Effect of Alloy Elements on the Performance of Al Sacrificial Anode

Abstract

Al-Bi-Ga alloy is a good sacrificial anode material, but research on its electrochemical performance in seawater, freshwater, and soil is limited. This article focuses on Al-Bi-Ga-Pb-In and Al-Bi-Ga-Sn-In alloys. The working potential, current efficiency, and corrosion morphology of aluminum alloys under constant current conditions were studied through electrochemical performance testing, microstructure observation, and composition detection. The influence of alloy elements (Bi, Ga, Pb) on the electrochemical performance of aluminum alloys was analyzed. The results indicate that the dissolution morphology of Al-Bi-Ga-Sn-In is better than that of Al-Bi-Ga-Pb-In, and the distribution of Bi element in Al-Bi-Ga-Sn-In is more extensive. The destruction of the oxide film on the surface of aluminum alloy is more uniform, exhibiting better dissolution morphology; As the Bi content increases, the corrosion rate shows a trend of first increasing, then decreasing, and then increasing. The current efficiency first decreases and then increases, usually stopping and rebounding around 4.5%; Ga can increase the corrosion rate and reduce the surface impedance value; When the Ga content is greater than 0.10%, the corrosion rate significantly increases; As the Ga content increases, the current efficiency first decreases and then increases, then stops decreasing and rebounds around 0.2%.