Effect of CNT orientation on the mechanical property and fracture mechanism of vertically aligned carbon nanotube/carbon composites

Abstract

The effect of carbon nanotube (CNT) orientation on the mechanical properties and fracture mechanisms of a vertically aligned CNT/C composite was studied in this work by a combination of nanoindentation and micropillar compression techniques. The results suggest stronger response of the composite when loading parallel to the CNT orientation. This led to higher Young's modulus and hardness (≈34 GPa and ≈3.75 GPa) at this direction than those at perpendicular direction (≈19 GPa and ≈2.6 GPa). The mechanical anisotropy led to fracture mechanisms that were also dependent on the CNT orientation. At 0° direction, the composite was fractured into segments by splitting of the micropillar. While at 90° direction, the composite was much brittle and was fractured by dual shearing, implying a strong CNT/C interface.