Mesure de longueur de fissure d'interface en température entre une barrière environnementale et un substrat composite à matrice céramique

The present work concerns the study of a Ceramic Matrix Composite (CMC) intended to be used in hot sections of aircraft engines. As these materials cannot be used alone in engine environments, the presence of a coating acting as an environmental barrier [1] is essential. Coating spallation is critical since the CMC would be exposed to engine environment, which considerably reduces its lifetime. The objective of this work is therefore to increase the understanding of cracking at CMC/EBC interfaces in order to predict the lifetime of the system. Four-point flexural tests with no precrack were conducted. They enable cracks to be initiated through the coating, then delamination and propagation along the interface. These tests were carried out at room temperature and 1 050°C. The instrumentation of the tests with visible light cameras allowed for the analysis of the tests at room temperature thanks to digital image correlation as well as comparisons between experimental and numerical results to locate crack tips and to calculate the interface toughness the loading.