The Features of Ring-Shaped Deposit Formation upon Evaporation of Magnetic Colloid Droplets in a Magnetic Field

Abstract

The structure of deposits resulting from the evaporation of magnetic colloid droplets has been experimentally studied. It has been shown that the deposit has the largest thickness in the center and at the boundary of a droplet; i.e., a ring-shaped deposit is formed. The width of the ring-shaped (boundary) region of the deposit has been measured and shown to depend on colloid concentration and the action of a nonuniform external magnetic field. In particular, it has been found that, under the action of a magnetic field having a gradient directed to the droplet center, the thickness and width of the ring-shaped region of the deposit decrease.