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15 March 1996 Determining thermal diffusivity and defect attributes in ceramic matrix composites by infrared imaging
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Ceramic matrix composites are being developed for numerous high temperature applications, including rotors and combustors for advanced turbine engines, heat exchanger and hot-gas filters for coal gasification plants. Among the materials of interest are silicon-carbide-fiber- reinforced-silicon-carbide (SiC(f)/SiC), silicon-carbide-fiber-reinforced-silicon-nitride (SiC(f)/Si3N4), aluminum-oxide-reinforced-alumina (Al2O3(f)/Al2O3, etc. In the manufacturing of these ceramic composites, the conditions of the fiber/matrix interface are critical to the mechanical and thermal behavior of the component. Defects such as delaminations and non-uniform porosity can directly affect the performance. A nondestructive evaluation (NDE) method, developed at Argonne National Laboratory has proved beneficial in analyzing as-processed conditions and defect detection created during manufacturing. This NDE method uses infrared thermal imaging for full-field quantitative measurement of the distribution of thermal diffusivity in large components. Intensity transform algorithms have been used for contrast enhancement of the output image. Nonuniformity correction and automatic gain control are used to dynamically optimize video contrast and brightness, providing additional resolution in the acquired images. Digital filtering, interpolation, and least-squares-estimation techniques have been incorporated for noise reduction and data acquisition. The Argonne NDE system has been utilized to determine thermal shock damage, density variations, and variations in fiber coating in a full array of test specimens.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sanjay Ahuja, William A. Ellingson, J. B. Stuckey, and E. R. Koehl "Determining thermal diffusivity and defect attributes in ceramic matrix composites by infrared imaging", Proc. SPIE 2766, Thermosense XVIII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications, (15 March 1996);

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