Effects of micro-carbon particles and nano-carbon dots induced structural and mechanical changes of C/C composites prepared by directional pulsed gas flow TG-CVI method

• Published in: Diamond and related materials 2020-05, Vol.105, p.107759, Article 107759
• Main Authors: Zhang, Sheng, Ji, Genshun, Xia, Tingxi, Jia, Jiangang, Zhen, Menghan, Li, Zhou, Hao, Xiangzhong
• Format: Article
• Language: English
• Subjects: Carbon; Carbon dots; Carbon/carbon composites; Composite materials; Crystallization; Directional pulsed gas flow TG-CVI; Flexural strength; Fracture toughness; Gas flow; Graphitization; Microscopy; Microstructure; Morphology; Optical microscopy; Polarized light; Preforms; Pseudoplasticity; Pyrolysis
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2020.107759

Commercial carbon felt preforms modified by micro‑carbon particles and nano‑carbon dots were used to fabricate C/C composites by directional pulsed gas flow TG-CVI method. Microstructure, fracture morphology, phase constitution and degree of crystallization of the composites were characterized by polarized light microscopy (PLM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Laser confocal Raman microscopy (RMS), respectively. Flexural strength and fracture toughness of the composites was tested by universal electronic testing machine. Results showed that the pyrolysis carbon structure of C/C composites changed from smooth layer to rough layer after the preform was modified by the carbon dots or particles. The degree of graphitization increased from 2.33% of Cf-0/C to 22.09% of Cf-0.05/C; the corresponding fracture mode changed from brittle fracture to pseudo-plastic fracture, and flexural strength slightly decreased. Commercial carbon felt preforms modified by micro-carbon particles and nano-carbon dots were used for preparation of C/C composites by directional pulsed gas flow TG-CVI method. Results showed that the pyrolysis carbon (PyC) structure of the C/C composites changed from smooth layer to rough layer after the preform was modified. The fracture toughness was increased and the flexural strength was slightly decreased. [Display omitted] •Introduction of carbon particles or dots influences the texture of C/C composites.•CDs modified C/C composites has a RL structure and high degree of graphitization.•The CDs induced high-texture PyC deposition mechanism was investigated.