Aurélie JULIAN-JANKOWIAK, Jean-François JUSTIN, Antoine DÉBARRE, Damien BAUTISTA

DOI Number; N/A

Conference number: HiSST-2025-281

Ultra-High Temperature Ceramics (UHTC) are good candidates to fulfil the harsh requirements of hypersonic applications such as very high temperatures (>2000°C) and oxidizing atmospheres. In this context, Onera is working on the development of new UHTC compositions and UHTC matrix composites (UHTCMC) but also on the development of home-made laser test benches (3 kW CO2) allowing the coupling or decoupling of thermal, mechanical et chemical stresses. Thus, the influence of the composition on the oxidation mechanisms of UHTC were studied in several oxidizing conditions through post-mortem scanning electron microscope examinations or using real-time monitoring of thermal
oxidation. This work is focused on monolithic materials with optimised composition based on diborides compounds and composites with different ultrarefractory matrices. After manufacturing and microstructural characterizations (particle size, porosity and composition, UHTC and UHTCMC samples were submitted to high thermal flux under air or water vapour. Then, ultra-high temperature laser thermogravimetric analysis is used to track the sample weight during oxidation in air. The main interest is to study the mass variation above 1600°C in air and with very high heating rate. These characterizations allow us to propose more precise oxidation mechanisms with temperature. Afterwards, samples are characterized with SEM/EDS to confirm the oxidation mechanisms. For example, at 2000°C, weight gain is lower for ZrB2-based materials than for HfB2-based ones. However,
final microstructures are strongly different and the SiC-depleted layer is 7-times larger for HfB2-based materials.

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In Categories: 1.Events, 1.HiSST 2025, Materials and Structures for vehicle and all subsystems
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