Shear Modulus and Yield Stress Measurements of Attractive Alumina Particle Networks in Aqueous Slurries

The shear modulus and yield stress of attractive alumina particle networks in aqueous slurries was determined as a function of volume fraction (0.1 to 0.5), pH (2, 4, 5, 6, and 9), and salt (NH₄l) concentration (0.25M to 2.34) using both vane and couette rheological tools. Consistent with previous observations concerning the relative strength of attractive particle networks, the shear modulus increased to a plateau value with salt concentration. In this work we have shown that the salt concentration at which this plateau value is achieved is a function of the pH, and thus, the surface charge density. The values of the shear modulus G'], yield stress τ_y], and yield strain γ_y] of the attractive networks can be described with power law functions for particle volume fraction φ] (G'∝φ^4.75, τ_y∝φ^3.6, and γ_y∝φ^?1.1) and salt concentration c] (G'∝ c]^2.0, τ, ∝ c]^1.15, and γ_y∝ c]^?0.85).