Effect of dispersant concentration on rheological behavior of SiC aqueous suspension

Using tetramethyl ammonium hydroxide (TMAH) as dispersant for SiC aqueous suspension, the effects of dispersant concentration and pH value on the rheological behavior of SiC aqueous suspension were studied. The results show that TMAH can improve dispersion by increasing the negative zeta potential of SiC particles and decrease the viscosity of SiC aqueous suspension. At pH value of 10, the absolute value of zeta potential with adding 0.3% and 0.6% (in mass fraction) dispersant increases to 11.7 mV and 22 mV, respectively. The suspension with 0.6% dispersant addition has the lowest viscosity at different solid loadings. The recommended amount of TMAH is 0.6% in order to obtain the minimum viscosity and the maximum negative zeta potential. Excessive dispersant will increase the ionic concentration in suspension and reduce the thickness of double electrical layer. The optimum dispersion occurs at the value of pH 10. The dispersion mechanism by TMAH is discussed.