What happens during metal corrosion?


Metals can corrode. However, such corrosion in metals can take place in different ways and according to different conditions. Also, not all metals tend to certain types of corrosion. Read more about the corrosion of metals in this article.

Electrochemical and chemical corrosion

Electrochemical corrosion

As a rule, metals undergo electrochemical corrosion in the everyday temperature range. For this you need:

  • an anode
  • a cathode
  • a potential difference between anode and cathodes
  • an electrolyte

The anode and cathode may also be present on the metal itself (surface corrosion), or the surrounding soil or other nearby metal may be anode or cathode. The electrolyte is sufficient for any type of aqueous solution containing ions. But the humidity of the environment is sufficient in many cases as a conductive medium.

The reverse of this process is used for rust removal or for active corrosion protection.

Chemical corrosion

In the high temperature range, the corrosion is no longer caused by electrochemical means, but by the direct action of individual substances. Chemical corrosion is also referred to as high temperature corrosion.

corrosion tendency

The tendency to corrosion of the individual metals and alloys varies. The most common and fastest way to corrode unalloyed or low-alloyed ferrous metals. Copper and its alloys, on the other hand, are highly resistant to corrosion. Although steels are ferrous metals, they are usually alloyed with corrosion-inhibiting substances and are therefore often highly corrosion-resistant.

corrosion protection

Metals can be protected in different ways against corrosion. The individual types of corrosion protection depend on the weaknesses of the respective metal.

These can be coatings with zinc (galvanizing), but also the alloying of metals with corrosion-inhibiting alloy components. Painting is also a means of corrosion protection.

Tips & Tricks

Especially in the car corrosion protection is particularly important. Although the sheets are galvanized and painted, the tendency to corrosion is still very high because of the environmental influences and the construction method.


Video Board: Rust: Prevention and treatment | Chemistry for All | The Fuse School