Mechanical property deterioration and defect repair factors of carbon fibers during the continuous growth of carbon nanotubes by chemical vapor deposition

The continuous growth of carbon nanotubes (CNTs) was realized on the surface of moving carbon fiber substrate by chemical vapor deposition (CVD). The changes in the microstructure of the catalyst precursor reduction and the catalyzed growth of CNTs during the continuous process were tracked, and the factors causing the deterioration of mechanical properties and the increase of tensile strength were discussed. The formation of catalyst nanoparticles invaded the surface of carbon fibers, cutting off the continuous graphite layer and causing a loose graphite structure. With the catalyzed growth of CNTs which have good crystallinity, the graphite cross-links between their roots and the fiber surface repaired the defects generated by the catalyst. Due to the repair of surface defects by carbon source decomposition and interface CNTs during CVD process, the tensile strength of CNTs/carbon fiber reinforcement is increased by 8.55% compared with the raw carbon fibers. This research helps to grow CNTs uniformly on the surface of carbon fibers to prepare a large number of composite reinforcements, and can maintain or even improve the overall mechanical properties.