Colloidal Interactions and Particle Clustering in Consolidating Pigment Coating Layers

The structure formation during consolidation of pigment coating layers was simulated using a three-dimensional particle dynamics model. In addition to hydrodynamic interactions, the model included colloidal interactions as well as the Brownian motion. The influence of colloidal model parameters on the z-direction structure formation and coating layer shrinkage was studied. Simulations were carried out using realistic process parameters and coating system properties. The colloidal interaction parameters were found to have an influence on the internal microstructure of the coating layer and on the overall thickness of the coating. Lower particle surface potential generated particle clusters, which resulted in reduced shrinking. The electrostatic double layer thickness was shown to primarily affect the internal structure of the coating. The work contributes to the understanding of the effects the colloidal properties of the pigment coating slurry have on the structure formation of the coating layer. The results may also aid in the dosing of chemical additives to obtain a coating layer of desirable porosity and structural properties.