Microstructure characterisation of ceramics via 2D and 3D X-ray refraction techniques

Kupsch, Andreas; Müller, Bernd R.; Lange, Axel; Bruno, Giovanni

doi:10.1016/j.jeurceramsoc.2016.12.031

Cited by 36 publications

(29 citation statements)

References 30 publications

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“…

C_{normalm} / μ

is proportional to the amount of inner surfaces that are perpendicular to the scattering vector. Thereby, a simultaneous decrease of

C_{normalm} / μ

in both sample orientations (TBC surface normal parallel and perpendicular to the scattering vector) means that the number of ‘objects’ is reduced, and those objects are either of spherical shape (pores) or of randomly distributed orientation . As mentioned above, in the as‐sprayed condition APS microstructures contain a reasonable amount of pores and cracks in the sub‐micrometer range.…”

Section: Resultsmentioning

confidence: 92%

“…Thereby, a simultaneous decrease of C m ∕ in both sample orientations (TBC surface normal parallel and perpendicular to the scattering vector) means that the number of 'objects' is reduced, and those objects are either of spherical shape (pores) or of randomly distributed orientation. 15 As mentioned above, in the as-sprayed condition APS microstructures contain a reasonable amount of pores and cracks in the sub-micrometer range. On operation at elevated temperatures, those features rapidly disappear due to sintering.…”

Section: X-ray Refractionmentioning

confidence: 85%

“…The refraction signal of an isotropic inhomogeneity, such as spherical voids, is present at any orientation of the specimen, whereas for cracks or elongated pores the signal vanishes when the defect surface normal is perpendicular to the scattering vector of the detection system. The X‐ray refraction signal has been quantitatively correlated to microstructural changes, which have been rationalized in micromechanical models …”

Section: Introductionmentioning

confidence: 99%

“…The X-ray refraction signal has been quantitatively correlated to microstructural changes, which have been rationalized in micromechanical models. 14,15 | 6165 MACK et Al.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of porosity, crack density, and CMAS penetration in thermal barrier coatings subjected to burner rig testing

et al. 2019

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Degradation of thermal barrier coatings (TBCs) in gas‐turbine engines due to calcium–magnesium–aluminosilicate (CMAS) glassy deposits from various sources has been a persistent issue since many years. In this study, state of the art electron microscopy was correlated with X‐ray refraction techniques to elucidate the intrusion of CMAS into the porous structure of atmospheric plasma sprayed (APS) TBCs and the formation and growth of cracks under thermal cycling in a burner rig. Results indicate that the sparse nature of the infiltration as well as kinetics in the burner rig are majorly influenced by the wetting behavior of the CMAS. Despite the obvious attack of CMAS on grain boundaries, the interaction of yttria‐stabilized zirconia (YSZ) with intruded CMAS has no immediate impact on structure and density of internal surfaces. At a later stage the formation of horizontal cracks is observed in a wider zone of the TBC layer.

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“…

C_{normalm} / μ

is proportional to the amount of inner surfaces that are perpendicular to the scattering vector. Thereby, a simultaneous decrease of

C_{normalm} / μ

Section: Resultsmentioning

confidence: 92%

Section: X-ray Refractionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

“…The X-ray refraction signal has been quantitatively correlated to microstructural changes, which have been rationalized in micromechanical models. 14,15 | 6165 MACK et Al.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evolution of porosity, crack density, and CMAS penetration in thermal barrier coatings subjected to burner rig testing

et al. 2019

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“…Apart from carrying an augmented information content, 3D data such as those from X-ray computed tomography, optical tomography or 3D infra-red thermography, allow the use of finite element simulations based on experimentally determined microstructures, or the extraction of quantitative data (e.g., fiber orientation distribution in concrete [ 18 ]) at the scale of a representative volume element (RVE). On top of that, in this Special Issue, the strength of a relatively novel technique, X-ray refraction radiography (see [ 19 ] for an introduction to it) was successfully used to quantify damage in thermally cycled refractory ceramics [ 20 ].…”

mentioning

confidence: 99%

Brittle Materials in Mechanical Extremes

Bruno

2020

Materials

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The goal of the Special Issue “Brittle Materials in Mechanical Extremes” was to spark a discussion of the analogies and the differences between different brittle materials, such as, for instance, ceramics and concrete. Indeed, the contributions to the Issue spanned from construction materials (asphalt and concrete) to structural ceramics, reaching as far as ice. The data shown in the issue were obtained by advanced microstructural techniques (microscopy, 3D imaging, etc.) and linked to mechanical properties (and their changes as a function of aging, composition, etc.). The description of the mechanical behavior of brittle materials under operational loads, for instance, concrete and ceramics under very high temperatures, offered an unconventional viewpoint on the behavior of brittle materials. This is not at all exhaustive, but a way to pave the road for intriguing and enriching comparisons.

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Evolution of Damage in All‐Oxide Ceramic Matrix Composite After Cyclic Loading

et al. 2021

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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.

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Microstructure characterisation of ceramics via 2D and 3D X-ray refraction techniques

Cited by 36 publications

References 30 publications

Evolution of porosity, crack density, and CMAS penetration in thermal barrier coatings subjected to burner rig testing

Evolution of porosity, crack density, and CMAS penetration in thermal barrier coatings subjected to burner rig testing

Brittle Materials in Mechanical Extremes

Evolution of Damage in All‐Oxide Ceramic Matrix Composite After Cyclic Loading

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