NEW GENERATION OF CARBON-CARBON COMPOSITES WITH CARBON NANOTUBES

摘要

Two classes of carbon nanotubes (pure carbon and nitrogen doped) were in-situ grown within a carbon fibre cloth matrix in order to develop a new generation of carbon-carbon (C-C) composites. Such three-dimensional carbon-carbon composites are expected to retain the stability of the carbon fibre cloth whilst gaining addition electrical, thermal and mechanical properties from the carbon nanotubes. Carbon nanotubes have been grown in the voids between the carbon fibres in the cloth at 760 °C using solution of ferrocene in toluene as a source of iron catalyst and carbon. Carbon nanotubes were not attached to the carbon fibre surface but enclosed inside these voids. Furthermore we used a so-called monochiral process to synthesise highly crystalline nitrogen doped nanotubes. In this case pyrazine was added to the ferrocene/toluene solution while maintaining the rest of the conditions. As nanotubes were grown between the carbon fibres intriguing octopus-like structures were grown from the same central catalyst particles. The presence of nitrogen within the nitrogen-doped nanotubes is expected to improve particularly the electrical conductivity of the C-C composite but also the mechanical properties due to the higher packing density of the nanotubes and the N-N interaction between the nanotubes.