Significant improvement of mechanical properties of carbon/carbon composites by in situ growth of SiC nanowires

In order to improve the mechanical properties of carbon/carbon (C/C) composites, homogeneous and uniform SiC nanowires were in situ grown in low-density 2.5D C/C preform using precursor infiltration pyrolysis method with ferrocene as catalyst. SiC nanowire reinforced C/C composites were obtained via chemical vapor infiltration. The linear nanowires consisted of single crystal β-phase SiC with uniform morphology of about 200 nm in diameter and 100 µm in length. Due to the effect of SiC nanowires, the size of pyrolytic carbon (PyC) grain greatly refined in the process of densification. After introducing SiC nanowires, the flexural and shear strength of the composites increased by 131% and 68%. The strength improvement was attributed to the improvement in the bonding of the fibers/PyC interface, the nanoparticles' dispersion strengthening effect and the increased energy absorption due to the deflection of cracks, the pullout of SiC nanowires and the break of SiC/PyC microrods.