通过烧成制备了电阻率量级大小不同的三种连续SiC纤维, 对纤维的元素组成、结晶性能和表面结构进行了分析. 结果表明: 通过调整不熔化及烧成工艺参数可以获得电阻率量级不同的连续SiC纤维. 当纤维表层具有一定厚度的高富碳层结构时, 纤维的电阻率受整体自由碳含量与结晶性能的影响不再显著, 此时, 纤维将具有较低的电阻率. 富碳层的产生与不熔化纤维烧成时分解产生的烃类小分子的重新裂解沉积有关. 通过低温氧化除去纤维表面的富碳层可以使纤维电阻率增大. 表面结构对连续SiC纤维的电阻率大小有重要影响.
Three kinds of continuous SiC fibers with different specific resistivity were prepared by the pyrolysis of cured polycarbosilane fiber, and the structure and composition of the three fibers were characterized. Results show that SiC fibers with different specific resistivity can be obtained by changing the curing and pyrolysis conditions. And the total free carbon content and the ability to crystallize will no longer affect the specific resistivity notably when the fiber is covered with an excess carbon layer, as a result the fiber will have a low electrical resistivity. The excess carbon layer in the circular outer part is originated form the re-pyrolysis and deposition of hydrocarbon volatiles. Removal of the carbon by oxidative treatment may affect the surface property and also promote the magnitude of specific resistivity. The influence of the surface property on the specific resistivity is considerable which should not be neglected.
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