Theoretical determination of floc size in highly-concentrated zirconia–wax suspensions

Abstract

In this investigation we propose a model capable of calculating the size of flocs in flocculated suspensions. The model is based on two major parameters, namely shear stress ( τ)-dependent viscosity, η r( τ), and shear stress τ-dependent maximum packing fraction, φ m( τ), of the suspensions. Model suspensions of highly-concentrated zirconia-wax mixtures, exhibiting a pseudo-plastic behavior, were prepared to elucidate the feasibility of the model. The resulting calculations show that the floc size, relative to the particle size, decreases exponentially with increasing shear stress. This is analogous to the shear stress – shear viscosity relationship commonly observed in flocculated suspensions. A linear relationship between the floc size and suspension viscosity was found. A direct and quantitative correlation between rheological properties and the corresponding structural evolution of the suspensions is proposed.