Drying and Consolidation in Drying Colloidal Dispersions

Abstract

When a thin film of wet paint or coating containing suspended submicron sized colloidal particles is dried on a substrate, evapora- tion of the solvent concentrates the particles. The drying and consolidation process leads to the formation of space filling particle networks and in many cases gives rise to tensile stresses in the network. Drying and consolidation process builds up stresses in the colloidal packing while packing flaws such as voids and dislocations nucleate cracks thereby compromising the mechanical integrity of such materials. An understanding of the fluid-solid phase transition for varying particle size, shape and chemistry (inter-particle interaction), followed by prediction of particle packing as a function of the said parameters in the presence of exter- nal fields is critical to industries as diverse as electronics, paints, coatings, ceramics, and agriculture. The paper presents some of our recent work on the film formation and cracking phenomenon in wet films formed from colloidal dispersions.