Environmentally Friendly Composites and Surface Treatments for Metal-to-Composite Hybrid Joints for Marine Application

In this study, the use of natural fibres (flax and basalt) in combination with a recyclable epoxy matrix based on cleavable amines is suggested for improving the sustainability of marine industry. In addition, a new and eco-friendly anodizing process based on tartaric sulfuric acid solution (TSA) and a pore widening step in a NaOH aqueous solution was carried out on aluminium alloy (AA5083) to evaluate its effect on the adhesion strength and damage tolerance after low velocity impact of co-cured adhesive joints with a basalt fibre reinforced and recyclable laminate. The durability in marine environment was simulated by exposing samples to salt-fog spray conditions over a period of 90 days. Results highlighted the potential of the proposed natural fibre composites, even though the interfacial adhesion with the recyclable matrix needs to be improved, while the anodizing treatment significantly increased the damage tolerance of the joints irrespective of ageing, impact energy and temperature compared to the reference joints.