Two types of silicon carbide fibers (SiCf) were prepared employing different pyrolysis techniques. The relationship between the microstructure and the electrical resistivity of the fibers was investigated. The results indicated that the carbon layer present on the fiber surface acted as the main conductive phase in the SiCf obtained by direct pyrolysis, whereas a free carbon phase determined the conductivity of the SiCf prepared by the preheated pyrolysis method. A core‐shell model and a general effective media (GEM) theory were proposed to explain the conductivity of different types of SiCf. Quantitative analysis based on these models indicated an electrical resistivity of ~10−2 Ω·cm for the carbon layer on the surface of SiCf obtained by direct pyrolysis. The electrical resistivity and the percolation threshold of the free carbon in SiCf prepared by the preheated pyrolysis method were 10−1 Ω·cm and 11.3% respectively.
Two types of silicon carbide fibers with sinusoidal electrical resistivity were prepared by using different pyrolysis technology. The relationship between the microstructure and the electrical resistivity of these fibers was investigated and compared. The results indicated that carbon layer was the main conductive phase in the SiC fibers obtained by means of one step pyrolysis, whereas a free carbon phase governed the conductivity of the SiC fibers prepared through two step pyrolysis mode.
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