SBIR-STTR Award

Nanocomp has demonstrated a continuous fabrication process for SWCNT wires and a batch process for very long SWCNT tapes. Modifications to the conductivity, proposed here, may improve the EM absorption characteristics of these sheets. In this proposal we posit that a CNT wire may be used as a current conductor for both dc and ac frequencies under a wide variety of conditions. Some preliminary data on the electrical characteristics of the wire are presented. We note that at ambient temperature the electrical resistivity is about 1 x 10-4 ohm-cm (1x106 S.m-1) at a wire density of about 0.2 g/cc which on weight basis is close to that of industrial copper (58.6 x 106 S.m-1) whose density of 8.96 g/cc. At high frequencies (>2 GHz) the nanotube wire becomes very much more effective than copper thereby saving considerable weight. At frequencies less than 50 MHz, a power savings for the same capacity can be achieved only if the nanotube conductivity is increased[1]. Widespread commercial applications of CNT wires requires improved conductivity. Means of accomplishing this include doping during or after synthesis, and a novel means of Chirality control implemented during synthesis.

Keywords:
Swcnt Carbon Nanotubes, Conductors, Em Absorption, Chirality Control, Boron-Doping, Fatigue, Resistivity, Conductivity

Nanocomp has demonstrated an extraordinary increase in conductivity of continuous carbon nanotube wires to over 2 x 10^6 S/m. In addition we have demonstrated fabrication of more than a kilometer of 3 tex SWCNT CNT wire per day. Ribbon conductors made also been developed from 3 foot by 6 foot SWCNT or DWCNT sheets. These sheets are in daily production at a readiness level over 4 in automated equipment. We have developed as part of the Phase I program a means of insulation capable of temperatures over 300 ºC for a short period of time. Further we have developed a connector system that should enable direct attachment to standard mil specification connectors. Strength of the SWCNT wire is now 1.5 GPa continuously and is soon expected to exceed 3 GPa continuously. A path to increase conductivity to near that of copper is being explored. Safety issues both in manufacturing and for the consumer were also addressed and significantly only iron catalysts are allowed in our process, thereby eliminating carcinogenic nickel or cobalt from the environment.

Benefit:
The dramatic increase in electrical conductivity, reduction in weight, improvement in corrosion performance and performance at higher frequencies resulting from our Phase I study, have resulted a number of real Air Force Applications for this new type of CNT wire. Performance improvements in a wide variety of space and aerospace and even Navy applications are being explored; in addition applications in cell phones, photocopiers are being developed for the commercial market in collaboration with private companies.

Keywords:
Swcnt Carbon Nanotubes, Conductors, Em Absorption, Chirality Control, Boron-Doping, Fatigue, Resistivity, Conductivity