Preparation and dielectric properties of Si3N4/SiCw composite ceramic |
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Authors: | Weiling Xiao Peng Xiao Heng Luo Wei Zhou Yang Li |
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Affiliation: | 1. State Key Laboratory for Powder Metallurgy, Central South University, Changsha, 410083, China 2. Wuhan Electromagnetism Ltd. Company of China Aerospace Science and Industry Corporation, Wuhan, 430074, China
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Abstract: | Gelcasting was employed to fabricate Si3N4/SiC whisker (SiCw) composite ceramics, and the effects of heat-treatment temperature on the length-to-diameter ratio of the whiskers and SiCw content on microwave dielectric properties were studied. Compared with pure SiCw of spherical structure obtained at temperature of 1,750 °C(Ar), pure SiCw treated at 1,600 °C(Ar) showed rod-like structure, higher dielectric properties and more evenly distribution in Si3N4/SiCw composite ceramics. Both the real (ε′) and imaginary (ε″) permittivity of Si3N4/SiC whisker (SiCw) composite ceramics decreased with increasing frequency and increased as the whisker content raised owing to the interface and SiCw playing a role of dipole in the frequency range of 8.2–12.4 GHz. In addition, comparing the ceramics with lower content of SiCw, the reflectivity of the composite ceramics moved to a lower frequency; the maximum absorption peak reached ?22.4 dB at the whisker content of 15 wt%. |
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