Estimation of coating time in the magnetically assisted impaction coating process

A model is developed for estimating the coating time in a magnetically assisted impaction coating (MAIC) device. The mixture of the host, guest and magnetic particles is assumed to be in a fluidized state where the distribution of velocities is a Maxwell–Boltzman type. It is assumed that the collisions among the particles are important for impinging the guest particles onto the surface of host particles, and thus forming a semi-permanent coating on the surface of host particles. The coating time is shown to depend on several parameters, including the number density of host particles, the diameter ratio of the host and guest particles, the height of the fluidized particle bed and the material properties of the host and guest particles. Our model shows that there is an optimal value of the bed height for which the coating time is a minimum. The coating time increases sharply when the bed height is smaller or larger than the optimal value, and also when the diameter of host particles is increased. A comparison of the model results with experimental data shows surprisingly good agreement for the coating time as a function of host particle surface covered considering the many assumptions that were made in deriving the model.