Abstract

Carbon nanotube (CNT) wires are light-weight and robust alternatives to conventional metal conductors. The weight savings, increased flexure tolerance, and corrosion resistance of CNT conductors make them a viable solution for a variety of space, defense, and power transmission applications. An individual CNT has orders of magnitude greater electrical conductivity than conventional metal conductors, but this has not been realized in bulk CNT networks. Recently, the use of chemical dopants has resulted in bulk CNT wire conductivities approaching 10 MS/m. As the electrical conductivity of CNT wires continues to approach that of conventional metals, deployment of CNT conductors will require an understanding of how doped CNT conductors behave during practical operation. The initial dissertation research applied radial densification and KAuBr4 chemical doping to commercially available CNT wires resulting in a 6x improvement in electrical conductivity and 67% increase in failure current density. Novel procedures were developed to probe the electrical performance retention as a function of increasing and sustained current application. KAuBr4-densified CNT wires can withstand current densities up to 32 MA/m2 with no degradation in electrical conductivity, exceeding the as-received CNT material’s degradation threshold by greater than 3x. The improved electrical conductivity of KAuBr4-densified CNT wires prevents the onset of Joule heating allowing for the doping benefits to be maintained at increased applied current densities. Further analysis compared the resulting electrical performance retention of three commonly used chemical dopants: I2, IBr, and KAuBr4. The as-received and KAuBr4 doped CNT wires can maintain σRest until near wire failure, while the I2 and IBr doped CNT wires experience degradation at current densities greater than 5 MA/m2. With repeated low current cycling, KAuBr4 was identified as the only dopant able to maintain its initial electrical conductivity over time. Thermal stability analysis determined that I2 and IBr doped CNT wires undergo dopant desorption, while KAuBr4 doped CNT wires result in dopant degradation into other viable dopants, thus maintaining improved electrical conductivity over greater applied current densities. KAuBr4 doped CNT wires have emerged as lightweight conductors capable of retaining their improved electrical properties during long-term, high current applications. Thus, motivating the future adoption of stable KAuBr4 doped CNT wires in a variety of space and defense technologies.

Library of Congress Subject Headings

Carbon nanotubes--Electric properties; Semiconductor doping

Publication Date

7-10-2020

Document Type

Dissertation

Student Type

Graduate

Degree Name

Engineering (Ph.D.)

Department, Program, or Center

Engineering (KGCOE)

Advisor

Brian J. Landi

Advisor/Committee Member

Steven J. Weinstein

Advisor/Committee Member

Ivan Puchades

Campus

RIT – Main Campus

Plan Codes

ENGR-PHD

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