Flexural destructive process of unidirectional carbon/carbon composites reinforced with in situ grown carbon nanofibers
(1. Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
3. Key Laboratory of Ministry of Education for Conveyance and Equipment, College of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang 330013, China)
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
3. Key Laboratory of Ministry of Education for Conveyance and Equipment, College of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang 330013, China)
Abstract: 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.
Key words: carbon nanofiber; C/C composites; flexural destruction; crack propagation