The inhibition effect of inorganic compounds on the corrosion of 3003 aluminium alloy in chloride medium

This study concerns the inhibition of the corrosion of the aluminium alloy 3003 in a solution of 3 % NaCl by Li+, Mg2+, MoO42-, NO2- and CrO42- ions. The methods used are the determination of the polarization curves and the metallographic examination of the surface condition. The results obtained show that the tested ions inhibit the corrosion process. The comparative study of the effect of these ions shows that the Mg2+ ions are the most efficient ones in the temperature range from 25 to 65degreesC. The inhibition efficiency increases with the concentration of these ions and reaches a maximum value of 86 % for 5 x 10(-2) alloy. As a consequence, the gap between pitting and corrosion potentials becomes larger. At 75degreesC, Mg2+ ions tend to stimulate corrosion of alloy 3003 in the chloride solution considered.