Generating 3-dimensional microstructure models of porous ceramic matrix composites by means of X-ray tomography and FIB-slicing

Ceramic matrix composites (CMC) are developed for providing a high damage tolerance compared to monolithic ceramics. The mechanical behaviour of CMCs is defined by the properties of the constituents and the complex microstructure, which is controlled by the processing parameters. In this study the 3-dimensional microstructure of an all oxide porous CMC has been characterized on different length scales, utilizing non-destructive X-ray tomography in the range from mm to μm and combined sequential focused ion beam (FIB) ablation and scanning electron microscopy in the submicron range. The derived virtual microstructures were analysed, and data were used for generating numerical models for further mechanical or thermal analyses by finite element method. The CMC material was processed at DLR by winding a continuous alumina fibre bundle, which is infiltrated by aqueous alumina slurry, onto a mandrel and further sintering of the generated ceramic ‘green body’. The result is a CMC with complex hierarchical microstructure. Fibre arrangement, fibre volume fraction, and matrix porosity can be varied in a wide range.