A model for predicting the stability of ceramic suspensions

The prediction of the stability of ceramic suspensions with multiple particles is limited depend on classical DLVO theory or Stokes equation. The mechanical effect of particles settling in suspension was studied, and a simplified mechanical equilibrium model of particles was proposed, shown as follows: u=Δρgd218η−τyd36η. The sedimentation of particles is mainly influenced by the density difference between particles and fluid Δρ, particle size d, suspension viscosity η, as well as shear yield stress τy. For a given suspension, Δρ, d and η are constants, and τy can be directly measured through rheological methods. When calculated settling velocity of particles approaches infinitely small values, the suspensions can be considered stable. The expression derived in this work had been verified by the experimental data. In addition, correlation between the results from improved settlement height method and the calculated settling velocity was established. To further investigate the impact of additives on suspensions stability, the Kelvin-Voigt rheological model was employed to characterize viscoelastic properties during oscillation, and a coefficient K (K=τy−G′γcτy) was proposed to quantitatively determine the contribution of the “dashpot” component in influencing the yield stress τy. The regulation strategy for additives in suspensions was established based on experiments: a K value exceeding 0.274 indicates excessive additives concentration and necessitates reduction, whereas a K value below 0.274 suggests an insufficient additives concentration and requires additional dosage. In summary, the above model is helpful to predict the stability of ceramic suspensions.