AN INVESTIGATION OF THE EFFECT OF POWDER ON THE IMPACT CHARACTERISTICS BETWEEN A BALL AND A PLATE USING FREE FALLING EXPERIMENTS

The study of the mechanisms of mechanical alloying requires knowledge of the impact characteristics between the ball and vial in the presenc e of milling powders. In this paper, foe falling experiments have br c n used to investigate the characteristics of impact events involved in mechanical milling. The effects of milling conditions, including impa ct velocity, ball size and powder thickness. on the coefficient of res titution and impact force are studied. It is found that the powder has a significant influence on the impact process due to its porous struc ture. This effect can be demonstrated using a modified Kelvin model. T his study also confirms that the impact force is a relevant parameter for characterising the impact event due to its sensitivity to the mill ing conditions. (C) 1998 Elsevier Science S.A.