Viscosity of Electrostatically Stabilized Dispersions of Monodispersed, Bimodal, and Trimodal Silica Particles

Abstract

Effect of particle size and polydispersity on the viscosity and maximum packing fraction of aqueous colloidal dispersions has been studied. For dispersions of mono-sized particles, the results indicate that there is a linear relationship between the log(g) (viscosity) and particle size at a fixed shear rate and volume fraction of solids. However, there is a particle diameter at which there is a decrease in the dependency of viscosity on particle size as the slope of the linear plots of log(g) versus particle diameter changes to a smaller value. Preliminary calculations indicate that this particle size may correspond to a separation distance at which electrostatic energy as compared with the thermal energy of the particles can be ignored. In the case of bimodal dispersions, the viscosity is affected by both absolute size and the ratio of the two sizes. The effect of particle size ratio on the viscosity was investigated using bimodal dispersions of the same size coarse particles, but fines of different sizes. There is a critical volume ratio below which bimodal dispersions of larger size ratios show lower viscosities than systems of smaller size ratios. Above this volume ratio of the two sizes, the trend becomes reversed and the fines will have a dominant effect on the viscosity behavior of the bimodal system. Statistically designed experiments were carried out using trimodal mixtures of monodispersed silica particles and it was shown that tridispersed suspensions demonstrate similar behavior as bidispersed suspensions, with a minimum in viscosity observed as a function of particle volume ratio.

Relationship between Rheological Behaviour and Final Structure ofAl2O3and YSZ Foams Produced by Replica

“…The smaller HA for Al 2 O 3 ceramic suspensions may be attributed to the wider distribution of particle sizes, which provides for a better particle packing and decreases the suspension viscosity. This effect of the viscosity in ceramic suspensions has been reported elsewhere [30].…”

Research on laser-assisted selective metallization of a 3D printed ceramic surface

“…The operation mode was set as positive and negative rotation for 8 h. The 5 mm particle size gives the ceramic slurry good uidity, while the 500 nm particle size can reduce the surface defects of the sample during debinding and sintering and improve the density. 24,25 The photosensitive resin can undergo polymerization, cross-linking and curing reaction between monomers to become solid under 405 nm ultraviolet light. The dispersant can prevent the agglomeration of powders and improve the forming quality.…”

Additive Manufacturing of Monolithic Microwave Dielectric Ceramic Filters via Digital Light Processing

“…Previous theoretical and experimental studies have demonstrated that the combination of powders with different particle sizes is an effective method for increasing the volume fraction and reducing the viscosity of the ceramic slurry. Moreover, the density of the sintered body made of powders of different particle sizes is higher than that made of a single particle size powder [16]. Figure 1 shows the complete preparation of the microwave dielectric ceramic filter.…”