Inhibiting the corrosion of aluminum alloy 6063 with inorganic compounds in a 3-percent sodium solution

Some inorganic compounds have been tested as corrosion inhibitors for 6063 aluminium alloy in 3% NaCl by electrochemical and metalographic methods. The compounds were MoO42-, CrO42-, NO2- oxo-anions and Li+ and Mg2+ metallic cations. Results obtained show that these compounds inhibited corrosion of 6063 aluminium alloy, and that the Li+ cations were the best inhibitors. The difference between pitting potential and corrosion potential increase by increasing the concentration of Li+. The maximum inhibition efficiency (E% = 85%) was attained at 5 x 10(-3) M. Increasing temperature from 25 to 55degreesC improve corrosion resistance of 6063 aluminium alloy in the absence of Li+. However, in the presence of these cations, E% decreased at elevated temperature.