Long term corrosion of aluminium materials of heritage: analysis and diagnosis of aeronautic collection

Abstract

The large use of aluminium alloys for the twentieth century induces that numerous components and objects in aluminium are registered in many collections in museums or are classified as historic buildings. In collaboration with the Air and Space Museum at Le Bourget (France), the objective of the authors' work was to identify and study the different processes of corrosion of Al alloys occurring in the aircrafts collection from 1930 to now. Chemical and metallographic analyses allowed the identification of various alloys used in different aircrafts. The long-term corrosion products are mainly constituted by amorphous Al(OH)3. The corrosion behaviour of the complex systems 'alloys/corrosion layer' was evaluated by electrochemical measurements. The results show that thick corrosion layers have a poor influence on the corrosion rate of the metallic substrate. On the other hand, the presence of painting residues with corrosion products is beneficial for the conservation because of the presence of mineral inhibiting compounds.