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Question

Why don't other metals have the ability to form a protective layer on them after corrosion,like aluminium and copper?

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Solution

Aluminum and copper have self-protecting corrosion mechanism, but other metals (Fe, Ni etc.) do not have this.

When iron corrodes, it forms a layer of rust (oxides and hydrous oxides). Rust does not adhere to the iron very well, and atmosphere can penetrate underneth the layer of rust and attack fresh iron metal layers beneath. This is why a piece of iron left out in the open will rust through and through. Painting or putting on a protective coat of silcone can slow down the corrosive degradation of iron. Stainless steel is an alloy of iron that contains other materials (carbon, nickel) that essentially disrupts the corrosion reaction and stops it.

Aluminum and Copper form oxide layers that adhere to the metal, and prevents the atmospheric corrosion from penetrating below the oxide layer. This protects the metal beneath the outer corroded layer.

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