Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (31) (entfernen)
Sprache
- Englisch (31)
Schlagworte
- X-ray refraction (16)
- Computed tomography (5)
- Additive manufacturing (3)
- Microcracking (3)
- Pore orientation (3)
- Porosity (3)
- Synchrotron X-ray refraction radiography (3)
- BAMline (2)
- Chaboche model (2)
- Creep (2)
- Damage (2)
- Diffraction Enhanced Imaging (2)
- GTN model (2)
- Metal matrix composites (2)
- Microscopy (2)
- Porous ceramics (2)
- Refraction (2)
- Selective laser melting (2)
- Synchrotron (2)
- Synchrotron radiation (2)
- X-Ray Refraction (2)
- X-ray computed tomography (2)
- X-ray imaging (2)
- 2101 duplex stainless steel (1)
- 3D microstructure (1)
- 3D printing (1)
- 3D printing Polyamide 12 (1)
- Additive manufacturing (AM) (1)
- AlSi10Mg alloy (1)
- Aluminium alloys (1)
- Analyzer-Based Imaging (1)
- Beta-eucryptite (1)
- CMAS (1)
- CT (1)
- Carbon Fiber Reinforced Plastics (1)
- Cavitation (1)
- Ceramic matrix composite (1)
- Ceramic matrix composites (1)
- Ceria (1)
- Characterization (1)
- Composite materials (1)
- Composites (1)
- Computed Tomography (1)
- Crack detection (1)
- Crack evolution (1)
- Crystal Texture (1)
- Crystal structure (1)
- DIVA Algorithm (1)
- Damage evolution (1)
- Defects (1)
- Delamination (1)
- Diesel Fuel (1)
- Diesel Particulate Filter Materials (1)
- Diesel particulate filters (1)
- Electro-fused zirconia (1)
- Electron microscopy (1)
- Extrusion (1)
- Fe2TiO5 (1)
- Fiber de-bonding (1)
- Glass-ceramic (1)
- Grating interferometry (1)
- Homogenization schemes (1)
- Hydrogen embrittlement (1)
- Hystersis (1)
- INCONEL 718 (1)
- Impurity segregation (1)
- In situ tensile test (1)
- Interface (1)
- Internal Surfaces (1)
- Laser powder bed fusion (LPBF) (1)
- Material and damage behaviour (1)
- Material science (1)
- Micro analysis (1)
- Microcracked ceramics (1)
- Microstructure (1)
- Microstructure-property relations (1)
- Non-Destructive Evaluation (1)
- Nonlinear behavior (1)
- Nonlinear stress-strain curve (1)
- PE-HD Sorption (1)
- Phase grating (1)
- Phase transformation (1)
- Plasticity (1)
- Polyamide 12 (1)
- Pore Orientation (1)
- Porous Ceramics (1)
- Preferred orientation (1)
- Pseudo-Voigt fit function (1)
- Python (1)
- Radiography (1)
- Refractory (1)
- Scanning transmission electron microscopy (1)
- Si network disintegration (1)
- Specific surface (1)
- Statistically relevant volumes (1)
- Stiffness (1)
- Strain hardening (1)
- Synchrotron Radiation (1)
- Synchrotron X-ray refraction (1)
- Synchrotron X‐ray refraction radiography (1)
- Synchrotron imaging (1)
- Synchrotron x-ray refraction radiography (SXRR) (1)
- Synchrotron, BAMline (1)
- Talbot-Lau interferometer (1)
- Talbot-Lau interferometry (1)
- Tensile load (1)
- Thermal barrier coatings (1)
- Thermal expansion (1)
- Thermally induced porosity (TIP) (1)
- Thermoelectrics (1)
- Tomography (1)
- Viscoplastic (1)
- Visibility (1)
- WAXS (1)
- X-Ray Computed Tomography (1)
- X-ray (1)
- X-ray phase contrast (1)
- X-ray reefraction (1)
- X-ray refraction radiography (1)
- Zirconia (1)
- subgrain structure (1)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (24)
- 8.5 Röntgenbildgebung (24)
- 5 Werkstofftechnik (3)
- 5.3 Polymere Verbundwerkstoffe (2)
- 6 Materialchemie (2)
- 5.4 Multimateriale Fertigungsprozesse (1)
- 6.1 Oberflächen- und Dünnschichtanalyse (1)
- 6.3 Strukturanalytik (1)
- 7 Bauwerkssicherheit (1)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (1)
Paper des Monats
- ja (1)
Evaluating porosity in cordierite diesel particulate filter materials, part 1 X-ray refraction
(2013)
Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, with porosity and solid matter being intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using x-ray absorption and refraction, we quantitatively evaluate porosity and pore orientation in cordierite diesel particulate filter ceramics. Porosity values turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data.
While the problem of the identification of mechanisms of hydrogen assisted damage has and is being thoroughly studied, the quantitative analysis of such damage still lacks suitable tools. In fact, while, for instance, electron microscopy yields excellent characterization, the quantitative analysis of damage requires at the same time large field-of-views and high spatial resolution. Synchrotron X-ray refraction techniques do possess both features. In this work, we show how synchrotron X-ray refraction computed tomography (SXRCT) can quantify damage induced by hydrogen embrittlement in a lean duplex steel, yielding results that overperform even those achievable by synchrotron X-ray absorption computed tomography. As already reported in literature, but this time using a non-destructive technique, we show that the hydrogen charge does not penetrate to the center of tensile specimens. By the comparison between virgin and hydrogen-charged specimens, we deduce that cracks in the specimen bulk are due to the rolling process rather than hydrogen-assisted. We show that (micro)cracks propagate from the surface of tensile specimens to the interior with increasing applied strain, and we deduce that a significant crack propagation can only be observed short before rupture.
For the first time, synchrotron X-ray refraction radiography (SXRR) has been paired with in-situ heat treatment to monitor microstructure and porosity evolution as a function of temperature. The investigated material was a laser powder bed fusion (LPBF) manufactured AlSi10Mg, where the initial eutectic Si network is known to disintegrate and spherodize into larger particles with increasing temperature. Such alloy is also prone to thermally induced porosity (TIP). We show that SXRR allows detecting the changes in the Si-phase morphology upon heating, while this is currently possible only using scanning electron microscopy. SXRR also allows observing the growth of pores, usually studied via X-ray computed tomography, but on much smaller fields-of-view. Our results show the great potential of in-situ SXRR as a tool to gain in-depth knowledge of the susceptibility of any material to thermally induced damage and/or microstructure evolution over statistically relevant volumes.
The determination of the anisotropy of materials’ microstructure and morphology (pore space) in diesel particulate filter (DPF) materials is an important problem to solve, since such anisotropy determines the mechanical, thermal, and filtration properties of such materials. Through the use of a dedicated (and simple) segmentation algorithm, it is shown how to exploit the information yielded by 3D X-ray computed tomography data to quantify the morphological anisotropy. It is also correlated that such anisotropy of the pore space Such anisotropy of the pore space is also correlated with the microstructure and crystallographic anisotropy of the material in several showcases: a microstructurally isotropic material, such as SiC, and some morphologically and microstructurally anisotropic cordierite materials. In the later case, the finer the grain size, the more isotropic the microstructure.
While structural ceramics usually display a brittle mechanical behavior, their composites may show nonlinearities, mostly due to microcracking. Herein, the stiffness evolution of a sandwich-like laminate of an Al2O3 15%vol. ZrO2 matrix reinforced with Nextel 610 fibers is studied as a function of number of cycles N in tension. The stiffness of the composite degrades with increasing N, indicating microcracking. However, synchrotron X-ray refraction radiography shows that the internal specific surface of such cracks varies differently. A modeling strategy is developed for the calculation of the equivalent stiffness of mixtures (first the matrix and then the sandwich), based on the Voigt and Reuß schemes. The Bruno–Kachanov model is then used to estimate the initial microcrack density in the matrix (due to the thermal expansion mismatch) and the amount of microcracking increase upon cyclic loading. The stiffness in the composite degrades dramatically already after 20 000 cycles but then remains nearly constant. The combination of mechanical testing, quantitative imaging analysis, and modeling provides insights into the damage mechanisms acting: microcrack propagation is more active than microcrack initiation upon cyclic loading, but the second also occurs. This scenario is similar but not equal to previous results on porous and microcracked ceramics.
Diffraction enhanced imaging (DEI) is an advanced digital radiographic imaging technique employing the refraction of X-rays to contrast internal interfaces. This study aims at qualitatively and quantitatively evaluating images acquired using this technique and to assess how different fitting functions to the typical rocking curves (RCs) influence the quality of images. RCs are obtained for every image pixel. This allows the separate determination of the absorption and the refraction properties of the material in a position-sensitive manner. Comparison of various types of fitting functions reveals that the Pseudo-Voigt (PsdV) function is best suited to fit typical RCs. A robust algorithm was developed in the Python programming language, which reliably extracts the physically meaningful information from each pixel of the image. We demonstrate the potential of the algorithm with two specimens: a silicone gel specimen that has well-defined interfaces, and an additively manufactured polycarbonate specimen.
Complementary to Part 1 of this work, the bi-continuous microstructure of porous synthetic cordierite ceramics for filtration applications was investigated using 3D x-ray computed tomography at different resolutions. Applying both Fast Fourier Transform and a newly developed image analysis algorithm, we quantitatively evaluated porosity and pore orientation. The statistical approach allows extraction of spatially resolved or average values. Porosity values based on x-ray absorption agree with mercury intrusion measurements, while pore orientation factors agree with x-ray refraction data (Part 1 of this work), and with published crystallographic texture data.
Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, whereby porosity and solid matter are intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using 3D computed tomography (CT) at different resolutions, and several X-ray refraction-based techniques, we quantitatively evaluated porosity and pore orientation in cordierite diesel particulate filter ceramics.Moreover, applying both Fast Fourier Transform (FFT) and a newly developed image analysis algorithm (directional interface variance analysis, DIVA), we quantitatively evaluated porosity and pore orientation. Both the experimental techniques and the statistical approach allow extraction of spatially resolved or average values.Porosity values from synchrotron computed tomography used turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data. This latter point also implies that the study of the pore/matter interface is sufficient to describe the morphological properties of these materials.
Talbot-Lau interferometry provides X-ray imaging techniques with significant enhancement of the radiographic contrast of weakly absorbing objects. The grating based technique allows separation of absorption, refraction and small angle scattering effects. The different efficiency of rectangular and triangular shaped phase gratings at varying detector distances is investigated. The interference patterns (Talbot carpets) are modeled for parallel monochromatic radiation and measured by synchrotron radiation. In comparison to rectangular shapes of phase gratings much higher visibility is obtained for triangular shapes which yield enhanced contrast of a glass capillary test specimen.
X-ray refraction is based on optical deflection of X-rays, similar to the well-known small angle X-ray scattering, but hundreds of times more intense, thus enabling shorter measurement time. We show that X-ray refraction techniques are suitable for the detection of pores, cracks, and in general defects. Indeed, the deflected X-ray intensity is directly proportional to the internal specific surface (i.e., surface per unit volume) of the objects. Although single defects cannot be imaged, the presence of populations of those defects can be detected even if the defects have sizes in the nanometer range.We present several applications of X-ray refraction techniques to composite materials:- To visualize macro and microcracks in Ti-SiC metal matrix composites (MMC);- To correlate fatigue damage (fibre de-bonding) of carbon fibre reinforced plastics (CFRP) to X-ray refraction intensity;- To quantify the impact damage by spatially resolved single fibre de-bonding fraction as a function of impact energy in CFRP laminates.An example of classic high-resolution computer tomography of an impact-damaged CFRP will also be presented, as a benchmark to the present state-of-the-art imaging capabilities. It will be shown that while (absorption) tomography can well visualize and quantify delamination, X-ray refraction techniques directly yield (spatially resolved) quantitative information about fibre de-bonding, inaccessible to absorption tomography.