Analysis of Chromate-based Primers for Protection of Aluminium Alloys on Historical Aircraft

Immediately following the use of aluminium alloys, particularly Duralumin, in construction aircraft, protective coatings with anti-corrosion properties were developed. Among numerous solutions to prevent corrosion, most widely employed materials organic primers containing chromates. This paper reports study corrosion inhibitive compounds (chromates) used by aircraft manufacturers during World War II. More specifically, we have identified nature and assessed their current efficiency. Our analyses on samples collected from three different wrecks (French German) excavated terrestrial sites reveal that primer contained either zinc tetroxychromate or lead chromate. Using XANES chromium oxidation states elucidated phenomena taking place aging paint primer. We found reduction Cr(VI) Cr(III) species occurred within at interface Al alloy. is believed be due alteration layer its long exposure natural environment. However, even after 80 years, still present these archaeological parts. Although a little altered, chromate compound can provide source inhibitor, thus maintaining protection alloys.