Agglomeration of suspended nano-particles during coating

The coating process of sub-micron particles was investigated numerically using CFD-DEM simulations. The descending level of the liquid during the drying process is known to dictate the inter-particle capillary interaction and therefore the agglomeration of the particles. The main contribution of this work is the insight of mono-layer structuring of suspended particles during the transient evaporation of the liquid layer. A prior research concerning the modeling of the capillary interaction was applied (Uzi et al., 2014). The incentive forces during nano-suspention coating were modeled and implemented into the computational domain, and constant evaporation rate was assumed during the process. The case of total wetted particles in water at constant temperature was examined, for different particle sizes. It was found that Brownian motion is predominant when the liquid level is relatively high. According to the gradually descending level of the liquid, the capillary interaction overcomes the Brownian random motion, causing the particles to assemble into a stable state long before the substrate is dried. Additionally, the crystallization of the particles establish similarly for different particle sizes in terms of liquid level.