Effect of acid leaching on rheological behavior of silicon nitride aqueous suspension

The effect of acid leaching on the rheological behavior and Zeta potential of Si3N4 aqueous suspension was studied. The isoelectric point (IEP) of Si3N4 particles shifts to basic region due to the decrease of the oxidizing degree on the surface of acid leached Si3N4 powder. Because the Zeta potential of Si3N4 particles increases efficiently, the rheological properties of Si3N$-$/4 leached suspensions are significantly improved and the maximum solids loading increases from 50 to 55 vol%. The acid leaching process can be successfully used to optimize the rheological behavior of Si3N4 suspension and to prepare suspension with promising properties.