AN INVESTIGATION OF THE CORROSION INHIBITION OF PURE ALUMINUM IN NEUTRAL AND ACIDIC CHLORIDE SOLUTIONS

This work is devoted to the corrosion inhibition of pure aluminum by 8 -hydroxy-quinoline (8-HQ). In neutral solutions, steady-state current- voltage curves and electrochemical impedance measurements show that th e passive alumina layer is strengthened, particularly for long immersi on times. The formation of a complex aluminum chelate explains the ele ctrochemical results. Surface analysis indicates that in the presence of 8-HQ, the oxide film is very thin; the adsorption of the organic co mpound prevents the adsorption of chloride ions and the destruction of the aluminum oxide layer. In acidic solutions, 8-HQ does not modify t he corrosion mechanism of aluminum. This result is explained by the so lubility of the aluminum chelate in acidic media. This is confirmed by XPS analysis which also reveals a significant adsorption of the organ ic molecule on the surface.