Effects of vibration frequency and time on packed density of powder

A uniform mixture of silicon powder (granularity ≤ 0.044 mm) and polyvinyl alcohol solution (PVA, 5 wt%) in response to a certain proportion was prepared. After sieving, prilling and vibration, the mixture was packed. Effects of the vibration frequency (14-50 Hz) and time (10-230 s) on packed density of powder were studied. It is shown that the packed density of powder is influenced by vibration frequency significantly. While the vibration frequency is equal to or less than 29 Hz, there is no boiling or size segregation. The packed density of the powder will approach constant after vibration sometime. As the frequency increases, the velocity of densification accelerates. While the vibration frequency is 29-50 Hz, the powder presents boiling and size segregation, which makes the powder inhomogeneous. Moreover, boiling and size segregation become more and more severe with the increasing frequency.