Slip casting of SiC-SiAlON composites

SiC-SiAlON composites were prepared by the reaction sintering of SiC, kaolin and silicon mixtures in a nitrogen atmosphere. To form complex shapes, slip casting was used, with water preferred as an economic dispersion medium. The methodology to obtain a highly concentrated, well-dispersed, slurry (73% by weight of dry matter) is described. Zeta potential and complementary redox potential measurements revealed the nature of the surface species as a function of pH and indicated compatible conditions for the three constituents (kaolin, SiC, Si). Sodium metasilicate was used as deflocculant and CMC as organic binder.