In this protection method, the metallic structure to be protected is connected by a wire to a
more anodic metal, so that all the corrosion is concentrated at this more active metal.
The more active metal itself gets corroded slowly, while the parent structure is protected.
Since the more active metal sacrifices itself, by undergoing corrosion and saving the base
metal, the method is named as Sacrificial anode method or auxillary anode method.
When the piece of more active metal gets corroded completely, it is simply replaced by new
piece.
Most of the common sacrificial anodes are based on the alloys of magnesium, zinc and
aluminium which are placed above iron in electrochemical or galvanic series.
Applications of this method are seen to protect cables or iron pipelines, by connecting them
to Mg- block and in case of marine structures ships are protected by using Zn-plates as
sacrificial anode. Even water tanks, boilers are protected by using Zn metal.
