Rheological behavior of nanocrystalline / submicron ceramic powder dispersions

Abstract

Several rheometric techniques were applied to submicron and nano ceramic powder dispersions systematically in this study. The rheological behavior of the dispersions was determined by steady shear and dynamic shear rheology. Dynamic shear rheological techniques are scarcely used for the characterization of ceramic powder dispersions contrary to polymers.The flow behaviors of the submicron and nano dispersions were found to be dependent on the solids content and fructose concentration. The submicron alumina, nano alumina, and nano titania dispersions in fructose solution showed shear thinning behavior and were fitted to the Herschel-Bulkley model.The dynamic shear rheology measurements showed that the solid part of the dispersions was dominant over the liquid part for both submicron and nano powder dispersions. The elastic modulus was higher than the viscous modulus in stress and frequency sweep measurements. The elastic moduli of the dispersions with solids content lower than 40 vol% were dependent on the angular frequency which indicated a gel-like behavior. However, the elastic moduli of the dispersions with 40 vol% solids were independent of angular frequency which indicated a solid like behavior. Further increase in fructose content had significant effects on both steady shear and dynamic shear rheological behavior of the dispersions regardless of particle size. The submicron and nano ceramic powder dispersions can be prepared by using fructose for the regulation of the rheological behavior of ceramic powder dispersions. The characterization of powder surfaces is essential for the effective adsorption of fructose.