Materials nondestructive characterization by RF probe in extreme conditions – CANODEMS

The CANODEMS project is focused on the development of a non-destructive radiofrequency (RF) characterization system able to measure electromagnetic properties of materials while being sintered or going through thermal cycling up to very high temperature (1600°C and more). The proposed system is based on a RF near field probe working up to 30 GHz as well as a dedicated calibration kit. Specific properties of numerous materials (hyperfrequency applications, cloaking, shielding) are based on their microstructure (density, grain size, nature). These parameters clearly have a link to their complex permittivity (even surface impedance). It is therefore possible, thanks to a near field probe (dielectric waveguide in our case), to extract the structural properties from the non-destructive measurement of the complex permittivity of a given material. The proposed probes can be used as sensors in an oven in order to measure these properties in real time and to use this sensor as a material properties optimization tool. The proposed system can be used to characterize up to very high temperature the hyper frequencies and mechanical properties of materials being sintered or already fully sintered. The non-destructive probes are capable to bear the high temperatures and are adjustable to different applications:
• real time and in situ monitoring of materials properties during their sintering in a standard oven or specific apparatus (Spark Plasma Sintering, SPS)) • experimental tool for a better understanding of thermal, mechanical or electromagnetic phenomena thanks to the continuous monitoring of the material complex permittivity • measurements of RF properties of sintered materials (dielectrics for microwaves applications, absorbers, …) through thermal cycling
• with the creation of a handheld and compact version of this probe, it can be used to control at ambient temperature different materials after their fabrication (checking of manufactured batches) or upon return from deployment (shielding or cloaking surface of a given platform) at low frequency (2-6 GHz typically).
The designed probes will use high temperature (1600°C) resistant materials based on a dielectric filled (Alumina) or hollow (Graphite) waveguide. The complex permittivity is obtained by measuring the reflected wave coming back from the material placed near the probes. This project is linking competences in terms of hyperfrequency components design and HF materials characterization (Xlim laboratory and CISTEME) and in terms of structural properties of materials (IRCER laboratory) conventionally sintered or through SPS. This work is in direct relation with the Sigma-Lim laboratory of excellence (Labex) associating IRCER and Xlim on a thematic dedicated to materials and manufacturing process for components. CISTEME will support the probes design in the project as well as measurements of complex permittivity. It will use an already existing free space characterization bench to give confirmation with permittivity measurement up to 50 GHz and 800°C. It will also exploit the proposed measurement systems at the end of the project. The targeted materials in the project are linked to numerous applications: - Dielectric materials for HF and microwave applications (Alumina, …) - HF absorbers and cloaking materials - Shielding (Alumina, Silicon Carbide, Boron Nitride) - High temperature materials for space and nuclear applications.