Description du sujet de thèse

The doctoral work will evaluate the oxidation behavior at high temperature in the presence of water vapor of chromino and aluminoformers alloys according to the hydrodynamic conditions prevailing around the parts.

For this, the study will be divided in three main parts:

1- The development of the instrumented test rig will be completed during this work; it requires several technical adaptations for the automated handling of samples on the one hand, and the realization of gas mixtures upstream of the device. The assembly will be calibrated to control the test conditions.

2- IN625 alloy samples will be oxidized in the presence of different water vapour contents and with different flow rates. These tests involve monitoring the masses of the samples as a function of time and then characterizing them post-mortem. These characterizations will be conducted using X-ray diffraction, electron microscopy and X-ray photon spectrometry to assess the area affected by oxidation. The comparison of these different results should make it possible to identify the main parameters and to evaluate the influence of the water vapour content of the environment and the hydrodynamic conditions on the velocity laws usually used. Protective oxide layers will also be characterized using transmission microscopy tools to understand the role of water vapour in the growth process of these oxides.

3- The understanding of these effects requires the modeling of hydrodynamic conditions using numerical tools. The composition of the gas phase and the surface flow velocities of the samples will be evaluated and the results compared with the structural changes observed. Microstructural modifications in the alloy will be evaluated and confronted with numerical simulations.

Contexte de travail

The work will take place within the framework of the ANR DYNAMIC consortium made up of the academic laboratories IJL, CIRIMAT, LGC, Air Liquide and Safran. The PhD student will be mainly based at the Jean Lamour Institute but will have to move to the LGC of Toulouse for the part dedicated to modeling. He/she will be assisted in his work by an engineer with whom he/she will continue the development of the test rig.
The Institute Jean Lamour (IJL) is a joint research unit of CNRS and Université de Lorraine.
Focused on materials and processes science and engineering, it covers: materials, metallurgy, plasmas, surfaces, nanomaterials and electronics.
The IJL has 263 permanent staff (30 researchers, 134 teacher-researchers, 99 IT-BIATSS) and 394 non-permanent staff (182 doctoral students, 62 post-doctoral students / contractual researchers and more than 150 trainees), of 45 different nationalities.
Partnerships exist with 150 companies and our research groups collaborate with more than 30 countries throughout the world.
Its exceptional instrumental platforms are spread over 4 sites; the main one is located on Artem campus in Nancy.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

This project will require some travel to Toulouse as part of the partnership. The risks associated with this study are mainly related to the use of equipment at high temperature (1100 > T > 700°C) and to water vapour at very high temperatures.

Informations complémentaires

The candidate will have a Master Degree in Chemistry, Chemical Engineering or Physical Chemistry and the following skills in order to be able to carry out the different tasks of the work:
- practice on the development of experimental reactors (some notions of vacuum, electronics, fluid flow, etc. would be appreciated),
- experimental practice of chemical reactivity of materials (high temperature if possible),
- use of thermodynamics and numerical tools for predicting chemical balances,
- practice of common methods (XRD, SEM) for physical characterization of materials,
- good oral and written English language practice,
- good written and oral communication skills,
- good willingness to work as a team.