Effect of Chlorella vulgaris Biofilm Adhesion on Electrochemical Behaviors of Wire Arc-Sprayed Aluminum Coatings

Abstract

Thermal-sprayed aluminum (Al) coatings are widely used for corrosion protection in marine environments. The corrosive nature of seawater and the synergy with marine microbes make for aggressive service environments for Al coatings. In this study, Al coatings were deposited on 316L stainless steel (316L SS) substrates by using wire arc spraying. Chlorella vulgaris, a typical marine fouling algae, was used to investigate the effects of biofilm adhesion on the electrochemical behavior of wire arc-sprayed Al coatings in artificial seawater environment. Electrochemical measurements via dynamic potential polarization curves and electrochemical impedance spectroscopy were used to monitor the corrosion behavior after attachment of microbes on Al coatings and bare, uncoated 316L SS. Analysis of the corrosion products was conducted using scanning electron microscope and energy-dispersive spectrum. The results showed that the Chlorella vulgaris biofilm slowed the corrosion of the Al coatings. This suggested that Chlorella vulgaris biofilm was a critical contributing factor to the corrosion behavior of the Al coatings. Moreover, a mechanism was suggested to illustrate the corrosion behavior of Al coatings in the presence of Chlorella vulgaris.