C/C复合材料高温长时烧蚀行为与控制方法

General Science and Technical Report of “Long-time Ablative Behavior of C/C Composites Under High-temperature Conditions and Their Improvement Methods”

利用化学气相渗透法在三维细编穿刺炭毡中的炭纤维表面沉积TaC陶瓷界面,通过控制气体在预制体中的流动方向,获得梯度分布TaC界面改性C/C复合材料。研究了材料的微观结构、弯曲性能以及断裂韧性,结果表明:TaC呈层状分布在炭纤维表面,从C/C复合材料表层到内部,TaC陶瓷相的含量呈梯度分布;梯度分布TaC界面改性C/C复合材料的平均弯曲强度为272.6 MPa,平均断裂韧性为5.0 MPa·m1/2;整体上,沿材料厚度(Z轴)方向,随TaC含量的降低,纤维的拔出长度明显变短;在表层富TaC区,TaC含量对材料断裂行为有较大影响,其表现为:在TaC含量较多的外层,材料断裂为脆性断裂,而在TaC含量较少的内层,材料断裂为假塑性断裂。

TaC ceramic interlayer was deposited on carbon fiber in three-dimensional fine-woven punctured felt by using chemical vapor infiltration method. By controlling the flow direction of the reaction gases in the preform, C/C composites with gradient distributed TaC interlayer were obtained. Microstructure, flexural property and fracture toughness of the as-prepared composites were studied. The results show that TaC interlayer is deposited on the surface of carbon fiber and presents a gradient distribution in C/C composites. The average flexural strength and fracture toughness of the as-prepared composites are 272.6 MPa and 5.0 MPa·m1/2, respectively. In general, with the decreasing of the TaC content along the thickness direction（Z-axis） of the composites,the length of carbon fiber pulled out from the carbon matrix becomes shorter. In TaC-rich area, TaC content has significant influence on fracture behavior of the composites. The fracture behavior of the TaC-rich area is brittle in outer layer which has more TaC, while change to pseudo-ductile in inner layer which has less TaC.