Effect of Zinc Addition on the Performance of Aluminum as a Sacrificial Anode for Mild Steel Protection in Seawater.

Corrosion is a major challenge affecting the durability of mild steel structures in marine environments. This study investigates the effect of zinc addition on the performance of aluminum as a sacrificial anode for the protection of mild steel in seawater. Aluminum is widely used in cathodic protection systems due to its high electrochemical efficiency; however, its tendency to form a passive oxide layer limits its effectiveness. The incorporation of zinc as an alloying element was explored to enhance the anodic performance of aluminum.
Aluminum-zinc alloys with varying zinc compositions (0wt%, 2wt%, 4wt%, and 6wt%) were prepared and tested. The experimental analysis included weight loss measurements, determination of polarized potential, current carrying capacity, and anode efficiency. The results showed that the addition of zinc significantly improved the sacrificial properties of aluminum, with the 2wt% Zn alloy demonstrating the highest anode efficiency and corrosion protection. Excess zinc beyond this level (4wt% and 6wt%) led to decreased efficiency due to overactivation and increased dissolution rates.
The study concludes that 2wt% Zn is the optimal composition for enhancing aluminum’s performance as a sacrificial anode, providing superior protection for mild steel in seawater. These findings contribute to the development of more efficient and cost-effective cathodic protection systems for marine infrastructure.