Si3N4-SiC composite ceramics were fabricated by chemical vapor infiltration using porous Si3Na ceramic as preform. The average grain size of SiC was 30 nm. Relationship between SiC content and relative complex permitt...Si3N4-SiC composite ceramics were fabricated by chemical vapor infiltration using porous Si3Na ceramic as preform. The average grain size of SiC was 30 nm. Relationship between SiC content and relative complex permittivity of Si3Na-SiC within the frequency range of 8.2-12.4 GHz （X-band） was investigated. The average real part of relative complex permittivity ε′ of Si3N4-SiC increased from 3.7 to 14.9 and the relative imaginary part ε″ increased from 0.017 to 13.4 when the content of SiC increased from 0 to 10 vol.%. The Si3N4-SiC ceramic with 3 vol.% SiC achieved a reflection loss below -10 dB （90% absorption） at 8.0-11.4 GHz, and the minimum value was -27.1 dB at 9.8 GHz when the sample thickness was 2.5 mm. The excellent microwave absorbing abilities of Si3N4-SiC ceramic were attributed to the interfacial polarization at interface between Si3N4 and SiC and at grain boundary between SiC nanocrystals.展开更多
基金financial support from the National University Student Innovation Program fund (No. 101069911)supported by the Research Fund of State Key Laboratory of Solidification Processing in Northwestern Polytechnical University (No. KB200920)+1 种基金the China Postdoctoral Science Foundation (No. 20110491683)the 111 Project(B08040)
文摘Si3N4-SiC composite ceramics were fabricated by chemical vapor infiltration using porous Si3Na ceramic as preform. The average grain size of SiC was 30 nm. Relationship between SiC content and relative complex permittivity of Si3Na-SiC within the frequency range of 8.2-12.4 GHz （X-band） was investigated. The average real part of relative complex permittivity ε′ of Si3N4-SiC increased from 3.7 to 14.9 and the relative imaginary part ε″ increased from 0.017 to 13.4 when the content of SiC increased from 0 to 10 vol.%. The Si3N4-SiC ceramic with 3 vol.% SiC achieved a reflection loss below -10 dB （90% absorption） at 8.0-11.4 GHz, and the minimum value was -27.1 dB at 9.8 GHz when the sample thickness was 2.5 mm. The excellent microwave absorbing abilities of Si3N4-SiC ceramic were attributed to the interfacial polarization at interface between Si3N4 and SiC and at grain boundary between SiC nanocrystals.
