Name: Wojciech K. Gwarek
Affiliation: Warsaw University of Technology, Warsaw, Poland
Presentation Title: Modeling and Measurements of Susceptors for Microwave Heating Applications
email: gwarek@ire.pw.edu.pl
Abstract:
Microwave susceptors are semitransparent metal sheets used to enhance local dissipation of power in a microwave heating process. Accurate electromagnetic characterization of susceptors is therefore essential for the analysis and design of microwave power engineering systems. This work addresses several outstanding issues in this area and presents their new and technologically feasible solutions.
Mores specifically, it is theoretically proved that, from the viewpoint of microwave power reflection, transmission, and dissipation properties, a microwave susceptor is fully characterized by its surface resistivity. Methods of surface resistivity measurements for susceptors are discussed, with focus on a new resonator method. A dedicated split post resonator and single-post resonator are introduced. Further, a surrogate scaled susceptor model is proposed for accurate and effective electromagnetic simulations. Final considerations on an emerging technology of patterned susceptors demonstrate their unexpected and somewhat counterintuitive properties.
Affiliation: Warsaw University of Technology, Warsaw, Poland
Presentation Title: Modeling and Measurements of Susceptors for Microwave Heating Applications
email: gwarek@ire.pw.edu.pl
Abstract:
Microwave susceptors are semitransparent metal sheets used to enhance local dissipation of power in a microwave heating process. Accurate electromagnetic characterization of susceptors is therefore essential for the analysis and design of microwave power engineering systems. This work addresses several outstanding issues in this area and presents their new and technologically feasible solutions.
Mores specifically, it is theoretically proved that, from the viewpoint of microwave power reflection, transmission, and dissipation properties, a microwave susceptor is fully characterized by its surface resistivity. Methods of surface resistivity measurements for susceptors are discussed, with focus on a new resonator method. A dedicated split post resonator and single-post resonator are introduced. Further, a surrogate scaled susceptor model is proposed for accurate and effective electromagnetic simulations. Final considerations on an emerging technology of patterned susceptors demonstrate their unexpected and somewhat counterintuitive properties.
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2009 IEEE MTT-S - Boston, MA
Name: Cristina Leonelli
Affiliation: University of Modena and Reggio Emilia, Modena, Italy
Presentation Title: Control of the Microstructure of Powder Metallurgy Products by Microwave Heating
email: cristina.leonelli@uni-modena.it
Abstract:
Powder metallurgy can benefit from the rapid and selective microwave heating that allows for obtaining materials with unique microstructures and outstanding mechanical properties. In particular, rapid microwave heating was successfully applied to maintain nanostructure in sintered metal parts, thus improving their hardness. The capability of microwaves to convey energy, and not heat, to a reacting system can be used to control the dimensions and microstructure of compounds and coatings prepared by self-propagating high temperature synthesis of metallic powder mixtures.
In this talk, we discuss our recent innovative result of rapid microwave debinding and sintering of stainless steel powder compacts in a single mode applicator. Numerical simulation and experimental results of preparation of intermetallic coatings on titanium surface are presented. We demonstrate the effect of heating selectivity allowing for heating only the reacting components while preserving integrity and microstructure of the substrate. The resulting innovative coatings are characterized by a higher wear resistance as well as an increased toughness. These findings are of practical importance for all mechanical metallurgy sectors and for the energy and transportation sector in particular.
Affiliation: University of Modena and Reggio Emilia, Modena, Italy
Presentation Title: Control of the Microstructure of Powder Metallurgy Products by Microwave Heating
email: cristina.leonelli@uni-modena.it
Abstract:
Powder metallurgy can benefit from the rapid and selective microwave heating that allows for obtaining materials with unique microstructures and outstanding mechanical properties. In particular, rapid microwave heating was successfully applied to maintain nanostructure in sintered metal parts, thus improving their hardness. The capability of microwaves to convey energy, and not heat, to a reacting system can be used to control the dimensions and microstructure of compounds and coatings prepared by self-propagating high temperature synthesis of metallic powder mixtures.
In this talk, we discuss our recent innovative result of rapid microwave debinding and sintering of stainless steel powder compacts in a single mode applicator. Numerical simulation and experimental results of preparation of intermetallic coatings on titanium surface are presented. We demonstrate the effect of heating selectivity allowing for heating only the reacting components while preserving integrity and microstructure of the substrate. The resulting innovative coatings are characterized by a higher wear resistance as well as an increased toughness. These findings are of practical importance for all mechanical metallurgy sectors and for the energy and transportation sector in particular.
Name: Aly E. Fathy
Affiliation: University of Tennessee, Knoxville, TN, USA
Presentation Title: Electromagnetic and Thermal Analysis of High Power Industrial Microwave Ovens for Metal Casting Applications
email: fathy@ece.utk.edu
Abstract:
Using microwave energy in metal casting could cut heating costs by about 30%. However, the design and development of appropriately large microwave furnaces is a challenging multi-physics task that requires addressing concurrently various electromagnetic, thermal, material, and chemical issues. The computational domain of such a problem is exceptionally large, and various materials properties are still unknown at such elevated temperatures. We have developed a multiphysics model using COMSOL that is based on finite elements analysis and includes dynamic modeling of electromagnetics and heat. Both 3D field and temperature distributions are generated using temperature dependent data for various ceramic materials like SiC and alumina. They were carefully measured using a specially designed high temperature dielectrometer probe for the complex permittivity, and a laser heat flash system for the specific heat.
We shall discuss the analysis of two ovens: a modular oven (31cm radius by 62cm height) and a large industrial oven (60 cm radius by 125 cm height). While the results are technically informative, computing such large problems with the present tool requires huge computational resources - for example, many hours per run on a cluster of eight computers. The subject of accelerating modeling and simulation methods for microwave power technologies will be raised for further consideration by the Workshop attendees.
Affiliation: University of Tennessee, Knoxville, TN, USA
Presentation Title: Electromagnetic and Thermal Analysis of High Power Industrial Microwave Ovens for Metal Casting Applications
email: fathy@ece.utk.edu
Abstract:
Using microwave energy in metal casting could cut heating costs by about 30%. However, the design and development of appropriately large microwave furnaces is a challenging multi-physics task that requires addressing concurrently various electromagnetic, thermal, material, and chemical issues. The computational domain of such a problem is exceptionally large, and various materials properties are still unknown at such elevated temperatures. We have developed a multiphysics model using COMSOL that is based on finite elements analysis and includes dynamic modeling of electromagnetics and heat. Both 3D field and temperature distributions are generated using temperature dependent data for various ceramic materials like SiC and alumina. They were carefully measured using a specially designed high temperature dielectrometer probe for the complex permittivity, and a laser heat flash system for the specific heat.
We shall discuss the analysis of two ovens: a modular oven (31cm radius by 62cm height) and a large industrial oven (60 cm radius by 125 cm height). While the results are technically informative, computing such large problems with the present tool requires huge computational resources - for example, many hours per run on a cluster of eight computers. The subject of accelerating modeling and simulation methods for microwave power technologies will be raised for further consideration by the Workshop attendees.
Name: Sebastién Vaucher
Affiliation: Swiss Federal Laboratories for Materials Testing and Research - EMPA, Thun, Switzerland
Presentation Title: Time-Resolved Imaging of Material Changes Under Microwave Irradiation
email: sebastien.vaucher@empa.ch
Abstract:
Although the use of microwave energy in processing and manufacturing of advanced nanomaterials is not new, the present knowledge on the interaction of matter with microwave fields remains essentially limited to observations performed at room temperature, before and after this interaction takes place. In-situ synchrotron radiation diffraction experiments were recently conducted at the Swiss Light Source with the aim to look into the internal mechanisms of high temperature processes.
The present talk shows that the combined use of high brilliance synchrotron radiation sources and fast X-ray detectors enables the real-time observation of the microwave-material interaction and its kinetic features. Information yielded by in-situ time-resolved experiments can greatly enrich fundamental knowledge on the physics of mass transport and structural phase transitions in the presence of electromagnetic fields as well as suggest some means to fine tune microwave processing for a broad variety of nanomaterials. Practical relevance of in-situ synchrotron diffraction method is presented in three examples: phases changes in fast carbothermal reduction of iron ores into steel, nano crystallization of metallic glasses, and the formation and stabilization of aluminium copper iron quasi-crystals. Finally, prospective opportunities of microwave assisted technologies based on our findings are briefly discussed showing potential implications for powder metallurgy, microwave chemistry, catalysis, pharmacy, food processing, biology, or medicine.
Affiliation: Swiss Federal Laboratories for Materials Testing and Research - EMPA, Thun, Switzerland
Presentation Title: Time-Resolved Imaging of Material Changes Under Microwave Irradiation
email: sebastien.vaucher@empa.ch
Abstract:
Although the use of microwave energy in processing and manufacturing of advanced nanomaterials is not new, the present knowledge on the interaction of matter with microwave fields remains essentially limited to observations performed at room temperature, before and after this interaction takes place. In-situ synchrotron radiation diffraction experiments were recently conducted at the Swiss Light Source with the aim to look into the internal mechanisms of high temperature processes.
The present talk shows that the combined use of high brilliance synchrotron radiation sources and fast X-ray detectors enables the real-time observation of the microwave-material interaction and its kinetic features. Information yielded by in-situ time-resolved experiments can greatly enrich fundamental knowledge on the physics of mass transport and structural phase transitions in the presence of electromagnetic fields as well as suggest some means to fine tune microwave processing for a broad variety of nanomaterials. Practical relevance of in-situ synchrotron diffraction method is presented in three examples: phases changes in fast carbothermal reduction of iron ores into steel, nano crystallization of metallic glasses, and the formation and stabilization of aluminium copper iron quasi-crystals. Finally, prospective opportunities of microwave assisted technologies based on our findings are briefly discussed showing potential implications for powder metallurgy, microwave chemistry, catalysis, pharmacy, food processing, biology, or medicine.
Name: José Manuel Catalá-Civera
Affiliation: Technical University of Valencia, Valencia, Spain
Presentation Title: Advanced Microwave Measurements for High-Power Applications
email: jmcatala@dcom.upv.es
Abstract:
Microwave heating processes are in most cases dynamic processes in which the processed workload changes with time. For instance, in drying applications, dielectric properties of the processed material vary dynamically as water is removed, and, as a consequence, some critical parameters of the microwave applicator change dynamically as well. Therefore, data on measurements of such characteristics as impedance, reflections, and dielectric properties varying in the course of microwave heating process may provide unique control capabilities that can be crucial for successful applications.
High-power impedance measurement devices have traditionally been designed as 6-port reflectometers with equispaced receiver diodes in rectangular waveguides. In this talk, we describe new efficient designs and implementations of such devices based on modern Bluetooth integrated circuits. Bluetooth ICs allow effective amplitude and phase measurement in a wide frequency and dynamic range. At the same time, the cost of so constructed devices is very low compared to classical laboratory equipment such as vector network analyzers. This makes them competitive tools in industrial practice.
Affiliation: Technical University of Valencia, Valencia, Spain
Presentation Title: Advanced Microwave Measurements for High-Power Applications
email: jmcatala@dcom.upv.es
Abstract:
Microwave heating processes are in most cases dynamic processes in which the processed workload changes with time. For instance, in drying applications, dielectric properties of the processed material vary dynamically as water is removed, and, as a consequence, some critical parameters of the microwave applicator change dynamically as well. Therefore, data on measurements of such characteristics as impedance, reflections, and dielectric properties varying in the course of microwave heating process may provide unique control capabilities that can be crucial for successful applications.
High-power impedance measurement devices have traditionally been designed as 6-port reflectometers with equispaced receiver diodes in rectangular waveguides. In this talk, we describe new efficient designs and implementations of such devices based on modern Bluetooth integrated circuits. Bluetooth ICs allow effective amplitude and phase measurement in a wide frequency and dynamic range. At the same time, the cost of so constructed devices is very low compared to classical laboratory equipment such as vector network analyzers. This makes them competitive tools in industrial practice.
Name: Monika Willert-Porada
Affiliation: University of Bayreuth, Bayreuth, Germany
Presentation Title: Parameter Analysis of Atmospheric Microwave Plasma Generation in Fluidized Beds
email: monika.willert-porada@uni-bayreuth.de
Abstract:
Fluidised bed technology is widely used in chemical engineering because of its capability of fast, efficient and homogeneous heat transfer in very large volumes of poor heat conducting particulate materials. A significant extension of this processing technology is possible when atmospheric microwave plasma is introduced into fluidised beds containing reactive particulate materials or reactive gases.
This talk describes two examples of new processes which utilise microwave plasma for coating of particulate substrates and for synthesis of a very reactive chemical (TFE). Based on experiments, a model for the mechanism of plasma ignition and sustain is developed. It is experimentally verified, that depending upon the type of particulate solids the emission of thermal electrons or the evaporation of metal from the particulate solids are the ignition controlling steps, whereas the fluidised gas composition in the solid free bubbles governs the sustain of plasma at atmospheric pressure. These results provide important guidelines for further developments in microwave technology with promising applications in the rapidly evolving domain of the powder technology.
Affiliation: University of Bayreuth, Bayreuth, Germany
Presentation Title: Parameter Analysis of Atmospheric Microwave Plasma Generation in Fluidized Beds
email: monika.willert-porada@uni-bayreuth.de
Abstract:
Fluidised bed technology is widely used in chemical engineering because of its capability of fast, efficient and homogeneous heat transfer in very large volumes of poor heat conducting particulate materials. A significant extension of this processing technology is possible when atmospheric microwave plasma is introduced into fluidised beds containing reactive particulate materials or reactive gases.
This talk describes two examples of new processes which utilise microwave plasma for coating of particulate substrates and for synthesis of a very reactive chemical (TFE). Based on experiments, a model for the mechanism of plasma ignition and sustain is developed. It is experimentally verified, that depending upon the type of particulate solids the emission of thermal electrons or the evaporation of metal from the particulate solids are the ignition controlling steps, whereas the fluidised gas composition in the solid free bubbles governs the sustain of plasma at atmospheric pressure. These results provide important guidelines for further developments in microwave technology with promising applications in the rapidly evolving domain of the powder technology.
Name: Matthias Graf
Affiliation: Fraunhofer Institute for Chemical Technology, Pfinztal, Germany
Presentation Title: Simulation of Microwave Plasma Systems
email: christian.hunyar@ict.fraunhofer.de
Abstract:
Microwave generated plasmas excel in low-pressure applications because of high attainable plasma densities and low ion energies. Surface modification is a field in which the good compatibility of microwave plasmas with polymers can be used to develop new lightweight and energy effective mate-rials, e.g., scratch resistant polymer surfaces for automotive applications or coatings for solar cells. For these applications, to process large areas, plasma sources are necessary. The high costs of test-types make further upscaling difficult with current concepts that rely on empirical know-how alone.
To address this problem, we have developed a new simulation model which can be used for flexible design of large-scale plasma devices and processes. It is based on a fluid plasma model. The coupled system of Maxwell's, transport and heat equations for microwave plasma is solved self-consistently and time resolved by a finite element software package for 2D and 3D geometries. In this work we present the simulation results for the Plasmaline(R), a source linearly extended in the 1 m scale. First experimental verification of our model by measurement of plasma parameters (e.g. electron temperature and density) is also shown. Further applications of the model towards the design of new microwave plasma sources for upscaling several industrial processes are finally discussed.
Affiliation: Fraunhofer Institute for Chemical Technology, Pfinztal, Germany
Presentation Title: Simulation of Microwave Plasma Systems
email: christian.hunyar@ict.fraunhofer.de
Abstract:
Microwave generated plasmas excel in low-pressure applications because of high attainable plasma densities and low ion energies. Surface modification is a field in which the good compatibility of microwave plasmas with polymers can be used to develop new lightweight and energy effective mate-rials, e.g., scratch resistant polymer surfaces for automotive applications or coatings for solar cells. For these applications, to process large areas, plasma sources are necessary. The high costs of test-types make further upscaling difficult with current concepts that rely on empirical know-how alone.
To address this problem, we have developed a new simulation model which can be used for flexible design of large-scale plasma devices and processes. It is based on a fluid plasma model. The coupled system of Maxwell's, transport and heat equations for microwave plasma is solved self-consistently and time resolved by a finite element software package for 2D and 3D geometries. In this work we present the simulation results for the Plasmaline(R), a source linearly extended in the 1 m scale. First experimental verification of our model by measurement of plasma parameters (e.g. electron temperature and density) is also shown. Further applications of the model towards the design of new microwave plasma sources for upscaling several industrial processes are finally discussed.
Name: Vadim V. Yakovlev
Affiliation: Worcester Polytechnic Institute, Worcester, MA, USA
Presentation Title: Efficient Techniques of ANN-Based Microwave Imaging in Closed Systems
email: vadim@wpi.edu
Abstract:
Recent demonstration of efficiency of microwave sintering of particulate materials has drawn a strong interest to microwave processing of ceramic, metallic and composite powders as an innovative technique of production of new materials with unique mechanical and physical properties. Since the physics behind microwave sintering is not fully understood yet, there is a significant interest in the computational schemes which would allow for macroscopic modeling of sintering. Applications of the related models are, however, principally held back due to the absence of data on dielectric and thermal properties of the samples under high temperature sintering.
This contribution provides an update on the development of a new technology of microwave imaging for non-destructive evaluation (NDE) of materials in closed cavities. The approach based on artificial neural network (ANN) optimization and backed by 3D FDTD data is shown to be capable of certain types of reconstructing the internal structure of the samples from measured S-parameters. Operational characteristics of two waveguide techniques are considered in detail. First detects a position and size of a spherical or elliptical object in a dielectric body; another reconstructs 2D continuous complex permittivity profiles in the samples. Comparison of actual and reconstructed characteristics shows the accuracy satisfactory for practical needs and suggests that the proposed ANN approach may become an attractive NDE technology applicable to realistic sintering processes.
Affiliation: Worcester Polytechnic Institute, Worcester, MA, USA
Presentation Title: Efficient Techniques of ANN-Based Microwave Imaging in Closed Systems
email: vadim@wpi.edu
Abstract:
Recent demonstration of efficiency of microwave sintering of particulate materials has drawn a strong interest to microwave processing of ceramic, metallic and composite powders as an innovative technique of production of new materials with unique mechanical and physical properties. Since the physics behind microwave sintering is not fully understood yet, there is a significant interest in the computational schemes which would allow for macroscopic modeling of sintering. Applications of the related models are, however, principally held back due to the absence of data on dielectric and thermal properties of the samples under high temperature sintering.
This contribution provides an update on the development of a new technology of microwave imaging for non-destructive evaluation (NDE) of materials in closed cavities. The approach based on artificial neural network (ANN) optimization and backed by 3D FDTD data is shown to be capable of certain types of reconstructing the internal structure of the samples from measured S-parameters. Operational characteristics of two waveguide techniques are considered in detail. First detects a position and size of a spherical or elliptical object in a dielectric body; another reconstructs 2D continuous complex permittivity profiles in the samples. Comparison of actual and reconstructed characteristics shows the accuracy satisfactory for practical needs and suggests that the proposed ANN approach may become an attractive NDE technology applicable to realistic sintering processes.
Name: Yoshio Nikawa
Affiliation: Kokushikan University, Tokyo, Japan
Presentation Title: Microwave Power Applications to Metamaterial and Measurement of Complex Permittivity under NMR Temperature Mapping
email: nikawa@kokushikan.ac.jp
Abstract:
Microwave power is a very efficient source to heat wide-ranging lossy materials. In this talk, two novel methods of obtaining temperature dependent complex permittivity of materials will be presented. For the first method, applicable to low loss materials, cylindrical cavity resonators of TE011 or TM010 mode and heating system in a frequency of 2.45 GHz band have been designed. In the measurement, the output power of vector network analyzer is amplified to heat the material and obtain the complex permittivity by measuring transmission coefficient; temperature of the material is simultaneously measured by an infrared thermometer. The characteristics of composite materials and metamaterials have also been measured and evaluated using this technique.
In the second method, phase shift of T1 signal in nuclear magnetic resonance (NMR) is observed using 0.3T open-type nuclear NMR equipment and used to determine the temperature in the material; measurement of complex permittivity is made using open ended coaxial probe to apply microwave power and obtain reflection coefficient. Using the methods discussed in this talk, complex permittivity of various materials in a wide temperature range can be obtained. The knowledge of material characteristics is crucial for the development of microwave power systems.
Affiliation: Kokushikan University, Tokyo, Japan
Presentation Title: Microwave Power Applications to Metamaterial and Measurement of Complex Permittivity under NMR Temperature Mapping
email: nikawa@kokushikan.ac.jp
Abstract:
Microwave power is a very efficient source to heat wide-ranging lossy materials. In this talk, two novel methods of obtaining temperature dependent complex permittivity of materials will be presented. For the first method, applicable to low loss materials, cylindrical cavity resonators of TE011 or TM010 mode and heating system in a frequency of 2.45 GHz band have been designed. In the measurement, the output power of vector network analyzer is amplified to heat the material and obtain the complex permittivity by measuring transmission coefficient; temperature of the material is simultaneously measured by an infrared thermometer. The characteristics of composite materials and metamaterials have also been measured and evaluated using this technique.
In the second method, phase shift of T1 signal in nuclear magnetic resonance (NMR) is observed using 0.3T open-type nuclear NMR equipment and used to determine the temperature in the material; measurement of complex permittivity is made using open ended coaxial probe to apply microwave power and obtain reflection coefficient. Using the methods discussed in this talk, complex permittivity of various materials in a wide temperature range can be obtained. The knowledge of material characteristics is crucial for the development of microwave power systems.
Name: Lambert Feher
Affiliation: Forschungszentrum, Karlsruhe, Germany
Presentation Title: Microwave Quantum Interactions for Polymer and Composite Curing
email: lambert.feher@ihm.fzk.de
Abstract:
In presence of a microwave field, exposed polymer materials which carry specific molecular rests underlie, in addition to the thermal Brownian motion, a further degree of freedom because of rotational resonances originated uniquely by microwaves.
This talk presents a new quantum representation that explains the origin and behavior of the assigned classical electric conductivity. This representation can be applied for processing ceramics, composites, polymers, nano materials, and many others. It also forms the basis for refined descriptions for energy conversion and absorption mechanisms, leading to new processes and enhanced material properties. The talk will show that microwave coupling can be much more diversified due to correlation effects than the traditional classical approaches are capable to describe. These results give rise to innovative approaches for energy efficient polymer processing for automotive and aerospace applications with microwave technologies. Such technologies are currently investigated in industrial projects at FZK and will be presented at the Workshop.
Affiliation: Forschungszentrum, Karlsruhe, Germany
Presentation Title: Microwave Quantum Interactions for Polymer and Composite Curing
email: lambert.feher@ihm.fzk.de
Abstract:
In presence of a microwave field, exposed polymer materials which carry specific molecular rests underlie, in addition to the thermal Brownian motion, a further degree of freedom because of rotational resonances originated uniquely by microwaves.
This talk presents a new quantum representation that explains the origin and behavior of the assigned classical electric conductivity. This representation can be applied for processing ceramics, composites, polymers, nano materials, and many others. It also forms the basis for refined descriptions for energy conversion and absorption mechanisms, leading to new processes and enhanced material properties. The talk will show that microwave coupling can be much more diversified due to correlation effects than the traditional classical approaches are capable to describe. These results give rise to innovative approaches for energy efficient polymer processing for automotive and aerospace applications with microwave technologies. Such technologies are currently investigated in industrial projects at FZK and will be presented at the Workshop.
discover accurate EM modelling