原位生长纳米炭纤维增强C/C复合材料的弯曲破坏过程(英文)

Flexural destructive process of unidirectional carbon/carbon composites reinforced with in situ grown carbon nanofibers

采用催化化学气相沉积法制备原位生长纳米炭纤维(CNFs)改性单向C/C复合材料。通过分析弯曲破坏过程,研究原位生长CNFs对C/C复合材料弯曲性能的影响。结果表明,CNFs的存在明显改变了载荷-位移曲线的线形,在开始的弹性变形阶段出现一个台阶,随后出现类似塑性材料的锯齿状屈服特性曲线。CNF-C/C复合材料的破坏模式由单根纤维的拔出转变为纤维束的断裂。由中织构热解炭(Py C)、CNFs和高织构Py C形成的复杂界面阻碍了裂纹的扩展,改变了裂纹的扩展方向从而导致C/C复合材料具有较高的弯曲强度和模量。

Unidirectional carbon/carbon（C/C） composites modified with in situ grown carbon nanofibers（CNFs） were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of the C/C composites was investigated by detailed analyses of destructive process. The results show that there is a sharp increase in the flexural load-displacement curve in the axial direction of the CNF-C/C composites, followed by a serrated yielding phenomenon similar to the plastic materials. The failure mode of the C/C composites modified with in situ grown CNFs is changed from the pull-out of single fiber to the breaking of fiber bundles. The existence of interfacial layer composed by middle-textured pyrocarbon, CNFs and high-textured pyrocarbon can block the crack propagation and change the propagation direction of the main crack, which leads to the higher flexural strength and modulus of C/C composites.