New EoL routes of Al Li aircraft integral LBW and FSW welded panels including new Cr free coatings

EoL of new aircraft integral welded panels of 3rd generation of Al-Li alloys welded between them by Laser Beam Welding (LBW) and Friction Stir Welded (FSW), including new Cr-free coatings to protect them was investigated. The best EoL route including dismantling and recycling procedures was defined for 10 different combinations of FSW/LBW Al-Li alloys and two coatings.

Different cutting strategies, ranging from cutting only for size reduction to full separation of all materials, including the separation of the welded seam were defined with the objective to recycle the maximum amount of material to manufacture high quality aircraft Al-Li alloys. Furthermore, the need to eliminate primer and topcoats and different decoating methods were investigated for TFSAA (Thin film Sulphuric Anodizing) and Sol Gel coatings. The separated metallic fractions of the different EoL routes were recycled and the produced metallic alloys characterised in order to establish a ranking in terms of costs, environmental impact and effectivity, that allowed to select the best option for recycling for each LBW and FSW panels.

Fading/enrichment of the different elements were researched, and the recycled alloys were compared with commercial primary Al-Li alloys to determine the compatibility with each of them. Materials and energy flows, emissions and waste generation were inventoried during the new End of Live process tested and provided to ecoTech project for the Life Cycle Assessment (LCA). The best EoL route was defined to valorize as much as possible of the valuable alloying elements and minimize the environmental impact: cutting only for size reduction (6 FSW and 3 LBW configurations) and full separation of all materials (1 LBW configuration).