Abstract & Overview
Slip casting is a widely used colloidal technique for consolidation of ceramic powders from a suspension.The colloidal approach ensures homogeneous microstructure of a green body, thereby reducing post-sintering machining and production costs.The process consists of several steps.The first step is to mix the ceramic powder with a liquid, usually water, where the stabilization of the new obtained suspension with different dispersants follows.When an optimum dispersion of particles is achieved, resulting in low slip viscosity, ceramic slurry can finally be poured into a porous mould, usually a gypsum one.The influence of different dispersants on rheological properties of highly concentrated alumina (Al 2 O 3 ) suspensions was investigated.The used dispersants were: ammonium polymethacrylate water solution (Darvan C-N), 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt (Tiron) and citric acid.The amount of dispersants was varied from 0.1-1.25 wt.% in order to determine the optimum.Rheological properties of the prepared suspensions were determined by measuring the apparent viscosity at different shear rates.The obtained optimal amount was 0.75 wt.% for Darvan, 0.1 wt.% for Tiron and 0.3 wt.% for citric acid.The obtained results show that the most effective dispersant is 4,5-dihydroxy-1,3benzenedisulfonic acid disodium salt, given that only 0.1 wt.% was required to stabilize the 70 wt.% Al 2 O 3 suspension.