Synthesis of Carbon Nanotubes and Silicon Carbide Nanofibers as Composite Reinforcing Materials

Abstract

The excellent mechanical properties ofnanomaterials are driving research into the creation of strong and tough nanocomposite systems and new forms ofnanomaterials. It is critical to select an appropriate reinforcing material with desired microstructures and properties to achieve better nanocomposite performance. The present study focused on synthesis and processing-microstructure relationships of multiwalled carbon nanotubes (CNTs) and SiC nanofibers with chemical vapor deposition (CVD). Various CNTs grown by CVD with anodic aluminum oxide (AAO) templates were examined with scanning and transmission electron microscope (SEM and TEM). It was demonstrated that the experimental conditions, especially catalysts and plasma, have significant impact on CNT growth rates and microstructures. Both catalyst and plasma can increase the deposition rate about one order of magnitude. In addition, catalysts promote the secondary growth of CNTs inside the primary CNTs and plasma may improve the stiffness of primary and secondary CNTs. The SiC nanofibers grown by CVD with catalysts were also investigated. SiC diameters match well with the diameters of precursor CNTs. indicating SiC nanofiber size is controlled by the catalysts originated from CNTs. Generally, CNTs fabricated with CVD-template method have disordered graphitic structures and thus have lower tensile strength, but the disordered structures may help for the load transfer between graphitic layers. In the present study, CVD-SiC nanofibers appear to be stiffer than multiwalled CNTs and may also serve as a good candidate for composite reinforcing materials.