Microstructure Characterization by X-Ray Computed Tomography of C/C-SiC Ceramic Composites Fabricated with Different Carbon Fiber Architectures

Abstract

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.

Characterization of the oxidation of C/C/SiC composites by Xray micro-tomography

“…Also, while there are four phases in the 2D-RMI composite (porosity, carbon, SiC and free Si), only three phases are discernible on the grey scale histogram, the dissociation between SiC and free Si being not possible. A dissolution of the Si phase as proposed by Wan et al could be performed to distinguish the Si and SiC phases [30].…”

“…However, in recent years, the practices to observe microstructure have gradually changed with the development of non-destructive techniques such as tomography. This technique has already been used by few authors to characterize the microstructure of C/C/SiC composites during mechanical tests [27], [28], between different stages of the manufacturing process [29], [30] or after oxidation of the material [31]. For the time being, the authors have been satisfied with qualitative characterizations, but this characterization technique allows to evaluate in a more quantitative way the quantity of consumed carbon during different heat treatments.…”

XCT damage evaluation and analysis of SiC/SiC turbine guide vanes after thermal shocks

“…The shape and position of the fiber tows in 3D woven architecture was analyzed and characterized by the area, aspect ratio, and orientation of the cross‐section. Wan et al 17 . characterized three different architectures, that is, 3D stitched cloth fabric, 3D orthogonal woven fabric, and needled short cut felt, in C/C–SiC composites using the XCT, and analyzed the relationship between the microstructure and mechanical and oxidation properties of the composites.…”

Pore structure characterization of oak via X-ray computed tomography

“…This technique can characterize samples with 3D structures at different scales. It has been successfully applied to investigate a variety of porous materials (Corigliano et al 2017;Borges et al 2019;Wan et al 2019;Zhu et al 2019). In the wood science field, researchers have used XCT to successfully observe the shrinkage behavior of wood (Taylor et al 2013).…”