Effect of Dispersants on the Rheological Behavior of Zirconia‐Wax Suspensions

Three types of fatty acids‐namely, stearic acid, oleic acid, and 12‐hydroxystearic acid‐were used as dispersants for stabilization of highly concentrated zirconia‐wax suspensions. Rheological properties such as viscosity and yield stress of the suspensions were determined over a temperature range of 65°‐85°C. Experimental results indicated that better suspension stabilization was achieved when the 12‐hydroxystearic acid was used. Adsorption behavior revealed a greater affinity at the solid/liquid interface that occurred for the 12‐hydroxystearic acid than for stearic acid or oleic acid. This observation suggests that the adsorption of 12‐hydroxystearic acid may lead to a better packing (or surface concentration) of the acid molecules onto the solid surface than others and also results in a better suspension fluidity and processability. Attractive interparticle interaction was estimated quantitatively by using the Vold model and resulting analysis showed a linear correlation between the yield stress and the attractive potential for the suspensions.