Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


22480.pdf (13.82 MB)

ETD Abstract Container

Abstract Header

Multiphysics Gas Phase Pyrolysis Synthesis of Carbon Nanotube Yarn and Sheet

Hou, Guangfeng
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491559118937508

Abstract Details

2017, PhD, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Carbon nanotubes (CNTs) have superior properties as a nano-scale object. For real engineering applications, there is a challenge for effectively assembling this nano object into macroscopic entities. Moreover, in the form of macroscale materials, CNT yarn and sheet (CNTYS) have much lower properties than individual nanotubes. CNTYS are composed of billions of micrometer to millimeter length CNT bundles in their cross-sections. Reasons for the underperformance of CNTYS lie mainly in the CNT to CNT junctions in the assemblages, and also the quality, purity, alignment, density and length of the CNTs in the assemblages. CNTYS can be produced continuously using the gas phase pyrolysis (floating catalyst) method, which is a practical method for high rate manufacturing of CNT. This goal of this research is to investigate the process mechanism and develop multiphysics control techniques for the gas phase pyrolysis method to improve the properties of CNTYS. A horizontal reactor has been developed, and CNTYS have been successfully synthesized. The synthesis process integrates multiple physical processes including positive displacement fuel injection, induction pre-heating of the fuel, high temperature synthesis, and electromagnetic and electrostatic excitation to manipulate the nanotubes and plasma in the reactor. These processes are multiscale in time and length. This research investigates both numerically and experimentally some of the complex interrelated factors affecting the multiphysics synthesis process to improve CNTYS properties. A voltage signal was measured inside the reactor, possibly for the first time. The voltage signal was induced by the heater coil and the electromagnetic coil current and creates a cold plasma. Simulation results predicted, for the first time, the existence of a convection vortex in the horizontal gas phase pyrolysis reactor. Based on experimental observations and numerical simulation, a convection vortex model was proposed to describe CNT sock (aerogel or smoke) formation. A web-shell structure was used to study the sock dynamics. Overall, several novel techniques, including induction heating, pressured fuel injection, and electromagnetic and electrostatic manipulation were investigated to improve CNTYS quality and production rate. Ultra-high quality CNT sheet with a Raman G/D ratio of 100 was synthesized. The process yield was improved by controlling the process parameters in the reactor. Discussion of various up and coming technical applications of CNTYS were also included.
Mark Schulz, Ph.D. (Committee Member)
Yijun Liu, Ph.D. (Committee Member)
David Mast, Ph.D. (Committee Member)
Vesselin Shanov, Ph.D. (Committee Member)
Jing Shi, Ph.D. (Committee Member)
222 p.
Mechanical Engineering
carbon nanotube; CNT sock; gas phase pyrolysis; multiphysics

Recommended Citations

Citations

  • Hou, G. (2017). Multiphysics Gas Phase Pyrolysis Synthesis of Carbon Nanotube Yarn and Sheet [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491559118937508

    APA Style (7th edition)

  • Hou, Guangfeng. Multiphysics Gas Phase Pyrolysis Synthesis of Carbon Nanotube Yarn and Sheet. 2017. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491559118937508.

    MLA Style (8th edition)

  • Hou, Guangfeng. "Multiphysics Gas Phase Pyrolysis Synthesis of Carbon Nanotube Yarn and Sheet." Doctoral dissertation, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491559118937508

    Chicago Manual of Style (17th edition)

ucin1491559118937508
504
© 2017, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.