Galvanisation protects iron from rusting by coating it with a thin layer of:

Galvanisation protects iron from rusting by coating it with a thin layer of Zinc metal only. Galvanisation is the process of applying a protective zinc coating to iron or steel to prevent rusting. The zinc layer creates a physical barrier that prevents moisture and oxygen from reaching the underlying iron. Zinc is more reactive than iron. If the coating is scratched, the zinc acts as a sacrificial anode, meaning it corrodes in place of the iron to protect the exposed metal. While galvanisation is a common and effective method for protecting iron, several other techniques are used such as alloying and electroplating.