What Does Noble Coating Mean?
A noble coating is a protective coating in the form of a thin metallic layer that is applied to a metal substrate to prevent corrosion. The thin coating layer is more noble (less reactive) than the metal onto which it is being applied. The noble coating protects the metal that is being coated from harsh environments where corrosion is possible.
Corrosionpedia Explains Noble Coating
A noble coating is only effective if it is undamaged. If the noble coating layer becomes damaged, the metal being coated will undergo more rapid localized corrosion due to galvanic reactions.
Common noble coatings include nickel, tin and chromium, although these coatings are only considered noble coatings if they are applied to a metal substrate that is less noble than they are.
The opposite of a noble coating is a sacrificial coating. This is a coating in which a less noble material is applied to a more noble metal substrate. The sacrificial coating will corrode before the material being coated. One of the benefits of a sacrificial coating over a noble coating is that localized damage will not necessarily cause an intense increase in localized corrosion.