Science · 6 pages · 12 min
Why iron rusts only when air and water both arrive
Rust is a small electrochemical cell that needs both oxygen and a water film.
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From the opening
Iron rusts when oxygen and water reach it together, because the damage is a small electrochemical cell spread across the surface. Take away either the air or the water and that cell has no way to keep running. The opening covers a tiny cell on the wet surface, why dry air is not enough, and why salt water speeds the cell.
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Inside
- A tiny cell on the wet surface
- Why dry air is not enough
- Why salt water speeds the cell
- What stainless steel changes
- Where the idea stops applying
- A distinction worth keeping
Sources
- Electrochemical corrosion of iron
- Hydrated iron oxide as the rust product