Microstructural analysis of SiC/SiC composites by X-ray tomography scans of progressive CVI matrix deposition

SiC/SiC composites are a candidate material for fuel cladding tubes in fission nuclear power plants.Under external mechanical loading, this material exhibits a pseudo-ductile behaviour as the macroscopicconsequence of internal matrix micro-cracking. The evolution of the micro-cracks, which influence the elastic,thermal and environmental barrier properties, is strongly dependent on the composite microstructure. Imagebased numerical simulations of damage evolution therefore require accurate representation of themicrostructure, and can be guided by techniques such as X-ray computed tomography (XCT). To address theproblem of low contrast between SiC fibres and SiC matrix, we have applied successive XCT scans toincremental matrix depositions by chemical vapour infiltration to examine the development of the SiC matrixand porosity.