Types of corrosion protection

Corrosion protection can be carried out in various ways. Some of the measures are already used in material production, others only later. What types of protection exist and what active and passive corrosion protection means can be read here. You will learn how each protection mechanism works.

Active corrosion protection

Active corrosion protection prevents the occurrence of corrosion during chemical-electrical processes. This happens in different ways:

  • By creating a permanently changed electrical potential at the workpiece surface, which prevents the corrosion process from running off (external current application)
  • By "sacrificing" an inferior substance that corrodes instead of the higher quality
  • By combining both ways

In the external current application, the workpiece surface is the negative pole (anode), while another electrode forms the positive pole. If current is applied, no corrosion processes can take place on the negatively charged surface due to electrochemical conditions. But there must be constant flow of electricity. The process is used continuously for example in petroleum pipelines.

In the so-called cathodic corrosion protection system, however, a sacrificial anode is used. These "sacrificed" metal boilers for example a magnesium rod - when oxidized instead of the actual metal. The current released by the reaction creates a potential difference that alters the chemical reaction. As a result, the workpiece is not oxidized, but chemically reduced. Oxidation takes place only at the sacrificial anode.

Passive corrosion protection

In addition to the possibilities of active corrosion protection, metals can also be protected against corrosion by coatings.

coating

The coating can be either metallic (galvanizing, chrome plating), but also made of non-metallic materials (plastics, rubber). It separates the material from the surrounding atmosphere, thus preventing contact with corrosion-inducing compounds. Also paints, oils or powder coatings are possible.

conversion layer

Another possibility is to produce such a protective layer on the material itself by converting the uppermost material layer (anodizing, chromating). In hot dip galvanizing, a sacrificial anode effect is created in addition to the protective oxide layer of the ZInk.

Constructive corrosion protection

When processing components and workpieces made of metal, consideration must also be given to possible corrosion risks.

It is important here to avoid contact corrosion as well as crevice corrosion. This can be done by appropriate design ways as well as by a conscious selection of materials.

Tips & Tricks

Be sure to seal screws in the outside area whenever possible. The gap between the screw and the metal part can also cause corrosion on the metal part surface.

Video Board: Prevention of Corrosion