Wetting of graphite by molten magnesium

Abstract

The contact angle between molten magnesium and graphite was measured at 973K in order to obtain basic data for magnesium-base composite manufacturing. Two kinds of sessile drop methods were used for the purpose: the conventional method in which solid magnesium was put on graphite prior to heating and another method in which molten magnesium was dropped on graphite by a metal dropping device. In the conventional sessile drop method, though it was difficult to melt magnesium due to the surface oxidation, pure magnesium droplet could be finally gotten after trial and error. It was possible to easily get pure magnesium droplet in the sessile drop method using a dropping device, and magnesium evaporated rapidly. The contact angle between molten magnesium and graphite was estimated to be about 125 deg from the results obtained by the two methods. It was guessed that molten magnesium and graphite were bonded at the interface by the weak intermolecular force, because the work of adhesion was calculated to be 7 kJ/mol.