Most of materials produced and utilized in industry are heterogeneous. Typical examples include porous media, polycrystalline materials and composites. The different phases present in such materials constitute a material microstructure. The size, shape and spatial distribution of the microstructural constituent and their chemical composition largely determine the macroscopic overall behaviour of these multi-phase materials. The main properties of interest for industrial applications (such as thermal transport, strength …) have a direct relation with the morphology and the chemical composition of these materials. Thus the amount of each phase/porosity, the connectivity of phase/porous network, the size of the grains/pores, phases change… are all key parameters for the optimisation of the heterogeneous materials to be employed for specific applications.
In this study we propose to characterize some porous ceramic materials during thermal loading, in particular to investigate their microstructural and chemical composition changes occurring during a controlled heating rate. A direct characterization of the dynamical phenomena during loading would greatly improve our knowledge of the final properties of such materials in service (estimation of effective properties).
For that, several techniques will be investigated to collect morphological, crystallographic and chemical information, such as:
- In-situ 3D observations by X-Ray tomography experiments carried out with a standard laboratory tomography for micron resolution, and a fast X-Ray Tomograph located at the ESRF for sub-micron resolution (dependence on the observation scale).
- Environmental Scanning Electron Microscope (ESEM) which permits variation of the sample environment through a range of pressures (up to 50 torr), temperatures (up to 1500 °C with a hot-stage equipment), and gas compositions.
- X-Ray diffraction characterization of crystallinity and phase composition
all of them under a controlled heating rate.
We will also evaluate the methodology approach. The classical one where sample is quenched before analysis will be studied (cooling rate effects – absence or not detailed information regarding the intermediate steps in the process because of large gaps in the temperatures…).
Finally, we will establish some relationships between these morphological and chemical dynamic changes obtained under controlled temperature conditions and final properties of these materials in service.
This study is made in collaboration between Saint Gobain CREE and MATEIS laboratory, INSA Lyon.
Study duration and location: one year, Lyon, France.
Approx. net salary: 2000 €/month
Please send an intention letter + your resume to: sylvain.meille[ at ]insa-lyon.fr
Link: not found
Country: France
