Mechanical enhancement of lightweight ZrB2-modified carbon-bonded carbon fiber composites with self-grown carbon nanotubes

Carbon-bonded carbon fiber (CBCF) composites consist of chopped carbon fibers network by vitreous carbon at the intersections with high porosity, low thermal conductivity and high-temperature resistance. To further enhance mechanical properties of CBCF composites, nanostructured modification can inspire the creation of CBCF composites with tunable mechanical properties. Here, we report an self-grown strategy to prepare carbon nanotubes (CNTs) and ZrB2-modified CBCF composites with a green and single-step process without any foreign gases. The CNTs-ZrB2 was directly self-grown in CBCF matrix from zirconium (Zr) and boron (B)-contained polymeric precursors during thermal pyrolysis. Results showed that the CNTs are uniformly dispersed in the composites with several hundred micrometers length. The CNTs play a significant role on improving mechanical properties of CBCF composites by pulling-out and bridging effect compared with CBCF composites without CNTs.