کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1462001 | 989625 | 2012 | 6 صفحه PDF | دانلود رایگان |
Si3N4–SiCN composite ceramics were successfully fabricated through precursor infiltration pyrolysis (PIP) method using polysilazane as precursor and porous Si3N4 as preform. After annealed at temperatures varying from 900 °C to 1400 °C, the phase composition of SiCN ceramics, electrical conductivity and dielectric properties of Si3N4–SiCN composite ceramics over the frequency range of 8.2–12.4 GHz (X-band) were investigated. With the increase of annealing temperature, the content of amorphous SiCN decreases and that of N-doped SiC nano-crystals increases, which leads to the increase of electrical conductivity. After annealed at 1400 °C, the average real and imaginary permittivities of Si3N4–SiCN composite ceramics are increased from 3.7 and 4.68 × 10−3 to 8.9 and 1.8, respectively. The permittivities of Si3N4–SiCN composite ceramics show a typical ternary polarization relaxation, which are ascribed to the electric dipole and grain boundary relaxation of N-doped SiC nano-crystals, and dielectric polarization relaxation of the in situ formed graphite. The Si3N4–SiCN composite ceramics exhibit a promising prospect as microwave absorbing materials.
Journal: Ceramics International - Volume 38, Issue 7, September 2012, Pages 6015–6020