Mechanical-dry coating of wax onto copper powder by ball milling

Mechanical dry coating process has been applied to formation of the oxidation protecting film of polymer wax onto spherical copper particles (median diameter of 69.1 mum) using a conventional ball milling. The wax used here showed poor adhesiveness to the metal surface and low plasticity at room temperature due to relatively hard and high melting point (446 K). In order to determine the necessary mechanical force for adhering between the metal and the wax without any deformation of metal particles, the coating experiments were carried out with process variables as processing time, wax content and combination of different kinds of wax. The degree of surface coverage of wax film related to the operating conditions was evaluated by means of the dissolution experiment with acid solution in the optical cell. It has been shown that the addition of the soft wax as a sealant material for filling the cavity of the hard wax was effective to stabilize the coating state and to enhance the degree of coverage. (C) 2002 Published by Elsevier Science B.V.