Metal products gradually become rusty over time. Structures are destroyed, practically turn into dust. To avoid such sad results, you need to know what metal corrosion is and how to protect against it. The metal undergoes destruction due to the influence of the external environment on it, which can be electrochemical or chemical. Chemical corrosion appears in environments that are not capable of conducting electric current (petroleum products, gases, alcohols). All metals are subject to it. Electrochemical corrosion occurs due to the appearance of an electrolytic film on the metal due to the influence of the environment. In particular, industrial and domestic s alts used on roads in winter and stray currents have an effect. There are many ways and methods by which corrosion protection is carried out.
The most popular and widespread is the use of paintwork. They are metallic and inorganic non-metallic. Coatings based on synthetic polymers provide greater efficiency. Inorganic non-metallic coatings are very diverse. These include paints (oil, alkyd and enamels), as well as varnishes (tar, synthetic, bituminous). When applied, such corrosion protection creates a thin film that protects the metal from moisture and environmental influences. Varnishes and paints are very easy to apply, affordable. At the beginning of work, it is necessary to strictly follow the technology of their application. It is necessary to cover the metal surface with them in several layers in order to better protect the structures from atmospheric influence.
Metal coating-inhibitors are of two types. The first includes protective coatings with cadmium, zinc, and aluminum. To the second - corrosion-resistant coatings with copper, silver, lead, nickel and chromium.
Depending on the mechanism of action of corrosion protection, it is called cathodic or anodic. There are metallic inhibitor coatings that are more electronegative and coatings that are more electropositive. Anode coatings belong to the first type, cathodic - to the second. Aluminum and zinc are used as anode coatings, nickel, copper, and tin are used as cathodic coatings.
Different methods of protecting metals from corrosion also involve several options for applying coatings. For example, to apply inhibitors, a chemical method is used to coat metal structures with other metals: aluminum, zinc.
If the metal structure is already corroded, then additives in the form ofpassivators and inhibitors. Contribute to the inhibition of corrosion processes in alkaline and neutral environments such strong oxidizing agents as s alts of alkaline earth and alkali metals. To protect reinforcement in reinforced concrete, calcium nitrite-nitrate is used.
When it is necessary to protect against corrosion caused by the external environment and precipitation, volatile inhibitors are used, which are substances that adsorb on the metal surface from the air or condense on it, forming a thin layer.
