Dry particle coating using magnetically assisted impaction coating: Modification of surface properties and optimization of system and operating parameters

The feasibility of using the magnetically assisted impaction coating (MAIC) device to coat fine silica guest particles onto the surface of larger cornstarch and cellulose host particles was examined. This was done to simultaneously improve the flowability of the host particles, as well as reduce their hydrophilicity, making them more suitable for use in foods and pharmaceuticals. The success of coating achieved by MAIC depends on the degree of 'fluidization' of the host/guest particle system caused by the motion of the magnetic particles. To better understand the factors influencing this fluidizing behavior, several critical system and operating parameters were investigated. This was done using a model system consisting of PMMA host particles and alumina guest particles. The system parameters examined were magnetic particle size, mass ratio of magnetic particles to powder (host and guest particles) and guest particle size. The operating parameters were processing time, current (or voltage) and frequency. In addition to varying these parameters, enhanced image processing was used to measure the motion of the magnetic particles in order to study its effect on coating efficiency. The magnetic particles were observed to have both rotational and translational motion. (C) 2000 Elsevier Science S.A.