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Effect of Forming Techniques on the Orientation of Platelet Composites

Published online by Cambridge University Press:  25 February 2011

Yeong-Shyung Chou
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802
David J. Green
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802
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Abstract

Two forming techniques, i.e., slip casting and dry compaction, have been employed to make SiC(platelet)-A1203 composites. The orientation of SiC platelets in the composites, before and after hot pressing, was studied using optical microscopy and a pole-figure X-ray device. It was found that the preferred orientation in the dry-pressed green bodies increased with increasing pressure, whereas the platelets in the slip cast bodies were close to a random orientation. The pressure during the hot pressing process did, however, align the platelets of slip-cast composites during densification. Optical micrographs confirmed the platelets tend to align with their faces perpendicular to the hot pressing direction. The effect of platelet size on the orientation was also investigated. X-ray analysis showed that small platelets (∼ 1.6 μm) do not give rise to preferred orientation both in green and hot pressed bodies; whereas larger platelets (∼24 μm) with larger aspect ratio do yield a stronger preferred orientation. The causes for the platelet alignment will be discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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References

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