行星式球磨颗粒流场分布与形貌变化规律

The flow field distribution of particles in the planetary ball milling is explored based on the discrete element simulation. The relative velocity distribution of ball-particle group collision during the ball milling is calculated. Then the collision scene of a single ball is extracted, and the impact field of multi-layer particles is simulated to study the interlaminar compressive stress distribution. The planetary ball milling experiments of Al/PTFE mixed particles and Al particles were carried out, and the average diameter of particles at different time is recorded to characterize the change of particles morphology. The theory of the average diameter change of particles based on the broken probability and the fractal number of particle group is proposed.The results of discrete element simulation show that the low velocity collision is the main part of the ball-particle group collision. Only 1% of collision is the relative high velocity collision with normalized velocity ξ>0.33, and the Weibull distribution can well characterize the distribution of relative collision velocity. As for the impact field of multi-layer particles, the distribution of the multi-layer particles' interlayer compressive stress tends to be dumbbell-shaped or gourd-shaped with the increase in ball collision velocity. The experimental results show that the average diameter of particles shows the exponential decaywith the increase in milling time.