Functionally Graded Porosity in Ceramics ‐ Analysis with High Resolution Computed Tomography

The characterization of graded materials requires methods mapping local varying properties of materials. One of the most useful tools is high-resolution computed tomography. The ability to view inside the samples could beused to determine several features like density variation, porosity distribution and other structural parameters. With one of the two 3D-tomographs developed at BAM, a spatial resolution of about 2 μm can be reached dependent of the object diameter. As radiation source, a micro focus X-ray tube with a transmission target is used together with a cooled CCD camera and a fiber optic coated with a thin scintillate layer. Ceramic membranes with capillary pores (e.g. Hydroxylapatite, TiO 2 ) are analyzed with CT and image processing. Beside the variation of pore diameter, which are in the range of 3 to 30 pm, the throughput of the capillaries and their structure was measured and analyzed.