Corrosion resistance of aluminium alloys for civil and industrial applications

Considering the long service life which is normally expected for buildings, the maintenance cost, the quality and durability of construction materials are strongly affected by triggering of spontaneous degradation processes. As regards specifically metallic materials, awareness of their corrosion behaviour in service condition, in every environment they can get in contact during life, is essential, for maintenance and cleaning operations as well. Corrosion rate measurements can be obtained from electrochemical tests. Corrosion mechanism of metallic alloy is a spontaneous phenomenon, but some factors, as alloying elements, microstructure, surface treatments and environments, may enhance this degradation process. This thesis focuses on understanding corrosion behaviour of three aluminium alloys, Al5083, Al6082 and Al7075, with different surface treatments, tested in two aqueous solutions at different pH conditions (one environment simulating a cleaning detergent and the second environment simulating a strong alkaline solution). The corrosion rate was obtained from corrosion current densities, measured by electrochemical laboratory tests. Results, in terms of Open-Circuit Potential (OCP) and potentiodynamic measurements are reported and discussed. Lastly, SEM and EDX analysis have been used as characterization techniques for microstructure analysis.