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Design and Development of an Acoustic Levitation System for Use in CVD Growth of Carbon Nanotubes

Qasem, Amal ali
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479809526489146

Abstract Details

2016, MS, University of Cincinnati, Arts and Sciences: Physics.
The most widely used methods for growth of carbon nanotubes (CNTs) arc discharge, laser ablation, and chemical vapor deposition (CVD). Some of these methods have difficulties, such as controlling the quality and straightness of the nanotube in the synthesis of CNTs from substrates. Also, the enhanced plasma chemical vapor deposition method with the catalyst on a substrate produces straighter, larger diameter nanotubes by the tip growth method, but they are short. The difficulty in the floating catalyst method is that the nanotubes stay in the growth furnace for short times limiting growth to about one mm length; this method also leaves many catalyst impurities. One factor that limits CNT growth in these methods is the difficulty of getting enough carbon atoms to the growth catalyst to grow long nanotubes. The motivation of this work is that longer, higher quality nanotubes could be grown by increasing growth time and by increasing carbon atom movement to catalyst. The goal of this project is to use acoustic levitation to assist chemical vapor deposition growth by trapping and vibrating the growing CNTs for better properties. Our levitation system consists of a piezoelectric transducer attached to an aluminum horn and quartz rod extending into the growth furnace. The most important elements of our methods to achieve the acoustic levitation are as follows. 1. Using COMSOL Multi-physic Simulation software to determine the length of quartz rod needed to excite standing waves for levitation in the tube furnace. 2. Determining the resonance frequency of different transducers and horns. 3. Using ultrasound measurement to determine the time of flight, velocity of sound and sound wavelength of different horns. 4. Making Aluminum horns with the appropriate lengths. 5. Using ultrasound measurement to determine the changing of quartz rod velocity of sound and length in the furnace. 6. Mounting the transducer to booster horn and aluminum cylindrical horn above a reflector to produce the standing waves. The levitation of small Styrofoam balls was successful by using this system and verified wavelengths of standing wave and position of levitation. We could not levitate powders, most likely due to electrostatic charging, air currents, but most importantly insufficient power to drive transducer. In addition, we built a CVD growth furnace with ultrasound transducer- horn- quartz rod and reflector. The reflector support also included a sense piezoelectric element for determining standing wave strength. This reflector support was mounted on a linear translation stage to control the quartz rod-reflector separation to produce standing waves. To remove the contaminated unwanted CNTs, we built a separate tube furnace tube filled with a molecular sieve to burn the CNT’s in air. Finally, we made catalyst-coated, ceramic microparticles for levitation and used these to verify CNT growth. Future efforts research would be to levitate these micro particles at room temperature then in the high temperature furnace for growth of carbon nanotubes.
David Mast, Ph.D. (Committee Chair)
Howard Jackson, Ph.D. (Committee Member)
Frank Pinski, Ph.D. (Committee Member)
Hans-Peter Wagner, Ph.D. (Committee Member)
61 p.
Physics
Carbon nanotubes; CVD; Acoustic levitation; Ultrasonics

Recommended Citations

Citations

  • Qasem, A. A. (2016). Design and Development of an Acoustic Levitation System for Use in CVD Growth of Carbon Nanotubes [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479809526489146

    APA Style (7th edition)

  • Qasem, Amal. Design and Development of an Acoustic Levitation System for Use in CVD Growth of Carbon Nanotubes. 2016. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479809526489146.

    MLA Style (8th edition)

  • Qasem, Amal. "Design and Development of an Acoustic Levitation System for Use in CVD Growth of Carbon Nanotubes." Master's thesis, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479809526489146

    Chicago Manual of Style (17th edition)

ucin1479809526489146
854
© 2016, some rights reserved.Creative Commons License Design and Development of an Acoustic Levitation System for Use in CVD Growth of Carbon Nanotubes by Amal ali Qasem is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.