A report presents additional information about the process reported in "Manufacturing High-Quality Carbon Nanotubes at Lower Cost"; (GSC-14601) NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 62. To recapitulate: High-quality batches of carbon nanotubes are produced at relatively low cost in a modified atmospheric-pressure electric-arc welding process that does not include the use of metal catalysts. What would normally be a welding rod and a weldment are replaced by an amorphous carbon anode rod and a wider, hollow graphite cathode rod. Both electrodes are water-cooled. The cathode is immersed in ice water to about 0.5 cm from the surface. The system is shielded from air by flowing helium during arcing. As the anode is consumed during arcing at 20 to 25 A, it is lowered to maintain it at an approximately constant distance above the cathode. The process causes carbon nanotubes to form on the lowest 5 cm of the anode. The arcing process is continued until the anode has been lowered to a specified height. The nanotube-containing material is then harvested. The additional information contained in the instant report consists mostly of illustrations of carbon nanotubes and a schematic diagram of the arc-welding setup, as modified for the production of carbon nanotubes.

This work was done by Jeanette M. Benavides and Henning Leidecker ofGoddard Space Flight Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Materials category.This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel, Goddard Space Flight Center; (301) 286-7351.

Refer to GSC-14435.

NASA Tech Briefs Magazine

This article first appeared in the July, 2005 issue of NASA Tech Briefs Magazine.

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