Improving flexural performance of repaired C/C composites through Ti addition: Mechanism analysis

Ti-doped Ni-based solder was used as the repair agent to recover the flexural performance of the damaged carbon/carbon (C/C) composites. The effects of the contents of Ti on the microstructure, chemical compositions, and flexural strength were investigated. The thermal stress distribution and repair mechanism was studied by finite element analysis methods. The addition of an appropriate amount of Ti enhanced the wetting performance of the repair agent on the surface of C/C composites. Besides, the TiC hard particles formed at the interface provided strengthen effect, and form a gradient structure of coefficient of thermal expansion (CTE), thereby enhancing the interface bonding ability and improving the flexural performance of the repaired C/C composites. The flexural strength was the highest with a recovery rate of 92.6 % when the content of Ti was 5 wt%. This work provides a strategy for the engineering application and improving the damage repair of C/C composites.