The main application of these anodes is for cathodic protection of steel structures in sea water. Although these anodes can be used in fresh water or soil in rare cases. In order to prevent the formation of a passive layer of aluminum oxide on the surface of the anode, which causes a sharp decrease in the efficiency of the anode, an activating element such as mercury or indium is usually used in the chemical composition of aluminum anodes. In the past, more mercury was used in the chemical composition of aluminum anodes. Although the amount of mercury in the alloy was low, but with the consumption of the main body of the anode, this amount of mercury remained in the material and its concentration increased, which caused many environmental problems. Today, the use of mercury in aluminum anode is almost obsolete and indium element is used as an activator.
Common standards for aluminum anodes include BS 7361, DNV-RP-B401, IPS-M-TP-750, NACE-RP0387, NORSOK M-503 and MIL-DTL-24779B.