Missions

Context
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To address the current and future energy, environmental, and economic challenges of air transport, significant efforts are being directed to making next-generation aircraft turbofan engines more environmentally friendly and economical. Consideration is being given to replacing key materials—generally nickel-based superalloys—that make up turbine blades with ceramic matrix composites (CMCs). These composites combine lightness, thermomechanical strength and damage tolerance, operate at higher temperatures (1450°C ≈ 2700°F), and have longer lifespans. The study presented here focuses on the development of CMCs based on the silicon-carbon-nitrogen (Si-C-N) ternary system, manufactured using a hybrid PIP (Polymer Impregnation & Pyrolysis) - CVI (Chemical Vapor Deposition) process from a ceramic fiber preform. This process requires optimization, whereby the structure of the porous matrix prepared by PIP must allow for optimal gas permeability.
Objectives and Methods
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This study aims to investigate the infiltration of porous matrices obtained by PIP using an approach based on 3D imaging and numerical simulation. The objective is to support the development of the most "infiltrable" ex-PIP matrices by characterizing the spatial organization of these porous media and numerically predicting the infiltration of the final matrix by CVI. To this end, X-ray tomography acquisitions will be performed; the images will then be analyzed and processed to produce (i) information on pore distribution and (ii) computational domains to simulate CVI cycles.

Activités

• Materials studied: Simple and pre-infiltrated fibrous textures using PIP, provided by project partners.

• Acquisitions: X-ray tomographs will be taken using a laboratory instrument (Placamat) and at the synchrotron. Micrographs (LM, SEM) will also be provided.
• Data processing: The tomographic data will be processed using image analysis software already available at the LCTS. This will generate two types of computational domains:
(i) porosity-calibrated images (i.e., images whose gray levels correspond to the local porosity value), with identification of the local fiber orientation;
(ii) higher-resolution binarized (segmented) images.

• Analyses: Quantification of porosity, pore size distribution, and calculation of effective transport properties using in-house developed software.
• Simulations: Performing multi-scale infiltration simulations, based on previous images, using internal tools/software.

Compétences

PhD in Process Engineering/Chemical Engineering
Skills in multiphysics numerical simulation and related domains
English language : B1 level
Basic knowledge of programming languages (C,Fortran, Python, ...)
Personal skills: Rigor, autonomy, analysis capabilities, teamworking and communicational skills.
A marked interest for research and innovation are highly desirable.

Contexte de travail

LCTS is a joint lab of CNRS, Bordeaux University, CEA and Safran, located on the Bordeaux Campus. It has 37 years of experience in basic science research on refractory composites. These high-performance materials are used in aviation, space, energy & industrial applications. LCTS is single research team working in project-oriented mode, in strong relation with its non-academic stakeholders. Currently it includes 34 permanent staff members, plus some 15 PhD candidates and 4 post-doc researchers.

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

Work in a restricted area. Admission subject to the decision of the Defense and Security Officer of CNRS .
Partnership with IrCer Limoges and Safran Ceramics