Abstract
Auto-granulation is the growth of particle clusters within a dry, fine powder bed due to the bulk powder cohesion. This clustering occurs without the addition of any binder to the system due to simple agitation of a powder, such as during storage or handling. For this reason, it is important in powder processing to be able to characterize this behavior. In this study, a sub-micron titania powder is mechanically vibrated under controlled conditions to induce clustering and promote auto-granulation. The amplitude and frequency of the vibration is varied to view the effect on the equilibrium granule size. A statistical model of the effect is also developed to determine that the granule size increases linearly with vibrational energy. Furthermore, imaging of cross-sections of the granules is conducted to provide insight into to the internal microstructure and measure the packing fraction of the constituent particles. It is found that under all vibrational conditions investigated the particles exhibit a core-rim microstructure.