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 the passive alumina layer is strengthened, particularly for long immersion times. The formation of a complex aluminum chelate explains the electrochemical results. Surface analysis indicates that in the presence of 8-HQ, the oxide film is very thin; the adsorption of the organic compound prevents the adsorption of chloride ions and the destruction of the aluminum oxide layer. In acidic solutions, 8-HQ does not modify the corrosion mechanism of aluminum. This result is explained by the solubility of the aluminum chelate in acidic media. This is confirmed by XPS analysis which also reveals a significant adsorption of the organic molecule on the surface.