The Interaction of Surface Engineering and High Temperature Corrosion Protection

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Fibre strength selection and the mechanical resistance of fibre-reinforced metal matrix composites

For predicting the strength of fibre-reinforced metal matrix composites, the in situ fibre strength value has to be introduced in the calculations. Tension tests series have been conducted on SiC fibres (SCSO and SCS2 TEXTRON) before and after chemical interaction with a pure liquid aluminium bath and the reacted fibres have been tested before and after dissolution of the aluminium coating simulating the metallic matrix around the fibres. The results obtained for the different fibre batches show that the in situ fibre resistance may differ significantly from the strength of as-received or extracted fibres that is usually adopted in the models

Evolution microstructurale à haute température de barrières thermiques déposées par évaporation (influence sur la conductivité thermique et le module d'élasticité)

LIMOGES-ENSCI (870852305) / SudocPARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

ANALYSE D' INCLUSIONS D'OXYDES RESPONSABLES DE DÉFAUTS DE SURFACE INTERNE APPARAISSANT AU COURS DE LA FABRICATION DE TUBES SANS SOUDURE

Des analyses à la microsonde électronique et des observations au microscope électronique à balayage ont permis d'identifier les inclusions d'oxydes responsables de défauts de surface interne dans la fabrication de tubes sans soudure, et de proposer un mécanisme de formation de ces défauts.Based on EPMA analysis and S.E.M. observations of oxide inclusions, a mechanism is proposed for the formation of interna1 defects in seamless tube

Video Transect-Based Coral Demographic Investigation

Demographic studies that quantify species’ performances for survival, growth, and reproduction are powerful means to characterize sources of demographic bottlenecks and predict community dynamics. However, they require fine-scale surveys of populations in the field, and are often too effort-intensive to be replicable at a large scale and in the long term. We developed a standardized digital approach for extracting demographic data on species’ abundances, sizes, and positions within video transects, enabling back-from-the-field data acquisition and therefore optimizing time spent in the field. The approach is based on manual species identification, size measurements, and mapping in video transects, mimicking what is traditionally performed in the field, though it can be automated in the future with the deployment of artificial intelligence. We illustrate our approach using video surveys of a reef-building coral community in New Caledonia. The results characterize the composition of the coral community and demographic performances as key ecological indicators of coral reef health, shed light on species’ life strategies and constraints to their demographics, and open paths for further quantitative investigations. Key findings include the diversity of life strategies with contrasting levels of investment in survival, growth, and reproduction found among the six taxa dominating the coral community (Acropora, Montipora, Porites, Galaxea, Favia, Millepora), indicating the diversity of demographic paths to ecological success. Our results also indicate that several species have adapted mechanisms to prevail under limiting hydrodynamic environments through the propagation of coral fragments. Our approach facilitates image-based demographic investigations, supporting endeavors in ecology and ecosystem management

Influence de la pression sur la conductivité thermique de barrières thermiques

Les revêtements de zircone yttriée déposés par projection plasma sont utilisés comme barrières thermiques pour protéger des pièces des moteurs aéronautiques, en particulier les parois de chambres de combustion. La diffusivité thermique d'un tel matériau a été déterminée, à température ambiante et pour des pressions allant de 10 à 105 Pa, par la méthode laser-flash (laser CO2, λ = 10,6 µm). Les variations en fonction de la pression de la conductivité thermique peuvent être décrites par un modèle simple tenant compte du fait que la conductivité thermique du gaz contenu dans les microfissures est une fonction de la pression et de leurs dimensions. Ces résultats permettent de décrire l'influence d'un traitement thermique et montrent que la valeur de la conductivité thermique dans les conditions d'utilisation peut être significativement plus élevée que celle déterminée à basse pression ou même à pression ambiante