Influence of silicon on the corrosion behavior of Al–Zn–In sacrificial anode

Abstract

Abstract Steel structures used in offshore sectors are often exposed to adverse weather conditions, and thus, require the application of efficient and safe corrosion protection techniques. The application of sacrificial anodes with aluminum alloys for cathodic protection is a viable anticorrosive protection alternative for long-term wet conditions owing to its low density, galvanic economy, better performance, availability, and recyclability. This study aims to evaluate the effect of different percentages of silicon in commercial Al-Zn-In alloys, used in aluminum sacrificial anodes, on the electrochemical properties of the alloys. The DNV-RP-B401 standard was used to analyze the electrochemical performance and manufacturing of commercial matrix alloys according to the prescribed chemical composition. They were characterized by optical emission spectrometry, electrochemical performance, electrochemical polarization assay, macrography, and scanning electron microscopy. The results revealed greater work efficiency and corrosion uniformity for aluminum cathodic protection anodes with the addition of 0.10% by weight of silicon, which resulted in disk shape precipitation and reduced grain size and smaller spacing between dendritic arms. Therefore, with this percentage of silicon, the anodes exhibit less automatic corrosion of the anode mass, that is, greater anticorrosive protection, smaller amounts of corrosion residues in the medium, less anode disposal with exhausted life, and greater application sustainability for the aluminum anode.