Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (67)
- Beitrag zu einem Tagungsband (52)
- Beitrag zu einem Sammelband (45)
- Vortrag (34)
- Sonstiges (7)
- Posterpräsentation (6)
- Buchkapitel (3)
Schlagworte
- Computed tomography (25)
- X-ray refraction (19)
- Reconstruction algorithm (12)
- Computer-Tomographie (10)
- DIRECTT (8)
- Electron tomography (8)
- Rekonstruktionsalgorithmen (8)
- Computertomographie (7)
- Keramik (6)
- Synchrotron radiation (6)
- Composites (5)
- Radiography (5)
- Refraction (5)
- Tomography (5)
- Catalyst (4)
- Ceramics (4)
- Computed Tomography (4)
- Diffuse background (4)
- Fluorescent screen (4)
- Fuel cell (4)
- Komposite (4)
- Missing wedge (4)
- Neutron tomography (4)
- Neutronen-Tomographie (4)
- Phase contrast (4)
- Pore size (4)
- Porous ceramics (4)
- Röntgenrefraktion (4)
- Synchrotron (4)
- X-ray refraction topography (4)
- Aerospace (3)
- Computertomographie (CT) (3)
- Elektronen-Tomographie (3)
- Explosivstoffe (3)
- Hinterleuchten (3)
- Iterative reconstruction (3)
- Limited view (3)
- Materialcharakterisierung (3)
- NDE (3)
- Non-destructive testing (3)
- Polymer electrolyte membrane fuel cell (PEMFC) (3)
- Pore orientation (3)
- Porosity (3)
- Rekonstruktionsalgorithmus (3)
- Röntgen-Refraktions-Topographie (3)
- Soft matter radiography (3)
- Statistische Bewertung (3)
- Synchrotron Radiation (3)
- WAXS (3)
- X-ray (3)
- X-ray Refraction (3)
- X-ray detector backlighting (3)
- X-ray tomography (3)
- X-ray topography (3)
- BAMline (2)
- Bragg magnification (2)
- Cartilage (2)
- Characterization (2)
- Computed Tomography (CT) (2)
- DEI (2)
- Diesel particulate filters (2)
- Diffraction Enhanced Imaging (DEI) (2)
- Diffraction enhanced imaging (2)
- Edge artefact (2)
- Elektronentomographie (2)
- Explosives (2)
- Fluoreszenzschirm (2)
- Foams (2)
- Focal smearing (2)
- Gas diffusion layer (GDL) (2)
- Grating interferometry (2)
- Huygens elementary waves (2)
- Iterative Rekonstruktion (2)
- Kleinwinkelstreuung (2)
- Lightweight Materials (2)
- Lightweight materials (2)
- MMC (2)
- Magnetic domains (2)
- Metal Matrix Composites (MMC) (2)
- Metal matrix composites (2)
- Neutron imaging (2)
- Neutronentomographie (2)
- Nichtmetallische Werkstoffe (2)
- Non-Destructive Inspection (NDI) (2)
- Ortsauflösung (2)
- PEM fuel cell (2)
- Radiographie (2)
- Refraction enhanced imaging (REI) (2)
- Refraction topography (2)
- Region of interest (2)
- Röntgen-Streuung (2)
- Röntgendetektor (2)
- Röntgentomographie (2)
- Spatial resolution (2)
- Specific surface (2)
- Synchrotron Refraction CT (2)
- Synchrotron refraction computed tomography (2)
- Synchrotronstrahlung (2)
- Terahertz-Radiographie (2)
- Ti-MMC (2)
- Tomographische Rekonstruktionsalgorithmen (2)
- Topography (2)
- Water management (2)
- X-Ray Refraction (2)
- X-ray compton scattering (2)
- X-ray refraction tomography (2)
- X-ray scattering (2)
- 3D microstructure (1)
- 3D topography (1)
- 3D-Mikrostruktur (1)
- Advanced Composite (1)
- Advanced ceramics (1)
- Al2O3 ceramics (1)
- Algorithm (1)
- Analyser based imaging (1)
- Analyser-based imaging (1)
- Analyzer based imaging (1)
- Average pore size (1)
- Backlight (1)
- Beta-eucryptite (1)
- Beton (1)
- Bildgebende Radiologie (1)
- Bildgebende Röntgenverfahren (1)
- Bragg Magnification (1)
- Bragg-Magnification (1)
- Bragg-Vergrößerung (1)
- Brennfleck (1)
- Brennstoffzelle (1)
- Brennstoffzellen (1)
- C/C Keramiken (1)
- CFK (1)
- CFRP (1)
- CT (1)
- CT-Algorithmus (1)
- Cavitation (1)
- Coherent imaging (1)
- Complex microstructure (1)
- Composite damaging (1)
- Compounds (1)
- Compression device (1)
- Comptonstreuung (1)
- Computed topography (1)
- Computer Tomographie (1)
- Computer tomography (1)
- Computerised tomography (1)
- Computertomografie (1)
- Concrete (1)
- Cordierit (1)
- Crack Density (1)
- Crack density (1)
- Crystal Texture (1)
- DIVA Algorithm (1)
- DIVA algorithm (1)
- Darkfield imaging (1)
- Detector backlighting (1)
- Detector calibration (1)
- Detektor (1)
- Diesel Fuel (1)
- Diffraktion (1)
- Double-Crystal-Monochromator with sagittal bender (1)
- Double-Multilayer-Monochromator with meridional bender (1)
- Dual Energy (1)
- Dunkelfeldabbildung (1)
- Electronic Power Device IC (1)
- Ermüdung (1)
- Ermüdungsrisse (1)
- FAXOT (1)
- Fatigue (1)
- Few angles (1)
- Fibre Debonding (1)
- Fibre orientation (1)
- Filtering (1)
- Fluorescence screen (1)
- Fuel cell stack (1)
- Gefilterte Rückprojektion (1)
- Geometrical tortuosity (1)
- High pressure mercury intrusion (1)
- Hochleistungswerkstoffe (1)
- Holotomography (1)
- Image morphology (1)
- Impact (1)
- In-Situ Radiologie (1)
- Inhomogeneous materials (1)
- Inner surface (1)
- Inner surface density (1)
- Interface (1)
- Interfaces (1)
- Internal Surfaces (1)
- Internal surface density (1)
- Iterative CT reconstruction (1)
- Konvergenz (1)
- Kurzzeit-Radiometrie (1)
- Limited View (1)
- Limited tomographic data (1)
- Manifold stack (1)
- Materialcharakterisierung und -identifizierung (1)
- Mehrphasige Materialien (1)
- Mercury intrusion porosimetry (1)
- Metal Matrix Composites (1)
- Metal matrix composite (MMC) (1)
- Metrology (1)
- Micro cracks (1)
- Micro-CT (1)
- Micro-computed tomography (1)
- Microcracked ceramics (1)
- Microstructure (1)
- Microstructures (1)
- Microtomography (1)
- Mikroriß (1)
- Missing Wedge (1)
- Modulations-Transfer-Funktion (1)
- Modulations-Transfer-Funktion (MTF) (1)
- Molecular probe (1)
- Monochromatische Radiometrie (1)
- Montmorillonites (1)
- Morphological image analysis (1)
- Multiple View Inspection (1)
- Nanocomposites (1)
- Nanocracks (1)
- Nanostructures (1)
- Nanostrukturen (1)
- Neues Prinzip der computer-tomographischen Rekonstruktion ohne Fourier-Filterung (1)
- Neutron computed tomography (1)
- Neutronen-Radiographie (1)
- Neutrons (1)
- Non-destructive evaluation (1)
- Non-metallics (1)
- Nondestructive characterization (1)
- Nondestructive materials characterisation (1)
- Nondestructive testing (1)
- Oberfläche, innen (1)
- Opacity (1)
- Oxidative Schädigung (1)
- PE-HD Sorption (1)
- Phase boundary (1)
- Phase contrast radiography (1)
- Phase grating (1)
- Phase-contrast X-ray imaging (1)
- Polymers (1)
- Polypropylene-graft-maleic anhydride (1)
- Pore Orientation (1)
- Pore Size (1)
- Pore size analysis (1)
- Porengröße (1)
- Porenorientierung (1)
- Porosity fluctuation (1)
- Porous Ceramics (1)
- Poröse Keramik (1)
- Quantitative image analysis (1)
- Quenching (1)
- Radiology (1)
- Reconstruction (1)
- Reconstruction algorithms (1)
- Reconstruction algrorithm (1)
- Reflectometry (1)
- Refraktion (1)
- Refraktionskontrast (1)
- Refraktionstopographie (1)
- Rekristallisation (1)
- Renewable energy (1)
- Rissdichte (1)
- Risse (1)
- Röntgen-Diffraktions-Mikroskopie (1)
- Röntgen-Kanten-Tomographie (1)
- Röntgen-Refraktion (1)
- Röntgen-Refraktions-Computer-Tomographie (1)
- Röntgen-Szintillationsdetektor hoher Zählraten (1)
- Röntgen-Topographie (1)
- Röntgen-Topographie und -Streuung (1)
- Röntgenstreuverfahren (1)
- SAXS (1)
- SCS6 (1)
- SRCT (1)
- Scanning transmission electron microscopy (STEM) (1)
- Schlagfestigkeit (1)
- Scintillator (1)
- Shearing gratings (1)
- Small angle scattering (1)
- Spatial reslution (1)
- Spatial statistics (1)
- Specific surface area (1)
- Spectral computed tomography (1)
- Statistical analysis (1)
- Strain hardening (1)
- Stromdichtemessung (1)
- Structural (1)
- Structure property relations (1)
- Surface density (1)
- Synchrotron Laue Contrast Radiography (1)
- Synchrotron Laue Contrast Radiography SLCR (1)
- Synchrotron X-ray tomography (1)
- Synchrotron instrumentation (1)
- Synchrotron radiography (1)
- Synchrotron, BAMline (1)
- Synchrotron-CT (1)
- Synchrotron-Radiographie (1)
- Talbot- Lau interferometry (1)
- Talbot-Lau (1)
- Talbot-Lau interferometer (1)
- Talbot-Lau neutron tomography (1)
- Tensile load (1)
- Terahertz Imaging (1)
- Terahertz time domain spectroscopy (1)
- Terahertz-Radiography (1)
- Texture (1)
- Thermal stability (1)
- Thermoplaste (1)
- Threat Detection (1)
- Three-dimensional data quantification (1)
- Ti6242 (1)
- Titanium Metal Matrix Composites (Ti-MMC) (1)
- Tomographic reconstruction (1)
- Tomographische Rekonstruktions-Algorithmen (1)
- Tortuosity (1)
- USAXS (1)
- Verbundwerkstoff (1)
- Vergrößerung mit asymmetrischen Kristallen (1)
- Verschmierung (1)
- Visibility (1)
- Wassermanagement (1)
- Water transport path (1)
- Wavelet transform (1)
- Wavelet transformation (1)
- Wide angle X-ray scattering (1)
- X-Ray Computed Tomography (1)
- X-ray absorption and refraction CT (1)
- X-ray computed tomography (1)
- X-ray detector (1)
- X-ray detector scattering (1)
- X-ray diffraction (1)
- X-ray diffraction microscopy (1)
- X-ray fluorescence analysis (1)
- X-ray imaging (1)
- X-ray microscopy (1)
- X-ray phase contrast (1)
- X-ray refractometry (1)
- X-ray scattering topography (1)
- XROT (1)
- Zerstörungsfrei (1)
- Zerstörungsfreie Materialcharakterisierung (1)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (34)
For the first time Metal Matrix Composites (MMC) have been investigated by 3D Computed Tomography combined with enhanced interface contrast due to X-ray refraction. X-ray refraction is a relatively new approach for the characterization of advanced materials. The related techniques of Refraction Topography and Refraction Computed Tomography have been developed and applied at our laboratory during the last decade to meet the actual demand for improved nondestructive characterization of high performance composites, ceramics and other low density materials and components. X-ray refraction occurs, when X-rays crosses interfaces of spherical or cylindrical shape (e.g. pores or fibres) in the same way as visible light is refracted by lenses. These X-ray optical effects can be observed at small scattering angles of few minutes of arc as the refractive index n of X-rays is nearly unity (n = 1 10-6). Due to the short X-ray wavelength of about 0.1 nm the technique determines the amount of inner surfaces and interfaces of nanometer dimensions. The technique is expected to solve many problems in understanding the meaning of micro and sub micro structures in materials science. With the results of the CT investigation, some questions could be clarified for a better understanding of fatigue failure mechanisms under cyclic loading conditions. The specimens for the test programme have been provided by MTU Aero Engines. They consist of a titanium matrix (Ti6242) reinforced by SiC fibres (SCS6). The investigations have been performed at the materials research station of BAM (BAMline) at the Synchrotron Facility BESSY in Berlin, Germany.
A novel approach is suggested to strongly suppress artifacts in radiography and computed tomography caused by the effect of diffuse background signals 'backlighting' of 2D X-ray detectors. Depending on the detector geometry the mechanism may be different. Either based on the optical scattering of the fluorescent screen materials into the optical detection devices or Compton or X-ray fluorescence scattering by the detector components. Consequently, these erroneous intensity portions result in locally different violations of Lambert Beer's law in single projections (radiographs) as a function of the detector area coverage and the magnitude of the attenuation. The absorption of multiple metal sheets is investigated by monochromatic synchrotron radiation, thus excluding beam hardening. The proposed correction procedure simply requires the individual subtraction of one and the same fraction of the primary and transmitted mean intensity, as a constant (non-local) scattering mechanism is assumed.
We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell.
Analyser-based imaging expands the performance of X-ray imaging by utilizing not only the absorption properties of X-rays but also the refraction and scatter rejection (extinction) properties. In this study, analyser-based computed tomography has been implemented on imaging an articular cartilage sample, depicting substructural variations, without overlay, at a pixel resolution of 3.6 µm.
Tomography data obtained from transmission electron microscopes are especially attractive due to their unrivaled spatial resolution in the nanometer range or even less, but they require enormous efforts in sample preparation and suffer from a diverse accumulation of experimental restrictions, which unavoidably result in fundamental reconstruction artifacts. These restrictions refer to: partial opacity, a limited view (limited angle or missing wedge), very few angles (with respect to the detector size), limited to a region of interest (ROI; due to the sample size), variable angular increments as well as sample degradation due the interactions with the electron beam. An advanced version of the DIRECTT (Direct Iterative Reconstruction of Computed Tomography Trajectories) algorithm proves to cope with most of these severe deviations from ideal CT measuring conditions. However, careful data preprocessing is required in order to exploit the capabilities of the algorithm.
Nanometer sized Ruthenium catalyst particles for fuel cell applications are 3D imaged at a few Ångström resolution in order to estimate their partial free surface on carbon black supports, which rule the efficiency of the catalytic activity.
Comparisons of DIRECTT reconstructions to the conventional filtered back projection, prove the significant improvements.
The first hard X-ray beamline at BESSY II will be installed by BAM and PTB at a superconducting 7 T wavelength shifter. The main optical elements of the beamline are a Double-Multilayer-Monochromator and a Double-Crystal-Monochromator. The two devices can be used separately or in-line. Main applications of monochromatic radiation with photon energies up to 50 keV are X-ray fluorescence analysis, micro-computed tomography, X-ray topography, detector calibration and reflectometry. Calculable undispersed radiation up to 200 keV will be available for radiometric applications.
Modellrechnungen mit dem CT-Algorithmus DIRECTT (Direkte iterative Rekonstruktion computertomographischer Trajektorien) haben die Vorteile gegenüber anderen Ansätzen bezüglich Ortsauflösung und Dichte gezeigt, insbesondere auch für unvollständige Datensätze wie Limited View- und Region of Interest-Szenarien. Entsprechend dem Normalfall werden hier jedoch vollständige Datensätze von Modellen und Messungen und ihre Rekonstruktionen bewertet. Die Qualität von DIRECTT wird mit der Gefilterten Rückprojektion anhand der Modulations-Transfer-Funktion (MTF) sowie integraler Kenngrößen im Radon- und im Ortsraum verglichen. Zur Überprüfung der Rekonstruktionsgenauigkeit experimenteller Daten werden Mustermessungen einfacher Probengeometrien unter definierten physikalischen Bedingungen durchgeführt. Diese betreffen Monochromasie, Unterdrückung von Kantenartefakten und radiometrische Intensitätsbestimmung mit Einkanaldetektor.
Bikontinuierliche poröse Keramiken für Filteranwendungen weisen eine komplizierte Mikrostruktur auf, in der Poren und Festkörperphase 'vermischt' sind. Mechanische, thermische sowie Filtereigenschaften können nur präzise bestimmt werden, wenn die Morphologie beider Phasen quantitativ angegeben werden kann. Hier werden unter Anwendung von 3D Computertomographie (CT) und verschiedenen Techniken, die auf der Röntgenrefraktion basieren, die Porosität und die Porenorientierung in keramischen Cordierit-Dieselpartikelfiltern bewertet. Dabei werden zur Auswertung der Tomogramme die Fouriertransformierten sowie eine neu entwickelte richtungssensitive Bildanalyse (DIVA, directional interface variance analysis) angewandt. Sowohl die genannten Messtechniken als auch der statistische Ansatz gestatten die Extraktion optional ortsaufgelöster oder gemittelter Werte. Es ergeben sich sehr gute Übereinstimmungen der experimentell ermittelten Porositätswerte mit Ergebnissen aus Quecksilberintrusionsversuchen als auch der ermittelten Porenorientierung im Vergleich zu publizierten Angaben zur kristallographischen Textur. Dies legt den Schluss nahe, dass die Kenntnis der Grenzflächen (zwischen Poren und Materie) genügt, die morphologischen Eigenschaften solcher Materialien hinreichend zu beschreiben.
C-fibre degradation debonding and lamella buckling measurement in CMC by new X-ray topography
(1993)
Aiming at ceramic materials of low thermal radiation emittance titania yttrium oxide ceramics have been prepared by sintering in air at 1,100 and 1,400 °C, respectively, and characterised. Due to its high infrared refractive index, average pore sizes up to 1 µm for optimal Mie scattering cross sections and over 35% porosity the material is a promising candidate for elevated temperature insulations. The essentially in large pore growth is achieved by graphitic nano and micro particle additives.
The microstructure parameters of porosity, specific surface area, median and average pore sizes are determined by mercury intrusion porosimetry. Beyond this classical technique supplementary measurements by X-ray Absorption and X-ray refractometry reveal considerably larger average pore sizes due to closed pores not accessible for mercury. An additional advantage of the X-ray techniques is their non-destructive application, which allows other treatments afterwards. The combined application of both methods provides additional information and reliability in case of complex ceramic microstructures and may serve for improved developments of porous ceramics with optimised thermal scattering for energy savings in high temperature applications.