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Sujet de stage / Master 2 Internship

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ToughGlasses: Researching tomorrow’s glasses today

Contact: ROUNTREE Cindy, , cindy.rountree@cea.fr, +33 1 69 08 26 55
Summary:
This project is a fundamental CNRS-joint research project (PRC) motivated by the need to improve and assess the glasses’ mechanical durability over the long term. Glasses are integral parts of heat resistant technologies, protection panels, low-carbon energies, satellites…. These systems and others undergo a variety of damage (stress corrosion cracking, sand storms, external irradiations, high temperatures…) which can lead to premature failure and alterations of the physical and mechanical properties. Glasses that undergo amorphous phase separation are known to be crush resistant. However, their Stress Corrosion Cracking (SCC) properties are outside the current knowledge available in literature. Hence, the question here how does the SCC behavior change in an amorphous phase separated glass versus is pristine counterpart.
Possibility of continuation in PhD: Oui
Deadline for application:30/03/2018

Full description:
"ToughGlasses" is a fundamental research project motivated by the need to improve and assess glasses mechanical durability over the long term. Glasses are integral parts our daily lives (buildings, cars, dishes…) along with being integral parts of heat resistant technologies, protection panels (smart phones, plasma screens…), low-carbon energies (protection for solar panels) and satellites in outer space to name a few. These systems and others undergo a variety of damage (consumer use, sand storms, external irradiations, high temperatures…) which can lead to premature failure and/or alterations of the physical and mechanical properties. Frequently, post-mortem failure studies reveal material flaws which were propagating via Stress Corrosion Cracking (SCC). A recent question arriving in the field has been: Can the Amorphous Phase Separation (APS) of SiO2-B2O3-Na2O (SBN) glasses provide the necessary structure to enhanced SCC behavior? ToughGlasses aim is to fill this gap and to unravel the secret behind enhanced SCC behavior.

The Ph.D. candidate will have the opportunity to study the physical, mechanical and stress-corrosion cracking properties of APS glasses. The primary objective of this study will be to observe stress corrosion crack propagation in situ and the analysis of fracture surfaces in several pristine and APS glasses. Hence, providing information on environmental limit of stress corrosion cracking and understanding of how the crack growth occurs in APS glasses. This method was previously used in our group to study the process zone size versus the crack front velocity in pure silica (SiO2) and several SBN samples. Repeating this study for SBN APS glasses compositions will aid in the understanding of how the physical structure of glasses alters the mechanical properties. In conjunction with the primary objective, the candidate will have the occasion to characterize the elastic properties of the samples and their structures (Raman, NMR spectroscopy, X-ray absorption …) with various collaborators including collaborators in CEA, DEN and University of Rennes. This will allow for a comparison of the fracture behavior of glasses with other macroscopic and microscopic properties.

Logistically, the PhD candidate will be co-advised by C. L. Rountree at CEA and F. Célarié at Université de Rennes 1. Glass formation and preliminary tests will occur at Université de Rennes 1 and stress corrosion cracking tests along with other tests will be carried out at CEA. In conclusion, the theme of this project is the comprehension of the source of the changes in the macroscopic property, and in particular how to control the stress corrosion cracking properties by varying the structure of glasses through Amorphous Phase Separation.
Technics/methods used during the internship:
AFM, NMR, RAMAN

Laboratory
Tutor of the internship

 

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