Effect of aspect ratio on the permittivity of graphite fiber in microwave heating

Jun Fukushima, Shuntaro Tsubaki, Tomoki Matsuzawa, Keiichiro Kashimura, Tomohiko Mitani, Tomoaki Namioka, Satoshi Fujii, Naoki Shinohara, Hirotsugu Takizawa, Yuji Wada

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2 Citations (Scopus)

Abstract

Microwave (MW) heating has received attention as a new heating source for various industrial processes. Some materials are expected to be a more effective absorber ofMW, and graphite is observed as a possible candidate for high-temperature application. We investigated the dependence of the aspect ratio of graphite fibers on both their heating behavior and permittivity under a 2.45 GHz MW electric field. In these experiments, both loss tangent and MW heating behavior indicated that the MW absorption of conductive fibers increases with their aspect ratio. The MW absorption was found to be well accounted for by the application of a spheroidal model for a single fiber. The absorption of graphite fibers decreases with increasing aspect ratio when the long axis of the ellipsoid is perpendicular to the electric field, whereas it increases with the aspect ratio when the long axis is parallel to the electric field. The analytical model indicated that MW heating of the conductive fibers is expected to depend on both the shape and arrangement of the fibers in the electric field.

Original languageEnglish
Article number169
JournalMaterials
Volume11
Issue number1
DOIs
Publication statusPublished - 2018 Jan 22

Keywords

  • Electrical permittivity
  • Graphite
  • Microwave heating
  • Shape effect

ASJC Scopus subject areas

  • Materials Science(all)

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    Fukushima, J., Tsubaki, S., Matsuzawa, T., Kashimura, K., Mitani, T., Namioka, T., Fujii, S., Shinohara, N., Takizawa, H., & Wada, Y. (2018). Effect of aspect ratio on the permittivity of graphite fiber in microwave heating. Materials, 11(1), [169]. https://doi.org/10.3390/ma11010169