A SiC power of median size 0.8 mum was mixed with an Al2O3 powder of median size 0.2 mum in a 0.3 M-Y(NO3)(3) solution at pH 5 to distribute homogeneously the sintering additives (Al2O3+Y3+ ions) on the SiC particles. In a 30 vol% SiC suspension, the network structure of SiC particles was formed by heterocoagulation through the adsorbed Al2O3 and Y3+ ions. The size of the agglomerated SiC particles and the apparent viscosity of the SiC suspension were measured in relation to the interaction of the SiC-Al2O3-Y3+ ions system. The aqueous suspension of the SiC-Al2O3 (1.17% against SiC content)-Y3+ ions (0.94% Y2O3 against SiC content) system was consolidated by filtration through a gypsum mold to form green compacts of 52similar to55% of theoretical density. These compacts were pressureless-sintered or hot-pressed at 1850degreessimilar to1950degreesC. The densification of the SiC was enhanced with grain growth in the following order of sintering additives: no additive approximate toY(3+) ions < Al2O3 < Al2O3+Y3+ ions. The hot-pressing under a pressure of 39 MPa gave dense SiC of 95similar to99% of theoretical density. The densification mechanisms and the sintered microstructures were also investigated.