13424 Delam Detection by Volumetric Xray Tomographic Imaging

One NDE method that can be used for delam detection that is quite independent of the thermal or physical properties or the geometric shape is X-ray computed tomographic (XCT) imaging. An example is of a 75-cm-diameter combustor liner made of CVI SiC/SiC. Figure 13.35 shows how the initial thermal diffusivity data, which suggested a delamination, were verified through use of volumetric XCT. In this case, the entire 20-cm-long section of the liner was imaged by XCT. Displaying the volumetric X-ray CT image in a high-end workstation with advanced three-dimensional image display allows the user to "onion peel" off layer by layer. Figure 13.35b shows that after "peeling" off four layers, the delam appears. Thus the XCT method not only allows detection but size and depth location as well.

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