KEY FACTORS AFFECTING THE RHEOLOGICAL BEHAVIOR OF Al_2O_3 AQUEOUS SLURRY

The rheological properties of Al2O3 aqueous slurry, pH in more than 7 were examined by means of the rheological method with RV-20 rheometer. The effects of the solid loading, contents of dispersant, sintering additives and plasticizer on the rheological properties were investigated. It was found that Al2O3 alkaline slurry shows shear thinning behavior at lower shear rates (100 s-1). After the addition of MgO, hydrolyzation occurred in the aqueous slurry, which could cause the slurry to lose fluidity. The viscosity of the slurry was changed slightly when glycerol was used as a plastic additive, which would not affect the solid loading and casting procedure. When aqueous acrylic acid latex was added, the Al2O3 slurry also showed a shear thinning behavior at lower shear rates (100 s-1). Furthermore, the static viscosity of Al2O3 slurry shows an increase with the increase of the content of aqueous latex. The dispersant content has a remarkable effect on the stability of the Al2O3 slurry. When the dispersant polyacrylic acid-NH3 content is 0.8% of the mass fraction of the solid phase, the adsorbed state of ceramic powder surface is saturated, so the suspension of Al2O3 slurry reaches maximum stability.