Centrifugal Processing of Ceramic Materials

Researchers have demonstrated that unique properties can be developed in materials using powder slurry green bodies that are formed using centrifugal processing. Highly anisotropic layered, gradient or oriented materials can be readily produced using the added gravitational acceleration of centrifugal processing to control particle arrangement and produce useful shapes. For layered or gradient materials the microstructural characteristics are so tied to processing that the part geometry can have tremendous impact. This approach has been successfully applied to fabricate high temperature superconductor tubes for magnetic shielding. In this processing technique, the orientation of the plate-like Bi-superconductor grains is used to obtain desired preferred orientations in green state processing.

A related research program on ceramic composites has explored routes to introducing gradient and layered ceramics and ceramic composites for structural and electronic applications. In centrifugal processing of composite slurries, segregation of different size and different density slurry additions is governed by the colloidal state of dispersion, solid loading and effective settling distances. Although a number of investigations have described the factors controlling segregation, the complex interactions between particles as a function of solid loading remains poorly described. MSE research on platelet-reinforced composite slurries, it is apparent that the local interactions between particles may have strong effects on segregation in even very dilute slurries.