Material processing in electric and magnetic fields at microwave frequencies in a single mode cavity

Dinesh Kumar Agrawal, Rustum Roy, R. Peelamedu, Jiping Cheng, Y. Fang

Research output: Contribution to journalConference article

Abstract

Microwave technology has been applied successfully to many areas including polymers, ceramics, composites, and metallic materials. It has many advantages over the conventional methods such as rapid volumetric heating leading to fine microstructures and improved mechanical properties. Dramatic enhancements in reaction and material diffusion kinetics during sintering have been observed by many researchers. The cause of these effects has been attributed to, but not very well understood, the so-called 'non-thermal or microwave effects'. Thus far almost 100% work on microwave processing of materials has been confined to using a multi-mode cavities in which electric and magnetic fields cannot be distinguished. Using a 2.45 GHz, single mode cavity, it is possible to separate electric and magnetic components of microwave radiation and expose small size samples to mostly pure E and H fields. In this presentation we report the effect of electric and magnetic fields at 2.45 GHz frequency on the heating behavior of variety of materials. The survey of variety of samples of metals, ceramics, composites and magnetic materials showed remarkable differences in their heating behaviors and microstructural developments. It was observed that ferrites, dielectric insulators such as BaTiO3 or TiO2, could be rendered non-crystalline (amorphous) in 5-30 seconds, without even melting, when processed in 2.45 GHz single mode cavity, at the magnetic node alone. The magnetic properties of these commercial materials can be controlled by exposure to these fields. Even Silicon metal also showed decrystallization but in E-field. The results establish conclusively that the magnetic field interaction causes variety of losses and dominates the heating of almost all materials and often produces unexpected results.

Original languageEnglish (US)
Article number6C3-4
Number of pages1
JournalIEEE International Conference on Plasma Science
StatePublished - Dec 1 2004
EventIEEE Conference Record - Abstracts: The 31st IEEE International Conference on Plasma Science, ICOPS2004 - Baltimore, MD, United States
Duration: Jun 28 2004Jul 1 2004

Fingerprint

Microwave frequencies
microwave frequencies
Electric fields
Magnetic fields
microwaves
cavities
heating
electric fields
Processing
Microwaves
magnetic fields
Heating
ceramics
composite materials
causes
magnetic materials
metals
ferrites
sintering
Ferrites

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

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title = "Material processing in electric and magnetic fields at microwave frequencies in a single mode cavity",
abstract = "Microwave technology has been applied successfully to many areas including polymers, ceramics, composites, and metallic materials. It has many advantages over the conventional methods such as rapid volumetric heating leading to fine microstructures and improved mechanical properties. Dramatic enhancements in reaction and material diffusion kinetics during sintering have been observed by many researchers. The cause of these effects has been attributed to, but not very well understood, the so-called 'non-thermal or microwave effects'. Thus far almost 100{\%} work on microwave processing of materials has been confined to using a multi-mode cavities in which electric and magnetic fields cannot be distinguished. Using a 2.45 GHz, single mode cavity, it is possible to separate electric and magnetic components of microwave radiation and expose small size samples to mostly pure E and H fields. In this presentation we report the effect of electric and magnetic fields at 2.45 GHz frequency on the heating behavior of variety of materials. The survey of variety of samples of metals, ceramics, composites and magnetic materials showed remarkable differences in their heating behaviors and microstructural developments. It was observed that ferrites, dielectric insulators such as BaTiO3 or TiO2, could be rendered non-crystalline (amorphous) in 5-30 seconds, without even melting, when processed in 2.45 GHz single mode cavity, at the magnetic node alone. The magnetic properties of these commercial materials can be controlled by exposure to these fields. Even Silicon metal also showed decrystallization but in E-field. The results establish conclusively that the magnetic field interaction causes variety of losses and dominates the heating of almost all materials and often produces unexpected results.",
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Material processing in electric and magnetic fields at microwave frequencies in a single mode cavity. / Agrawal, Dinesh Kumar; Roy, Rustum; Peelamedu, R.; Cheng, Jiping; Fang, Y.

In: IEEE International Conference on Plasma Science, 01.12.2004.

Research output: Contribution to journalConference article

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AU - Agrawal, Dinesh Kumar

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AU - Peelamedu, R.

AU - Cheng, Jiping

AU - Fang, Y.

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