Interfacial characteristic and reinforcement mechanism of the carbon nanotube/zinc composite

The carbon nanotube (CNT)/zinc composite film was prepared by the composite electrodeposition. It is remarkable that the zinc deposit on the surface of CNTs is very smooth and continuous, and no apparent interfacial defect is observed. In contrast to the currently known CNT/metal composites, such distinguished interfacial feature is rare. The SEM observation illustrates that, while the films deform, the optimum interface coupling permits debonding and sliding of the CNTs within the matrix. CNTs are pulled out of the matrix in the wake and stretched between crack faces. Although the debonding and sliding of CNTs in the matrix would weaken the interfacial cohesion, the residual sliding friction at the interface still contributes to the load transfer. When the crack grew wider, CNTs begin to deform and fracture completely. Moreover, the bridging nanotubes tend to align perpendicular to the crack direction, and these high strength tubes shear the matrix while they shift inside the composite. All these behaviors consume energy and contribute to the reinforcement. The average Vickers hardness of the CNT/zinc coating increased progressively from HV178.3 to HV493.5.