难熔化合物掺杂C/C复合材料的裂纹扩展及断裂模式分析

利用场发射扫描电镜对难熔化合物掺杂C／C复合材料进行了原位三点弯曲测试，在线观测了裂纹的扩展模式和缺陷的演化规律，并结合OM、SEM和TEM所表征的微观结构，揭示了材料的断裂机理。结果表明：难熔化合物掺杂C／C复合材料的断裂以“弱界面断裂”为主，裂纹优先在基体碳、碳布层间及纤维束搭接处等薄弱环节中产生，成为材料的初始破坏面，随着载荷的增加，裂纹沿着薄弱界面进行扩展，形成贯穿性的大裂纹，并导致材料最终失效。

Crack Propagation and Fracture Modes Analysis of Refractory Compound Doped C/C Composites

In this paper, the evolution of interior defeats and crack extension of refractory compound carbon/carbon composites are investigated by in situ SEM flexural testing. The fracture modes are also discussed according to OM, SEM and TEM analysis. Results show that the fracture of refractory compound carbon/carbon composites is weak -interface fracture. Cracks take place preferentially at the interface between carbon cloths or between long bundled fibers and web shot-cut fibers, which turn into the initial fracture face. With increasing the loading, cracks propagate along the weak interface. Finally the cracks propagation through all the composites and these materials rupture.