DEEP ELECTROPHORETIC PENETRATION AND DEPOSITION OF CERAMIC PARTICLES INSIDE POROUS SUBSTRATES .2. EXPERIMENTAL-MODEL

The objective of the present study was to experimentally evaluate the feasibility of depositing ceramic particles on the surface of a porous substrate and inducing them into it by electrophoresis. It was demonstrated that it is possible to charge and electrophoretically deposit both oxide (fused and colloidal SiO2) and nonoxide (SiC and SiN) ceramics on a conductive graphite substrate. It was also shown that ceramic particles are induced into porous graphite, and that under optimal conditions the whole cross section of the specimens was penetrated. The amount of induced material was found to increase with the ratio of dielectric constant to viscosity (epsilon-n) of the solvent, as well as with particle concentration and field intensity. However, due to simultaneous buildup of an overlying deposit, penetration as a function of deposition time reaches a plateau prior to the filling of the whole pore volume.