Corrosion

Formation of Oxides

Corrosion:

The chemical reaction which occurs between a metal and oxygen which results in the formation of a new substance called an oxide.

It’s important to know too that there are both positive and negative forms of corrosion.

Negative Corrosion

Commonly known as RUSTING Iron and steel react with oxygen and forms

rust (forms an oxide). Rust eats away at the metal and then

reacts like a sponge, sucking up water and other pollutants until a hole is formed in the metal.

Positive Corrosion

Aluminum undergoes positive corrosion such as when your baking pans at home develop the gray coating on the metal.The gray coating is actually aluminum oxide,

or corrosion, which protects the metal.

Preventing Corrosion

To prevent corrosion you need to coat the metal with something else, such as paint, oil or undercoating.

By covering the metal with another material you are preventing the oxygen from getting at the metal and starting the corrosion process.

Continued…

Using alloys can also prevent corrosion as some metals are more prone to corrosion than others. What are alloys?

We now use alternate materials for some things metals used to be used for. For example bumpers on cars are now made of molded plastics.

Questions

Do questions 5 and 6 on page 35.