How zinc prevents the iron from rusting?

The zinc coating is in close contact with the iron to be protected, as well as with the moisture that would otherwise rust the iron. This makes it possible for ions and currents to flow through the system. As a result, because the zinc is consumed in preference to the iron as it is a more ready donor or electrons to the system. The zinc is said to act as a 'galvanic anode'.

Eventually the zinc will be consumed, as will the iron.

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