Influence of surface fibre properties and textural organization of a pyrocarbon interphase on the interfacial shear stress of SiC/SiC minicomposites reinforced with Hi-Nicalon S and Tyranno SA3 fibres

SiC/SiC composites reinforced with 3rd generation SiC fibres (Hi-Nicalon S and Tyranno SA3) are attractive for nuclear applications. The mechanical properties of SiC/SiC minicomposites were studied in relation with the nature of fibres and the textural organization of the pyrocarbon interphase. Two different experimental mechanical procedures were used: the push-out test and the tensile mechanical test. The experimental results demonstrate that the interfacial shear stress is higher for a minicomposite reinforced with Tyranno SA3 fibres. It is also shown that the interfacial shear stress depends on the texture of the carbon interphase. Highly anisotropic pyrocarbon interphase increases the interfacial shear stress. To our knowledge it is the first time that the influence of pyrocarbon texture is observed on SiC/SiC composites using Hi-Nicalon S and Tyranno SA3 fibres. It is also demonstrated that push-out tests are more appropriated than tensile tests to highlight differences of interfacial shear stress measurements.