Development, characterization and resistance to ablation of ultra-refractory complex composition ceramic materials (M/F)

Job Description

Thesis Subject

Context

During atmospheric re-entry, the leading edges of spacecraft are subjected to extreme environments that require advanced materials. Currently, C/C or C/Resin composites fulfill these functions; however, their sensitivity to oxidation leads to material consumption, which alters the geometry of the components. Due to their melting points exceeding 2500°C, Ultra-High Temperature Ceramics (UHTCs) are potential candidate materials, whether in the form of coatings, bulk parts, or as a matrix for carbon-fiber-reinforced composites.
Nevertheless, these materials must perform under diverse conditions, and conventional compositions may reach their limits. In the field of metallurgy, the emergence of High-Entropy Alloys (HEAs)—alloys composed of at least four elements in near-equimolar proportions—has opened new research horizons due to properties that surpass those of conventional alloys. Consequently, High-Entropy Ceramics (HECs) have garnered significant interest among researchers in recent years, as they offer the potential to achieve unprecedented levels of performance.

Objectives and Methods

The aim of this PhD research is to synthesize ultra-refractory high-entropy ceramics, or more broadly, ceramics with complex compositions. Initially, thermodynamic calculations will be conducted to determine the expected phases and their compositions based on the overall chemical makeup. The synthesized materials will then be characterized and densified into pellets or integrated into composites. Their oxidation resistance will be evaluated using various techniques (laser, plasma torch, or oxy-acetylene torch, etc.). By understanding the oxidation mechanisms, compositional modifications will be made to optimize the materials' ablation resistance.
Once high-interest compositions have been identified, the second challenge of this doctorate will be to incorporate them into carbon-fiber-reinforced composites or to directly develop C/UHTC high-entropy composites.

Your Work Environment

The LCTS is a laboratory located on the Bordeaux campus; it is a joint research unit under the joint supervision of four institutions – the CNRS, the University of Bordeaux, the Safran Group, and the CEA. It has already conducted 36 years of upstream research on refractory composites, ultra-high-performance materials used in the aerospace, space, and energy sectors. It is a unique team working in project mode in close partnership with its non-academic co-supervisors. There are currently 34 permanent staff members, around fifteen doctoral students, and four postdoctoral researchers.

Constraints and risks

None

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions