Effect of processing route on the stability of aqueous ZrO2 suspensions

The relationship between processing route and suspension stability in ZrO2-H2O-PANH(4) system was investigated through rheology study. The work showed that two suspensions with identical PANH(4) concentration and final solution condition but prepared by different routes differed greatly in stability. This behavior is attributed to their different distribution state of PANH(4) on ZrO2 surface that is determined by the adsorption affinity depending on pH condition in solution. High affinity at pH 5.0 induces a nonuniform distribution of soluble PAA(-) (polyacrylicacid) on particle surface, which can flocculate the suspension strongly, while low affinity at pH 9.0 induces an uniform distribution of polymer so that the higher stabilization can be achieved. A simple mathematical model was used to account for the observed results.