Fabrication and mechanical properties of carbon fibers/lithium aluminosilicate ceramic matrix composites reinforced by in-situ growth SiC nanowires

To improve the mechanical properties of carbon fibers/lithium aluminosilicate (C-f/LAS) composites, C-f/LAS with in-situ grown SiC nanowires (SiCnw-C-f/LAS) were prepared by chemical vapor phase reaction, precursor impregnation, and hot press sintering, consecutively. The effect of multi-scaled reinforcements (micro-scaled C-f and nano-scaled SiCnw) on the mechanical properties was investigated. The phase composition, microstructure and fracture surface of the composites were characterized by XRD, Raman Spectrum, SEM, and TEM. The morphology of SiCnw has a close relation with the content of Si. Microstructure analysis suggests that the growth of SiC nanowires depends on the VLS mechanism. The multi-scale reinforcement formed by C-f and SiCnw can significantly improve the mechanical properties of C-f/LAS. The bending strength of SiCnw-C-f/LAS reaches to 597 MPa, achieving an increase of 19% to C-f/LAS. Moreover, the samples show a maximum fracture toughness of 11.01 MPa m(1/2), achieving an increase of 46.4% to C-f/LAS. Through analysis of the fracture surface, the improved mechanical properties could be attributed to the multi-scaled reinforcements by the pull-out and de-bonding of C-f and SiCnw from the composites.