Rheological Behavior of SiC Aqueous Suspension and Its Effect on the Green Body of Slip Casting

Recrystallized SiC aqueous suspension was prepared by adjusting pH value with HCl and NaOH and using tetramethyl ammonium hydroxide (TMAH) as dispersant. In this aqueous suspension, the particle size of SiC are 100, 5 and 0.6 mu m, and the ratio is 7:1:2. The effects of dispersant concentration, pH value and solid content on the rheological behavior of SiC aqueous suspension were studied. The stable SiC aqueous suspension with high solid content and low viscosity was selected as the target. The results show that the suspension with 0.2 wt% TMAH as dispersant addition and the pH value of 9 has the lowest viscosity at the same solid content. With the increase of solid content, the viscosity becomes higher and higher. When the SiC aqueous suspension with solid content of 67.5% is used for slip casting, the green body has the highest density around 2.39g/cm(3) or the relative density is about 75.9%. The green body has low porosity and the quality is excellent.