Microstructural transformation impact on mechanical and tribological performance of different temperature heat-treated carbon/carbon composites

• Published in: Ceramics international 2024-10, Vol.50 (19), p.36099-36111
• Main Authors: Gao, Zonglong, Yuan, Zhenyu, Yang, Yu, Li, Zhuan, Huang, Boyun
• Format: Article
• Language: English
• Subjects: Carbon/carbon composites; Mechanical properties; Microstructural evolution; Tribological properties
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2024.06.423

Due to the harsher application environments of C/C composites, optimizing the internal structure of C/C materials through high-temperature treatments (HTT), specifically above 2300 °C, has become an effective method to enhance their properties. The current study investigates the influence of microstructural evolution on the mechanical and tribological behavior of carbon/carbon composites after heat treatments at 2300 °C and 2700 °C. The C/C composites experience a reduction in mechanical properties as the heat treatment temperature is raised. This may be due to the rearrangement of carbon atomic layers at high temperatures, resulting in increased orientation in pyrolytic carbon. However, fibers parallel to the friction surface are relatively less affected, while fibers perpendicular to the friction surface and PyC are more significantly affected. The average coefficient of friction increases from 0.19 to 0.42 as heat treatment temperature from 2300 °C to 2700 °C under the brake pressure of 1 MPa with 25 m/s brake speeds. This phenomenon is attributed to the samples with high graphitization degree (2700 °C) producing a large number of flaky chips under shear stress during friction, which can be easily ground and compacted to form a complete friction film. Additionally, the more easily deformable z-axis fiber asperities increase the contact area, resulting in an increase in the coefficient of friction and friction stability.