Nanotube deposition in a continuous arc reactor for varying arc gap and substrate temperature

A new continuous method for producing mounted carbon nanotubes (CNT) has been developed using the arc discharge method, in which a woven carbon substrate is used as a carbon source. In the process, carbon nanotubes grow on the fibres of the carbon substrate during the arc discharge. The method used differs from the conventional arc discharge method in that it deposits on the anode using low current (less than 20 A), with inter-electrode gaps of more than 5 mm and is run at atmospheric pressure, so that the substrate can be continuously fed and recovered. The aim of this work was to study the effect of the physical parameters of the arc on substrate surface temperature and on the CNT growth there. The effects of arc gap and buffer gas flow through the anodic substrate were investigated. An optical pyrometric technique was used to determine the substrate surface temperature. It was found that carbon nanotube growth was favoured over the temperature range 3600-3700 50 K and not favoured at higher temperatures of 3800-4000 50 K. This indicates that CNT growth is unlikely to be due to vaporization/condensation of small molecular carbon species. (c) 2005 Elsevier B.V. All rights reserved.