Tailoring Carbon Fiber/Carbon Nanotubes Interface to Optimize Mechanical Properties of C f ‐ CNT s/ S i C Composites

C f /SiC composites were fabricated using fiber coatings including CNT s and matrix infiltration using the polymer impregnation and pyrolysis process. Interface between fiber and CNT s ( CF / CNT s) was tailored to optimize mechanical properties of hybrid composites. The tailored interphases, such as P yrocarbon ( P y C ) and P y C / S i C , protect fibers from degradation during the growth of CNT s successfully. Hybrid composites with well‐tailored CF / CNT s interface displayed significantly increased mechanical strength (352 ± 21 MP a) compared with that (34 ± 3 MP a) of composites reinforced with CNT s, which grown on carbon fibers directly. The interfacial bonding strength of hybrid composites was improved and optimized by tailoring the CF / CNT s interface. Interfacial failure modes were studied, and a firm interface bonding at the joint where CNT s grown was observed.