Active corrosion protection describes all protective treatments of metallic surfaces that have an active corrosion-inhibiting effect.
A distinction is made between two types of active corrosion protection. The first possibility is the use of so-called corrosion inhibitors. These neutralise the harmful effect of corrosion-promoting media by chemical bonding. For example, hydrochloric acid and hydrogen sulphide corrosion can be prevented by the targeted addition of these "destimulants". Iron dissolution and hydrogen embrittlement during de-rusting and descaling of structural steels with diluted acids can also be prevented.
DThe second approach is known as cathodic corrosion protection (CCP) and is mainly used where metals come into contact with corrosive media such as water. Active corrosion protection is produced by zinc-containing coatings and zinc alloys (aluminium, nickel, magnesium). The principle: In the event of a corrosion attack, the zinc is oxidised while the underlying iron component is protected. The zinc sacrifices itself, which is why we speak of a "sacrificial anode". Due to its electrical conductivity, zinc plating also has a certain "remote effect" and can also protect distant areas of the component. Oxidation produces white rust until the zinc is used up. The zinc flake coating picks up this mechanism and transfers the principle to a paintable system.