pH Controlled Dispersion of Non-oxide Ceramic Powders in Aqueous Media

The dispersion of Si, SiC and Si3N4 powders in deionised water was optimized as a function of pH in the range 2-12. Various experimental techniques like particle size analysis, sedimentation, viscosity and rheology and electrokinetic behaviour were used to characterize the slurries. The optimally dispersed slurry displayed minimum sedimentation height, minimum viscosity, near newtonian flow behaviour and maximum zeta potential. When cast into plaster moulds, the 44 vol% SiC and Si3N4 slips and 52 vol% Si slips yield green bodies having 55-65% of theoretical density.