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Multi-Field Physics for the Synthesis of Carbon Nanotube Yarn and Sheet

Su, Ruitao
http://orcid.org/0000-0002-6716-7046
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310862

Abstract Details

2015, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Synthesis of high performance carbon nanotube (CNT) yarn and sheet is a goal for researchers from around the world. A lot of progress has been made in both substrate based and floating catalyst CVD method over past few years. However, no method has produced yarn or sheet that can exceed the properties of carbon fiber materials. Defects reduce the properties of long nanotubes, whereas the short high quality nanotubes are not long enough to produce yarn and sheet with high strength, which limits their practical applications. There is no method to rapidly manufacture cm long high quality nanotubes and form yarn and sheet, and there is a need to more rapidly synthesize nanotubes in the current length ranges of 1-5 mm. The inability to mass-produce at high growth rates and reasonable cost yarn and sheet based on long nanotubes has limited the commercial applications of nanotubes. Compared to the substrate based growth method, the floating catalyst method for CNT synthesis has a larger yield and the cost is lower. The product of floating catalyst method is usually a CNT cylindrical assembly or sock that can be easily spun into yarns and wrapped to form sheets. However, the length of individual carbon nanotube produced by the floating catalyst method ranges from the micro scale to 1-2 mm, which means a relatively weak inter-molecular interaction has limited the CNT yarn’s strength. Impurities and defects are obvious, which affect the yarn and sheet mechanical and electrical properties. New methods are in demand to produce longer and stronger carbon nanotubes at a high rate at low cost. Possible solutions to the above issues are investigated in this thesis. One concept is that multi-field physics (using multiple physical fields to control the synthesis process) may allow the catalyst particles to be stabilized or slowed down in the high temperature growth zone in the floating catalyst method. A longer dwell time for the catalyst particles in the growth zone might increase the length of individual carbon nanotubes. An electromagnetic field is an option for the manipulation of the catalyst particles since Fe nanoparticles are magnetic. For example, a magnetic bottle can be employed to trap charged particles in the reactor while carbon precursors are fed into the reaction zone. The catalyst-CNT assembly can be released and collected when long enough carbon nanotubes are synthesized. With an alternating electromagnetic field, the catalyst particles/nanotubes might be oscillated at a resonant frequency so that the amorphous carbon would be prevented from coating and deactivating the catalyst. During the experiments, a 100 V-60 Hertz AC voltage was measured on the CNT sock assembly. The voltage is believed to come from the electromagnetic induction between the magnetic field generated by the furnace used for the synthesis and the conductive CNT assembly. The voltage indicates the feasibility of magnetic manipulation of the charged particles and sock in the reactor. Moreover, an electrostatic spray system was developed and installed on the reactor to generate better spray patterns and electrically charge catalyst particles, which are expected to be controlled by an electric or magnetic field for purer, straighter and long CNT growth. In addition to physical methods, new chemical recipes play a critical role in high quality CNT synthesis. For example, water and gadolinium salts are being tested for purification and increased CNT length. The concept of multi-field synthesis and initial experimental work to produce the multi-physics reactor are the main contributions of this thesis. This thesis has been an interdisciplinary effort that lays the path for possibly producing high performance carbon nanotube materials using the gas phase pyrolysis method.
Mark Schulz, Ph.D. (Committee Chair)
Weifeng Li, Ph.D. (Committee Member)
David Mast, Ph.D. (Committee Member)
Vesselin Shanov, Ph.D. (Committee Member)
Kumar Vemaganti, Ph.D. (Committee Member)
114 p.
Nanotechnology
carbon nanotube; floating catalyst; magnetic field; electrostatic spray

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Citations

  • Su, R. (2015). Multi-Field Physics for the Synthesis of Carbon Nanotube Yarn and Sheet [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310862

    APA Style (7th edition)

  • Su, Ruitao. Multi-Field Physics for the Synthesis of Carbon Nanotube Yarn and Sheet. 2015. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310862.

    MLA Style (8th edition)

  • Su, Ruitao. "Multi-Field Physics for the Synthesis of Carbon Nanotube Yarn and Sheet." Master's thesis, University of Cincinnati, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310862

    Chicago Manual of Style (17th edition)

ucin1439310862
508
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This open access ETD is published by University of Cincinnati and OhioLINK.