The role of Si–O species in the colloidal stability of silicon-containing ceramic powders

The relative colloidal stability in ethanol of ceramic powders with Si–O surface groups (Si3N4, SiC and MoSi2) is reported. SiO2/EtOH suspensions are also examined as reference. The comparative relationships between pH, particle-surface charge, zeta-potential, stability and suspension rheology are discussed. The nature and influence of the surface species is determined and the similarity/difference therebetween, compared. DLVO theory and Stability Ratio values defined suspension stability and it was found non-oxide particles in EtOH are charged-stabilized and have viscosity and flow-curves that agree with the electrokinetic measurements.