In this paper the characterisation of functionally graded materials is elucidated by several different methods. These methods described here are used for the quantitative analysis of materials with a local dependence of microstructure parameters. Using X-ray microscopy (computed tomography) for 3D-measurements and optical microscopy on polished sections for 1D and 2D measurements on the same sample, a ceramic filter consisting of sintered spherical particles, various mathematical evaluation methods are described and compared.
The use of high brilliance and partial coherent synchrotron light for radiography and computed tomography (CT) allows to image micro-structured, multi-component specimens with different contrast modes and resolutions up to submicrometer range. This is of high interest for materials research, life science and non-destructive evaluation applications. An imaging setup for microtomography and radiography installed at BESSY II (a third generation synchrotron light source located in Berlin, Germany) as part of its first hard X-ray beamline (BAMline) can now be used for absorption, refraction as well as phase contrast dedicated to inhouse research and applications by external users. Monochromatic synchrotron light between 6 keV and 80 keV is attained via a fully automated double multilayer monochromator. For imaging applications the synchrotron beam transmitted by the sample is converted with a scintillator into visible light. By use of microscope optics this luminescence image is then projected onto, e.g., a CCD chip. Several scintillating materials are used in order to optimise the performance of the detector system. Different optical systems are available for imaging ranging from a larger field of view and moderate resolutions (macroscope up to 14 mm x 14 mm field of view) to high resolution (microscope down to 0.35 μm pixel size), offering magnifications from 1.8× to 40×. Additionally asymmetric cut Bragg crystals in front of the scintillator can be used for a further magnification in one dimension by a factor of about 20. Slow and fast cameras are available, with up to 16 bit dynamic range. We show the suitability of the setup for numerous applications from materials research and life science.
By means of synchrotron X-ray computed tomography, model composites consisting of silica and styrenebutadiene rubber were studied with a very high spatial resolution. By our analysis technique we were able to determine the nano- and micro dispersion from the experimental results by our numerical analysis. These results are discussed with respect to crucial advantages of the generically 3-dimensional tomography technique as compared to 2-dimensional methods. Our quantitative analysis of the 3d images demonstrates that in the case of our model composites the filler dispersion is good, independent on the filler concentration. Our new 3-dimensional results evidence that considering only 2-d pictures may lead to ambiguities that can lead to wrong conclusions.