碳源组成对化学气相渗透C/C复合材料致密化及热解炭结构的影响

为分析碳源在化学气相渗透过程中的沉积机制，以碳纤维针刺整体毡为预制体，添加丙烯（C₃H₆）的天然气混合气体为碳源，研究了碳源组成对C/C复合材料致密化及热解炭结构的影响。结果表明:相比于以天然气为碳源，以添加了适当比例C₃H₆的天然气为碳源，可有效提高C/C复合材料的致密化速率及密度分布均匀性；同时，有利于生成高织构的热解炭。最优条件（9vol% C₃H₆）下沉积100 h后，C/C复合材料的密度和径向密度偏差分别为1.40 g/cm3和0.04 g/cm3，热解炭为均一的粗糙层结构，石墨化度高；而以天然气作碳源时，密度和径向密度偏差分别为1.17 g/cm3和0.07 g/cm3，热解炭为二元带状结构，石墨化度较低；当C₃H₆比例增加到17vol%时，其密度和径向密度偏差分别为1.28 g/cm3和0.10 g/cm3，密度及密度分布均匀性较最优条件下制备的复合材料明显降低。 

Effects of carbon source composition on densification of C/C composites and microstructure of pyrolytic carbon derived from chemical vapor infiltration

In order to analyze the deposition mechanism of carbon source during the chemical vapor infiltration process, using carbon fiber neddled flet as preform, propylene (C₃H₆) added natural gas mixture gas as carbon source, the effects of carbon source composition on densification of C/C composites and microstructure of pyrolytic carbon were investigated. The results show that compared with using natural gas as carbon source, using a moderate ratio of C₃H₆ added natural gas as carbon source can improve the densification efficiency and density distribution uniformity of C/C composites effectively. At the same time, it is beneficial to form high texture pyrolytic carbon. After deposition for 100 h under the optimal condition (9vol% C₃H₆), the density and density deviation at radial direction of C/C composites are 1.40 g/cm³ and 0.04 g/cm³ respectively, the pyrolytic carbon is homogeneous rough laminar structure, and the graphitization degree is high. While when using natural gas as carbon source, the density and density deviation at radial direction are 1.17 g/cm³ and 0.07 g/cm³ respectively, the pyrolytic carbon is binary banded structure, and the graphitization degree is lower. When the ratio of C₃H₆ is improved to 17vol%, the density and density deviation at radial direction of it are 1.28 g/cm³ and 0.10 g/cm³ respectively. Compared to the composite prepared under the optimal condition, the density and density distribution uniformity decrease obviously.