Influence of Sodium Silicate Modulus on Rheology of Kaolin Slurry

Abstract

Abstract: In this study, sodium silicate with varying modulus was synthesized. The influence of sodium silicate modulus on the rheology of kaolin slurry was investigated. Based on the rheological analysis, it has been determined that the kaolin slurry exhibits the lowest shear viscosity when the sodium silicate modulus is 2.5 and the addition amount is 0.33% (mass fraction). Four different models are used to fit the flow curves, and it is found that the Herschel-Bulkley model could obtain the greatest correlation. In addition, the fitting degree is primarily influenced by the shear stress in the low shear rate region, which is mainly affected by the thixotropy of slurry. Then, the thixotropy of slurry with different sodium silicate modulus is characterized by shear hysteresis ring area, which verifies the view above. Finally, the molecular structure of sodium silicate with different modulus was analyzed using infrared spectroscopy. The results indicate the presence of a weak vibration at 589.5 cm^-1 in the vibrational spectrum of sodium silicate with a modulus of 2.5, suggesting the presence of distorted 6-membered rings. The annular silicates interact with kaolin particles through Coulombic force, leading to the formation of large aggregates. This interaction prevents the connection between the edges and faces, disrupts the thixotropic structure, and consequently reduces viscosity. This study is helpful to understand the deep reason of the influence of sodium silicate modulus on the mechanism of deflocculation, and provide scientific basis for optimizing the formulation and processing of ceramic slurry.

Key words: sodium silicate, modulus, kaolin, slurry, rheology, thixotropy

CLC Number:

TQ174

LI Gang, BAO Zhilei, ZHANG Junjian, YU Huan. Influence of Sodium Silicate Modulus on Rheology of Kaolin Slurry[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(12): 4475-4481.

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