Porous (Y0.25Ho0.25Yb0.25Lu0.25)2Si2O7: A novel high‐entropy ceramic with high porosity and excellent thermal stability

With the rapid development of hypersonic vehicles, the thermal protection systems face great challenges due to the severe aerodynamic heat. As a result, conventional fiber insulation tiles would experience severe shrinkage at high temperatures (>1500°C), endangering the safety of the aircraft. To...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2024-10, Vol.107 (10), p.6921-6929
Main Authors: Zhou, Jiaxin, Zeng, Dawei, Wu, Zhen, Sun, Luchao, Wang, Jingyang
Format: Article
Language:English
Subjects:
Activated sintering
Aerodynamic stability
Dimensional stability
Entropy
good high‐temperature stability
High temperature
high‐entropy (Y0.25Ho0.25Yb0.25Lu0.25)2Si2O7 ceramic
Hypersonic vehicles
low thermal conductivity
Porosity
Porous materials
superhigh porosity
Thermal conductivity
Thermal insulation
Thermal protection
Thermal resistance
Thermal stability
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Summary:With the rapid development of hypersonic vehicles, the thermal protection systems face great challenges due to the severe aerodynamic heat. As a result, conventional fiber insulation tiles would experience severe shrinkage at high temperatures (>1500°C), endangering the safety of the aircraft. To solve the problem, a high‐entropy effect was introduced to increase the high‐temperature resistance of thermal insulation materials, and highly porous (Y0.25Ho0.25Yb0.25Lu0.25)2Si2O7 was prepared by in situ reaction sintering process in this work. The fabricated porous samples present excellent overall properties, including superhigh porosity (95.09%–93.10%), lightweight (0.29–0.41 g/cm3), and very low thermal conductivity (0.066–0.085 W/(m·K)). More importantly, porous (Y0.25Ho0.25Yb0.25Lu0.25)2Si2O7 has outstanding high‐temperature dimensional stability. Although the porosity of the sample is higher than 90%, its linear shrinkage at 1550°C for 2 h is less than 1%. The results demonstrate that porous high‐entropy (Y0.25Ho0.25Yb0.25Lu0.25)2Si2O7 is a promising thermal insulation material in extreme high‐temperature environments. This work develops a new style of high‐temperature resistance thermal insulation material, and the prepared porous high‐entropy (Y0.25Ho0.25Yb0.25Lu0.25)2Si2O7 ceramic has the merits of superhigh porosity, lightweight, high strength, and very low thermal conductivity. Especially, the new material has excellent high‐temperature dimensional stability (shrinkage 
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.19955