SIMULATION OF BALL MOTION FOR ANALYSIS OF COATING PHENOMENA DURING TUMBLER-BALL MILLING OF CU POWDER

A copper powder was milled in argon by a tumbler-ball mill to investigate the formation of copper coatings on ball surfaces and mill pot walls, which must be a significant process in mechanical alloying. Weight ratio of the coatings to an initial powder-filling was measured after milling at various ball- and powder-filling ratios. Experimental results on the coating weight ratio were analyzed by a two-dimensional computer simulation of ball motion. It was found that the coating weight ratio increases with an increase in the ball-filling ratio in a range of the ratios from 10 to 40% and it decreases rapidly between 50 and 60%. It was also found that the coating mass ratio decreases with increase in the powder-filling ratio. The computer simulation revealed that the coating behavior is in a close relation to the ball motion which was simulated by taking into account the consumption of kinetic energy of milling balls. It was found that the coating mass ratio depends on the frequency of impacts per ball.