ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 51, (3) 147 - 152 (2007)

Sarraf Hamid, Havrda Jiří
Department of Glass and Ceramics, Institute of Chemical Technology Prague Technická 5, 166 28, Prague, Czech Republic

Keywords: α-Al₂O₃, Electrosteric polyelectrolyte (Dolapix CE64), Shear-thinning behavior, Yield stress, Flow models

The aim of the present work was to investigate the rheological behavior of highly (43 vol%) concentrated sub-micron α-Al₂O₃ aqueous suspensions containing different amounts of electrosteric polyelectrolyte (Dolapix CE64) as dispersant. It was found that in an aqueous alumina/dispersant system, as the amount of dispersant increased up to its optimum, the viscosity and yield stress of the suspension decreased. The flow curves of alumina suspensions illustrated typical shear-thinning behavior and were fitted satisfactorily to the power law, Herschel-Bulkley and Bingham models. The application of various flow models on the alumina systems confirmed that the optimum dispersant concentration which will impart the minimum viscosity to prepare stable suspensions is 0.4 wt.% of Dolapix CE64. Finally, the results obtained from rheological measurements indicated that dispersant Dolapix CE64 has great efficiency in electrosterically dispersing of concentrated alumina suspension and enables the preparation of lower viscous suspensions, suitable for colloidal processing such as slip-casting

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