PROCESSING OF NANO-SCALED SILICON POWDERS TO PREPARE SLIP CAST STRUCTURAL CERAMICS

For slip casting of ceramic powders it is necessary to have a well-def ined and thus disagglomerated colloidal suspension. Proper selection o f the solvent is required in order to achieve separation of the partic les to obtain a homogenous mixture of the powders which is necessary f or shaping complex geometrical structures, often used in structural ce ramics. Here we report a preliminary investigation of the deagglomerat ion phenomena of nano-scaled silicon powders obtained by plasma induce d dissociation of silane and compare it with silicon nitride powders p repared by laser induced condensation reactions and a commercial produ ct (UBE SE E-10). The size dispersion of aggregates in colloidal suspe nsions, determined by photon correlation spectroscopy and sedimentatio n particle size analysis techniques, varies from 20 to 500 nm. Variati on in the deagglomeration properties of the particles in different sol vents depends on the surface property of the powders, and on the inter -particle interactions. These are studied with respect to the variatio ns in the surface property of the powders in different solvents. Ethan ol was found to be a suitable solvent for the colloidal suspension as the average aggregate radii of the silicon powders could be reduced to 80 nm.