Models Proposed to Explain the Electrical Conductivity of Polymer-Derived Silicon Carbide Fibers

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• 作者：Tianjiao Hu ; Xiaodong Li ; Wenjing Pu ; Zengyong Chu ; Gongyi Li and Qinghua Wang
• 刊名：Journal of the American Ceramic Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：100
• 期：1
• 页码：167-175
• 全文大小：1460K
• ISSN：1551-2916

文摘

Two types of silicon carbide fibers (SiC_f) 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 SiC_f obtained by direct pyrolysis, whereas a free carbon phase determined the conductivity of the SiC_f 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 SiC_f. Quantitative analysis based on these models indicated an electrical resistivity of ~10⁻² Ω·cm for the carbon layer on the surface of SiC_f obtained by direct pyrolysis. The electrical resistivity and the percolation threshold of the free carbon in SiC_f prepared by the preheated pyrolysis method were 10⁻¹ Ω·cm and 11.3% respectively.