Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

Abstract

The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a "node-bond" geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9 % for the composite, amid which there is about 7.1~9.3 % closed micropores.

Three‐dimensional measurement and cohesive element modelling of deformation and damage in a 2.5‐dimensional woven ceramic matrix composite

“…The SiNO f /BN ceramic matrix composite: (a) 2.5‐dimensional fabric architecture and the coordinate system used in the present study, (b) synchrotron X‐ray tomography image of the microstructure (porosity is dark), (c) laboratory X‐ray tomography of the central region of the sample and (d) the macroscopic porosity of the sample, extracted from (c). [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…The fibre content of the composite was ~40% by volume. The matrix material is distributed mainly between the fibres of the warp tows in regions where they do not cross the weft tow fibres; here, the material was less compressed during the manufacturing process . The mechanical properties of the fibres, matrix and bulk composite (tested in flexure with the tensile stress parallel to the weft fibres) are summarized in Table .…”

“…Image‐based models of composites have been developed that use segmentation of X‐ray tomographs to define the positions and shapes of fibres, pores and matrix . Because of the scale of the model required here to simulate the full specimen without using homogenization, a mathematical description was used, which was obtained from optical images and also by inspection of a representative sample of the microstructure that had been characterized by high‐resolution synchrotron XCT . A set of node positions in 3D space was first defined using the positions of centres along the fibre tows.…”

“…). Their arrangement is approximated in the FE model, using dimensions obtained from optical observations, which were consistent with previously obtained synchrotron tomography data . Each vertical fibre tow within a layer is defined using a two‐dimensional sinusoidal curve (Eq.…”

“…29 Because of the scale of the model required here to simulate the full specimen without using homogenization, a mathematical description was used, which was obtained from optical images and also by inspection of a representative sample of the microstructure that had been characterized by highresolution synchrotron XCT. 27 A set of node positions in 3D space was first defined using the positions of centres along the fibre tows. After defining this basic nodal set, the mesh of tetrahedral elements was created via Delaunay triangularization using the software PARAVIEW 3.98.…”