Investigation On Dispersion And Stability Of α-Al₂O₃ Aqueous Suspension

The novel colloidal forming developed in recent years enabled the forming of high density, large dimension, defect-free, complex-shaped ceramics with high quality. The high strength of Green body is afforded to being manufactured. Recently, the colloidal forming techniques have drawn a great attention in ceramic field. The preparation of a stable colloidal suspension with high solids loading and low viscosity is the prerequisite for colloidal forming process. Yet, many problems involved in colloids forming process needs to be investigated, such as the dispersion of suspension, the rheological properties of the slurry and the surface modification of powders.The effect of dispersant mass fraction and pH on the suspension of particles and in the α- Al2O3 suspension system and the viscosity of α- Al2O3 suspension system were investigated by ζ potential, sedimentation and viscosity measurements. The aim is to study the effect of dispersant mass fraction and pH on the stability of α- Al2O3 suspension.The results indicated that, for suspension system, the variation tendency of stability with the change of dispersant mass fraction was almost same by using the viscosity and sedimentation measurements. The viscosity experiment showed the optimum dispersant mass fraction was 0.04% and the lowest viscosity of α- Al2O3 suspension was obtained under this condition. The results further displayed the optimum dispersant mass fraction remained as a constant, which is independent on the solids loading. In low solids loading, the low viscosity and stable Al2O3 suspensions were obtained within a wide range of dispersant mass fraction.The micrograph of α- A12O3 suspension actually exhibits the dispersed state of particles. It indicated that particles flocculate as dispersant mass fraction is lower than the optimum dispersant mass faction, and good dispersed states can be observed when dispersant mass fraction is within 0.04%~0.22%, which is agreed with viscosity and sedimentation measurements.Comparing the viscosity of low solid loading of α- Al2O3 suspension via pH with ζ...