Abstract: High performance SiC(f)/SiC composites were fabricated by chemical vapor infiltration (CVI) processing. The effects of pre-coating of SiC fiber on the mechanical properties
and microstructures of SiC(f)/SiC composites were investigated. It was found that the introduction of C or BN pre-coating on SiC fiber surface could promote the pull-out
of fiber and interfacial debonding in the course of fracture markedly, coupled by great increases of fracture toughness and work of fracture. SEM micrographs indicated
that strong interfacial bonding between fiber and matrix was changed, suggesting that the brittle fracture mode of SiC(f)/SiC composite without any pre-coating was
improved. HREM observation showed that in the initial period of CVI processing, graphite interphase with obvious layered configuration with better crystallization degree was first deposited
on the surface of fiber, whereas the C pre-coating on SiC fiber was amorphous.

Key words: SiC(f)/SiC, composites, mechanical properties, interfacial structure