Texture and Properties of α − Al2O3 Substrates

Böcker, A.; Bunge, H. J.; Huber, J.; Krahn, W.; Ruska, J.

doi:10.1155/tsm.24.167

Cited by 9 publications

(20 citation statements)

References 4 publications

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“…Finally the small particle size of the precursor powder (∅=150 nm) is also an important factor to provide the driving force for grain growth. Bocker et al [6] clearly showed that small particles are necessary to develop a strong texture. Here, the specimen sintered at 1600°C exhibits a texture strength almost 8 times higher than the sample sintered at 800°C.…”

Section: Ebsd Data Analysismentioning

confidence: 99%

Texture of Alumina by Neutron Diffraction and SEM-EBSD

Guilmeau

Henrist

Suzuki

et al. 2005

MSF

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Abstract.The orientation distributions of α-Al 2 O 3 textured ceramics are determined from neutron diffraction and SEM-EBSD. A curved position-sensitive detector coupled to a tilt angle (χ) scan allowed the whole neutron diffraction pattern treatment in the combined Rietveld-WIMV-Popa algorithm. Analyses from neutron and electron diffraction data gave similar results if EBSD data are smoothed to account for grain statistics. Four textured alumina ceramics were prepared by slipcasting under a high magnetic field and sintered at 800°C, 1300°C, 1400°C and 1600°C. The inverse pole figures and EBSD-mapping highlights the influence of the magnetic field and sintering temperature on the texture development. 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 combined 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 correlated to SEM-EBSD calculation to provide a basis for the correlation of texture, microstructural parameters and anisotropic properties.

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Section: Ebsd Data Analysismentioning

confidence: 99%

Texture of Alumina by Neutron Diffraction and SEM-EBSD

Guilmeau

Henrist

Suzuki

et al. 2005

MSF

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“…D URING sintering of tape cast products, which require high dimensional accuracy for the use of high-integrated components, an anisotropic shrinkage can be observed, [1][2][3][4] which is attributed to an anisotropic green microstructure. During tape casting, nonspherical particles are oriented caused by shearing and constrained drying [5][6][7] resulting in a higher sintering shrinkage in the thickness direction than in the lateral direction. However, samples composed of spherical particles also exhibit anisotropic shrinkage behavior during sintering.…”

Section: Introductionmentioning

confidence: 99%

Correlation Between Anisotropic Green Microstructure of Spherical‐Shaped Alumina Particles and Their Shrinkage Behavior

Polfer

Kraft

et al. 2015

J. Am. Ceram. Soc.

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Dimensional control is one of the basic problems in ceramic processing, especially for tape cast ceramic sheets which are used to build up multilayer structures for high-integrated components. Uncontrolled anisotropic shrinkage can cause geometrical distortion and circuit failure of multilayer ceramics during sintering. The understanding of the relationship between green tape microstructure and shrinkage anisotropy is of great importance for further miniaturization of multilayer devices. In this study, alumina powders with spherical particle shape were used to cast green tapes. The microstructure as well as the pore orientation and the shrinkage behavior were analyzed. According to the sintering theory, grain growth and pore elimination are the two most important mechanisms to describe sintering shrinkage. In this work, three-dimensional shrinkage behavior of tape cast alumina powders with spherical particle shape was investigated and correlated with pore orientation in the microstructure. Specifically, the reason for the different shrinkage in z-direction compared to the lateral shrinkage is in focus. The study is based on experiments as well as on mathematical visualization.

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“…[36][37][38] Research subject was the texture development in different a-alumina (R 3c) substrate ceramics (circuit carrier ceramics) produced from the manufacturer CeramTech. 38 In the present work one set of these samples with different annealing times was analyzed with our novel FXD-CSD method. In the forming process different binder substances had been tested.…”

Section: Methodsmentioning

confidence: 99%

“…B€ ocker examined the influence of different manufacturing steps prior to sintering on texture development: batching, milling, and forming. B€ ocker et al [36][37][38] report a rather strong texture development. In a subsequent step the influence of the sintering time had been investigated.…”

Section: Methodsmentioning

confidence: 99%

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Determination of crystal size distributions in alumina ceramics by a novel X‐ray diffraction procedure

2017

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A novel X‐ray diffraction based method is presented, capable of determining volume‐based crystal size distribution (CSD) of polycrystalline materials and crystalline powders with unprecedented sampling statistics; the method is named fast X‐ray diffraction crystal size distribution analysis (FXD‐CSD). FXD‐CSD can be performed with standard laboratory X‐ray diffractometers equipped with a position sensitive detector and uses a software package written in Python for the data analysis. FXD‐CSD is a destruction‐free and generally applicable method to establish CSDs of polycrystalline materials as well as powders for sizes well below 1 μm up to about 100 μm; it even allows for studies of samples enclosed in complex environments, e.g., for in situ measurements in a furnace or in a pressure cell. To show the capability of the method the microstructural evolution of four alumina substrates with different time‐spans of sintering (4, 8, 16, and 24 hour at 1600°C) is investigated via FXD‐CSD and SEM imaging. The corresponding CSDs and average grain sizes are determined, results obtained by FXD‐CSD and the line‐intersection methods are compared and clear evidence for the presence of abnormal grain growth (AGG) during sintering is shown. From three tested probability density functions (PDF) describing the CSDs a log‐normal PDF fits best to the volume based CSDs; the method provides size distributions with unprecedented precision opening the way to a systematic and meaningful comparison between theoretically predicted and observed CSDs.

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Texture and Properties of α − Al₂O₃ Substrates

Cited by 9 publications

References 4 publications

Texture of Alumina by Neutron Diffraction and SEM-EBSD

Texture of Alumina by Neutron Diffraction and SEM-EBSD

Correlation Between Anisotropic Green Microstructure of Spherical‐Shaped Alumina Particles and Their Shrinkage Behavior

Determination of crystal size distributions in alumina ceramics by a novel X‐ray diffraction procedure

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