Microstructure and flexural properties of C/C-Cu composites strengthened with in-situ grown carbon nanotubes.

Carbon nanotubes (CNTs) reinforced carbon/carbon-copper (C/C-Cu-CNTs) composites were fabricated by thermal gradient chemical vapor infiltration (TGCVI). The effect of copper and CNTs on the microstructure and flexural properties of carbon/carbon (C/C) composites were investigated. Results showed that the flexural strength of C/C-Cu-CNTs composites was larger than that of pure C/C composites and C/C-Cu composites. Copper particles coated on carbon fibers reduced the contact area between pyrolytic carbon matrix and carbon fibers, leading to the decrease of flexural strength by 17.34% in direction Z and 22.44% in direction X, respectively. However, CNTs catalyzed by copper particles linked adjacent pyrolytic carbon layers together as a bridge and made propagation resistance of cracks increased, which strengthened the matrix. The flexural strength of C/C composites was improved by 33.61% in direction Z and 23.94% in direction X, respectively. [ABSTRACT FROM AUTHOR]