Electrospun polymeric coatings on aluminum alloy as a straightforward approach for corrosion protection

Several metals and alloys are susceptible to corrosion attack and this usually implies the accurate selection of a specific material depending on the working conditions and the characteristics of the environment to which it will be exposed to. However, it could represent a restriction at the same time because a limited range of materials can be practically considered. In addition, they could be also characterized by unsuitable properties for the intended application and high costs. To address this issue, polymeric coatings exhibit high potentiality to be a valid alternative to toxic chromates, allowing to deal with the most appropriate metallic materials and affordable deposition procedures. In this work, polyvinyl alcohol (PVA) fibrous coating was successfully collected onto aluminum alloy-6082 by means of electrospinning technique. The anticorrosion performance of the final system has been evaluated in 3 wt % NaCl solution by means of electrochemical impedance spectroscopy (EIS). To avoid PVA disintegration in aqueous environment, several crosslinking procedures were assessed using glyoxal. The two most promising ones (120°C for 60 min and 150°C for 15 min) were then considered for a further investigation. Crosslinked PVA mats showed improved properties as compared to the as-spun case, as demonstrated by mechanical and thermal analyses. Electrochemical tests revealed that crosslinked coatings can protect aluminum substrates against corrosion, especially for the electrospun PVA coating treated at 120°C. In this case, after 270 h, a significant corrosion resistance of about 26 kΩ was recorded with respect to the blank alloy (about 3.8 kΩ).