Rheological analysis of stabilized cerium-gadolinium oxide (CGO) dispersions

The objective of the present work is to generate general rheological criteria to investigate high solid loading dispersions suitable for the shaping of homogeneous ceramic bodies. Systematic analysis of the rheological properties of moderately low specific surface area (SSA) Ce0.9Gd0.1O3-δ (CGO10) dispersions was performed in rotational and oscillatory modes. The dispersant content was optimized to attain fully stabilized dispersions. A critical upper limit for the ceramic content was introduced and denoted ϕh. It defines the limit to non-Newtonian flow and corresponds to the highest feasible volume fraction to which reproducible dispersions are achieved. The method proposed for its determination is based on the analysis of the flow index as function of the ceramic volume fraction. For the CGO dispersions formulated in this work, ϕh was found to be around (0.34 ± 0.04). The maximum volume fraction (ϕm) was also estimated and found to be (0.55 ± 0.01).