Improved electromagnetic absorbing properties of Si3N4–SiC/SiO2 composite ceramics with multi-shell microstructure |
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| Authors: | Guopeng Zheng Xiaowei Yin Shanhua Liu Xingmin Liu Juanli Deng Quan Li |
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| Affiliation: | 1. Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, PR China;2. School of Materials Science and Engineering, Chang’an University, Xi’an, Shaanxi 710072, PR China |
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| Abstract: | Porous Si3N4–SiC composite ceramic was fabricated by infiltrating SiC coating with nano-scale crystals into porous β-Si3N4 ceramic via chemical vapor infiltration (CVI). Silica (SiO2) film was formed on the surface of rod-like Si3N4–SiC grains during oxidation at 1100 °C in air. The as-received Si3N4–SiC/SiO2 composite ceramic attains a multi-shell microstructure, and exhibits reduced impedance mismatch, leading to excellent electromagnetic (EM) absorbing properties. The Si3N4–SiC/SiO2 fabricated by oxidation of Si3N4–SiC for 10 h in air can achieve a reflection loss of ?30 dB (>99.9% absorption) at 8.7 GHz when the sample thickness is 3.8 mm. When the sample thickness is 3.5 mm, reflection loss of Si3N4–SiC/SiO2 is lower than ?10 dB (>90% absorption) in the frequency range 8.3–12.4 GHz, the effective absorption bandwidth is 4.1 GHz. |
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| Keywords: | SiC Complex permittivity Reflection loss |
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