Colloidal stabilization of cerium-gadolinium oxide (CGO) suspensions via rheology

A rheological method based on the analysis of the flow index is proposed for the optimization of ceramic suspensions with respect to dispersant-ceramic affinity, dispersant concentration, and ceramic loading. The single-flow index (SFI) feature was identified as the criterion defining the optimized colloidally stable state. The method was applied to explore the ability of four commercial dispersants (acidic affine, neutral, basic affine, and polyvinylpyrrolidone (PVP)) to disperse cerium-gadolinium oxide (CGO) in ethanol. Only the acidic affine and the PVP dispersants were found to efficiently disperse the CGO powder. The acidic affine dispersant was further demonstrated to impart superior packing properties due to the formation of a thinner monolayer around the ceramic surface. CGO suspensions using the acidic affine at optimized amount were prepared and processed via tape casting. The resulting green tapes exhibited uniform and high packing density, producing a theoretical density in the sintered tapes of ca. 97–98%.