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Abstract

Preparation and colloidal dispersion of highly concentrated biocompatible nanoparticles suspensions are vital for fabrication of dense bioceramic nanocomposites with improved mechanical and microstructural properties for biomedicine applications. This paper presents formation and rheological characterization of highly concentrated biocompatible aqueous ZrO2 nanosuspensions for such applications. The rheological properties including viscosity (η), shear rate (γ), and shear stress (τ) were investigated in relation to a wide range of solid loading (ϕ, by weight = 75-78 mass%). Maximum solid loading (ϕmax) was estimated with a constant 0.9 mass% concentration of a new type of anionic polyelectrolyte Dolapix CE64, suitable for casting of materials. A colloidal model was proposed to visualize the effect of solid loading on colloidal stability, rheological behavior and green microstructure of samples after casting. The maximum solid loading (ϕmax) was estimated to be 77 mass% based on the dependence of both viscosity (η) and yield stress (τ0) on solid loading (ϕ). For further validation, the maximum solid loading was compared and fittedby different rheological flow models with a correlation factor r = 0.998 for Herschel-Bulkley model, r = 0.999 forPower law model and r = 0.920 for Bingham model at shear rate γ (50 s-1). All concentrated ZrO2 nanosuspensions exhibited shear-thinning behaviour. The results obtained from rheological measurements, scanning electron microscopy imaging and flow models validate our proposed hypothesis for prediction of maximum solid loading and visualization of quality of green microstructures after casting. These results contribute to preparation, characterization, and processing of highly concentrated bio/nanoparticles suspensions; aiming to fabricate highly dense bio/nanocomposite materials with specific functionality.