A new method for judging and predicting the stability of ceramic suspensions by rheological tests

In preparing stable ceramic suspensions, the interactions of particles and polymer chains should be emphatically considered, which depends on DLVO stabilization theory. However, DLVO stabilization theory are qualitative and lack quantitative methods for judging and predicting stability. The present study introduced a new method for directly judging and predicting suspension stability based on rheological tests and established a correlation between measured data and the state of ceramic suspensions. Among rheological properties, the dominance of the storage modulus G' is more conducive to the realization of steric stabilization, whereas the loss modulus G" exerts a more significant influence in bridging and depletion flocculation states. The stability of suspensions with a given particle size can be judged and predicted by comparing the value of tan δ (the ratio of G" and G') under identical measurement conditions. Lower values of tan δ indicate better stability of the ceramic suspensions. The new method has been verified by experiments of classical alumina suspensions. The results indicate that the alumina suspensions with 14, 17, 20, and 23 vol.% of solid particles exhibit optimal stability when combined with PVA concentrations of 3.5, 3.0, 2.5, and 2.0 wt.%. Meanwhile, this combination leads to the minimum values of tan δ within the linear viscoelastic region (0.71, 0.45, 0.33, and 0.31, respectively). The universality of the method has been further demonstrated in zirconia suspensions dispersed with Dolapix CE64 dispersant. The application of this method has demonstrated its significance in judging and predicting the stability of ceramic suspensions.