Corrosion resistance: factors & more

The corrosion resistance of metals is a property that is not easy to answer. It's not just about the metals, but also about the corrosive media to which a metal can be sensitive. You can find out what else you should know about corrosion resistance here.

Corrosion Resistance Factors

On the one hand, there is the type of metal when examining its resistance to corrosion. All non-ferrous metals form a passive layer (oxide layer) that prevents surface corrosion from occurring.

  • Also read - corrosion of aluminum
  • Also read - corrosion of copper
  • Also read - Corrosion protection for the heater

Surface corrosion

Extensive corrosion damage only occurs here if the surface or the oxide layer is damaged. This can be done by a variety of means. Most non-ferrous metals are attacked by strong acids, as these destroy the oxide layer. Mechanical damage can also be the reason for corrosion. In addition, chlorine and other aggressive substances also play a role in the occurrence of corrosion.

Ferrous metals do not form such a protective layer. They rust very quickly as soon as air and moisture act on the surface. Such a protective layer can only be provided to ferrous metals by means of an appropriate alloy, as is the case with stainless steel, for example. The higher the alloyed stainless steel, the more corrosion-resistant it is. However, all other ferrous metals are usually highly prone to corrosion and must be carefully protected.

In contrast, there is copper, and within certain limits also brass. Both metals are highly resistant to corrosion.

Other types of corrosion

However, most metals are equally sensitive to certain types of corrosion. These are above all:

  • Contact corrosion
  • Acid corrosion
  • High temperature corrosion
  • Electro corrosion under suitable conditions

Here, corrosion protection lies primarily in avoiding the triggering conditions or only using materials that can withstand the stresses in the environment.

Especially for high-temperature corrosion, only special alloys that are sufficiently heat-resistant are permitted.

Improvement of the corrosion resistance

This can be done through coatings and coatings (galvanizing, painting, oils) but also through the production of special, more corrosion-resistant alloys. Protecting with sacrificial anodes can also be a way.

Tips & Tricks Pay particular attention to contact corrosion - never use different metals side by side. This also applies to metal plates and screws.