Effect of preparation methods on rheological properties of Al2O3/ZrO2 suspensions

The dispersion and stability of aqueous Al2O3/ZrO2 suspensions containing polyelectrolyte under acidic conditions was investigated in this study. It was found that binary suspensions with identical polymer concentration, solids loading and solution conditions, but prepared by different methods, differed significantly in their rheological behavior. When binary suspensions were prepared by adding mixed Al2O3 and ZrO2 powder to aqueous solution directly and ammonium polyacrylate (PANH(4)) content was an average of that of dispersed Al2O3 and ZrO2 unary suspensions, the desired stability level cannot be obtained in this system. When binary suspensions were prepared by mixing two types of dispersed unary suspensions, it was found that the mixture exhibited a high viscosity and shear thinning behavior with the mixing duration increasing. Whereas when alternating processing route during the binary suspensions preparation, viz., first adjusting pH value of solution to alkaline range before getting final acidic environment, the optimum rheological behavior can be realized in these, samples. The distribution state of polymer on particle surface and competitive effects stemming from different affinity of Al2O3 and ZrO2 for polymer were discussed and related to the system stability. (c) 2006 Elsevier B.V. All rights reserved.