Journal
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
Volume 42, Issue 4, Pages 1249-1257Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.jeurceramsoc.2021.12.011
Keywords
SiC-Si3N4 ceramics; Foam-gelcasting; Hierarchical pore structure; Dielectric property; Electromagnetic wave absorption
Categories
Funding
- National Natural Science Foundation of China [51802328, 52072386, 51902329]
- Natural Science Foundation of Shanghai [21ZR1472300]
- Youth Innovation Promotion Association CAS [2021248]
- Science Foundation for Youth Scholar of State Key Laboratory of High Performance Ceramics and Superfine Microstructures [SKL201801]
- Shanghai Sailing Program [19YF1454200]
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This study reports the X-band microwave absorbing properties of gelcasted SiC-Si3N4 ceramics with different hierarchical pore structures for the first time. The effects of pore structures, sample thickness, and temperature on the complex permittivity and microwave absorption performance of SiC-Si3N4 ceramics were systematically investigated. The results indicate that the introduction of appropriate hierarchical pore structure improves the absorbing performance of the material.
In this work, X-band microwave absorbing properties of gelcasted SiC-Si3N4 ceramics with different hierarchical pore structures at both room temperature and high temperature were reported for the first time. Effects of pore structures, sample thickness and temperature on complex permittivity and microwave absorption performance of SiC-Si3N4 ceramics were investigated systemically. The results suggested that the introduction of appropriate hierarchical pore structure was beneficial to improve the absorbing performance of the material. The minimum reflection loss value can reach -59.2 dB for the 3.8 mm thick sample at 8.35 GHz and room temperature. By elevating the temperature, the effective absorption bandwidth of porous SiC-Si3N4 with a thickness of 3.0 mm covers the entire X-band. The excellent microwave absorbing property of porous SiC-Si3N4 ceramics was attributed to the multiple reflections brought about by the existence of hierarchical pores, interfacial polarization between SiC and Si3N4 grains, and defect dipole polarization in grains and grain boundaries. The good absorbing property and the clarification of absorbing mechanism of porous gelcasted SiC-Si3N4 ceramics will provide a solid foundation for the development of porous SiC-based absorbing parts.
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