Abstract: Monotonic tensile experiments at room temperature and 1200℃ were performed to investigate the mechanical behaviour of 2D-SiC/SiC composites. The microstructures of specimens were observed by using scanning electron microscope to analyse the damage modes and failure mechanisms. The results indicate that the stress-strain responses of 2D-SiC/SiC composites under tensile loading at both room temperature and 1200℃ are bi-linear and damage appears at the high stress level. Their tensile strengths are fairly close, but the fracture strain at 1200℃ is higher than that at room temperature. Specimens at both room and high temperature demonstrate ductile behaviour, but their pullout length of fibre and smoothness of fracture surfaces are different. Transverse matrix cracking, longitudinal tensile fractures of warp tows with serious interface debonding, and axial splitting failure of weft tows with intact fibres are the main damage mechanisms. The high temperature oxidation was found to have an influence on the properties of fibre-matrix interface of 2D-SiC/SiC composites. The weak interface and decrease of interfacial sliding stress result in the longer pullout length of fibre at 1200℃ in the oxidation environment, and therefore, 2D-SiC/SiC composites has high fracture toughness at 1200℃.

Key words: composites, ceramic matrix, mechanical behaviour, damage, high temperature, failure mechanism