Alumina Layer (alumina + layer)

Distribution by Scientific Domains


Selected Abstracts


Development, Analysis, and Application of a Glass,Alumina-Based Self-Constrained Sintering Low-Temperature Cofired Ceramic

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2007
Takahiro Takada
The effects of an inner constraint layer and alumina particles on the microstructure, strength, and shrinkage of the laminated low-temperature cofired ceramic (LTCC) green sheet were investigated. Alumina particles of several sizes were used in the inner-constraint layer in order to strengthen the LTCC substrate. Smaller alumina particles in the inner-constraint layer produced a substrate with a high bending strength. Sintering shrinkage in the x,y direction of the LTCC is related to the bending strength of the debinded alumina particle layer used for an inner-constraint layer. A larger pore size in the inner-constraint layer was found to increase the distance of the glass penetration from the glass,alumina layer into the inner-constraint layer. The total thickness of the constraint layer changes the shrinkage in the x,y direction and the bending strength. [source]


Crack Interactions in Laminar Ceramics That Exhibit a Threshold Strength

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2004
Haksung Moon
Laminar ceramic composites have been fabricated with thin compressive layers, containing a mixture of alumina and mullite, sandwiched between thicker alumina layers. It has previously been shown that a single crack that extends within a thicker alumina layer can be arrested by the compressive layers to produce a threshold strength, i.e., a strength below which the probability of failure is zero. The behavior of multiple cracks within the laminate has been investigated, to observe the mechanisms of crack interaction and measure their influence on the threshold strength. It was found that when the cracks in adjacent thick layers were offset by a distance less than the thickness of two thick layers, the cracks would interact and decrease the threshold strength. The number of interacting cracks, their orientation, and location can also have an effect on the threshold strength. [source]


Laminar Ceramics Utilizing the Zirconia Tetragonal-to-Monoclinic Phase Transformation to Obtain a Threshold Strength

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2002
Michael G. Pontin
Ceramic laminates have been fabricated with thin layers, containing a mixture of unstabilized zirconia (MZ-ZrO2) and alumina (Al2O3), sandwiched between thicker layers of alumina that contain a small fraction of Y2O3 -stabilized tetragonal ZrO2 to inhibit grain growth. The MZ-ZrO2 undergoes a tetragonal-to-monoclinic phase transformation during cooling to produce biaxial compressive stresses in the thin layers. Cracks that extend within the thicker alumina layers can be arrested by the compressive layers to produce a threshold strength, i.e., a strength below which the probability of failure is zero. Laminates composed of Al2O3 layers 315 15 ,m thick and Al2O3/MZ-ZrO2 layers 29 3 ,m thick exhibit a threshold strength of 507 36 MPa, regardless of the MZ-ZrO2 content, for volume fractions ,0.35. These results, piezospectroscopic stress measurements, and microstructural observations suggest that microcracking produced during the transformation reduces the magnitude of the compressive stresses achieved, which in turn limits the magnitude of the threshold strength. [source]