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Project 6

"Modeling of microwave sintering and absorption mechanisms in ceramic and metallic powders"

EST Project MEST-CT-2005-020986

Fellow Photo of Tomasz Jakub Galek

 M.Sc. Tomasz Jakub Galek
Foreseen duration 34 months
Start Date 01.12.2006
End Date 30.09.2009
Ministering Institut Institute of General Electrical Engineering, University of Rostock
Project Images and Movies

 
Figure 1
The effective electric permittivity and magnetic permeability for metallic-dielectric mixtures are extracted
from electromagnetic full 3D simulation data in the microwave range. Computer simulations are performed
with a cutting-edge electromagnetic simulation software, CST Microwave Studio® 2008 (CST MWS).
The model of metallic powder consists of periodically arranged spherical particles in a cubic close packed
(CCP) structure. Arrows show the polarization of the magnetic (H) and electric field (E), and the direction
of propagation. In this example, the model structure contains 3 unit cells of copper particles arranged in
CCP structure.

 

 
Figure 2
The extraction of the effective permittivity and permeability of the powder, allows us to switch from
micro scale simulations to macro scale simulations. The figure shows a microwave oven with a cylindrical
sample on supporting glass plate. Macro scale coupled simulations of microwave propagation inside the
oven and the heating of the sample can lead to optimization of industrial sintering processes as well as
to rapid prototyping of new designs and materials.

 

 
Movie 3
An example structure of periodically arranged copper particles. Arrows represent eddy currents which are
the main absorption mechanism of the magnetic component of the microwaves in the metallic powders.
Project Goal and Description Microwave-assisted sintering is a powerful method for the synthesis and processing of ceramic, glassy, polymer and metal powder materials. Compared with conventional heating, microwave heating produces a uniform heating of the entire volume of the sintered material. In case of sintering of dissimilar materials, such as metals, ceramics and/or polymers, the different material properties, for ex. the electrical and thermal conductivity, permittivity, permeability lead to different heating behavior, according to their different absorption of electromagnetic field energy. As the material properties of the end-product strongly depend on the temperature of the sintering process, knowledge of the temperature profiles during the interaction of the material and the microwave field is of high importance. The goal of the present Ph.D. work is the numerical simulation of the interaction of the microwave field with complex materials during the sintering process. Different mesh based methods are available for the numerical simulation of the electromagnetic fields, such as the Finite Integration Technique (FIT). In a first step it is necessary to generate an appropriate model for the complex material, which may be a functional gradient material (FGM) or a bulk composite.
Recently microwave heating emerged as a powerful tool for processing of metallic powders. It was reported in 1999 by R. Roy and coworkers that porous metal powder compacts heat when subjected to microwave irradiation in either electric or magnetic field despite the well known fact that microwaves do not penetrate bulk metals beyond skin depth and thus can not deeply heat metals in a microwave furnace. R. Roy's results show that the porous metal powder compacts are materials with both, effective dielectric and effective magnetic losses, corresponding to effective permittivity and effective permeability of the porous metal compacts. It is essential to study the electric and magnetic properties of metallic powders obtained from FIT simulations. Introducing a computer model of these materials together with an extraction of effective parameters of the mixtures gives us an opportunity to have insight into micrometer scale microwave absorption mechanisms in metallic powders. Computer simulations are performed with the cutting-edge electromagnetic simulation software, CST Microwave Studio® 2008 (CST MWS)
Papers in international peer reviewed conferences,
Talks on Conferences,
Participation in workshops,
summer schools,
study visits and tutorials,
Reports
Oral presentations
 
“Microwave Assisted Sintering”
Advances in Electronic Research KWT 2007 (19-24 August 2007), Riezlern/Kleinwalsertal, Austria
 
“Microwave Assisted Sintering”
12. Symposium Maritime Elektrotechnik, Elektronik und Informationstechnik(8-10 October 2007), Rostock, Germany
 
“Modelling of Magnetic and Dielectric Properties of Metallic and Ceramic Powders in the Microwave Range”
9th International Workshop on Finite Elements for Microwave Engineering (8-9 May 2008), Bonn, Germany
 
“Modelling of Microwave Absorption Mechanisms of Metallic Powders”
20th Workshop on Advances in Electromagnetic Research KWT 2008 (10-15 August 2008), Hardehausen, Germany
 
 
Poster presentations
 
“Full 3D Electromagnetic Simulations of Microwave Heating of Ceramic and Metal Powders”,
Advanced Processing of Novel Functional Materials - APNFM2008 (23-25 January 2008) Dresden, Germany
 
“Extraction of Effective Permittivity and Permeability of Metallic Powders in the Microwave Range”,
Thirteenth Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2008) (11-15 May 2008), Athens, Greece
 
 
Other activities
  • Materials Days 2007(3-4 May 2007), Rostock, Gemany
  • COMSOL Intensive training (19-20 July 2007), Goettingen, Germany
  • CST MCROWAVE STUDIO Training (28-29 August 2007), Darmstadt, Germany
  • CST 3rd European User Group Meeting 2007 (13-14 September), Tegernsee, Germany
  • COMSOL Colloquium zur Elektromagnetik-Simulation (20-21 September 2007), Hannover, Germany
  • Giving lectures on Coupled Simulations (October 2007 - January 2008)
  • CEFC 2008 (11-15 May 2008), Athens, Greece
  • Giving lectures on Coupled Simulations (October 2008 - January 2009)

  •  
     
    Papers:
     
    T. Galek and U. van Rienen, “Microwave Assisted Sintering”
    12. Symposium Maritime Elektrotechnik, Elektronik und Informationstechnik.
    Hrsg.: Nils Damaschke, Universität Rostock, Fakultät für Informatik und lektrotechnik, Rostock 2007
    Publications T. Galek and U. van Rienen, “Microwave Assisted Sintering”
    12. Symposium Maritime Elektrotechnik, Elektronik und Informationstechnik.
    Hrsg.: Nils Damaschke, Universität Rostock, Fakultät für Informatik und Elektrotechnik, Rostock 2007 (Paper)