Preliminary study of the anti-corrosion performance of different protection systems applied to two World War II aluminium alloy archaeological objects with different surface finishes

Abstract

This article looks at the conservation of historic aircraft from the Second World War, testing different coatings to protect their aluminium alloy structures from corrosion. Five different protective protection systems, including Paraloid™ B72, wax, Dinitrol™, Multi Matt Clear Lesonal™ and carboxylates, were evaluated by being applied to artefacts from WWII aircraft wrecks, in particular a wing fragment from a Supermarine Spitfire and a propeller blade from a P38 Lightning, which presented different surface conditions. The protected objects were exposed to real-life conditions (uncontrolled indoor environment). Advanced analytical techniques such as electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), optical coherence tomography (OCT) and scanning electron microscopy (SEM) were used to characterize the evolution and effectiveness of the protection systems. The results showed different degrees of effectiveness for different coatings. Dinitrol™ and Lesonal™ demonstrated the best protective properties, forming thin but effective layers that enhance corrosion resistance. Carboxylates, on the other hand, proved ineffective, while Paraloid™ B72 and wax were not very effective and unsuitable for objects with original paint residues.