spark plasma sintering resulted in a relative density of ∼95 %, which increased to ∼100 % with the addition of 7.5 wt.% SiC. The compositions did not reach chemical equilibrium under the given sintering conditions resulting in an inhomogeneous distribution of transition metals in both the boride and carbide phases. The addition of SiC improved densification by inhibiting grain growth, which reduced the grain size from 9.0 ± 4.2 μm without SiC to 5.6 ± 2.5 μm with SiC. The addition of SiC also improved both microhardness and fracture toughness. Microhardness at the maximum indentation load of 10 N increased from 20.3 ± 0.6 GPa without SiC to 22.6 ± 0.6 GPa with SiC, while indentation fracture toughness increased from 2.2 ± 0.3 MPa m1/2 to 4.0 ± 0.9 MPa m1/2. The room temperature thermal conductivity of the dual phase high entropy ceramic was ∼15 W/(m.K) due to the high entropy effect which increased to ∼22 W/(m.K) with the addition of SiC. The addition of SiC enhanced densification, inhibited grain growth, improved mechanical properties, and increased thermal conductivity of the dual phase high entropy system.
Recommended Citation
R. Hassan et al., "SiC Addition to a Dual Phase High Entropy Ultra-high Temperature Ceramic," Ceramics International, Elsevier, Jan 2024.
The definitive version is available at https://doi.org/10.1016/j.ceramint.2024.10.430
Department(s)
Materials Science and Engineering
Keywords and Phrases
High entropy ceramics; Silicon carbide; Spark plasma sintering; Ultra-high temperature ceramics
International Standard Serial Number (ISSN)
0272-8842
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2024 Elsevier, All rights reserved.
Publication Date
01 Jan 2024
Comments
United States - India Educational Foundation, Grant 2990 FNPDR/2023