Based On The Rheology Research The Structure Of Formation And Change Of Fume Silica Suspensions

Now the structure of suspensions are mainly studied from the point of view of theparticles dispersion, but the suspensions of large particles are affected significantly by gravity,which make the suspensions become the blind spots of structure studying. Rheology is mainlystudied the flow and deformation of suspensions, which inevitably involves the change ofsuspension’s structure, and then the structure is characterized directly. The fume silica(d50=0.216um) suspensions are as the research object. The process of formation, destroy andrecovery of suspensions are systematically studied form the relationship betweenrheological properties and structure.From the reason of formation of fumed silica suspensions and corresponding rheologicalproperties, the relationship between Suspension structure and rheological properties arestudied. The results show that the Si-OH bond of surface of silica particles impact therheological behavior. Solid content, additive and temperature can affect Si-OH bond, whichchanged the acting force between particles, thereby changing the rheological properties.The shear thinning behavior of fume silica suspensions are studied, which is conformitywith the process of particles reunification. The process of agglomeration meet Southerlandghost model according to the observation of transmission electron microscope, and thestructure of agglomerated particles are loosen. It is the loosen structure of agglomeratedparticles that affect the shear thinning behavior of fume silica suspension. The process ofshear thinning behavior of fume silica suspension is the decomposition process ofagglomerated particles, namely, the formation process of the structure.Suspensions of fumed silica exhibit destroy experiments under steady shear and dynamicshear with rheometer by coaxial rotation shear (CRS), small amplitude oscillatory shear(SAOS) and big amplitude oscillatory shear (BAOS), in order to characterize the rheologicalbehavior of suspensions after shearing, then obtaining the dynamics of the structure and thestructure damage condition of suspensions. Cox-Merz empirical formula is suitable forsuspensions of fumed silica. The structure parameters are ascertained at the beginning of structure destruction and flow.From the view of point of thixotropy, the recovery process of structure is studied. Erroranalysis and optimization are used in the thixotropy measurement. Rotation-oscillations-rotation applied to the thixotropy measurement was the optimized method. It notonly had granular particles themselves, but also had the property of polymer chain. Theparticles aggregation and particle chains were the cause of the suspension thixotropy.