Microstructural and interfacial characterization for protective thin films in extreme environments

The development and optimization of coatings towards their application are of major importance especially when the components they protect are exposed to aggressive media. Extreme environments impose strong constraints on the design of the film and its interface with the substrate. Moreover, various degradation mechanisms such as the ones we study (corrosion, high-temperature oxidation, abrasive wear and irradiation mainly) can have very different and local effects. As a result, refined coating solutions are under development and need to be characterized. Indeed, fine, accurate and multi-scale characterizations prior to and after ageing tests constitute the major comprehension and analysis tool. The coatings concerned are nanostructured films, high-entropy alloys, MAX-phase, metallic oxides and nanometric multilayers. Because they all include nanometer-scale characteristics (particles, layers or simply interface), they require high-resolution analyzes which is possible with Transmission Electron Microscopy (TEM). This internship will be dedicated to the TEM analysis of coated samples before and after their degradation in extreme environments.

LOCATION

NTU Singapore
School of Materials Science & Engineering
50 Nanyang Avenue, Singapore 639798

CONTACT

NTU: Dong ZHILI, ZLDong@ntu.edu.sg

 

6-months internship on the monitoring of reactive magnetron sputtering of complex concentrated alloys

Complex concentrated alloys (or CCA) and their compounds (oxides, nitrides, carbides…) have been gaining interest for a decade and infuse innovation in the metallurgy field. Academic players use two main synthesis routes, arc melting for bulk materials and physical vapor deposition (PVD) for thin films along with numerical predictive tools, thanks to their high-throughput capabilities that are required to explore the potential composition space of such materials. If many studies focus on the elaboration of thin films of CCA and their compounds deposited by PVD, and more specifically magnetron sputtering, there is still not a lot done on the understanding of fundamental phenomena during the deposition process and their influence on the characteristics and the performances of the coatings. This project proposes to investigate and evaluate several characterization techniques for the monitoring of the reactive deposition of CCA from an alloyed target that has already been studied for non-reactive deposition in CEA: (i) LIBS (Laser Induced Breakdown Spectroscopy) analysis to relatively trace elements in the coating and in the target, (ii) optical emission spectroscopy coupled with (iii) an ultra-high-speed camera to study the species in the plasma along with their dispersal between pulses, (iv) the measurement of the energy distribution of ionized species from the plasma and finally (v) the quantification of coating thicknesses and growth rates by PTR (PhotoThermal Radiometry).

This project is fully integrated into the industrial IMPACT Chair (Innovative Materials and Processes Accelerated through Computing Technologies) from INSTN (French National Institute for Nuclear science and Technology).

It is expected to be extended into a PhD project by September 2020.

Profile

Master degree in Material Science and Engineering. An experience in thin film deposition would be appreciated, along with a recommendation from the head of studies and the last internship supervisor.

Localization

Physico-Chemistry Department of CEA Saclay
91191 Gif-sur-Yvette

Contact

Alexandre MICHAU : alexandre.michau@cea.fr