Deposition of Colloidal Particles during the Evaporation of Sessile Drops: Dilute Colloidal Dispersions

Abstract EN

The deposition of colloidal silica particles during the evaporation of sessile drops on a smooth substrate has been modeled by the simultaneous solution of the Navier–Stokes equations, the convective-diffusive equation for particles, and the diffusion equation for evaporated vapor in the gas phase.

Isothermal conditions were assumed.

A mapping was created to show the conditions for various deposition patterns for very dilute suspensions.

Based on values of the Peclet (Pe) number and Damkholer numbers (Da and Da−1), the effects of adsorption and desorption were discussed according to the map.

Simulations were also done for suspensions with a high particle concentration to form a solid phase during the evaporation by using a packing criterion.

The simulations predicted the height and width of the ring deposit near the contact line, and the results compared favorably to experimental particle deposition patterns.