Gelcasting of concentrated aqueous silicon carbide suspension

Gelcasting of high concentrated aqueous silicon carbide suspension with 50 vol.% solids loading is discussed in this paper. It is found that SiC powder is suitable for being suspended in basic solution, provided that a proper pH value is chosen for it. The rheological property of SiC suspension is also affected by solids loading. When SiC slurry is cast at 70°C, reaction between free Si on the surface of SiC powder and an organic base used as dispersant gives out H2 gas, which produces pores in green bodies. However, by vacuum pumping and controlling pH value of the suspensions, complicated shapes of uniform SiC green bodies without pores are prepared.