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Design, Fabrication and Testing of Novel Coils Aimed at Increasing the Free Surface Area of Levitated Samples in Electromagnetic Levitation Melting

Youssefian, Mohammad Reza | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54756 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Halali, Mohammad
  7. Abstract:
  8. Condensation from a gaseous phase is a common method for the fabrication of metallic nanoparticles. Electromagnetic induction furnaces are the most common equipment used for this method. Since the sample doesn’t touch any foreign object, this method is one of very few ways to synthesize ultrapure nanoparticles. However, a major setback of this method is its low production rate.One of the only workarounds to this issue is to increase the melt’s surface area so as to present a larger surface for evaporation. In the common setup for this furnace the molten sample takes on a spherical shape which unfortunately holds the lowest surface to volume ration of any shape. The endeavor in this study has been to attain non-spherical shapes for the levitated melt in order to increase its surface area to mass ratio.The copper coils commonly used to levitate the samples are one of the only parameters that affect the melt’s shape. Therefore, this study was aligned towards the alteration and optimization of this functional part to achieve a non-spherical melt shape. In all previous by other groups, the copper coils have had the common property of axial symmetry. Herein, focusing on the goal of attaining an increased total mass and surface area to mass ratio for the levitated melt used in nanoparticle synthesis; novel coils breaking the common norm of axial symmetry have been designed, fabricated and tested.Benefiting from the novel design of these pioneer coils, never-before-available shapes for samples were successfully levitated. The most effective sample shape to achieve the highest final surface area to mass ratio was recognized to be the “pipe” shape, resulting in an increase of up to %180 surface area of the sample in its solid state and up to 28% increase in surface area for the molten levitated droplet
  9. Keywords:
  10. Electromagnetic Levitation ; Parameters Optimization ; Production Rate Increase ; Surface Area to Mass Ratio ; Coil Design

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