Corrosion |
Key Concepts
- Corrosion: the oxidation of metals by certain substances such as water and oxygen in the environment.
- Rusting of iron is a common form of corrosion.
- Noble Metal: a metal resistant to corrosion and found uncombined in nature, eg, gold and silver. These are also known as Cathodic, or Protected, Metals.
- Ignoble Metal: a metal that corrodes. These are also known as Anodic, or Corroding, Metals.
- Passivating metal: a reactive metal that forms an inactive coating as a result of reacting with substances such as oxygen and water, eg, aluminium and chromium.
- In general, corrosion is a spontaneous electrochemical process* which requires:
- an anode where oxidation occurs
- a cathode where reduction occurs
- a metal path to allow for the flow of electrons
- an electrolyte
- Common methods of corrosion prevention are:
- Painting
- Plating with another metal
- Cathodic protection
- Alloying with another metal
*Biological activity can also corrode metals.
Examples: Corrosion (Rusting) of Iron and Preventing Corrosion (Rusting)
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