Gas-phase Synthesis of Carbon Nanostructures and Composites

CVD synthesis of carbon nanotubes was carried out using ethanol paralysis in tubular quartz reactor at atmospheric pressure of hydrogen. Ni, Co and Fe catalyst were used for CNT deposition. The CNT samples obtained under various experimental conditions were studied by scanning electron microscopy (SEM), X-ray fluorescent microanalysis and Raman spectroscopy. The ratio of ID/IG of D (~1360 cm -1 ) and G (~1580 cm -1 ) Raman peaks was monitored to estimate the crystalline of graphite-like material. The optimal conditions for synthesis of CNTs on the Si-substrates and on the SiO2-based fiberglass were determined. MWNT were produced with 25-30 nm diameters, up to 30 microns in length and with crystallite size La from 2.7 nm to 7 nm. DC electrical properties of carbon composites MWNT/SiO2-fiberglass were examined. Specific resistance was about 10 cm and more depending on CNT content. It was found that the resistivity of the carbon composites MWNT/SiO2 is sensitive to external pressure. Processing of composite with binding polymer significantly improves stability and repeatability of its voltage-current characteristics.