The maximum solid loading and viscosity estimation of ultra-fine BaTiO3 aqueous suspensions

The rheological behavior of ∼100 nm barium titanate (BaTiO3) powder aqueous suspension has been investigated over a wide range of volumetric solids loading (ϕ = 0.1–0.53), in which ammonium polyacrylate (NH4PA) was used as a dispersant. The dependence of relative viscosity (ηr)–solids loading (ϕ) determined experimentally was compared with various existing models. The experimental results showed that the suspension apparent viscosity (η) decreased pronouncedly as the dispersant addition was increased, and the η reached a minimum as the dispersant addition exceeded 0.7wt.% (based on the dry powder weight), the viscosity increases with the solids loading and also show that the rheological behavior of the suspension was content basically with the model proposed by Liu and Mooney, and was discrepant to others. From ηr–ϕ relationship the maximum solid loading (ϕm) was estimated to be 0.544. The fact is that yield stress (τy) of the suspension presented power-law dependence with ϕ further substantiated the validity of ϕm calculated. The model proposed by Liu and Mooney appears reasonably predicting the relative viscosity over a concentration range of ϕ = 0.3–0.5. In fact, our experimental results showed that ϕ might reach 0.53.