A study of the rheological behaviour of alumina and of silicon carbide in aqueous suspensions was carried out with the purpose of evaluating processing conditions that enable simultaneous dispersion of both raw materials. The dispersing agents used in this work were polyelectrolytes, including a salt of polymethacrylic acid and polyethyleneimine. The isoelectric points (iep) of powders were determined in aqueous suspensions either in the presence or not of deflocculants. The deflocculant concentration that promotes best dispersion, as well as the influence of pH and of solids content on the stabilisation were evaluated through viscosity and zeta potential measurements. It was verified that alumina and silicon carbide can be simultaneously dispersed at pHs where high surface charge of same sign is obtained for both powders, preferably using the same type of dispersant.
