The influence of additive content on microstructure and mechanical properties on the Csf/SiC composites after annealed treatment

- The addition of the chopped carbon fiber improved fracture toughness of the Ccf/SiC composites.
- The appropriate proportion of La2O3 and Al2O3 would improve the wettability of SiC grains.
- The in situ SiC nanowire after annealed treatment increased the mechanical properties.
- Whisker pullout and nanowire bridge were the main toughened mechanics for Ccf/SiC composites.

In this paper, micrometers long and 20-100 nm diameter SiC nanowires had been synthesized in the short cut fiber toughened SiC composites (Csf/SiC) by annealing treatment. The present work demonstrated that it was possible to fabricate the in situ SiC nanowires toughened Csf/SiC composites by annealed treatment. The “vapor-liquid-solid” growth mechanism of the SiC nanowires was proposed. The mainly toughened mechanism concluded grain bridging, crack deflection, fiber debonding and SiC nanowires, which can improve fracture toughness.