DINAWAVE: A Project for High Performance Microwave Sintering and Dynamic Dielectroscopy

DIMAS Research Group is working in a R+D Project entitled High Power Microwave Devices for Dynamic Dielectrometry and High Performance Masterials Sintering (Dispositivos De Dielectrometría Dinámica De Microondas De Potencia Para Sinterizado De Materiales De Alto Rendimiento)

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The Project has the reference number TEC2012-37532-C02-01, has received funding from Ministerio de Economía y Competitividad (MINECO) and is co-funded by ERDF (European Regional Development Funds).

It is led by Dr. Felipe L. Peñaranda Foix (from DIMAS Research Group at ITACA Research Institute at Universidad Politécnica de Valencia) and it funded for a 3-years period (from 01/01/2013 to 31/12/2015) with a total amount of 160290.00€.

A brief summary of it is:

In order to optimice the energetic sources in industrial processes, new heating techonologies are arising. Microwaves are an electromagnetic energy in such a way that during the heating process the materials absorb the eletromagnetic energy and convert it into heat. This process is quite different from the conventional ones where the heat is transferred by conduction, radiation and convection mechanisms.

The main advantages of this technique can be summarized in 3 points: time processing reduction, production cost reductions and environmental benefits. The, microwaves are clear alternative to conventional methods, saving up to 70% of energy in the whole sintering process. This technique is starting being part of the really new and innovative eco-green technologies.

The difficulties inherent to microwave with the unknowledge of the heating process with the electromagnetic fields make people to be away from these techniques, but they are a very powerful technique for the sintering of new materials and to control their phases and nanostructures. Then this technique opens the possibility to get ceramic materials with a combination of exceptional functional and structural properties.

In this context, this coordinate Project has as a global objective to sinter, using microwaves, advanced nanostructured ceramic materials with singular properties and dimensions near net shape, taking into account quality, cost, sustainability, etc, looking always for eco-efficient processes and products

The final objective of this project will be achieved through the following partial objectives:

1) Ceramic nanopowder selection.

2) Moulds and/or susceptors design and optimization to sinter the selected ceramic materials.

3) To define the cell design strategies for the materials’ sintering for its optimization in terms of heating and performance, as well as the measurements.

4) To create electromagnetic characterization tools appropriated for the designed cells in the previous objective.

5) To design dynamic resizing systems for the sintering cells, to follow an optimal and continuous heating profile.

6) To study the parameters of the sintering, giving a feedback to the microwave applicator design.

7) To study and to characterize the materials properties: mechanic, thermal, optic, magnetic and microstructutal.

Finally, it is worth mentioning that during the 1st year the following research publications has been obtained:

[1] R. Benavente, A. Borrell, M. D. Salvador, O. García-Moreno, F. L. Peñaranda-Foix and J. M. Catalá-Civera, “Microwave Sintering of Fully Dense b-Eucryptite Ceramics with Very Low Thermal Expansion”. EUROMAT 2013, Seville, 8-13 September (poster)

[2] A. Borrell, M. D. Salvador, G. Iranzo, M. Miranda, F. L. Peñaranda-Foix and J. M. Catalá-Civera, “Microwave Sintering of Fully Dense HAP nanostructured and HAP/TCP Composites: Enhancement of Mechanical and Microstructural Properties”. EUROMAT 2013, Seville, 8-13 September (poster).

[3] Felipe L. Penaranda-Foix, Jose M. Catala-Civera, Pedro J. Plaza- Gonzalez and Antoni J. Canos-Marin, “Temperature Dependence of Material Permittivity Using Cylindrical Cavities with Insertion Hole”. 14th International Conference on Microwave and High Frequency Heating (AMPERE 2013), Nottingham, UK, September 2013 (oral session).

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Thesis on microwave internal gelation

Last July 19th, 2013, the student María Cabanes Sempere defended her Thesis at Universidad Politécnica de Valencia (UPV). The PhD is entitled “Innovative production of nuclear fuel by microwave internal gelation” and is the result of a close collaboration between PSI (Paul Scherrer Institute) in Villigen (Switzerland) and research group DIMAS at ITACA Research Institute at UPV.

The work was awarded with the Cum Laude mark and can be found in http://riunet.upv.es/handle/10251/31641.

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The Thesis includes a first part with a finite difference time domain (FDTD) thermal model capable to determine the thermal behaviour of a definite point inside a material during heat processing.
Secondly, possible microwave cavity designs for Microwave Internal Gelation (MIG) are researched. The cavities (selection of modes, resonant frequency, Q-factor, etc.) and its subsequent characterization for the coupling of energy are explained. Furthermore, the power transfer mechanisms of the cavities are explained using the perturbation method to analyse the losses when a dielectric sample is placed inside a cavity.
Next, the main parameters dealing with the heating of a material by microwaves are introduced. At this point, a new procedure that enables the measurement of dielectric properties of aqueous droplets freely falling through a microwave cavity is developed.
Finally, the MIG system for the laboratory practice of the high frequency heating is implemented and successful production of gelated spheres shows the favourable usage of microwave for the production of SP-fuel by internal gelation.

In the frame of this Thesis, several publications were made in journals and international conferences. The two results published in ISI journals are:
[1] M. Cabanes-Sempere, J.M. Catala-Civera, C. Cozzo, S. Vaucher, M.A. Pouchon, “Innovative production of nuclear fuel by Microwave Internal Gelation: Heat transfer model of falling droplets”, Prog. Nuclear Energy, vol. 57, pp.111-116, May 2012. doi: 10.1016/j.pnucene.2011.12.011

[2] M Cabanes-Sempere, J. M. Catalá-Civera, Felipe L. Penaranda-Foix, C. Cozzo, S. Vaucher and M. A. Pouchon, “Characterization method of dielectric properties of free falling drops in a microwave processing cavity and its application in microwave internal gelation”. Measurement Science and Technology Volume 24 Number 9, 2013. doi: 10.1088/0957-0233/24/9/095009 (http://iopscience.iop.org/0957-0233/24/9/095009/)