The corrosion protection is primarily due to the anodic potential dissolution of zinc versus iron. Zinc acts as a sacrificial anode for protecting iron (steel). While steel is close to -400 mV, depending on alloy composition, electroplated zinc is much more anodic with -980 mV. Steel is preserved from corrosion by cathodic protection. Alloying zinc with cobalt or nickel at levels less than 1% has minimal effect on the potential; but both alloys improve the capacity of the zinc layer to develop a chromate film by conversion coating. This further enhances corrosion protection.