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GCSE Design and Technology · key term
A surface layer that separates a material from substances that would cause corrosion, such as water and oxygen.
Used by Edexcel
Specification 3a · Paper 1
Revise: Corrosion and OxidationA barrier coating keeps the metal separate from the substances that attack it. For iron and steel, the aim is to prevent water and oxygen reaching the surface. A coating must remain continuous: a scratch or an uncoated area exposes the metal again.
Explain the difference between a scratched barrier coating and scratched galvanising: zinc can still protect exposed iron by corroding instead.
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