Enhancing corrosion resistance of anodized AA7075 alloys by electrodeposition of superhydrophobic coatings

Abstract

Electrodeposition of superhydrophobic coatings was carried out on anodized AA7075 alloy to further enhance its corrosion resistance. Several compositions of electrodeposition bath were studied to find the most suitable one to obtain superhydrophobic coating. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy proved the deposition of coatings with different characteristics depending on electrodeposition bath composition. Highest contact angle value (∼ 160°) and highest corrosion resistance were obtained for the Mn-containing coating, proving also high stability after 21 days of immersion in an aqueous solution mimicking seawater. Experiments on flat pellet samples were carried out to split the effect due to the material composition with respect to that due to the coating morphological features, estimating the vacuum fraction of the superhydrophobic coatings according to the Cassie Baxter model.