scholarly journals Synchrotron x-ray μ-tomography to model the thermal radiative properties of an opaque ceramic coating at T = 1000 K

2010 ◽  
Vol 25 (10) ◽  
pp. 1890-1897 ◽  
Author(s):  
B. Rousseau ◽  
H. Gomart ◽  
D. Zanghi ◽  
D. Bernard ◽  
M. Stampanoni
Keyword(s):  
Ceramic Coating ◽  
Geometrical Optic ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Radiative Properties ◽  
Surface Geometry ◽  
X Ray ◽  
Thermal Radiative Properties ◽  
Optic Approximation ◽  
Normal Emissivity

Synchrotron x-ray μ-tomography has been used to reconstruct the three-dimensional view of a rough surface extracted from a heterogeneous ceramic coating composed of Pr2NiO4+δ. Radiographs with a resolution of 0.7 μm have been recorded at T = 300, 600, and 900 K. The analysis of surface geometry makes use of the geometrical optic approximation up to T = 900 K possible. Subsequently, a large number of rays (105) are impinged onto the numerical surface, as revealed by x-ray tomography, to reproduce the normal emissivity of the coating. This normal emissivity was obtained beforehand by infrared emittance spectroscopy at T = 1000 K. Comparison of the two approaches suggests that the optical contribution of the coating micropores can be integrated into the ray tracing code. The effective medium approximation is used for this purpose. Finally, the applicability of this hybrid approach is discussed.

Prediction of the thermal radiative properties of an x-ray μ-tomographied porous silica glass

2007 ◽  
Vol 46 (20) ◽  
pp. 4266 ◽  
Author(s):  
Benoit Rousseau ◽  
Domingos de Sousa Meneses ◽  
Patrick Echegut ◽  
Marco Di Michiel ◽  
Jean-François Thovert
Keyword(s):  
Silica Glass ◽  
Porous Silica ◽  
Radiative Properties ◽  
X Ray ◽  
Thermal Radiative Properties ◽  
Porous Silica Glass

X-ray diffraction mapping on a curved surface

2011 ◽  
Vol 44 (6) ◽  
pp. 1211-1216 ◽  
Author(s):  
Masoud Allahkarami ◽  
Jay C. Hanan
Keyword(s):  
Three Dimensional ◽  
Complex Surface ◽  
Curved Surface ◽  
Zirconia Ceramic ◽  
X Ray Diffraction ◽  
Surface Geometry ◽  
X Ray ◽  
Fine Mesh ◽  
Alignment System ◽  
Mesh Grid

An efficient method for X-ray diffraction data collection mapping on a given curved surface has been developed. The method uses a laser–video autozalignment system to collect a map of heights on a fine mesh grid. It also reconstructs the surface geometry and determines surface normals on a three-dimensional surface fit. An algorithm was used to calculate the required rotation and tilt angles to coincide the sample normal with the diffraction center before each exposure. A set of diffraction frames collected using this technique was analyzed in order to superimpose a phase transformation map onto a typical zirconia ceramic sample. With this method, mapping of phase and stresses on a complex surface has been demonstrated. This approach is broadly applicable to many important areas of study.

Modelling the Mechanical and Thermal Properties of Cellular Materials from the Knowledge of their Architecture

2009 ◽  
Vol 1188 ◽  
Author(s):  
Eric Maire ◽  
O. Caty ◽  
R. Bouchet ◽  
M. Loretz ◽  
J. Adrien
Keyword(s):  
Computed Tomography ◽  
Thermal Properties ◽  
Cellular Materials ◽  
Radiative Properties ◽  
Mechanical And Thermal Properties ◽  
X Ray ◽  
Thermal Radiative Properties ◽  
X Ray Computed

AbstractThis paper shows different examples where the architecture of cellular materials has been determined exactly using 3D X ray computed tomography. The images were then subsequently used to generate FE meshes reproducing the architecture as exactly as possible. The FE meshes where in turn used to simulate the mechanical (monotonous and fatigue compression) and the thermal (radiative properties) behavior of the studied materials.

3D Numerical Prediction of Residual Stresses in Turning of 15-5PH

2011 ◽  
Vol 223 ◽  
pp. 411-420 ◽  
Author(s):  
Alexandre Mondelin ◽  
Frédéric Valiorgue ◽  
Joël Rech ◽  
Michel Coret ◽  
Eric Feulvarch
Keyword(s):  
Numerical Model ◽  
Residual Stresses ◽  
Martensitic Stainless Steel ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Significant Heterogeneity ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
X Ray ◽  
Chip Removal

This study presents the development of a numerical model for the prediction of residual stresses induced in finish turning of a 15-5PH martensitic stainless steel. This methodology uses a hybrid approach combining experimental results (friction and orthogonal friction tests) with a numerical model. The numerical model simulates the residual stresses generation by applying cyclic equivalent thermo-mechanical loads onto the machined surface without modeling the chip removal process. The three-dimensional approach enables to study the influence of the turning passes interactions. It has been shown numerically that the periodicity of loading leads to a significant heterogeneity of material solicitations. Moreover, overlapping of passes accentuates these effects. So, the model highlights the necessity of a multi-passes simulation to reach a constant evolution of residual stresses along the feed direction. In addition, experimental measurements obtained by X-Ray diffraction have been compared with numerical results to validate the model.

scholarly journals Crack Evolution and Oxidation Failure Mechanism of a SiC-Ceramic Coating Reactively Sintered on Carbon/Carbon Composites

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7780
Author(s):  
Min Xu ◽  
Lingjun Guo ◽  
Hanhui Wang
Keyword(s):  
Computed Tomography ◽  
Ceramic Coating ◽  
Three Dimensional ◽  
Carbon Composites ◽  
Self Healing ◽  
Internal Damage ◽  
X Ray ◽  
Heating And Cooling ◽  
Sic Ceramic ◽  
X Ray Computed

A SiC ceramic coating was prepared on carbon/carbon composites by pack cementation. The phase composition and microstructure of the coated specimens were characterized using X-ray diffraction instrument and scanning electron microscope. The results showed that the mass-loss percentage of the coated specimen was 9.5% after being oxidized for 20 h. The oxidation failure of the SiC ceramic coating at 1773 K was analysed by non-destructive X-ray computed tomography. The effective self-healing of cracks with widths below 12.7 μm introduced during the coating preparation process and generated while the specimens cooled down from the high oxidation temperature prevented the oxidation of carbon/carbon composites. X-ray computed tomography was used to obtain three-dimensional images revealing internal damage caused by spallation and open holes on the coating. Stress induced by heating and cooling caused the formation, growth and coalescence of cracks, which in turn led to exfoliation of the coating and subsequent failure of oxidation protection.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

X-ray microtomography

1988 ◽  
Vol 46 ◽  
pp. 998-999
Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico
Keyword(s):  
Computed Tomography ◽  
Internal Structure ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Tissue Structure ◽  
Individual Element ◽  
X Ray ◽  
Non Invasive ◽  
Panoramic Imaging ◽  
Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

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