CORROSION BEHAVIOR OF EGYPTIAN COIN ALLOYS IN ARTIFICIAL SWEAT

Abstract

Coins lose their original appearance, color, and clear pits may be formed on the surface. In this work, the corrosion behavior of 25-piaster (25P) and 50-piaster (50P) Egyptian coins were investigated by chemical and electrochemical techniques up to four weeks. The surface morphology of these coins were characterized by optical, scanning electron microscopy and energy dispersive X-ray analysis. The phases identification on the surface coins after four weeks were investigated by X-ray diffraction. The results declared that the rates of corrosion of 50P coins are faster than 25P coins. The investigation of the surface of these coins confirmed the presence of pits and general corrosion. A dezincification process was confirmed by atomic absorption spectroscopy for the 50P Egyptian coins. The specific wear rate of 50P Egyptian coins were more than the 25P Egyptian coins by about 3 folds while immersed in artificial sweat solution showed more increase in the wear.