Corrosion of metals - the process of their destruction

Corrosion is translated from Latin as "corrosive". This is the name of the process of destruction of any material (wood, ceramics, polymer, metal) as a result of the impact of the environment on it, be it ground, air, water (sea, river, marsh, lake, underground) or any other medium. With respect to metals, the term corrosion of metals is replaced by the generalized word "rust". For example, in the oxygen corrosion of iron in water, iron hydroxide is hydrated - ordinary rust.

Corrosion of metals leads to large losses -for Russia is the annual loss of millions of tons of valuable metals. More than 10% of the annual production of metal pipes become unsuitable due to corrosion. For the same reason, metal constructions of various structures buried in the ground, storage tanks for oil and other minerals become unsuitable for 3-4 years if they are not protected from the destructive effect of soil and ground corrosion. Corrosion of electrical cables and communication cables, bottoms of swimming equipment, hulls of cars and other vehicles.

Soil-ground corrosion of metals -electrochemical process, depending on such factors as the chemical composition of soils, their humidity and air permeability, the type of metal, its homogeneity, the nature of the surface of metallic objects.

In order to protect metal in the ground (water,air, other environments), you need to know the reasons that corrosion of metals can be caused. To obtain data on the degree of corrosion activity of soils necessary for developing measures to protect metal structures from corrosion, complex field and laboratory studies of soils are carried out.

Protection of metals against corrosion is based on such methods:

1. Increasing the chemical resistance for structural materials (introduction of corrosion-resistant elements into alloys or, conversely, removal of impurities from the alloy that accelerate corrosion);

2. Isolation of the metal surface from the influence of an aggressive environment (application of lacquers on metal, insulating films, electroplating coatings);

3. electrochemical protection - under the influence of superimposed external current on the metal structure;

4. Reduction of the aggressiveness of the medium by introducing corrosion inhibitors (arsenates, chromates, nitrites), deoxygenation or neutralization of the medium.

These methods are divided into 2 groups. The first two methods are performed before the operation of the metal product at the design or manufacturing stage, and it will be impossible to change anything during the operation. Two other methods are implemented only when the metalware is used and the protection mode can be changed depending on the changed actual environmental conditions.

Such a question as the protection of metal from corrosion,remains and is now topical, requiring an integrated approach to the search for modern design solutions, the improvement of old proven protective methods and means.