Corrosion inhibition of AA6060 aluminium alloy by lanthanide salts in chloride solution

The electrochemical behaviour of AA6060 in 3.5% NaCl in the absence and presence of some rare earths has been studied by means of polarisation curves and impedance measurements. We find that the natural protective aluminium oxide layer is damaged after nearly 100 h of immersion time in the aggressive medium. The current–potential curves show that the corrosion resistance of the alloy is greatly enhanced by addition of lanthanide salts especially the cerium ion. This latter forms, on the alloy surface, a passive layer whose protective properties are reinforced by ageing in solution.