Abstract
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.
Highlights
The silicon carbide (SiC) fibers are typically used as reinforcement for high temperature structural ceramic composites due to their excellent tensile strength, stiffness and high temperature resistivity in oxidizing atmosphere
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
The auger electron spectroscopy (AES) analysis shows that a thin carbon layer appears for I-SiC fibers and the thickness of this carbon layer increases as the ρ of corresponding fibers decreases (Figure 5(a) and Figure 5(b))
Summary
The silicon carbide (SiC) fibers are typically used as reinforcement for high temperature structural ceramic composites due to their excellent tensile strength, stiffness and high temperature resistivity in oxidizing atmosphere. The specific resistivity of the fiber can be adjusted via heat treatment [2], surface modification [3] or heteroatom doping [4] [5], et al For example, the Nippon Carbon company produced a commercial type of SiC fibers (trade name: Nicalon NL-607) coated with a carbon layer. This fiber shows different ρ in the range of 10−1 103 Ω∙cm according to different carbon layer thickness [3]. The tunable electrical conductivity together with the excellent high-temperature thermal and mechanical properties makes the SiC fibers powerful candidate materials for functional applications [6] [7] [8]
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