Particle coating mechanism of fine particles by high-speed gas impact: Wall effects

Recently, there have been various studies on fabrication of composite particles to produce functional materials. Here, high-speed gas impact blending is utilized as a kind of surface-composite method to coat fine particles. The coating mechanism is investigated theoretically and experimentally. It is assumed that small particles move between the surfaces of large particles and the inner wail in collisions. The process is described by the number of small particles coated over the large ones after arbitrary impact times. The experimental results with binary sized particles agreed with simulated ones according to this theory. As a result, it was found that the transfer of small particles between large ones affects the distribution form of the number of small ones over large ones, and that the transfer between large particles and the inner wall governs the average number of small ones in addition. Therefore, it becomes possible to estimate the coating ratio of large particles in a certain processing time by this fabrication method.