CORROSION

Corrosion is an electrochemical phenomenon that has a very complex nature, which occurs when a metal comes into contact with oxygen that is part of the atmospheric air, as well as humidity (Castaños, 2016).

There are different types of corrosion among them we can mention, the one identifiable by visual inspection, examples of it are the uniform corrosion, pitting, crevice and the galvanic, other type is the one identifiable by inspection by tools, as they are it erosion, cavitation, friction, intergranular, exfoliation and alloy, and the denominated identifiable by microscopic inspection, among them are the cracking, the attack by high temperatures and by microorganisms (Nieto, 2016)

The basic concepts to consider in this phenomenon are: oxidation, reduction, the anode electrodes (element that corrodes) and cathode (element that corrodes).

In the anodic reaction the oxidation of a metal is produced, while the cathode reaction does not necessarily result in reduction, but this will depend on the medium in which it is found; for example, in the acidic medium the following reaction will occur: a hydrogen molecule is produced.

2H+ + 2e- →H2

While in a base medium it refers to the next one: 4 hydroxide ions are produced.

O2 + 2H2O + 4e- → 4OH

Enrique Nieto, president of NACE International in 2016, mentions that there are several factors that intervene either preventing or favoring the corrosive reaction, for example the nature of metals and alloys, the presence of inclusions in the material and on the surface, the homogeneity of the metallic structure; I also had these factors have to do with the nature of the corrosive medium and with the agents that are found in the environment as the presence of oxygen, temperature, fluid movement of the metal and the presence of external electrical currents (here it involves the intensity of current (I), the duration (t), the molecular mass of the target (M), valence of the metal ion (n), and Faraday's constant (f) ), since these accelerate the process of corrosion.

Is a phenomenon that can occur naturally or human-induced, this involves the destruction of materials usually metal when they come into contact with oxygen. The oxide formed by corrosion is usually orange-brown in color, whose formula is Fe2O3. This phenomenon affects automobiles, boats, bridges and constructions that are exposed to atmospheric agents, and causes a decrease in efficiency and safety, therefore, it could cause human, environmental and economic losses.