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The simultaneous in-situ growth of carbon nanofibers (CNFs) and densification of a CNFs/CF hybrid multiscale felt are accomplished in a single step by thermal gradient chemical vapor infiltration using Fe as the catalyst and vaporized kerosene under atmospheric pressure. A three-dimensional CNF network which could bridge dissimilar components of composites is formed on carbon fibers (CFs). The length of CNFs can reach several micrometers and the diameters are about 80 nm. Smooth and rough surface densified CNFs can be produced after further higher temperature infiltration. CNFs, anchoring to CFs by the adherence of the catalyst nanoparticles, enhance the bonding between CFs and pyrocarbon as well as promoting the formation of a rough laminar pyrocarbon matrix. The deposition mechanisms and physical model are also discussed. This fast catalytic infiltration process can be applied to other ceramic materials and has significant enlargement potential.

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Carbon/carbon (C/C) composites as high temperature structural materials have been widely used in aeronautics and astronautics because of their remarkable mechanical, thermophysical, and tribological properties. For the deep investigation of carbon deposition mechanism, newly developed approaches of fast densification of C/C composites have been indicated, such as thermal gradient chemical vapor infiltration (TCVI), pressure gradient chemical vapor infiltration (PCVI), electrified CVI (ECVI), and chemical liquid‐vaporized infiltration (CLVI). Multilayer coating system provides a new way for the long‐term antioxidation of C/C composites. Carbon nanotubes and nanofibers, forming the bridge between carbon fibers of micrometer size, could also further enhance the mechanical properties of composite materials. Bonded repair of C/C composite structure is used to extend the life of wear or underdesigned components and joins different components at a reasonable cost. All these studies promote the research and development of advanced C/C composites.