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The microstructure morphologies have been characterized by high resolution laboratory X-ray computed tomography in Carbon Fiber Reinforced Carbon and Silicon Carbide (C/C-SiC) ceramic composites fabricated by Gaseous Silicon Infiltration (GSI) from C/C preforms of three different architectures: 3D stitched cloth fabric; 3D orthogonal woven fabric; and needled shortcut felt. Each composites' microstructure was influenced by the structure of the C/C preform. By incorporating tomography with gravimetric analysis, the 3D distribution of the SiC was visualized, showing a connected SiC network in the needled shortcut felt, and more heterogeneous SiC formation on the surfaces of the fiber bundles in the stitched and woven fabrics. The needled shortcut felt provided the largest contact surface for the GSI reaction and generated~56% volume fraction of SiC, which is almost twice and three times that achieved in the stitched and woven fabrics respectively. Differences in the open and closed pore distributions were also measured by mercury intrusion porosimetry and tomography.

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