Characterizing the effect of surface morphology on particle-wall interaction by the airflow method

Particle-wall interaction has been studied by the airflow method. The particles used were micrometer-size polymethyl methacrylate (PMMA) spheres treated with an additive, i.e. nanometer-size TiO2, Al2O3 or SiO2 particles. The method for the treatment was dry particle coating based on mechanofusion or simple mixing through shaking manually. The surface morphology of the PMMA particles was modified by changing the species of additives, its concentration and the treatment method. The particles after treatment were dispersed on the surface of a flat metal piece and an experiment on particle entrainment was carried out in an airflow channel to evaluate particle-wall interaction. Relationships between particle entrainment efficiency and air velocity, which corresponds to the distribution of the particle-wall interaction force, were obtained under various conditions, showing that the particle-wall interaction force tends to decrease with the increase in the concentration of added nanoparticles. Furthermore, analysis of the experimental results showed that the main factor affecting the particle-wall interaction force was the actual surface morphology of the particles after treatment.