晶须对碳碳复合材料组织和力学性能的影响

添加硅灰石(CaO·SiO₂)晶须制备碳纤维预制体, 并在980 ℃下进行化学气相沉积, 高温石墨化处理后制备得到CaO·SiO₂晶须改性的C/C复合材料。利用SEM、金相显微偏光分析以及力学实验等方法研究了预制体结构对基体微观结构、物理性能和力学性能的影响。实验结果表明: 添加CaO·SiO₂晶须会诱导热解炭呈锥形生长, 同时在石墨化过程中会诱导热解炭的组织结构发生有序性转变, 与基体反应生成SiC二次纤维。添加CaO·SiO₂晶须使得复合材料的石墨化度由31.6%提升至41.1%, 导热和导电性能相比于未添加晶须时分别增加了71.7%和14.3%, 复合材料的弯曲强度相比于未添加晶须时提升了5%。

Effect of Whiskers on the Microstructure and Mechanical Properties of Carbon-Carbon Composites

Carbon fiber preforms were prepared by adding wollastonite (CaO·SiO₂) whiskers, and processed by chemical vapor deposition was performed at 980 ℃. After high-temperature graphitization, carbon-carbon composites modified by using CaO·SiO₂ whisker were prepared. The effects of preform structure on the microstructure, physical properties and mechanical properties of the matrix were studied by using SEM, metallographic analysis with the polarized light microscopy, as well as mechanical experiments. The experimental results show that the addition of CaO·SiO₂ whiskers can induce pyrolytic carbon to grow in a cone shape. Meanwhile, the graphitization process can induce an orderly transformation in the structure of pyrolytic carbon, which leads to the reaction between pyrolytic carbon and the matrix, generating SiC secondary fibers. The addition of CaO·SiO₂ whiskers can result in the graphitization degree of the composite increased from 31.6% to 41.1%, and the thermal and electrical properties improved by 71.7% and 14.3%, respectively, as well as the flexural strength of the composites increased by 5% compared to those without the addition of whiskers.