Barrier Methods of Rust Prevention
Syllabus 0620 · Topic 9: Metal Extraction & Corrosion
🕵️ The Detective's Brief
You are a corrosion engineer at a materials lab. Your job: find the right armour for every piece of iron. The enemy? Water and oxygen working together. Your weapons? Paint, Oil, and Plastic.
Remember: rust requires BOTH water AND oxygen. Remove either one — and rusting stops.
⚙️ The Core Principle
All barrier methods work by the same single mechanism: they create a physical layer that excludes water and oxygen from contact with the iron surface. No contact → no rusting. Simple, but powerful.
🔧 Choose Your Barrier Method
Click a method to explore how it works and where to use it.
🎯 Match the Method
Select the best barrier method for each object, then check your answers.
⚠️ Examiner Trap
WRONG: "Paint stops rusting because it is waterproof."
RIGHT: "Paint acts as a physical barrier that excludes both water and oxygen from the iron surface."
The examiner wants to see both water AND oxygen mentioned — not just one.
Painting
Permanent, static surfaces
Excludes O₂ + H₂O
Oiling/Greasing
Moving parts, needs reapplying
Excludes O₂ + H₂O
Plastic Coating
Dipped in molten plastic
Excludes O₂ + H₂O
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