A Stability Diagram for Dense Suspensions of Model Colloidal Al2O3-Particles in Shear Flow

TL;DR

This paper investigates the microstructure and stability of dense Al2O3 colloidal suspensions under shear flow using simulations, revealing cluster formation and layering phenomena, summarized in a comprehensive stability diagram.

Contribution

It introduces a stability diagram for dense Al2O3 suspensions, linking microstructure formation to shear conditions and inter-particle interactions, based on simulation results.

Findings

Cluster formation occurs on two length scales, independent of observation scale.

Non-attractive interactions lead to layered structures in shear flow.

Microstructure stability depends on shear conditions and particle interactions.

Abstract

In Al2O3 suspensions, depending on the experimental conditions very different microstructures can be found, comprising fluid like suspensions, a repulsive structure, and a clustered microstructure. For technical processing in ceramics, the knowledge of the microstructure is of importance, since it essentially determines the stability of a workpiece to be produced. To enlighten this topic, we investigate these suspensions under shear by means of simulations. We observe cluster formation on two different length scales: the distance of nearest neighbors and on the length scale of the system size. We find that the clustering behavior does not depend on the length scale of observation. If inter-particle interactions are not attractive the particles form layers in the shear flow. The results are summarized in a stability diagram.