Standard hull-mounting zinc anodes of various chemical compositions were immersed in water at the Norfolk Reserve Fleet site and supplied current continuously to a large steel sea wall for 36 weeks. The current was monitored daily during the initial week and 3-4 times weekly thereafter. At the conclusion of the test, the anodes were cleaned, weighed, and analyzed chemically. Electrochemical efficiencies and current outputs were determined.
Data are presented showing the performance of all anodes with graphical representation of typical specimens. Zinc anodes containing iron up to 0.006 percent and small additions of aluminum (to 0.5 percent) and cadmium (to 0.10 percent) outperformed the high-purity zinc anodes (0.0014 percent iron). There was some evidence that the addition of 0.1 percent aluminum without cadmium improves the performance of high-purity zinc. All anodes containing iron up to a maximum of 0.006 percent and aluminum and cadmium in any proportion within the limits of composition tested performed equally well. Minimum contents of 0.025 percent cadmium and 0.1 percent aluminum were indicated. 5.2.2
