Shape forming of ceramic powders by manipulating the interparticle pair potential

New forming technologies have been developed for advanced ceramic powders by manipulating the potential between particles using either the electrostatic or the steric method. The important aspect in either case is the development of a short-range repulsive potential, which is summed with the pervasive attractive van der Waals potential to produce an interparticle pair potential characterized by a well in which particles sit at an equilibrium separation distance. This interparticle potential makes it more difficult to push the particles into contact during consolidation, and it controls the flow behavior of the consolidated body. Flow stresses in the range of 0.1 MPa impart clay-like behavior and opportunities for pressure forming. Much smaller flow stresses allow shape forming via Colloidal IsoPressing, where weakly attractive particles are forced into contact within a rubber mold to produce an elastic body that can be removed from the mold without shape distortion. In these approaches, strength degrading inclusions can be removed prior to consolidation by passing the powder, formulated as a dispersed slurry, through a filter to produce more reliable ceramic components. (C) 2001 Published by Elsevier Science Ltd.