Definition - What does Sacrificial Coating mean?
A sacrificial coating is a form of corrosion control done through the application of thin metal layers that have lower electrode potential values or those having higher levels in the electrochemical series. It builds a clear barrier or coat throughout the surface being protected.
Corrosionpedia explains Sacrificial Coating
Sacrificial coating is a type of metal coating which will undergo oxidation more than the metal surface that it protects. The best example of this type of coating is zinc-coated steel or galvanized steel. More active sacrificial coating dissolves, depending on the anodic reaction. The electrons released by dissolved zinc or coating atoms will flow to that part of metal that is protected, turning it into a cathode, thus preventing corrosion of the metal.
Furthermore, coatings that are made from more active noble metals, such as steel plated with nickel and tin, can provide protection from corrosion so long as the coating remains intact. All forms of coating defects in the localized area can lead to intensive corrosion, particularly on the part of the steel as it acts similarly to the anode in a galvanic cell. The presence of tin, which is cathodic, hastens steel corrosion.
The substances used to manufacture sacrificial coatings are typically cheap, such as:
- Clear polymers
The polymers account for the weak bonds that facilitate easy removal.
Sacrificial coatings offers benefits including:
- Mostly water based (environment friendly)
- Fast and easy to apply, meaning less disruption
- Invisible, so it does not affect the look of the surface
Essentially, a sacrificial coating works by giving superior surface protection where damage strikes, instead of allowing it to penetrate directly into the substrate.