Determination of preferred orientation textures in Al2O3 ceramics

Böcker, A.; Brokmeier, H.-G.; Bunge, H. J.

doi:10.1016/0955-2219(91)90074-a

Cited by 16 publications

(6 citation statements)

References 4 publications

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“…While the "random" samples have the correct amount of liquid phase and densities and grain sizes similar to those of the textured materials, they may be slightly textured, as has been demonstrated for several substrate materials. 22 Examination of the "random" samples by Rietveld methods, and also by rocking curve analysis using 112 3, 112 6, and 303 0 peaks, revealed minimal texture out to the angles accessible by the rocking curve technique, but as demonstrated by Böcker et al 23 evaluation of weak basal plane texture in alumina can require pole figure measurements of several peaks, because the intensities of basal plane peaks from alumina (0006 and 000.12) are intrinsically weak. The textured alumina specimens in this study produced 000.12 peaks of significant intensity, so that a single pole figure was adequate for measuring axisymmetric texture about the (0001) pole; however, the 000.12 intensity from the "random" specimen was very low, making the pole figure correction factor susceptible to noise and background errors, as discussed above.…”

Section: Discussionmentioning

confidence: 97%

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al₂O₃

Seabaugh

Vaudin

Cline

et al. 2000

Journal of the American Ceramic Society

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Texture measurements were performed on liquid-phasesintered alumina textured by a templated grain growth process from 1250°to 1650°C. Texture distributions were measured using X-ray pole figures, rocking curves, Rietveld refinement, and stereology. The March-Dollase equation fitted the measured distributions very well and gave quantitative values of the degree of texture and the texture fraction. The fitting parameters of the X-ray diffraction measurements were comparable to those measured by stereology. Rocking curve analysis was found to be straightforward and to give accurate characterization of texture in the alumina system of this study in a relatively short time.

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Section: Discussionmentioning

confidence: 97%

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al₂O₃

Seabaugh

Vaudin

Cline

et al. 2000

Journal of the American Ceramic Society

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“…However, the image analysis anisotropy measurements are a snapshot of powder alignment after powders have settled and solvent (water) elimination. In situ studies during fluid shear determined by X‐ray or neutron diffraction can confirm the alignment of particles in a shear field 33,34 ; however, these are difficult experiments to perform. There is some correlation between the plateau for constant viscosity with increasing shear rates and the plateau for constant K values, and therefore, alignment.…”

Section: Discussionmentioning

confidence: 99%

Factors Influencing Anisotropic Sintering Shrinkage in Tape‐Cast Alumina: Effect of Processing Variables

Patwardhan

Cannon

2006

Journal of the American Ceramic Society

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The effect of the processing variables shear rate, solids loading, and sintering temperature on the anisotropy of sintering shrinkage of aqueous tape-cast alumina was studied. Higher shear rates and higher solids loading resulted in higher in-plane shrinkage anisotropy, whereas the shrinkage anisotropy in the thickness direction was higher for low solids loadings. The in-plane shrinkage anisotropy was found to be fairly constant above a certain critical shear rate (B100 s À1 ) independent of the solids loading. The shrinkage anisotropy through the thickness was higher than in-plane directions. A higher thickness direction sintering rate was observed and attributed to a greater number of interparticle necks in the thickness direction because of the platy nature of alumina particles and the greater thickness direction strains associated with binder removal. The binder did not significantly affect the in-plane sintering shrinkage but significantly affected the shrinkage in the thickness direction. It was suggested that emulsion binder particles occupy sites in between layers of particles in the thickness direction. The degree of anisotropic shrinkage was quantified using edge orientation polarograms and a direct correlation was obtained between the processing variables, shrinkage anisotropy, and the edge orientation index.

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“…To overcome this problem, the solution is to calculate the orientation distribution (OD) of the crystallites from several ( hkl ) distributions, i.e ., to acquire as many pole figures as possible for the nonparallel ( hkl ) crystallographic planes. Bocker et al proposed a procedure to calculate, from the X-ray analysis, the orientation distribution function (ODF) and the related (00 l ) distribution from numerous pole figures. The reliability of the results was proven by comparing the maximum pole densities of various lattices planes measured by X-ray and neutron diffraction.…”

Section: Introductionmentioning

confidence: 99%

Rietveld Texture Analysis of Alumina Ceramics by Neutron Diffraction

et al. 2004

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The orientation distributions of R-Al 2 O 3 textured ceramics are determined from neutron diffraction spectra. A curved position-sensitive detector coupled to a tilt angle (χ) scan allowed the whole diffraction pattern treatment in the combined Rietveld-WIMV-Popa algorithm. Four textured alumina ceramics were prepared by slip-casting under a high magnetic field and sintered at 800, 1300, 1400, and 1600 °C. The calculation of the distribution density, correlated to the representation of the normal and inverse pole figures, highlights the influence of the magnetic field and sintering temperature on the texture development. The principal pole figures show a pronounced (00l) texture: (001) pole parallel to the direction of slip-casting, and (110) pole with higher distribution density for the directions perpendicular to the expected fiber axis. The inverse pole figures calculated for the fiber direction show a major (001) component for all the samples. With the increasing sintering temperature, the texture strength is enhanced and the c-axis distribution is sharper. The effectiveness of the approach for determining the crystallite size is also evident. As a global trend, the calculated crystallite size and observed grain size are similar and increase with the increasing sintering temperature. The mechanism of the texture development in the sintered specimens is certainly initiated from the preferred orientation of the green body after slip-casting under a high magnetic field. The basal texture is enhanced during sintering by selective anisotropic grain growth. We evidenced here the powerfulness of the Rietveld texture analysis to provide a basis for the correlation of texture, microstructural parameters, and anisotropic properties.

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Determination of preferred orientation textures in Al2O3 ceramics

Cited by 16 publications

References 4 publications

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al₂O₃

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al₂O₃

Factors Influencing Anisotropic Sintering Shrinkage in Tape‐Cast Alumina: Effect of Processing Variables

Rietveld Texture Analysis of Alumina Ceramics by Neutron Diffraction

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Determination of preferred orientation textures in Al2O3 ceramics

Cited by 16 publications

References 4 publications

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al2O3

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al2O3

Factors Influencing Anisotropic Sintering Shrinkage in Tape‐Cast Alumina: Effect of Processing Variables

Rietveld Texture Analysis of Alumina Ceramics by Neutron Diffraction

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Comparison of Texture Analysis Techniques for Highly Oriented α‐Al₂O₃

Comparison of Texture Analysis Techniques for Highly Oriented α‐Al₂O₃