Effect of fabrication atmosphere on dielectric properties of SiC/SiC composites

Silicon carbide fiber reinforced silicon carbide (SiC/SiC) composites were prepared in hydrogen or argon atmosphere by chemical vapor deposition, using methytrichloridesilane as reactant precursor. The dielectric properties of the fabricated SiC/SiC composites were investigated in the frequency range of 8.2-12.4 GHz. The results show that stoichiometric and carbon rich SiC matrixes are obtained in hydrogen and argon atmosphere, respectively. The direct current conductivity, relative permittivity (ε′) and dissipation factor (tan δ) of the composites with carbon rich matrix are higher than those of the composites with stoichiometric matrix.