Overview On The Self-Sealing Process In The Sicf/[Si,C,B](M) Composites Under Wet Atmosphere At High Temperature

Ceramic Matrix Composites such as SiC/SiC are proposed for applications in the aeronautical and space domains because of their thermomechanical properties and their resistance to corrosive atmosphere. The matrix cracks represent pathway for oxygen diffusion up to fibers. The incorporation of boron bearing species such as B4C in the matrix allows a self-healing process of these cracks from temperatures around 500 degrees C by formation of B2O3, a liquid oxide. However, in presence of water vapour, boron oxide forms gaseous hydroxide species leading to a reduction of the self-healing capability.Our objective was to understand the role of the borosilicate glassy phase, formed by simultaneous oxidation of the different matrix constituents, in the self-healing process of cracks across this multilayered matrix. Finally, under moist air, the sealing appears as a compromise between a quick poorly stable boron-enriched oxide formation and a slower generation rate of a much more chemically stable boria-containing phase.