why will an iron object that is plated with zinc NOT rust if the layer of zinc gets scratched?

Question

anonymous · Answer

I had to educate myself on this but this is based on the assumption that iron is exposed by the scratch: http://en.wikipedia.org/wiki/Plating#Zinc_plating http://www.waterheaterrescue.com/pages/WHRpages/English/Longevity/water-heater-anodes.html It would appear that if the scratch penetrates to the iron that the zinc is more electrolytically reactive and will "sacrifice" itself to protect the iron.

anonymous · Answer

so that means that the zinc would react first and form a layer of the zinc compound ti shield the iron?

anonymous · Answer

From reading the sites in question it would be appear that the water around the scratch would be more likely to interact with the zinc and create a power than interact with the iron and rust.

anonymous · Answer

Since zinc is a reducing agent when compared to iron, as long as it maintains contact with the iron it will react first. The iron will be reduced by the zinc until all the zinc layer has reacted.