Inhibitors for the protection of aerospace aluminium alloy

Chromate pigmented paints are commonly used in painting the aluminium parts of the aircrafts. This study is directed to find an alternative inhibitor in place of chromate the most widely used inhibitor in aircraft paints. In that effect sodium benzoate, polyacrylic acid (PAA), strontium chloride, cerium chloride, malic acid, glycin, cobalt sulphate, pyrrol, and quartamin T (alkyl three methyl ammonium chloride) were tried in place of Na₂CrO₄. The anodic and cathodic polarisation curves were recorded and weight loss measurements were carried out in 0.1 M NaCl solutions with and without inhibitor. Quartamin T, pyrrol and PAA which were observed to provide satisfactory inhibition effect were added to the polyurethane based paints used in the aircraft industry and the Al (2024) alloy painted with this paint was subjected to electrochemical corrosion tests in 0.1 M NaCl. Pyrrol and quartamin T containing paints were observed to give results as good as those obtained with chromate containing paints.