Effect of processing route on rheological properties of Al₂O₃-SiO₂/PAA suspensions

The dispersion and stability of aqueous Al₂O₃/SiO₂ binary colloidal system were investigated at different pH values. Based on the above experiment, the rheological properties of the binary suspensions of Al₂O₃-SiO₂ containing PAA was tested by decentralized route. The experimental results show that in the absence of dispersant, the rheological properties of Al₂O₃-SiO₂ binary suspensions as a function of pH was divided into three sections. At pH<2.0 and pH>9.0, the binary suspension was well-dispersed. At pH=2.0-9.0, the binary suspension was strongly flocculated, and had higher degree of flocculation than the unary suspension. However, it was well-dispersed by adding PAA at pH 2.0-9.0. The minimum amount of PAA was 0.8wt% by using the common adding ways at pH=6.0. After changing the processing route, the minimum amount could be reduced by 50%, only 0.4wt%. The results show that a heterogeneous distribution of PAA on particle surface in the Al₂O₃-SiO₂ slurries, and the pheonmenon could be avoided by optimization of processing route. In addition, with the optimization of processing route containing PAA in Al₂O₃-SiO₂ binary suspensions, the system obtained superior anti-electrolyte performance. At the same time, effect of soild loading on rheological properties of slurries was moderated.