Photon CT scanning of advanced ceramic materials

Computed tomography (CT) using a high energy (1.25 MeV) photon source has been employed to image two specimens of sintered alumina ceramic. Because a monoenergetic source was used the absolute values of the densities could be measured to a high accuracy. High contrast (low noise) CT images were obtained permitting density measurement within each pixel to be determined with an accuracy of better than 1%. The average densities in regions encompassing several pixels have been determined with an accuracy of 0.2%. Porous regions and long-range density gradients were observed and quantified. Higher spatial resolution and still better contrast of the CT image could be obtained, however at the expense of the scan time. Good agreement was obtained for the two imaging techniques (CT and contact radiography), although both techniques showed slightly different features in the objects under study and therefore complement each other