C. Bossel et al., PROCESSING OF NANO-SCALED SILICON POWDERS TO PREPARE SLIP CAST STRUCTURAL CERAMICS, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 204(1-2), 1995, pp. 107-112
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.